Wormholes

vincentm

Not sure what section this would belong in but; How far from a possibility are they?

Danger

There's a very strong possibility for their existence, as long as you're not thinking in the Science Fiction popularization aspect. It's next to impossible that you could ever find, create, or maintain a wormhole big enough for a rabbit to pass through, let alone a spacecraft. The amount of negative energy required to sustain the input end would be more than most of the positive energy in the universe. You could also never determine where the other end would be.

vincentm

I read that, although they are not possible at this time (and who knows when they will be) That the theory of them don't violate the laws of physics.

Danger

Not the laws, just the practicality. It's like saying that theoretically you can achieve 99% of light speed in a spacecraft, but where would you get the energy to do it?

scott_alexsk

How would one create create the path if all conditions were ideal.

setAI

the most realistic and practical way of exploiting wormholes would be to find natural microscale wormholes that theoretically connect with random locations and instead of trying to open them up for large matter objects- you simply transmit 'uploaded' minds/AIs/ information/ etc in the form of photons through them- if you can figure out a way to send nuclei or even electrons through- you could send a few partcles programmed to build-up into complex nano-devices that could build bodies and facilities/tools for the transmitted minds at the other end

scott_alexsk

Yes but could one create one with ideal conditions? How would this be done?

pervect

As I recall, you can't create wormholes classically unless you already have a time machine. You can search the forums for a more detailed quote, IIRC this came from Kip Thorne's excellent book "Black holes and Time Warps: Einstein's Outrageous Legacy"

The more-or-less standard idea, (due to Morris-Thorne IIRC), is that one finds a prexisting natural wormhole that is present only at a quantum scale, and stabilizes it with negative energy, rather than creates it from scratch.

Estimates I've seen put the negative mass to stabilize a wormhole much lower than the mass of the universe - a few Jupiter's should do the job :-).

I don't recall exactly where I got this figure, though, so take it with a grain of salt. (But take the other larger figure with a grain of salt as well, unless the source for it can be tracked down).

The details of where to find a few Jupiter's worth of negative mass are left to the would-be wormhole engineer.

If one only wants to be able to transmit hard gamma rays through the wormhole, and not any form of matter, the negative-mass requirement might be lower.

Dr.Brain

By definition , Worm Holes are 'black holes' and 'white holes' joined end to end. The existence of hypothetical white holes is still in question.White holes are possible mathematical , deduced from time-inverse of relativity equation concerning Black Holes.White Holes is ineluctable as of now because it is known to emit enormous amounts of energy , as black holes are difficult to spot , the white holes should be easily seen whihc hasnot been the case as of now.

BJ

George Jones

Although some wormholes do involve black holes and white holes, this not a standard definition of the term "worm hole". In particular, one of the motivations of Morris and Thorne was to find wormholes solutions that do not have any event horizons. They were "successful".

Fomulating a precise definition of "wormhole" is not easy. From Matt Visser's Lorentzian Wormholes:

"If an asymptotically flat spacetime M possesses a causal curve [itex]\gamma[/itex] that stretches from past null infinity to future null infinity, such that [tex]\gamma[/itex] is not deformable to the trivial causal curve, then M posseses a traversable wormhole and the curve [itex]\gamma[/itex] is said to go through the wormhole."

Causal curves are the worldlines of photons and massive particles. The trivial causal curve runs from the infinite past (from past null infinity) to the infinite future (to future null infinity) while staying in the asymptotically flat region of spacetime (via spacelike infinity).

Regards,
George

Danger

I also don't know where I got that estimate, but I'm pretty sure it was just a SciAm article sometime last year. The reference was to negative energy, though, not mass. If a few Jupiters worth of negative mass was converted to negative energy according to e=mc^2, it might do the trick.

ohwilleke

I'd say that the evidence for the existence of wormholes is nil, and that the theoretical basis for them is pretty weak.

As far as definitions go, one pretty reasonable one would be a phenomena that can move energy and/or matter, in at least one direction, from one point in space-time to another point in space-time, while not passing through any point at an arbitrary distance from one of the points in a local region around on of those points.

In other words, a wormhole is basically a non-local connection between points.

I think you could further classify wormholes as one way v. bidirectional, and as those that connect points within the same universe v. those which connect different universese (i.e. you can't get from there to here except via the wormhole).

The only prominent nominee I've seen for being a white hole is the big bang. In Smolin's CNS, a black hole event horizon defines the boundary between one universe and the next, and the black hole matter becomes the Big Bang of the next universe. (For the record, I've vehemently argued against Cosmic Natural Selection as a valid theory).

Another distinction that could be made is between a "topological wormhole" and a truly "non-local wormhole". A topological wormhole is the Wrinkle in Time concept. If in fact the universe has more than 4 dimensions, and as GR implies they are not completely flat (although empirically evidence seems to imply that it is very nearly flat). Basically, is the universe is mostly confined to a 4D brane one could imagine curvature in another dimension connecting two points which are not otherwise local within the brane.

On the other hand, a truly non-local wormhole would connect two points through a means other than the curvature of time-space.

I do caution against discounting the importance of very small scale and ephemeral, but predictable phenomena (consider quantum tunnelling). A fraction of a second burst of photons through a wormhole connecting two distant points, if one could be created or maintained predictably, would be revolutionary, even if they could be maintained for only a fraction of a second at a time and weren't big enough to allow the passage of even an electron.

George Jones

Different people have different ideas how much. For example, Matt Visser says not very much. Ford and Roman, say, "Hang on; things aren't so simple!"

Ford and Roman have written in Scientific American.

Regards,
George

George Jones

Yes.

Depends on whom you listen to.

I'm not sure I know what you mean. Could you elaborate?

Regards,
George