Sunday, July 15, 2012

Through The Wormhole: Beyond The Darkness..!!

What is the universe made of? If you answered stars, planets, gas and dust, you’d be dead wrong. Thirty years ago, scientists first realized that some unknown dark substance was affecting the way galaxies moved.Today, they think there must be five times as much dark matter as regular matter out there. But they have no idea what it is – only that it’s not made of atoms, or any other matter we are familiar with. And Dark Matter is not the only strange substance in the Universe – a newly discovered force, called Dark Energy, seems to be pushing the very fabric of the cosmos apart.

The composition of the universe may seem straightforward, something you mastered back in your junior high science class – galaxies made up of planets and stars, stars made up of burning gases and dust. But this idea of the universe only includes the parts that we can see, either with the naked eye or even with powerful telescopes.According to scientists, the visible portions of the universe account for less than 95 percent of what is actually out there in the great expanse of space. Much of the universe is made up of something we can’t see. We call this something “dark matter,” and we only discovered its existence because something else was missing.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.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.

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).