by Muhammad Fahd Waseem

Created on: June 11, 2009

Black holes, wormholes and time travel. If a person was to look up the three most intriguing words in all of physics, these would be it. What is most interesting, and satisfying, is that there is an inherent connection behind all these three phenomena. And much of it is not plain rambling, but has a lot of theoretical support.

Ground Concepts

To understand all these concepts, one needs to understand a few basics of the General Relativity theory. One of the premises of this theory is that space and time are one entity, closely meshed together. Space-time, as it is called, can be visualized like a large, outstretched rubber sheet. Gravity, which is exerted by all bodies, is then visualized as the bending effect of some object lying on that sheet. This visualization is endorsed by most of the scientific community.

Black holes

Black holes are the final stage of a dying star. Stars, which sustain themselves and their light with a continuous process of nuclear fusion, finally exhaust their fuel reserves of hydrogen (or some other light element). Normally, the energy of the fusion is enough to prevent gravity from pulling all the material together. As the fuel ends, though, gravity wins, and the star undergoes an implosion. For most stars, this is the end of life. But the larger stars, which had a lot of fusionable material to begin with, undergo a supernova explosion, and begin the process of fusion again, albeit with heavier elements. The largest stars can undergo this cycle multiple times, ending each time with a final product that is denser every time. And of even these, only the behemoths ever have a chance of attaining black hole status.

A black hole occurs when this cycle of rebirth reaches the end point in a body so dense, that gravity pulls it into itself. A gravity of a black hole is so strong, not even photons of light can escape it. Think of it like this: our rubber sheet is so bent by the black hole that even a little marble rolling further away will spiral into the dent. This then, is a black hole.

At the heart of a black hole is a point of space-time called a singularity. This is a point of infinite density, and thus, infinite mass. This is not truly infinite, of course, but large enough to be classified so. It is at this point that a wormhole may occur.

Wormholes

Wormholes are tunnels to other points in space time. As a quirk to the formation of a singularity, our rubber sheet may be bent such that it touches some other part of the rubber sheet.

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