Timeline for hypothetical criteria for non-paradox FTL
Current License: CC BY-SA 3.0
19 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 24, 2017 at 19:24 | comment | added | celtschk | For the second option (time travel in principle would be possible, but in practice not), you would simply not have the necessary technology to pull the wormhole trick. | |
| Feb 24, 2017 at 19:21 | comment | added | celtschk | @Obie2.0: The difference is the laws of physics. If you are not in the preferred frame of reference, you'd just find that certain FTL speeds cannot be achieved; that limit would be direction dependent and would directly allow you to determine the absolute speed relative to the preferred frame of reference. Wormhole physics, if that universe allows wormholes at all, would likely be very different from what General Relativity predicts; but that's no surprise, as General Relativity doesn't know a preferred frame of reference. | |
| Jan 7, 2017 at 1:56 | comment | added | Obie 2.0 | For example, let's say I am on Earth. I "teleport" to Vulcan through a wormhole. How does the existence of this "no time travel" frame prevent me from pulling the trick with accelerated wormhole mouths? | |
| Jan 7, 2017 at 1:44 | comment | added | Obie 2.0 | So, as I understand it, there is a preferred reference frame in which any travel can't go backwards in time. But how does this stop someone from going into their absolute past? In particular, what is the difference between a CMB frame where backwards travel is impossible, and our current CMB frame with unrestricted FTL added on? How does making backwards travel impossible in a CMB frame look different from a standard causality-violating FTL? | |
| Feb 20, 2015 at 22:04 | comment | added | celtschk | @smithkm: No, it is definitely not possible. But if you want to convince me otherwise, feel free to draw a spacetime diagram with your claimed causality violation. | |
| Feb 20, 2015 at 17:10 | comment | added | smithkm | The "preferred reference frame" makes causality breaking harder, but doesn't prevent them. Although making two FTL signals in different reference frames is the easiest way to use FTL to close a causality loop, it can be done with just one FTL signal and then another non-FTL signal as long as that second signal is fast enough to get back before the time gained runs out. So FTL jumping to a nearby star in CMB frame then transmitting a light speed signal back to Sol in Sol's reference frame could lead to that signal arriving before you left. | |
| Feb 19, 2015 at 16:49 | vote | accept | Foo Bar | ||
| Feb 19, 2015 at 16:48 | comment | added | Foo Bar | physics.stackexchange.com/questions/16596/… Lorentz Ether Theory is physically indistinguishable from relativity, except that a preferred reference frame exists. If you exit from normal space and travel through this otherwise-undetectable ether, causality-safe FTL can be internally consistent. | |
| Feb 19, 2015 at 14:59 | comment | added | user3652621 | @FooBar I can't say I am. I am not convinced that a "preferred" frame is possible or if so, that it can be successfully maintained. It is the best answer so far, however. I upvoted. | |
| Feb 19, 2015 at 13:03 | comment | added | Foo Bar | @SerbanTanasa As an FTL critic, are you satisfied with this answer? | |
| Feb 18, 2015 at 19:41 | comment | added | celtschk | @FooBar: Well, I would make a restriction: "To every FTL article unless there's a reason against it." A reason against it would be either that the question author explicitly states it (he might actually want to make time travel possible), or because he explicitly specifies a mechanism which doesn't have it (like the Alcubierre drive or the Star Trek warp drive — the latter is explicitly used for time travel in Star Trek IV), unless the author explicitly states he doesn't want time travel. | |
| Feb 18, 2015 at 19:30 | comment | added | Foo Bar | If I understand correctly, the existence of this preferred absolute reference frame doesn't even need to be detectable with current real-world technology. Relativity would still hold as an approximation of the universe, just not in certain cases beyond its parameters, the same way Newtonian mechanics was superseded by relativity. If so, can we assume that this preferred frame is appended to every FTL article here and be done with it? | |
| Feb 18, 2015 at 7:05 | comment | added | celtschk | You are in a different frame. But whatever enables FTL in that scenario still is in the very same frame as before. For example, just because you move relative to earth does not change the way earth moves. So anything dependent on the movement of earth does not care how fast you move. For example, despite relativity, all people will agree whether you are faster than sound, because the atmosphere determines a frame, and for the effects of being faster than sound, the velocity in that reference frame counts, and in none other. Think of the preferred reference frame as "cosmic atmosphere". | |
| Feb 18, 2015 at 2:26 | comment | added | user3652621 | but once you've accelerated, you're in a different frame, no? I just can't grok 'global preferred frame' in this context. | |
| Feb 17, 2015 at 23:40 | comment | added | celtschk | The point is that in that specific frame, you're not able to go back into time. You're of course seen as going FTL in other frames (indeed, in all other frames), and in other frame's coordinates you can even be seen to go backwards in time. The important part is that in this specific frame, you cannot go backwards in time, and that means you cannot get into your absolute past. And that's why you need a preferred frame: Because you cannot prevent going back in time in all frames, but in a preferred frame, you can. All paradoxes involve going FTL in two different frames. | |
| Feb 17, 2015 at 23:31 | comment | added | user3652621 | But if you're ftl relative to one frame, isn't there always at least one other frame you're also ftl relative to? | |
| Feb 17, 2015 at 23:27 | comment | added | celtschk | @SerbanTanasa: It means there is a global preferred frame of reference, relative to which your FTL drive works, and from which you cannot go into past. One example of such a frame would be the aether frame in Lorentz aether theory. | |
| Feb 17, 2015 at 23:24 | comment | added | user3652621 | What does 'restict ftl to a preferred frame' mean? Almost by definition, any ftl object has its own frame... | |
| Feb 17, 2015 at 23:04 | history | answered | celtschk | CC BY-SA 3.0 |