A small doubt about "clock paradox".
V.Gopal
"moving clocks run slow". What is not clear is that, when a 'clock
runs slow' whether its frequency continuously decreases or not. Can
anyone clarify this point?
m4r...@xs4a11.nl
> In Special Relativity Theory the basis of "Twin Paradox" is that
> "moving clocks run slow". What is not clear is that, when a 'clock
> runs slow' whether its frequency continuously decreases or not.
On the contrary, that is perfectly clear. The "speed" of the clock
is directly related to its velocity. If the velocity is constant
then so is the clockrate.
Uncle Al
Nothing runs "slow" in any refernce frame. When otherwise identical
clocks - one of which sustained a velocity relative to the other - are
brought together to compare, one is seen to have less elapsed time
than its twin due to its hyperbolic rotation through 4-space. The
skewing factor is sqrt[1-(v^2/c^2)].
No clock need be accelerated for the Twin Paradox to occur.
Given any achievable velocities V1 and V2 and any finite lightspeed,
the sum of the velocities as viewed by any inertial observer cannot
exceed
(V1 + V2)/[1 + (V1)(V2)/c^2]
This is transformation of velocities parallel to the direction of
motion. For velocities at an arbitrary angle theta,
u_parallel = (u'_parallel + v)/(1+(v dot u')/c^2)
u_perp = u'_perp/(gamma_v(1+(v dot u')/c^2))
Makes no difference who does the looking. Any inertial observer has a
valid reference frame. Disparities are only noted upon comparison of
reference frames. Spacetime is four-dimensional; travel through
spacetime is a hyperbolic rotation of all four coordinates. However,
the units of time are seconds not meters. ct is a nice length, but
the this fundamental unit of length is a very long one.
At nominal velocities you don't travel much along ct compared to
x,y,x. Galilean transforms and Newtonian physics are good enough
approximations. At relativistic speeds you propagate along ct
comparable to a material dimension. You need Lorentzian transforms
and relativity to explain initially synchronized clocks separated and
then brought together for comparison thereafter.
Acceleration of one observer has nothing to do with it, BTW.
1) Acceleration is an absolute measurement. There is no doubt who
is accelerated.
2) Acceleration is irrelevant.
We have three identical clocks that are off (a state of not running)
and zeroed. Each clock has a very short toggle jiggger switch
sticking out. We load them in individual spaceships and set up the
experiment.
CLOCK 1: That's our clock. It sits stationary in our inertial
reference frame with a little jigger sticking out. Touch the jigger
and the "off" state becomes "on" or the "on" state becomes "off."
Clock 1 is "off."
CLOCK 2: In a spaceship traveling at 0.999c relative to our
inertial frame of reference. Clock 2 is "off." It skims past Clock
1, the jiggers touch, both Clocks 1 and 2 are now "on" and
synchronized.
CLOCK 3: In a spaceship traveling at 0.999c relative to our
inertial frame of reference, but 180 degrees counter in direction to
Clock 2. Clock 3 is "off." Some arbitrary time after Clocks 1 and 2
synchronize and turn "on" by touching, Clocks 2 and 3 brush past each
other, touching jiggers. Clock 2 is now "off," Clock 3 is now "on."
CLOCK 1: That's our clock. It sits stationary in our inertial
reference frame with a little jigger sticking out. Clock 3 rushes
past, jiggers touch. Clocks 3 and 1 are now off. All clocks are
off. No clock has accelerated while "on."
BOTTOM LINE: Get all three clocks together and compare elapsed
times. Elapsed time #2=#3, but elapsed time #2+#3 does not equal #1,
the local stationary reference frame summation. The sum of #2+#3
elasped time is only about 4.5% that than of #1's accumulated elapsed
time. You now have the Twin Paradox without any running clock having
been accelerated.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!
larry
An infinitesimal length, if there is to be no acceleration of any part
of the clocks, unless acceleration of parts of the clocks does not
matter. Since, to move a jigger, one must accelerate it and possibly
the whole clock, does that not count as an acceleration of a clock?
Larry
Uncle Al
You are so are so ignorantly hopelessly fill of shit. You have no
idea what is going on. Replace the jiggers with complimentary
fiberoptic emitters and pinhole photodiode detectors. Have the ships
skim within 1 millimeter of each other to transfer synchronization.
Run your spew to bull bore. Show how:
"Elapsed time #2=#3, but elapsed time #2+#3 does not equal #1, the
local stationary reference frame summation. The sum of #2+#3 elasped
time is only about 4.5% that than of #1's accumulated elapsed time"
does not obtain. Now assume the experiment is 3 years elapsed time in
the stationary frame and show it again. Show us how three teeny dinks
make up for over 1045 days missing between the sum of the moving
clocks' elapsed time and the stationary clock's elasped time. Now do
it for 10 years, 100 years. How good is your spew now?
George Greene
: Nothing runs "slow" in any reference frame.
This begs the question of how you are supposed to
be able to measure what a clock says "now" when it
is somewhere else.
: When otherwise identical
: clocks - one of which sustained a velocity relative to the other - are
: brought together to compare, one is seen to have less elapsed time
: than its twin due to its hyperbolic rotation through 4-space. The
: skewing factor is sqrt[1-(v^2/c^2)].
You can't assert this symmetrically.
It cannot be the case BOTH that clock a has less time elapsed
than clock b AND that clock b has less time elapsed than clock a.
: No clock need be accelerated for the Twin Paradox to occur.
Please. The clocks have to be acclerated just to get back
to the same place, in order for the comparison to occur.
: Makes no difference who does the looking. Any inertial observer has a
: valid reference frame. Disparities are only noted upon comparison of
: reference frames.
What does it even mean to compare two whole frames, as opposed
to just two clocks?
: Acceleration of one observer has nothing to do with it, BTW.
:
: 1) Acceleration is an absolute measurement. There is no doubt who
: is accelerated.
: 2) Acceleration is irrelevant.
It's not irrelevant to your thought-experiment below.
: We have three identical clocks that are off (a state of not running)
: and zeroed. Each clock has a very short toggle jiggger switch
: sticking out. We load them in individual spaceships and set up the
: experiment.
:
: CLOCK 1: That's our clock. It sits stationary in our inertial
: reference frame with a little jigger sticking out. Touch the jigger
: and the "off" state becomes "on" or the "on" state becomes "off."
: Clock 1 is "off."
:
: CLOCK 2: In a spaceship traveling at 0.999c relative to our
: inertial frame of reference. Clock 2 is "off." It skims past Clock
: 1, the jiggers touch, both Clocks 1 and 2 are now "on" and
: synchronized.
:
: CLOCK 3: In a spaceship traveling at 0.999c relative to our
: inertial frame of reference, but 180 degrees counter in direction to
: Clock 2. Clock 3 is "off."
No acceleration so far.
: Some arbitrary time after Clocks 1 and 2 synchronize and turn
: "on" by touching, Clocks 2 and 3 brush past each other,
: touching jiggers. Clock 2 is now "off," Clock 3 is now "on."
: CLOCK 1: That's our clock. It sits stationary in our inertial
: reference frame with a little jigger sticking out. Clock 3 rushes
: past, jiggers touch. Clocks 3 and 1 are now off. All clocks are
: off. No clock has accelerated while "on."
NOR while off, EITHER, yet, in this scenario.
: BOTTOM LINE: Get all three clocks together
But THAT will REQUIRE acceleration. If their velocities
don't change then the clocks will NEVER "get together".
: and compare elapsed times. Elapsed time #2=#3, but elapsed time
: #2+#3 does not equal #1, the local stationary reference frame
: summation. The sum of #2+#3 elasped time is only about 4.5%
: that than of #1's accumulated elapsed time. You now have the
: Twin Paradox without any running clock having been accelerated.
But you also have the presumption that you know what a clock
reads EVEN though it is not HERE for you to be able to actually
OBSERVE, now. Getting it here would require acceleration, EVEN
if it is off. Somehow I think the fact that acceleration must
still occur must still be relevant, EVEN if the clock is off.
--
---
"It's difficult ... you need to be united to have any
strength, but internal issues have to be addressed."
--- E. Ray Lewis, on liberalism in America
Richard
When you can define time, then maybe your input will be interesting.
Clocks do not measure the passage of time, they 'register' an internal
velocity (of some mass or system of mass) times it's displacement,
either linear or angular depending upon the type of clock, an internal
velocity that must change in order for the registered 'ticks' to get out
of sync with another clock. A change in velocity does not a change in
time equal. Now suppose I adopt the motion of an elastic ball between to
walls as my time-piece:
1) How will this clock differ fundamentally from any other clock?
2) Since when will an acceleration of the elastic ball constitute a
change in the rate that I am passing through time, rather than
constituting simply an increase in its intrinsic frequency wrt time?
Richard
Uncle Al
>
> Uncle Al wrote:
> >
> > "V.Gopal" wrote:
> When you can define time, then maybe your input will be interesting.
> Clocks do not measure the passage of time, they 'register' an internal
> velocity (of some mass or system of mass) times it's displacement,
> either linear or angular depending upon the type of clock, an internal
> velocity that must change in order for the registered 'ticks' to get out
> of sync with another clock.
Radioactivity, shithead. You look at the declining rate of decay and
that is your clock. Why don't you tell us where the "internal
velocity" is in radioactivity?
[snip of more uninspired idiocy]
V.Gopal
All calculations in Special Theory of Relativity are based on the law
of conservation of momentum and kinetic energy. Acceleration is
questionable in Special Relativity Theory because force and
accelerational, in general, are not codirectional in special
relativity. Moreover, in general action and reaction are not equal and
opposite. The distinction between force and power as well as the
distinction between momentum and kinetic energy are blurred. Special
relativity begins by assuming conventional mechanics as its premise
(the starting point) and contradicts its own premise. How can a
conclusion contradict its own premise?
A clock cannot be said to run slow unless it has angular deceleration.
Therefore everybody seems to agree that clocks 'become' slow - they
decelerate during linear acceleration of the point mass. It is obvious
that if speed of light is the maximum speed attainable then linear
acceleration must become zero when speed of light is reached. If we
want to make linear acceleration of the mass zero then in,
acceleration=(V2-V1)/T, the clock that shows T in the denominator must
stop or take infitite time to sweep through an arc equal to the arc
that shows one unit of time in a clock at rest.
The real problem is how to make the value of linear acceleration zero
when a mass attains the speed of light. Neither Newton nor Einstein
nor any of us can find the right answer to this problem.
Doug Magnoli
In order for the jiggers of the clocks of spaceships 1 and 2 to click
each other on, the two spaceships have to have a certain orientation
relative to each other. We'll say that spaceship 2 zooms by on the right
of spaceship 1, so spaceship 2's clock jigger is sticking out on the
left.
Now in order for the jigger of the clock of spaceship 3 to click off the
jigger of spaceship 2, spaceship 3 has to occupy the same position
relative to spaceship 2 that spaceship 1 did. In order to hit the clock
jigger of spaceship 2, which sticks out on the left, spaceship 3 has to
pass spaceship 2 on the left of spaceship 2.
Now in order to follow the same trajectory that spaceship 2 followed,
only backwards and translated by one spaceship-width, spaceship 3 will
ram into spaceship 1 at 0.999 c, a collision from which we expect to be
unable to recover any clock fragments, leaving only one clock with
nothing to compare it to.
-Doug Magnoli
[Delete the two and the three for email.]
Ronald Stepp
news:3DB8B27D...@attbi.com...
> Now in order to follow the same trajectory that spaceship 2 followed,
> only backwards and translated by one spaceship-width, spaceship 3 will
> ram into spaceship 1 at 0.999 c, a collision from which we expect to be
> unable to recover any clock fragments, leaving only one clock with
> nothing to compare it to.
It's a thought experiment to illustrate how it works.. I hope you're joking
when you use this to disprove the experiment.
Franz Heymann
"Richard" <no_mail...@yahoo.com> wrote in message
news:3DB8849F...@yahoo.com...
Fast mesons live longer than stationary muons. What goes tick tock in a
meson?
Franz Heymann
Edward Green
> "V.Gopal" wrote:
> >
> > In Special Relativity Theory the basis of "Twin Paradox" is that
> > "moving clocks run slow". What is not clear is that, when a 'clock
> > runs slow' whether its frequency continuously decreases or not. Can
> > anyone clarify this point?
That would be a second order "running slow", wouldn't it -- an
acceleration of slowness.
> Nothing runs "slow" in any refernce frame. When otherwise identical
> clocks - one of which sustained a velocity relative to the other - are
> brought together to compare, one is seen to have less elapsed time
> than its twin due to its hyperbolic rotation through 4-space. The
> skewing factor is sqrt[1-(v^2/c^2)].
> No clock need be accelerated for the Twin Paradox to occur.
I doubt this. I've seen you make this claim before. Let's take a
closer look ...
>
> Given any achievable velocities V1 and V2 and any finite lightspeed,
> the sum of the velocities as viewed by any inertial observer cannot
> exceed
>
> (V1 + V2)/[1 + (V1)(V2)/c^2]
What? Given any "achievable velocities" v1 and v2, the sum is bounded
by 2c. Since the frame in which the sum is 2c - eps is an inertial
frame, that is your bound: v1 + v2 < 2c.
Alright Al -- I think you've become a relativity crank in your old
age; you go through a lot of manipulation of symbols, and yet your
conclusion is clearly wrong from the start (ooh ... I _love_ writing
like this) -- acceleration is indeed necessary somewhere for there to
be a twin paradox.
Argument: take two clocks in relative motion, and remember, we are
forbidden to acceleration either one. Therefore the clocks are in
constant inertial relative motion, and are related in their rest
frames by a Lorentz transform. Well, we all know about Lorentz
transforms, don't we -- there is a reciprocal slowing of time, a feat
made possible by the interweaving of time and space. It all works out
Ok in the end, but neither clock can unambiguously be said to have
lost time wrt the other.
As a special case, we can consider two co-moving clocks. In this
case, in the clocks' rest frame, they remain in synchronization up to
a constant forever.
Further argument: Normally, although I will not absolutely insist
upon it, a "twin paradox" requires two clocks to have been coincident
at an event A and at a second event B. The requirement of coincidence
is to remove any ambiguity about "synchronization". I agree
completely that the clocks do not have to be at mutual rest ...
coincident for some interval of proper time ... it is sufficient that
they pass each other at a single event, at any relative velocity. A
snapshot of the relative times shown at that event is an observer
invariant.
Ok. Now, applying what we have learned above, how can two clocks be
coincident twice? Well, either they remain coincident at all times,
or else they depart from coincidence and then momentarily regain that
holy condition. In order for this to happen, at least one clock must
be accelerated: otherwise they will cross paths exactly once.
Since this seems crystal clear, any further calculation seems
superfluous. What part of my analysis do you disagree with?
<read, read, read>
Oh ... you cheated! You used _three_ clocks. Well, this seems like a
pretty Rube Goldberg "twin paradox", but I guess. The out and back
clock could be replaced with two clocks running hot, straight and
normal, which pass off a token in a kind of relay race. I agree then
that the elapsed proper time on this clock pair would be less than on
a single inertial clock which they crossed at event A and event B,
although it could be argued that the two clocks doing the relay race
were the moral equivalent of one clock doing a sharp acceleration.
Still, your prevarication has the valuable property of showing that it
is not any intrinsic effect of acceleration on the clock which results
in the "paradox", but only on the trajectory.
<Sententious conclusion mode>: Indeed, how could it be otherwise? SR
knows nothing of acceleration, contains no terms in acceleration, and
hence any effects of acceleration in SR must merely be an integrated
compounding of many small increments of constant velocity. To deal
with the effects of acceleration per se on matter we need GR. And
therefore, we would predict in any particular instance of the two
clock twin paradox that the SR result is in fact modified by GR, since
at least one of the clocks must undergo acceleration. So you have
present the SR-clean version in which no clocks undergo acceleration.
Kudos, Al, Kudos (though I choke on them).
Amazing how many iteration the understanding goes through. From the
false claim sometimes seen "We need GR to handle acceleration",
meaning apparently that we must invoke the GR deity whenever the
sacred word "acceleration" appears, to the antithesis that we can in
fact handle a lot about acceleration in a pure SR environment, in
effect by integration over many contiguous inertial frames, yadda,
yadda, to the final triumphant (?) synthesis: we can handle a lot
about acceleration in SR but for a _complete_ account of a process
involving the acceleration of material bodies even in flat space, I
think we must after all invoke GR.
Actually, I'm not 100% sure of the last claim: Is there any "purely
GR-ish" effect related to the acceleration of material bodies in flat
space, or are all physical effects obtained by combining the
predictions of SR with any direct effects of the forces involved on
the body?
Some question just never go away. Damn.
I guess the last question could be summed up by experiment: put any
kind of clock we like in an ultracentrifuge. Spin liberally. Once we
have accounted for (1) the relativistic effects of |u| (magnitude of
speed at the end of the arm) (2) any direct effects of the stress
field on the clock, is there (3) some residue left over for GR, an
"intrinsic effect of acceleration".
Answer.
Edward Green
<snip>
No clock need be accelerated for the Twin Paradox to occur.
<snip>
P.S. Calling your three-clock version the "Twin Paradox" is at least
misleading, like a magician who calls the audiences attention away
from what he is really doing. You should call it the "triplet
paradox", maybe. Only half facetious.
> BOTTOM LINE: Get all three clocks together and compare elapsed
> times.
???
> Elapsed time #2=#3, but elapsed time #2+#3 does not equal #1,
> the local stationary reference frame summation. The sum of #2+#3
> elasped time is only about 4.5% that than of #1's accumulated elapsed
> time. You now have the Twin Paradox without any running clock having
> been accelerated.
Didn't notice this clause before. How do you propose to "get all
three clocks together" without accelerating some of them!!?? Oh... I
see ... yet more Rube Goldbergism. You are using stopwatches ... any
_running_ clock having been accelerated. Smart aleck.
Randy Poe
> Fast mesons live longer than stationary muons. What goes tick tock in a
> meson?
<Spaceman>
"Fast mesons" are a mass in motion and you
don't even see it. Motion = ticker.
Clock worship god sinking. Blub blub.
Research all clocks.
-2*-2 = -4
Pressure of uncharged electrons as
big as basketballs.
LOL.
Yeeha!
</Spaceman>
Uncle Al
>
> George Greene <gre...@eagle.cs.unc.edu> wrote in message news:<xeslm4n...@eagle.cs.unc.edu>...
> > Uncle Al <Uncl...@hate.spam.net> writes:
> > : Nothing runs "slow" in any reference frame.
> All calculations in Special Theory of Relativity are based on the law
> of conservation of momentum and kinetic energy.
Special Relativity is a self-conistent hyperbolic geometry. Physics
is inserted later. Conservation laws are absolutely *absent* from
SR's derivation.
Instead of shitting in our parlour, why don't you learn something
about that which you spew?
If you wish to gainsay conservation laws, you must discredit Noether's
theorem. You don't know shit about Noether's theorem, either. As
Noether's theorem is founded in pure mathematics, I'd say there was a
pretty good bung driven up you backside - with a sledgehammer.
[snip random idiocy]
Uncle Al
>
> Major flaw in your argument:
>
> In order for the jiggers of the clocks of spaceships 1 and 2 to click
> each other on, the two spaceships have to have a certain orientation
> relative to each other.
Bullshit. Look at a joystick - 2(pi) steradians of give. Use a
fiberoptic source and a pinhole photodiode detector as the ships skim
1 millmeter part -no mechanical contact.
[snip hopeless 2-D confusion]
Uncle Al
>
> Uncle Al <Uncl...@hate.spam.net> who lowliest coat tassels I am unworthy to kiss, wrote in message news:<3DB81FA6...@hate.spam.net>...
>
> > "V.Gopal" wrote:
> > >
> > > In Special Relativity Theory the basis of "Twin Paradox" is that
> > > "moving clocks run slow". What is not clear is that, when a 'clock
> > > runs slow' whether its frequency continuously decreases or not. Can
> > > anyone clarify this point?
>
> That would be a second order "running slow", wouldn't it -- an
> acceleration of slowness.
>
> > Nothing runs "slow" in any refernce frame. When otherwise identical
> > clocks - one of which sustained a velocity relative to the other - are
> > brought together to compare, one is seen to have less elapsed time
> > than its twin due to its hyperbolic rotation through 4-space. The
> > skewing factor is sqrt[1-(v^2/c^2)].
> > No clock need be accelerated for the Twin Paradox to occur.
>
> I doubt this. I've seen you make this claim before. Let's take a
> closer look ...
> >
> > Given any achievable velocities V1 and V2 and any finite lightspeed,
> > the sum of the velocities as viewed by any inertial observer cannot
> > exceed
> >
> > (V1 + V2)/[1 + (V1)(V2)/c^2]
>
> What? Given any "achievable velocities" v1 and v2, the sum is bounded
> by 2c. Since the frame in which the sum is 2c - eps is an inertial
> frame, that is your bound: v1 + v2 < 2c.
Newtonian physics and Galilean transforms are empirically invalid
udner relativistic conditions. I don't know how your universe
operates, but in mine and everybody else's the view of lightspeed and
directly opposed velocities in any reference frame cannot exceed
lightspeed - including lightspeed vs. lightspeed. This is trivially
demonstrated in counter-circulating particle accelerators such as CERN
or FermiLab.
[snip incredible bulk of ignorant spew invalidated by common
observation]
The unverse doesn't care what you think, or if you think at all.
Reality is not subject to majority vote. Your crap is religion, and
we all know how well that works. Test of faith!
Uncle Al
Why make it complicated? Each ship has ore, a smelter, and a machine
shop. Accelerate to (+/-)0.999c vs. Clock 1, THEN build the ship's
clock starting from molten whatever. Run the experiment. Write down
the elapsed time number. Blow the clock out the plasma warp drive.
Come back home. The clock NEVER accelerates.
Franz Heymann
"V.Gopal" <vgop...@rediffmail.com> wrote in message
news:38af3945.02102...@posting.google.com...
If a clock's frequency continuously decreases, it needs winding up.
Franz Heymann
bri...@encompasserve.org
> Edward Green wrote:
>>
>> Uncle Al <Uncl...@hate.spam.net> who lowliest coat tassels I am unworthy to kiss, wrote in message news:<3DB81FA6...@hate.spam.net>...
>> >
>> > the sum of the velocities as viewed by any inertial observer cannot
>> > exceed
>> >
>> > (V1 + V2)/[1 + (V1)(V2)/c^2]
>>
>> What? Given any "achievable velocities" v1 and v2, the sum is bounded
>> by 2c. Since the frame in which the sum is 2c - eps is an inertial
>> frame, that is your bound: v1 + v2 < 2c.
>
> Newtonian physics and Galilean transforms are empirically invalid
> udner relativistic conditions. I don't know how your universe
> operates, but in mine and everybody else's the view of lightspeed and
> directly opposed velocities in any reference frame cannot exceed
> lightspeed - including lightspeed vs. lightspeed.
Al, read what you wrote, not what you think you wrote. Ed is
objecting to the former, not the latter.
The vector sum of two velocities, v1 and v2 in a particular
reference frame is itself a vector. It is not, quite, a velocity,
but it is expresed in units of velocity. If the individual
vectors have values whose magnitudes are strictly less than c
then the vector sum will have a magnitude that is strictly
less than 2c.
As I said, this sum is not the velocity of any particular object
in any particular reference frame. Instead, it is the time rate of
change in the (vector) separation between the two objects whose
velocities are v1 and v2 as viewed in the reference frame within
which those objects have those velocities.
Note that even with your intended interpretation (velocity of object
1 in frame in which object 2 is at rest), the formula you give has
a sign error. Two oppositely directed velocities add to give a
combined relative velocity whose magnitude is larger than either
individual velocity. Your formula would have them subtract to give
a relative velocity that is smaller than either. We can forgive
you that since the formula is only valid for the one dimensional
case and we can assume that you were talking about speeds of
colliding particles rather than velocities of overtaking
particles.
The more standard setup for the one dimensional velocity composition
formula is object 1 moving with velocity v1 (in some rest frame) and
object 2 moving with velocity v2 in the frame within which v1 is
at rest. The formula you gave then gives the velocity of v2 in
the rest frame.
(The above sign error creeps in when you casually switch the roles
of object 1 and the rest frame and forget to change v1 to -v1)
> This is trivially
> demonstrated in counter-circulating particle accelerators such as CERN
> or FermiLab.
No. The disagreement is more basic than that.
John Briggs
bri...@encompasserve.org
> The vector sum of two velocities, v1 and v2 in a particular
> reference frame is itself a vector. It is not, quite, a velocity,
> but it is expresed in units of velocity. If the individual
> vectors have values whose magnitudes are strictly less than c
> then the vector sum will have a magnitude that is strictly
> less than 2c.
>
> As I said, this sum is not the velocity of any particular object
> in any particular reference frame. Instead, it is the time rate of
> change in the (vector) separation between the two objects whose
> velocities are v1 and v2 as viewed in the reference frame within
> which those objects have those velocities.
Damn. I accuse Uncle Al of a sign error and I make the exact same
sign error myself.
Take the _difference_ of those velocties, not their sum if you
want the time rate of change in their vector separation.
John Briggs
larry
Sorry Al, I didn't mean to cause you to have a brain fart.
Larry
>
>
Daryl McCullough
>
>Uncle Al <Uncl...@hate.spam.net> wrote:
>> No clock need be accelerated for the Twin Paradox to occur.
>
>I doubt this. I've seen you make this claim before. Let's take a
>closer look ...
>Oh ... you cheated! You used _three_ clocks. Well, this seems like a
>pretty Rube Goldberg "twin paradox", but I guess. The out and back
>clock could be replaced with two clocks running hot, straight and
>normal, which pass off a token in a kind of relay race. I agree then
>that the elapsed proper time on this clock pair would be less than on
>a single inertial clock which they crossed at event A and event B,
>although it could be argued that the two clocks doing the relay race
>were the moral equivalent of one clock doing a sharp acceleration.
Yes, but the difference is that in the three-clock case, no
clock is physically accelerated. That should put an end to
the idea that time dilation is something physical
that happens to clocks when they accelerate.
>Still, your prevarication has the valuable property of showing that it
>is not any intrinsic effect of acceleration on the clock which results
>in the "paradox", but only on the trajectory.
Exactly. In Special Relativity, time dilation is a feature of
spacetime, not a feature of clocks.
>Indeed, how could it be otherwise? SR
>knows nothing of acceleration, contains no terms in acceleration, and
>hence any effects of acceleration in SR must merely be an integrated
>compounding of many small increments of constant velocity. To deal
>with the effects of acceleration per se on matter we need GR.
No, that's not right. In flat spacetime (regardless of whether anything
is accelerating) GR reduces to SR. GR tells you nothing about the
effects of acceleration on clocks that isn't already present in SR.
>Amazing how many iteration the understanding goes through. From the
>false claim sometimes seen "We need GR to handle acceleration",
>meaning apparently that we must invoke the GR deity whenever the
>sacred word "acceleration" appears, to the antithesis that we can in
>fact handle a lot about acceleration in a pure SR environment, in
>effect by integration over many contiguous inertial frames, yadda,
>yadda, to the final triumphant (?) synthesis: we can handle a lot
>about acceleration in SR but for a _complete_ account of a process
>involving the acceleration of material bodies even in flat space, I
>think we must after all invoke GR.
You need one more iteration. If space is flat, there is no
need for GR, and, in fact, GR gives you nothing more than
SR in that case.
>Actually, I'm not 100% sure of the last claim: Is there any "purely
>GR-ish" effect related to the acceleration of material bodies in flat
>space, or are all physical effects obtained by combining the
>predictions of SR with any direct effects of the forces involved on
>the body?
No. There is no purely GR-ish effect in flat spacetime.
Maybe it would help to show you a series of steps in going
from SR to GR:
1. SR in which only inertial coordinates are used and
the only problems considered are those that don't involve
acceleration.
2. Generalize to allow accelerations (but stick to using
inertial coordinate systems).
3. Generalize to arbitrary coordinates (but still letting
spacetime be flat).
4. Generalize to fixed curved spacetime.
5. Allow matter and energy to affect spacetime curvature.
Exactly where in the progression from 1-5 the theory becomes GR
is a matter of terminology. But I don't think any physicist would
say that the transition from 1 ==> 2 involves GR. Einstein
developed SR specifically for electrodynamics, in which
charges are being accelerated by electromagnetic forces. It
would be pretty much a failure if SR didn't handle accelerations.
The only thing that makes handling accelerations difficult is
that you have to actually worry about what the laws of physics
are governing accelerations. If you leave out accelerations, then
you can forget actual physical properties of matter, and just
work with idealized clocks and rulers.
Going from 2 ==> 3 is purely mathematical.
If you know how to do SR using inertial coordinates, then you can
figure out how to do SR using noninertial coordinates. It's just
a matter of performing a coordinate change, which is pure
math.
Going from 3 ==> 4 involves a tiny amount of additional
physics: you need to make assumptions about how curvature affects
things. The minimal assumption is that given by the "equivalence
principle": you assume that SR holds approximately in any small
region of spacetime. This allows you to adopt the math developed
in stage 3 for use in stage 4.
Going from 1 ==> 4 was pretty straight-forward once he had the basic idea
that gravity is spacetime curvature. All the paradoxes and thought
experiments of relativity involving accelerating clocks and rockets
and so forth are all covered by 4.
Going from 4 ==> 5 is really hard, and that's the part that took
Einstein several years to do. But this final step, to true GR, is
irrelevant for most layman discussions of relativity.
The biggest misconception about the relationship between
SR and GR is the idea that GR tells us how to handle
accelerations in SR. That's exactly backwards. GR instead
assumes that accelerations in small regions of spacetime
work out the same way they do in SR. So the import of the
equivalence principle is that it allows us to do gravitational
problems using SR, not that it allows us to do acceleration
problems using GR.
>I guess the last question could be summed up by experiment: put any
>kind of clock we like in an ultracentrifuge. Spin liberally. Once we
>have accounted for (1) the relativistic effects of |u| (magnitude of
>speed at the end of the arm) (2) any direct effects of the stress
>field on the clock, is there (3) some residue left over for GR, an
>"intrinsic effect of acceleration".
If your centrifuge is floating in flat spacetime, then GR doesn't
predict any effect that is not accounted for by SR. Both GR and
SR predict the same thing:
Elapsed time on clock =
Integral of square-root(1-(v/c)^2) dt
--
Daryl McCullough
Ithaca, NY
James Hunter
"Daryl McCullough" <da...@cogentex.com> wrote in message
news:apbut...@drn.newsguy.com...
> null...@aol.com (Ed Green) says...
> >>
> >Oh ... you cheated! You used _three_ clocks. Well, this seems like a
> >pretty Rube Goldberg "twin paradox", but I guess. The out and back
> >clock could be replaced with two clocks running hot, straight and
> >normal, which pass off a token in a kind of relay race. I agree then
> >that the elapsed proper time on this clock pair would be less than on
> >a single inertial clock which they crossed at event A and event B,
> >although it could be argued that the two clocks doing the relay race
> >were the moral equivalent of one clock doing a sharp acceleration.
>
> Yes, but the difference is that in the three-clock case, no
> clock is physically accelerated. That should put an end to
> the idea that time dilation is something physical
> that happens to clocks when they accelerate.
Well, it doesn't. Since the whole premise of *Relativity*
has nothing really to do with either space contraction or
time dilatiion.
As Einstien wrote in *his* version of Relativity, it goes:
*Space-time* is not something that happens to moron scientists when they
are resting.
Uncle Al
>
> null...@aol.com (Ed Green) says...
> >
> >Uncle Al <Uncl...@hate.spam.net> wrote:
>
> >> No clock need be accelerated for the Twin Paradox to occur.
> >
> >I doubt this. I've seen you make this claim before. Let's take a
> >closer look ...
>
> >Oh ... you cheated! You used _three_ clocks. Well, this seems like a
> >pretty Rube Goldberg "twin paradox", but I guess. The out and back
> >clock could be replaced with two clocks running hot, straight and
> >normal, which pass off a token in a kind of relay race. I agree then
> >that the elapsed proper time on this clock pair would be less than on
> >a single inertial clock which they crossed at event A and event B,
> >although it could be argued that the two clocks doing the relay race
> >were the moral equivalent of one clock doing a sharp acceleration.
>
> Yes, but the difference is that in the three-clock case, no
> clock is physically accelerated. That should put an end to
> the idea that time dilation is something physical
> that happens to clocks when they accelerate.
Good Lord! Somebody else knows which tin has the Shinola.
[snip]
> >I guess the last question could be summed up by experiment: put any
> >kind of clock we like in an ultracentrifuge. Spin liberally. Once we
> >have accounted for (1) the relativistic effects of |u| (magnitude of
> >speed at the end of the arm) (2) any direct effects of the stress
> >field on the clock, is there (3) some residue left over for GR, an
> >"intrinsic effect of acceleration".
>
> If your centrifuge is floating in flat spacetime, then GR doesn't
> predict any effect that is not accounted for by SR. Both GR and
> SR predict the same thing:
>
> Elapsed time on clock =
> Integral of square-root(1-(v/c)^2) dt
Straightforward but insensitive experiment: Generate some suitably
short half-life unambiguously countable (via 4(pi)steradian two-photon
coincidence) radioisotope like 0-15 (2.03 min), N-13 (9.97 min), C-11
(20.3 min), or F-18 (109.8 min). Apportion the solution into two
batches, one to sit on the bench and the other to whiz around in a
Beckman-Coulter Optima MAX ultracentrifuge at one million gees for an
hour or two. Run that puppy.
Will you see the effect of only velocity (SR) slowing time for the
centrifuged sample, or will the pseudogravitational field (GR) add
in? We expect only SR.
Simple experiment: Do an external Mossbauer resonance experiment with
a sample in the running centrifuge rotor inside rim (correcting for
transverse Doppler shift) vs. an identical piece sitting atop the hub
(same angular velocity). Emitter and detector on opposite sides of
the rotor is even nicer - same pseudogravitation, double the velocity
difference - or are they moving at all vs. one another? "8^>)
George Greene
: Blow the clock out the plasma warp drive.
: Come back home. The clock NEVER accelerates.
Getting blown out of a plasma warp drive will
usually cause your velocity to change.
Daryl McCullough
>
>Daryl McCullough wrote:
>> Yes, but the difference is that in the three-clock case, no
>> clock is physically accelerated. That should put an end to
>> the idea that time dilation is something physical
>> that happens to clocks when they accelerate.
>
>Good Lord! Somebody else knows which tin has the Shinola.
I have no idea what that means, but since I think I was
agreeing with you, I'll take that as a compliment.
Uncle Al
>
> Uncle Al <Uncl...@hate.spam.net> writes:
>
> : Blow the clock out the plasma warp drive.
> : Come back home. The clock NEVER accelerates.
>
> Getting blown out of a plasma warp drive will
> usually cause your velocity to change.
It won't be a clock any more and nobody will look at it anyway. You
really are thick.
George Greene
: > > : Nothing runs "slow" in any reference frame.
As far as I'm concerned, the 3-clock experiment
you posited CONFIRMS that moving clocks run
slow; it does not refute it. When you bring
your two pieces of paper announcing what times
the moving clocks ran to, back to the place
where "our" clock (clock 1) has ITS time,
both of the numbers on those pieces of paper
are a lot lower than the time on our clock
-- or than half the time on our clock--
which IS what they WOULD say if those clocks
were NOT running slow.
Franz Heymann
"Randy Poe" <rp...@nospam.com> wrote in message
news:apbju...@enews1.newsguy.com...
What's the bet Spaceman does not thank you for saving him some typing?
Franz Heymann
James Hunter
> George Greene wrote:
> >
> > Uncle Al <Uncl...@hate.spam.net> writes:
> >
> > : Blow the clock out the plasma warp drive.
> > : Come back home. The clock NEVER accelerates.
> >
> > Getting blown out of a plasma warp drive will
> > usually cause your velocity to change.
>
> It won't be a clock any more and nobody will look at it anyway. You
> really are thick.
That only happens in Gandankerville though, where
light is actually used by morons as a speed limit.
But, since it's irrelevant to technology, just like Relativity is,
the spontaneously religous are always told that
school bells, church bells, and Born Again
Geometric Revivalist Ho Downs don't count as clocks.
Richard
>
> Uncle Al wrote:
> >
> > "V.Gopal" wrote:
> > >
> > > In Special Relativity Theory the basis of "Twin Paradox" is that
> > > "moving clocks run slow". What is not clear is that, when a 'clock
> > > runs slow' whether its frequency continuously decreases or not. Can
> > > anyone clarify this point?
> >
> > Nothing runs "slow" in any refernce frame. When otherwise identical
> > clocks - one of which sustained a velocity relative to the other - are
> > brought together to compare, one is seen to have less elapsed time
> > than its twin due to its hyperbolic rotation through 4-space. The
> > skewing factor is sqrt[1-(v^2/c^2)].
> >
> > experiment.
> >
> > CLOCK 1: That's our clock. It sits stationary in our inertial
> > reference frame with a little jigger sticking out. Touch the jigger
> > and the "off" state becomes "on" or the "on" state becomes "off."
> > Clock 1 is "off."
> >
> > CLOCK 2: In a spaceship traveling at 0.999c relative to our
> > inertial frame of reference. Clock 2 is "off." It skims past Clock
> > 1, the jiggers touch, both Clocks 1 and 2 are now "on" and
> > synchronized.
> >
> > CLOCK 3: In a spaceship traveling at 0.999c relative to our
> > inertial frame of reference, but 180 degrees counter in direction to
> > Clock 2. Clock 3 is "off." Some arbitrary time after Clocks 1 and 2
> > synchronize and turn "on" by touching, Clocks 2 and 3 brush past each
> > other, touching jiggers. Clock 2 is now "off," Clock 3 is now "on."
> >
> > CLOCK 1: That's our clock. It sits stationary in our inertial
> > reference frame with a little jigger sticking out. Clock 3 rushes
> > past, jiggers touch. Clocks 3 and 1 are now off. All clocks are
> > off. No clock has accelerated while "on."
> >
> > the local stationary reference frame summation. The sum of #2+#3
> > elasped time is only about 4.5% that than of #1's accumulated elapsed
> > been accelerated.
>
> Clocks do not measure the passage of time, they 'register' an internal
> velocity (of some mass or system of mass) times it's displacement,
Oops! Make that inverse of velocity times displacement.
> either linear or angular depending upon the type of clock, an internal
> velocity that must change in order for the registered 'ticks' to get out
> of sync with another clock. A change in velocity does not a change in
> time equal. Now suppose I adopt the motion of an elastic ball between to
> walls as my time-piece:
> 1) How will this clock differ fundamentally from any other clock?
> 2) Since when will an acceleration of the elastic ball constitute a
> change in the rate that I am passing through time, rather than
> constituting simply an increase in its intrinsic frequency wrt time?
>
> Richard
Richard
George Greene
: George Greene wrote:
: >
: > Uncle Al <Uncl...@hate.spam.net> writes:
: >
: > : Blow the clock out the plasma warp drive.
: > : Come back home. The clock NEVER accelerates.
: >
: > Getting blown out of a plasma warp drive will
: > usually cause your velocity to change.
:
: It won't be a clock any more
Then it won't be a frame any more either, according
to your previous equation of a clock with a frame.
: and nobody will look at it anyway.
OK, fine, they only look at the little piece of
paper or whatever emitted by the clock after it
shuts off, telling how long it ran. That doesn't change
anything. The number on that piece of paper is still
smaller than (half of) the number on the piece of paper
coming out of clock 1. In other words, that clock
really DID run slow.
George Greene
: >> Yes, but the difference is that in the three-clock case, no
: >> clock is physically accelerated.
While it's running. Or even existing, if he
wants to keep going that far.
: >> That should put an end to
: >> the idea that time dilation is something physical
: >> that happens to clocks when they accelerate.
Hardly. It was about FRAMES, NOT clocks.
Which Uncle Al wilfully obscured first by
claiming that clocks ARE frames and then insisting
that clocks could be destroyed (frames can't).
His originally claim was that the usual maxim that
"moving clocks run slow" was disprovable. This
thought experiment doesn't disprove that; it proves it.
Seconds are "longer" for the moving clock and
the faster it is going the longer they are. In other
words, the more they have been dilated. And they
GOT dilated BY/DURING the acceleration. Which
was happening to the FRAME (or the ship that the
clock later got built on, right before it got
turned on), NOT the clock.
Pierre Asselin
[Three-clock version of the twin paradox]
Hey, that's good. Really good!
Also, I salute your ability to draw out idiots with a substantive
post. Is this normal in sci.physics? I'm reading the thread from
sci.logic .
Richard
>
> Richard wrote:
> >
> > Uncle Al wrote:
> > >
> > > "V.Gopal" wrote:
>
> > When you can define time, then maybe your input will be interesting.
> > Clocks do not measure the passage of time, they 'register' an internal
> > velocity (of some mass or system of mass) times it's displacement,
> > velocity that must change in order for the registered 'ticks' to get out
> > of sync with another clock.
>
> that is your clock. Why don't you tell us where the "internal
> velocity" is in radioactivity?
It's not too fucking complicated that even you can't understand Al, but
only agglomerations of quanta produce radioactive decay. Which of the
involved quanta has zero velocity shit for brains? Controlled fission,
hmmm Al, how the hell did that happen I wonder, I mean, radioactive
decay is independently spontaneous, uncaused, isn't it? Git.
Richard
Sam Wormley
>
> When you can define time, then maybe your input will be interesting.
> Clocks do not measure the passage of time, they 'register' an internal
> velocity (of some mass or system of mass) times it's displacement,
> either linear or angular depending upon the type of clock, an internal
> velocity that must change in order for the registered 'ticks' to get out
> of sync with another clock.
Time
o regarded as a coordinate dimension and required by relativity
theory, along with three spatial dimensions, to
specify completely the location of any event.
o The Physical Basis of the Direction of Time
http://math.ucr.edu/home/baez/time/time.htmlfourth dimension
Richard
Time
As perceived: A motion through ordered changes in state of the universe.
As it enters physics: The logical displacement of the initial state of a
closed system and the state of the same system through an arbitrary and
homogenous sequence of changes. Those cyclic changes in a sub-system
(also virtually closed) in particular being regarded as "regular", and
arbitrarily designated as a standard unit of change. The homogenous
sequence of ordered microscopic changes (events) in the universe
constitute a universal time-line, "moved" through equally by all
particles, since all particles simultaneously exist in every state
subtending any "duration".
Richard
Sam Wormley
Mumbo Jumbo, rhubarb rhubarb Tickety bubarb yak yak...
Uncle Al
One might suspect that a superior mentality would draw out an angry
otherwise disenfranchised mob. In sci.physics *any* working mentality
generates shockwaves in kind. Cranks, crackpots, and psychotics are
like eunuchs in a brothel. Their mouths hang open drooling spit and
they loudly boast about their prowess, but there are no facts arising
- and slapping on a testoterone patch is like administering medicine
to the dead.
Physics is self-consistent. Physics contains no mistakes. However,
physics is ripe for attack at its postulates (as was Euclid when
elliptic and hyperbolic geometries appeared),
http://www.mazepath.com/uncleal/eotvos.htm
Do something naughty to physics.
http://www.mazepath.com/uncleal/eotvos.pdf
The short form.
Soembody should look.
Big Bird
> Indeed, how could it be otherwise? SR
> knows nothing of acceleration, contains no terms in acceleration, and
> hence any effects of acceleration in SR must merely be an integrated
> compounding of many small increments of constant velocity. To deal
> with the effects of acceleration per se on matter we need GR.
False.
> Actually, I'm not 100% sure of the last claim: Is there any "purely
> GR-ish" effect related to the acceleration of material bodies in flat
> space, or are all physical effects obtained by combining the
> predictions of SR with any direct effects of the forces involved on
> the body?
>
> Some question just never go away. Damn.
They would go away, if only you were willing to take the time (and
invest the effort) to read (and work your way) through MTW.
If you are comfortable with special relativity, go directly to chapter
6 ("accelerated observers"). Read the chapter and work out all the
problems. There you have SR dealing with acceleration. No big deal.
Ronald Stepp
news:pbvjruckkb5vcg4dh...@4ax.com...
> Hey Al. How'd you like the picture I posted of you in
> alt.binaries.pictures.misc ??? Pretty cool eh? :-]
>
> You should look.
Explain why you think he "should" look?
V.Gopal
express or convey continuously and uniformly decreasing rate of
counting. Can we know when we reach zero if the rate of counting
decreases uniformly and continuously?
Here 'counting' does not divide time into equal intervals and in this
case because there is no linear or angular displacement, time appears
to 'shrink' continuously. How can we canvey rate of shrinkage of time?
Edward Green
> null...@aol.com (Ed Green) says...
<cut to the chase>
> >Indeed, how could it be otherwise? SR
> >knows nothing of acceleration, contains no terms in acceleration, and
> >hence any effects of acceleration in SR must merely be an integrated
> >compounding of many small increments of constant velocity. To deal
> >with the effects of acceleration per se on matter we need GR.
>
> No, that's not right. In flat spacetime (regardless of whether anything
> is accelerating) GR reduces to SR. GR tells you nothing about the
> effects of acceleration on clocks that isn't already present in SR.
To save time, let me repeat what I arrived at at the end of my post.
First, I claim I am a veteran adherent of the "SR can too handle
acceleration" insight. E.g., I realized a long time ago that claims
that we need GR to analyze the Ehrenfest disk are nonsense.
Now, as so often happens -- not more than 10^9 times since I started
posting -- even when I _claim_ I grok some
objection/reservation/caveat, but suggest something subtly different,
it is assumed by a person who for some reason does not see the subtle
difference that I am mistaken about my mistake, and stuck on the first
iteration.
In other words, when I repeat my question, you may think I am still
asking if "SR is competent to handle accelerated objects" in a dumb
old way, rather than the smart new way I claim I am asking the
question.
My path is something like this
(1) mythical prehistory -- need GR to handle accelerated bodies
(I don't think I ever actually believed this)
(2) pre-current state -- acceleration in SR can be handled by a
combination of integration (effect of a sequence of instantaneous rest
frames) plus material effects (stress, etc).
(3) glimmer of nuance --
I have a momentary doubt that both of these programs correctly applied
are sufficient to completely exhaust any "GR effects" of accelerated
object in flat spacetime.
Now, I may always be wrong, but I claim I am probably wrong for a more
subtle reason than whichever you first suggest. :-)
Let's look at our friend the Ehrenfest disk again. We proceed in flat
space in an inertial frame of reference, and consider a disk spinning
at steady state, which has already resolved all its inner length
contraction/stress/transient issues.
Now, on the theme of "kinematics still works as before in fixed
inertial frame", all points at radius r from the axis have
instantaneous speed u = rw, and instantaneous acceleration a = rw^2.
Ok. Now, suppose we choose to fix u, while allowing r to shrink and w
to increase. We see that while u remains fixed, a will scale with
omega.
Now, lets consider the effect on clocks at this radius. First, during
any small time interval dt in the inertial frame, the clocks are
moving with a given u, hence should appear to be running slower
"special relativistically".
Agree?
Second, because of the increasing acceleration, the stress on the
clocks will increase, which may affect their time keeping ability
purely "mechanically". I.e. (hold your fire, Daryl), they may undergo
physical effects which we would not refer to as "time dilation", but
nonetheless affect the rate at which the clocks run compared to a
unstressed reference.
Agree?
So, we have possibly mechanically affected clocks further running at
an apparently aberrant rate, even accounting for the mechanical
effects, via Lorentz transformation.
I hope you agree so far.
Now, according to the programme "SR contains all effects of
acceleration in flat spacetime", we are apparently finished. There
are no more possible physical effects on the clocks, and hence, first
correcting for mechanical effects of acceleration, we predict any
further disagreement with clocks at rest in the inertial frame
according to the Lorentz transformation.
Now, have we exhausted the possible effects of acceleration on clocks,
or not? You would claim that we have, and I hope I have at least
stated your programme fairly and convincingly. I am however not 100%
convinced we have exhausted the physical description. Here's why.
First, back to pure SR a moment. I claim, though I have not struggled
with this in a while, that _most_ of the effects of SR can be
predicted macroscopically by analyzing the behavior of a flotilla of
space ships which keep themselves in formation by exchanging timed
radar pulses. In a fixed inertial frame, the observer sees the
flotilla is making "mistakes" by ignoring the differing forward,
backward and lateral propogation of light in their own rest frame.
_We_ see the effects of their relative motion past us, but they
blithly ignore it.
Almost, but not quite "explain" SR, I think. The catch is, in order
to make this picture consistent, we have to reach inside systems on
the ships we have not analyzed, and _postulate_ their adherence to SR.
And I believe, if we then analyzed these smaller systems, we would
find yet smaller systems within 'em which we again had to resort to
postulation on. So we seem to be onto something, but we can't quite
close the loop, and ultimate must adopt the Lorentz invariance of
physics as a postulate, maddeningly hinted at by a kind of infinite
recursion.
Ok.
Now, I'm thinking of your nice analysis of gravitational redshift in
terms of the bow and stern of an accelerating space ship, and doppler
effects. Here is a case where we get the gravitational/accelerational
equivalence effects of GR for free from SR. This would tend to
substantiate your claim that all we need is SR to analyze any possible
effect of acceleration in flat space time. But I'm also thinking
about this infinite recursion thing ...
Proposed moral: there may be acceleration effects on matter, beyond
those predicted macroscopically by a close application of SR to
analyzing the components (like the space ship doppler red shit), and
beyond continuum mechanistic constituent relation effects ... like
stress strain, etc.
These might correspond to something like "stresses and strain in the
nuclei", below our level of analysis with SR, which would in fact need
the machinery of GR to tease out, albeit we remained in flat
gravitation free space.
I'm not saying this is necessarily so -- I'm trying to argue that it
may not be altogether stupid to consider the possibility ("You know,
what professor Einstein says is not so stupid ... " :-).
> >Amazing how many iteration the understanding goes through. ...
> You need one more iteration. If space is flat, there is no
> need for GR, and, in fact, GR gives you nothing more than
> SR in that case.
I understand what you are saying, I claim, so you must look for my
reservation on some other plane.
> No. There is no purely GR-ish effect in flat spacetime.
Maybe. I only claim, via above analysis, that my doubt is
not-so-stupid, though it may appear tautological that SR is GR in flat
spacetime, so there is nothing more to say. We may lose something in
the simpler machinery.
Anyway, here is a thought experiment -- I have no preconceived idea of
what it may illustrate, but I would like to know what you think. I
think somebody recently asked this besides me.
Consider an Ehrenfest disk again, now masquerading as a centrifuge,
and consider the clocks at r, again. Are you certain we will have
exhausted any effects on these clocks tending to upset their
synchronization with inertial clocks by first considering their speed,
next an mechanical effects of the centrifugal acceleration?
If we have, then what has happened to the equivalence principle?
These clocks appear to be at the bottom of a gravity well equivalent
wrt a clock on the hub, but I don't see any possibility for an
equivalent effect ... we don't have Doppler any more to appeal to,
unless some kind of relativistic transverse Doppler effect?
Another possibility is that a sufficiently fine "mechanical" analysis
of the effects of acceleration would in effect steal from the
machinery of GR and significant residual effect -- but possibly not to
an endless number of zeros.
I'm going to leave any comments on the rest out for brevity -- but I
again protest that I have long understood that SR can indeed handle
accelerated matter -- I just for some reason feel uncertainty that we
have exhausted the subject.
Edward Green
> Edward Green wrote:
> >
> > Uncle Al <Uncl...@hate.spam.net> who lowliest coat tassels I am unworthy to kiss, wrote in message news:<3DB81FA6...@hate.spam.net>...
> > > Given any achievable velocities V1 and V2 and any finite lightspeed,
> > > the sum of the velocities as viewed by any inertial observer cannot
> > > exceed
> > >
> > > (V1 + V2)/[1 + (V1)(V2)/c^2]
> >
> > What? Given any "achievable velocities" v1 and v2, the sum is bounded
> > by 2c. Since the frame in which the sum is 2c - eps is an inertial
> > frame, that is your bound: v1 + v2 < 2c.
>
> Newtonian physics and Galilean transforms are empirically invalid
> udner relativistic conditions. I don't know how your universe
> operates, but in mine and everybody else's the view of lightspeed and
> directly opposed velocities in any reference frame cannot exceed
> lightspeed - including lightspeed vs. lightspeed. This is trivially
> demonstrated in counter-circulating particle accelerators such as CERN
> or FermiLab.
>
> [snip incredible bulk of ignorant spew invalidated by common
> observation]
Same to you, Al, you insulting sonofabitch.
I merely pointed out from your ambiguous sentence that the maximum
speed difference between two arbitrary velocities is 2c in any
inertial frame. That's c to the right of you and c to the left of
you. Get it? What that has to do with the empirical invalidity of
Newtonian physics and Galilean transforms is beyond me, and any
thinking individual.
Aha ... I see your idiocy. You are one of those people who are
completely blind to the frame dependence of "relative velocity".
Hell, not only are you blind to it, you even stated the concept in
equivalent words, and _still_ screwed it up. I quote from the
infallible master:
"the sum of the velocities as viewed by any inertial observer"
Bizarre. You suffer from the "relative velocity must be stated in
rest frame of one of two bodies" disease so badly that even if _you_
happen to state an equivalent form which leaves your sacred semantic
"relative velocity" untouched and inviolate, you unconsciously
translate it back to your form, and so spew nonsense. If a particle
moves to my right with u2 = c - e1, and if a second particle moves to
my left with u2 = c - e2, then what is the bound on u1 + u2?
I'll give you time to think about this weighty proposition.
Logic impaired half-bakeds like you make one more sympathetic to the
non-standard logic-half-bakes. You have about their wit and wisdom,
and so there is a fit meeting of the minds. So to speak.
Relative velocity v1 - v2 is sensibly viewed as a physical object with
frame dependent representation. Duh. And, given a frame in which we
represent the velocity of particle 1 as v1 and the velocity of
particle 2 as v2, guess what the representation of "relative velocity"
is in that frame? I know you can do it, unless that chemistry
accident fried your brain as well as your skin.
But oh, the beauty of it ... even given that askking for a frame
dependent representation of "relative velocity" is like asking a
Catholic to consider the sexual relation of the virgin to the Holy
Spirit, you yourself came up with an alternate formulation of the
heretical concept.
Oh, what the hell do I care what you think. You may once have been a
brilliant man, but now you are a bitter old spewpot.
Edward Green
Coming from that character assassin, I wouldn't take any sign of
agreement as a compliment.
Uncle Al has developed a severe psychological disorder, possibly
occasioned by an undiagnosed organic brain lesion, causing him to
gratuitiously insult people exhibiting any shade of even temporary
doubt or disagreement with anything which drips from his putrid bile
spewing lips, even in vehicles which both begin and end in, however
severly misplaced, compliments -- kind of an ascii Turet's syndrome.
I independently recognized the utility of Al's construction, though I
am not sympathetic with your characterization including the
tendentious "physical", but once mildly point out something in
relativistic kinematics which he was not prepared immediately to grasp
and he trips off line in some kind of school boy insult session --
like Paul Lutus, before degeneration finally mercifully curtailed his
posting activity altogether.
Too much organic solvent absorbed through the skin, maybe.
Prai Jei
meetings, and you won't get into complications over interactions between the
clocks.
May I refer all doubters to the little book "Relativity and Common Sense" by
Hermann Bondi (Heinemann 1965) which sets everything out logically with
minimal use of heavy mathematics.
"Uncle Al" <Uncl...@hate.spam.net> wrote in message
news:3DB81FA6...@hate.spam.net...
> [snip twin paradox experiment setup]
Richard
Can you provide a consistent reversal of two events with respect to two
inertial frames? Do not the same events occur in the universe wrt the
twins during the time between their departure and the time of their
reunion on Earth? How can you say that each has progressed through time
at different rates when the time that they have moved through is
perfectly equal from every FOR? Though the time that was "registered" by
each may differ, this does not detract from the reality that they were
moving through time at equal rates, it shows only that orbits and cyclic
phenomenon in general are subject to physical change, which is no less
the "very" basis of any type of kinematics. This is the reason that an
accelerated clock is not a valid standard. As an analogy an an the
acceleration and/or change in temperature and/or external pressure
acting on a meter stick, results in a stick that no longer registers the
unit meter correctly, and if launched into orbit where the ambient field
differs then the same applies. Real clocks are just meter sticks in
motion about an axis, is this really that difficult for you guys to
grasp? You are so wrapped up in the abstract relationships between
manufactured units that you have lost all touch with fundamental
reality. The solution is always hidden in the details, those fucking
details;-)
Richard
http://www.cswnet.com/~rper
Franz Heymann
"Richard" <no_mail...@yahoo.com> wrote in message
news:3DB9E8E0...@yahoo.com...
> Uncle Al wrote:
> >
> > Richard wrote:
> > >
> > > Uncle Al wrote:
> > > >
> > > > "V.Gopal" wrote:
> > [snip]
> >
> > > When you can define time, then maybe your input will be
interesting.
> > > Clocks do not measure the passage of time, they 'register' an
internal
> > > velocity (of some mass or system of mass) times it's displacement,
> > > either linear or angular depending upon the type of clock, an
internal
> > > velocity that must change in order for the registered 'ticks' to
get out
> > > of sync with another clock.
> >
> > Radioactivity, shithead. You look at the declining rate of decay
and
> > that is your clock. Why don't you tell us where the "internal
> > velocity" is in radioactivity?
>
> It's not too fucking complicated that even you can't understand Al,
but
> only agglomerations of quanta produce radioactive decay.
Not on your nellie. Study the nature of the weak interaction before
committing further blunders in ignorance.
> Which of the
> involved quanta has zero velocity shit for brains?
Tell us which quanta are involved where. Here is the typical process:
n -> p + e + nu-e-bar
> Controlled fission,
> hmmm Al, how the hell did that happen I wonder, I mean, radioactive
> decay is independently spontaneous, uncaused, isn't it? Git.
You don't need fission, controlled or otherwise, to make a clock based
on radioactive decay.
You are out of your depth and it shows.
Franz Heymann
Franz Heymann
Philosophese mumbo jumbo for saying that time is what is measured by
counting the cycles of a repetitive process.
Franz Heymann
Franz Heymann
"V.Gopal" <vgop...@rediffmail.com> wrote in message
news:38af3945.02102...@posting.google.com...
> "Franz Heymann" <Franz....@btopenworld.com> wrote in message
news:<apbp93$j5u$2...@knossos.btinternet.com>...
> > "V.Gopal" <vgop...@rediffmail.com> wrote in message
> > news:38af3945.02102...@posting.google.com...
> > > In Special Relativity Theory the basis of "Twin Paradox" is that
> > > "moving clocks run slow". What is not clear is that, when a 'clock
> > > runs slow' whether its frequency continuously decreases or not.
Can
> > > anyone clarify this point?
> >
> > If a clock's frequency continuously decreases, it needs winding up.
> >
> > Franz Heymann
> It needs no winding up, let it stop. What I want to know is how do we
> express or convey continuously and uniformly decreasing rate of
> counting. Can we know when we reach zero if the rate of counting
> decreases uniformly and continuously?
> Here 'counting' does not divide time into equal intervals and in this
> case because there is no linear or angular displacement, time appears
> to 'shrink' continuously. How can we canvey rate of shrinkage of time?
I have not a clue as to what you might mean.
I do have a strong suspicion that you don't know either.
Franz Heymann
Franz Heymann
[...]
> >
> > When you can define time, then maybe your input will be interesting.
> > Clocks do not measure the passage of time, they 'register' an
internal
> > velocity (of some mass or system of mass) times it's displacement,
>
> Oops! Make that inverse of velocity times displacement.
You nneed not have bothered. It is still nonsense.
Franz Heymann
Franz Heymann
"Edward Green" <null...@aol.com> wrote in message
news:2a0cceff.02102...@posting.google.com...
I look forward to reading how Uncle Al responds to that. {:-)
Ed, there is no such concept in physics as a "relative velocity" in the
abstract. The concept is restricted to such situations as "The velocity
of A relative to B" or "The velocity of B relative to A". The former is
a measurement made in the frame in which B is at rest. Vice versa for
the latter.
The situation under dicussion which leads to a maximum speed of 2c does
*not* involve the velocity of anything relative to anything else. It is
a "velocity of approach" of two objects *relative to me*, i.e. in the
frame in which *I* am stationary.
[...]
> Relative velocity v1 - v2 is sensibly viewed as a physical object with
> frame dependent representation
You are simply privately redefining the concept of an approach velocity
of two objects, as measured in the frame in which I am stationary. It
is unnecessary.
Franz Heymann
Uncle Al
>
> You don't even need jiggers. Just note the clock times at the various
> meetings, and you won't get into complications over interactions between the
> clocks.
That is what the jiggers do. The only way to synchronize two clocks
is for them to be "local." Touching does the job without argument.
One wouldn't have two spaceships traveling 180 degrees head on at
0.999c skim within a millimeter of each other in the real world for
fear of insurance premiums skyrocketing. It does make an entirely
satisfactory thought experiment.
"Looking" ship to ship won't do it for obvious reasons and
argumentative ones.
Special Relativity is a self-consistent hyperbolic geometry. It
cannot be "disproven" any more than Euclid can be disproven. Both are
rigorously derived and neither contains any errors. However,
postulates are always ripe for attack!
Plane geometry is the logic of zero curvature (Euclid's Fifth
Postulate). If we assume positive or negative curvatures we get
elliptic and hyperbolic geometries whose limiting zero-curvature cases
are Euclid. Newton tacitly assumed lightspeed is infinite. If we
assume lightspeed is c we get Special Relativity, whose limiting case
for low velocities is Newton.
General Relativity assumes the Equivalence Principle, that inertial
(push a car) and gravitational (lift a car) masses are rigorously
identical. Spacetime curvature immediately follows - all masses must
fall identically in vacuum (pursue local parallel geodesic paths) -
and then GR. If we had two masses that did not fall identically, GR
would be falsified. Einstein would fall to more inclusive theory as
Euclid and Newton so succumbed.
Folks have looked real hard for two such test masses, starting with
Galileo some 412 years ago and now sensitive to one part in ten
trillion relative. 100% failure. There is only one examinable mass
property that has *never* been examined. It can be quantitatively
calculated from first principles. Paired test masses can be created
that are 99.9% divergent vs. overall rest mass.
http://www.mazepath.com/uncleal/eotvos.htm
Do something naughty to physics
http://www.mazepath.com/uncleal/eotvos.pdf
The short form
Somebody should look. Teh worst it can do is fail.
Edward Green
> In article <qIvp4D...@eisner.encompasserve.org>, bri...@encompasserve.org writes:
> > The vector sum of two velocities, v1 and v2 in a particular
> > reference frame is itself a vector. It is not, quite, a velocity,
> > but it is expresed in units of velocity. If the individual
> > vectors have values whose magnitudes are strictly less than c
> > then the vector sum will have a magnitude that is strictly
> > less than 2c.
> >
> > As I said, this sum is not the velocity of any particular object
> > in any particular reference frame. Instead, it is the time rate of
> > change in the (vector) separation between the two objects whose
> > velocities are v1 and v2 as viewed in the reference frame within
> > which those objects have those velocities.
>
> Damn. I accuse Uncle Al of a sign error and I make the exact same
> sign error myself.
"Signenerratum muss man nicht sich beitten an"
(We don't bother ourselves with sign errors)
Provide real German and attribute it to Planck or Einstein. :-)
> Take the _difference_ of those velocties, not their sum if you
> want the time rate of change in their vector separation.
Well, we know what we mean on that score.
I've been championing the idea recently "relative velocity" is a
physical object with certain transformation properties, whose
representation in a particular frame is v1 - v2, individual velocities
expressed in that frame. The correct rule to transform this object is
to transform v1, v2 to the new frame then form the difference again.
This rule includes the special case where we transform to a frame
where either v1, v2 = 0 -- the expected frame for "relativistic
velocity addition".
Ironically it is kind of unrelativistic in outlook to insist that a
physical object can only be represented in a certain frame of
reference -- why should "relative velocity" be any different?
Thanks for taking the time to inject a note of moderation.
me...@cars3.uchicago.edu
>
>I've been championing the idea recently "relative velocity" is a
>physical object with certain transformation properties, whose
>representation in a particular frame is v1 - v2, individual velocities
>expressed in that frame.
The name "relative velocity" is taken (as you well know). Use
"closing velocity" or "velocity of approach" for the above. We've
been over this before, as I'm sure you recall.
Mati Meron | "When you argue with a fool,
me...@cars.uchicago.edu | chances are he is doing just the same"
George Greene
: In <3DB81FA6...@hate.spam.net> Uncle Al <Uncl...@hate.spam.net> writes:
:
: [Three-clock version of the twin paradox]
:
: Hey, that's good. Really good!
Sure, the experiment is good, but the claim
that "nothing runs slow in any reference frame"
that preceded it was just hubristic hogwash.
Besides, the twin paradox is sort of mis-named.
In the 2-clock version, there is no paradox.
One clock runs slow, and it is the one that
got accelerated. The reason the twin paradox
was called a paradox is that if you IGNORE
acceleration, if you JUST look at relative
velocities, then the situation looks SYMMETRIC:
EACH twin thinks about the other that "he started
out where I am, he moved away from me at a high
speed for a while, and then moved back to me at
a similarly high rate of speed". If "moving clocks
run slow" were all there was to it, then each would
be expecting the other's clock to run slow.
THAT paradox (which IS a paradox) is resolved
only by noting that one of the clocks got
accelerated and the other didn't. You could actually
produce the same relative-velocity progression while
accelerating BOTH twins in opposite directions, but
if you did that, then when they got back together,
their clocks would agree; again, NO paradox.
In the 3-clock scenario, the first question is,
IS there any paradox to resolve??
As far as Al took it, he got to the point
where the sum of the numbers on the slips
excreted by clocks 2 and 3 was less than the
number on the slip excreted by clock 1,
but he DIDN'T SAY ANYTHING ABOUT what it looks
like from the viewpoint of the other 2 clocks.
The situation is almost symmetric (and symmetry is
NECESSARY BEFORE there can be any paradox to resolve)
in that all 3 clocks are turned on by a 1st encounter
with a 2nd clock and turned off by a subsequent encounter
with a 3rd clock. But if we compare the later off-
encounter to the earlier on-encounter, for all 3
clocks, the differences are as follows:
Clock 1 has its off-encounter with a clock arriving
at the same speed but from the opposite direction,
while clock 2 has its off-encounter
with a clock arriving at a higher speed from the
same direction, and clock 3 has its off-encounter
with a clock arriving a lower speed from the same
direction.
Is there a paradox here OR NOT?
George Greene
: Yes, but the difference is that in the three-clock case, no
: clock is physically accelerated. That should put an end to
: the idea that time dilation is something physical
: that happens to clocks when they accelerate.
No, it doesn't. You still haven't resolved the paradox.
If the situation is really symmetrical among the 3 clocks,
then you have paradox. As Uncle Al originally numbered it,
the sum of the times on the slips from clocks 2 and 3
was less than the time on the slip from clock 1.
But since all 3 clocks were started by their encounter
with a 2nd clock and stopped by their encounter with a 3rd
clock, his reasoning is going to lead to the conclusion
that there can exist positive rational numbers x,y, and z such that
x>y+z AND y>x+z AND z>x+y. This is obviously impossible.
How do YOU D.MC. break the symmetry?
: >Still, your prevarication has the valuable property of showing that it
: >is not any intrinsic effect of acceleration on the clock which results
: >in the "paradox", but only on the trajectory.
:
: Exactly. In Special Relativity, time dilation is a feature of
: spacetime, not a feature of clocks.
Time dilation is self-contradictory bullshit until you can
explain this paradox.
Richard
All quanta are involved in every interaction. No closed system exists
other than the universe itself.
>
> > Controlled fission,
> > hmmm Al, how the hell did that happen I wonder, I mean, radioactive
> > decay is independently spontaneous, uncaused, isn't it? Git.
>
> You don't need fission, controlled or otherwise, to make a clock based
> on radioactive decay.
You need radioactive decay, a physical event with physical causes.
What's your point?
> You are out of your depth and it shows.
Only your bared ignorance is showing.
The launching of a system into orbit introduces physical changes to the
system. Cyclic systems in particular are those under consideration, and
the magnitude of any effects on these will depend upon the actual
physical makeup of the system. Given forty different "types" of clocks
that were initially synchronized, "none" of those will be ticking at the
same rate after the ship that contains them assumes its final orbital
trajectory. Will you argue this point? If you think it incorrect then
please cite the evidence to the contrary, keeping in mind that a
pendulum clock will be one of those on board, and that a electric motor
driven clock will be another type. How will the change in gravitational
potential affect the pendulum, and how will the change in
electromagnetic potential affect the motor driven clock? Let another
clock be a vertically oscillating spring, how will the acceleration
affect the frequency of occultation? What type of clock can you imagine
that will not undergo physical changes when accelerated or when
relocated to a different gravitational and/or electromagnetic potential?
Go roll over on your back and piss on yourself like the well trained and
defeated dog that you are.
Richard
Richard
All quanta are involved in every interaction. No closed system exists
other than the universe itself.
>
> > Controlled fission,
> > hmmm Al, how the hell did that happen I wonder, I mean, radioactive
> > decay is independently spontaneous, uncaused, isn't it? Git.
>
> You don't need fission, controlled or otherwise, to make a clock based
> on radioactive decay.
You need radioactive decay, a physical event with physical causes.
What's your point?
> You are out of your depth and it shows.
Only your bared ignorance is showing.
The launching of a system into orbit introduces physical changes to the
system. Cyclic systems in particular are those under consideration, and
the magnitude of any effects on these will depend upon the actual
physical makeup of the system. Given forty different "types" of clocks
that were initially synchronized, "none" of those will be ticking at the
same rate after the ship that contains them assumes its final orbital
trajectory. Will you argue this point? If you think it incorrect then
please cite the evidence to the contrary, keeping in mind that a
pendulum clock will be one of those on board, and that a electric motor
driven clock will be another type. How will the change in gravitational
potential affect the pendulum, and how will the change in
electromagnetic potential affect the motor driven clock? Let another
clock be a vertically oscillating spring, how will the acceleration
affect the frequency of oscillation? What type of clock can you imagine
V.Gopal
> "V.Gopal" <vgop...@rediffmail.com> wrote in message
> news:38af3945.02102...@posting.google.com...
> > "Franz Heymann" <Franz....@btopenworld.com> wrote in message
> news:<apbp93$j5u$2...@knossos.btinternet.com>...
> > > "V.Gopal" <vgop...@rediffmail.com> wrote in message
> > > news:38af3945.02102...@posting.google.com...
> > > > In Special Relativity Theory the basis of "Twin Paradox" is that
> > > > "moving clocks run slow". What is not clear is that, when a 'clock
> > > > runs slow' whether its frequency continuously decreases or not.
> Can
> > > > anyone clarify this point?
> > >
> > > If a clock's frequency continuously decreases, it needs winding up.
> > >
> > > Franz Heymann
> > It needs no winding up, let it stop. What I want to know is how do we
> > express or convey continuously and uniformly decreasing rate of
> > counting. Can we know when we reach zero if the rate of counting
> > decreases uniformly and continuously?
> > Here 'counting' does not divide time into equal intervals and in this
> > case because there is no linear or angular displacement, time appears
> > to 'shrink' continuously. How can we canvey rate of shrinkage of time?
>
> I have not a clue as to what you might mean.
> I do have a strong suspicion that you don't know either.
>
> Franz Heymann
a speed of say, 100miles/hr and brake is applied to it. At the
enterence you stand and begin to count the number of compartments as
the train begins to decelerate. If the speed of the train was constant
the rate of counting of number of compartments would be uniform. That
is, the interval of time between any two consecutive numberes would be
same. When the train is decelerating the interval of time between 1
and 2 is less than that between 2 and 3 and so on. I call this as as
'continuous decrease in the rate of counting of numbers'. We cannot
see both the ends of a period of time. As long as the train is moving
counting is possible. When the speed approaches zero and becomes zero
there is no way to know at what point of time the train came to a rest
because, in L/T, L-->0 and T --->infinity. If we do not have the
decelerating object in front of us, there is no way to remember the
period of time that was spent without activity between two numbers. No
expression can convey decreasing rate of counting, which is same as
angular deceleration.
George Greene
: Nothing runs "slow" in any refernce frame. When otherwise identical
: clocks - one of which sustained a velocity relative to the other - are
: brought together to compare, one is seen to have less elapsed time
: than its twin due to its hyperbolic rotation through 4-space.
This is INCONSISTENT BULLSHIT, Al.
If one clock sustained a velocity relative to the other,
then THE OTHER SUSTAINED A VELOCITY RELATIVE TO THE ONE,
as well. Therefore, if the one is "seen to have less"
elapsed time than the other, the other MUST be "seen
to have less" elapsed time than the one.
SINCE THIS *CANNOT*HAPPEN* -- since you cannot exhibit
2 pieces of paper, each with a positive number on them,
where each number is less than the other, you are
not saying anything.
Hey, Daryl: you are not saying anything, either,
but you should.
Edward Green
> da...@cogentex.com (Daryl McCullough) writes:
> : Yes, but the difference is that in the three-clock case, no
> : clock is physically accelerated. That should put an end to
> : the idea that time dilation is something physical
> : that happens to clocks when they accelerate.
>
> No, it doesn't. You still haven't resolved the paradox.
> If the situation is really symmetrical among the 3 clocks,
> then you have paradox.
Well, it's not. Uncle VitriAl may be a foam flecked bile spewing
jackass painfully croaking obscenities from cracked and blackened lips
-- but he did not propose a thought experiment where the 3 clocks
enter symmetrically.
<...>
> Time dilation is self-contradictory bullshit until you can
> explain this paradox.
And your relation to unc.edu is what ... ? Oh, I see, you are in the
CS departement. Do you know James Hunter?
You probably wouldn't like it if I started ranting that a bubble sort
was self-contradictory bullshit, while simultaneously demonstrating a
lack of basic understanding of the bubble-sort algorithm, now would
you? I thought not.
Edward Green
> "Edward Green" <null...@aol.com> wrote:
> > Uncle Al <Uncl...@hate.spam.net> licked his crusted lips and spake:
> > > [snip incredible bulk of ignorant spew invalidated by common
> > > observation]
> >
> > Same to you, Al, you insulting sonofabitch. ...
> > Aha ... I see your idiocy. You are one of those people who are
> > completely blind to the frame dependence of "relative velocity".
> > Hell, not only are you blind to it, you even stated the concept in
> > equivalent words, and _still_ screwed it up. I quote from the
> > infallible master:
> >
> > "the sum of the velocities as viewed by any inertial observer"
> >
> > Bizarre. You suffer from the "relative velocity must be stated in
> > rest frame of one of two bodies" disease
>
> I look forward to reading how Uncle Al responds to that. {:-)
He won't. He may be given to spasms of free-form insult which give me
license to practice my best invective for the next 10 to 12 posts, or
until I cool off -- which ever comes later -- but I will give him
credit for realizing when he is in the wrong and at least
demonstrating the intelligence of a rock, and shutting up about it.
Better an apology, but at least not a negatively intelligent defense.
> Ed, there is no such concept in physics as a "relative velocity" in the
> abstract. The concept is restricted to such situations as "The velocity
> of A relative to B" or "The velocity of B relative to A". The former is
> a measurement made in the frame in which B is at rest. Vice versa for
> the latter.
Right. Well, I was expanding the concept "relative velocity" a tad
... though I didn't do this in the original post, so he doesn't have
that excuse.
But in the process of ranting about this, it occurs to me that we
_could_ think of "relative velocity" as a physical concept in the
abstract, one which has a frame dependent representation, like so many
other well loved physical concepts.
I pointed out in a reply to Briggs, though I don't mind repeating
myself ... well, let me change things a little. Let's call the
abstract physical object "skedaddle"; sk( , ); which has the following
properties: given two objects with velocities v1, v2 in an inertial
reference frame, then sk(1,2) has the representation v1 - v2 in that
frame. To obtain the representation in a different frame we are
required to first find v1', v2' in the new frame, by the usual
methods, then again form v1' - v2'.
"Skedaddle" reduces to "relative velocity" in the sense you and the
physics community seem to prefer when one of the two position holders
v1, v2 is zero in the given frame. On the other hand, in an arbitrary
frame, sk(1,2) is what I have suggested closing the "vector closure
rate", or one of some similar set of circumlocutions.
Now, I would think it is simpler just to call skedaddle "relative
velocity", or perhaps "relative vector velocity" consistently,
considered as an abstract frame independent object transforming
according to the stated rules: much like a vector. But I won't insist
on it -- what is important is that the concept be recognized as a
self-consistent and meaningful object, by whatever name.
But I hadn't even suggested this nomenclature when Al's brain lesion
acted up, so he will have to think of something more powerful than the
twinky defense, even if he hires Johnny Cochran.
> The situation under dicussion which leads to a maximum speed of 2c does
> *not* involve the velocity of anything relative to anything else. It is
> a "velocity of approach" of two objects *relative to me*, i.e. in the
> frame in which *I* am stationary.
Ok ... I won't argue strongly ... but I find it just as natural to
call this the "relative velocity in the frame in which I am
stationary". That is, in all cases the "relative velocity" has the
property that it is the vector derivative of D == X1 - X2, the
displacement, the "vector closure rate". In frames where I am
costationary with one of the bodies involved "vector closure rate"
maintains these general properties, while reducing to your "relative
velocity".
When the cocepts are well cemented we may go back to being sloppy.
> [...]
>
> > Relative velocity v1 - v2 is sensibly viewed as a physical object with
> > frame dependent representation
>
> You are simply privately redefining the concept of an approach velocity
> of two objects, as measured in the frame in which I am stationary. It
> is unnecessary.
Well, Ok ... I am certainly not entitled to redefine anything, but I
think the concept could use a name and is a useful concept, since this
confusion that anything which even _sounds_ like relative velocity
must be the canonical relative velocity is endemic. I've had to stop
and argue that the version not specifically represented in the rest
frame of one of the principals means _anything_ repeatedly.
And of course there is a certain sloppy sub-faction, typified for
today by Uncle VitriAl (I'm closing in on my quota) who want to do a
pattern recognition attack on "Doesn't get relativistic addition of
velocities ... nyah, nyah, nyah". Save it for Spaceman
(apostrophizing this rude faction)!
Assuming contrary to fact that Spaceman were an actual seeker after
knowledge and not the uncooperative troll we see in reality, the
"Doesn't get relativistic addition of velocities ... nyah, nyah, nyah"
reply is inadequate. An adequate reply acknowledges the extent that
the old "galilean" form of relative velocity really represents
something meaningful even within SR, before pointing out its modified
transformation properties as a physical object.
Nyah, nyah, nyah. Myanmar!
Proof that politically correct renomenization is silly.
Richard
Correct with the two exceptions:
1) It is based upon an empirical premise, namely that the order of
occurrence of events in the universe is frame invariant. To be more
precise, the universe itself, in its proceedings, doesn't take into
account our psychological exceptions to its behavior when executing its
"actual" laws. The universe carried on exceptionally well before man
ever introduced the concept of frames of reference, and will do so long
after man's frames of reference are gone.
The true principle of relativity is: The laws governing the behaviors of
matter are "independent" of frames of reference.
Invariance is just a mathematical method of providing that independence,
and SR fails miserably in that regard. The relative speed of two masses
is not Lorentz invariant, but it "is" Galilean invariant.
(v_x - v'_x) = (u_x' - u'_x'), which is to say the relative
instantaneous speed of two masses in frame K is precisely equal to the
relative speed of two masses in a frame K' moving wrt frame K. Inertial
frames are not required; K and K' can be frames in any sort of motion
wrt the masses, thus satisfying the mutual "independence" of events and
any frames of reference from which they are observed.
2) It needs to be amended to read ".....counting the cycles of a
repetitive process [in a virtually closed system].
Without this amendment the repetitive process ceases to be repetitive
wrt inertial frames. And although no process is precisely repetitive,
repetitiveness cannot even be approached if we allow systems that are
not in fairly constant ambient surroundings. Inertial frames are
introduced here because time is arbitrarily regarded as linear wrt
inertial motion (per the arbitrary definition F=ma). Accelerated clocks
would likewise serve equally well as standards so long as the correct
mathematical transformation to linear time were known, which would in
turn require taking into account variables that cannot be known without
reference to the linear passage of time, thus making the process rather
redundant right from the start, which is why it was omitted from the
original considerations.
Richard
Richard
Richard
Richard
Correct with the two exceptions:
Franz Heymann
Oracular words are of no interest when I asked for a response to a
question of physics.
Better luck next time
> > > Controlled fission,
> > > hmmm Al, how the hell did that happen I wonder, I mean,
radioactive
> > > decay is independently spontaneous, uncaused, isn't it? Git.
> >
> > You don't need fission, controlled or otherwise, to make a clock
based
> > on radioactive decay.
>
> You need radioactive decay, a physical event with physical causes.
> What's your point?
That you don't need fission, contrtolled or otherwise, to make a clock
based on radioactive decay. You raised it. Now read the reply.
>
> > You are out of your depth and it shows.
>
> Only your bared ignorance is showing.
>
> The launching of a system into orbit introduces physical changes to
the
> system. Cyclic systems in particular are those under consideration,
and
> the magnitude of any effects on these will depend upon the actual
> physical makeup of the system. Given forty different "types" of clocks
> that were initially synchronized, "none" of those will be ticking at
the
> same rate after the ship that contains them assumes its final orbital
> trajectory. Will you argue this point?
If they were clocks, and not some crude approximations to clocks, they
all by definition always count equal intervals of time. If they stay
together, they will then always indicate the same time lapse.
> If you think it incorrect then
> please cite the evidence to the contrary, keeping in mind that a
> pendulum clock will be one of those on board,
A pendulum is not a clock. Full stop. Its behaviour sepends on its
environment. This disqualifies it.
There is no need to read any further. I will however leave Richard's
nonsense as is for the delectation of other readers.
> and that a electric motor
> driven clock will be another type. How will the change in
gravitational
> potential affect the pendulum, and how will the change in
> electromagnetic potential affect the motor driven clock? Let another
> clock be a vertically oscillating spring, how will the acceleration
> affect the frequency of oscillation? What type of clock can you
imagine
> that will not undergo physical changes when accelerated or when
> relocated to a different gravitational and/or electromagnetic
potential?
None of the mechanisms you quoted qualify for clock candidates.
>
> Go roll over on your back and piss on yourself like the well trained
and
> defeated dog that you are.
Franz Heymann
Franz Heymann
Why are you so obseesd with time?
Why don't you also discuss the possibility that the length of your metre
stick changes, shrinking continuously?
Franz Heymann
Edward Green
> In article <2a0cceff.02102...@posting.google.com>, null...@aol.com (Edward Green) writes:
>
> >
> >I've been championing the idea recently "relative velocity" is a
> >physical object with certain transformation properties, whose
> >representation in a particular frame is v1 - v2, individual velocities
> >expressed in that frame.
>
> The name "relative velocity" is taken (as you well know). Use
> "closing velocity" or "velocity of approach" for the above. We've
> been over this before, as I'm sure you recall.
Yes. Ok ... I wasn't hoping so much to redefine it as to extend the
domain of definition. But you are right ... better call it something
else. I kind of like "skedaddle" or "scramola".
me...@cars3.uchicago.edu
>me...@cars3.uchicago.edu wrote in message news:<TNzu9.73$O4.1...@news.uchicago.edu>...
>>
>> >
>> >I've been championing the idea recently "relative velocity" is a
>> >physical object with certain transformation properties, whose
>> >representation in a particular frame is v1 - v2, individual velocities
>> >expressed in that frame.
>>
>> The name "relative velocity" is taken (as you well know). Use
>> "closing velocity" or "velocity of approach" for the above. We've
>> been over this before, as I'm sure you recall.
>
>domain of definition. But you are right ... better call it something
>else. I kind of like "skedaddle" or "scramola".
I vote for "skedaddle", it sounds neat.
Phil Holman
> "Franz Heymann" <Franz....@btopenworld.com> wrote in message
news:<apebil$lb8$6...@helle.btinternet.com>...
>
> > "Edward Green" <null...@aol.com> wrote:
>
> > > Uncle Al <Uncl...@hate.spam.net> licked his crusted lips and spake:
>
> > > > [snip incredible bulk of ignorant spew invalidated by common
> > > > observation]
> > >
> > > Same to you, Al, you insulting sonofabitch. ...
>
> > > Aha ... I see your idiocy. You are one of those people who are
> > > completely blind to the frame dependence of "relative velocity".
> > > Hell, not only are you blind to it, you even stated the concept in
> > > equivalent words, and _still_ screwed it up. I quote from the
> > > infallible master:
> > >
> > > "the sum of the velocities as viewed by any inertial observer"
> > >
> > > Bizarre. You suffer from the "relative velocity must be stated in
> > > rest frame of one of two bodies" disease
> >
> > I look forward to reading how Uncle Al responds to that. {:-)
>
> He won't. He may be given to spasms of free-form insult which give me
> license to practice my best invective for the next 10 to 12 posts, or
> until I cool off -- which ever comes later -- but I will give him
> credit for realizing when he is in the wrong and at least
> demonstrating the intelligence of a rock, and shutting up about it.
> Better an apology, but at least not a negatively intelligent defense.
Uncle Al's entertainment rating is sky high but the way he handle's himself
when suspecting a mistake (even if it's his own) with our more learned
posters unfortunately lacks class.
On a more amusing note......
Roll up, roll up
Uncle Al's Debunk Clinic here
You post em, we'll roast em
Never let a thesis beat us.
Phil Holman
Maleki
(Edward Green) wrote in
<2a0cceff.02102...@posting.google.com> that:
>I merely pointed out from your ambiguous sentence that the maximum
>speed difference between two arbitrary velocities is 2c in any
>inertial frame. That's c to the right of you and c to the left of
>you. Get it?
Hahahah :-))
-------------------------
az kalamAte naghze irAni:
khodAyA:
ghanA'at, sabr, va tahammol rA az mellatam bAzgir
va be man arzAnidAr.
"Ali Shari'ati"
Franz Heymann
The phrase "relative velocity" has been bagged for another purpose, so
you should dream up another name.
On second thoughts, don't do that. I think there is already a name for
what you are speaking about. Is it not "closure velocity"?
[...]
Franz Heymann
Franz Heymann
I forgot to recommend that you turn upside down the next pendulun you
encounter. Perhaps that will teach you something about perfectly
repetitive motion.
Franz Heymann
Franz Heymann
Balls. The order of events in the Universe is quite categorically not
frame invariant. You should bone up on SR.
You seem to be under the impression that a clock can be separated from
its frame.
> To be more
> precise, the universe itself, in its proceedings, doesn't take into
> account our psychological exceptions to its behavior when executing
its
> "actual" laws. The universe carried on exceptionally well before man
> ever introduced the concept of frames of reference, and will do so
long
> after man's frames of reference are gone.
>
> The true principle of relativity is: The laws governing the behaviors
of
> matter are "independent" of frames of reference.
>
> Invariance is just a mathematical method of providing that
independence,
> and SR fails miserably in that regard. The relative speed of two
masses
> is not Lorentz invariant, but it "is" Galilean invariant.
> (v_x - v'_x) = (u_x' - u'_x'), which is to say the relative
> instantaneous speed of two masses in frame K is precisely equal to the
> relative speed of two masses in a frame K' moving wrt frame K.
Inertial
> frames are not required; K and K' can be frames in any sort of motion
> wrt the masses, thus satisfying the mutual "independence" of events
and
> any frames of reference from which they are observed.
That would appear to have been a string of erroneous assertions.
>
> 2) It needs to be amended to read ".....counting the cycles of a
> repetitive process [in a virtually closed system].
I don't see the necessity for the addition. I see nothing wrong with
reading my wristwatch at the same time as radiating heat into the rest
of the universe
>
> Without this amendment the repetitive process ceases to be repetitive
> wrt inertial frames. And although no process is precisely repetitive,
> repetitiveness cannot even be approached if we allow systems that are
> not in fairly constant ambient surroundings. Inertial frames are
> introduced here because time is arbitrarily regarded as linear wrt
> inertial motion (per the arbitrary definition F=ma).
Huh?
> Accelerated clocks
> would likewise serve equally well as standards so long as the correct
> mathematical transformation to linear time were known, which would in
> turn require taking into account variables that cannot be known
without
> reference to the linear passage of time, thus making the process
rather
> redundant right from the start, which is why it was omitted from the
> original considerations.
Franz Heymann
Maleki
<Uncl...@hate.spam.net> wrote in
<3DBAB45D...@hate.spam.net> that:
> Paired test masses can be created
>that are 99.9% divergent vs. overall rest mass.
What do you mean by "divergent"?
-------------------------
az kalamAte naghze irAni:
khodAyA:
roshde elmi va aghliye marA az fazilate "ta'assob"
va "ehsAs" va "eshrAgh" mahrum nasAz.
"Ali Shari'ati"
V.Gopal
stick does shrink or elongate depending on the environment. No
experiment within the four walls of a laboratory can prove that
'dimension' of unit of time can be changed by changing the
environment. If both length and time are assigned similar properties
then mass includes the clock that 'runs slow'. We have every reason to
believe that the problem of calculating the internal change is shifted
to the clock. According to Newton's law, a force of constant magnitude
'works' with continuously increasing power. Has this possibility been
proved in a laboratory?
James Hunter
"V.Gopal" <vgop...@rediffmail.com> wrote in message
news:38af3945.02102...@posting.google.com...
> "Franz Heymann" <Franz....@btopenworld.com> wrote in message
news:<aph1bg$1fq$6...@sparta.btinternet.com>...
> > "V.Gopal" <vgop...@rediffmail.com> wrote in message
> >
> >
> > Franz Heymann
> Length does shrink or elongate during acceleration. 'Length' of metre
> stick does shrink or elongate depending on the environment. No
> experiment within the four walls of a laboratory can prove that
> 'dimension' of unit of time can be changed by changing the
> environment. If both length and time are assigned similar properties
> then mass includes the clock that 'runs slow'. We have every reason to
> believe that the problem of calculating the internal change is shifted
> to the clock. According to Newton's law, a force of constant magnitude
> 'works' with continuously increasing power. Has this possibility been
> proved in a laboratory?
If the thin plate skulls of hallucinating neo-caveman chemists can prove
that time cannot be changed, then four walls easily prove that it can be
changed.
Richard
Let event1 be the ejection of an electron from a negative test charge,
and let event2 be the absorption of that electron by a positive test
charge. From what frame of reference is the electron ejected from the
positive test charge and absorbed by the negative test charge, and what
law governs this interaction? Is causation to be sidelined, and if so
then how is the event still predictable? Do you see the inherent
contradiction here Franz? You really haven't thought this out very
well, have you? The observed time of an event is not the actual time of
occurrence of that event, and one of these days you'll understand that
this is all that the Lorentz transform says. It assigns infinite
propagational velocity to light, and assigns time dilation and length
contraction as the causes of propagational delay (required because light
is no longer something that propagates, but is rather regarded as an
instantaneous connection between charges). It is a mathematical twist
that was completely out of order, uncalled for, and most especially just
plain stooopid.
>
> You seem to be under the impression that a clock can be separated from
> its frame.
I've thrown an alarm clock or two, a clear example of separation of a
clock and "my" frame. Had it been nailed to the table, then it would
have been me that accelerated, but I would have still used the clock as
a reference timepiece to measure my velocity toward the opposite wall. A
standard needs to remain in a constant state in order to remain a valid
standard, unless any physical effects on it are predictable to the point
of allowing a precise conversion of its measured readings to proper time
(the standard). A particular clock must be adopted as a standard for use
by observers in all frames when performing a series of directly related
calculations, just as a particular dictionary must be chosen as a
standard reference in order to formulate intelligent conversation. Terms
have to be well defined.
You know what they say about opinions. You know the premise is correct,
physical interactions occur entirely independently of how they are
perceived. Changing frames of reference will not change the course of
events, only the perception of them.
>
> >
> > 2) It needs to be amended to read ".....counting the cycles of a
> > repetitive process [in a virtually closed system].
>
> I don't see the necessity for the addition. I see nothing wrong with
> reading my wristwatch at the same time as radiating heat into the rest
> of the universe
As long as you don't change in temperature this isn't a problem, but
when the clock warms up it ain't gonna tick the same anymore Franz.
> >
> > Without this amendment the repetitive process ceases to be repetitive
> > wrt inertial frames. And although no process is precisely repetitive,
> > repetitiveness cannot even be approached if we allow systems that are
> > not in fairly constant ambient surroundings. Inertial frames are
> > introduced here because time is arbitrarily regarded as linear wrt
> > inertial motion (per the arbitrary definition F=ma).
>
> Huh?
Time is linear wrt the law of inertia as it is defined. If we define
time as nonlinear wrt a uniformly moving body then it will then be
accelerating "on paper". The choice is arbitrary, I'm surprised that you
don't understand that scales can be arbitrarily manipulated. As long as
all other scales are altered to reflect the change in one, the logical
system remains consistent. You really don't get this? LOL:-)
>
> > Accelerated clocks
> > would likewise serve equally well as standards so long as the correct
> > mathematical transformation to linear time were known, which would in
> > turn require taking into account variables that cannot be known
> without
> > reference to the linear passage of time, thus making the process
> rather
> > redundant right from the start, which is why it was omitted from the
> > original considerations.
>
> Franz Heymann
Richard
Franz Heymann
I asked you to bone up on SR before answering. The above nonsense shows
that you have not.
> >
> > You seem to be under the impression that a clock can be separated
from
> > its frame.
>
> I've thrown an alarm clock or two, a clear example of separation of a
> clock and "my" frame.
Please read what I said.
The rest will obviously not be worth reading, so I will not.
Franz Heymann
Franz Heymann
You were talking about a continuing, enduring rate of change, unless I
misunderstood you.
> No
> experiment within the four walls of a laboratory can prove that
> 'dimension' of unit of time can be changed by changing the
> environment. If both length and time are assigned similar properties
> then mass includes the clock that 'runs slow'.
A clock is what measures time. The concept of a clock running slow in
its own frame is nonsense, unless you bought a bum clock.
> We have every reason to
> believe that the problem of calculating the internal change is shifted
> to the clock.
Sorry, I cannot understand what you mean.
> According to Newton's law, a force of constant magnitude
> 'works' with continuously increasing power.
That is gobbledegook.
> Has this possibility been
> proved in a laboratory?
The laboratory and gobbledegook don't mix well.
Gopal, you talk so much nonsense that I would rather not continue the
discussion.
Franz Heymann
Edward Green
> The phrase "relative velocity" has been bagged for another purpose, so
> you should dream up another name.
> On second thoughts, don't do that. I think there is already a name for
> what you are speaking about. Is it not "closure velocity"?
Right. Mati made same objection. Closure velocity it is. Though I
still like "skedaddle", and someday hope to find a use for "scramola".
E.g. "Two photons emitted in opposite directions in the lab frame
have a skedaddle of 2c".
Also could use impressive name for closure velocity in terms of its
transformation properties; not quite a vector, but has definite
transfomation laws. "Closure velocity is a bi-axial pseudo-vector",
or whatever, would make it sound like a real citizen.
Relative velocity is closure velocity in the rest frame of one of the
particles.
jmfb...@aol.com
me...@cars3.uchicago.edu wrote:
>In article <2a0cceff.0210...@posting.google.com>,
null...@aol.com (Edward Green) writes:
>>me...@cars3.uchicago.edu wrote in message
news:<TNzu9.73$O4.1...@news.uchicago.edu>...
>>> In article <2a0cceff.02102...@posting.google.com>,
null...@aol.com (Edward Green) writes:
>>>
>>> >
>>> >I've been championing the idea recently "relative velocity" is a
>>> >physical object with certain transformation properties, whose
>>> >representation in a particular frame is v1 - v2, individual velocities
>>> >expressed in that frame.
>>>
>>> The name "relative velocity" is taken (as you well know). Use
>>> "closing velocity" or "velocity of approach" for the above. We've
>>> been over this before, as I'm sure you recall.
>>
>>Yes. Ok ... I wasn't hoping so much to redefine it as to extend the
>>domain of definition. But you are right ... better call it something
>>else. I kind of like "skedaddle" or "scramola".
>
>I vote for "skedaddle", it sounds neat.
And, if the experiment goes wrong, the scientists execute a
scramola.
/BAH
Subtract a hundred and four for e-mail.
me...@cars3.uchicago.edu
>In article <lAWu9.4$P4....@news.uchicago.edu>,
> me...@cars3.uchicago.edu wrote:
>null...@aol.com (Edward Green) writes:
>>>me...@cars3.uchicago.edu wrote in message
>news:<TNzu9.73$O4.1...@news.uchicago.edu>...
>>>> In article <2a0cceff.02102...@posting.google.com>,
>null...@aol.com (Edward Green) writes:
>>>>
>>>> >
>>>> >I've been championing the idea recently "relative velocity" is a
>>>> >physical object with certain transformation properties, whose
>>>> >representation in a particular frame is v1 - v2, individual velocities
>>>> >expressed in that frame.
>>>>
>>>> The name "relative velocity" is taken (as you well know). Use
>>>> "closing velocity" or "velocity of approach" for the above. We've
>>>> been over this before, as I'm sure you recall.
>>>
>>>Yes. Ok ... I wasn't hoping so much to redefine it as to extend the
>>>domain of definition. But you are right ... better call it something
>>>else. I kind of like "skedaddle" or "scramola".
>>
>>I vote for "skedaddle", it sounds neat.
>
>scramola.
>
Shmuel (Seymour J.) Metz
In <2a0cceff.02102...@posting.google.com>, on 10/25/2002
at 06:40 AM, null...@aol.com (Edward Green) said:
>I doubt this. I've seen you make this claim before.
It's standard kinematics in a Minkowski space-time. It's also well
supported by experimental data.
>What? Given any "achievable velocities" v1 and v2, the sum is
>bounded by 2c. Since the frame in which the sum is 2c - eps is an
>inertial frame, that is your bound: v1 + v2 < 2c.
The issue isn't the sum, the issue is the speed of one frame as
measured in the other. If v1 < c and v2 < c then that speed is bounded
by c, not just by 2c.
>Oh ... you cheated! You used _three_ clocks.
But he didn't cheat enough. Had he used 4 clocks, he could have made
it clear that the paradox is symmetrical.
><Sententious conclusion mode>: Indeed, how could it be otherwise? SR
>knows nothing of acceleration,
Really? Then what is &x^i/&s along a worldline, where s is the
interval? It sure looks like acceleration to me.
>hence any effects of acceleration in SR must merely be an integrated
>compounding of many small increments of constant velocity.
What is the trajectory of a charged point-mass in an E-M field? Hint:
it doesn't have small increments of constant velocity.
>To deal
>with the effects of acceleration per se on matter we need GR.
No. We need GR to deal with accelerated frames of reference, not to
deal with acceleration of matter in an inertial frame.
--
Shmuel (Seymour J.) Metz, SysProg and JOAT
Atid/2, Team OS/2, Team PL/I
Any unsolicited commercial junk E-mail will be subject to legal
action. I reserve the right to publicly post or ridicule any
abusive E-mail.
I mangled my E-mail address to foil automated spammers; reply to
domain Patriot dot net user shmuel+news to contact me. Do not
reply to spam...@library.lspace.org
Daryl McCullough
>My path is something like this
>
>(1) mythical prehistory -- need GR to handle accelerated bodies
>
> (I don't think I ever actually believed this)
>
>(2) pre-current state -- acceleration in SR can be handled by a
>combination of integration (effect of a sequence of instantaneous rest
>frames) plus material effects (stress, etc).
>
>(3) glimmer of nuance --
>
>I have a momentary doubt that both of these programs correctly applied
>are sufficient to completely exhaust any "GR effects" of accelerated
>object in flat spacetime.
Okay, you are certainly allowed doubts. But your previous understanding,
number (2) is correct.
>Let's look at our friend the Ehrenfest disk again. We proceed in flat
>space in an inertial frame of reference, and consider a disk spinning
>at steady state, which has already resolved all its inner length
>contraction/stress/transient issues.
>
>Now, on the theme of "kinematics still works as before in fixed
>inertial frame", all points at radius r from the axis have
>instantaneous speed u = rw, and instantaneous acceleration a = rw^2.
>Ok. Now, suppose we choose to fix u, while allowing r to shrink and w
>to increase. We see that while u remains fixed, a will scale with
>omega.
>
>Now, lets consider the effect on clocks at this radius. First, during
>any small time interval dt in the inertial frame, the clocks are
>moving with a given u, hence should appear to be running slower
>"special relativistically".
>
>Agree?
So far.
>Second, because of the increasing acceleration, the stress on the
>clocks will increase, which may affect their time keeping ability
>purely "mechanically". I.e. (hold your fire, Daryl), they may undergo
>physical effects which we would not refer to as "time dilation", but
>nonetheless affect the rate at which the clocks run compared to a
>unstressed reference.
>
>Agree?
Yes, that's certainly a possibility. However to actually calculate
such an effect, you have to know what kind of clock you're talking
about. I don't think there would be any *universal* effect of that
type; any effect of acceleration will depend on the type of clock,
what it's made of, how big it is, etc.
I think that if we use say radioactive decay as our clock, then
the effects of acceleration will be negligible, unless we're talking
about really, really, big accelerations.
>So, we have possibly mechanically affected clocks further running at
>an apparently aberrant rate, even accounting for the mechanical
>effects, via Lorentz transformation.
>
>I hope you agree so far.
Okay.
>Now, according to the programme "SR contains all effects of
>acceleration in flat spacetime", we are apparently finished. There
>are no more possible physical effects on the clocks, and hence, first
>correcting for mechanical effects of acceleration, we predict any
>further disagreement with clocks at rest in the inertial frame
>according to the Lorentz transformation.
>
>Now, have we exhausted the possible effects of acceleration on clocks,
>or not? You would claim that we have,
Yes.
>and I hope I have at least
>stated your programme fairly and convincingly. I am however not 100%
>convinced we have exhausted the physical description. Here's why.
>
>First, back to pure SR a moment. I claim, though I have not struggled
>with this in a while, that _most_ of the effects of SR can be
>predicted macroscopically by analyzing the behavior of a flotilla of
>space ships which keep themselves in formation by exchanging timed
>radar pulses.
Sort of. What you mean is something like this: each spaceship sends
light signals to its neighbors, and receives replies. The spaceships
then adjust their positions so that the replies from neighbors on
either side arrive at the same time. Is that right?
>In a fixed inertial frame, the observer sees the
>flotilla is making "mistakes" by ignoring the differing forward,
>backward and lateral propogation of light in their own rest frame.
>_We_ see the effects of their relative motion past us, but they
>blithly ignore it.
>
>Almost, but not quite "explain" SR, I think.
I think that something like that can be used to justify
the Lorentz transformations. However, you need to make
physical assumptions about the laws governing motion and
forces in order to get that they have the same form in
all inertial frames.
>The catch is, in order
>to make this picture consistent, we have to reach inside systems on
>the ships we have not analyzed, and _postulate_ their adherence to SR.
> And I believe, if we then analyzed these smaller systems, we would
>find yet smaller systems within 'em which we again had to resort to
>postulation on. So we seem to be onto something, but we can't quite
>close the loop, and ultimate must adopt the Lorentz invariance of
>physics as a postulate, maddeningly hinted at by a kind of infinite
>recursion.
>
>Ok.
Maybe I agree.
>Now, I'm thinking of your nice analysis of gravitational redshift in
>terms of the bow and stern of an accelerating space ship, and doppler
>effects. Here is a case where we get the gravitational/accelerational
>equivalence effects of GR for free from SR. This would tend to
>substantiate your claim that all we need is SR to analyze any possible
>effect of acceleration in flat space time. But I'm also thinking
>about this infinite recursion thing ...
>
>Proposed moral: there may be acceleration effects on matter, beyond
>those predicted macroscopically by a close application of SR to
>analyzing the components (like the space ship doppler red shit), and
>beyond continuum mechanistic constituent relation effects ... like
>stress strain, etc.
Okay, there are two meanings of "there may be acceleration effects...".
Do you mean that General Relativity may describe such effects? Or do
you mean that there may be such effects that are not captured by
General Relativity? The latter is certainly a possibility, and I
think it can only be checked by experiment. The former (asking whether
GR predicts such things) is a pure mathematical question, and I'm
pretty sure that the answer is "no".
>These might correspond to something like "stresses and strain in the
>nuclei", below our level of analysis with SR, which would in fact need
>the machinery of GR to tease out, albeit we remained in flat
>gravitation free space.
No. If you mean additional acceleration-dependent effects predicted
by GR, then the answer is no. As I said before, GR is mathematically
equivalent to SR in the case of flat spacetime. If spacetime is
flat, then GR is nothing more than SR rewritten in coordinate-independent
language.
>> No. There is no purely GR-ish effect in flat spacetime.
>
>Maybe. I only claim, via above analysis, that my doubt is
>not-so-stupid, though it may appear tautological that SR is GR in flat
>spacetime, so there is nothing more to say. We may lose something in
>the simpler machinery.
As I say, it may be that there are acceleration-dependent effects
not accounted for by SR---but such effects won't be accounted for
by GR, either. It's also possible that for practical reasons the
machinery of GR is needed to solve some hairy problem. But the
machinery of GR is just the mathematics of curvilinear coordinate
systems. I think we can distinguish the theory from the tools
necessary to work with the theory. The theory doesn't change
just because the problems get harder.
>Consider an Ehrenfest disk again, now masquerading as a centrifuge,
>and consider the clocks at r, again. Are you certain we will have
>exhausted any effects on these clocks tending to upset their
>synchronization with inertial clocks by first considering their speed,
>next an mechanical effects of the centrifugal acceleration?
>
>If we have, then what has happened to the equivalence principle?
The equivalence principle is essentially the claim that any
problem in GR with a fixed spacetime metric can be solved by
using SR locally.
>These clocks appear to be at the bottom of a gravity well equivalent
>wrt a clock on the hub,
What you seem to want to do is to convert the acceleration problem into
a gravity problem, and then use GR to solve it. But how do you think
that GR solves such problems? It solves them by switching to a free-falling
coordinate system and then applying SR. So, using GR can't possibly
give you anything new.
>but I don't see any possibility for an
>equivalent effect ... we don't have Doppler any more to appeal to,
>unless some kind of relativistic transverse Doppler effect?
You don't need Doppler effect for this problem. Clocks that
are "higher" in the effective gravitational field are the
ones that are closer to the center of the centrifuge. Thus,
those clocks are moving slower (since velocity is proportional
to the distance from the center). Thus, they will experience
less time dilation. So a sort of "gravitational" time-dilation
is observed when you compare clocks higher and lower in the
effective gravitational field. Work out the numbers, and you
will find that the shift is exactly what is predicted by the
equivalence principle.
It is kind of strange that the same effect (gravitational
time dilation) is sometimes explained by time dilation, and
sometimes explained by Doppler shift. But the net effect is
the same: clocks lower in a "gravitational field" appear to
run slower.
--
Daryl McCullough
Ithaca, NY
Franz Heymann
"Shmuel (Seymour J.) Metz" <spam...@library.lspace.org.invalid> wrote
in message news:3dbd4891$1$fuzhry+tra$mr2...@news.patriot.net...
[...]
> Really? Then what is &x^i/&s along a worldline, where s is the
> interval? It sure looks like acceleration to me.
To me it looks like a component of the four-velocity, unless I am
misunderstanding your nomenclature.
[...]
Franz Heymann
Edward Green
> In <2a0cceff.02102...@posting.google.com>, on 10/25/2002
> at 06:40 AM, null...@aol.com (Edward Green) said:
>
> >I doubt this. I've seen you make this claim before.
>
> It's standard kinematics in a Minkowski space-time. It's also well
> supported by experimental data.
For a computer guy you seem kind of light on Usenet etiquette.
Rule #1 in Usenet replies: Don't snip so much context the reader has
no idea what you are replying to. You may notice that it's been
several days since I posted that. You're very flattering, but I don't
think many people are given to memorizing my stuff ... including me.
Who the hell knows what "this" is now?
Rule #1b: Make sure _you_ understand the context before replying.
By "it" you seem to understand the twin paradox in general. By "this"
it would have been evident from context that I understood the claim
that the twin paradox can be executed without any accelerated clocks.
In reference to what you thought you were replying to: I have no
problem with SR per se and the twin paradox in particular, but I would
like to know of any specific experimental test of the twin paradox, as
opposed to the structure of SR which supports it. How is the twin
paradox _per se_ "well supported by
experimental data" -- references.
> >Oh ... you cheated! You used _three_ clocks.
>
> But he didn't cheat enough. Had he used 4 clocks, he could have made
> it clear that the paradox is symmetrical.
No, no, no. The paradox is _not_ symmetrical -- at least by any
meaning I understand by "symmetrical". Uncle VitriAl is a horse's
ass, but in this case he happens to be a _correct_ horse's ass -- a
version of the twin paradox is constructed wherein the difference in
proper time along two spacetime trajectories between two events is
expected to be observed, but no clock is accelerated.
What Al shows is that the physical effects of acceleration on the
clock are irrelevant -- however, the acceleration of one _trajectory_
is indeed relevant, and breaks the symmetry.
> ><Sententious conclusion mode>: Indeed, how could it be otherwise? SR
> >knows nothing of acceleration,
>
> Really? Then what is &x^i/&s along a worldline, where s is the
> interval? It sure looks like acceleration to me.
Looks more like velocity to me, but let's not split hairs.
What I meant is that acceleration does not explicitly enter as a term
in the Lorentz transformations. This means that an "effect" of
acceleration in SR will be the effect of an integration of
differential increments with constant velocity. This is what Al's
version captures, while excluding a direct "acceleration effect" on
the clocks.
Al's version forces us to make the logical distinction between
physical acceleration of a clock, and acceleration in the world line
-- which in this case is all concentrated in one kink. Al, as is
common with brilliant but erractic people -- particularly those
possibly suffering from undiagnosed brain lesions -- concocted a
brilliant example, but failed to fully analyze its significane: his
example splits acceleration of material bodies from acceleration of
the trajectory.
> >hence any effects of acceleration in SR must merely be an integrated
> >compounding of many small increments of constant velocity.
>
> What is the trajectory of a charged point-mass in an E-M field? Hint:
> it doesn't have small increments of constant velocity.
Um... have you studied calculus? It would seem not. And don't tell
me I didn't say "infinitesimal" -- it would be obvious to a person of
ordinary skill in the art what I was getting at. You are not trying
out for advanced horse's ass placement, are you?
> >To deal
> >with the effects of acceleration per se on matter we need GR.
>
> No. We need GR to deal with accelerated frames of reference, not to
> deal with acceleration of matter in an inertial frame.
You are right on this one. I knew that -- I claim -- but that's not
what I wrote, so fair is fair. In retrospect I'm wondering if there
may not be some more subtle effects of acceleration captured by the
machinery of GR, which are lost in translation to SR.
Maybe I am wrong, but at least I'm wrong in a subtle way. ;-)
> >What? Given any "achievable velocities" v1 and v2, the sum is
> >bounded by 2c. Since the frame in which the sum is 2c - eps is an
> >inertial frame, that is your bound: v1 + v2 < 2c.
>
> The issue isn't the sum, the issue is the speed of one frame as
> measured in the other. If v1 < c and v2 < c then that speed is bounded
> by c, not just by 2c.
Nope ... the "issue" here is the sum, because what Al wrote is "the
sum". The sum is the sum is the sum ... even in SR. I suppose, if
you like, you could say the "relativistic sum". The "relativistic
sum" of two velocities is bounded by c, the sum of two velocities is
bounded by 2c.
> Shmuel (Seymour J.) Metz, SysProg and JOAT
> Atid/2, Team OS/2, Team PL/I
Very impressive, for a programmer. Unfortunately the subject is
physics, for which you bat about 1 for 5 on your criticisms. However,
you are at least head and shoulders above fellow CS guy George Greene,
who dismisses SR as "self-contradictory bullshit". He's probably a
crummy programmer too.
Imagine what a reception I would get if I started posting in groups
frequented by all your kewl programming friends, jumped in in the
middle of a thread and began criticizing without paying attention to
context or what was actually written. Consider that I have been
polite under the circumstances.
Shmuel (Seymour J.) Metz
at 03:26 PM, null...@aol.com (Edward Green) said:
>No, no, no. The paradox is _not_ symmetrical -- at least by any
>meaning I understand by "symmetrical".
I can't help the fact that you don't understand simple terms. With 4
clocks and point-of-contact signalling, each observer sees that his
measured time is greater than the measured time on a broken
trajectory. Thus each observer perceives his clock as running faster
than the other's. That's symmetrical.
>What Al shows is that the physical effects of acceleration on the
>clock are irrelevant -- however, the acceleration of one
>_trajectory_ is indeed relevant, and breaks the symmetry.
No; his thought experiment is intrinsically asymmetrical. Adding a
fourth clock restores the symmetry.
>Looks more like velocity to me, but let's not split hairs.
Sorry; typo. I meant &^2xî/&s or &v^i/&s, where s is interval.
>What I meant is that acceleration does not explicitly enter as a
>term in the Lorentz transformations.
That's certainly true.
>Um... have you studied calculus?
Better than you, it would seem
>And don't tell me I didn't say "infinitesimal"
Why would I tell you that? I'd be more likely to tell you that you
don't understand the difference between an integral and a sum.
>-- it would be obvious to a person of
>ordinary skill in the art what I was getting at.
Yes, it would be obvious that you don't understand the concept of a
limit. Maybe you should have taken a real Calculus class instead of
Calculus for Engineers.
>You are not trying
>out for advanced horse's ass placement, are you?
No; I'd stand no chance as long as you were in the running.
>Very impressive, for a programmer. Unfortunately the subject is
>physics,
Then stop posting it to sci.math, where you are batting 0 for 5. You
might also stop posting to sci.logic, which is even less relevant. For
a while I thought that you were AP.
--
Shmuel (Seymour J.) Metz, SysProg and JOAT
Atid/2, Team OS/2, Team PL/I
Any unsolicited commercial junk E-mail will be subject to legal
Franz Heymann
[...]
How is the twin
> paradox _per se_ "well supported by
> experimental data" -- references.
You generate many slowly moving pion in the lab. You measure their mean
lifetime in the lab
You generate many fast mesons moving like bats out of hell in the same
lab. I have done this with pions having gamma factors of up to 700.
You measure their mean lifetime in the lab. The second figure is gamma
times larger than the first.
Franz Heymann
Edward Green
I don't doubt that. I was careful to distinguish between experiments
which supported the structure of SR in general, from which we deduce
the expected behavior of the twins, to experiments which could be
mapped directly to the twin paradox. The reason I made this
distinction is that the poster I replied to was blithly claiming "it"
was "well supported by experimental data" -- it being, in context, the
twin paradox. I modestly ask how the twin paradox per se has been
subject to direct experimental test.
Your example is to the point, close by, small impact parameter, near
kill zone, as it deals with relativistic time dilation. Nonetheless
it is not a direct experimental test of the twin paradox set-up, and
if one is going to support the sentence "it <antecendent -- the twin
paradox> ... well attested ... experimental" ... then I think if one
is not talking through one's hat one should have up one's sleeve or
possibly secreted in one's trouser legs direct experimental tests of
the twin paradox per se, and not its second cousin.
I am especially peeved -- an easy state for me -- because the PP
(prior poster) executed a double regression to what he wanted to
argue, vs. addressing what I was actually saying -- first, from what
in context was clearly Al's specific claim that he could do it without
accelerated clock, to any old twin paradox in general, second, from my
(alleged) doubt of the any old twin paradox in general, to an implied
doubt of relativity in general.
Beauty, huh? I doubt (1) Al's claim he can do twin paradox without
acclerated clocks, hence (?) (2) I doubt analysis of twin paradox in
general, hence (??) I doubt relativity in general. This is the state
the PP wants to achieve, because then he can make vague authoritative
pronouncements about "well attested by experiment".
Nothing anybody from the PP to Uncle VitriAl to, yes, e'en you
occasionally, likes so much as good SR denier, so one can cite
authoritative sounding experiemental evidence. Much simpler than
trying to figure out exactly what I was getting at, isn't it.
Franz Heymann
"Shmuel (Seymour J.) Metz" <spam...@library.lspace.org.invalid> wrote
> In <2a0cceff.02102...@posting.google.com>, on 10/28/2002
> at 03:26 PM, null...@aol.com (Edward Green) said:
[...]
> >Looks more like velocity to me, but let's not split hairs.
>
> Sorry; typo. I meant &^2xî/&s or &v^i/&s, where s is interval.
How about fixing your latest typo? Or don't you know any better?
Franz Heymann
Franz Heymann
This is a direct test of the twins paradox, your objections
notwithstanding. Both classes of muon are born and die in the lab. The
ones which moved were older when they died..
If you must have an apparently more direct test, there are the clocks
flown in aircraft, compared before take-off and landing with an
earthbound clock.
That type of experiment was later repeated with greater accuracy by
comparing an earthbound clock with one flown in a low orbit spacecraft.
>
> I am especially peeved -- an easy state for me -- because the PP
> (prior poster) executed a double regression to what he wanted to
> argue, vs. addressing what I was actually saying -- first, from what
> in context was clearly Al's specific claim that he could do it without
> accelerated clock, to any old twin paradox in general, second, from my
> (alleged) doubt of the any old twin paradox in general, to an implied
> doubt of relativity in general.
>
> Beauty, huh? I doubt (1) Al's claim he can do twin paradox without
> acclerated clocks, hence (?) (2) I doubt analysis of twin paradox in
> general, hence (??) I doubt relativity in general. This is the state
> the PP wants to achieve, because then he can make vague authoritative
> pronouncements about "well attested by experiment".
>
> Nothing anybody from the PP to Uncle VitriAl to, yes, e'en you
> occasionally, likes so much as good SR denier, so one can cite
> authoritative sounding experiemental evidence. Much simpler than
> trying to figure out exactly what I was getting at, isn't it.
Well, instead of letting us flounder trying to figure what you were
getting at, just tell us.
Franz Heymann
Shmuel (Seymour J.) Metz
at 09:01 PM, "Franz Heymann" <Franz....@btopenworld.com> said:
>> Sorry; typo. I meant &^2xŻ/&s or &v^i/&s, where s is interval.
>How about fixing your latest typo? Or don't you know any better?
It's not as large a typo as you believe; it looks worse because your
news client is ignoring the Content-Type: text/plain;
charset=ISO-8859-1 in my article. The difference between what I typed
and what I meant to type is one space character. You're so brilliant,
you should be able to figure out what happened.
Franz Heymann
"Shmuel (Seymour J.) Metz" <spam...@library.lspace.org.invalid> wrote
> In <apphal$4me$8...@helle.btinternet.com>, on 10/30/2002
> at 09:01 PM, "Franz Heymann" <Franz....@btopenworld.com> said:
>
>
> >How about fixing your latest typo? Or don't you know any better?
>
> It's not as large a typo as you believe; it looks worse because your
> news client is ignoring the Content-Type: text/plain;
> charset=ISO-8859-1 in my article. The difference between what I typed
> and what I meant to type is one space character. You're so brilliant,
> you should be able to figure out what happened.
I am not vey brilliant. I cannot figure out what happened. All I know
is that in your latest line of maths up above here, there are two errors
which I hope
are only typos.
Franz Heymann
Edward Green
> "Shmuel (Seymour J.) Metz" <spam...@library.lspace.org.invalid> wrote
> in message news:3dc13d76$3$fuzhry+tra$mr2...@news.patriot.net...
> > In <apphal$4me$8...@helle.btinternet.com>, on 10/30/2002
> > at 09:01 PM, "Franz Heymann" <Franz....@btopenworld.com> said:
> >
> > >> Sorry; typo. I meant &^2x¯/&s or &v^i/&s, where s is interval.
>
> > >How about fixing your latest typo? Or don't you know any better?
> >
> > It's not as large a typo as you believe; it looks worse because your
> > news client is ignoring the Content-Type: text/plain;
> > charset=ISO-8859-1 in my article.
So that's how it's done. Huh. I was aware empirically that sometimes
special characters appeared as gobbledegook, sometimes as special
characters.
But you know what? Given the wide variety of newsreaders out there,
including those which ignore such frippery, it's best just to use the
ascii God gave us (either as an afterthought while having his coffee
on the seventh day, or on the tablets).
Please add this to the Usenet etiquette list I started for you.
> > The difference between what I typed
> > and what I meant to type is one space character. You're so brilliant,
> > you should be able to figure out what happened.
>
> I am not vey brilliant. I cannot figure out what happened. All I know
> is that in your latest line of maths up above here, there are two errors
> which I hope
> are only typos.
Yes. Well, the tyro has wandered in from some computer group, armed
to the teeth with credentials, and expects the same mores to apply --
you didn't realize it was in character set ISO-8859-1 !!??? (Gales of
laughter from gallery).
As I said, I am only faithfully reproducing what would happen if I
wandered into his homeland and began preaching about assembly code --
toned down by about two orders of magnitude.
Edward Green
> "Edward Green" <null...@aol.com> wrote in message
> news:2a0cceff.02103...@posting.google.com...
> > "Franz Heymann" <Franz....@btopenworld.com> wrote in message
> news:<apn5i7$1rs$1...@knossos.btinternet.com>...
> > > You generate many slowly moving pion in the lab. You measure their
> mean
> > > lifetime in the lab
> > > You generate many fast mesons moving like bats out of hell in the
> same
> > > lab. I have done this with pions having gamma factors of up to 700.
> > > You measure their mean lifetime in the lab. The second figure is
> gamma
> > > times larger than the first.
> >
> > I don't doubt that. I was careful to distinguish between experiments
> > which supported the structure of SR in general, from which we deduce
> > the expected behavior of the twins, to experiments which could be
> > mapped directly to the twin paradox.
> This is a direct test of the twins paradox, your objections
> notwithstanding. Both classes of muon are born and die in the lab. The
> ones which moved were older when they died..
>
> If you must have an apparently more direct test, there are the clocks
> flown in aircraft, compared before take-off and landing with an
> earthbound clock.
I accept the latter as a direct test of the twin paradox. It contains
the essential element of two clocks meeting at events A and B, one
clock having taken a journey, for suitable meaning of "journey".
Mere time dilation doesn't cut it, IMO, as a direct test of the twin
paradox. The twin paradox is crafted to show that time dilation,
symmetrical at constant relative velocity (the muons don't think too
much of _your_ clocks either), can be arranged to give some absolute
looking effects. There is no longer anything reciprocal when the
clocks are brought together and show different times.
If your muons were to continue living one day, while lab, accelerator,
and all the other apparatus you had been using to torment them
*poofed* out of existence, they would similarly conclude that _your_
clocks were slow pokes, and that the lab had lived longer than
unrelativistic labs were expected to.
The twin paradox is the temporal version of the Ehrenfest disk ... by
closing the loop we are forced to concede that reciprocal length and
time effects can have absolute consequences -- which we might not have
expected.
<snip>
Franz Heymann
I concede.
Franz Heymann
Shmuel (Seymour J.) Metz
at 07:53 AM, null...@aol.com (Edward Green) said:
>it's best just to use the ascii God gave us
Nice try, but your explanation is wrong. Better luck next time.
>Yes. Well, the tyro
Wrong again, boy.
>As I said, I am only faithfully reproducing what would happen if I
>wandered into his homeland
Are you still laboring under the misapprehension that this tread only
exist in sci.physics? You call me a tyro, yet you still don't
understand that you are cross-posting to sci.math and sci.logic?