Richard F. Holman is a professor of physics at Carnegie Mellon University. He offers this response:
Wormholes are solutions to the Einstein field equations for gravity that act as "tunnels," connecting points in space-time in such a way that the trip between the points through the wormhole could take much less time than the trip through normal space.
The first wormhole-like solutions were found by studying the mathematical solution for black holes. There it was found that the solution lent itself to an extension whose geometric interpretation was that of two copies of the black hole geometry connected by a "throat" (known as an Einstein-Rosen bridge). The throat is a dynamical object attached to the two holes that pinches off extremely quickly into a narrow link between them.
Theorists have since found other wormhole solutions; these solutions connect various types of geometry on either mouth of the wormhole. One amazing aspect of wormholes is that because they can behave as "shortcuts" in space-time, they must allow for backwards time travel! This property goes back to the usual statement that if one could travel faster than light, that would imply that we could communicate with the past.
Needless to say, this possibility is a disturbing one; time travel would allow for a variety of paradoxical situations, such as going back into the past and killing your grandfather before your father was born (the grandfather paradox). The question now arises of whether it would be possible to actually construct a wormhole and move it around in such a way that it would become a usable time machine.
Wormhole geometries are inherently unstable. The only material that can be used to stabilize them against pinching off is material having negative energy density, at least in some reference frame. No classical matter can do this, but it is possible that quantum fluctuations in various fields might be able to.
Stephen Hawking conjectured that while wormholes might be created, they cannot be used for time travel; even with exotic matter stabilizing the wormhole against its own instabilities, he argued, inserting a particle into it will destabilize it quickly enough to prevent its use. This is known as the Chronology Protection Conjecture.
Wormholes are great theoretical fun, and are seemingly valid solutions of the Einstein equations. There is, however, no experimental evidence for them. This should not stop any budding science-fiction writers from using them as needed!
William A. Hiscock is a professor of physics at Montana State University, Bozeman, and is the director of the Montana Space Grant Consortium. He adds some details:
A wormhole is a tunnel-like connection through space-time, much like the real tunnels bored by worms in a (Newtonian) apple. At present, space-time wormholes are only theoretical constructs derived from general relativity; there is no experimental evidence for their existence. Nevertheless, theoretical physicists study the mathematical properties of space-times containing wormholes because of their unusual properties. Study of such strange geometries can help better distinguish the boundaries of behavior permitted in the theory of general relativity, and also possibly provide insights into effects related to quantum gravity.
A wormhole has two mouths connected by a "throat," and provides a path that a traveler could follow to a distant point. The path through the wormhole is topologically distinct from other routes one could follow to the same destination.
What is meant by topologically distinct? If an ant wished to crawl from one side of an apple to another, there are many possible paths on the surface connecting the starting point to the destination. These paths are not distinct topologically: a piece of elastic string fixed at the starting and ending points, and lying along one such path, could be slid and stretched over the surface to lie along any other such path. Now imagine that the ant instead crawls through a wormhole in the apple. A piece of string passing through the wormhole cannot be smoothly moved in such a way as to lie along one of the surface paths (or through another wormhole with the same end points but different route).
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7 Comments
Add CommentThe past has already been created, so if you killed your grandfather, all it would create is a hole in time and the rest of the timeline would continue as it was. Also, just because Physics doesn't know how to control a wormhole doesn't mean it can't be done---only that, at the present time, Physics it too stupid to know how. If control of a wormhole is the only drawback to riding your skateboard along the length of it, it is highlly unlikely that, at some future time, someone won't shoot the worm, much as the do rapids, nowadays.
Reply | Report Abuse | Link to thisthe paradox is that if you kill your grandfather then your father is not born then you are not born and cant go back and kill your grandfather, thus a fatal paradox. But there is alot in what you say that i do agree with.
Reply | Report Abuse | Link to thisIf we can create a wormhole SAFELY then there is no reason not to experiment with it, however as i have stated elsewere, we as a species are too arrogent to do such a thing SAFLY. we think that just becouse we can do it it will not rip space time to shreds. It would be theoretically possable to "empty" space of emergy to facilitate the negative mass energy migrating to that point, howevere there is a lot to be said about "poking sticks at wild bears".
hello, this is a very interesting topicof mine..
Reply | Report Abuse | Link to thisthus i request to all those who know any thing about wormhole, then please send me to my e-mail
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I would simply disagree with that paradox effect. In some points, what I understand is that dimension and time are two different scenarios whereas dimension is a parallel in space but not time. Wormhole if true can make us travel multi-parallel dimension connection in two different points in time. It means that once you travel through the wormhole you will be in another dimension of space and time, and if it is possible to transport physical objects or body through that wormhole, that object/body will not effect the state of time and events because of the two-dimensional world scenario. If you kill your grandfather in another space and time that will not cause an effect to the dimension where you came from. cheers! :)
Reply | Report Abuse | Link to thisI would simply disagree with that paradox effect. In some points, what I understand is that dimension and time are two different scenarios whereas dimension is a parallel in space but not time. Wormhole if true can make us travel multi-parallel dimension connection in two different points in time. It means that once you travel through the wormhole you will be in another dimension of space and time, and if it is possible to transport physical objects or body through that wormhole, that object/body will not effect the state of time and events because of the two-dimensional world scenario. If you kill your grandfather in another space and time that will not cause an effect to the dimension where you came from. cheers! :)
Reply | Report Abuse | Link to thisWormholes are made of dark matter particles that cannot be consumed by black holes and do not interact with normal matter except by being gravitational reverse black holes called white holes. No evidence refutes this, even scientists want to claim that dark matter is intemediate or millimeter sized black holes which would collide explode radiate if so densely packed into clumpy galactic halos around visible matter. Check out the latest news and theories at www.quantauniverse.com
Reply | Report Abuse | Link to thisI've always felt this paradox is more a function of our egos. After all, unless I am mistaken (which happens often in science!) particles from the past are constantly showing up in the present to "kill" other particles, some of which might be their future selves. To the universe, we are just a collection of such particles so why couldn't that collection go back and kill the collection it came from?
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