Faster than light

amolv06

Science

13 Apr '10 23:19

sonhouse
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17 Apr '10 02:071 edit
Originally posted by amolv06
You are correct, but here I am not concerned with how the particle attained superluminal speeds. I am only interested in the theoretical implications of a particle travelling at such speeds.
First we have to prove tachyons actually exist. So far it is just a mathematical curiosity.
If they are proven to exist, the first use for these beasts may be for communications. But that will ruin some finely tuned paradoxes.
If all that happens, we communicate a thousand times faster than light, the next step would be to convert US into some kind of tachyon field. Personally I think it's all a pipe dream, but, hey, stranger things have happened.
For instance, quantum superposition is a fact but according to some cannot be used to communicate, not allowed in quantum world, which is a shame because I can see such an entanglement used to communicate inside deep mines or inside submarines which now are limited to maybe 60 hertz bandwidth of EM when deep underwater.
zeeblebot
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17 Apr '10 06:26
http://en.wikipedia.org/wiki/Faster_than_light

Faster-than-light (also superluminal or FTL) communications and travel refer to the propagation of information or matter faster than the speed of light. Under the special theory of relativity, a particle (that has mass) with subluminal velocity needs infinite energy to accelerate to the speed of light, although special relativity does not forbid the existence of particles that travel faster than light at all times (see tachyons).

On the other hand, what some physicists refer to as "apparent" or "effective" FTL[1][2][3][4] is the hypothesis that unusually distorted regions of spacetime might permit matter to reach distant locations faster than what it would take light in the "normal" route (though still moving subluminally through the distorted region).

Apparent FTL is not excluded by general relativity. Examples of apparent FTL proposals are the Alcubierre drive and the traversable wormhole, although the physical plausibility of these solutions is uncertain.

Contents

* 1 Travel
* 2 Possibility
* 3 Justifications
o 3.1 Faster light (Casimir vacuum and quantum tunnelling)
o 3.2 Give up causality
o 3.3 Give up (absolute) relativity
o 3.4 Non-physical realms
o 3.5 Space-time distortion
o 3.6 Heim theory
o 3.7 Lorentz symmetry violation
* 4 Tachyons
* 5 General relativity
* 6 FTL phenomena
o 6.1 Daily motion of the Heavens
o 6.2 Light spots and shadows
o 6.3 Closing speeds
o 6.4 Proper speeds
o 6.5 Phase velocities above c
o 6.6 Group velocities above c
o 6.7 Universal expansion
o 6.8 Astronomical observations
o 6.9 Quantum mechanics
+ 6.9.1 Hartman effect
+ 6.9.2 Casimir effect
+ 6.9.3 EPR Paradox
+ 6.9.4 Delayed choice quantum eraser
* 7 Variable speed of light
* 8 Notes
* 9 See also
* 10 References
* 11 External links
o 11.1 Scientific links
o 11.2 Proposed FTL Methods links
zeeblebot
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17 Apr '10 06:28
Originally posted by AThousandYoung
Did you know the Star Trek Warp Drive was invented by a Mexican - and that it's not necessarily fictional?

http://en.wikipedia.org/wiki/Alcubierre_drive
Star Trek predates 1994.

http://en.wikipedia.org/wiki/Alcubierre_drive

The Alcubierre drive, also known as the Alcubierre metric or Warp Drive, is a speculative mathematical model of a spacetime exhibiting features reminiscent of the fictional "warp drive" from Star Trek, which can travel "faster than light" (although not in a local sense - see below).

In 1994, the Mexican physicist Miguel Alcubierre proposed a method of stretching space in a wave which would in theory cause the fabric of space ahead of a spacecraft to contract and the space behind it to expand.[1] The ship would ride this wave inside a region known as a warp bubble of flat space. Since the ship is not moving within this bubble, but carried along as the region itself moves, conventional relativistic effects such as time dilation do not apply in the way they would in the case of a ship moving at high velocity through flat spacetime. Also, this method of travel does not actually involve moving faster than light in a local sense, since a light beam within the bubble would still always move faster than the ship; it is only "faster than light" in the sense that, thanks to the contraction of the space in front of it, the ship could reach its destination faster than a light beam restricted to travelling outside the warp bubble. Thus, the Alcubierre drive does not contradict the conventional claim that relativity forbids a slower-than-light object to accelerate to faster-than-light speeds. However, there are no known methods to create such a warp bubble in a region that does not already contain one, or to leave the bubble once inside it, so the Alcubierre drive remains a hypothetical concept at this time.
FabianFnas
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17 Apr '10 07:54
Originally posted by zeeblebot
Star Trek predates 1994.

http://en.wikipedia.org/wiki/Alcubierre_drive

The Alcubierre drive, also known as the Alcubierre metric or Warp Drive, is a speculative mathematical model of a spacetime exhibiting features reminiscent of the fictional "warp drive" from Star Trek, which can travel "faster than light" (although not in a local sense - see below ...[text shortened]... ubble once inside it, so the Alcubierre drive remains a hypothetical concept at this time.
But again:
Star Trek uses hyperspace, Alcubierre drive doesn't.
Alcubierre drive has nothing to do with Star Trek.

If not: Explain!
sonhouse
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17 Apr '10 14:171 edit
Originally posted by FabianFnas
But again:
Star Trek uses hyperspace, Alcubierre drive doesn't.
Alcubierre drive has nothing to do with Star Trek.

If not: Explain!
There have been a lot of science fiction hyperspace drives but bringing them up in a science forum is like asking which is more real, angels or fairies.
Some of the sci fi drives talk about skipping our three dimensions by popping into a 5th or 6th dimension and moving in that realm and then popping magically back into our dimension only a million light years from where you started. Speculation is fine but there is this itty bitty problem of actually doing the physics first🙂
FabianFnas
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17 Apr '10 14:50
Originally posted by sonhouse
There have been a lot of science fiction hyperspace drives but bringing them up in a science forum is like asking which is more real, angels or fairies.
Some of the sci fi drives talk about skipping our three dimensions by popping into a 5th or 6th dimension and moving in that realm and then popping magically back into our dimension only a million light ye ...[text shortened]... . Speculation is fine but there is this itty bitty problem of actually doing the physics first🙂
The crew of Star Trek does a lot of magical things of which we have no scientific theory to make it work (yet).

But they certainly don't use any Alcubierre drive.
AThousandYoung
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17 Apr '10 18:34
Originally posted by sonhouse
There have been a lot of science fiction hyperspace drives but bringing them up in a science forum is like asking which is more real, angels or fairies.
Some of the sci fi drives talk about skipping our three dimensions by popping into a 5th or 6th dimension and moving in that realm and then popping magically back into our dimension only a million light ye ...[text shortened]... . Speculation is fine but there is this itty bitty problem of actually doing the physics first🙂
Says the fellow who tried to explain the lightsaber.

Thread 123414
zeeblebot
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18 Apr '10 01:15
Originally posted by FabianFnas
But again:
Star Trek uses hyperspace, Alcubierre drive doesn't.
Alcubierre drive has nothing to do with Star Trek.

If not: Explain!
it's ATY's position, not mine.
sonhouse
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18 Apr '10 03:45
Originally posted by AThousandYoung
Says the fellow who tried to explain the lightsaber.

Thread 123414
If you are referring to my bit on that post, at least it is within the possible realm of physics not based on hyperspace skipping or space warps. It looks like something we could build in maybe a couple hundred years of steady progress in physics and material science.
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18 Apr '10 06:491 edit
Originally posted by sonhouse
If you are referring to my bit on that post, at least it is within the possible realm of physics not based on hyperspace skipping or space warps. It looks like something we could build in maybe a couple hundred years of steady progress in physics and material science.
Nothing is beyond the realm of possibility in physics, because nothing is beyond the realm of possibility in mathematics. Although I feel ATY was just trying to take a poke at you for less than noble reasons, you too are all to quick to assert your scientific veiws without a quantitative leg to stand on, which leaves you as an open target.
jaywill
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27 Apr '10 00:222 edits
I thought that nothing can travel faster than light because that would require more enegy than exists in the universe.

I thought zeebleebot touched on this a little bit when s/he wrote

" a particle (that has mass) with subluminal velocity needs infinite energy to accelerate to the speed of light, although special relativity does not forbid the existence of particles that travel faster than light at all times (see tachyons). "
adam warlock
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27 Apr '10 11:201 edit
Originally posted by jaywill
although special relativity does not forbid the existence of particles that travel faster than light at all times (see tachyons). "
avalanchethecat
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27 Apr '10 20:14
Originally posted by amolv06
From what I've heard, special relativity doesn't forbid faster than light travel...
According to this article (http://www.scientificamerican.com/article.cfm?id=misconceptions-about-the-2005-03) Special Relativity does forbid objects from having a relative velocity in excess of that of light. They sound like they know what they're talking about.
jekeckel
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27 Apr '10 20:17
I see. I would be interested in reading the article. Unfortunately I can not 🙁
avalanchethecat
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27 Apr '10 21:07
Originally posted by jekeckel
I see. I would be interested in reading the article. Unfortunately I can not 🙁
Really? Sorry, maybe I'm not posting the link right. It's from March 2005 issue of Scientific American by By Charles H. Lineweaver and Tamara M. Davis, if that's any help.

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Faster than light