[LONG] Jump Points Redux -or- Once More Into the Rubber Science mines
James Nicoll
Going back to a year old thread
This is long and being based in rubber science, nonsensical.
Sorry. I'd still like comments and critiques.
Assume the existance of something like primordial wormholes,
with the following properties:
Conservation of momentum and such, in the manner of a standard
wormhole. If you run enough stuff through one way, the endpoint from
which mass is disappearing pinches shut.
Although the path through the wormhole seems short to the
traveller, you don't actually beat photons travelling via the usual
route (So you step through to Mars in an instant or eight minutes,
depending on whose clock you are using). No FTL, at least from the
POV of the stay at homes.
The masses of the wormholes vary in a continuum, from very tiny
to extremely large, in this case from nanograms to billions of tonnes.
The end points have a slight attraction to each other that
is constant regardless of distance. It's possible but very uncommon
for two end points to come together after falling billions of light
years, which was one hint that these things existed ("Atypical Gamma
Rays Bursters" was the first paper leading to the discovery of these
things). As a result a large fraction of the wormholes in the solar
system have endpoints that are next to each other, or at least in the
same solar system (Say, 99%). There's a way to measure the length
of a wormhole from outside, and so we know the rest are distributed
throughout the galaxy (and in a few cases, the universe). WH EPs tend
to stay a low velocities wrt each other because it is hard for them
to be accelerated, interacting weakly with matter as they do.
Thanks to New Model Physics, something that address most of
the problematic areas of current physics (and no doubt leads to
new ones eventually) we know how to manipulate these wormholes so
if we can find them (and there are various ways of doing it) it
would be quite practical to exploit them (Unfortunately NMP doesn't
necessarily give us a lot of immediate new aps, because the energies
involved in getting to regions where the NMP differs from the current
models are huge. The wormholes date to the Big Bang, and each represents
a mind-boggling investment of energy).
Natural unprocessed wormholes have tiny cross sections and interact
very weakly with regular matter but they tend to gather into "Shilling
Clusters", captured in N body gravitational interactions. Look for clusters
of other objects collected by N body interactions and you will find wormholes.
Eventually, we will learn how to split WHs, so that e.g. one hundred
WH becomes two fifty tonne WH or a thousand hundred kilogram WH.
You can feed one WH endpoint through another, so WH can transport
other smaller WHs.
Is the following toy history I have in mind reasonable?
2015: Theoretical model: Proposed but of no apparent relevence to civilization.
[Date selected to be near enough that the characters are closely
linked to us, far enough away to be discarded as background before the
date rolls by]
2027: Remote Discovery: Someone checks a prediction from NMP and lo and
behold there they are, off where they can not possibly be of any use.
2030s:Probe Examination: As long as the probe is examining the other material
in the area, they might as well look at these as well.
Early 2040s: Return Mission: Self-descriptive
Late 2040s: Early Noncommercial Exploitation: Open one of them and look
through. One of the early return samples leads to Jupiter, which is a good
neighborhood to look for these (But very demanding). Open another and
demonstrate the possibility of untappable communications.
2050s: Early Military and Commerical Applications: Domesticated WHs are rare
and stinking expensive. The only stuff worth sending through them is
information and military stuff.
[Being able to pipe soldiers and materials past a front without
interacting with the front should have interesting effects on warfare].
2060: WWIII, which includes use of WH. WMD are not used, for the same reason
gas was not used in WWII. Weapons of extremely specific destruction -are-
used but don't have much to do with this thread. Two years growth
worth of people die. A number of new techiques to use WH are developed
and after the end of the war, generally declared to be the last great
war ever, they are released in to the commercial domain.
Losers are defeated but not occupied. Casualties are mostly
military personel and hapless third party nationals whose territory
gets used as a battle ground.
UN replaced by an equally hamstrung organization.
Medium Range Exploitation: A large number of potential aps are proposed
for WH, including using them to transport WH to Earth. Costs slowly come
down with time. Errors are made that in retrospect are obviously wrong.
Oddly, although this makes travelling to space cheap, it may
work against colonization because you can commute to e.g. Mars in 8
to 20 minutes. OTOH, perhaps chateaus in the Vallis Marinaris become
trendy.
Earth gets smaller (I don't forsee the end of the nation-state,
though). The entire solar system gets much smaller (although setting up
the network may take time).
Exploitation rates of WH grows in this period. This is not a
problem because there are a great many of these WHs, obeying roughly the
same size law as interplantary debris.
Some oddball programs happen in here, like sending crewed and
uncrewed probes through links to nearish (tens to thousands of LY)
stars. Time capsules get shoved through to very distant destinations,
to return after the sun burns out. At this point, it may become next
to impossible to exterminate humans, at least before the end of the
stelliferous era.
2090s: WWIV, started by the losers of WWIII. The primitive weapons of
WWIII are used in a far more modern form. Death toll five year years
population growth (Assuming there still is population growth at this
time) and this time the civilians pay the price as homelands are struck
with WESD.
Losers are defeated and occupied. A replacement for the UN's
replacement is founded, one that will definitely end war for all time
or the next century, which ever comes first.
Thanks to research in the WWIV and post-WWIV era, WH costs act
like computer costs, halving every few years. Use rate grows exponentially.
Nations become topologically complex.
2110s: Limits to Growth: Suddenly what seemed like an inexhaustible supply
seems terribly limited. Papers are published showing that current production
will peak in only two generations. Part of the problem is that even though
energy is cheap thanks to suntaps, the larger WHs are not all that useful
for the main market, Earth, being awkwardly large to move.
Civilization is Doomed plus There are too many of Those People
and only poorly thought out self-destructive state policies can save the
day!
There are still unused low mass WHs, a huge supply of cheap
energy and untapped nearby stars. Venture capitalists fund fast [1/4 C]
probes to nearby stars, intending to strip-mine them of commericially
useful WH pairs. Other expeditions are sent through to the nearer stars
(nearest linked star is Wolf 1061, a close orbiting binary almost 14 light
years away). Tax laws are tinkered to make this outreach program more
profitable because Civilization Depends on It!
Expeditions to the Kuiper and the Oort are organized but are
seen as less sexy and less likely to produce large numbers of WHs, because
matter is so spread out out there.
The "star rush" attracts large amounts of investment money,
even though the first profits can not be realised until Alpha C is
reached in the 2030s, assuming AC has exploitable WHs [On the plus side,
advances in astronomical tools mean every planet larger than Ceres out to
100 ly is known] Stock prices rise without limit. Scholarly papers are
published in the WSJ (Admittedly, never the same after the Moonies bought
it) showing why this will never end.
December, 2118: Kuiper Belt and Oort Cloud WH sources come online.
January 2119: WH splitting is demonstrated.
Suddenly the solar supply of WH has a sudden increase. Suddenly the
"Star Bubble" collapses, making trillions of dollars evaporate in a single
day. Happily the total economy is a hundred times bigger than it is today,
so that is not as bad a hit as it would be today. Scholarly articles appear
in the WSJ showing why this was inevitable.
This, of course, doesn't destroy the various probes but ownership
changes hands a lot, for increasingly smaller amounts. It's not like there
can't be a future market for the interstellar WH but they've suddenly
become much less competitive. And available to people who might be interested
in visiting the nearer stars for non WH related reasons. For example,
the potentially life-bearing worlds around AC B, AB or C might be exploitable.
[I am tempted to have the PCs be part of the Wolf 1061 expedition,
returning home in 2145 to discover the parent company long dead]
--
It's amazing how the waterdrops form: a ball of water with an air bubble
inside it and inside of that one more bubble of water. It looks so beautiful
[...]. I realized something: the world is interesting for the man who can
be surprised. -Valentin Lebedev-
Erik Max Francis
> The end points have a slight attraction to each other that
> is constant regardless of distance. It's possible but very uncommon
> for two end points to come together after falling billions of light
> years, which was one hint that these things existed ("Atypical Gamma
> Rays Bursters" was the first paper leading to the discovery of these
> things).
This doesn't sound right. What is the attraction between the two
endpoints? Is it a constant force, or a constant acceleration? (As
you've said, the endpoints have varying masses, so this makes a big
difference.)
It sounds like you're attempting to use this attraction to get most
wormhole endpoints relatively close to each other. I don't think this
is the right way to do it. For one thing, you're ignoring universal
expansion. Unless the attraction between endpoints is enormous, it's
not going to overcome Hubble expansion (you mentioned "after falling
billions of light-years"), so two endpoints of the same wormhole that
start billions of light-years apart won't get any closer. If the
endpoints start out cosmologically distant from each other (you haven't
said how they're created), I can't imagine a single instance of
endpoints colliding happening during the entire history of the Universe,
unless the endpoints start out in close proximity, which makes more
sense anyway, and results in not needing to handwave rationales for why
they're close together after the fact.
> WH EPs tend
> to stay a low velocities wrt each other because it is hard for them
> to be accelerated, interacting weakly with matter as they do.
If they interact weakly with matter, you're going to have a hard time
explaining how matter-based spacecraft manage to use them to travel
around.
> Eventually, we will learn how to split WHs, so that e.g. one
> hundred
> WH becomes two fifty tonne WH or a thousand hundred kilogram WH.
You haven't said what purpose the wormhole masses play, so it's not
clear what benefit splitting wormhole has.
--
Erik Max Francis && m...@alcyone.com && http://www.alcyone.com/max/
__ San Jose, CA, USA && 37 20 N 121 53 W && &tSftDotIotE
/ \
\__/ It is impossible to love and be wise.
-- Francis Bacon
Aaron Bergman
Erik Max Francis <m...@alcyone.com> wrote:
> It sounds like you're attempting to use this attraction to get most
> wormhole endpoints relatively close to each other. I don't think this
> is the right way to do it. For one thing, you're ignoring universal
> expansion. Unless the attraction between endpoints is enormous, it's
> not going to overcome Hubble expansion (you mentioned "after falling
> billions of light-years"), so two endpoints of the same wormhole that
> start billions of light-years apart won't get any closer. If the
> endpoints start out cosmologically distant from each other (you haven't
> said how they're created), I can't imagine a single instance of
> endpoints colliding happening during the entire history of the Universe,
> unless the endpoints start out in close proximity, which makes more
> sense anyway, and results in not needing to handwave rationales for why
> they're close together after the fact.
What's worse is that, if wormhole creation takes place pre-inflation,
you better produce them in enough numbers so that there's more than one
in our horizon.
Aaron
pervect
wrote:
>
> Going back to a year old thread
>
> This is long and being based in rubber science, nonsensical.
>Sorry. I'd still like comments and critiques.
>
> Assume the existance of something like primordial wormholes,
>with the following properties:
>
> Conservation of momentum and such, in the manner of a standard
>wormhole. If you run enough stuff through one way, the endpoint from
>which mass is disappearing pinches shut.
>
> Although the path through the wormhole seems short to the
>traveller, you don't actually beat photons travelling via the usual
>route (So you step through to Mars in an instant or eight minutes,
>depending on whose clock you are using). No FTL, at least from the
>POV of the stay at homes.
How does this work exactly? For instance, if you step through the
wormhole to mars, then back to earth, how much time elapses for the
round trip on the traveller's clock, and on an Earth clock?
The constant force thing worries me a bit, but I'm going to have to
think about that some more before I open my mouth.
Chuck Stewart
> What's worse is that, if wormhole creation takes place pre-inflation,
> you better produce them in enough numbers so that there's more than one
> in our horizon.
"Passengers will please check that they have all their personal belongings
before exiting the light cone..."
>Aaron
--
Chuck Stewart
"Anime-style catgirls: Threat? Menace? Or just studying algebra?"
Serg
> > Although the path through the wormhole seems short to the
> >traveller, you don't actually beat photons travelling via the usual
> >route (So you step through to Mars in an instant or eight minutes,
> >depending on whose clock you are using). No FTL, at least from the
> >POV of the stay at homes.
>
> How does this work exactly? For instance, if you step through the
> wormhole to mars, then back to earth, how much time elapses for the
> round trip on the traveller's clock, and on an Earth clock?
Each wormhole travel takes exactly or little more time as light travel
from one end to other through normal space by the external clock, but
little time by the traveller clock - traveller freeze inside the
wormhole. It can be handwaved as while wormhole ends move away one
from another after big bang they should be in dynamical eqilibrium
with external space (you know, rolling gravitons pushing internal
metric curvature :-) ).
Brendan Hogg
I've been lurking here for a while, intending to post some very rubber
science at some indeterminate future point when I start work on a
particularly pulpy SF story idea I'm germinating, so I suppose I ought
to do what I can to contribute to the furtherance of rubber science.
[Warning: this reply is if anything longer than the original post]
On 25 Nov 2003, James Nicoll wrote:
>
> Going back to a year old thread
>
> This is long and being based in rubber science, nonsensical.
> Sorry. I'd still like comments and critiques.
>
> Assume the existance of something like primordial wormholes,
> with the following properties:
>
> Conservation of momentum and such, in the manner of a standard
> wormhole. If you run enough stuff through one way, the endpoint from
> which mass is disappearing pinches shut.
What's the mechanism by which this happens? Is the mass in the endpoint
flying off to conserve local momentum as you walk through? And when
you leave at the other hand, other mass is attracted towards it to
compensate your local momentum there (thus keeping the total WH mass
constant as you pass through)? Or have I hopelessly misunderstood what
you mean here?
> Although the path through the wormhole seems short to the
> traveller, you don't actually beat photons travelling via the usual
> route (So you step through to Mars in an instant or eight minutes,
> depending on whose clock you are using). No FTL, at least from the
> POV of the stay at homes.
I don't see how you're getting FTL from anyone's POV, if wormhole travel
doesn't beat photons. (Well, I suppose you could do a Timelike Infinity
style time machine, taking one wormhole end off at relativistic speeds
while the other stays home.) Or are you going for
travel-down-the-wormhole being exactly c (in which case the subjective
time for the traveller is 0, not short, and my brain breaks the same way
it does when trying to keep things straight in Ken MacLeod's Engines of
Light books[1])?
> The masses of the wormholes vary in a continuum, from very tiny
> to extremely large, in this case from nanograms to billions of tonnes.
There are several things that aren't clear to me presently. For
instance: is the mass of the wormhole correlated with any other
properties? (Length, for example? [but then the lengths are contracting,
according to this business below about the constant attraction][2]) How
is the mass distributed in the wormhole? Do the two endpoints each have
mass, with a massless connection between them, or what?
> The end points have a slight attraction to each other that
> is constant regardless of distance. It's possible but very uncommon
> for two end points to come together after falling billions of light
> years, which was one hint that these things existed ("Atypical Gamma
> Rays Bursters" was the first paper leading to the discovery of these
> things). As a result a large fraction of the wormholes in the solar
> system have endpoints that are next to each other, or at least in the
> same solar system (Say, 99%). There's a way to measure the length
> of a wormhole from outside, and so we know the rest are distributed
> throughout the galaxy (and in a few cases, the universe). WH EPs tend
> to stay a low velocities wrt each other because it is hard for them
> to be accelerated, interacting weakly with matter as they do.
There are several things about this set up that bother me. I'm not sure
that various statements you've made here are all compatible with one
another. Specifically, the constant force law thing bugs me.
Ridiculously oversimplistic Newtonian treatment which I think
demonstrates the problem, even though it's hopelessly hopelessly wrong
(forgive the ASCII art & eqns):
EP1--> ......................................... <--EP2
<--------------------r------------------>
ma = N (the "Nicoll constant") => a = N/m
so we integrate up and get v = Nt/m + c_0 and r = Nt^2/2m + tc_0 + c1
Obviously, this doesn't work once we reach the relativistic regime and m
becomes a function of t as well (and to do it really properly we should
take into account the cosmological expansion, etc., etc.), but if the
wormholes have been falling towards each other since the beginning of
time, by now I would expect them to be moving at very close to c, unless N
is very very small (but if it's that small, it's probably not winning
against the cosmological expansion, as Erik points out). So the time from
a wormhole reaching the solar system scale to its complete collapse is
very small (a year or two, tops, if we're defining
solar-system-scale==Oort cloud). So while it's just, _just_ possible that
we _happen_ to live at the time when the wormholes are about to collapse,
but haven't yet, it seems very very unlikely. And when it does happen,
we'll probably all be wiped out by the gamma rays, which would muck up
your timeline a little.
In summary, I think you can pick any two of the following items from your
current setup, but all three together won't work:
1) constant attraction with distance (unless "constant attraction" doesn't
mean force, as I've interpreted it to)
2) Most wormholes in-solar-system
3) All life in solar system not about to be wiped out by gamma ray bursts
Something like the strong force law for quarks might work better
(force proportional to distance), giving you large attraction at
large separation so that they get pulled close together, but then
small attraction at small separation so that they don't collapse. But the
easiest thing seems to be to go for Erik's solution of having them start
off close together, since the reason you're invoking this seems to be to
achieve #2.
> Thanks to New Model Physics, something that address most of
> the problematic areas of current physics (and no doubt leads to
> new ones eventually) we know how to manipulate these wormholes so
> if we can find them (and there are various ways of doing it) it
> would be quite practical to exploit them (Unfortunately NMP doesn't
> necessarily give us a lot of immediate new aps, because the energies
> involved in getting to regions where the NMP differs from the current
> models are huge.
Don't forget about phenomenology; NMP may have implications observable at
lower energy regimes. (Maybe you could tie in massive neutrinos somewhere
along the line, just for fun ...)
> The wormholes date to the Big Bang, and each represents
> a mind-boggling investment of energy).
Just curious: what percentage of the dark matter do they make up?
Actually, the more I think about the effects of the presence of these
things at early times, the more bothered I become. If (and it's a fairly
big if) pressure gradients/what have you work across the two ends of the
wormhole, then their presence during the early universe is surely going to
act to smooth out the pre-recombination plasma. Hrm, you could probably
work backward from CMB anisotropies to the spectrum of wormhole lengths,
or something. In fact, I suspect we'd have evidence by now of
early-universe wormholes from just this sort of thing, unless they do
exist on very short length scales, but that's what you require anyway, so
no problem.
> Natural unprocessed wormholes have tiny cross sections and interact
> very weakly with regular matter but they tend to gather into "Shilling
> Clusters", captured in N body gravitational interactions. Look for clusters
> of other objects collected by N body interactions and you will find wormholes.
I'm a bit confused here; it seems to me that wormholes must interact by
gravity, since they have mass, but you're making a point here of talking
about N-body interactions, as though these are somehow more likely to
affect them than any other gravitational interaction. (And earlier, you
said something about them staying at low velocities wrt one another, which
I didn't really understand either.)
(Actually, if gravity does work on wormholes, we'll have to assume that
their distribution in the solar system is quite smooth, or they'd create
noticeable perturbations in planetary orbits.)
> Eventually, we will learn how to split WHs, so that e.g. one hundred
> WH becomes two fifty tonne WH or a thousand hundred kilogram WH.
Someone else has already asked what the apps of this are, and I was
going to second it, but it sounds from your timeline like there are
various things for which wormholes are useful fairly independently of
their size (comms?), so the more the merrier, and therefore splitting is
helpful since it gives you two WHs for the price of one.
> You can feed one WH endpoint through another, so WH can transport
> other smaller WHs.
>
> Is the following toy history I have in mind reasonable?
>
>
>
> 2015: Theoretical model: Proposed but of no apparent relevence to civilization.
How widely accepted is it? Since there's no proof (yet) surely it's just
one of a number of competing possibilities for New Physics.
> [Date selected to be near enough that the characters are closely
> linked to us, far enough away to be discarded as background before the
> date rolls by]
>
> 2027: Remote Discovery: Someone checks a prediction from NMP and lo and
> behold there they are, off where they can not possibly be of any use.
>
> 2030s:Probe Examination: As long as the probe is examining the other material
> in the area, they might as well look at these as well.
>
> Early 2040s: Return Mission: Self-descriptive
>
> Late 2040s: Early Noncommercial Exploitation: Open one of them and look
> through. One of the early return samples leads to Jupiter, which is a good
> neighborhood to look for these (But very demanding). Open another and
> demonstrate the possibility of untappable communications.
This early part feels a little too quick for me, but I think it's
a failure of my imagination rather than the inherent plausibility
of the history. I think it's the speed with which we go from remote
discovery to noncommercial exploitation. But as I say, it's probably
me (and my deep, deep cynicism about the likelihood of decent near-future
space exploration on lack-of-political-will grounds), not the
timeline: indeed, it seems to track fairly well with the time between the
discovery of QM/nuclear structure and the first applications of that ...
> 2050s: Early Military and Commerical Applications: Domesticated WHs are rare
> and stinking expensive. The only stuff worth sending through them is
> information and military stuff.
>
> [Being able to pipe soldiers and materials past a front without
> interacting with the front should have interesting effects on warfare].
How do you manipulate the EPs to be where you want them to be? If the EP
has to be moved in by non-WH means (at least for the first WH at a certain
location) surely you're going to have to stage at least a raid to
establish your wormhole "beachhead"? And then you'll be limited in how
much stuff you can send through by the mmtm-conservation thing. (Though
of course you can send back prisoners, casualties, etc. Maybe there are
entire squads detailed to finding loose material to pass through to keep
the wormhole open? Or then again do you just go for a one-shot, throw
through all the mass the wormhole will allow as quickly as
possible to blitzkrieg the other side?)
<snip WWIII and its aftermath -- WH tech originally developed for military
use now commercially avaiable>
>
> Medium Range Exploitation: A large number of potential aps are proposed
> for WH, including using them to transport WH to Earth. Costs slowly come
> down with time. Errors are made that in retrospect are obviously wrong.
>
> Oddly, although this makes travelling to space cheap, it may
> work against colonization because you can commute to e.g. Mars in 8
> to 20 minutes. OTOH, perhaps chateaus in the Vallis Marinaris become
> trendy.
Then again, if Earth is filling up (which, even if you do kill two years'
worth of people, it seems to be) you've suddenly opened a flood of real
estate. If only the other planets had the breathable atmospheres '30s SF
tells us they do, you'd definitely get colonisation; as it is, it'll
probably depend on what you decide the cost of big domes/terraforming is
(OTOH, wormholes make constant-supply operations feasible, so some
people[3] might decide they don't need to worry about self-sufficiency,
which seems to be one of the main limiters on most currently-mooted
colonisation scenarios).
> Earth gets smaller (I don't forsee the end of the nation-state,
> though). The entire solar system gets much smaller (although setting up
> the network may take time).
>
> Exploitation rates of WH grows in this period. This is not a
> problem because there are a great many of these WHs, obeying roughly the
> same size law as interplantary debris.
Why? I am not remotely an expert on such things, but I was under the
impression that the size law of interplanetary debris was influenced by
collisions between asteroids, etc., which wormholes presumably aren't
subject to.
> Some oddball programs happen in here, like sending crewed and
> uncrewed probes through links to nearish (tens to thousands of LY)
> stars. Time capsules get shoved through to very distant destinations,
> to return after the sun burns out. At this point, it may become next
> to impossible to exterminate humans, at least before the end of the
> stelliferous era.
I like these. (Have you been reading Baxter, by any chance?)
<WWIV happens>
>
> Thanks to research in the WWIV and post-WWIV era, WH costs act
> like computer costs, halving every few years. Use rate grows exponentially.
>
> Nations become topologically complex.
Just wanted to say that this pinged my
"throwaway-line-hinting-at-Cool-Stuff-o-meter" (even after I recently
recalibrated it for reading Stross).
<We're running out of wormholes, oh no>
> Civilization is Doomed plus There are too many of Those People
> and only poorly thought out self-destructive state policies can save the
> day!
>
> There are still unused low mass WHs, a huge supply of cheap
> energy and untapped nearby stars. Venture capitalists fund fast [1/4 C]
> probes to nearby stars, intending to strip-mine them of commericially
> useful WH pairs. Other expeditions are sent through to the nearer stars
> (nearest linked star is Wolf 1061, a close orbiting binary almost 14 light
> years away). Tax laws are tinkered to make this outreach program more
> profitable because Civilization Depends on It!
If wormhole-travel is near-as-dammit-to-c, then I think the Wolf
expedition is actually going to be the first to return an
extra-solar-system wormhole (28 years to and form Wolf vs 32 years to
and from AC at c/4), unless you increase the speed of the fast probes.[4]
Also, couldn't you contact the earlier "oddball" missions that went
to other solar systems and ask them to pipe a few wormholes back through,
if they'd be so kind? Oh, wait, the message would take as long to get
down the wormhole as a new, specially-equipped-for-strip-mining starship,
wouldn't it? Ignore me ...
> Expeditions to the Kuiper and the Oort are organized but are
> seen as less sexy and less likely to produce large numbers of WHs, because
> matter is so spread out out there.
>
> The "star rush" attracts large amounts of investment money,
> even though the first profits can not be realised until Alpha C is
> reached in the 2030s, assuming AC has exploitable WHs [On the plus side,
You mean 2130s, I assume. Also, why wouldn't AC have exploitable WHs if
we do? (principle of mediocrity)
> advances in astronomical tools mean every planet larger than Ceres out to
> 100 ly is known] Stock prices rise without limit. Scholarly papers are
> published in the WSJ (Admittedly, never the same after the Moonies bought
> it) showing why this will never end.
>
> December, 2118: Kuiper Belt and Oort Cloud WH sources come online.
>
> January 2119: WH splitting is demonstrated.
>
> Suddenly the solar supply of WH has a sudden increase. Suddenly the
> "Star Bubble" collapses, making trillions of dollars evaporate in a single
> day. Happily the total economy is a hundred times bigger than it is today,
> so that is not as bad a hit as it would be today. Scholarly articles appear
> in the WSJ showing why this was inevitable.
>
> This, of course, doesn't destroy the various probes but ownership
> changes hands a lot, for increasingly smaller amounts. It's not like there
> can't be a future market for the interstellar WH but they've suddenly
> become much less competitive. And available to people who might be interested
> in visiting the nearer stars for non WH related reasons. For example,
> the potentially life-bearing worlds around AC B, AB or C might be exploitable.
OK, so let me see if I've got this straight? Expeditions have gone to
non-WH connected stars to return WHs from them. So as soon as these
missions return (or arrive, in my footnote [4] scenario), we have a
wormhole connection to those star systems which we can buy cheaply and use
for whatever we want because its original purpose (WH retrieval) is no
longer competitive?
> [I am tempted to have the PCs be part of the Wolf 1061 expedition,
> returning home in 2145 to discover the parent company long dead]
Oooh, that sounds like it could be fun, particularly if you prime them
with lots of information about their position within the company, and why
corporate politics is v. important to their success, etc.
Cheers,
Brendan
[1] I don't know why, but I keep having to remind myself very consciously
about the non-simultaneity of events on Earth and the Second Sphere. I
don't seem to be able to wrap my head round the consequences of
lightspeed travel, whereas I'm mostly fine with time dilation, etc.
[2] What if mass correlates with internal length, so it takes
longer subjectively to travel through a high-mass wormhole, even if its
two endpoints are right next door to each other? Could have interesting
implications ...
[3] Not me.
[4] Or have the expeditions taken one end of the biggest wormhole still
available with them, and are going to pump smaller ones through it back to
Earth? In which case they only take 20 years to return the first WH. In
fact, since you've explicitly stated that the really big ones aren't
commercially useful in and of themselves, taking an endpoint of one along
would be perfect, and the company can build a big terminal at the
stay-at-home end and shuttle the WHs to Earth from there. (Especially
good since the larger the WH the more smaller ones you can pump through
it.)
Mark Fergerson
>
> Going back to a year old thread
>
> This is long and being based in rubber science, nonsensical.
> Sorry. I'd still like comments and critiques.
>
> Assume the existance of something like primordial wormholes,
> with the following properties:
Wormholes have always bothered me for several reasons,
some of which bear here.
> Conservation of momentum and such, in the manner of a standard
> wormhole. If you run enough stuff through one way, the endpoint from
> which mass is disappearing pinches shut.
WRT what is momentum conserved, the rest frame of the WH?
Since both ends are (usually) moving together as you say
below, what _is_ its rest frame, the center of mass of the
endpoints? How is that defined? Can you detect the "path" of
the WH without knowing where the endpoints are and find the
COM? How do the COMs of different WH pairs relate? This
brings us perilously close to a Universal Reference Frame.
> Although the path through the wormhole seems short to the
> traveller, you don't actually beat photons travelling via the usual
> route (So you step through to Mars in an instant or eight minutes,
> depending on whose clock you are using). No FTL, at least from the
> POV of the stay at homes.
If travel is at c (as seen from outside) then travelers
are accelerated "instantaneously" to c upon entry and
decelerated similarly upon exit. Doesn't this hurt just a
little bit?
How about tidal forces?
For that matter, gravity and time are interrelated (the
deeper you go in a gravity well, the slower time runs) so
the rate of time at the ends of a wormhole will at first
glance be the same except they're embedded in whatever local
G field obtains (not to mention possible Relativistic
effects if one or both ends are moving quickly, say orbiting
a neutron star) which will not likely be identical. So,
either you have local time gradients at both ends (which
differ) or your NMP will have to account for the difference
somehow. For the neutron star case, there will also be a
gravitational gradient between the endpoints; how does this
affect travel? Is that why travel isn't instantaneous? Does
travel time depend on the environment of the endpoints?
The time-rate difference between ends also screws up
momentum conservation depending where you observe from.
> The masses of the wormholes vary in a continuum, from very tiny
> to extremely large, in this case from nanograms to billions of tonnes.
Why, other than story convenience? If they're primordial
I'd expect them to be in a narrower size range (larger ones
only) since the energies available to form them would have
been in the "extreme" range by today's standards and smaller
ones would have a longer time to coalesce.
> The end points have a slight attraction to each other that
> is constant regardless of distance. It's possible but very uncommon
> for two end points to come together after falling billions of light
> years, which was one hint that these things existed ("Atypical Gamma
> Rays Bursters" was the first paper leading to the discovery of these
> things). As a result a large fraction of the wormholes in the solar
> system have endpoints that are next to each other, or at least in the
> same solar system (Say, 99%). There's a way to measure the length
> of a wormhole from outside, and so we know the rest are distributed
> throughout the galaxy (and in a few cases, the universe). WH EPs tend
> to stay a low velocities wrt each other because it is hard for them
> to be accelerated, interacting weakly with matter as they do.
Same arguments as other mention, except I'll mention that
either they're captured during galaxy formation or they
influenced the process, or even may explain some part of
star and hence solar system formation. BTW, does your NMP
have Cosmic Strings? How do WHs relate to them?
Why do the ends attract each other, some sort of tension
in the throat? That sounds like positive energy. What holds
them open (I thought negative energy was required)?
> Thanks to New Model Physics, something that address most of
> the problematic areas of current physics (and no doubt leads to
> new ones eventually) we know how to manipulate these wormholes so
> if we can find them (and there are various ways of doing it) it
> would be quite practical to exploit them (Unfortunately NMP doesn't
> necessarily give us a lot of immediate new aps, because the energies
> involved in getting to regions where the NMP differs from the current
> models are huge. The wormholes date to the Big Bang, and each represents
> a mind-boggling investment of energy).
Hence they ought to be large (for sufficient values, etc.).
> Natural unprocessed wormholes have tiny cross sections and interact
> very weakly with regular matter but they tend to gather into "Shilling
> Clusters", captured in N body gravitational interactions. Look for clusters
> of other objects collected by N body interactions and you will find wormholes.
If they interact that weakly they will, say, form loose
shells around the clusters at Trojan points?
> Eventually, we will learn how to split WHs, so that e.g. one hundred
> WH becomes two fifty tonne WH or a thousand hundred kilogram WH.
>
> You can feed one WH endpoint through another, so WH can transport
> other smaller WHs.
Wait: what happens if you don't bring both ends through?
Do you get options when you enter one end? Or do you have to
shield the transported WH so it doesn't collapse the outer
one? Do they coalesce like ordinary black holes to get
bigger ones? This might help explain the size range except I
see no natural way to get smaller ones.
What happens if the ends of a given WH finally meet? What
happens if the ends of different WHs coalesce during transport?
> Is the following toy history I have in mind reasonable?
>
>
>
> 2015: Theoretical model: Proposed but of no apparent relevence to civilization.
>
> [Date selected to be near enough that the characters are closely
> linked to us, far enough away to be discarded as background before the
> date rolls by]
>
> 2027: Remote Discovery: Someone checks a prediction from NMP and lo and
> behold there they are, off where they can not possibly be of any use.
What, bits of stuff appearing out of nowhere with a
peculiar velocity distribution or something?
> 2030s:Probe Examination: As long as the probe is examining the other material
> in the area, they might as well look at these as well.
It'd be fun if said probe accidentally falls through and
sends pictures of a close binary back or something...
> Early 2040s: Return Mission: Self-descriptive
then returns to Sol system.
> Late 2040s: Early Noncommercial Exploitation: Open one of them and look
> through. One of the early return samples leads to Jupiter, which is a good
> neighborhood to look for these (But very demanding). Open another and
> demonstrate the possibility of untappable communications.
"Open one"? Are they naturally "closed"?
> 2050s: Early Military and Commerical Applications: Domesticated WHs are rare
> and stinking expensive. The only stuff worth sending through them is
> information and military stuff.
>
> [Being able to pipe soldiers and materials past a front without
> interacting with the front should have interesting effects on warfare].
And Internet security, if they can link planetary Nets.
> 2060: WWIII, which includes use of WH. WMD are not used, for the same reason
> gas was not used in WWII. Weapons of extremely specific destruction -are-
> used but don't have much to do with this thread. Two years growth
> worth of people die. A number of new techiques to use WH are developed
> and after the end of the war, generally declared to be the last great
> war ever, they are released in to the commercial domain.
>
> Losers are defeated but not occupied. Casualties are mostly
> military personel and hapless third party nationals whose territory
> gets used as a battle ground.
Can endpoints be permanently and safely emplaced on
Earth's surface? That'd permit a J-bomb (see Hogan's _The
Genesis Machine_) type reason not to occupy; the former bad
guys get fractious, you send through a nuke (of course, you
put the other endpoint in orbit so the bad guys have to pay
the G-related energy penalty to retaliate or pre-empt).
> UN replaced by an equally hamstrung organization.
>
> Medium Range Exploitation: A large number of potential aps are proposed
> for WH, including using them to transport WH to Earth. Costs slowly come
> down with time. Errors are made that in retrospect are obviously wrong.
>
> Oddly, although this makes travelling to space cheap, it may
> work against colonization because you can commute to e.g. Mars in 8
> to 20 minutes. OTOH, perhaps chateaus in the Vallis Marinaris become
> trendy.
Got it; as in other Jumpgate stories, large volumes of
space not near gates remain unexplored.
> Earth gets smaller (I don't forsee the end of the nation-state,
> though). The entire solar system gets much smaller (although setting up
> the network may take time).
>
> Exploitation rates of WH grows in this period. This is not a
> problem because there are a great many of these WHs, obeying roughly the
> same size law as interplantary debris.
Why, dammit?
> Some oddball programs happen in here, like sending crewed and
> uncrewed probes through links to nearish (tens to thousands of LY)
> stars. Time capsules get shoved through to very distant destinations,
> to return after the sun burns out. At this point, it may become next
> to impossible to exterminate humans, at least before the end of the
> stelliferous era.
I'd think somebody would find a way to weaponize the
things as above; that'd liven things up during this period.
> 2090s: WWIV, started by the losers of WWIII. The primitive weapons of
> WWIII are used in a far more modern form. Death toll five year years
> population growth (Assuming there still is population growth at this
> time) and this time the civilians pay the price as homelands are struck
> with WESD.
>
> Losers are defeated and occupied. A replacement for the UN's
> replacement is founded, one that will definitely end war for all time
> or the next century, which ever comes first.
The J-bomb trick doesn't work any more.
> Thanks to research in the WWIV and post-WWIV era, WH costs act
> like computer costs, halving every few years. Use rate grows exponentially.
>
> Nations become topologically complex.
Or irrelevant.
> 2110s: Limits to Growth: Suddenly what seemed like an inexhaustible supply
> seems terribly limited. Papers are published showing that current production
> will peak in only two generations. Part of the problem is that even though
> energy is cheap thanks to suntaps, the larger WHs are not all that useful
> for the main market, Earth, being awkwardly large to move.
Suntaps! Now there's a weaponization concept.
> Civilization is Doomed plus There are too many of Those People
> and only poorly thought out self-destructive state policies can save the
> day!
>
> There are still unused low mass WHs, a huge supply of cheap
> energy and untapped nearby stars. Venture capitalists fund fast [1/4 C]
> probes to nearby stars, intending to strip-mine them of commericially
> useful WH pairs. Other expeditions are sent through to the nearer stars
> (nearest linked star is Wolf 1061, a close orbiting binary almost 14 light
> years away). Tax laws are tinkered to make this outreach program more
> profitable because Civilization Depends on It!
<snip>
> December, 2118: Kuiper Belt and Oort Cloud WH sources come online.
>
> January 2119: WH splitting is demonstrated.
Wait; why did this take so long? Theoretical
considerations from coalescence should have made it happen
much earlier.
> Suddenly the solar supply of WH has a sudden increase. Suddenly the
> "Star Bubble" collapses, making trillions of dollars evaporate in a single
> day. Happily the total economy is a hundred times bigger than it is today,
> so that is not as bad a hit as it would be today. Scholarly articles appear
> in the WSJ showing why this was inevitable.
Gonna have excerpts from this WSJ at chapter beginnings a
la Blish's _Cities in Flight_?
> This, of course, doesn't destroy the various probes but ownership
> changes hands a lot, for increasingly smaller amounts. It's not like there
> can't be a future market for the interstellar WH but they've suddenly
> become much less competitive. And available to people who might be interested
> in visiting the nearer stars for non WH related reasons. For example,
> the potentially life-bearing worlds around AC B, AB or C might be exploitable.
Why would the competition be decreased? Can WHs be stretched?
> [I am tempted to have the PCs be part of the Wolf 1061 expedition,
> returning home in 2145 to discover the parent company long dead]
Almost inevitable.
Mark L. Fergerson
pervect
<ppx...@unix.ccc.nottingham.ac.uk> wrote:
><delurk>
>What's the mechanism by which this happens? Is the mass in the endpoint
>flying off to conserve local momentum as you walk through? And when
>you leave at the other hand, other mass is attracted towards it to
>compensate your local momentum there (thus keeping the total WH mass
>constant as you pass through)? Or have I hopelessly misunderstood what
>you mean here?
That's how a standard wormhole works - his approach seems to work the
same way.
>There are several things about this set up that bother me. I'm not sure
>that various statements you've made here are all compatible with one
>another. Specifically, the constant force law thing bugs me.
>
>Ridiculously oversimplistic Newtonian treatment which I think
>demonstrates the problem, even though it's hopelessly hopelessly wrong
>(forgive the ASCII art & eqns):
>
>EP1--> ......................................... <--EP2
> <--------------------r------------------>
>
>ma = N (the "Nicoll constant") => a = N/m
>
>so we integrate up and get v = Nt/m + c_0 and r = Nt^2/2m + tc_0 + c1
>
>Obviously, this doesn't work once we reach the relativistic regime and m
>becomes a function of t as well (and to do it really properly we should
>take into account the cosmological expansion, etc., etc.), but if the
>wormholes have been falling towards each other since the beginning of
>time, by now I would expect them to be moving at very close to c, unless N
>is very very small (but if it's that small, it's probably not winning
>against the cosmological expansion, as Erik points out). So the time from
>a wormhole reaching the solar system scale to its complete collapse is
>very small (a year or two, tops, if we're defining
>solar-system-scale==Oort cloud). So while it's just, _just_ possible that
>we _happen_ to live at the time when the wormholes are about to collapse,
>but haven't yet, it seems very very unlikely. And when it does happen,
>we'll probably all be wiped out by the gamma rays, which would muck up
>your timeline a little.
I think the assumption is that the wormholes will scatter (off each
other, if nothing else). So you'll have some mean free path, after
which the velocity buildup will be interrupted. This also ties in
with the point about gamma ray bursts - a lot of energy will be
released when they collide if the mean free path is long, the energy
will be on average the Nicoll constant times the mean free path.
I'm not sure what this implies about the temperature distribution.
I.e. how "hot" are the wormholes? (This is just a synonym for the
velocity distribution). If they're giving off gamma ray bursts, that
would seem to argue that they're still very "hot", so the static
picture used later on in the article wouldn't work very well.
It still bothers me that every other force we know of drops off as
inverse sqaure or faster - this force doesn't fit that model. But I
haven't been able to think of anything to back up my unease.
pervect
wrote:
> WRT what is momentum conserved, the rest frame of the WH?
The momentum is conserved in all frames. This is possible only
because the mass of the wormhole ends can change.
>
> For that matter, gravity and time are interrelated (the
>deeper you go in a gravity well, the slower time runs) so
>the rate of time at the ends of a wormhole will at first
>glance be the same except they're embedded in whatever local
>G field obtains (not to mention possible Relativistic
>effects if one or both ends are moving quickly, say orbiting
>a neutron star) which will not likely be identical. So,
>either you have local time gradients at both ends (which
>differ) or your NMP will have to account for the difference
>somehow. For the neutron star case, there will also be a
>gravitational gradient between the endpoints; how does this
>affect travel? Is that why travel isn't instantaneous? Does
>travel time depend on the environment of the endpoints?
The difference in time rates between a fast moving and a slow moving
wormhole is one way (a fairly important one) in which wormholes turn
into time machines. I think the main idea of the NMP is to avoid time
machines (?) - I'm not positive, not being the author, but that's the
impression I got. So this looks like a potential problem with NMP
(IMO).
> The time-rate difference between ends also screws up
>momentum conservation depending where you observe from.
For GR, you usually measure energy and momentum from an asymptotically
flat background region of space-time to keep them conserved. (I
remember reading some fine print that suggested there were other ways
to keep energy conserved, but they weren't very common). Global
energy is not conserved in arbitrary coordinates in GR, you do need
some conditions on your coordinate system to keep global energy
conservation. Local energy conservation is always true. Asymptotic
flatness is the usual condition that's assumed for global energy
conservation. Note that momentum conservation goes hand in hand with
energy conservation (they're part of the same 4-vector). For more
detail check out the sci.physics FAQ about energy conservation in GR.
It doesn't matter with what velocity the asymptotically flat frame is
moving. There may be a possible issue with my understanding here, the
issue being whether or not it is possible to create an asymptotically
flat frame around a moving mass. Intuitively, this should be
possible, but I can't confirm this rigorously. I've never seen an
expression of the "gravitational field" <note the scare quotes> of a
moving mass - unless you count the Aichelberg-Sexyl boost (but that
only works in the limit of very high velocities).
Bryan Derksen
wrote:
>It still bothers me that every other force we know of drops off as
>inverse sqaure or faster - this force doesn't fit that model. But I
>haven't been able to think of anything to back up my unease.
In real-world physics, when one tries to turn a wormhole into a
timehole you get a stream of virtual particles circling continuously
through the wormhole's throat. Perhaps you could handwave something
like this, a "beam" of virtual particles that connects the two mouths
of the wormhole through normal space and acts to pull them together?
Since the beam wouldn't be omnidirectional, it wouldn't have to follow
inverse square.
One could perhaps imagine the wormhole as a loop in spacetime that's
got a sort of "tension" trying to shrink it. Since the throat can't
get any shorter, the tension acts to pull its mouths towards each
other through normal space. In this case one can fiddle with the way
spacetime's "elasticity" works to get constant force.
Did my waving hands accidentally knock over any significant known
physics? :)
James Nicoll
pervect <per...@invalid.invalid> wrote:
>On 25 Nov 2003 13:33:12 -0500, jdni...@panix.com (James Nicoll)
>wrote:
>
>>
>> Going back to a year old thread
>>
>> This is long and being based in rubber science, nonsensical.
>>Sorry. I'd still like comments and critiques.
>>
>> Assume the existance of something like primordial wormholes,
>>with the following properties:
>>
>> Conservation of momentum and such, in the manner of a standard
>>wormhole. If you run enough stuff through one way, the endpoint from
>>which mass is disappearing pinches shut.
>>
>> Although the path through the wormhole seems short to the
>>traveller, you don't actually beat photons travelling via the usual
>>route (So you step through to Mars in an instant or eight minutes,
>>depending on whose clock you are using). No FTL, at least from the
>>POV of the stay at homes.
>
>How does this work exactly? For instance, if you step through the
>wormhole to mars, then back to earth, how much time elapses for the
>round trip on the traveller's clock, and on an Earth clock?
From Earth's POV, up to 40 minutes for the round trip.
From the travellers POV, very little time.
>The constant force thing worries me a bit, but I'm going to have to
>think about that some more before I open my mouth.
Actually, I was hoping forces would work through the throat
of the wormhole but it occurs to me that that won't work. Also it
seems like there's this period of intense acceleration through the
throat, which make me wonder what happens if you try to change your
mind about going through (Stick a hand in and try to get it back).
And about differential acceleration across one's body.
This thread is an example of how trying to avoid unsavory
consequences of regular wormholes [time travel and FTL] can have
other unwanted effects.
Mark Fergerson
> On Wed, 26 Nov 2003 10:55:56 -0700, Mark Fergerson <nu...@biz.ness>
> wrote:
>
>
>
>> WRT what is momentum conserved, the rest frame of the WH?
>
>
> The momentum is conserved in all frames. This is possible only
> because the mass of the wormhole ends can change.
So what happens to conservation of mass? Does the other
end change in tandem? What mechanism communicates the signal
to "change mass" between the ends of the WH? It better not
be FTL either.
>> For that matter, gravity and time are interrelated (the
>>deeper you go in a gravity well, the slower time runs) so
>>the rate of time at the ends of a wormhole will at first
>>glance be the same except they're embedded in whatever local
>>G field obtains (not to mention possible Relativistic
>>effects if one or both ends are moving quickly, say orbiting
>>a neutron star) which will not likely be identical. So,
>>either you have local time gradients at both ends (which
>>differ) or your NMP will have to account for the difference
>>somehow. For the neutron star case, there will also be a
>>gravitational gradient between the endpoints; how does this
>>affect travel? Is that why travel isn't instantaneous? Does
>>travel time depend on the environment of the endpoints?
>
>
> The difference in time rates between a fast moving and a slow moving
> wormhole is one way (a fairly important one) in which wormholes turn
> into time machines. I think the main idea of the NMP is to avoid time
> machines (?) - I'm not positive, not being the author, but that's the
> impression I got. So this looks like a potential problem with NMP
> (IMO).
Now it's worse; as the ends are changing mass as above,
the time rates vary as well. This will affect the "send" and
"receive" times of the signal. OTOH that could be fixed if
the length of the WH connection always changes to keep the
signal moving at c, but how does it know to do that if the
signal hasn't gotten all the way yet? Not to mention that
the signal has to tell the other end not just to change, but
which way and by how much. ISTM there's gonna be a
Doppler-related bugger factor in there somewhere. Either
that or the endpoints' apparent masses will fluctuate as
signals bounce back and forth. That will do weird things to
their movements.
If the signal travels along with the mass being flung
through, there'll either be a lag, or you could tell how
much mass was coming by monitoring the apparent mass of the
exit point. Story possibilities...
Who is the author? Google was unhelpful. Got a link?
>> The time-rate difference between ends also screws up
>>momentum conservation depending where you observe from.
>
>
> For GR, you usually measure energy and momentum from an asymptotically
> flat background region of space-time to keep them conserved.
Sorry, I forgot; when you change frames you have to
transform velocities etc.
> It doesn't matter with what velocity the asymptotically flat frame is
> moving. There may be a possible issue with my understanding here, the
> issue being whether or not it is possible to create an asymptotically
> flat frame around a moving mass. Intuitively, this should be
> possible, but I can't confirm this rigorously. I've never seen an
> expression of the "gravitational field" <note the scare quotes> of a
> moving mass - unless you count the Aichelberg-Sexyl boost (but that
> only works in the limit of very high velocities).
"Asymptotocally flat" can exist over an arbitrarily small
region no matter where you are but I don't see how that
helps. If it doesn't include both ends of the WH
conservation looks impossible because the "change mass"
signal must be STL from inside and outside.
Mark L. Fergerson
pervect
wrote:
> So what happens to conservation of mass? Does the other
>end change in tandem? What mechanism communicates the signal
>to "change mass" between the ends of the WH? It better not
>be FTL either.
The way you get mass (energy) in general relativity is fairly similar
to the way you get charge for a charged argument, except that you have
added concerns about asymptotic flatness that make it a little more
complicated.
What you do to measure (and define the concept) of mass in GR is you
take a sphere surrounding the object whose mass you want to measure,
and you integrate the value of the normal field over the surface area
of the sphere. I.e. you use Gauss's law, with mass (or charge, if
it's an electirc field) = normal_component_of_force * area. In this
case I'm using the conventional notion of the gravitational field as a
force, not the geometric view.
The gravitational field lines of any body (like the electric field
lines) have to stay "hooked up". So when a body goes through a
wormhole, it "drags" its electric (and gravitational) field lines with
it.
So when the body passes through the wormhole, the mass of the wormhole
mouth, which is the gauss law intergal evaluated in a suitably flat
region of space-time around the wormhole does not change when the body
passes through. It stays constant.
In a very real sense, the body goes through the wormhole, but its mass
does not.
This is about as well as I can describe it, anyway.
> Who is the author? Google was unhelpful. Got a link?
The author of what?
For the time-rate of the moving wormhole issue, Forward (Timemaster)
and Kip Thorne (Einstein's outrageous legacy) come to mind.
For the mass of the wormhole issue, there is some discussion by Cramer
in his "Alternate Views" column I believe (which is on the WWW). There
is also something somewhere by Geoffrey Landis. Once upon a time I
saw a beautiful web page with a very nice diagram, but I have no idea
of what the URL was (I've looked for it in the past with no luck).
For a general discussion of mass/energy conservation in GR, there is
the sci.physics FAQ, and of course there is "Gravitation" by Misner,
Thorne, and Wheeler. I could get you specific pages of MTW and the
issue of mass with some effort - but unless you have or are going to
read the book there's no point, and one of its faults is that it's
very poorly indexed.
I'm not sure if the sci.physics.faq mentions Gauss's law or not, but
it does talk about asymptotic flatness and the other conditions you
need to be able to define a global energy in GR at all.
> "Asymptotocally flat" can exist over an arbitrarily small
>region no matter where you are but I don't see how that
>helps. If it doesn't include both ends of the WH
>conservation looks impossible because the "change mass"
>signal must be STL from inside and outside.
You need a sphere of space-time that's asymptotically flat to be able
to use Gauss's law, not just an arbitrarily small region.
Asymptotically flat in the sense required means no tidal forces - AND
no rotation. So you can't have asymptotically flat space-time in an
arbitrarily small region near a massive body in the sense I mean,
because there will be tidal forces present - the tidal forces are
equivalent to non-zero terms in the curvature tensor.
The geodesic deviation equation is what connects the abstract concept
of the curvature tensor to something that's basically physical and
understandable (the tidal forces) - in fact, you can write a
line-for-line equivalence between certain terms of the curvature
tensor, and tidal stretching force per unit distance by using the
geodesic deviation equation.
Mark Fergerson
> On Fri, 28 Nov 2003 12:18:07 -0700, Mark Fergerson <nu...@biz.ness>
> wrote:
>
>
>
>> So what happens to conservation of mass? Does the other
>>end change in tandem? What mechanism communicates the signal
>>to "change mass" between the ends of the WH? It better not
>>be FTL either.
>
>
> The way you get mass (energy) in general relativity is fairly similar
> to the way you get charge for a charged argument, except that you have
> added concerns about asymptotic flatness that make it a little more
> complicated.
>
> What you do to measure (and define the concept) of mass in GR is you
> take a sphere surrounding the object whose mass you want to measure,
> and you integrate the value of the normal field over the surface area
> of the sphere. I.e. you use Gauss's law, with mass (or charge, if
> it's an electirc field) = normal_component_of_force * area. In this
> case I'm using the conventional notion of the gravitational field as a
> force, not the geometric view.
Right, taking the volume containing both ends of the WH
conservation is obvious. My problem is that the ends are
separated by large (significant at c) distances which makes
it difficult for the WH to conserve much of anything except
internally.
Also the "lines of force" comparison sounds specious, but
what the hell.
> The gravitational field lines of any body (like the electric field
> lines) have to stay "hooked up". So when a body goes through a
> wormhole, it "drags" its electric (and gravitational) field lines with
> it.
So it comes out, and then what, its gravity field is
unidirectional towards the exit? Of course not.
If the WH tunnel is conductive, the problem goes away for
electric field lines; the WH just gains charge until the
object pops out. Now, can there be such a thing as a
"gravitational conductor"?
> So when the body passes through the wormhole, the mass of the wormhole
> mouth, which is the gauss law intergal evaluated in a suitably flat
> region of space-time around the wormhole does not change when the body
> passes through. It stays constant.
But it can't because the exit end "gains" the body's
mass. (It now sounds like you're taking only the volume
around the entrance.)
> In a very real sense, the body goes through the wormhole, but its mass
> does not.
>
> This is about as well as I can describe it, anyway.
Well, it sounds very bad. But then, I mentioned earlier
that wormholes bother me.
Anyway ISTM the only sensible answer is that the entire
wormhole gains the object's mass until it pops out. That
requires that gravitational waves propagate along the WH
ahead of the mass (possibly destabilizing the WH), but what
the hell. We still haven't established the internal travel
time for WHs. I think it has to be STL but the OP would like
instantaneity as seen by a traveler.
>> Who is the author? Google was unhelpful. Got a link?
>
>
> The author of what?
The "New Model Physics". I thought it was the OP's
invention but you seem familiar with it too.
> For the time-rate of the moving wormhole issue, Forward (Timemaster)
> and Kip Thorne (Einstein's outrageous legacy) come to mind.
Also Baxter and others that use WHs as time machines. At
least Niven never pulled this crap.
> For the mass of the wormhole issue, there is some discussion by Cramer
> in his "Alternate Views" column I believe (which is on the WWW). There
> is also something somewhere by Geoffrey Landis. Once upon a time I
> saw a beautiful web page with a very nice diagram, but I have no idea
> of what the URL was (I've looked for it in the past with no luck).
I'll look for that. Landis seems to know what he talks about.
>> "Asymptotocally flat" can exist over an arbitrarily small
>>region no matter where you are but I don't see how that
>>helps. If it doesn't include both ends of the WH
>>conservation looks impossible because the "change mass"
>>signal must be STL from inside and outside.
>
>
> You need a sphere of space-time that's asymptotically flat to be able
> to use Gauss's law, not just an arbitrarily small region.
>
> Asymptotically flat in the sense required means no tidal forces - AND
> no rotation. So you can't have asymptotically flat space-time in an
> arbitrarily small region near a massive body in the sense I mean,
> because there will be tidal forces present - the tidal forces are
> equivalent to non-zero terms in the curvature tensor.
I understood it to mean you could, if the region were
small enough. Besides, the infamous elevator _is_
arbitrarily small. In this case "arbitrarily" means you
can't see divergence or tidal forces. If you could, you
would know if you were immersed in anatural gravity field.
And if either end of the WH is moving, it'll look like
Terrell rotation to _some_ observer(s). Does Terrell
rotation induce frame-dragging?
Mark L. "I Hate Wormholes" Fergerson
pervect
wrote:
>
> Right, taking the volume containing both ends of the WH
>conservation is obvious. My problem is that the ends are
>separated by large (significant at c) distances which makes
>it difficult for the WH to conserve much of anything except
>internally.
You draw one volume around _each end) of the wormhole. The total
charge and mass inside that volume can't change in either volume.
>
> Also the "lines of force" comparison sounds specious, but
>what the hell.
It probably is a bit specious. Lines of force are exact for electric
charge. They also work well enough in reasonably flat space-time for
gravity, but they break down in curved space-time. However, once you
get out of the curved region of space-time, you can again apply
Gauss's law (and it serves as the ultimate definition of mass in
asymptotically flat space-times).
>> The gravitational field lines of any body (like the electric field
>> lines) have to stay "hooked up". So when a body goes through a
>> wormhole, it "drags" its electric (and gravitational) field lines with
>> it.
>
> So it comes out, and then what, its gravity field is
>unidirectional towards the exit? Of course not.
If we assume that the wormhole ends both had zero mass initially (a
bit unphysical, but easy to picture), when the object passes through,
you have a dipole field at the exit (the object exiting has a plus
mass, the wormhole has a negative mass). So the gravity field is not
unidirectional, but every field line leaving the mass/charge winds up
going through the wormhole.
The more real case involves the addition of a dipole field to a
background non-dipole field.
Looking at the entry wormhole - the field lines at the entry wormhole
all radiate out (or in) uniformly, just as if it had a charge. When
we apply Gauss's law, we in fact say that it does have a charge. Or a
mass, as the case may be.
>
> If the WH tunnel is conductive, the problem goes away for
>electric field lines; the WH just gains charge until the
>object pops out. Now, can there be such a thing as a
>"gravitational conductor"?
I don't know, but the idea might have some merit (much as the idea
that the event horizon of a black hole is conductive has merit, though
it's not actually a physical conductor).
Here is another puzzle that might shed some light. Consider a pair of
charged objects, Q1 and Q2. They experience a force between them.
Let us bring them close together. If Q1 and Q2 are of the same
charge, we have to do work to do this. This requires energy. Where
does this energy go? We say that it goes into the electric field.
Now consider a pair of massive objects M1 and M2. They experience an
attractive force. As we bring them together, they do work. How is
energy conserved?
We'd like to say that the energy is stored in the gravitational field.
Unfortunately, when we attempt to work out the details, we find out
that we can't make the bookkeeping work in the same simple manner that
we did for the electric field. We can't point to a specific region of
space and say "this region holds this much energy". At least not in
GR.
But we can still apply overall conservation laws. What it turns out
we *can't* do is get the total mass by integrating the energy density
over some volume. That approach doesn't work, you have to look at the
distant field.
Another way of saying this is that you can't get the total mass-energy
of a gravitationally bound system by just adding together the
associated masses (and the associated kinetic energies of each mass
divided by c^2). It won't work.
People tried for years to assign energy to specific regions of space
due to gravity in GR and failed. There's a lot of disucssion about
the futility of trying to do this in MTW, for instance.
>
>> So when the body passes through the wormhole, the mass of the wormhole
>> mouth, which is the gauss law intergal evaluated in a suitably flat
>> region of space-time around the wormhole does not change when the body
>> passes through. It stays constant.
>
> But it can't because the exit end "gains" the body's
>mass. (It now sounds like you're taking only the volume
>around the entrance.)
I am.
>
>> In a very real sense, the body goes through the wormhole, but its mass
>> does not.
>>
>> This is about as well as I can describe it, anyway.
>
> Well, it sounds very bad. But then, I mentioned earlier
>that wormholes bother me.
Re: what reference
> The "New Model Physics". I thought it was the OP's
>invention but you seem familiar with it too.
I'm just talking 70-odd year old conventional physics :-). NMP is
OP's invention AFAIK.
>
>> For the time-rate of the moving wormhole issue, Forward (Timemaster)
>> and Kip Thorne (Einstein's outrageous legacy) come to mind.
>
> Also Baxter and others that use WHs as time machines. At
>least Niven never pulled this crap.
>
>> For the mass of the wormhole issue, there is some discussion by Cramer
>> in his "Alternate Views" column I believe (which is on the WWW). There
>> is also something somewhere by Geoffrey Landis. Once upon a time I
>> saw a beautiful web page with a very nice diagram, but I have no idea
>> of what the URL was (I've looked for it in the past with no luck).
>
> I'll look for that. Landis seems to know what he talks about.
It's very brief, unfortunately, but you can find at least some
confirmation in the Cramer article I mentioned
http://www.npl.washington.edu/AV/altvw69.html
The relevant quote from the long article is:
"If a positive electric charge Q passes through a wormhole mouth, the
electric lines of force radiating away from the charge must thread
through the aperture of the wormhole. The net result is that the
entrance wormhole mouth has lines of force radiating away from it, and
the exit wormhole mouth has lines of force radiating toward it. In
effect, the entrance mouth has now been given a positive electric
charge Q, and the exit mouth acquires a corresponding negative charge
-Q. Similarly, if a mass M passes through a wormhole mouth, the
entrance mouth has its mass increased by M, and the exit mouth has its
mass reduced by an amount -M."
You can look for the Landis article too
>> Asymptotically flat in the sense required means no tidal forces - AND
>> no rotation. So you can't have asymptotically flat space-time in an
>> arbitrarily small region near a massive body in the sense I mean,
>> because there will be tidal forces present - the tidal forces are
>> equivalent to non-zero terms in the curvature tensor.
>
> I understood it to mean you could, if the region were
>small enough. Besides, the infamous elevator _is_
>arbitrarily small. In this case "arbitrarily" means you
>can't see divergence or tidal forces. If you could, you
>would know if you were immersed in anatural gravity field.
That's a problem of language useage and semantics. That's not the
sort of asymptotic flatness I mean. What you're saying is (I think)
that the geometry of space-time is locally Lorentzian. What I'm
saying is something quite different that's not related to that.
>
> And if either end of the WH is moving, it'll look like
>Terrell rotation to _some_ observer(s). Does Terrell
>rotation induce frame-dragging?
Terrell rotation is just an optical effect AFAIK. But a nearby
massive moving body does cause frame dragging according to some
calculations I did once upon a time.
Joseph Hertzlinger
The Nation will run an article proving that this means Capitalism Is Doomed.
> December, 2118: Kuiper Belt and Oort Cloud WH sources come online.
>
> January 2119: WH splitting is demonstrated.
>
> Suddenly the solar supply of WH has a sudden increase. Suddenly the
> "Star Bubble" collapses, making trillions of dollars evaporate in a single
> day. Happily the total economy is a hundred times bigger than it is today,
> so that is not as bad a hit as it would be today. Scholarly articles appear
> in the WSJ showing why this was inevitable.
The Nation will run an article proving that this means Capitalism Is Doomed.
Joseph Hertzlinger
wrote:
> It still bothers me that every other force we know of drops off as
> inverse sqaure or faster - this force doesn't fit that model. But I
> haven't been able to think of anything to back up my unease.
A system consisting of a charged particle and a magnetic monopole will
act as though it has an angular momentum. The magnitude of the angular
momentum will not depend on the distance between the two particles.
pervect
Is this a quantum effect? I drew some diagrams on the back of an
envelope for a classical monopole + charge, and there didn't seem to
me to be any reason for the system to have angular momentum.
Joseph Hertzlinger
wrote:
It's a classical effect. The Poynting vectors (redundant term, all
vectors Poynt) of the EM field will go around a line connecting the
two particles.
The effect of the angular momentum is that the system will act like a
gyroscope.
Ivana Marinkovic
<jcyclespersec...@nine.reticulatedcom.com> wrote:
~[...] The Poynting vectors (redundant term, all
~vectors Poynt)
Careful with them vectors. There's some Killing vectors out there.
--
Ivana Marinkovic |"After the first four years
Zagreb, Croatia |the dirt does not get any worse."
http://www.iridis.com/ivanam | --Quentin Crisp
pervect
wrote:
>On Wed, 03 Dec 2003 07:51:51 GMT, Joseph Hertzlinger
><jcyclespersec...@nine.reticulatedcom.com> wrote:
>
>
>~[...] The Poynting vectors (redundant term, all
>~vectors Poynt)
>
>Careful with them vectors. There's some Killing vectors out there.
LOL. OBSF "The McAndrew Chronicles" by Charles Sheffield.