Astronomy Prof. Tolbert advises, "Don't ever stick your arm in a black hole."
A black hole is a massive star that has collapsed and become infinitely dense. If you stick your arm in there, you have to move faster than the speed of light to get it out, Astronomy Prof. Steven Balbus said. Once your arm was inside, you would have to move your arm faster than the speed of light to get it back out of the black hole.
But there is no real "in" or "out" to a black hole. So it's not really a "hole," but more like a designated area of intensely compacted space. If it was feasible to be in space standing next to a black hole, you would not even realize it was there. A black hole has no real surface.
The escape velocity of a black hole - the speed at which some object like your arm would have to travel to get out of the black hole - is equal to the speed of light, Balbus said.
As you approach the black hole, the pull of gravity at your feet would be greater than the pull of gravity at your head. The result would be that the black hole would stretch you out like a piece of string before you could ever get close enough to put your hand inside it. The atoms in your body would act like the gas molecules, spinning at the speed of light, so fast that the friction causes them to fall into the black hole.
When gases approach a black hole, they spin at light speed around the edge of something called the event horizon, which is the black hole's "point of no return." Nothing that passes the event horizon can ever escape the gravitational pull of the black hole.
Because the gas atoms are spinning so fast, the gas particles rub up against one another, creating a lot of friction and eventually causing them to fall into the black hole.
Currently, researchers at the universities of Texas, California at Santa Cruz and Michigan are finding out whether galaxies came before black holes or vice versa. They theorize that the size of the galaxy determines how large the black hole gets.
And Michael Garcia of NASA's Chandra X-ray center is looking at images of Andromeda Galaxy because he noted the temperatures of the black holes there are significantly lower than those of black holes elsewhere. This research may reveal more about the nature of black holes in general.
The Question of the Week column is a new feature of the Health and Science page. If you have a science-related question, please email cavdaily@cavalierdaily.com.
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