one of the most interesting things about a black hole is their entropy; it is proportional to its event horizon. This leads to many startling conclusions. For example:

The maximum amount of information (stuff) that can be stored in a container of a certain volume (any container! not just black holes) is proportional to the surface area of the container, NOT THE VOLUME of the container.... Is your mind blown yet?

This post was edited by Azrad on Mar 1 2010 10:46pm

According to the general theory of relativity, a black hole is a region of space from which nothing, including light, can escape. It is the result of the deformation of spacetime caused by a very compact mass. Around a black hole there is an undetectable surface which marks the point of no return, called an event horizon. It is called "black" because it absorbs all the light that hits it, reflecting nothing, just like a perfect black body in thermodynamics. Under the theory of quantum mechanics black holes possess a temperature and emit Hawking radiation.

Despite its invisible interior, a black hole can be observed through its interaction with other matter. A black hole can be inferred by tracking the movement of a group of stars that orbit a region in space. Alternatively, when gas falls into a stellar black hole from a companion star, the gas spirals inward, heating to very high temperatures and emitting large amounts of radiation that can be detected from earthbound and Earth-orbiting telescopes.

Astronomers have identified numerous stellar black hole candidates, and have also found evidence of supermassive black holes at the center of galaxies. After observing the motion of nearby stars for 16 years, in 2008 astronomers found compelling evidence that a supermassive black hole of more than 4 million solar masses is located near the Sagittarius A* region in the center of the Milky Way galaxy.

at 99.999% of the speed of light perhaps.



The gravitational force is so great that not even light photons escape beyond the event horizon, It's invisible in the purest sense.

This post was edited by Serdra on Mar 2 2010 03:06pm

still 1k+ years

This post was edited by HeLiCaL on Mar 2 2010 04:59pm

Black holes have yet to be proven to exist conclusively.

granted. But you could make this same argument about Alpha Centauri A:

Based on observation and what we think we know about the laws of the universe, it is safe to say that Alpha Centauri A is a star that is a little more than 4 light years away.

Based on observation and what we think we know about the laws of the universe, it is safe to say that many black holes exist.

To reformulate your statement:"'Alpha Centauri A has never been proven to exist conclusively".

This post was edited by Azrad on Mar 2 2010 05:14pm

Alpha centauri is directly observable. Black holes aren't.

We are coming dangerously close to philosophy. I'm curious to what definition of "directly" you are using. I'm betting it has something to do with measuring photons. Which of course is how black holes are found as well...

How else do you explain a bend in the light emitted from stars that are observeable on a regular basis?

We can look at Alpha Centauri with a telescope. We cannot do the same with a black hole, all we can see is gravitational lensing which is indirect evidence at best.