'Einstein-Rosen Bridge' - Space Travel Anyone ?

I was inspired by the movie 'Contact' which I saw a few days back. I must admit that I was really intrigued by the concept of Wormholes being used in the movie for Space Travel. I started to dig up some information on whether such a concept actually existed or was it just pure hypothesis.

Here is brief summary of what I came up with...

A black hole is a region of space-time from which nothing can escape, even light. It can be said that black holes are really just the evolutionary end point of massive stars.

Black holes are the evolutionary endpoints of stars at least 10 to 15 times as massive as the Sun. If a star that massive or larger undergoes a supernova explosion, it can leave behind a fairly massive burned out stellar remnant. With no outward forces to oppose gravitational forces, the remnant will collapse in on itself. The star eventually collapses to the point of zero volume and infinite density, creating what is known as a singularity. As the density increases, the path of light rays emitted from the star are bent and eventually wrapped irrevocably around the star. Any emitted photons are trapped into an orbit by the intense gravitational field; they will never leave it.Because no light escapes after the star reaches this infinite density, it is called a blackhole.

A white hole on the otherhand is a blackhole running backwards in time. Just as black holes swallow things irretrievably, white holes spit them out. However white holes cannot exist, since they violate the second law of thermodynamics.General Relativity is time symmetric. It does not know about the second law of thermodynamics, and it does not know about which way cause and effect go.However we do. The negative square root solution outside the horizon represents another Universe. The wormhole joining the two separate Universes is known as the Einstein-Rosen Bridge.

The prediction of the existence of black holes did not trouble Einstein, but he found that the black holes contained a singularity at its centre; this is a point of infinite density where time comes to an end. At the point of the singularity, all the known laws of physics start to breakdown. For Einstein this was a very troubling thought and he did not like them, the idea that they were shielding from the outside world by the event horizon of the black hole was not enough for him and he did not like the concept that if you can not see it then do not worry about it.So he went to work with Nathan Rosen and in 1935 they produced a paper that produced evidence for a bridge between a black hole and a white hole, this was called the Einstein-Rosen Bridge.

The purpose of the paper of Einstein and Rosen was not to promote faster-than-light or inter-universe travel, but to attempt to explain fundamental particles like electrons as space-tunnels threaded by electric lines of force. However science fiction took the idea of Einstein-Rosen Bridges and applied it to moving spaceships faster than the speed of light through what was now being called ‘wormholes’.

So what Einstein originally theorised was now being used by science fiction writers to get around the problems with not being able to go faster than the speed of light that Einstein’s General Relativity had inflicted upon them.
However in the Einstein-Rosen theory the idea of objects larger than electrons being able to pass through a wormhole was not even considered and so the scenario that science fiction writers portray about the Einstein-Rosen Bridge is not correct.

The Einstein-Rosen work was disturbing to many physicists of the time because such a ‘tunnel’ through space-time, could in principle allow the transmission of information faster than the speed of light in violation of one of the key postulates of special relativity known as ‘Einsteinian causality’.

In 1865 when there was no relativity, quantum mechanics and modern cosmology Charles Dodgson wrote Alice in Wonderland a children’s story on the subject of parallel universes. There is a famous part of the story when Alice chases the white rabbit down a hole, this hole could now be described as an Einstein-Rosen Bridge. In Wonderland the laws of physics in this universe no longer applied and so strange processes could take place. It is however important to remember that Dodgson would not have known what type of mechanism would allow this to happen. In fact this idea,of using a ‘wormhole’ to travel large distances was used by Sagan in writing a novel ‘Contact’ in 1985. In his novel he wanted a method of moving a character faster than the speed of light though not in a manner violating Relativity.

Unfortunately, worm holes are currently more science fiction than they are science fact. A wormhole is a theoretical opening in space-time that is the mathematical solution to general relativity. If one day this was proven it could be used to travel tofar away locations very quickly. It has never been proven that worm holes exist and there is no experimental evidence for them (due to black holes being hard to detect),but it is certainly testing to think about the possibilities their existence might create.

For a more mathematical explanation please refer Einstein-Rosen Bridge