Hyperspace and time travel

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Hyperspace and time travel

Postby dirk_cjelli on Wed Aug 18, 2004 9:18 am

As I understand the teraport, it disassembles people into packets and transmits those packets through hyperspace via tiny wormholes. (Small wormholes are stable, large one's aren't... so the solution is to dis-assemble/ re-assemble).

Is it possible (in the schlockverse) for this to allow travel backwards in time?

Can this be harnessed as an infinite energy source? (importing superhot stellar matter into a reactor, for example)

Can the velocity with respect to the local frame be 'selected' and are the energy requirements subject to the laws of relativity?
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Re: Hyperspace and time travel

Postby IkkonoIshi on Wed Aug 18, 2004 11:37 am

dirk_cjelli wrote:Is it possible (in the schlockverse) for this to allow travel backwards in time?
No
dirk_cjelli wrote:Can this be harnessed as an infinite energy source? (importing superhot stellar matter into a reactor, for example)
Yes [edit]But it is more effecient to just do some direct matter to energy conversions like what all the ships already use.[/edit]
dirk_cjelli wrote:Can the velocity with respect to the local frame be 'selected' and are the energy requirements subject to the laws of relativity?
Yes
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Postby Jart Denko on Wed Aug 18, 2004 12:02 pm

I already explained how the whole wormhole/time-travel thing works. In the Schlockiverse, we haven't seen any <i>persistent</i> wormholes yet, so there's no plausible time travel scenario yet. My assumption is that holding a wormhole open requires an energy expenditure that would be considered massive, especially when the benefits of time travel are unproven.

Bear in mind, the method I know of doesn't allow for you to tavel back in time past the point that the time machine was constructed, because there's not a wormhole for you to go through at that point. But that's a detail.
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Postby ChowGuy on Wed Aug 18, 2004 4:36 pm

Well we know canonically that Kevyn was attempting to invent something (although we don't know what the principles were) which however only worked "after a fashion" so it's a fair bet that time travel isn't a common feature of the Schlockiverse, if it has even been developed at all.
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Postby n0z3k1ll3r on Thu Aug 19, 2004 2:23 am

I doubt it can be done. If anyone could do that sort of thing it would be the Fsherl'Ganni, and if they could do it they would have used it somehow to defeat Breya's fleet.
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Not too hard.

Postby GrantCMcCormick on Sun Sep 05, 2004 3:52 pm

Actually, given any form of FTL ability and a few constraints, it's not too hard.

    1) Whatever the laws of nature are, they are upwardly compatible with General Relativity. This is true of Brane Theory, String Theory, Loop Quantum Gravity, etc.

    2) There is no ether or the equivalent (i.e., no preferred reference frame).

    3) There are no deific constraints (i.e., Howard or God don't forbid it by fiat).

Given these, then, yes, time travel is possible and teraporting would allow it.

The key is that it tends to be resource intensive (read: expensive).

Velocities behave in Minkowski spacetime analogously to angles in Euclidean space. By having a realspace velocity relative to some worldline, your "past-future" hyperplane (your personal "now" space) tilts relative to that of the worldline.

Specifically, if you are moving that direction (say, towards the Galactic center, not that it matters) at, say, 0.1c, then your "now" is tilted by roughly one year of time for every ten lightyears of space, with the past behind you (appropriately enough), and the future in front of you.

So, if you jump 1000 LY directly aft (opposite the direction of your realspace motion) while moving at 0.1c relative to the galaxy as a whole, you will end up 100 years in the past of the point you jumped to. You would then have to kill the realspace velocity to stay in the past (this does not mean that if you don't kill it you'll pop back to the future or something -- it just means that any teraport jumps will have a time component to them in addition to the space component). Since this would involve a a net 0.2c realspace velocity change, that's why I call it resource intensive. But in the Schlockverse, it's actually fairly cheap.

Another way you can time travel with the Fsherl'Ganni-type permanent macro-wormholes is described in the late Robert Forward's novel Timemaster, where you move one end of the wormhole relative to the other, until a significant time-differential is built up between them. Even in the Schlockverse, this would be extremely resource intensive.

So, until recently, time travel in Schlock Mercenary was theoretically possible but technologically impossible. With teraporting, it is now both possible and feasible (so long as the three constraints above aren't violated). The first group to realize this will be at an immense advantage.

As to changing the past, some studies done in the 1990s and since say that what is known or is knowable about the past and the present have to be consistent (only those probability waves that reinforce themselves will be observed). Think of it as "You were always there in the past all along." Not really true, but that's what it amounts to.

So, if what we know about spacetime as of today continues to be true, and faster than light travel is possible, then time travel will be possible.

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Postby Alphaman_24 on Mon Sep 06, 2004 6:18 am

Velocities behave in Minkowski spacetime analogously to angles in Euclidean space. By having a realspace velocity relative to some worldline, your "past-future" hyperplane (your personal "now" space) tilts relative to that of the worldline.

Specifically, if you are moving that direction (say, towards the Galactic center, not that it matters) at, say, 0.1c, then your "now" is tilted by roughly one year of time for every ten lightyears of space, with the past behind you (appropriately enough), and the future in front of you.

So, if you jump 1000 LY directly aft (opposite the direction of your realspace motion) while moving at 0.1c relative to the galaxy as a whole, you will end up 100 years in the past of the point you jumped to.


Defining time in terms of space and velocity is fine and perfectly correct if there is no acceleration involved. The future is ahead of you because thats where you will be if you wait long enough, and importantly assuming nothing happens to you while travelling.

The nano-wormholes used for teraporting will apply gravitational forces to and object going through them which have exactly the same effect as an acceleration, in that it will distort your world line. Your future is now somewhere on the other end of the wormhole instead of ahead, and you will still only get there by waiting long enough.

The question becomes a matter of how the wormholes are generated. Since even Kevyn couldn't get a time machine working, I am going to take this as a sign that the other ends of the wormholes are positioned in time and space according to some set of laws (apparently not relativity) that maintains a self consistent time-frame.
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Well, maybe...

Postby GrantCMcCormick on Tue Sep 07, 2004 12:53 am

Alphaman_24 wrote:The nano-wormholes used for teraporting will apply gravitational forces to and object going through them which have exactly the same effect as an acceleration, in that it will distort your world line. Your future is now somewhere on the other end of the wormhole instead of ahead, and you will still only get there by waiting long enough.

The question becomes a matter of how the wormholes are generated. Since even Kevyn couldn't get a time machine working, I am going to take this as a sign that the other ends of the wormholes are positioned in time and space according to some set of laws (apparently not relativity) that maintains a self consistent time-frame.

The gravitational effects are why I specified General Relativity (not just Special), though Special Relativity will handle accelerations. I can even give you the formulae, if you like.

Your invocation of "positioned in time and space according to some set of laws (apparently not relativity) that maintains a self consistent time-frame" is implicitly stating that there is a perferred reference frame (i.e., no matter how your "Now" hyperplane is situated, when you teraport, you use the local Universal hyperplane). That eliminates time travel locally, but can lead to some paradoxes. How far does it extend unchanged? If it is the same over (say) a volume as small as our Milky Way galaxy, your non-time-traveling on THIS side of the galaxy would be time traveling on THAT side of the galaxy. And, more importantly, vice versa. What happens when you go a couple of hundred million light years away? Does the Universal hyperplane follow Hubble's Law?

Everything in the development of science from Aristotle to Hawking argues against a perferred reference frame. That doesn't mean it doesn't exist -- science conforms to the facts, in the long term, not the other way around.

But as of right now, I know which way I would bet.

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Re: Well, maybe...

Postby Alphaman_24 on Tue Sep 07, 2004 6:40 am

GrantCMcCormick wrote:Everything in the development of science from Aristotle to Hawking argues against a perferred reference frame.


I agree with that entirely... in our universe. However, the physics of the schlockiverse seem to have taken one or two hits in order to provide the much needed faster than light travel for the plot. The point about a reference frame applying within a certain limit is interesting, since I don't remember any mention of the teraport drive being used to move between galaxies. In fact, I don't remember any mention of range limits either which does imply (sort of) that some factor apart from simple distance is stopping intergalactic teraporting.

My suggestion is that galaxies contain some form of medium (not an ether, just some kind of matter) that the teraport, through some unknown process, uses to create and position the other ends of the nano-wormholes. This would definitely put limits on the destination end, although it still has some major difficulties with the basic idea of transmitting information faster than light.
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Re: Well, maybe...

Postby GrantCMcCormick on Tue Sep 07, 2004 10:50 pm

Alphaman_24 wrote:However, the physics of the schlockiverse seem to have taken one or two hits in order to provide the much needed faster than light travel for the plot. The point about a reference frame applying within a certain limit is interesting, since I don't remember any mention of the teraport drive being used to move between galaxies. In fact, I don't remember any mention of range limits either which does imply (sort of) that some factor apart from simple distance is stopping intergalactic teraporting.

My suggestion is that galaxies contain some form of medium (not an ether, just some kind of matter) that the teraport, through some unknown process, uses to create and position the other ends of the nano-wormholes. This would definitely put limits on the destination end, although it still has some major difficulties with the basic idea of transmitting information faster than light.

That, per se, would not this from being used for de facto time travel within a galaxy. That medium existed ten years ago, too. The whole point comes down to the fact that, by virtue of your realspace velocity, your "right now, this very instant" of a point 100 LY away corresponds to someone else's (say, Earth's) 100+ LY away, 10 years ago point.

The only way out, really, is to say that all teraportings happens in the "now" hyperplane of some (given) reference frame, likliest the center-of-mass frame of the galaxy (or the time travel would have already been noticed!). But this leads to problems with other galaxies.

Since mass in far extragalactic space is moving more-and-more rapidly away from Earth (the expansion of the universe), this means there cannot be any sort of universal "now" hyperplane.

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Re: Well, maybe...

Postby Sidhekin on Tue Sep 07, 2004 11:39 pm

GrantCMcCormick wrote:Since mass in far extragalactic space is moving more-and-more rapidly away from Earth (the expansion of the universe), this means there cannot be any sort of universal "now" hyperplane.

Oh yes there can.

Just define Universal Time Preordained as "local time since Big Bang", and you have it.

Of course, this is a "hyperplane" only in certain mappings from time-space continuum to n-space, but hey ... once you start going on about general relativity, that is a given.
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Re: Not too hard.

Postby Jart Denko on Wed Sep 08, 2004 5:20 am

GrantCMcCormick wrote:Another way you can time travel with the Fsherl'Ganni-type permanent macro-wormholes is described in the late Robert Forward's novel Timemaster, where you move one end of the wormhole relative to the other, until a significant time-differential is built up between them. Even in the Schlockverse, this would be extremely resource intensive.


A minor quibble - the Fsherl'Ganni wormholes aren't permanent, as far as I can tell.
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That was now and this is then.

Postby GrantCMcCormick on Thu Sep 09, 2004 12:49 am

Sidhekin wrote:
GrantCMcCormick wrote:Since mass in far extragalactic space is moving more-and-more rapidly away from Earth (the expansion of the universe), this means there cannot be any sort of universal "now" hyperplane.

Oh yes there can.

Just define Universal Time Preordained as "local time since Big Bang", and you have it.

Of course, this is a "hyperplane" only in certain mappings from time-space continuum to n-space, but hey ... once you start going on about general relativity, that is a given.

This is one of those "Yes, but... Not really." times.

If spacetime really is truly Euclidean 'flat' (close enough for jazz), and the expansion were isotropically uniform (here the deviations are a little more significant), this would work -- for timekeeping purposes. We would all agree on such statements as "At about 13,700,000,000 years after the big bang, the cosmic temperature was 2.73K." In that sense, yes, we can establish a universal clock.

But...

That's not what I mean by a "Universal "now" hyperplane". Under Newtonian kinematics, all observers at a given instant share the same space. If all of our clocks are properly synchronized, then at any given instant (say 2004-09-10 22:00:00.00 MDT), the subset of spacetime where all possible clocks could read this value would be a flat three-dimensional cross-section of a four-dimentional Minkowski spacetime -- i.e., it would be a true 3D hyperplane. The motions of the various observers and clocks would not matter -- motion under Newtonian kinematics does not affect time.

For simplicity, I am going to argue using Special (rather than General) Relativity for this next part. It would not change the overall nature of the arguement (since the large-scale structure of spacetime seems to be nearly flat). Under Relativity, motion does affect time. For example, if you see a clock moving with respect to you, it appears to be running slow. But that is not the only effect that motion has on time.

Let us define a "General Consensous" frame of reference, defined as (say) "the average center-of-mass frame of reference for all stars withing one kiloparsec of Sol" (other definitions are possible, but this will do for now). Most mass near us is either in this frame of reference, or moving very slowly relative to it. For this frame of reference, there is a well-defined "now" hyperplane, that just about everyone around can agree on.

Now, let's introduce a spaceship moving at 0.1c due East. What hapens is that its "now" hyperplane is "tilted" relative to the General Consensus, so what it thinks is exactly 100 LY behind it "now", the Consensus would find to be 100.504 LY to the west and 10.0504 years in the past. So if the ship teraported "instantly" 100 LY due west, the point at which it would find itself would be about 10 years in the past of the Consensus. If it then changed its velocity to lose the 0.1c relative motion (i.e., accelerated westward) until it was at rest relative to the Concensus, and then teraported 100.504 LY eastward, it would find itself at the same spacial location, but still approximately 10 years in the past.

Since all galaxies outside the Local Group have significant velocities relative to ours, they all have "now" hyperplanes that are tilted in time relative to ours. This is what I meant when I said that there was no universal "now" hyperplane. One that works for the Milky Way would be all wrong for M51, and really bad for the nearest quasar.

With typical stellar proper motion in our neighborhood (30 to 300 km/s [i.e., 0.0001c to 0.001c]), and with typical jumps on the order of 100 LY, the maximum temporal displacement (past or future) would be on the order of a month, and more usually just a few days, plus or minus.

And, as I have said before, all this depends on is (1) the universe is fully upward compatible from General Relativity, and (2) some sort of FTL travel is possible. (The "fully upward compatible" would rule out a "special" perfered frame of reference for FTL, as well any deific interference.)

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Re: That was now and this is then.

Postby Sidhekin on Thu Sep 09, 2004 1:16 am

GrantCMcCormick wrote:
Sidhekin wrote:
GrantCMcCormick wrote:Since mass in far extragalactic space is moving more-and-more rapidly away from Earth (the expansion of the universe), this means there cannot be any sort of universal "now" hyperplane.

Oh yes there can.

Just define Universal Time Preordained as "local time since Big Bang", and you have it.

Of course, this is a "hyperplane" only in certain mappings from time-space continuum to n-space, but hey ... once you start going on about general relativity, that is a given.

This is one of those "Yes, but... Not really." times.

Define "really". :-)

We would all agree on such statements as "At about 13,700,000,000 years after the big bang, the cosmic temperature was 2.73K." In that sense, yes, we can establish a universal clock.

Which is all I was saying.

That's not what I mean by a "Universal "now" hyperplane".

Hey, I address what you say, it is not my fault if you don't mean it. ;-)

Under Newtonian kinematics, all observers at a given instant share the same space.

Newtonian kinematics do not apply if you assume the UTP.

Let us define a "General Consensous" frame of reference, defined as (say) "the average center-of-mass frame of reference for all stars withing one kiloparsec of Sol" (other definitions are possible, but this will do for now).

There is no way the "now" frame of reference so defined can correspond to the "now" of the UTP. So, anything you argue from this, does not apply to the UTP.

Since all galaxies outside the Local Group have significant velocities relative to ours, they all have "now" hyperplanes that are tilted in time relative to ours. This is what I meant when I said that there was no universal "now" hyperplane.

Correction: there is no universal "now" hyperplane so defined.

The UTP is defined quite differently, and does hold up for quasars as well.

And, as I have said before, all this depends on is (1) the universe is fully upward compatible from General Relativity, and (2) some sort of FTL travel is possible. (The "fully upward compatible" would rule out a "special" perfered frame of reference for FTL, as well any deific interference.)

Well, the problem is that we have no mechanism for FTL. Even wormholes are not FTL, they just bring places closer together than they seem to be ...
and even that only if the wormholes are created and then brought "apart" at speeds lower than light.

When reading stories requiring FTL, suspension of disbelief is recommended. :-)
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Definitions.

Postby GrantCMcCormick on Thu Sep 09, 2004 2:10 am

Definitions:

Hyperplane: a 3D cross-section of a 4D spacetime. Approximately (for visualization purposes only!), a frozen "instant" in space.

A "now" hyperplane: a hyperplane that a given physically-realizable frame of reference would consider isochronous with the designated instant -- a given observer's "right now", throughout spacetime.

Your UTP works for observers going with the flow -- at rest with the local co-moving portion of the Hubble expansion. The 'General Consensus' frame would be UTP-compliant anywhere in this portion of the galaxy. It would not work for observers moving with significant velocity with respect to the local Hubble expansion. So the UTP is not universal (good for all observers) even if it can be defined for most locations in the universe (so long as you restrict reference frames).

My definition of FTL is being able to travel a geodesic distance d in time t less than d/c. The details (wormhole, hyperspace, tachyons, etc.) do not matter, so long as t < d/c.

The reason I've been talking hyperplanes as I've defined here (particularly "now" hyperplanes) is because they are what our FTL will work in. With teraporting, youy will teraport into some other point of your "now" hyperplane. It doesn't worry or care about UTPs or UTP values. It just jumps. Now.

One man's now is another man's then.

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Re: Definitions.

Postby Sidhekin on Thu Sep 09, 2004 2:34 am

GrantCMcCormick wrote:Your UTP works for observers going with the flow -- at rest with the local co-moving portion of the Hubble expansion. The 'General Consensus' frame would be UTP-compliant anywhere in this portion of the galaxy. It would not work for observers moving with significant velocity with respect to the local Hubble expansion.

Why not?

Sure, time dilation would occur, but that is just one of the givens of UTP. You can work with it.

In what manner does it "not work"?

The reason I've been talking hyperplanes as I've defined here (particularly "now" hyperplanes) is because they are what our FTL will work in.

By definition? ;-)

Eh, if FTL works as observed from one reference frame, it should work as observed from any reference frame. If your "hyperplanes" permit FTL, so does any other frame of reference. They all agree on that.

What they do not agree on though, is whether or not a specific instance of FTL arrives "before" departure.

With teraporting, youy will teraport into some other point of your "now" hyperplane. It doesn't worry or care about UTPs or UTP values. It just jumps. Now.

Okay, that was news to me. References? (To the link between teraport and hyperplanes.)

Anyway, if this is how teraporting works, then it should allow time travel, unless there is such a rule as "you cannot teraport in the direction you are travelling, relative to the background radiation" or some similar fiat.

Update: Well, actually that depends on what happens when the mass that is teraported is so big that it has an impact on the consensus rest frame.
I think I shall leave that in the blue, as it were, until I feel the need to go math-crazy on this problem. (i.e. forever, most likely)
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Re: Definitions.

Postby GrantCMcCormick on Thu Sep 09, 2004 10:42 am

Sidhekin wrote:
GrantCMcCormick wrote:Your UTP works for observers going with the flow -- at rest with the local co-moving portion of the Hubble expansion. The 'General Consensus' frame would be UTP-compliant anywhere in this portion of the galaxy. It would not work for observers moving with significant velocity with respect to the local Hubble expansion.

Why not?

Sure, time dilation would occur, but that is just one of the givens of UTP. You can work with it.

In what manner does it "not work"?


It does not work because it leads to inconsistencies. Because your UTP is defined as "local time since Big Bang", an observer with significant velocity would have a significantly different UTP value at a given point in space and time than would a co-moving (with the Hubble expansion) observer.

This doesn't bother me, because I don't care about this UTP. But if you don't defend it, it becomes nothing more than a synonym for "age" for each particular particle out there.

Sidhekin wrote:
GrantCMcCormick wrote:The reason I've been talking hyperplanes as I've defined here (particularly "now" hyperplanes) is because they are what our FTL will work in.

By definition? ;-)

Yes, by definition. Remember, this is based on the assumption that General Relativity (or a replacement theory that is fully upward compatible) applies. So, if you have an instantaneous drive, such as the teraport, the "instant" that it transports you in has to be your instant, not somebody else's. If they teraport, they will do so in their instant.

Sidhekin wrote:Eh, if FTL works as observed from one reference frame, it should work as observed from any reference frame. If your "hyperplanes" permit FTL, so does any other frame of reference. They all agree on that.

Totally true. I can teraport, in my frame of reference. And you can teraport, in your frame of reference. Neither is better or truer than the other. And everybody agrees on the physics.

Sidhekin wrote:What they do not agree on though, is whether or not a specific instance of FTL arrives "before" departure.

True. My "I got there in zero time" (i.e., instantaneous) is the other guy's "You got there ten years ago."

Sidhekin wrote:
GrantCMcCormick wrote:With teraporting, youy will teraport into some other point of your "now" hyperplane. It doesn't worry or care about UTPs or UTP values. It just jumps. Now.

Okay, that was news to me. References? (To the link between teraport and hyperplanes.)


I am assuming that the teraport is an instantaneous (or near-instantaneous) teleportation system. All that really matters, however, is that it is FTL. Then, because of the assumption that General Relativity (or a replacement theory that is fully upward compatible) applies, it follows that the teraport has to be to some point in your "now" hyperplane -- that is just another way of saying that I just made an instantaneous jump.

Sidhekin wrote:Anyway, if this is how teraporting works, then it should allow time travel, unless there is such a rule as "you cannot teraport in the direction you are travelling, relative to the background radiation" or some similar fiat.

That rule would violate General Relativity big time, so, yeah, it would keep time travel from happening. Fundamentally, it is another variation of the perferred reference plane fiat.

Sidhekin wrote:Update: Well, actually that depends on what happens when the mass that is teraported is so big that it has an impact on the consensus rest frame.
I think I shall leave that in the blue, as it were, until I feel the need to go math-crazy on this problem. (i.e. forever, most likely)

Don't confuse the reference frame (the particular coordinate set adopted) with the spacetime that it is embedded in. A sufficient mass could curdle or collapse the spacetime, but never touch the reference frame (which is, after all, a mathemetical and observational construct).

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Postby Howard Tayler on Thu Sep 09, 2004 11:32 am

Okay, you guys. Impress me:

Show me a violation of causality with the teraport, using characters from Schlock Mercenary. Tell me a story in which the lack of a Universal Reference Frame has a character meeting himself, or making a killing at the horse races, or preventing his own death.

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Postby Tegeran on Thu Sep 09, 2004 1:08 pm

Howard Tayler wrote:Show me a violation of causality with the teraport, using characters from Schlock Mercenary. Tell me a story in which the lack of a Universal Reference Frame has a character meeting himself, or making a killing at the horse races, or preventing his own death.


I don't believe that's possible, and that belief is backed up by yet another belief: That you wouldn't have created a universe where it was possible.

Note: I am not a physicist. I don't even play one on TV. Nor is my grasp of causality or all the other factors involved necessarily complete or correct. But even so, I say this:

Under Schlock physics, with "instant" propagation of gravity, I can't find a causality violation involving the teraport.

Kevyn, standing on the Sarasota, sends a message to Tagon, on the Serial Peacemaker halfway across the galaxy, through the Hypernet, asking that he teraport to the Sarasota. Tagon teraports the SP to the Sarasota's position.

From both frames of reference, the absolute smallest amount of time that could pass between the transmission of the message and the action it caused is 5.391 * 10<sup>-44</sup> seconds (one unit of "Planck time"), which is non-zero, and definitely non-negative (and the amount of time would never be that small in practice anyway, and you may not even be able to get it that small in any amount of bizarre theory).

Anyone watching from a third frame of reference and monitoring only light, not gravity, deserves whatever eye-crossing numbers they get. These same people would probably try to find a supersonic jet's position by the sound it makes.
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Re: Definitions.

Postby Sidhekin on Thu Sep 09, 2004 2:42 pm

GrantCMcCormick wrote:
Sidhekin wrote:In what manner does it "not work"?


It does not work because it leads to inconsistencies. Because your UTP is defined as "local time since Big Bang", an observer with significant velocity would have a significantly different UTP value at a given point in space and time than would a co-moving (with the Hubble expansion) observer.


No, it does not. Velocity has no impact on location, so velocity matters not.

I chose to leave "local time since big bang" rather fuzzy, but that seems to have been a bad choice. A more precise definition of UTP would be "maximal timeline length from big bang to here-and-now". (Thus, for every here-and-now, there is precisely one UTP value -- independent of velocity.)

Sidhekin wrote:
GrantCMcCormick wrote:With teraporting, youy will teraport into some other point of your "now" hyperplane. It doesn't worry or care about UTPs or UTP values. It just jumps. Now.

Okay, that was news to me. References? (To the link between teraport and hyperplanes.)


I am assuming that the teraport is an instantaneous (or near-instantaneous) teleportation system.

Sure, it is instantaneous in some reference frame. But how do you get from there to "instantaneous in the 'now' hyperplane"?

Or am I misreading you? Would you allow that the assumption of instantaneous teleportation system is fulfilled by a system that takes you to a place with the same UTP?


Sidhekin wrote:Update: Well, actually that depends on what happens when the mass that is teraported is so big that it has an impact on the consensus rest frame.
I think I shall leave that in the blue, as it were, until I feel the need to go math-crazy on this problem. (i.e. forever, most likely)

Don't confuse the reference frame (the particular coordinate set adopted) with the spacetime that it is embedded in.

No worries: I don't.

Now don't you confuse any old reference frame with a rest frame. I am speaking of the reference frame in which the center of mass is at rest. If the mass teraported is significant, the center of mass moves ... :-)

And no, I still don't feel the urge to go math-crazy on that one. :-)
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Postby GrantCMcCormick on Thu Sep 09, 2004 5:26 pm

Tegeran wrote:
Howard Tayler wrote:Show me a violation of causality with the teraport, using characters from Schlock Mercenary. Tell me a story in which the lack of a Universal Reference Frame has a character meeting himself, or making a killing at the horse races, or preventing his own death.


I don't believe that's possible, and that belief is backed up by yet another belief: That you wouldn't have created a universe where it was possible.

Note: I am not a physicist. I don't even play one on TV. Nor is my grasp of causality or all the other factors involved necessarily complete or correct. But even so, I say this:

Under Schlock physics, with "instant" propagation of gravity, I can't find a causality violation involving the teraport.

Kevyn, standing on the Sarasota, sends a message to Tagon, on the Serial Peacemaker halfway across the galaxy, through the Hypernet, asking that he teraport to the Sarasota. Tagon teraports the SP to the Sarasota's position.

From both frames of reference, the absolute smallest amount of time that could pass between the transmission of the message and the action it caused is 5.391 * 10<sup>-44</sup> seconds (one unit of "Planck time"), which is non-zero, and definitely non-negative (and the amount of time would never be that small in practice anyway, and you may not even be able to get it that small in any amount of bizarre theory).

Anyone watching from a third frame of reference and monitoring only light, not gravity, deserves whatever eye-crossing numbers they get. These same people would probably try to find a supersonic jet's position by the sound it makes.

My argument is that this may be an unrecognized capability withing the Schlock universe. Or it may be a chimera.

Specifically, if the following two assumptions are true, then some form of time travel is possible:
    First, that some form of faster-than-light transport is possible. This is obviously a given within the Schlock universe. For purposes of my debate with Sidhekin, I have been assuming it is instantaneous (it makes the arguement easier), but all that is required is some form of FTL.

    Second, that whatever laws of physics that apply to this FTL are fully upwardly compatible with General Relativity. Specifically, that the laws of physics impose no "special" or "perferred" reference frame for anything that goes on, including FTL travel.

If these two strictures are true, then time travel is possible. Alternatively, if time travel is not possible, the one or the other (or both) must be false.

For example, if Howard states that there is a reference frame such that all wormhole travel, including teraporting, happens relative to that particular reference frame, then there would be no time travel. End of story.

The reason that time travel is possible if these two things are true has to do with the nature of spacetime. Under Newtonian physics (which assumes an infinite speed of light), all observers, no matter what their velocity, agree on what "now" means, and under what circumstances two events are simultaneous. With a finite speed of light under Relativity, this isn't true anymore.

In spacetime, velocities act something like angles in Euclidian geometry (specifically, like imaginary angles, so that where you would use the [trigonometric] sin(x), cos(x), and tan(x) functions in working with angles in Geometry, you would use the [hyperbolic] sinh(x), cosh(x), and tanh(x) functions in working with velocities in Relativity).

Without going into more detail than I can provide here while on break, if two observers are moving with respect to one another, they will disagree as to what events are past, what events are simultaneous, and what events are future. If one of them teraports relative to her/his idea of simultaneous, she/he can end up in the other's past. And by changing velocities and teraporting again, end up in her/his own past.

But, to repeat myself: All Howard has to do is stipulate that the current theories of spacetime, and the evidence that supports them, are not upwardly compatible from General Relativity, in that they have a perferred refernece frame (in which teraporting and other FTL phenomena happen), and time travel would be impossible.

In a real sense, what I am (and have been) saying, is that if FTL were discovered today, based on what we know today, then time travel would be theoretically possible.

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Postby Howard Tayler on Thu Sep 09, 2004 7:58 pm

I wasn't asking the question in a "so there" sort of way. I wanted to see if there were story possibilities I hadn't been exploring, or, worse still, huge inconsistencies in the Schlockiverse that needed to be plugged.

Incidentally, gravity in the Schlockiverse does NOT propagate instantaneously. Gravity IS, however, detectable by popping a wormhole open (like the teraport does) and seeing if it jiggles. It's a little like dropping a plum line down a shaft, and observing your end of the line. In this case the plum line DOES transmit information instantaneously, although the bandwidth is mighty low.

I'm pretty sure this means that the "fabric" through which teraports and the Hypernet pass information is the Universal Frame of Reference we need to avoid violating causality when teraporting.

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Postby Tegeran on Thu Sep 09, 2004 8:23 pm

Howard Tayler wrote:Incidentally, gravity in the Schlockiverse does NOT propagate instantaneously. Gravity IS, however, detectable by popping a wormhole open (like the teraport does) and seeing if it jiggles. It's a little like dropping a plum line down a shaft, and observing your end of the line. In this case the plum line DOES transmit information instantaneously, although the bandwidth is mighty low.


Ahh! Gotcha. Things make a bit more sense now. I'd thought you said it did a while back, but that might have either been some sort of hypothetical discussion, or me misreading an explanation of the above.

Howard Tayler wrote:I'm pretty sure this means that the "fabric" through which teraports and the Hypernet pass information is the Universal Frame of Reference we need to avoid violating causality when teraporting.


This is what I think, too. I basically don't see how you can violate causality simply by moving from one place to another faster than light can, if information can be transmitted instantly between arbitrary points. (But again, I'm definitely no physicist.)
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Postby GrantCMcCormick on Thu Sep 09, 2004 10:01 pm

Howard Tayler wrote:I wasn't asking the question in a "so there" sort of way. I wanted to see if there were story possibilities I hadn't been exploring, or, worse still, huge inconsistencies in the Schlockiverse that needed to be plugged.

Incidentally, gravity in the Schlockiverse does NOT propagate instantaneously. Gravity IS, however, detectable by popping a wormhole open (like the teraport does) and seeing if it jiggles. It's a little like dropping a plum line down a shaft, and observing your end of the line. In this case the plum line DOES transmit information instantaneously, although the bandwidth is mighty low.

I'm pretty sure this means that the "fabric" through which teraports and the Hypernet pass information is the Universal Frame of Reference we need to avoid violating causality when teraporting.

--Howard

Current theory (such as it is) is that events have to be consistent both in the past and in the present. So, the "instant" (and please don't ask me to define this here!) you went back in time, the universe might rearrange itself drasticly, even to the past of when you arrived. But, once rearranged, it would stay rearranged in that way, and as far as the universe was concerned, had always been that way. So as far as anyone could remember, any evidence, any history, it had always been that way, too.

It's actually the worst combination of can/cannot change the past. You can't avoid changing it, but at the same time you cannot do so in any useful or knowing way. Because it all involves quantum probability wave functions, and which ones are reinforced via the time loop, and which ones are dampened by the same, there is no way to even predict what the results would be, just that they would be consistent. It is not impossible that they would have you consistently gone.

For a cautionary tale on the subject, see the 1970s Larry Niven's story, "Rotating Cylinders and the Possibility of Global Causality Violations", which was based on the Frank Tipler article of the same title.

Best not to allow it...

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Postby Howard Tayler on Thu Sep 09, 2004 10:29 pm

Tegeran wrote:
Howard Tayler wrote:Incidentally, gravity in the Schlockiverse does NOT propagate instantaneously. Gravity IS, however, detectable by popping a wormhole open (like the teraport does) and seeing if it jiggles. It's a little like dropping a plum line down a shaft, and observing your end of the line. In this case the plum line DOES transmit information instantaneously, although the bandwidth is mighty low.


Ahh! Gotcha. Things make a bit more sense now. I'd thought you said it did a while back, but that might have either been some sort of hypothetical discussion, or me misreading an explanation of the above.


I probably DID say that. I mean, I'm making most of this up as I go along. It's only a comic strip, after all.

The wormhole/plumline analogy, though... that's technobabble at its finest, and I'm particularly pleased with it.

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