All You Need To Know About Black Holes

Black holes are one of the greatest mysteries of the universe. Accepted for the most part much of what we know about them is conjecture, extrapolated from what can be observed and inferred by what we know about the nature of the universe. These great voids in space may even serve as gateways into alternate universes.

What Is A Black Hole?

A black hole is a region in space that is so dense that not even light can escape its gravitational pull. The name comes from the fact that light can’t emanate from it, and if seen against a lighter background it would appear to be a dull black disk. Black holes can be created in a few ways, theoretically, but general it is thought that when a star reaches a critical mass it collapses in upon itself, and if the mass is sufficiently high it becomes a black hole. The idea that black holes can capture light itself has been around since the 18th century, but it wasn’t until Albert Einstein and his theory of general relativity in 1916 that the model of black holes currently accepted as fact was established.

How Can We See A Black Hole?

If a black hole can trap light, and thus be considered invisible, how can it be seen? As mentioned above if a lighter object, such as a nebula, were to be viewed behind the black hole then the dull disk would appear- in theory. Otherwise black holes are observed by observing their impact on the space around them. The swirling gas and matter that is being pulled in passed the event horizon (the edge of the black hole past which nothing can escape), known as an accretion disk, would be observable, with a noticeable hole at the centre.

Super Massive Black Holes!

The “average” black hole would have a mass several times that of our Sun, and is called a stellar-mass black hole. There are black holes that are larger and some, in theory, that are smaller. Larger objects are called Super Massive black holes and can be in the region of millions—or even billions—of times the mass of our sun. Theoretically there are intermediate mass black holes between the largest and the stellar mass, and even micro black holes. There was at one point concern of a “black hole gun”, due to the fact that the Large Hadron Collider (the world’s largest particle accelerator) may be able to create miniature black holes. Upon further study, however, it was determined that the particle collision that takes place every day in nature is much more volatile than what could be produced by the LHC. As any micro black holes that may have been created in nature this way were too unstable to accrete matter, as evidenced by the lack of Earth’s destruction, it is thought the same will apply to the LHC when it comes online in 2008.

Black Hole Theory

As pointed out, much of what we “know” about black holes is actually what we surmise. Stephen Hawking, one of the greatest astronomic minds of our age, has floated theory about what happens to objects that enter a black hole that sounds more appropriate to science fiction and fantasy than science. Until such time that matter that enters a black hole can be retrieved—an act that our current understanding says is impossible—much of the mystery surrounding black holes will remain as such.