EVIDENCE OF BLACK HOLES

EVIDENCE OF BLACK HOLES

Astronomers have found convincing evidence for a super massive black hole in the center of the giant elliptical galaxy M87, as well as in several other galaxies. In 1994, the Hubble Space Telescope data produced an unprecedented measurement of the mass of an unseen object at the center of M87. For many years x-ray emission from the double star system Cygnus X-1 convinced many astronomers that the system contained a black hole. With more precise measurements available recently, the evidence for a black hole in Cygnus X-1 is very strong.

The mathematics of general relativity is so rich, complex, and fascinating that theoretical physicists have spent years investigating the geometry of black holes, these efforts have yielded some surprising results. For instance, in the 1930s Einstein and his colleague, Nathan Rosen, discovered that the full geometry of a black hole could connect our universe with a second domain of space and time that is separate from ours.

 

Multi Universe

Some physicists, who over the years have explored the properties of the black hole's core using Einstein's equations, revealed the wild possibility that it might be a gateway to another universe that tenuously attaches to ours only at a black hole's center. Roughly speaking, where time in our universe comes to an end, time in the attached universe just begins.

The interiors of black holes are deeply mysterious places, forever beyond our view, where the accepted laws of physics provide no guide. This has not, however, discouraged physicists from speculating about what goes on there. One idea is that the shrinking interior of a black hole shrinks only so far before it rebounds as another universe with slightly different laws of physics. Not in our universe, mind it, because it is a law of black holes that nothing that is inside can ever get our again, but somewhere else. Black holes give birth to baby universes, then the universes that are geared up to produce the most black holes will spawn the most offspring universes. This brings out the idea of multi universe and all other theoretical speculations relating to black holes.

 

White Holes

The equations of general relativity have an interesting mathematical property, namely, they are symmetric in time. That means we can take any solution to the equations and imagine that time flows backward rather than forward and we will get another valid solution to the equations. If we apply this rule to the solution that describes black holes, we get an object known as a white hole.

Since a black hole is a region of space from which nothing can escape, the time-reversed version of a black hole is a region of space into which nothing can fall. In fact, just as a black hole can only suck things in, a white hole can only spit things out. White holes are a perfectly valid mathematical solution to the equations of general relativity, but that doesn't mean that they actually exist in nature.

 

Worm Holes

The combination of black and white holes is called a wormhole. A conveniently located wormhole would provide a convenient and rapid way to travel very large distances, or even to travel to another Universe. Maybe the exit to the wormhole would lie in the past, so that we could travel back in time by going through. Wormholes almost certainly do not exist. As we said above in the section on white holes, just because something is a valid mathematical solution to the equations doesn't mean that it actually exists in nature.

These mathematical curiosities have inspired some scientists to speculate about using a wormhole is a short cut to get from one place in our universe to another, or to a parallel universe. But detailed calculations reveal a major obstacle: The powerful gravity of a black hole causes the wormhole to collapse almost as soon as it forms. As a result, to get from one side of a wormhole to the other, you would have to travel faster than the speed of light, which is not possible.