BBC "Space" Progamme on Black Holes
Martin Brown
stereotypical Hollywood mad dog black hole "the size of a
pea" invade the solar system and lay waste Jupiter and the
Sun. I quote:
> Black Holes are the Universe's ultimate monsters, sucking everything
> into their super-dense centres. There are an estimated ten million of
>
> these cosmic killers in our galaxy and once created they never die.
>
> What are the chances of Earth having a fatal encounter?
>
The latter question was never answered in the programme, but
a lot of time was spent looking at expensive computer
generated special effects animations of the sun going down
the plughole.
> from
>
> http://www.bbc.co.uk/science/space/spaceguide/space_prog/index.shtml
>
So I though I might have a shot at estimating how
devastating a black hole the size of a pea entering our
solar system might really be, and what observable effects it
might have.
Ignoring for the moment the probability of this actually
happening, and the bounds that are already present on the
number density of low mass primordial black holes. Here are
my attempts at predicting what would happen. Please feel
free to correct any obvious blunders!
For comparison I'll also try a micro black hole mass 10^21
kg (big asteroid mass), make it a big pea and use Earth's
mass for the middle case, and finally a 3 solar mass BH for
the big bad wolf. Since there are intentional gross
approximations everywhere and unintentional ones quite
likely to creep in uninvited I am content to get numbers to
the nearest order of magnitude or so.
To keep the sums easy I have assumed that the object is
inbound at around the rough speed of nearby stars v ~10^5
m/s, and that the solar wind near the Earth is outbound at u
~10^7 m/s with an ion density of j ~10^7 per m^3. Round
numbers are preferred.
Accretion power based on the mass in the space swept clear
by the BH each second and scales with Rs^2. It will
obviously increase gradually as the object gets closer to
the sun.
Type Mass Rs KE=1/2mv^2
Accretion Power Output at 1AU
Micro 10^21 kg 2 um 10^31 J 0.04uW
(Ceres)
Mini 10^24 kg 1 cm 10^34 J 1W
(Earth)
Midi 10^31 kg 10 km 10^41 J 1000GW
(3Msun)
My tentative conclusion is that apart from annoying
astrometric observers by transient gravitational lensing
effects and introducing unexpected perturbations into
planetary positions the Micro and the Mini BH would seem to
be observationally very difficult to detect as long as they
don't actually hit any material denser than the solar wind
or get too close to a planet. A sun grazer could be pretty
exciting though, but even then would it suffer enough
braking to hang around or would it always have enough speed
to escape again?
It can't pick up enough mass to make any appreciable
difference so if there is a braking effect it must come from
the radiation pressure of the shockwave ahead of it.
I think that they would pretty much drop in on a parabolic
orbit swing round the sun and then leave again having
violently swept up a clear path through the solar wind.
Pretty much like any other visiting comet. But if they
should hit something chunky then they do real damage !
Once a BH hits solid material my quick and dirty
calculations are much less reliable. But I reckon it can
punch through anything as a pure KE round without losing
very much of its initial momentum. Indestructible and at a
speed of 10^5 m/s it cuts through an Earth diameter in about
a minute. And even the smallest one considered here has a
burn rate through rock that equates to roughly a 100MT of
TNT explosions per second. (1MT TNT taken as 5x10^12 J,
rock density 5000kg/m^3)
Such a collision it would become very obvious from the waste
heat and other side effects. But has anyone done the
calculations properly for the case of a BH hits a fair sized
planet ?
I reckon there could be even more fun and games if the
inbound black hole was maximally spinning parallel to it's
direction of motion so that when it hits dense material it
will be preceded by a relativistic jet that should cut like
a knife through butter.
The big black heavy hole would mess things up mightily, but
then so would any close approach by an ordinary common or
garden star of a similar mass.
What is a black hole's Roche limit for ripping material off
the surface of the sun ?
I expect the classical solutions are well out line for this
but lets give it a try anyway.
I get an expression which roughly simplifies to:
r = 0.0025 M^(1/3)
This gives Roche limits of 25km, 250km and 50000km
respectively. (Could be wildly wrong!)
Would the solar system really be laid waste by a visiting
black hole the size of a pea?
I am not convinced. What do others think ?
It is fairly obvious from Gauss's theorem that being 6400km
from a quiescent black hole with the same mass as the Earth
you will feel 1g acceleration towards it and could
comfortably travel around it in a circular 90 minute low
Earth orbit equivalent for a very long period of time.
There are bound to be typos and mistakes in this so I'd be
grateful for any corrections or suggested improvements. My
astrophysics is pretty rusty these days...
Regards,
Martin Brown
Tom Roberts
> Would the solar system really be laid waste by a visiting
> black hole the size of a pea?
I think it depends A LOT on the conditions with which the black hole
enters the solar system. A one-time fly-through would be INCREDIBLY
unlikely to be noticed; a collision with the earth would be devastating
(but (INCREDIBLY UNLIKELY)^2 (:-)).
But I think that our observations of millions of stars and solar systems
similar to our own indicate that such devastation does not happen very
often. By pea-sized black holes or any other mechanism (but there are
those terrestrial mass extinctions, and their hint of a periodicity...).
I wouldn't waste sleepless nights worrying about this....
Tom Roberts tjro...@lucent.com
Oriel36
> I wouldn't waste sleepless nights worrying about this....
>
>
> Tom Roberts tjro...@lucent.com
Tom,
I think you are missing the point insofar as when the interior
structure of a BH is left at a loose end,it becomes a conceptual loose
cannon and you are beginning to see the effects of this as Martin
points out.This is what happens when an abstract concept and reality
blur (multiple Universe,wormholes,ect) and the inability to
distinquish or set boundaries can lead to to a dismal situation.The
only analogy I can think of is the inability to distinquish between a
dream and normal reasoning and I would rather a sleepless night than
mixing dreams and normal reasoning.
Gerald
Martin Brown
Tom Roberts wrote:
> Martin Brown wrote:
> > Would the solar system really be laid waste by a visiting
> > black hole the size of a pea?
>
> I think it depends A LOT on the conditions with which the black hole
> enters the solar system. A one-time fly-through would be INCREDIBLY
> unlikely to be noticed; a collision with the earth would be devastating
> (but (INCREDIBLY UNLIKELY)^2 (:-)).
Indeed, but in the extremely unlikely event should occur I would quite like
to have someone else check my assumptions and numbers before I beat the BBC
over the head with them.
I object to the Disneyfiction of science, and this programme really was
special effects first, international actor with gravitas and VR acting
experience from Jurrasic park second with the science taking a dismal third
place. I think the few bits of science in it were repeats of shots from a
previous Horizon programme (also not a particularly good one).
> But I think that our observations of millions of stars and solar systems
> similar to our own indicate that such devastation does not happen very
> often. By pea-sized black holes or any other mechanism (but there are
> those terrestrial mass extinctions, and their hint of a periodicity...).
Probably it is reckonned whenever we go through the galactic plane.
> I wouldn't waste sleepless nights worrying about this....
My worry is that the BBC has lost it's way as a public service broadcaster.
But I'd be really glad if someone would check over my numbers.
Regards,
Martin Brown
Jim Jastrzebski
> > > Would the solar system really be laid waste by a visiting
> > > black hole the size of a pea?
It's a wrong question unless you consider "size" an indication
of the "mass" of the black hole.
You can consider any electron to be a black hole and yet
none of them does any harm. If one of them had mass e.g.
1000 kg it might. So the harm your pea would do to the solar
system depends rather on its mass not to mention its path
through the solar system. But then it is the same problem
with any other object, not necessarily with BH (which is
a hypothetical creature anyway).
-- Jim
Michael Varney
"Jim Jastrzebski" <Jim...@aol.com> wrote in message
news:3B743B65...@aol.com...
> Martin Brown wrote:
>
> > > > Would the solar system really be laid waste by a visiting
> > > > black hole the size of a pea?
>
> It's a wrong question unless you consider "size" an indication
> of the "mass" of the black hole.
True.
> You can consider any electron to be a black hole and yet
Umm, electrons do not have many properties of a black hole.
Try again.
> none of them does any harm.
Electrons hurt like hell if you have enough of them.
> If one of them had mass
Electrons do have mass.
> e.g.
> 1000 kg it might. So the harm your pea would do to the solar
> system depends rather on its mass not to mention its path
> through the solar system.
True, to a certain extent.
> But then it is the same problem
> with any other object, not necessarily with BH (which is
> a hypothetical creature anyway).
Black holes are much more than hypothetical as we have empirical evidence of
their existence.
Oriel36
> I object to the Disneyfiction of science, and this programme really was
> special effects first, international actor with gravitas and VR acting
> experience from Jurrasic park second with the science taking a dismal third
> place. I think the few bits of science in it were repeats of shots from a
> previous Horizon programme (also not a particularly good one).
Martin,
Only a few postings ago you remarked that anything goes with a BH so
why are you complaining that the BBC is taking liberties with the
material?.If you were allowed to explain a black hole for the viewing
public,how would you do it without relying on it's effects?.As far as
it goes,the documentary makers are just acting on the idea that the
structure, is in your words 'a private matter' so what choice did they
have ?,could you do any better and again, how would you accomplish it
?.This is a straightforward honest question and the challenge is to
recover commonsense to this material without being mundane or
launching into gibberish.
Gerald
Martin Brown
Jim Jastrzebski wrote:
> Martin Brown wrote:
>
> > > > Would the solar system really be laid waste by a visiting
> > > > black hole the size of a pea?
>
> It's a wrong question unless you consider "size" an indication
> of the "mass" of the black hole.
They are intimately related - Schwarzchild radius is from Rs =
2GM/c^2
A naive classical derivation by the Rev Michell predates GR by more
than a century.
Things are more complex if it is a spinning BH, using the Kerr
metric but it only changes the size at the equator by a factor of
two or so.
I was being generous and interpretted "size of a pea" to mean its
radius and generously rounded it up so that if anything the version
in the programme would have been weaker.
Still it would be fun to see how well a BH with the mass of a pea
might do instead.
Mpea ~ 0.1g = 10^-4 kg
So Rs(pea) = 10^-34 m
Methinks it won't be hanging around for long enough even to measure
it's speed.
Hawking radiation which varies as 1/M^2 will kill it stone dead in
the blink of an eye.
tevap ~ 10^-47 s
by my approximate reckoning. So it goes pop immediately after
formation with an instantaneous yield of 10^13 J or about 2 MT TNT
equivalent. Noticable. Especially at ground zero, but not very
likely to devour the Earth. It doesn't last long enough to consume
anything at all.
Regards,
Martin Brown
Aladar Stolmar
The flaw in your calculation is the assumed independence of volume and
mass. The nuclear material shows a constant density, which you have
to accept as governing principle for any massive dense body! Forget the
stupidities about the 'degeneration pressures'!
This understanding limits the mass density therefore there is no possibility of
a black hole.
m = 4/3*Pi*r^3*1536^2*3/32* rho_0/(1-7.4234e-28*m/r)^2
Defines the free standing nuclei type bodies' mass and radius relation,
with the added constrain that (1-7.4234e-28*m/r) > 0. I got for this
critical radius (when it would turn 0) the half of Schwarzchild's radius.
The meaning of Schwarzchild's radius in my representation is only that
the local light speed at that distance is the half of what is it in the vacuum.
z = 7.4234e-28*m/r - gravitational red-shift.
The equation has a maximum at M = 5.819 solar masses and R=14,276 m.
At that point the gravitational red-shift (effecting the gravitational pull
force) z = 0.6.
It is unlikely that the larger mass nuclei type - neutron star type - objects
could form, only the same radius smaller mass objects seem plausible.
See lower curve on the graph. It is extremely interesting that the known
neutron stars are around 1.4 solar masses - horizontal red line - and it
falls under the maximum in the masses, indicated by the vertical red line.
The possible process from this graph is the temporary formation of higher
mass and an explosive - gamma ray burst - reduction of mass from
maximum mass and corresponding radius state (5.82 solar masses and
about 28.5 km diameter) to about the same radius but around 1.4 solar
mass more stabile state on the lower curve.
http://www2.3dresearch.com/~alistolmar/Stars%20and%20supernova.htm
It also limits the force on the massive bodies in this region:
F12(m1/r) = G*(1-z)^2 * m1 * m20 / sq-rt(1-v2^2/c^2/(1-z)^ 2) / r^2
Which means that in the event the massive body would get down
to this size, the gravitational force from the first massive body would
decrease close to 0, so anything outside of this radius will pull away the
masses from the center. No "gravitational collapse" alleged process
would occur. Sounds like a supernova event to me. The central region is
transforming into a neutron star - and the size is limited by the decrease
of inward force below the outward directed force from the gravity of the
bodies not yet approaching the region. No black holes, no event horizons.
--
Aladar
http://www2.3dresearch.com/~alistolmar/nature.htm
Charles Francis
<Jim...@aol.com> writes
>Martin Brown wrote:
>
>> > > Would the solar system really be laid waste by a visiting
>> > > black hole the size of a pea?
>
>It's a wrong question unless you consider "size" an indication
>of the "mass" of the black hole.
Since black holes are measured in terms of the Scharzschild radius
R = 2GM/c^2
size is a measure of the mass of the black hole.
>. So the harm your pea would do to the solar
>system depends rather on its mass not to mention its path
>through the solar system.
A black hole the size of a pea will have a mass of more than 1/10th the
earth. If it doesn't hit anything but comes close may cause a certain
deviation in the orbits of planets, which could have a knock on effect
of even more disturbed whether patterns. If it hits then it will do
about the same amount of damage as a comet of the same mass. I suspect
not a lot of life would survive a direct hit to the earth.
>But then it is the same problem
>with any other object,
yes.
>not necessarily with BH (which is
>a hypothetical creature anyway).
It is not reasonable to call black holes hypothetical without throwing
out pretty well our whole understanding of modern science. Certainly a
theory of quantum space time may altogether alter the way in which we
think the inner structure of black holes works, but the external
structure, i.e. what an observer could see of them, is unlikely to be
altered.
Regards
--
Charles Francis
Gerry Quinn
>A black hole the size of a pea will have a mass of more than 1/10th the
>earth. If it doesn't hit anything but comes close may cause a certain
>deviation in the orbits of planets, which could have a knock on effect
>of even more disturbed whether patterns. If it hits then it will do
>about the same amount of damage as a comet of the same mass. I suspect
>not a lot of life would survive a direct hit to the earth.
>
Comets couple electromagnetically to the earth - black holes only
gravitationally.
A comet of 1/10 the earth's mass would utterly destroy the planet,
releasing enough energy to raise the average temperature by several
thousand degrees. Survival would be zero. Future beings, if any, might
bask in the light of extra moons.
A black hole of that mass, assuming it passed through, would cause
tremendous tidal disruptions along its path, intense planetwide seismic
disruption, and two zones of volcanic explosion equivalent to major
impacts (the exit wound probably being the nastier...). It's hard to
tell what life might survive, but the odds are definitely better than
for the comet.
- Gerry Quinn
Aladar Stolmar
news:OjYwM5AZ...@clef.demon.co.uk...
> In article <3B743B65...@aol.com>, Jim Jastrzebski
> <Jim...@aol.com> writes
> >Martin Brown wrote:
> >
> >> > > Would the solar system really be laid waste by a visiting
> >> > > black hole the size of a pea?
> >
> >It's a wrong question unless you consider "size" an indication
> >of the "mass" of the black hole.
>
> Since black holes are measured in terms of the Scharzschild radius
>
> R = 2GM/c^2
>
> size is a measure of the mass of the black hole.
Since this measure is by itself a circular argument, based on the
assumption that the speed of light can be reached, and since there is
an observed limit on the density of nuclear matter - which has to
be considered equally for the neutron stars.
This limits the mass density therefore there is no possibility of
a black hole. The correct neutron star mass and radius relation is:
m = 4/3*Pi*r^3*1536^2*3/32* rho_0/(1-7.4234e-28*m/r)^2
> >. So the harm your pea would do to the solar
> >system depends rather on its mass not to mention its path
> >through the solar system.
>
> A black hole the size of a pea will have a mass of more than 1/10th the
> earth. If it doesn't hit anything but comes close may cause a certain
> deviation in the orbits of planets, which could have a knock on effect
> of even more disturbed whether patterns. If it hits then it will do
> about the same amount of damage as a comet of the same mass. I suspect
> not a lot of life would survive a direct hit to the earth.
>
>
> >But then it is the same problem
> >with any other object,
>
> yes.
>
> >not necessarily with BH (which is
> >a hypothetical creature anyway).
>
> It is not reasonable to call black holes hypothetical without throwing
> out pretty well our whole understanding of modern science.
But this is about seventy years overdue now... And yes, I'm throwing
out the good portion of hoaxes called "modern science"...
> Certainly a
> theory of quantum space time may altogether alter the way in which we
> think the inner structure of black holes works, but the external
> structure, i.e. what an observer could see of them, is unlikely to be
> altered.
Since it is a hoax, it just discarded...
>
>
>
> Regards
>
> --
> Charles Francis
I...@te.spam
wrote:
>Comets couple electromagnetically to the earth - black holes only
>gravitationally.
Say what? since when are comets anything more than electrically
neutral in the most part?
>
>A comet of 1/10 the earth's mass would utterly destroy the planet,
>releasing enough energy to raise the average temperature by several
>thousand degrees. Survival would be zero. Future beings, if any, might
>bask in the light of extra moons.
anything with 1/10 the earth's mass would destroy the planet.
>
>A black hole of that mass, assuming it passed through, would cause
>tremendous tidal disruptions along its path, intense planetwide seismic
>disruption, and two zones of volcanic explosion equivalent to major
>impacts (the exit wound probably being the nastier...). It's hard to
>tell what life might survive, but the odds are definitely better than
>for the comet.
Well this is interesting, as the blackhole got close to earth you'll
soon get to the point where the blackhole's gravity is stronger than
the earth's as cows and people fly into it (remember more of a
blackhole's mass is near it's "surface"). Granted this 1/10th mass
blackhole is ummm.. about 1 mm in diameter or so. The first floating
people may think they invented antigravity *grin*. But as it hits
the atmosphere it'd literally become a vacuum cleaner sucking up the
atmosphere as it creates a lower pressure forcing all the air to rush
into it. Now depending upon the speed with dictate damage, unlike
physical impacts the slower blackhole would do more damage. As it
sucks air it gets bigger.. it'll rip though the earth like it doesn't
exist gaining mass as it flies though (and radius).. Of course the
over all radius will never be bigger than about 1cm (and that's the
case of sucking the whole planet up). Just pray that it has escape
velocity and doesn't start oscillating back and forth. Of course
dunno how blackhole "burp" so who knows what might happen else. THose
are just a set of minimum problems.
>
>- Gerry Quinn
Gerry Quinn
>On Sun, 12 Aug 2001 09:14:02 GMT, ger...@indigo.ie (Gerry Quinn)
>wrote:
>
>
>>Comets couple electromagnetically to the earth - black holes only
>>gravitationally.
>Say what? since when are comets anything more than electrically
>neutral in the most part?
You're right, I guess, it's the size and the propensity for breaking up
that really count.
Assuming both travel at 10-20 km/s relative to the earth, the
weightlessness you suggest will happen for up to about 30 seconds -
anything not tied down will tend to fly towards the black hole once it
gets within a few thousand km.
I'm assuming that the bulk of the earth stays stuck in place, though, so
as the black hole passes through there will be a wave of
enormous compression towards the axis of travel, followed by a
springback which will release devastating amounts of energy. Just a bit
less devastating than the comet, though...
- Gerry Quinn
Michael Varney
<I...@te.spam> wrote in message
news:8r9dnt85mt7sh0l2v...@4ax.com...
> On Sun, 12 Aug 2001 09:14:02 GMT, ger...@indigo.ie (Gerry Quinn)
> wrote:
>
>
> >Comets couple electromagnetically to the earth - black holes only
> >gravitationally.
> Say what? since when are comets anything more than electrically
> neutral in the most part?
> >
> >A comet of 1/10 the earth's mass would utterly destroy the planet,
> >releasing enough energy to raise the average temperature by several
> >thousand degrees. Survival would be zero. Future beings, if any, might
> >bask in the light of extra moons.
> anything with 1/10 the earth's mass would destroy the planet.
> >
> >A black hole of that mass, assuming it passed through, would cause
> >tremendous tidal disruptions along its path, intense planetwide seismic
> >disruption, and two zones of volcanic explosion equivalent to major
> >impacts (the exit wound probably being the nastier...). It's hard to
> >tell what life might survive, but the odds are definitely better than
> >for the comet.
> Well this is interesting, as the blackhole got close to earth you'll
> soon get to the point where the blackhole's gravity is stronger than
> the earth's as cows and people fly into it (remember more of a
> blackhole's mass is near it's "surface").
*sigh*
I...@te.spam
wrote:
>
>I'm assuming that the bulk of the earth stays stuck in place, though, so
>as the black hole passes through there will be a wave of
>enormous compression towards the axis of travel, followed by a
>springback which will release devastating amounts of energy. Just a bit
>less devastating than the comet, though...
Now, I was going to type that same thing, then I realized, wait that
wont happen. the earth will be pulled towards the blackhole, but as
it flies through the Earth and continues on it's merry way the Earth
wont jerk back into place. This gravitational attraction isn't
instant, and it doesn't end instantly either.
>
>- Gerry Quinn
Charles Francis
were talking about and would not waste your time writing large amounts
of gobbledigook.
In article <O1vd7.95325$EP6.23...@news1.rdc2.pa.home.com>, Aladar
Stolmar <alist...@3dresearch.com> writes
Regards
--
Charles Francis
Martin Brown
Gerry Quinn wrote:
> In article <OjYwM5AZ...@clef.demon.co.uk>, Charles Francis <cha...@clef.demon.co.uk> wrote:
>
> >about the same amount of damage as a comet of the same mass. I suspect
> >not a lot of life would survive a direct hit to the earth.
>
> Comets couple electromagnetically to the earth - black holes only
> gravitationally.
I don't think that is quite true.
A black hole that size will have enough field gradient to overcome the instrinsic tensile strength of
rock out to around 30m or so, and the acceleration and collisional friction of material close to the
event horizon will be more than enough to ionise it completely. The forward shockwave around the
object will do a nice job of coupling energy transfer to the unfortunate Earth.
Chances are at 10^5 m/s it is travelling faster than the speed of sound, even in the iron core.
However, the black hole by being so small and indestructible meets less resistance to progress and
dumps considerably less energy on the Earth as a consequence.
By my reckonning a comet of mass 10^23 stopped by the Earth (@ 10^5 m/s) ~ 10^33 J
Whereas the mass of material a similar mass BH will sweep out on passing through an Earth diameter
will be ~ 10^10kg which on it's entering the event horizon yields at most 10^27 J
(about 1 million times less energy delivered than by the comet as classical kinetic energy)
The question I haven't been able to solve is how effective would the BH's leading shockwave be at
converting the kinetic energy of the object into heat by decelerating it. I think it is a second
order effect, but I am not entirely sure.
> A comet of 1/10 the earth's mass would utterly destroy the planet,
> releasing enough energy to raise the average temperature by several
> thousand degrees. Survival would be zero. Future beings, if any, might
> bask in the light of extra moons.
>
> A black hole of that mass, assuming it passed through, would cause
> tremendous tidal disruptions along its path, intense planetwide seismic
> disruption, and two zones of volcanic explosion equivalent to major
> impacts (the exit wound probably being the nastier...). It's hard to
> tell what life might survive, but the odds are definitely better than
> for the comet.
Both are probably more than enough to annihilate the planet. I think it would be similar, except
perhaps that the BH would probably do less damage on it's way in through the atmosphere than the
physically much larger comet. Although interesting effects would be observed in the region where the
vertical component of it's gravity exceeds 1g (the last 20s for an observer at ground zero when it is
closer than ~ 2000km). Buildings are not likely to stand up well to large sideways accelerations
either.
The ensuing bipolar vulcanism would probably see off any survivors.
What is an interesting observation is that for some mass ranges of impactor the black hole would
appear to do less overall damage than it's classical counterpart with equal mass.
Regards,
Martin Brown
Martin Brown
Aladar Stolmar wrote:
> "Martin Brown" <martin...@pandora.be> wrote in message
> news:3B74F64E...@pandora.be...
> >
> > Jim Jastrzebski wrote:
> >
> > > Martin Brown wrote:
> > >
> > > > > > Would the solar system really be laid waste by a visiting
> > > > > > black hole the size of a pea?
> > >
> > > It's a wrong question unless you consider "size" an indication
> > > of the "mass" of the black hole.
> >
> > They are intimately related - Schwarzchild radius is from Rs = 2GM/c^2
[snip]
> The flaw in your calculation is the assumed independence of volume and
> mass. The nuclear material shows a constant density, which you have
> to accept as governing principle for any massive dense body! Forget the
> stupidities about the 'degeneration pressures'!
>
> This understanding limits the mass density therefore there is no possibility of
> a black hole.
>
> m = 4/3*Pi*r^3*1536^2*3/32* rho_0/(1-7.4234e-28*m/r)^2
>
> Defines the free standing nuclei type bodies' mass and radius relation,
> with the added constrain that (1-7.4234e-28*m/r) > 0. I got for this
> critical radius (when it would turn 0) the half of Schwarzchild's radius.
> The meaning of Schwarzchild's radius in my representation is only that
> the local light speed at that distance is the half of what is it in the vacuum.
I refer you to Uncle Al's calculation of the odds of a crank coming up with a
useful statement that actually describes how our universe behaves by stringing
together words at random.
Message-ID: <3B6DBF4E...@hate.spam.net>
I fear he may have been overly optimistic.
Regards,
Martin Brown
Gerry Quinn
You misunderstand me. Imagine that a black hole a tenth the mass of the
Earth is moving through the Earth at 20 km/s. Close to the black hole
will be an accretion zone releasing huge amounts of energy. This energy,
converted into heat, will create a pressure which opposes the immense
pressure of magma gravitationally attracted to the black hole. As the
black hole progresses, regions of magma close to its axis will become
tremendously compressed as it passes. After it passes, they will spring
back. In fact, the earth will vibrate like a water droplet - I estimate
that the surface will oscillate by several kilometres, hurling people
into the air and causing volcanic outbursts everywhere.
Hmm, it's beginning to look almost as bad as the comet, except on a
purely geological level...
- Gerry Quinn
Gerry Quinn
>> Well this is interesting, as the blackhole got close to earth you'll
>> soon get to the point where the blackhole's gravity is stronger than
>> the earth's as cows and people fly into it (remember more of a
>> blackhole's mass is near it's "surface").
>
>*sigh*
>
At 20 km/s, the black hole's gravity will indeed exceed the Earth's
locally for 30 seconds or so.
Perhaps you should devote some of the time you spend making moronic
one-line insults to learning some rudiments of physics.
- Gerry Quinn
Aladar Stolmar
radius estimates, nuclear radius and mass - you would see that the
equation deduced from my theory describes the reality, when the
black holes remain pure speculation.
m = 4/3*Pi*r^3*rho_nu/(1-G/c^2*m/r)^2
Try rho_nu = 1.5146667e17 kg/m^3 and see that the neutronstars
lay on the graph drawn by this equation. Which has a Daisy-petal
shape and the position under the peak on the lower portion is the
place where the suggested by the same curve supernovae event
drops the neutron stars...
--
Aladar
http://www2.3dresearch.com/~alistolmar/CMBR.htm
"Charles Francis" <cha...@clef.demon.co.uk> wrote in message
news:PXCwhXAz...@clef.demon.co.uk...
Aladar Stolmar
>
> I fear he may have been overly optimistic.
>
> Regards,
> Martin Brown
>
Which is also could mean that you are unable to understand the
meaning of my equation. Let's try it with words: The nuclear density
is constant. Observed fact. Assume that the constant density
is caused by the exact ratio between the nuclear density and the
background substance density. But the background substance density
changes as a function of governing mass and distance from its center
as rho_nu / (1-G/c^2 * M/R)^2. It is also an observed fact: gravitational
redshift, light bending, Shapiro effect or light speed decrease.
Now use for the calculation of the nuclear mass enclosed by the radius
the density at the boundary layer. Bingo!
M = 4/3 *Pi* R^3 * rho_nu / (1-G/c^2 * M/R)^2 - and this equation really
results the observed neutron star radius and mass! On the only logical
place on the Daisy-petal shape graph, right from the peak on the
lower part of the curve!
[I just noticed that for the nuclear density the exact radius is fund only
if the shape (Cat's Eye Nebula's shape(!)) is considered, which
requires a modification as:
M = 3.65625/3*Pi*R^3*rho_nu/(1-G/c^2*M/R)^2
rho_nu=1.5146667e17 kg/m^3 for G/c^2*M/R ---> 0 results the observed
radius of nuclei and for the solar mass range the observed neutron
star masses and radii!]
--
Aladar
http://www2.3dresearch.com/~alistolmar/CMBR.htm
I...@te.spam
wrote:
>In article <sBBd7.326$Z81.3...@news.uswest.net>, "Michael Varney" <mva...@muswest.net> wrote:
Oooh was that "*sigh*" a moronic insult towards me? Maybe next time
inside of copying the whole statement and typing one word he'll learn
that if he TRUELY thought what I had to say was "moronic" he'd do a
snip job instead of further perpetuating my comments.
Well I guess it's better than what ol' Ali babbles on constantly
about. Atleast a killfile can take care of that.
Michael Varney
"Gerry Quinn" <ger...@indigo.ie> wrote in message
news:AGNd7.1162$s5.2...@news.indigo.ie...
*sigh*
"more of a black hole's mass is near its surface"?
*smirk*
Ok. What surface?
How do you know?
What percentage? Prove this with numbers?
"At 20 km/s, the black hole's gravity will indeed exceed the Earth's
locally for 30 seconds or so."
At what distance? Define "locally". What about gradients? Tidal? Twit.
You pontificate with absolute conviction yet do not support with math. You
fuck up nomenclature and you state properties that you make up.
I put it to you to devote the time you spend making moronic multi-paragraph
statements on learning some basic physics.
Michael Varney
<I...@te.spam> wrote in message
news:2tufntk7ikucoq3bp...@4ax.com...
Then do it, turd. As if I care that you read me or not. Your loss, not
mine.
Gerry Quinn
>
>"Gerry Quinn" <ger...@indigo.ie> wrote in message
>news:AGNd7.1162$s5.2...@news.indigo.ie...
>> In article <sBBd7.326$Z81.3...@news.uswest.net>, "Michael Varney"
><mva...@muswest.net> wrote:
>> >> Well this is interesting, as the blackhole got close to earth you'll
>> >> soon get to the point where the blackhole's gravity is stronger than
>> >> the earth's as cows and people fly into it (remember more of a
>> >> blackhole's mass is near it's "surface").
>> >
>> >*sigh*
>> >
>>
>> At 20 km/s, the black hole's gravity will indeed exceed the Earth's
>> locally for 30 seconds or so.
>>
>> Perhaps you should devote some of the time you spend making moronic
>> one-line insults to learning some rudiments of physics.
>
>*sigh*
>"more of a black hole's mass is near its surface"?
>
>*smirk*
>
>Ok. What surface?
>How do you know?
>What percentage? Prove this with numbers?
A Newtonian approximation is the most suitable way to analyse the static
gravitational effects being discussed, and in terms of this
approximation the statement is entirely valid. Of course, one might
require a more sophisticated metric for certain purposes, but none of
them are relevant here. We could model frame-dragging as a
perturbation of the Newtonian approximation, but at 20km/s, any
gravitomagnetic effects will be insignificant in any case. He is quite
correct that cows and people will fly towards it, though they will
probably reach only the accretion zone rather than the black hole
proper.
In the metric appropriate to the Newtonian approximation, the black hole
will have a Schwarzschild radius of less than a millimetre. The
appropriate 'surface' will be at the radius where the pressure caused by
accretion processes approximately halts the inflow of accreted material
- this is hard to calculate exactly, but will be very small compared to
the Earth's diameter of 6000 km.
>
>"At 20 km/s, the black hole's gravity will indeed exceed the Earth's
> locally for 30 seconds or so."
>
>At what distance? Define "locally". What about gradients? Tidal? Twit.
>
That's pretty obvious, you fuckwit. At a tenth of the earth's mass, the
gravitational pull of the black hole will equal that of the Earth when
it reaches a distance of about 2000 km. When it gets much closer than
this, unsecured objects will sail off in its direction.
Perhaps you can elaborate on what - if anything - you mean by the rest
of your jabbering. Do you think that just because we are discussing the
effects of a black hole, the word "locally" must refer to relativistic
issues, rather than its ordinary meaning of "nearby"?
>You pontificate with absolute conviction yet do not support with math. You
>fuck up nomenclature and you state properties that you make up.
>I put it to you to devote the time you spend making moronic multi-paragraph
>statements on learning some basic physics.
>
Varney, the reason you never post physics is because any time you have,
you have made your embarrassing ignorance obvious to all.
Unfortunately, your one-line insults are much less successful than you
imagine at concealing your incapacity. Don't try to punch above your
weight, you'll only get hurt.
- Gerry Quinn
Michael Varney
> In article <ZfTd7.320$Oz3.1...@news.uswest.net>, "Michael Varney"
<mva...@muswest.net> wrote:
> >
> >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> >news:AGNd7.1162$s5.2...@news.indigo.ie...
> >> In article <sBBd7.326$Z81.3...@news.uswest.net>, "Michael Varney"
> ><mva...@muswest.net> wrote:
> >> >> Well this is interesting, as the blackhole got close to earth you'll
> >> >> soon get to the point where the blackhole's gravity is stronger than
> >> >> the earth's as cows and people fly into it (remember more of a
> >> >> blackhole's mass is near it's "surface").
> >> >
> >> >*sigh*
> >> >
> >>
> >> At 20 km/s, the black hole's gravity will indeed exceed the Earth's
> >> locally for 30 seconds or so.
> >>
> >> Perhaps you should devote some of the time you spend making moronic
> >> one-line insults to learning some rudiments of physics.
> >
> >*sigh*
> >"more of a black hole's mass is near its surface"?
> >
> >*smirk*
> >
> >Ok. What surface?
> >How do you know?
> >What percentage? Prove this with numbers?
>
> A Newtonian approximation is the most suitable way to analyse the static
> gravitational effects being discussed,
They are not static.
> and in terms of this
> approximation the statement is entirely valid.
"More of a black holes mass is near its surface" is valid?
*smirk*
> Of course, one might
> require a more sophisticated metric for certain purposes, but none of
> them are relevant here. We could model frame-dragging as a
> perturbation of the Newtonian approximation, but at 20km/s, any
> gravitomagnetic effects will be insignificant in any case.
Prove it. I have yet to see any numbers or equations, only statements such
as:
"I believe that"
and
"what should happen is"
> He is quite
Referring to yourself in the third person, Quinn?
You were the person who made the bone headed comment about the distribution
of mass near the surface of the black hole.
> correct that cows and people will fly towards it, though they will
> probably reach only the accretion zone rather than the black hole
> proper.
What makes you think this? Show the math.
> In the metric appropriate to the Newtonian approximation, the black hole
> will have a Schwarzschild radius of less than a millimetre.
Do you even know what a metric is? Trekkian technobabble does not impress
me.
> The
> appropriate 'surface' will be at the radius where the pressure caused by
> accretion processes approximately halts the inflow of accreted material
What are you babbling about?
> - this is hard to calculate exactly, but will be very small compared to
> the Earth's diameter of 6000 km.
What are you babbling about?
> >
> >"At 20 km/s, the black hole's gravity will indeed exceed the Earth's
> > locally for 30 seconds or so."
> >
> >At what distance? Define "locally". What about gradients? Tidal? Twit.
> >
>
> That's pretty obvious, you fuckwit.
To you I doubt it.
> At a tenth of the earth's mass, the
> gravitational pull of the black hole will equal that of the Earth when
> it reaches a distance of about 2000 km. When it gets much closer than
> this, unsecured objects will sail off in its direction.
Unsecured objects where, dolt? Are you sure for "30 seconds"?
You still haveent defined locally.
> Perhaps you can elaborate on what - if anything - you mean by the rest
> of your jabbering.
I am not surprised that you know nothing of gradients or tidal forces. Your
problem obviously, not mine.
> Do you think that just because we are discussing the
> effects of a black hole, the word "locally" must refer to relativistic
> issues, rather than its ordinary meaning of "nearby"?
Yes. But also you have to define locally in Newtonian physics also.
Obviously you do not understand the concept of locality as it relates to
physics.
> >You pontificate with absolute conviction yet do not support with math.
You
> >fuck up nomenclature and you state properties that you make up.
> >I put it to you to devote the time you spend making moronic
multi-paragraph
> >statements on learning some basic physics.
> >
>
> Varney, the reason you never post physics is because any time you have,
> you have made your embarrassing ignorance obvious to all.
You seem to take the stance of many crackpots when called out on their
errors.
They make unsupported claims as to others abilities to comprehend physics in
an attempt to cover their own ignorance.
I belive it is even on the crackpot index.
Are you a crackpot Quinn? Well, are you?
Lets see you attempt some physics instead of spouting off babble.
> Don't try to punch above your
> weight, you'll only get hurt.
Take your own words to heart Quinn. It seems that you do not have much
training in physics. If you have you show a poor ability in applying it.
More mass near its surface indeed.
Again, I smirk at your humorous attempt to look like you know something.
However, it is very easy to see when someone faking knowledge about physics.
You cannot fake your way out of it Quinn.
Go play with the little kids in alt.sci.physics.
*smirk*
I...@te.spam
<mva...@muswest.net> wrote:
>
>"Gerry Quinn" <ger...@indigo.ie> wrote in message
>news:AGNd7.1162$s5.2...@news.indigo.ie...
>> In article <sBBd7.326$Z81.3...@news.uswest.net>, "Michael Varney"
><mva...@muswest.net> wrote:
>> >> Well this is interesting, as the blackhole got close to earth you'll
>> >> soon get to the point where the blackhole's gravity is stronger than
>> >> the earth's as cows and people fly into it (remember more of a
>> >> blackhole's mass is near it's "surface").
>> >
>> >*sigh*
>> >
>>
>> At 20 km/s, the black hole's gravity will indeed exceed the Earth's
>> locally for 30 seconds or so.
>>
>> Perhaps you should devote some of the time you spend making moronic
>> one-line insults to learning some rudiments of physics.
>
>*sigh*
>"more of a black hole's mass is near its surface"?
That's more like it!
>Ok. What surface?
Ok, as you notice I put surface in quotes, meaning I realize there is
no physical surface, but for this case the quick person would realize
what is meant by "surface" as the the event horizon "surface".
>How do you know?
Well as stated (thought not quoted) 1/10 Mass_earth blackhole would
have an event horizon radius of approximately 1mm, and since ALL of
the mass of a blackhole would be within the event horizon a bit of
logic should be all that is needed
>What percentage? Prove this with numbers?
Christ only going to be happy when you see actual equations and
numbers strewn about. Well I'm not going to do all the equations, but
I'll give you the equations and the numbers, and leave it to you to
find a calculator.
As for most of the blackhole mass is near the "surface" (or should I
say surface of the event horizon to make you happy?) R_s = 2GM/c^2,
use use some approximations of 6x10^-11 = G, 6x10^23 = M, 3x10^8 = c
You'll find the "surface" radius ~ 1mm. Now since all the mass is
within that, It'd be a quite safe bet to say 100% of that 1/10 Earth
mass is within 1mm of the "surface".
>"At 20 km/s, the black hole's gravity will indeed exceed the Earth's
> locally for 30 seconds or so."
>
>At what distance? Define "locally". What about gradients? Tidal? Twit.
I didn't state these numbers (basically because I didn't want to deal
with doing the math) but using just what is said there I'd say
"locally" means along the path of movement of the blackhole. Since
it's ~ 1mm you probably could consider it a point object. As what
distance, how about you stop calling people names, and use some
intelligence which you are apparently claiming to possess, lets see
you're given a velocity, and a time, and neglecting the "falling"
acceleration you can get a rough estimate of distance.
Yes even making a wrong approximation of close to the surface of the
earth, .5gt^2 + v_0t v_0t >> .5gt^2 within that 30 second time
frame, so can do a decent approximation of constant velocity, and get
any approximation you want.
>You pontificate with absolute conviction yet do not support with math. You
>fuck up nomenclature and you state properties that you make up.
>I put it to you to devote the time you spend making moronic multi-paragraph
>statements on learning some basic physics.
umm, yah, lesse mentioned a surface, which you didn't get to
understand "surface" of the event horizon. And a point where
F_gblackhole > F_gearthsurface. Which using a newtonian
approximation can easily be achieved by finding that Distance from
blackhole = (1/sqrt(10) ) * radius of earth
And since you're going to bitch about math and basic physics again
1g = GM_earth/r_earth^2 = GM_earth/10 * distance^2 (approximate
blackhole as a point mass due 1mm radius and distance at which we'll
find out where 1g is).
Cancel G & M_earth, and clean up to have
10*distance^2 = radius of earth^2
hence distance = (1/sqrt 10) radius of earth ~ 1/3 Earth radius
Earth radius is ~ 6x10^6 meters, you'll see that's 2x10^6 meters when
the gravity will cancel (granted this is an APPROXIMATION, but good
enough for something as simple as a thought idea).
granted, whomever posted the 30seconds of weightlessness is off by 30
seconds, but it's within such a factor that it doesn't really dictate
a verbal slashing, and maybe a "check your numbers you're off by a
factor of 10" response at best.
>
>
Michael Varney
<I...@te.spam> wrote in message
news:h2ggntga7kkbalr0i...@4ax.com...
> On Mon, 13 Aug 2001 10:29:38 -0600, "Michael Varney"
> <mva...@muswest.net> wrote:
>
> >
> >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> >news:AGNd7.1162$s5.2...@news.indigo.ie...
> >> In article <sBBd7.326$Z81.3...@news.uswest.net>, "Michael Varney"
> ><mva...@muswest.net> wrote:
> >> >> Well this is interesting, as the blackhole got close to earth you'll
> >> >> soon get to the point where the blackhole's gravity is stronger than
> >> >> the earth's as cows and people fly into it (remember more of a
> >> >> blackhole's mass is near it's "surface").
> >> >
> >> >*sigh*
> >> >
> >>
> >> At 20 km/s, the black hole's gravity will indeed exceed the Earth's
> >> locally for 30 seconds or so.
> >>
> >> Perhaps you should devote some of the time you spend making moronic
> >> one-line insults to learning some rudiments of physics.
> >
> >*sigh*
> >"more of a black hole's mass is near its surface"?
> That's more like it!
*sigh*
Twit.
> >Ok. What surface?
>
> Ok, as you notice I put surface in quotes, meaning I realize there is
> no physical surface, but for this case the quick person would realize
> what is meant by "surface" as the the event horizon "surface".
So *smirk* you say that most of the mass of the black hole is located near
it's event horizon?
I reiterate:
*sigh*
> >How do you know?
> Well as stated (thought not quoted) 1/10 Mass_earth blackhole would
> have an event horizon radius of approximately 1mm, and since ALL of
> the mass of a blackhole would be within the event horizon a bit of
> logic should be all that is needed
I can see right here that you obviously have not studied much about black
holes.
Get MTW and start reading. Then when it gets above your level, please
donate this fine book to your local library where it will do someone more
worthy than you some good.
> >What percentage? Prove this with numbers?
> Christ only going to be happy when you see actual equations and
> numbers strewn about.
It is a good filter for 99% of cranks and crackpots:
> Well I'm not going to do all the equations,
No doubt.
> but
> I'll give you the equations and the numbers, and leave it to you to
> find a calculator.
> As for most of the blackhole mass is near the "surface" (or should I
> say surface of the event horizon to make you happy?) R_s = 2GM/c^2,
> use use some approximations of 6x10^-11 = G, 6x10^23 = M, 3x10^8 = c
> You'll find the "surface" radius ~ 1mm. Now since all the mass is
> within that, It'd be a quite safe bet to say 100% of that 1/10 Earth
> mass is within 1mm of the "surface".
Again with the ignorance. Chose your metric inside the event horizon. Play
around a bit and you will notice funny things happen to such concepts as
"length" as you approach the singularity. To say that most of the mass of a
black hole resides near its surface not only wrong, but highly misleading
and only shows the limits of your knowledge on the matter.
Oh well, you can't all have degrees in physics.
> >"At 20 km/s, the black hole's gravity will indeed exceed the Earth's
> > locally for 30 seconds or so."
> >
> >At what distance? Define "locally". What about gradients? Tidal? Twit.
> I didn't state these numbers (basically because I didn't want to deal
> with doing the math) but using just what is said there I'd say
> "locally" means along the path of movement of the blackhole. Since
> it's ~ 1mm you probably could consider it a point object. As what
> distance, how about you stop calling people names,
Why, twit?
> and use some
> intelligence which you are apparently claiming to possess,
Because I call you a twit has nothing to do with my intelligence.
> lets see
> you're given a velocity, and a time, and neglecting the "falling"
> acceleration you can get a rough estimate of distance.
> Yes even making a wrong approximation of close to the surface of the
> earth, .5gt^2 + v_0t v_0t >> .5gt^2 within that 30 second time
> frame, so can do a decent approximation of constant velocity, and get
> any approximation you want.
>
So that is how you get any number you wish. By oversimplification and
throwing out important information. Cool.
I bet when you forget the bun on the hamburgers you serve people really get
pissed.
> >You pontificate with absolute conviction yet do not support with math.
You
> >fuck up nomenclature and you state properties that you make up.
> >I put it to you to devote the time you spend making moronic
multi-paragraph
> >statements on learning some basic physics.
> umm, yah, lesse mentioned a surface, which you didn't get to
> understand "surface" of the event horizon.
Please work on your grammar as well as your spelling. Communication is a
large part of practicing physics.
I leave you with that last comment.
I...@te.spam
And thank you for that last comment Mr. Varney, I really hope you DO
make it your last comment, since it's very apparent you know
absolutely nothing about practicing physics.
Enjoy the silence.
Fuckwit
barrie.tite
<I...@te.spam> wrote in message
news:g7qgntg8nh75mikca...@4ax.com...
Don't sign yourself 'fuckwit', it will erode your self-esteem :-)
Barrie
Michael Varney
<I...@te.spam> wrote in message
news:g7qgntg8nh75mikca...@4ax.com...
> On Mon, 13 Aug 2001 17:18:56 -0600, "Michael Varney"
> <mva...@muswest.net> wrote:
>
> >
> >Please work on your grammar as well as your spelling. Communication is a
> >large part of practicing physics.
> >
> >I leave you with that last comment.
> >
> And thank you for that last comment Mr. Varney,
You are welcome.
> I really hope you DO
> make it your last comment, since it's very apparent you know
> absolutely nothing about practicing physics.
Defend your assertions, or can you crackpot?
And yes, you are a crackpot. I have looked at other posts of yours and it
is quite apparent that you know nothing, but still think you can contribute.
*smirk*
> Enjoy the silence.
>
> Fuckwit
That is an interesting signature, very appropriate for you I might add.
Michael Varney
"barrie.tite" <barri...@ntlworld.com> wrote in message
news:kb_d7.9287$v86.1...@news6-win.server.ntlworld.com...
:-D
Gerry Quinn
>"Gerry Quinn" <ger...@indigo.ie> wrote in message
>>
>> gravitational effects being discussed,
>
>They are not static.
20km per second is static, 0.00007c.
>
>> and in terms of this
>> approximation the statement is entirely valid.
>
>"More of a black holes mass is near its surface" is valid?
>*smirk*
In the metric of the classical analysis that is appropriate to this
problem, yes, all its mass is much less than 6000km from an
appropriately defined surface.
>
> > Of course, one might
>> require a more sophisticated metric for certain purposes, but none of
>> them are relevant here. We could model frame-dragging as a
>> perturbation of the Newtonian approximation, but at 20km/s, any
>> gravitomagnetic effects will be insignificant in any case.
>
>Prove it. I have yet to see any numbers or equations, only statements such
>as:
>"I believe that"
>and
>"what should happen is"
I haven't seen any from you, and clearly you have no concept of
the meaning of gravitomagnetism. But in any case, the situation, in
broad outline, is not difficult to analyse. We analyse the black hole
as a compact classical object, with a surface whose size is on the order
of metres or a bit larger. This surface is where the pressure generated
by heat emitted by accretion processes equals the gravitationally
induced pressure of the surrounding matter attracted towards the
slowly-moving black hole.
Calculating the exact radius of this surface, and the exact amount of
matter absorbed by the black hole, would be difficult, but not important
as regards the effect of a black hole of a tenth of the Earth's mass
passing through the Earth. The only important thing is the equation of
state of gravitationally compressed - and adiabatically expanding - core
material. The analysis is entirely classical.
A detailed analysis would not be easy, but one can very easily come up
with some ballpark figures. We first calculate the amount of rock
subjected to serious compression by the gravitational field of the black
hole, and the gravitational energy released. It's a bit more than I had
initially estimated. About a 1000 km sphere will be significantly
compressed. Assuming compression to half its volume, we get the
gravitational work done as about 5 x 10^29 J. (A detailed analysis
would involve estimating a pressure-density curve for core material -
I've done it the lazy way by assuming that gravitational acceleration to
a specified radius can be used instead of the pressure. For reasons I
won't go into, and which you wouldn't understand anyway, these figures
will be an overestimate.)
As the black hole passes, much of this energy will be recovered as the
core material expands like an ideal gas. The remainder will appear as
heat, and will also cause slowing of the black hole. However, the
energy will only be a fraction of the black hole's kinetic energy (2 x
10^31 J) and will not prevent it escaping the Earth.
By contrast, the comet's kinetic energy (the same amount, 2x10^31 J)
will be entirely converted into heat energy. Thus the comet will be
more than 100 times as devastating as the black hole. An moreaccurate
figure would probably be 1000 or perhaps even 10000 times.
Now Varley, I have purposely left gaps in this very brief and simple
analysis - I challenge you to do better, or admit yourself to be a
pusillanimous, arrogant moron. What do *you* think will happen when a
black hole, one-tenth the mass of the earth, and travelling at 20km/s,
hits us. Feel free to use general relativity, if you want to make an
ass of yourself.
>
>> He is quite
>
>Referring to yourself in the third person, Quinn?
>You were the person who made the bone headed comment about the distribution
>of mass near the surface of the black hole.
I wasn't - you just can't read. But it's not boneheaded anyway - in a
metric appropriate to the problem it is completely accurate.
>
>> correct that cows and people will fly towards it, though they will
>> probably reach only the accretion zone rather than the black hole
>> proper.
>
>What makes you think this? Show the math.
Material flowing relativistically towards the event horizon will only
amount to the equivalent of a 30m sphere of matter during the time
available for accretion. Since the temperature will counteract the
pressure effects, this is a generous (over)estimate of the maximum
amount of rock or other matter that can be absorbed by the black hole.
It is insignificant. Therefore flying cows will only reach the
accretion zone.
>
>> In the metric appropriate to the Newtonian approximation, the black hole
>> will have a Schwarzschild radius of less than a millimetre.
>
>Do you even know what a metric is? Trekkian technobabble does not impress
>me.
A metric isn't Trekkian technobabble. It's just a distance function.
When I say a black hole of a tenth of the Earth's mass has a radius of
less than a millimetre, I am using the everyday metric that corresponds
to the marks on everyday rulers. That's the metric that is appropriate
to this problem. In this metric, guess how far the mass of a black hole
is from its surface?
>
>> The
>> appropriate 'surface' will be at the radius where the pressure caused by
>> accretion processes approximately halts the inflow of accreted material
>
>What are you babbling about?
Can't you even understand this? What do *you* think a black hole
travelling through the Earth will look like?
>
>> - this is hard to calculate exactly, but will be very small compared to
>> the Earth's diameter of 6000 km.
>
>What are you babbling about?
I explained it clearly. The edge of the accretion zone, where infalling
matter starts to be repelled by the pressure created by the accretion
processes. It's very hard to actually fall into a black hole.
Astronomical ones have well-developed accretion disks, but I suspect the
accretion zone for a small black hole passing through a planet would be
messy.
>
>> >
>> >"At 20 km/s, the black hole's gravity will indeed exceed the Earth's
>> > locally for 30 seconds or so."
>> >
>> >At what distance? Define "locally". What about gradients? Tidal? Twit.
>> >
>> That's pretty obvious, you fuckwit.
>
>To you I doubt it.
>
>> At a tenth of the earth's mass, the
>> gravitational pull of the black hole will equal that of the Earth when
>> it reaches a distance of about 2000 km. When it gets much closer than
>> this, unsecured objects will sail off in its direction.
>
>Unsecured objects where, dolt? Are you sure for "30 seconds"?
>You still haveent defined locally.
>
Locally = nearby. If I am sitting in my study, I will find myself
becoming weightless when the black hole is 2000 km overhead, and nearby
unsecured (not tied to the floor - you need to buy a dictionary) objects
will experience the same.
Remaining drool deleted.
Okay Varley, let's see you analyse the effects of a black hole. (Not
that there's much hope of that.) I've given a ballpark figure for the
amount of energy released as it passes through, and I can show it's only
a small fraction of its total kinetic energy. Do you challenge these
figures? Is there some relativistic issue I have ignored that should be
included, and if so what is it?
Put up or shut up, you arrogant, smirking, ignorant loon.
- Gerry Quinn
RC
<mva...@muswest.net> writes
Shut up Varney. You are creating an incident where there is none. Gerry
Quinn and "I...@te.spam" are good posters.
--
Blow it out of your ass
http://www.earthpoetry.demon.co.uk
RC
Michael Varney
> In article <9l9fe2$em7$1...@peabody.colorado.edu>, "Michael Varney"
<var...@coloradospam.edu> wrote:
> >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> >>
> >> A Newtonian approximation is the most suitable way to analyse the
static
> >> gravitational effects being discussed,
> >
> >They are not static.
>
> 20km per second is static, 0.00007c.
*smirk*
<Rest deleted without reading>
Oh well. Go back to flipping hamburgers, or whatever you do, whilst I
prepare to for the class I am to teach in the fall.
Gerry Quinn
>
>"Gerry Quinn" <ger...@indigo.ie> wrote in message
>> >>
>> >> A Newtonian approximation is the most suitable way to analyse the
>static
>> >> gravitational effects being discussed,
>> >
>> >They are not static.
>>
>> 20km per second is static, 0.00007c.
>
>*smirk*
>
><Rest deleted without reading>
I was pretty sure you wouldn't have the courage to try to analyse the
situation yourself. Although your efforts would undoubtedly be
laughable, you would be less despised for trying. (And it would have
been funny to see you attempting the GR analysis you claim is
necessary.)
>
>Oh well. Go back to flipping hamburgers, or whatever you do, whilst I
>prepare to for the class I am to teach in the fall.
>
Even in your menial demonstrator's post (that is the best I can imagine;
in truth I had you pegged as some sort of mechanical technician) I pity
the students whose time you will waste with your incompetence.
But if this newsgroup is to be spared your inane and content-free
contributions, their suffering will be our gain.
- Gerry Quinn
Michael Varney
> In article <fPfe7.1512$E84.2...@news.uswest.net>, "Michael Varney"
<mva...@muswest.net> wrote:
> >
> >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> >news:Np9e7.1517$s5.2...@news.indigo.ie...
> >> >>
> >> >> A Newtonian approximation is the most suitable way to analyse the
> >static
> >> >> gravitational effects being discussed,
> >> >
> >> >They are not static.
> >>
> >> 20km per second is static, 0.00007c.
> >
> >*smirk*
> >
> ><Rest deleted without reading>
>
> I was pretty sure you wouldn't have the courage to try to analyse the
> situation yourself.
No, more of lack of respect for your abilities and the fact it is more fun
ridiculing you. You stated some patently false arguments, then started
foaming and backpedaling. Even if you have demonstrated some modicum of
physics skill, you have already tainted yourself in your behavior.
> Although your efforts would undoubtedly be
> laughable, you would be less despised for trying. (And it would have
> been funny to see you attempting the GR analysis you claim is
> necessary.)
Refusal to prove my abilities does not equal a lack of ability. I merely
have confidence in my ability and would rather apply them to teaching people
who are worthy of my time. You are not worthy of the time taken to teach
you. You have not shown yourself worthy for me to take any time learning
from you. My students are worthy of both.
> >
> >Oh well. Go back to flipping hamburgers, or whatever you do, whilst I
> >prepare to for the class I am to teach in the fall.
> >
>
> Even in your menial demonstrator's post (that is the best I can imagine;
> in truth I had you pegged as some sort of mechanical technician) I pity
> the students whose time you will waste with your incompetence.
I am sure they and I will learn much and come out better for the experience.
> But if this newsgroup is to be spared your inane and content-free
> contributions, their suffering will be our gain.
Oh, be assured that I will continue to ridicule people like yourself.
People have told me I have better things to do with my time, and they are
probably right. It may be a Quixotian battle to tease cranks and crackpots,
but it is fun. I could spend my time attempting to teach cranks, and suffer
the same ranting from cranks and crackpots, or I can give them a reason to
rant and rave. I feel better having given them a reason.
Gerry Quinn
>"Gerry Quinn" <ger...@indigo.ie> wrote in message
>>
>> situation yourself.
>
>No, more of lack of respect for your abilities and the fact it is more fun
>ridiculing you. You stated some patently false arguments, then started
>foaming and backpedaling. Even if you have demonstrated some modicum of
>physics skill, you have already tainted yourself in your behavior.
Name one of these false arguments. (I did sort of err at the start when
I said the black hole couples gravitationally whereas the comet couples
electromagnetically. Although this is true, it is the size of the
objects that really makes the difference, and I should have mentioned
that. Someone - not you, of course - later pointed that out.
The truth is, Varney, you have never demonstrated *any* ability other
than that of making moronic, content-free insults. I've made a
simple back of the envelope analysis, right or wrong, of the effects of
a black hole striking the Earth. You haven't, because you don't have a
clue where or how to start. The little you have said demonstrates that
you don't even know which physics book to open. And now you're running
away, as I knew you would.
>
>> Although your efforts would undoubtedly be
>> laughable, you would be less despised for trying. (And it would have
>> been funny to see you attempting the GR analysis you claim is
>> necessary.)
>
>Refusal to prove my abilities does not equal a lack of ability. I merely
>have confidence in my ability and would rather apply them to teaching people
>who are worthy of my time. You are not worthy of the time taken to teach
>you. You have not shown yourself worthy for me to take any time learning
>from you. My students are worthy of both.
Any student of yours will learn only how to recognise and ignore
ignorant and offensive morons. That is useful, but probably not what
they signed up for. [The above paragraph is amusing, though, because
it's so entirely typical of the low-grade crank you like to bait.
Psychologically, you are pretty transparent.]
- Gerry Quinn
Michael Varney
> In article <rHge7.1532$E84.2...@news.uswest.net>, "Michael Varney"
<mva...@muswest.net> wrote:
> >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> >>
> >> I was pretty sure you wouldn't have the courage to try to analyse the
> >> situation yourself.
> >
> >No, more of lack of respect for your abilities and the fact it is more
fun
> >ridiculing you. You stated some patently false arguments, then started
> >foaming and backpedaling. Even if you have demonstrated some modicum of
> >physics skill, you have already tainted yourself in your behavior.
>
> Name one of these false arguments. (I did sort of err at the start when
> I said the black hole couples gravitationally whereas the comet couples
> electromagnetically.
And that is enough. Brains farts are one thing, but sheesh.
> Although this is true, it is the size of the
> objects that really makes the difference, and I should have mentioned
> that. Someone - not you, of course - later pointed that out.
I have not problems with that.
> The truth is, Varney, you have never demonstrated *any* ability other
> than that of making moronic, content-free insults
See, here it goes.
You were the one that made the stupid comment on nearly all the mass of a
black hole lying near its surface.
I merely stated *sigh* and you went off. Even if you do have a modicum of
physics knowledge, that alone would cloud my appraisal of your abilities.
You fucked up, plain and simple.
> I've made a
> simple back of the envelope analysis, right or wrong, of the effects of
> a black hole striking the Earth.
That was fine also, you were the one that went balistic when I sighed about
a conceptual error.
> You haven't, because you don't have a
> clue where or how to start.
> The little you have said demonstrates that
> you don't even know which physics book to open.
Keep saying this all you want. I have taken several graduate courses on GR
and differential geometry. I went to a GR workshop at Caltech taught by
Thorn.
You make a boneheaded comment, that is fine. Wallow in your own ignorance.
I have made my errors in GR on the news groups, and people like Hillman or
Baez have corrected me, so I cannot claim to be an "expert". However the
chances are good that I am more knowlegable on the subject than you.
> And now you're running
> away, as I knew you would.
It is not called running away. As I stated before it is a lack of respect
for you and your abilities. You have already put forth the mindset of
stubbornness and unwillingness to learn. To show you anything is pointless
because you will not listen, but would rather argue.
And admit it. You have seen my treatment of cranks and crackpots, and found
offense. Therefore not matter how well reasoned I could be about the
subject, you would still not listen because you do not like my manners.
Your loss.
> >
> >> Although your efforts would undoubtedly be
> >> laughable, you would be less despised for trying. (And it would have
> >> been funny to see you attempting the GR analysis you claim is
> >> necessary.)
> >
> >Refusal to prove my abilities does not equal a lack of ability. I merely
> >have confidence in my ability and would rather apply them to teaching
people
> >who are worthy of my time. You are not worthy of the time taken to teach
> >you. You have not shown yourself worthy for me to take any time learning
> >from you. My students are worthy of both.
>
> Any student of yours will learn only how to recognise and ignore
> ignorant and offensive morons. That is useful, but probably not what
> they signed up for. [The above paragraph is amusing, though, because
> it's so entirely typical of the low-grade crank you like to bait.
> Psychologically, you are pretty transparent.]
Very well. If you feel so strongly about it, I will look at you post if it
will get you to stop crying.
I will be fair. What good points you have I will acknowledge, and when you
fuck up I will try to correct your misconceptions.
How about that?
Michael Varney
much that I just broke down and decided to give his comments a fair reading.
"Gerry Quinn" <ger...@indigo.ie> wrote in message
news:Np9e7.1517$s5.2...@news.indigo.ie...
> In article <9l9fe2$em7$1...@peabody.colorado.edu>, "Michael Varney"
<var...@coloradospam.edu> wrote:
> >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> >>
> >> A Newtonian approximation is the most suitable way to analyse the
static
> >> gravitational effects being discussed,
> >
> >They are not static.
>
> 20km per second is static, 0.00007c.
I guess you can use argument that "relatively" 20km is considered static.
However, see below.
> >
> >> and in terms of this
> >> approximation the statement is entirely valid.
> >
> >"More of a black holes mass is near its surface" is valid?
> >*smirk*
>
> In the metric of the classical analysis that is appropriate to this
> problem, yes, all its mass is much less than 6000km from an
> appropriately defined surface.
Why did you state 6000km the event horizon of a .1 Earth mass black hole?
Remember, this is what you stated:
"More of a black holes mass is near its surface"
This would imply, and is something you stated later as obvious, that "its"
surface was in fact the event horizon.
Please note that a singularity, where ALL the mass (that is not in free fall
between the event horizon and the singularity) of a black hole resides
according to current models, in a region a size at most the Planck length.
When dealing with a black hole, the metric for a spherically symmetric,
non-spinning uncharged body of large mass is the Schwarzschild metric, not a
"metric of classical analysis". Please note that the metric applies
externally to the surface of the massive object, but because a black hole
does not have a surface, we can apply the metric all the way down to zero
radius. r = 0.
Now since all the mass is concentrated to a zero radius, and thus a zero
volume, I can choose and an epsilon > 0 for a radius surrounding the
singularity and calculate a volume, and thus a density.
I can then divide the volume of the event horizon by the epsilon volume and
get an arbitrarily large number, or by inverting it an arbitrarily small
number. This would be the percentage of mass ratio for these two surfaces.
To say that more of the mass of a black hole is near its surface is wrong
for many reasons:
Would you state that most of the mass of a Hydrogen atom is near its Bohr
radius? No. (Well, you might).
The better terminology would have been to state that "most of the mass of a
black hole resides within its event horizon ("surface")
Finally, in the case of Schwarzschild class black holes, which applies very
well even to slowly spinning black holes, the singularity is calculated to
be a point. If you want to play with a classical approximation, remember
that external to a spherical Gaussian surface, the gravitational field of
any symmetric configuration of masses inside acts like all the mass is a
point mass. This results in a 1/r^2 field.
In this case even if you were correct that most of the mass of a black hole
is "near" its surface, it would make no difference in the analysis.
Therefore, the statement should have been retracted as very unspecific,
wrong, or at least inapplicable to the problem.
> >
> > > Of course, one might
> >> require a more sophisticated metric for certain purposes, but none of
> >> them are relevant here. We could model frame-dragging as a
> >> perturbation of the Newtonian approximation, but at 20km/s, any
> >> gravitomagnetic effects will be insignificant in any case.
They would not be for a rapidly spinning black hole of the Kerr metric. We
would have to deal with the ergosphere in this case. With some simplifying
assumptions of the Kerr metric expressed standard in Boyer-Lindquist
coordinates, we can derive a useful equation for the "point of no return":
R^2 = r^2 + M^2 +2M^3 / r and is the extremal Kerr solution.
This is the equation that leads to frame dragging, or "gravitomagnetic
effects".
Play with the equations and you will get a static limit rs that is greater
than the event horizon. Everything will be "pulled" in the direction of the
spin of the black hole. Varying the mass and the angular velocity will
determine the extend of the ergosphere.
But since I concede (if you will) that we are dealing with a non-spinning,
uncharged spherically symmetric black hole, the effects will be negligible.
> >Prove it. I have yet to see any numbers or equations, only statements
such
> >as:
> >"I believe that"
> >and
> >"what should happen is"
>
> I haven't seen any from you, and clearly you have no concept of
> the meaning of gravitomagnetism.
Discussed above in layman's terms just for you.
> But in any case, the situation, in
> broad outline, is not difficult to analyse. We analyse the black hole
> as a compact classical object, with a surface whose size is on the order
> of metres or a bit larger.
This would not be a correct assumption, especially for a .1 Earth mass black
hole.
Not only that, but a surface cannot be a size of meters, but of square
meters. However, I will assume that this is just a typo rather than a lack
of understanding and assume that you mean that "the surface is at a radius
on the order of meters or a bit larger"
The radius of a black hole can be calculated by by Newtonian physics, and
leads to the correct equation for the radius of a black hole.
However, the interpritation of the Newtonian derivation states that any
object, no matter how fast (up to the speed of light) it is launched will
"fall" back to the surface. This means the particle will rise to some
radial distance before falling back down.
In GR the physics state that light or anything else launched at the event
horizon will never increase its radial position.
In any event, the result for a Schwarzschild black hole's event horizon is:
r = 2M where r is the reduced circumference.
For the mass of the Earth:
M = 4.44E-3 meters
Therefore r = 8.88 cm
And for a 0.1 Earth Mass black hole:
r = 8.88mm
I point out to you that in another post you stated that:
"In the metric appropriate to the Newtonian approximation, the black hole
will have a Schwarzschild radius of less than a millimetre."
Which is wrong, of course.
> This surface is where the pressure generated
> by heat emitted by accretion processes equals the gravitationally
> induced pressure of the surrounding matter attracted towards the
> slowly-moving black hole.
> Calculating the exact radius of this surface, and the exact amount of
> matter absorbed by the black hole, would be difficult, but not important
> as regards the effect of a black hole of a tenth of the Earth's mass
> passing through the Earth. The only important thing is the equation of
> state of gravitationally compressed - and adiabatically expanding - core
> material. The analysis is entirely classical.
Not entirely classical, but you are correct in that it is difficult to model
exactly.
Shakura and Sunyaev played with thin disk models in the Kerr metric.
> A detailed analysis would not be easy, but one can very easily come up
> with some ballpark figures. We first calculate the amount of rock
> subjected to serious compression by the gravitational field of the black
> hole, and the gravitational energy released. It's a bit more than I had
> initially estimated. About a 1000 km sphere will be significantly
> compressed. Assuming compression to half its volume, we get the
> gravitational work done as about 5 x 10^29 J.
Perhaps you should check your numbers:
Gravitational self energy of a uniform sphere of mass M and radius R is:
E=-3/5 (GM^2)/R
Using your assumption of compressiblity.
For a sphere of "rock" 1000km in radius and assuming a density of 3000
kg/m^3 we get a mass of M=12E21 kg
Assembled from infinty to R = 1000km:
E1 = 5.8E27 J
Assembled from infinity to R = 500km
E2 = 1.2E28 J
E2-E1 = 6x10^27 J
Compressional energies of the black hole, if given enough time would be much
larger of course.
(A detailed analysis
> would involve estimating a pressure-density curve for core material -
> I've done it the lazy way by assuming that gravitational acceleration to
> a specified radius can be used instead of the pressure.
And you did it wrong of course.
> For reasons I
> won't go into, and which you wouldn't understand anyway, these figures
> will be an overestimate.)
More than likely you guesstemated order of magnitude, hooked your finger and
fished some numbers out of your ass. You are right, I don't understand why
you would fish numbers out your ass since a first approximation answer is
trivial to compute.
>
> As the black hole passes, much of this energy will be recovered as the
> core material expands like an ideal gas. The remainder will appear as
> heat, and will also cause slowing of the black hole.
*sigh*
If core material expands like an ideal gas, it would be symmetric in all
directions. This would not slow the free space black hole unless the
ejected material were a jet in the direction of travel. This is basic
physics 101 here.
Fluctuatutions in density and distribution would lead to a non symmentrical
expuslion of matter that will change the velocity of the black hole
randomly.
If it is passing though the Earth, the black hole would be significantly
slowed down if its accretion surface was 500km in radius. Processes would
include bond breaking energy of the "rock" in the crust, mantel and core.
Degeneracy of the compressed material. Friction. Etc. In fact, there is a
good chance that the black hole would be captured inside the crust, or at
least captured in a harmonic motion where it passed multiple times before
being caught in the crust. This would be devastating to the planet for
obvious reasons.
> However, the
> energy will only be a fraction of the black hole's kinetic energy (2 x
> 10^31 J) and will not prevent it escaping the Earth.
KE = 1/2 M v^2
M= Mbh + Mrock = 6E24kg + 12E21kg =6.012E24 kg = 6E24 kg
v=20km/s
KE = 1.2E33 J
Again, check your numbers.
> By contrast, the comet's kinetic energy (the same amount, 2x10^31 J)
Where did you get this number?
> will be entirely converted into heat energy. Thus the comet will be
> more than 100 times as devastating as the black hole. An moreaccurate
> figure would probably be 1000 or perhaps even 10000 times.
Faulty logic, faulty physics.
The "expanding gas" of the accretion shell of "rock" has to dump its energy
somewhere. The energy would be dumped into the crust, mantel and core of the
planet as it passed through. Check above.
The best you could hope for would be the same amount of damage.
> Now Varley,
That's Varney. Have I misspelled you name?
> I have purposely left gaps in this very brief and simple
> analysis
Of course, what else is expected at your level?
>- I challenge you to do better,
I did, I could and at least I got the math correct.
> or admit yourself to be a
> pusillanimous
That is your opinion, not mine.
>, arrogant
I will admit to that.
> moron.
Hardly.
> What do *you* think will happen when a
> black hole, one-tenth the mass of the earth, and travelling at 20km/s,
> hits us.
As stated above:
However, even before the black hole struck there would be a massive tidal
force given by:
F = Constant GmM L(1/D^3)
Where M is mass of the hole, D is your distance from its center and L is the
length of the body.
Of course this is just one component of the tidal force.
The black hole would have to be at about 3 times the Earth Moon distance to
exert the same tidal effects as the Moon exerts.
This distance is around 12E8 m.
In another post you said that you could even ignore the acceleration between
the black hole and call the speed "static".
The time it would take at 20km/s to reach the Earth would be a little less
than 17 hours. During this time the Earth would feel a tidal force at least
as great as that of the Moon and getting larger as the inverse cube of the
distance.
This would wreak havoc on the Earth in its own right.
Just another small effect you neglected.
> Feel free to use general relativity, if you want to make an
> ass of yourself.
>
> >
> >> He is quite
> >
> >Referring to yourself in the third person, Quinn?
> >You were the person who made the bone headed comment about the
distribution
> >of mass near the surface of the black hole.
>
> I wasn't - you just can't read. But it's not boneheaded anyway - in a
> metric appropriate to the problem it is completely accurate.
Already covered above.
> >
> >> correct that cows and people will fly towards it, though they will
> >> probably reach only the accretion zone rather than the black hole
> >> proper.
> >
> >What makes you think this? Show the math.
>
> Material flowing relativistically towards the event horizon will only
> amount to the equivalent of a 30m sphere of matter during the time
> available for accretion.
Again, did you pull this number out of your ass? I would bet that you did.
> Since the temperature will counteract the
> pressure effects, this is a generous (over)estimate of the maximum
> amount of rock or other matter that can be absorbed by the black hole.
Perhaps.
> It is insignificant. Therefore flying cows will only reach the
> accretion zone.
Ever?
> >
> >> In the metric appropriate to the Newtonian approximation, the black
hole
> >> will have a Schwarzschild radius of less than a millimetre.
> >
> >Do you even know what a metric is? Trekkian technobabble does not
impress
> >me.
Again please describe to me the properties of a metric. And also
recalculate your numbers.
> A metric isn't Trekkian technobabble.
The way you use it it is. Trekkian technobabble uses correct terms, but
incorrectly, inapplicably, out of context or with out real knowledge. It is
used by cranks to sound like they know what they are doing. this will fool
most people, but not a trained physicist.
> It's just a distance function.
No, it is not. The metric, in simplist terms in deferene to you Quinn, is
the seperation between events in spacetime.
> When I say a black hole of a tenth of the Earth's mass has a radius of
> less than a millimetre,
You are wrong.
> I am using the everyday metric that corresponds
> to the marks on everyday rulers.
Even in a flat space time a metric is not "a distance function".
> That's the metric that is appropriate
> to this problem.
If you state that "a distance function" is a proper metric for this problem,
no wonder you consider 20km/s "static" *smirk*
> In this metric, guess how far the mass of a black hole
> is from its surface?
Already covered above.
> >
> >> The
> >> appropriate 'surface' will be at the radius where the pressure caused
by
> >> accretion processes approximately halts the inflow of accreted material
> >
> >What are you babbling about?
I withdraw this comment.
> Can't you even understand this? What do *you* think a black hole
> travelling through the Earth will look like?
>
> >
> >> - this is hard to calculate exactly, but will be very small compared to
> >> the Earth's diameter of 6000 km.
> >
> >What are you babbling about?
I withdraw that comment.
> I explained it clearly. The edge of the accretion zone, where infalling
> matter starts to be repelled by the pressure created by the accretion
> processes. It's very hard to actually fall into a black hole.
No, it is not.
> Astronomical ones have well-developed accretion disks,
In the Kerr metric, which you have not covered.
> but I suspect the
> accretion zone for a small black hole passing through a planet would be
> messy.
http://ttt.lanl.gov/PS_cache/astro-ph/pdf/9908/9908185.pdf
> >
> >> >
> >> >"At 20 km/s, the black hole's gravity will indeed exceed the Earth's
> >> > locally for 30 seconds or so."
> >> >
> >> >At what distance? Define "locally". What about gradients? Tidal?
Twit.
> >> >
> >> That's pretty obvious, you fuckwit.
> >
> >To you I doubt it.
> >
> >> At a tenth of the earth's mass, the
> >> gravitational pull of the black hole will equal that of the Earth when
> >> it reaches a distance of about 2000 km
>. When it gets much closer than
> >> this, unsecured objects will sail off in its direction.
> >
> >Unsecured objects where, dolt? Are you sure for "30 seconds"?
> >You still haveent defined locally.
> >
>
> Locally = nearby.
No a proper definition in SR or GR.
> If I am sitting in my study, I will find myself
> becoming weightless when the black hole is 2000 km overhead, and nearby
> unsecured (not tied to the floor - you need to buy a dictionary) objects
> will experience the same.
Ok.
And this will happen for over 2 min.
> Remaining drool deleted.
>
> Okay Varley
Ok Savian.
> let's see you analyse the effects of a black hole.
See above.
> (Not
> that there's much hope of that.) I've given a ballpark figure for the
> amount of energy released as it passes through,
And even if your physics were correct, your numbers were not.
> and I can show it's only
> a small fraction of its total kinetic energy. Do you challenge these
> figures?
Yes, as shown above, and trivially so.
> Is there some relativistic issue I have ignored that should be
> included, and if so what is it?
Discussed above.
> Put up or shut up, you arrogant, smirking, ignorant loon.
Arrogant and smirking loon, yes. Ignorant, in some matters yes.
However, while I might be ignorant, you are just plain stupid. Ignorance
can be cured, stupidity cannot.
Michael Varney
"Michael Varney" <mva...@muswest.net> wrote in message
news:JeBe7.1927$kH1.4...@news.uswest.net...
> Here is my analysis of the comments of Quinn. He was crying and whining
so
> much that I just broke down and decided to give his comments a fair
reading.
>
> "Gerry Quinn" <ger...@indigo.ie> wrote in message
> news:Np9e7.1517$s5.2...@news.indigo.ie...
> > In article <9l9fe2$em7$1...@peabody.colorado.edu>, "Michael Varney"
> <var...@coloradospam.edu> wrote:
> > >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> > >>
>
> > However, the
> > energy will only be a fraction of the black hole's kinetic energy (2 x
> > 10^31 J) and will not prevent it escaping the Earth.
>
> KE = 1/2 M v^2
>
> M= Mbh + Mrock = 6E24kg + 12E21kg =6.012E24 kg = 6E24 kg
Correction: Mbh = 0.6E24 kg in this problem.
> v=20km/s
>
> KE = 1.2E33 J
Correction: 1.2E32 J
Martin Brown
Michael Varney wrote:
> "Gerry Quinn" <ger...@indigo.ie> wrote in message
> news:Np9e7.1517$s5.2...@news.indigo.ie...
> > In article <9l9fe2$em7$1...@peabody.colorado.edu>, "Michael Varney"
> <var...@coloradospam.edu> wrote:
> > >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> > >> require a more sophisticated metric for certain purposes, but none of
> > >> them are relevant here. We could model frame-dragging as a
> > >> perturbation of the Newtonian approximation, but at 20km/s, any
> > >> gravitomagnetic effects will be insignificant in any case.
>
> They would not be for a rapidly spinning black hole of the Kerr metric. We
> would have to deal with the ergosphere in this case. With some simplifying
> assumptions of the Kerr metric expressed standard in Boyer-Lindquist
> coordinates, we can derive a useful equation for the "point of no return":
>
> R^2 = r^2 + M^2 +2M^3 / r and is the extremal Kerr solution.
>
> This is the equation that leads to frame dragging, or "gravitomagnetic
> effects".
> Play with the equations and you will get a static limit rs that is greater
> than the event horizon. Everything will be "pulled" in the direction of the
> spin of the black hole. Varying the mass and the angular velocity will
> determine the extend of the ergosphere.
>
> But since I concede (if you will) that we are dealing with a non-spinning,
> uncharged spherically symmetric black hole, the effects will be negligible.
I was hoping someone would be able to provide a guesstimate of the extent to
which the black hole might choke on such dense material as it goes through the
core. Estimates have been done in an astrophysical context for an accretion disk
of plasma, but AFAIK nothing exists for BH hits solid rock or molten iron. See
for example Stone, Pringle & Begelman online at ADS and briefly at:
http://www.ast.cam.ac.uk/frontpages/jep/
It would be interesting to ponder how much extra damage a Kerr metric BH would
do by generating bipolar axial flows. But Schwarzchild metric is OK for the
basics.
> In any event, the result for a Schwarzschild black hole's event horizon is:
>
> r = 2M where r is the reduced circumference.
>
> For the mass of the Earth:
> M = 4.44E-3 meters
> Therefore r = 8.88 cm
>
> And for a 0.1 Earth Mass black hole:
> r = 8.88mm
>
> I point out to you that in another post you stated that:
>
> "In the metric appropriate to the Newtonian approximation, the black hole
> will have a Schwarzschild radius of less than a millimetre."
>
> Which is wrong, of course.
No. It is you who are wrong. And you are very graceless about it too.
Every one else on the planet can see that 2 x 4.44E-3 m = 8.88mm
I'd be content with numbers estimated to the nearest power of ten anyway.
There are far too many gross approximations needed for the interaction of
rock/iron core with a BH to worry about small leading constants of O(1).
> > This surface is where the pressure generated
> > by heat emitted by accretion processes equals the gravitationally
> > induced pressure of the surrounding matter attracted towards the
> > slowly-moving black hole.
> > Calculating the exact radius of this surface, and the exact amount of
> > matter absorbed by the black hole, would be difficult, but not important
> > as regards the effect of a black hole of a tenth of the Earth's mass
> > passing through the Earth. The only important thing is the equation of
> > state of gravitationally compressed - and adiabatically expanding - core
> > material. The analysis is entirely classical.
>
> Not entirely classical, but you are correct in that it is difficult to model
> exactly.
> Shakura and Sunyaev played with thin disk models in the Kerr metric.
Others have dealt with more complex cases. The difficulty here is that AFAIK
noone has bothered to work through the effects of a BH moving through a planet.
It isn't a particularly likely scenario except in Hollywood movies and BBC
"science" programmes.
> > As the black hole passes, much of this energy will be recovered as the
> > core material expands like an ideal gas. The remainder will appear as
> > heat, and will also cause slowing of the black hole.
>
> *sigh*
>
> If core material expands like an ideal gas, it would be symmetric in all
> directions. This would not slow the free space black hole unless the
> ejected material were a jet in the direction of travel. This is basic
> physics 101 here.
Compressing and heating the material in front of it must come at the expense of
a slight loss of KE (and momentum). However, it seems that for modest sizes of
BH there is little chance of the amount a matter accreted going through a planet
halting it or even slowing it significantly.
> If it is passing though the Earth, the black hole would be significantly
> slowed down if its accretion surface was 500km in radius. Processes would
> include bond breaking energy of the "rock" in the crust, mantel and core.
> Degeneracy of the compressed material. Friction. Etc. In fact, there is a
> good chance that the black hole would be captured inside the crust, or at
> least captured in a harmonic motion where it passed multiple times before
> being caught in the crust. This would be devastating to the planet for
> obvious reasons.
This doesn't sound right. Lets see your numbers. An object with that size of
accretion surface would have to be so massive that it would not make any
significant difference to it's momentum.
> > will be entirely converted into heat energy. Thus the comet will be
> > more than 100 times as devastating as the black hole. An moreaccurate
> > figure would probably be 1000 or perhaps even 10000 times.
>
> Faulty logic, faulty physics.
> The "expanding gas" of the accretion shell of "rock" has to dump its energy
> somewhere. The energy would be dumped into the crust, mantel and core of the
> planet as it passed through. Check above.
> The best you could hope for would be the same amount of damage.
I don't think so, but I am open to being convinced otherwise by a reasoned
argument.
> > but I suspect the
> > accretion zone for a small black hole passing through a planet would be
> > messy.
>
> http://ttt.lanl.gov/PS_cache/astro-ph/pdf/9908/9908185.pdf
That's the original paper of SP&B I referred to above. If anything their results
imply that accretion into the black hole will be largely choked off during its
passage through the Earth.
Black holes it seems choke on excessively rich food.
Regards,
Martin Brown
Florian
Yabbbering.idiots
You will both do well there, and please from now on, stay a (little)
focused on the subject of the news group, cause i am quite irritated to
spend my time reading this kind of nonsense.
Regards Florian
Gerry Quinn
>
>"Gerry Quinn" <ger...@indigo.ie> wrote in message
>
>> than that of making moronic, content-free insults
>
>See, here it goes.
>You were the one that made the stupid comment on nearly all the mass of a
>black hole lying near its surface.
>I merely stated *sigh* and you went off. Even if you do have a modicum of
>physics knowledge, that alone would cloud my appraisal of your abilities.
>You fucked up, plain and simple.
>
Others will find their estimates of your abilities considerably more
clouded, because in fact it was "IH@teSpam" who made the statement.
Evidently you are semi-literate in English as in physics.
I did point out, however, that in the appropriate (classical) metric the
statement is perfectly correct. One can approach the Earth's centre of
mass only within a distance of about 6000km. The devastating effects of
a black hole occur because other matter can come very much closer to its
centre of mass.
>> I've made a
>> simple back of the envelope analysis, right or wrong, of the effects of
>> a black hole striking the Earth.
>
>That was fine also, you were the one that went balistic when I sighed about
>a conceptual error.
Varney, I have utter contempt for you and the meaningless pointless
interjections you post. I just want you to keep your crap away from
threads on which I participate. I would prefer if you kept it away from
all threads.
>
>> You haven't, because you don't have a
>> clue where or how to start.
>> The little you have said demonstrates that
>> you don't even know which physics book to open.
>
>Keep saying this all you want. I have taken several graduate courses on GR
>and differential geometry. I went to a GR workshop at Caltech taught by
>Thorn.
>You make a boneheaded comment, that is fine. Wallow in your own ignorance.
>I have made my errors in GR on the news groups, and people like Hillman or
>Baez have corrected me, so I cannot claim to be an "expert". However the
>chances are good that I am more knowlegable on the subject than you.
And this is not a problem that requires GR, you imbecile. As I said,
you don't even have a clue which book to open.
>
>> And now you're running
>> away, as I knew you would.
>
>It is not called running away. As I stated before it is a lack of respect
>for you and your abilities. You have already put forth the mindset of
>stubbornness and unwillingness to learn. To show you anything is pointless
>because you will not listen, but would rather argue.
>And admit it. You have seen my treatment of cranks and crackpots, and found
>offense. Therefore not matter how well reasoned I could be about the
>subject, you would still not listen because you do not like my manners.
>Your loss.
But you've never, in my observation, contributed anything to this or any
other newsgroup. What could I ever learn from you, except how to be an
offensive moron?
>
>> >
>> >> Although your efforts would undoubtedly be
>> >> laughable, you would be less despised for trying. (And it would have
>> >> been funny to see you attempting the GR analysis you claim is
>> >> necessary.)
>> >
>> >Refusal to prove my abilities does not equal a lack of ability. I merely
>> >have confidence in my ability and would rather apply them to teaching
>people
>> >who are worthy of my time. You are not worthy of the time taken to teach
>> >you. You have not shown yourself worthy for me to take any time learning
>> >from you. My students are worthy of both.
>>
>> Any student of yours will learn only how to recognise and ignore
>> ignorant and offensive morons. That is useful, but probably not what
>> they signed up for. [The above paragraph is amusing, though, because
>> it's so entirely typical of the low-grade crank you like to bait.
>> Psychologically, you are pretty transparent.]
>
>Very well. If you feel so strongly about it, I will look at you post if it
>will get you to stop crying.
>I will be fair. What good points you have I will acknowledge, and when you
>fuck up I will try to correct your misconceptions.
>How about that?
>
Fine. I will look forward to your estimate of the effects of a black
hole, though, rather than the rather too easy task of finding
imperfections in my analysis.
- Gerry Quinn
Gerry Quinn
Feel free to post your own analysis of the effects of a black hole. I
see Varney has now made some sort of attempt thereon, which should be
amusing...
- Gerry Quinn
Michael Varney
> In article <C6ye7.1388$kH1.2...@news.uswest.net>, "Michael Varney"
<mva...@muswest.net> wrote:
> >
> >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> >
> >> The truth is, Varney, you have never demonstrated *any* ability other
> >> than that of making moronic, content-free insults
> >
> >See, here it goes.
> >You were the one that made the stupid comment on nearly all the mass of a
> >black hole lying near its surface.
> >I merely stated *sigh* and you went off. Even if you do have a modicum
of
> >physics knowledge, that alone would cloud my appraisal of your abilities.
> >You fucked up, plain and simple.
> >
>
> Others will find their estimates of your abilities considerably more
> clouded, because in fact it was "IH@teSpam" who made the statement.
> Evidently you are semi-literate in English as in physics.
>
> I did point out, however, that in the appropriate (classical) metric the
> statement is perfectly correct.
*sigh*
Michael Varney
"Martin Brown" <martin...@pandora.be> wrote in message
news:3B7B7DCF...@pandora.be...
Yes. It would.
> > In any event, the result for a Schwarzschild black hole's event horizon
is:
> >
> > r = 2M where r is the reduced circumference.
> >
> > For the mass of the Earth:
> > M = 4.44E-3 meters
> > Therefore r = 8.88 cm
> >
> > And for a 0.1 Earth Mass black hole:
> > r = 8.88mm
> >
> > I point out to you that in another post you stated that:
> >
> > "In the metric appropriate to the Newtonian approximation, the black
hole
> > will have a Schwarzschild radius of less than a millimetre."
> >
> > Which is wrong, of course.
>
> No. It is you who are wrong. And you are very graceless about it too.
> Every one else on the planet can see that 2 x 4.44E-3 m = 8.88mm
Yes, the point was to see if Quinn actually checked his numbers, and that of
others. I tried to be obvious about it, but perhaps too obvious? I guess
Quinn is saved from having to think a little.
Oh well.
> I'd be content with numbers estimated to the nearest power of ten anyway.
> There are far too many gross approximations needed for the interaction of
> rock/iron core with a BH to worry about small leading constants of O(1).
Not counting, if we consider a Kerr metric, interactive effects with the
magnetic field of the planet, frame dragging, etc.
> > > This surface is where the pressure generated
> > > by heat emitted by accretion processes equals the gravitationally
> > > induced pressure of the surrounding matter attracted towards the
> > > slowly-moving black hole.
> > > Calculating the exact radius of this surface, and the exact amount of
> > > matter absorbed by the black hole, would be difficult, but not
important
> > > as regards the effect of a black hole of a tenth of the Earth's mass
> > > passing through the Earth. The only important thing is the equation
of
> > > state of gravitationally compressed - and adiabatically expanding -
core
> > > material. The analysis is entirely classical.
> >
> > Not entirely classical, but you are correct in that it is difficult to
model
> > exactly.
> > Shakura and Sunyaev played with thin disk models in the Kerr metric.
>
> Others have dealt with more complex cases. The difficulty here is that
AFAIK
> noone has bothered to work through the effects of a BH moving through a
planet.
There is a guy I know who Gregory Benford contacted with this sort of
problem for his book "The Eater", or was it "Artifact" that did some back of
the envelope calculations. I wonder what he would say about this.
> It isn't a particularly likely scenario except in Hollywood movies and BBC
> "science" programmes.
Or in science fiction novels. Or in the planets where it has undoubtedly
already happened.
> > > As the black hole passes, much of this energy will be recovered as the
> > > core material expands like an ideal gas. The remainder will appear as
> > > heat, and will also cause slowing of the black hole.
> >
> > *sigh*
> >
> > If core material expands like an ideal gas, it would be symmetric in all
> > directions. This would not slow the free space black hole unless the
> > ejected material were a jet in the direction of travel. This is basic
> > physics 101 here.
>
> Compressing and heating the material in front of it must come at the
expense of
> a slight loss of KE (and momentum). However, it seems that for modest
sizes of
> BH there is little chance of the amount a matter accreted going through a
planet
> halting it or even slowing it significantly.
Please note the words "free space". And note the paragraphs that you
snipped, which I assume you agree with.
> > If it is passing though the Earth, the black hole would be significantly
> > slowed down if its accretion surface was 500km in radius. Processes
would
> > include bond breaking energy of the "rock" in the crust, mantel and
core.
> > Degeneracy of the compressed material. Friction. Etc. In fact, there is
a
> > good chance that the black hole would be captured inside the crust, or
at
> > least captured in a harmonic motion where it passed multiple times
before
> > being caught in the crust. This would be devastating to the planet for
> > obvious reasons.
>
> This doesn't sound right. Lets see your numbers.
How about seeing your numbers? You have yet to offer any (beyond the
obvious). How about some of the physics?
You were hoping to read about effects of a black hole going through a planet
but were bummed that we did not enlighten you. How about you doing the
analysis and enlightening us?
> An object with that size of
> accretion surface would have to be so massive that it would not make any
> significant difference to it's momentum.
The accretion surface radius was not my number, but Quinn's. As was already
covered in my post was an indication that this sort of compaction of "rock"
around the hole was unlikely and a gross understatement.
> > > will be entirely converted into heat energy. Thus the comet will be
> > > more than 100 times as devastating as the black hole. An moreaccurate
> > > figure would probably be 1000 or perhaps even 10000 times.
> >
> > Faulty logic, faulty physics.
> > The "expanding gas" of the accretion shell of "rock" has to dump its
energy
> > somewhere. The energy would be dumped into the crust, mantel and core of
the
> > planet as it passed through. Check above.
> > The best you could hope for would be the same amount of damage.
>
> I don't think so, but I am open to being convinced otherwise by a reasoned
> argument.
Lets see.
A comet 0.1 Earths mass hits the Earth. Boom! Kinetic energy.
A BH 0.1 Earth's mass hits the Earth, accretes a 500km, radius shell of
rock, compacted from 1000 km shell (Quinn's numbers for whatever reason, not
mine) and hardly slowing down (your contention). Boom! Nearly the same KE.
If you read my paragraph closely, I stated that Quinn's physics were in
error. Such as the amount of accreted material, how much it gravitationally
compacted, etc.
So if you are not convinced, good, that was the point.
> > > but I suspect the
> > > accretion zone for a small black hole passing through a planet would
be
> > > messy.
> >
> > http://ttt.lanl.gov/PS_cache/astro-ph/pdf/9908/9908185.pdf
>
> That's the original paper of SP&B I referred to above. If anything their
results
> imply that accretion into the black hole will be largely choked off during
its
> passage through the Earth.
> Black holes it seems choke on excessively rich food.
So it would seem.
Gerry Quinn
>Here is my analysis of the comments of Quinn. He was crying and whining so
>much that I just broke down and decided to give his comments a fair reading.
>"Gerry Quinn" <ger...@indigo.ie> wrote in message
Varney's attempts at physics are as laughable as I predicted. I shall
deal with his more egregious blunders one by one.
>> >
>> >"More of a black holes mass is near its surface" is valid?
>> >*smirk*
>>
>> In the metric of the classical analysis that is appropriate to this
>> problem, yes, all its mass is much less than 6000km from an
>> appropriately defined surface.
>
>Why did you state 6000km the event horizon of a .1 Earth mass black hole?
Er, Michael, 6000km is the radius of the Earth.
>Remember, this is what you stated:
>"More of a black holes mass is near its surface"
IH@ateSpam stated this, making a comparison between a black hole and the
earth.
>This would imply, and is something you stated later as obvious, that "its"
>surface was in fact the event horizon.
Actually, an appropriate 'surface' would, as I stated, be the edge of
the accretion zone, where infalling matter is diverted to a considerable
extent from its inward fall. But either way, by any reasonable
definition of 'surface', it is small compared to the Earth's.
>Please note that a singularity, where ALL the mass (that is not in free fall
>between the event horizon and the singularity) of a black hole resides
>according to current models, in a region a size at most the Planck length.
I think you mean last century's models. Even in general relativity you
are blundering, though, because according to the instruments of any
hypothetical observers, the mass is 'frozen' and has not reached any
putative central singularity. [The central singularity concept is a bit
of a joke anyway, IMO, but that is irrelevant to the current debate.]
>When dealing with a black hole, the metric for a spherically symmetric,
>non-spinning uncharged body of large mass is the Schwarzschild metric, not a
>"metric of classical analysis".
But we are dealing with a black hole and a planet, and I am using the
metric of the planet. Which to all intents and purposes is flat.
Indeed, I analyse the black hole as a compact classical object, so talk
of metrics doesn't really come into it.
>I can then divide the volume of the event horizon by the epsilon volume and
>get an arbitrarily large number, or by inverting it an arbitrarily small
>number. This would be the percentage of mass ratio for these two surfaces.
>To say that more of the mass of a black hole is near its surface is wrong
>for many reasons:
>Would you state that most of the mass of a Hydrogen atom is near its Bohr
>radius? No. (Well, you might).
>
If I were comparing the gravitational effects of a hydrogen atom to
those of an apple, I certainly would. Remember, the original poster was
talking of the effects on 'cows and people'. Thus the appropriate
meaning of "near" is simple distance, not any ratio. But I shall pass
on. Your errors here are funny, but unimportant.
>> > > Of course, one might
>> >> require a more sophisticated metric for certain purposes, but none of
>> >> them are relevant here. We could model frame-dragging as a
>> >> perturbation of the Newtonian approximation, but at 20km/s, any
>> >> gravitomagnetic effects will be insignificant in any case.
>
>They would not be for a rapidly spinning black hole of the Kerr metric. [--]
>
>But since I concede (if you will) that we are dealing with a non-spinning,
>uncharged spherically symmetric black hole, the effects will be negligible.
>>
>> I haven't seen any from you, and clearly you have no concept of
>> the meaning of gravitomagnetism.
>
>Discussed above in layman's terms just for you.
Given that you concede that my statement was correct, your discussion is
clearly unnecessary as well as irrelevant. It's true that if a lot of
the black hole's energy was rotational (but to an astronomcally
plausible degree, not an extremal Kerr hole), this energy would increase
the energy released close to the black hole. That won't really make a
lot of difference to the effects, though. The energy release will
nearly all come from an inelastic gravitational interaction with the
Earth - that's why relativity, special or general, is basically
irrelevant except for calculating the amount of accretion. And for
that, "small" is good enough.
>
>> But in any case, the situation, in
>> broad outline, is not difficult to analyse. We analyse the black hole
>> as a compact classical object, with a surface whose size is on the order
>> of metres or a bit larger.
>
>This would not be a correct assumption, especially for a .1 Earth mass black
>hole.
>The radius of a black hole can be calculated by by Newtonian physics, and
>leads to the correct equation for the radius of a black hole.
>In any event, the result for a Schwarzschild black hole's event horizon is:
>r = 2M where r is the reduced circumference.
>And for a 0.1 Earth Mass black hole:
>r = 8.88mm
As I state below, the appropriate definition of 'surface' is nothing to
do with the event horizon. Just like the Earth's surface, it's the
region in which objects falling in are diverted from their path. This
will probably be at a radius of metres. (It certainly won't be anything
like the nonsensical 500km you come up with later...)
>
>I point out to you that in another post you stated that:
>"In the metric appropriate to the Newtonian approximation, the black hole
>will have a Schwarzschild radius of less than a millimetre."
>Which is wrong, of course.
Yes, I accidentally dropped a factor of ten.
>> This surface is where the pressure generated
>> by heat emitted by accretion processes equals the gravitationally
>> induced pressure of the surrounding matter attracted towards the
>> slowly-moving black hole.
>> Calculating the exact radius of this surface, and the exact amount of
>> matter absorbed by the black hole, would be difficult, but not important
>> as regards the effect of a black hole of a tenth of the Earth's mass
>> passing through the Earth. The only important thing is the equation of
>> state of gravitationally compressed - and adiabatically expanding - core
>> material. The analysis is entirely classical.
>
>Not entirely classical, but you are correct in that it is difficult to model
>exactly.
>Shakura and Sunyaev played with thin disk models in the Kerr metric.
It is entirely classical. I used nothing but Newtonian gravity.
>
>> A detailed analysis would not be easy, but one can very easily come up
>> with some ballpark figures. We first calculate the amount of rock
>> subjected to serious compression by the gravitational field of the black
>> hole, and the gravitational energy released. It's a bit more than I had
>> initially estimated. About a 1000 km sphere will be significantly
>> compressed. Assuming compression to half its volume, we get the
>> gravitational work done as about 5 x 10^29 J.
>
>Perhaps you should check your numbers:
>Gravitational self energy of a uniform sphere of mass M and radius R is:
>E=-3/5 (GM^2)/R
>Using your assumption of compressiblity.
>For a sphere of "rock" 1000km in radius and assuming a density of 3000
>kg/m^3 we get a mass of M=12E21 kg
>Assembled from infinty to R = 1000km:
>E1 = 5.8E27 J
>Assembled from infinity to R = 500km
>E2 = 1.2E28 J
>E2-E1 = 6x10^27 J
This is the first of two blunders, either of which, taken on its own,
would prove your incompetence to match your arrogance. Have you
forgotten that there is a ***black hole*** at the centre of this ball of
rock? (Of course it's really a tube, I used a 1000km ball because it's
easy to calculate that 1000km or so is the distance at which a
free-falling object could fall all the way in to the black hole in the
time available. So it's a convenient guesstimate of the amount of rock
that's going to be compressed.)
I did a proper calculation, instead of the "fall half-way under constant
gravity" that gave me the figure above. The correct figure is 1.4x10^30
J, three times larger than I had. But *three hundred* times greater
than the figure you got. Poor boy, the textbook only gave one equation
so you had to use that even though it was totally inappropriate. (If
you had had the wit, you could have multiplied by the ratio of the mass
of the black hole to that of your sphere of rock. That would reduce
your error by a factor of fifty. The remaining factor of six comes
because the force of gravity in the black hole plus rock sphere system
increases rather than decreases as you approach the centre.)
>
>Compressional energies of the black hole, if given enough time would be much
>larger of course.
You completely missed the reason I chose 1000km. That's directly
related to how much time there is. It's a mere stab at an appropriate
value, but not an arbitrary figure.
> (A detailed analysis
>> would involve estimating a pressure-density curve for core material -
>> I've done it the lazy way by assuming that gravitational acceleration to
>> a specified radius can be used instead of the pressure.
>
>And you did it wrong of course.
No, I did it right except for a factor of three, which doesn't matter
much in this context. Turns out it was easy to solve properly anyway.
Perhaps you'd like to try, as a much needed exercise.
>> For reasons I
>> won't go into, and which you wouldn't understand anyway, these figures
>> will be an overestimate.)
The rock really isn't going to compress so much, so fast.
>More than likely you guesstemated order of magnitude, hooked your finger and
>fished some numbers out of your ass. You are right, I don't understand why
>you would fish numbers out your ass since a first approximation answer is
>trivial to compute.
A pity you cannot perform even trivial computations, then.
>>
>> As the black hole passes, much of this energy will be recovered as the
>> core material expands like an ideal gas. The remainder will appear as
>> heat, and will also cause slowing of the black hole.
>
>*sigh*
>
>If core material expands like an ideal gas, it would be symmetric in all
>directions. This would not slow the free space black hole unless the
>ejected material were a jet in the direction of travel. This is basic
>physics 101 here.
Blunder number two, or - more accurate - the first of an entangled ball
of blunders. You really don't understand the physics at all, do you?
The *pressure*, not the expansion, of an ideal gas is isotropic. Its
expansion depends on the confining pressure. Here, in fact, the rock
will expand back pretty much in the direction it came from. The slowing
of the black hole is related to the expansion, but it is nothing to do
with any jets. I know you would not understand this concept. Repeat
after me "INELASTIC GRAVITATIONAL INTERACTION".
>Fluctuatutions in density and distribution would lead to a non symmentrical
>expuslion of matter that will change the velocity of the black hole
>randomly.
You utter plonker. The rock will expand adiabatically and cool after
the black hole passes, but it will not symmetrically return to its
former state. Instead, it will expand more slowly than it contracted.
The black hole will experience an increased gravitational attraction
from behind, and will be slowed. The magic of energy conservation will
ensure that the heat and other random kinetic energy finally dumped into
the Earth will exactly equal the kinetic energy lost by the black hole.
(And please don't protest that energy conservation doesn't apply in
general relativity. This is the Newtonian regime, and it applies here.)
You clearly don't get this at all, so you came up with naive nonsense
about the black hole being randomly buffetted by jets of material.
>
>If it is passing though the Earth, the black hole would be significantly
>slowed down if its accretion surface was 500km in radius. Processes would
>include bond breaking energy of the "rock" in the crust, mantel and core.
>Degeneracy of the compressed material. Friction. Etc. In fact, there is a
>good chance that the black hole would be captured inside the crust, or at
>least captured in a harmonic motion where it passed multiple times before
>being caught in the crust. This would be devastating to the planet for
>obvious reasons.
If it's accretion surface were 500km in radius, it sure would be one
heck of a black hole, and my calculations would be incorrect. But where
on earth do you get such a figure? The black hole is minuscule, and
matter will only move relativistically towards it at a very small
distance. You'd need relativistic motion to get any sort of decent
accretion surface on the scales we are talking about. This black hole
will be a very hot, very small object - I'd guess about a metre in
diameter (i.e. infalling material is starting to 'choke' at this
distance).
>
>> However, the
>> energy will only be a fraction of the black hole's kinetic energy (2 x
>> 10^31 J) and will not prevent it escaping the Earth.
>KE = 1/2 M v^2
>M= Mbh + Mrock = 6E24kg + 12E21kg =6.012E24 kg = 6E24 kg
>v=20km/s
>KE = 1.2E33 J
>Again, check your numbers.
>
>> By contrast, the comet's kinetic energy (the same amount, 2x10^31 J)
>
>Where did you get this number?
>
I see you had to check yours, and reduce them by a factor of ten. But
yes, I was out by a factor of five. I had 2x10^32 and then carelessly
divided by ten again, which I had already done. The correct value, for
black hole or comet, is 1.2x10^32 J.
>> will be entirely converted into heat energy. Thus the comet will be
>> more than 100 times as devastating as the black hole. An moreaccurate
>> figure would probably be 1000 or perhaps even 10000 times.
>
>Faulty logic, faulty physics.
>The "expanding gas" of the accretion shell of "rock" has to dump its energy
>somewhere. The energy would be dumped into the crust, mantel and core of the
>planet as it passed through. Check above.
Nope, your knowledge of ideal gases clearly does not extend to the
notion of cooling on expansion. Lots of the energy will be expended in
this way, and will not go towards destroying the Earth. Furthermore,
the total energy, calculated above as 1.4x10^30 J, is only about a
hundredth of the kinetic energy of the black hole. So the comet will do
a hundred times more damage, multiplied by a factor corresponding to
whatever elasticity the material of the Earth can muster - probably
quite high.
>The best you could hope for would be the same amount of damage.
No, the worst you could expect would be several hundred times less.
Plonker.
>
>>- I challenge you to do better,
>
>I did, I could and at least I got the math correct.
ROFL.
[--]
>> What do *you* think will happen when a
>> black hole, one-tenth the mass of the earth, and travelling at 20km/s,
>> hits us.
>
>As stated above:
>
>However, even before the black hole struck there would be a massive tidal
>force given by:
>The time it would take at 20km/s to reach the Earth would be a little less
>than 17 hours. During this time the Earth would feel a tidal force at least
>as great as that of the Moon and getting larger as the inverse cube of the
>distance.
>This would wreak havoc on the Earth in its own right.
>Just another small effect you neglected.
Pretty insignificant compared to the release of up to 10^30J when it
hits, I should think. But yes, I didn't consider it.
[--]
>>
>> Material flowing relativistically towards the event horizon will only
>> amount to the equivalent of a 30m sphere of matter during the time
>> available for accretion.
>
>Again, did you pull this number out of your ass? I would bet that you did.
What's so difficult about multiplying area x velocity x time?
>
>> Since the temperature will counteract the
>> pressure effects, this is a generous (over)estimate of the maximum
>> amount of rock or other matter that can be absorbed by the black hole.
>
>Perhaps.
>
>> It is insignificant. Therefore flying cows will only reach the
>> accretion zone.
>
>Ever?
Ever. A few molecules of cow may make it. Cows won't.
[--]
>> Put up or shut up, you arrogant, smirking, ignorant loon.
>
>Arrogant and smirking loon, yes. Ignorant, in some matters yes.
>However, while I might be ignorant, you are just plain stupid. Ignorance
>can be cured, stupidity cannot.
>
Perhaps you will reflect on the above while pondering your inept
attempts at analysis.
- Gerry Quinn
Gerry Quinn
>"Martin Brown" <martin...@pandora.be> wrote in message
>>
>> I don't think so, but I am open to being convinced otherwise by a reasoned
>> argument.
>
>Lets see.
>A comet 0.1 Earths mass hits the Earth. Boom! Kinetic energy.
>A BH 0.1 Earth's mass hits the Earth, accretes a 500km, radius shell of
>rock, compacted from 1000 km shell (Quinn's numbers for whatever reason, not
>mine) and hardly slowing down (your contention). Boom! Nearly the same KE.
Mechanics 101, Varney. The energy release is dependent on the degree of
slowing down.
The 1000km is nothing to do with accretion per se. It is the region in
which significant gravitational work is done on the core material. This
work provides an upper limit for the energy release.
- Gerry Quinn
Gerry Quinn
>>
>>Faulty logic, faulty physics.
>>The "expanding gas" of the accretion shell of "rock" has to dump its energy
>>somewhere. The energy would be dumped into the crust, mantel and core of the
>>planet as it passed through. Check above.
>
>Nope, your knowledge of ideal gases clearly does not extend to the
>notion of cooling on expansion.
Of course there is also work done against gravity during the expansion,
this also causes cooling. And we could talk of the pressure of
overlying rock, or lump it in with the gravitational work.
- Gerry Quinn
Gerry Quinn
>
>You utter plonker. The rock will expand adiabatically and cool after
>the black hole passes, but it will not symmetrically return to its
>former state. Instead, it will expand more slowly than it contracted.
>The black hole will experience an increased gravitational attraction
>from behind, and will be slowed. The magic of energy conservation will
>ensure that the heat and other random kinetic energy finally dumped into
>the Earth will exactly equal the kinetic energy lost by the black hole.
Actually, a bit goes into the Earth's kinetic energy too.
- Gerry Quinn
Michael Varney
> In article <JeBe7.1927$kH1.4...@news.uswest.net>, "Michael Varney"
<mva...@muswest.net> wrote:
> >Here is my analysis of the comments of Quinn. He was crying and whining
so
> >much that I just broke down and decided to give his comments a fair
reading.
> >"Gerry Quinn" <ger...@indigo.ie> wrote in message
>
> Varney's attempts at physics are as laughable as I predicted. I shall
> deal with his more egregious blunders one by one.
> >> >
> >> >"More of a black holes mass is near its surface" is valid?
> >> >*smirk*
> >>
> >> In the metric of the classical analysis that is appropriate to this
> >> problem, yes, all its mass is much less than 6000km from an
> >> appropriately defined surface.
> >
> >Why did you state 6000km the event horizon of a .1 Earth mass black hole?
>
> Er, Michael, 6000km is the radius of the Earth.
We were talking about black holes. Your reading comprehension needs work.
> >Remember, this is what you stated:
> >"More of a black holes mass is near its surface"
>
> IH@ateSpam stated this, making a comparison between a black hole and the
> earth.
> >This would imply, and is something you stated later as obvious, that
"its"
> >surface was in fact the event horizon.
>
> Actually, an appropriate 'surface' would, as I stated, be the edge of
> the accretion zone, where infalling matter is diverted to a considerable
> extent from its inward fall. But either way, by any reasonable
> definition of 'surface', it is small compared to the Earth's.
>
> >Please note that a singularity, where ALL the mass (that is not in free
fall
> >between the event horizon and the singularity) of a black hole resides
> >according to current models, in a region a size at most the Planck
length.
>
> I think
No, you don't.
> you mean last century's models. Even in general relativity you
> are blundering, though, because according to the instruments of any
> hypothetical observers, the mass is 'frozen' and has not reached any
> putative central singularity. [The central singularity concept is a bit
> of a joke anyway, IMO, but that is irrelevant to the current debate.]
You are showing your total ignorance about black hole physics.
http://origins.colorado.edu/~ajsh/home.html
> >When dealing with a black hole, the metric for a spherically symmetric,
> >non-spinning uncharged body of large mass is the Schwarzschild metric,
not a
> >"metric of classical analysis".
>
> But we are dealing with a black hole and a planet, and I am using the
> metric of the planet. Which to all intents and purposes is flat.
> Indeed, I analyse the black hole as a compact classical object, so talk
> of metrics doesn't really come into it.
*sigh* twit.
<SNIP>
> >> But in any case, the situation, in
> >> broad outline, is not difficult to analyse. We analyse the black hole
> >> as a compact classical object, with a surface whose size is on the
order
> >> of metres or a bit larger.
> >
> >This would not be a correct assumption, especially for a .1 Earth mass
black
> >hole.
> >The radius of a black hole can be calculated by by Newtonian physics, and
> >leads to the correct equation for the radius of a black hole.
> >In any event, the result for a Schwarzschild black hole's event horizon
is:
> >r = 2M where r is the reduced circumference.
> >And for a 0.1 Earth Mass black hole:
> >r = 8.88mm
>
> As I state below, the appropriate definition of 'surface' is nothing to
> do with the event horizon. Just like the Earth's surface, it's the
> region in which objects falling in are diverted from their path. This
> will probably be at a radius of metres. (It certainly won't be anything
> like the nonsensical 500km you come up with later...)
You came up with the 500km, not I.
> >
> >I point out to you that in another post you stated that:
> >"In the metric appropriate to the Newtonian approximation, the black hole
> >will have a Schwarzschild radius of less than a millimetre."
> >Which is wrong, of course.
>
> Yes, I accidentally dropped a factor of ten.
I guess you do pull numbers out of your ass without calculating.
QED.
<SNIP>
*sigh* Twit.
The graviational work done by compressing the mass of rock is the same
regardless of what is at the center. But of course you would not understand
this.
> I did a proper calculation
No, most likely you pulled some more numbers and physics out of your ass.
<SNIP>
> >Compressional energies of the black hole, if given enough time would be
much
> >larger of course.
>
>I chose 1000km.
Yes, _you_ did.
> > (A detailed analysis
> >> would involve estimating a pressure-density curve for core material -
> >> I've done it the lazy way by assuming that gravitational acceleration
to
> >> a specified radius can be used instead of the pressure.
> >
> >And you did it wrong of course.
>
> No, I did it right except for a factor of three
Oh, I guess wrong is not the politically correct term then? Oh, how about
"not optimally correct?"
<SNIP the rest>
It is obvious that you are simply an argumentative dolt. That is ok. At
least you cannot do much harm behind a sales counter.
*PLONK*
Gerry Quinn
>"Gerry Quinn" <ger...@indigo.ie> wrote in message
>> do with the event horizon. Just like the Earth's surface, it's the
>> region in which objects falling in are diverted from their path. This
>> will probably be at a radius of metres. (It certainly won't be anything
>> like the nonsensical 500km you come up with later...)
>
>You came up with the 500km, not I.
In an entirely different context. It was merely an aid to guesstimating
the interaction energy, and does not correspond to any physical surface.
You, however, imagined that it was a plausible size for the accretion
zone, whereas it is of course grotesquely large - a metre or so is
plausible.
>>
>> This is the first of two blunders, either of which, taken on its own,
>> would prove your incompetence to match your arrogance. Have you
>> forgotten that there is a ***black hole*** at the centre of this ball of
>> rock? (Of course it's really a tube, I used a 1000km ball because it's
>> easy to calculate that 1000km or so is the distance at which a
>> free-falling object could fall all the way in to the black hole in the
>> time available. So it's a convenient guesstimate of the amount of rock
>> that's going to be compressed.)
>
>*sigh* Twit.
>
>The graviational work done by compressing the mass of rock is the same
>regardless of what is at the center. But of course you would not understand
>this.
Are you really that dumb, Varney? Work is force x distance. Guess what
happens to the force when a black hole is in the middle of the sphere?
I will note that we are not really talking about the details of rock
compression here, but the amount of gravitational energy that is
available. That's why the difficult stuff about equations of state etc.
can be bypassed. I'm actually treating the rock pretty much as a gas.
>
>It is obvious that you are simply an argumentative dolt. That is ok. At
>least you cannot do much harm behind a sales counter.
>
>*PLONK*
The authentic sound of a plonker.
If you're really kill-filing me (or pretending to) it is clear in your
case that you are admitting defeat. Because your normal mode of
behaviour with those whose you consider cranks (sometimes correctly, it
must be admitted) is to harass them with endless meaningless one-line
posts in response to everything they say. You can't attack my posts
because your ability is insufficient, and you can't read them and learn,
for that would cause too much pain to your brittle ego. Still, it seems
I am rid of you, as I hoped.
God help your students.
- Gerry Quinn
Martin Brown
Michael Varney wrote:
> "Martin Brown" <martin...@pandora.be> wrote in message
> news:3B7B7DCF...@pandora.be...
> >
> > Michael Varney wrote:
> >
> > > "Gerry Quinn" <ger...@indigo.ie> wrote in message
> > > news:Np9e7.1517$s5.2...@news.indigo.ie...
> > > > In article <9l9fe2$em7$1...@peabody.colorado.edu>, "Michael Varney"
> > > <var...@coloradospam.edu> wrote:
> > > > >"Gerry Quinn" <ger...@indigo.ie> wrote in message
> >
> > > In any event, the result for a Schwarzschild black hole's event horizon
> is:
> > >
> > > r = 2M where r is the reduced circumference.
> > >
> > > For the mass of the Earth:
> > > M = 4.44E-3 meters
> > > Therefore r = 8.88 cm
> > >
> > > And for a 0.1 Earth Mass black hole:
> > > r = 8.88mm
> > >
> > > I point out to you that in another post you stated that:
> > >
> > > "In the metric appropriate to the Newtonian approximation, the black hole
> > > will have a Schwarzschild radius of less than a millimetre."
> > >
> > > Which is wrong, of course.
> >
> > No. It is you who are wrong. And you are very graceless about it too.
> > Every one else on the planet can see that 2 x 4.44E-3 m = 8.88mm
>
> Yes, the point was to see if Quinn actually checked his numbers, and that of
> others. I tried to be obvious about it, but perhaps too obvious? I guess
> Quinn is saved from having to think a little.
> Oh well.
I'm sorry but I simply don't believe you. You even posted a "correction" to that
post. I am forced to assume that you do not know the difference or understand
your errors. You have made enough blunders in other posts to convince me that
you do not know what you are talking about.
> > I'd be content with numbers estimated to the nearest power of ten anyway.
> > There are far too many gross approximations needed for the interaction of
> > rock/iron core with a BH to worry about small leading constants of O(1).
>
> Not counting, if we consider a Kerr metric, interactive effects with the
> magnetic field of the planet, frame dragging, etc.
They are still second order effects compared with the two main energy terms. The
projectiles classical kinetic energy, and the gravitational potential energy
released by material dropping into the black hole. The former dominates in all
scenarios I can foresee.
> > Others have dealt with more complex cases. The difficulty here is that AFAIK
>
> > noone has bothered to work through the effects of a BH moving through a
> planet.
>
> There is a guy I know who Gregory Benford contacted with this sort of
> problem for his book "The Eater", or was it "Artifact" that did some back of
> the envelope calculations. I wonder what he would say about this.
I would be happy to see his calculations. I posted the original question in the
hope that a few people who knew about the latest details of the accretion
process might comment on how things would actually behave in the case of a
planetary rock/iron core interacting with a BH.
> > It isn't a particularly likely scenario except in Hollywood movies and BBC
> > "science" programmes.
>
> Or in science fiction novels. Or in the planets where it has undoubtedly
> already happened.
Science fiction doesn't bother too much about scientific accuracy. Neither do
you.
> > > > As the black hole passes, much of this energy will be recovered as the
> > > > core material expands like an ideal gas. The remainder will appear as
> > > > heat, and will also cause slowing of the black hole.
> > >
> > > *sigh*
> > >
> > > If core material expands like an ideal gas, it would be symmetric in all
> > > directions. This would not slow the free space black hole unless the
> > > ejected material were a jet in the direction of travel. This is basic
> > > physics 101 here.
> >
> > Compressing and heating the material in front of it must come at the
> expense of
> > a slight loss of KE (and momentum). However, it seems that for modest
> sizes of
> > BH there is little chance of the amount a matter accreted going through a
> planet
> > halting it or even slowing it significantly.
>
> Please note the words "free space". And note the paragraphs that you
> snipped, which I assume you agree with.
Do not dare to assume that I agree with anything else you have said. There is a
limit to how much of your posting I can be bothered commenting on and
correcting. You are an unreliable poster whose postings are full of errors which
you claim are deliberate. You seem not to understand basic physics even if you
do know some of the buzz words from a GR course.
> > > If it is passing though the Earth, the black hole would be significantly
> > > slowed down if its accretion surface was 500km in radius. Processes would
>
> > > include bond breaking energy of the "rock" in the crust, mantel and core.
> > > Degeneracy of the compressed material. Friction. Etc. In fact, there is a
> > > good chance that the black hole would be captured inside the crust, or at
> > > least captured in a harmonic motion where it passed multiple times before
> > > being caught in the crust. This would be devastating to the planet for
> > > obvious reasons.
> >
> > This doesn't sound right. Lets see your numbers.
>
> How about seeing your numbers? You have yet to offer any (beyond the
> obvious). How about some of the physics?
If you were not so wrapped up in your private war with other posters on s.p.r
you would have noticed that when I posed the question I provided a series of
ballpark scenarios with energetics for objects ranging from a big asteroid to
3Msun to start the ball rolling.
Lets see if you can find an error in one of my postings? There are some.
I have even pointed out areas where I know the approximations made are gross but
vaguely justifiable for back of the envelope calculations.
You have repeatedly asserted the Schwarzchild radius of an Earth mass black hole
is the wrong size, and made a host of other conceptual errors about the
approximate physics of the situation.
> You were hoping to read about effects of a black hole going through a planet
> but were bummed that we did not enlighten you. How about you doing the
> analysis and enlightening us?
I did. I posted it in the original question. If you wish to post like a spoilt
brat then fine, but you do not post reliable information even at the level of
basic undergraduate classical physics.
I pity anyone you are supposed to be teaching this stuff to.
> > That's the original paper of SP&B I referred to above. If anything their
> results
> > imply that accretion into the black hole will be largely choked off during
> its
> > passage through the Earth.
> > Black holes it seems choke on excessively rich food.
>
> So it would seem.
If you wish to post accurately about the physics of the problem in hand then
please do so.
Regards,
Martin Brown
Gerry Quinn
>I would be happy to see his calculations. I posted the original question in the
>hope that a few people who knew about the latest details of the accretion
>process might comment on how things would actually behave in the case of a
>planetary rock/iron core interacting with a BH.
>
I may try having a more detailed crack at it over the next few days.
It's an interesting problem, yet it doesn't seem really hard
in principle.
- Gerry Quinn
Lucius Chiaraviglio
>Would the solar system really be laid waste by a visiting
>black hole the size of a pea?
>I am not convinced. What do others think ?
A major part of the answer depends upon whether the black hole manages
to get stuck in something, and just what it gets stuck in. Anything that it
gets stuck in (which could happen if it fell in at only slightly over escape
velocity, and then experienced braking due to gravitational interaction with
nearby matter) will eventually be destroyed -- partly converted into more
black hole mass, and partly ejected violently by the energy radiated by (or
otherwise transferred from) infalling matter. The latter process will ensure
a messy end for the devoured object and for anything nearby, so a black hole
falling into the Sun will eventually ensure that the planets get toasted --
the explosion would probably appear as a small supernova to distant observers
(but slower due to the lower density of infalling matter resulting in a more
leisurly rate of accretion even in the final stages, compared to the collapse
of a highly evolved stellar core).
We should be able to place an upper limit on the frequency of
occurrence of micro-sized black holes by looking for star-destroying
explosions that are larger than a normal nova but smaller than a normal Type
II supernova. Later, with better capabilities for detecting gravitationally
lensing objects, we should be able to make a similar estimate by looking for
low-end stellar mass black holes (of mass lesser than the neutron star
maximum). Of course, this upper limit will not be very stringent in areas of
low star density, because collisions between stars and things of similar
frequency of occurrence (including other stars) are rare in general. To get
a good upper limit, it would be necessary to look in globular clusters, where
the occurrence of blue straggler stars proves that stellar collisions occur
at a noticeable rate, and thus other objects would also have a fair chance of
falling into a star. (Blue stragglers are stars that are too massive to have
stayed on the main sequence since the formation of the globular cluster, which
has had basically no star formation much beyond the formation of the cluster.
They occur too frequently and have the wrong elemental abundances for all of
them to be captured field stars, so at least some of them must be the results
of smaller stars in the cluster colliding and merging.)
--
Lucius Chiaraviglio
E-mail address is approximately: lucius1@telo_large_urban_area.com
To get the exact address: ^^^^^^^^^^^^^^^^^
Replace indicated characters with common 4-letter word meaning the same thing
and remove underscores (Spambots of Doom, take that!).
Russell Lawson
in time for Christmas, as this would make a truly unique viewing
experience; a docu-drama!
I think Mr Varney is by far and away the *star* of the show and should
be signed up to commision further docu-dramas such as:
"what do you get if you ask a question about a very complicated and
in-depth subject, with a view to an exchange of opinion and ideas, for
which someone tries an honest response and in doing so offers some of
their opinions, while a third person decides to try and cut them apart
with boring childish self-important sarcasm?"
Very entertaining guys, funniest thing i've seen in ages.
R
"Michael Varney" <mva...@muswest.net> wrote in message news:<7AVe7.787$kR1.4...@news.uswest.net>...
> "Gerry Quinn" <ger...@indigo.ie> wrote in message
> news:eFSe7.2185$s5.3...@news.indigo.ie...
> > In article <JeBe7.1927$kH1.4...@news.uswest.net>, "Michael Varney"
> <mva...@muswest.net> wrote:
> > >Here is my analysis of the comments of Quinn. He was crying and whining
> so
> > >much that I just broke down and decided to give his comments a fair
> reading.
*snip*
Lucius Chiaraviglio
>In article <8r9dnt85mt7sh0l2v...@4ax.com>, I...@te.spam wrote:
>>On Sun, 12 Aug 2001 09:14:02 GMT, ger...@indigo.ie (Gerry Quinn)
>>wrote:
>>>Comets couple electromagnetically to the earth - black holes only
>>>gravitationally.
>>Say what? since when are comets anything more than electrically
>>neutral in the most part?
>
>You're right, I guess, it's the size and the propensity for breaking up
>that really count.
I think a misunderstanding is going on here. Comets do indeed
interact electromagnetically to the Earth, but the overwhelming majority
of this is only on the atomic scale, at which point the electromagnetic
interaction shows itself as the resistance of atoms to compression below
their normal atomic radii. This makes for rather efficient conversion of
bulk kinetic energy into heat energy.
Gerry Quinn
>ger...@indigo.ie (Gerry Quinn) wrote:
>>In article <8r9dnt85mt7sh0l2v...@4ax.com>, I...@te.spam wrote:
>>>On Sun, 12 Aug 2001 09:14:02 GMT, ger...@indigo.ie (Gerry Quinn)
>>>wrote:
>>>>Comets couple electromagnetically to the earth - black holes only
>>>>gravitationally.
>>>Say what? since when are comets anything more than electrically
>>>neutral in the most part?
>>
>>You're right, I guess, it's the size and the propensity for breaking up
>>that really count.
>
> I think a misunderstanding is going on here. Comets do indeed
>interact electromagnetically to the Earth, but the overwhelming majority
>of this is only on the atomic scale, at which point the electromagnetic
>interaction shows itself as the resistance of atoms to compression below
>their normal atomic radii. This makes for rather efficient conversion of
>bulk kinetic energy into heat energy.
>
Yes, and the size of the comet, compared to the size of a black hole of
similar mass, means that it gets to interact a lot more efficiently,
i.e. it interacts more strongly with more of the planet. 2000 km from
the black hole, the only forces exerted by it are equal to earth's
gravity. 2000 km from the centre of the comet, it's atoms are smashing
into those of the Earth as you describe.
- Gerry Quinn