YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More?

[Kraven Kor]

http://www.scientificamerican.com/article.cfm?id=splitting-time-from-space

 

Interesting, and it isn't immediately debunked by the very article presenting it.

 

What might this mean for the possibility of FTL Travel, or at least for those of us who read, write, or play in Science Fiction settings with FTL Travel?

[Nyrath]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Unfortunately, my limited understanding of Hořava’s theory says that it still does not allow FTL travel. But it does have some implications about dark matter and the big bang theory.

[Kraven Kor]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Well, wouldn't the whole "FTL = Time Travel" thing change due to this? I thought the whole reasoning behind that was the interrelation of space and time.

[dmjalund]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

** Dalek voice ** "Exterminate all oblate spheroids"

[McCoy]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Well' date=' wouldn't the whole "FTL = Time Travel" thing change due to this? I thought the whole reasoning behind that was the interrelation of space and time.[/quote']

Apparently not.

Gia Dvali, a quantum gravity expert at CERN, remains cautious. A few years ago he tried a similar trick, breaking apart space and time in an attempt to explain dark energy. But he abandoned his model because it allowed information to be communicated faster than the speed of light.

[Kristopher]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Apparently not.

Gia Dvali, a quantum gravity expert at CERN, remains cautious. A few years ago he tried a similar trick, breaking apart space and time in an attempt to explain dark energy. But he abandoned his model because it allowed information to be communicated faster than the speed of light.

 

Which is an unfortunate example of reasoning from conclusion. If it's possible for infomation to travel faster than light, then it is.

[Blue Jogger]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

To me, it screams stasis fields. Pump enough energy to separate time and space and now your object is neatly suspended in timeless space.

 

FTL = time travel is because if you perceive events backwards than since your reference point is as valid as anyone else's, you are effectively going backwards in time. What the theory may allow, possibly, is the ability to say, time is screwed up (because I'm in a time machine) and it may appear that I can go back and kill my grandfather before my dad was born, but in the correct universal reference frame, my grandfather must have lived.

[Yansuf]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Off hand, (it has been MANY years since I studied relativity [heck, it was a previous millenium]) I do not see how getting from Sol to Alpha Centauri instantly via a worm hole (or jump drive) violates causality.

The arguments that FTL=time travel all seem to involve MOVING at FTL speed (and the resulting frames of reference); how does a worm hole with instantaneous travel equal (retrograde) time travel?

[Cancer]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

First I've heard of this idea, but I am not a theorist or relativist. I tend not to work out in the theoretical boondocks.

 

It'll be interesting to see how PSR B1913+16 ... the binary pulsar, whose orbital change matches very well the predictions of energy loss by gravity waves which is predicted by general relativity ... fits into this idea.

[Nyrath]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Off hand' date=' (it has been MANY years since I studied relativity [heck, it was a previous millenium']) I do not see how getting from Sol to Alpha Centauri instantly via a worm hole (or jump drive) violates causality.

The arguments that FTL=time travel all seem to involve MOVING at FTL speed (and the resulting frames of reference); how does a worm hole with instantaneous travel equal (retrograde) time travel?

 

Well, the arguments I've seen for FTL=time travel seem to hing on a "signal" from point A being received at point B faster than a ray of light could deliver it (i.e., "outside of the light cone").

For purposes of the argument it does not matter if the signal actually traveled through all the points between A and B or if it used a wormhole as a short-cut.

[Litvyak]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

FTL = time travel is because if you perceive events backwards than since your reference point is as valid as anyone else's, you are effectively going backwards in time.

 

Perception does not automatically equal time travel. Imagine moving away from the Earth at a speed faster than light, if you look behind you will perceive time back on Earth as moving in reverse. Is this because you're actually travelling back in time, or simply because you're outrunning the light from Earth and seeing older and older images? In the latter case your relationship in time relative to the Earth hasn't actually changed, but it would appear that it has.

[Cancer]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Perception does not automatically equal time travel. Imagine moving away from the Earth at a speed faster than light' date=' if you look behind you will perceive time back on Earth as moving in reverse. Is this because you're actually travelling back in time, or simply because you're outrunning the light from Earth and seeing older and older images? In the latter case your relationship in time relative to the Earth hasn't actually changed, but it would appear that it has.[/quote']

 

But if you emit light back toward Earth from a point on your outbound leg, then it is possible that the light thus emitted will arrive on Earth before the emission of the light created when your FTL trip began. If your FTL launcher was triggered by a photocell, then it could easily be that you have a gross causality violation, that the light emitted after the FTL probe was launched caused the launch itself, i.e., that the cause of an event lies later in time than the event itself.

[Litvyak]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

But if you emit light back toward Earth from a point on your outbound leg' date=' then it is possible that the light thus emitted will arrive on Earth before the emission of the light created when your FTL trip began. If your FTL launcher was triggered by a photocell, then it could easily be that you have a gross causality violation, that the light emitted after the FTL probe was launched caused the launch itself, i.e., that the cause of an event lies later in time than the event itself.[/quote']

 

I'm not following... if you emit light back towards Earth it will travel at the speed of light and I'm not seeing how it's possible for it arrive before you left. This is of course based on the theory that time dilation and time travel are an optical illusion created by rapid movement through space and that time is actually absolute for all observers.

[Nyrath]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

I'm not following... if you emit light back towards Earth it will travel at the speed of light and I'm not seeing how it's possible for it arrive before you left. This is of course based on the theory that time dilation and time travel are an optical illusion created by rapid movement through space and that time is actually absolute for all observers.

 

http://sheol.org/throopw/tachyon-pistols.html

http://www.theculture.org/rich/sharpblue/archives/000089.html

[Litvyak]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

http://sheol.org/throopw/tachyon-pistols.html

http://www.theculture.org/rich/sharpblue/archives/000089.html

 

 

I haven't read the second link yet, but I'm familiar with the Tachyon Pistols argument. When you apply the theory that time dilation is an optical illusion and time is absolute for all observers, there are no real causality issues, though there might be perceived ones.

[Nyrath]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

I haven't read the second link yet' date=' but I'm familiar with the Tachyon Pistols argument. When you apply the theory that time dilation is an optical illusion and time is absolute for all observers, there are no [i']real[/i] causality issues, though there might be perceived ones.

 

Well, I was under the impression that according to Special Relativity, time is not absolute for all observers. The speed of light is.

[austenandrews]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

The article in the OP is talking about extremely high energies. As it says, the theory won't be accepted until/unless it matches current observed data, which includes time dilation.

[Litvyak]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Well' date=' I was under the impression that according to Special Relativity, time is [b']not[/b] absolute for all observers. The speed of light is.

 

Special Relativity basically says that perception of time isn't absolute for all observers. The question is whether is that perception is reality, or just an optical illusion. If you believe that perception is reality, then there's all kinds of causality issues with FTL travel. If you believe that perception is an optical illusion than there's no more causality issues with FTL travel than with supersonic travel.

 

Which is correct? Who knows... I'm just a gamer and sci-fi enthusiast, so I use whatever theory fits the effects I want from a setting.

[Kraven Kor]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

The article in the OP is talking about extremely high energies. As it says' date=' the theory won't be accepted until/unless it matches current observed data, which includes time dilation.[/quote']

 

Have we actually observed time dilation though? I thought that was still fairly solidly in the theoretical realm...

[Cancer]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

The populations of muons (created in the upper atmosphere by collisions of cosmic ray particles with air molecules) as a function of altitude is in accord with time dilation. The lifetime of a muon is less than the time needed for the particles to travel the distance from upper atmosphere to sea level, unless their "internal clocks" slow down because they are at high velocity.

 

There was an article about the GPS system in Physics Today about a decade ago ... sometime in the late 1990s ... so I can't recall the details now. You have to include relativistic terms in the processing of the GPS signals or you have errors of as large a hundred meters in the position you compute.

[Jhaierr]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Must... resist urge... to change... major... to physics.

 

This would be very exciting if it turns out to hold up under scrutiny. I never really liked the "dark matter" explanation for things. (Of course, I'm no physicist.)

[Clonus]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Have we actually observed time dilation though? I thought that was still fairly solidly in the theoretical realm...

 

They've taken an atomic clock up and flown it around at supersonic speeds to measure the difference in time, so no, not really

[Nyrath]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

Have we actually observed time dilation though? I thought that was still fairly solidly in the theoretical realm...

No, it has been observed.

http://en.wikipedia.org/wiki/Time_dialation#Experimental_confirmation

 

As a matter of fact, the GPS system you use to navigate your car has to make corrections for time dilation effects from the satellites or it will display incorrect positions.

[KawangaKid]

Re: YACttTOR (Yet Another Challenge to the Theory of Relativity): Space-Time no More

 

See, this is why there should be Science Fiction RPG play in schools. You learn so much stuff from an INTERESTING framework. Actually, the same argument could be made for super-hero games...