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Faster than light

by bigbadbez
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bigbadbez
#1
Feb8-14, 03:52 PM
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People seem to be getting confused with the concepts involved in some of the faster than light travel methods that have been theoretically proposed. No, it is not possible to travel faster than the speed of light through the normal, physical universe in our current understanding of physics. E=mc2 is very powerful and unbreakable.

However, there are a number of theories being suggested that could lead to fastr than light travel - "warp bubbles" are currently the most advanced of these, which have in fact been generated at very small sizes; yes it is unlikely that we will ever move beyond these given our current understanding of science, but I imagine that if you asked Da Vinci how his plans for a flying machine were going, he might well have answered "well I have no earthly idea how we might make this work, but I know it should be possible. We just don't have the power available to make this work for real". Yeah, it took three hundred years but once the idea was there, all that was needed was science to catch up with imagination.

I may be an unrealistic optimist, but I believe that the human race is capable of pretty much anything if we put our collective imaginations into something. It will take a long time, and require innumerable advances in technology that would be both unconnected and unimaginable to us today, but even so...
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ZapperZ
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Feb8-14, 03:57 PM
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Is there an actual physics content to this, or will it be just a matter of opinion? If it is the latter, this thread belongs in the General Discussion forum, not in the physics forums.

Zz.
bigbadbez
#3
Feb8-14, 04:20 PM
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But, I'm talking about having the effect of travelling faster than light, not travelling faster than light through "normal" spacetime.

So, what I am saying is that there may be a way to alter the structure of spacetime, "folding" it to compress before, and expand after, a fixed area of spacetime. This is the theory currently being investigated, based on an original supposition by Miguel Alcubierre.

Indeed, I also found a paper by Sonny White detailing the outlying concepts of his "warp field interferometer" experiments at NASA.

http://ntrs.nasa.gov/archive/nasa/ca...2011016932.pdf

Nugatory
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Feb8-14, 04:32 PM
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Faster than light

Quote Quote by bigbadbez View Post
However, there are a number of theories being suggested that could lead to faster than light travel - "warp bubbles" are currently the most advanced of these, which have in fact been generated at very small sizes
Do you have a citation for the claim that warp bubbles of any size has in fact been generated?

The Alcubierre solution to the field equations of GR (a while back I posted a pointer to his paper here) does describe a kind of "warp bubble" that would allow faster than light travel without violating these equations. However, consistency with the field equations is a necessary but not a sufficient condition for being physically possible.
ZapperZ
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Feb8-14, 04:34 PM
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Quote Quote by bigbadbez View Post
But, I'm talking about having the effect of travelling faster than light, not travelling faster than light through "normal" spacetime.

So, what I am saying is that there may be a way to alter the structure of spacetime, "folding" it to compress before, and expand after, a fixed area of spacetime. This is the theory currently being investigated, based on an original supposition by Miguel Alcubierre.

Indeed, I also found a paper by Sonny White detailing the outlying concepts of his "warp field interferometer" experiments at NASA.

http://ntrs.nasa.gov/archive/nasa/ca...2011016932.pdf
Go back and re-read the original post that you made:'

Quote Quote by bigbadbez View Post
People seem to be getting confused with the concepts involved in some of the faster than light travel methods that have been theoretically proposed. No, it is not possible to travel faster than the speed of light through the normal, physical universe in our current understanding of physics. E=mc2 is very powerful and unbreakable.

However, there are a number of theories being suggested that could lead to fastr than light travel - "warp bubbles" are currently the most advanced of these, which have in fact been generated at very small sizes; yes it is unlikely that we will ever move beyond these given our current understanding of science, but I imagine that if you asked Da Vinci how his plans for a flying machine were going, he might well have answered "well I have no earthly idea how we might make this work, but I know it should be possible. We just don't have the power available to make this work for real". Yeah, it took three hundred years but once the idea was there, all that was needed was science to catch up with imagination.

I may be an unrealistic optimist, but I believe that the human race is capable of pretty much anything if we put our collective imaginations into something. It will take a long time, and require innumerable advances in technology that would be both unconnected and unimaginable to us today, but even so...
My point here is that this first post had very little physics content. It was based mostly on personal preference and opinion.

Secondly, even the very little physics part is incorect. E=mc^2 is NOT the reason why we have c as the speed limit. E=mc^2 is not even the FULL relativistic energy equation! You are missing the motion part of the energy! (read the Relativity FAQ subforum!). There is no obvious reason why we have c as the speed limit. This is a postulate of SR that we can only verify. We cannot derive it nor offer an explanation why it is what it is right now.

Finally, please review the PF Rules that you had agreed to. The sources we require to be used in this forum must either come from standard textbooks material, or peer-reviewed papers. If this document that you referred to has been published under the criteria that we require, please provide full citation to it. Otherwise, it cannot be used as a reference to justify/support your point.

If you wish to discuss the physics of such space-warping physics, AND are equipped to do so, then please create your discussion in the Special/General Relativity forum.

Zz.
bigbadbez
#6
Feb8-14, 04:36 PM
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You assume that I'm not aware that the physical velocity of the Alcubierre drive would not be above c - this is wrong. I'm talking about the relative speed of travel, not the absolute speed of the vessel.

At no time would the velocity actually increase above c using this principle. No wormholes are needed either. This is about compressing and expanding space-time in a controlled fashion, which is perfectly possible (theoretically) given current understanding of the Standard Model. The scientists studying the effect have reduced the projected required negative mass (antimatter) from a lump the size of Jupiter to 500kg. Thats after a couple of years' research, and they think they have worked out how to get lower than that. Another leap of that magnitude, and they'll be powering it with an elastic band and some gaffa tape...


All I'm trying to do is say there is a possibility that this can be done - travel to another star system and back within a human lifespan. I did not say it would be done tomorrow, just that there will be a way to do it. I have demonstrated that there is ongoing research into the prospect, being carried out by a world-leading scientific institutuion following up on previous study and built upon fundamental principles. I say taht this leaves the idea plausible, if not in my lifetime. You say that I am incorrect - fine, prove it.
HallsofIvy
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Feb8-14, 05:10 PM
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Quote Quote by bigbadbez View Post
You assume that I'm not aware that the physical velocity of the Alcubierre drive would not be above c - this is wrong. I'm talking about the relative speed of travel, not the absolute speed of the vessel.
Oh, dear. The fact that you think there is such a thing as "absolute speed" does not speak well for you knowledge of relativity. Talking about relative speed is good, but relative to what?

At no time would the velocity actually increase above c using this principle. No wormholes are needed either. This is about compressing and expanding space-time in a controlled fashion, which is perfectly possible (theoretically) given current understanding of the Standard Model. The scientists studying the effect have reduced the projected required negative mass (antimatter) from a lump the size of Jupiter to 500kg. Thats after a couple of years' research, and they think they have worked out how to get lower than that. Another leap of that magnitude, and they'll be powering it with an elastic band and some gaffa tape...
You were asked before to give a citation for things like this. Please do so.


All I'm trying to do is say there is a possibility that this can be done - travel to another star system and back within a human lifespan. I did not say it would be done tomorrow, just that there will be a way to do it. I have demonstrated that there is ongoing research into the prospect, being carried out by a world-leading scientific institutuion following up on previous study and built upon fundamental principles. I say taht this leaves the idea plausible, if not in my lifetime. You say that I am incorrect - fine, prove it.
Saying that something is "possible" or "plausible" is what makes this speculation and so appropriate to the General Discussion forum. And you were the one who made the assertion- it is your responsibility to prove it. No one has said you are incorrect just that you need to give some support for such an assertion.
GTOM
#8
Feb10-14, 02:36 AM
P: 110
"There is no obvious reason why we have c as the speed limit."

Maybe it is only my personal speculation, but isnt a good reason, that particle accelerators, rocket thrusters etc all operate with electromagnetic based interactions, is it nonsense?
(Rulers also expanded by EM forces, clocks count a number of EM interactions arent they? )

" The fact that you think there is such a thing as "absolute speed" does not speak well for you knowledge of relativity. Talking about relative speed is good, but relative to what?"

To me, speed compared to the frame of stars is something i would call absolute.
But correct me, where i'm wrong.

http://arc.aiaa.org/doi/abs/10.2514/6.1995-2599

I could found this abstract (i have no experience in finding correct reviewed citations). And an other washington.edu link written by John G. Cramer.

And that one http://articles.adsabs.harvard.edu/f...JRAS..36..205C

I hope they dont count crackpot.
phinds
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Feb10-14, 03:16 AM
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Quote Quote by GTOM View Post
To me, speed compared to the frame of stars is something i would call absolute.
But correct me, where i'm wrong.
You are wrong. Period. There is NO such thing as absolute motion.
Nugatory
#10
Feb10-14, 03:40 AM
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Quote Quote by GTOM View Post
To me, speed compared to the frame of stars is something i would call absolute.
There's no such thing as the "frame of stars". The problem is that when we speak of "the frame of something" that's just a convenient shorthand for "a frame in which that something is not moving". And because the stars are all moving relative to one another, there's no such frame.
GTOM
#11
Feb10-14, 05:06 AM
P: 110
http://csep10.phys.utk.edu/astr162/l...ology/cbr.html

"The indication of the above image is that the local group of galaxies, to which the Earth belongs, is moving at about 600 km/s with respect to the background radiation. It is not know why the Earth is moving with such a high velocity relative to the background radiation. "


"And because the stars are all moving relative to one another"

" when we speak of "the frame of something" that's just a convenient shorthand for "a frame in which that something is not moving""
Ok, then absolute motion is also just some convenient shorthand, compared to most convenient frame, for example the gradually shifting frame of the Solar system.
DaleSpam
#12
Feb10-14, 06:58 AM
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