Beyond light

By what means might superluminal communication manifest?

  • Quantum tunneling

    Votes: 2 13.3%
  • Wormholes

    Votes: 5 33.3%
  • Inflationary acceleration

    Votes: 2 13.3%
  • Dark energy

    Votes: 1 6.7%
  • Higgs true/false vacuua

    Votes: 2 13.3%
  • Bell entanglement

    Votes: 5 33.3%
  • Mental telepathy

    Votes: 0 0.0%
  • FTL signaling is impossible

    Votes: 7 46.7%

  • Total voters
    15
3,073
3
By what means might superluminal communication manifest?
 

russ_watters

Mentor
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You forgot one option: it won't.
 

RuroumiKenshin

wormholes, negative energy!

Russ: How about negative energy? You could manipulate that and create wormholes, which thus allow superluminal travel.
check this out:

[Removed Broken Link]
 
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russ_watters

Mentor
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Russ: How about negative energy? You could manipulate that and create wormholes, which thus allow superluminal travel.
Naaa. How do you get anything coherent out of a black hole?
 

RuroumiKenshin

in a vacuum, not a black hole. In addition to the fact that a perfect vacuum is impossible, there is also the negative energy. There could be 0 positive energy, but tons more of -E.
did you take a look at the site I mentioned above? it talks about the whole plight in detail.(it has a really cool picture of a wormhole too).
 
351
0
Talking about superluminal velocities is really pushing the boundaries of physics. As far as I know, wormholes are the only option aside from lucky quantum tunneling. And worholes are walking on shaky ground. It takes negative mass, something that may not exist, to hold one of them open enough to let us through. Sounds to me like sticking something into an equation 'cause it solves the problem, but doesn't exist in reality. Maybe like tachyons? It's a possibility, don't get me wrong. But it's out there a ways. At least that's how it seems to me.
 
3,073
3
russ_watters
You forgot one option: it won't.
You overlooked the last option.
 
351
0
Way to shoot him right down Lbooda. I must admit, however, to not really looking at the poll options either...
 
46
0
I think the only theoretical candidate is probably a wormhole. However as previously mentioned the ability to "prop" wormholes open depends on an exotic state of gravitational repulsion. Dark Energy/Matter (which we no little about) and also possible vacuum states that allow for negative energy densities (i.e. Casimir Effect) are possible candidates that create wormhole stability. However of course there is the matter of generating the wormhole to begin with. So its all very skeptical grounds at this point. The only other possibility is perhaps entangled states. As far as we know now Bell Entanglement cannot be sued to transmit any “useful” information. However this may all change with increasing knowledge of entangled states. Already a photon has been teleported by a team in Australia and further research in Quantum Cryptography is underway; both of which deal with entangled states. Perhaps there is some symmetry and logic that can be encoded with in entangled states and then exploited in a Bells Theorem like manner to allow for FTL transmission of useful information.
 

russ_watters

Mentor
18,866
5,051
You overlooked the last option.
And yet another option: Low reading comprehension. Oops.

in a vacuum, not a black hole. In addition to the fact that a perfect vacuum is impossible, there is also the negative energy. There could be 0 positive energy, but tons more of -E.
did you take a look at the site I mentioned above? it talks about the whole plight in detail.(it has a really cool picture of a wormhole too).
I read some but not all. And I must admit that what I know of wormholes is a little thin, but isn't this guy mixing two theories here? Aren't wormholes just two black holes sharing the same center (singularity)? I'm pretty sure thats what A Brief History of Time says. BTW, anyone ever notice if you lend out that book you never get it back?

Or can you get a different type of wormhole with vacuum energy? Maybe I'll read a little more.

That picture is close enough to a scene in a Star Trek episode, I believe thats where they got the idea.

Perhaps there is some symmetry and logic that can be encoded with in entangled states and then exploited in a Bells Theorem like manner to allow for FTL transmission of useful information.
Don't the same theories that explain things like quantum teleporation also imply that you can't ever send anything useful that way? The double edged sword of the Heisenberg Uncertainty principle: you CAN get something for nothing, just if you get too much of it it becomes nothing.
 
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46
0
Don't the same theories that explain things like quantum teleporation also imply that you can't ever send anything useful that way? The double edged sword of the Heisenberg Uncertainty principle: you CAN get something for nothing, just if you get too much of it it becomes nothing.
Absolutely. As far as we know now right now there is no useful information that can be encrypted in entangled states. But that does not rule out the possibility in it entirety. Future knowledge of more complex entangled states MIGHT lead to some type of useful FTL transmission. The key word is might, its all very shaky ground at this point. Before Chuck Yeager broke the sound barrier in the XS-1 in 1947 people thought is was impossible. Sure our equations for relativity and current understanding of modern physics say FTL travel is practically impossible, but there is a slight chance it may work out to be true in the future. You never really know, we are at a position when we can only speculate.
 

russ_watters

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Before Chuck Yeager broke the sound barrier in the XS-1 in 1947 people thought is was impossible.
I know you know thats an invalid analogy.
 
46
0
And it is for obvious reasons. The sound barrier was obviously theoretical possible however it simply was technologically inaccessible before 1947. Currently light speed is a theoretical maximum speed and technologically impossible to surpass. Tachyons have never been observed and relativity predicts what happens when things approach the speed of light and that objects cannot surpass the speed of light. There are those who feel relativity is not the final say concerning the speed of light. I’m not saying that I feel that the speed of light can or cannot be surpassed. I’m simply saying that we shouldn’t allow our ignorance to rule out the possibility.
 
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russ_watters

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There are those who feel relativity is not the final say concerning the speed of light. I’m not saying that I feel that the speed of light can or cannot be surpassed. I’m simply saying that we shouldn’t allow our ignorance to rule out the possibility.
I'll give you that. It doesn't seem likely to me though.
 

RuroumiKenshin


I read some but not all. And I must admit that what I know of wormholes is a little thin, but isn't this guy mixing two theories here? Aren't wormholes just two black holes sharing the same center (singularity)? I'm pretty sure thats what A Brief History of Time says. BTW, anyone ever notice if you lend out that book you never get it back?


Wormholes are NOT singularities. here's a definition:

A wormhole is a geometry of four-dimensional spacetime (for an explanation of spacetime see "spacetime" and "spacetime diagrams") in which two regions of the universe are connected by a short narrow throat. A classical large scale wormhole is a solution of the Einstein's field equations, which governs the curvature of spacetime. The most interesting thing with wormholes is that they could provide relatively easy means of travelling to distant regions of space or even of travelling backwards in time.


Why is negative energy needed to "make" a womehole?

WORMHOLE FORUMULA:
"Tie" quantum foam with a cosmic string.

Is this feasible?
 

LURCH

Science Advisor
2,546
117
My incomplete understanding leads me to believe that entanglement could be employed to this purpose. I understand the phenominon to a certain extent
(the point at which all the text written at the laymen's level leave off). At this level of understanding, there is a technique by which entanglement could be used to transmit information. The understanding of what properties or principles of QM would render this technique unusable are not yet known to me.
 

russ_watters

Mentor
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Wormholes are NOT singularities. here's a definition:
That definition is incomplete. It doesn't say how they work or what their properties are. Damn, I wish my dad would give back that book....lemme look around a little.

[five minutes later] Sweeeeeet. ABHOT online: http://cs-people.bu.edu/dbera/dload/Stephen_Hawking-A_Brief_History_Of_Time/i.html [Broken]
In 1935, Einstein and Nathan Rosen wrote a paper in which they showed that general relativity allowed what they called “bridges,” but which are now known as wormholes. The Einstein-Rosen bridges didn’t last long enough for a spaceship to get through: the ship would run into a singularity as the wormhole pinched off.
So thats where I got the singularity bit. Its still not entirely clear though. Essentially (if I understand correctly), curvature of space-time comes from gravity so doesn't that mean if you want to curve space-time a lot you need a LOT of gravity? IE a black hole? I'm still not clear on how you CREATE a wormhole.

In any case, he goes further:
to warp space-time in any other way so as to permit time travel, one can show that one needs a region of space-time with negative curvature, like the surface of a saddle. Ordi-nary matter, which has a positive energy density, gives space-time a positive curvature, like the surface of a sphere. So what one needs, in order to warp space-time in a way that will allow travel into the past, is matter with negative energy density.
Ok, negative energy is a quirk of the Heisenberg Uncertainty Principle. It has been detected and DOES exist. But like everything else in HUP, doesn't it disappear in the macro scale? Apparently not:
One can therefore ask: does quantum theory allow time travel on a macroscopic scale, which people could use? At first sight, it seems it should.
And he concludes:
Thus the possibility of time travel remains open. But I’m not going to bet on it.
So with our current state of knowledge, time travel on the macro scale *IS* theoretically possible. I wouldn't bet on it either though.
 
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Ben-CS

Wormholes do not contain singularities. However, they are unstable and prone to collapse; when a wormhole collapses, two singularities are created. The act of collapsing destroys the wormhole, resulting in two black holes (one for each mouth of the former wormhole).
 
i thought wormholes contained ring singularities. How else would you travel between them?
 

RuroumiKenshin

what's a ring singularity?


I'm still not clear on how you CREATE a wormhole.


Easy:
"tie" quantum foam with a cosmic string.

This data is from a book called "Blackholes, Whiteholes, and time machines" by Jim Khalili (sp?)

I read it a LONG time ago, but my memory's pretty good...i think
 
what's a ring singularity?
Instead of being a point in space, a ring singularity is ring shaped and can allow things to pass through. I'm not completely sure that this occurs in wormholes, but it does in electrically charged black holes.
 

RuroumiKenshin

fascinating! So is the ring a concentration of matter, in the form of a ring? I don't quite understand it, in the sense that if its in a black hole, then why isn't the black hole a singularity?
 
i don't know all the details but ring shape has to do with the charge of the black hole.
 

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