Black Hole...is it really a hole in outer space?
27 Jan 07
Black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull. The idea of a mass concentration so dense that even light would be trapped goes all the way back to Laplace in the 18th century. You can't go faster than light, and so it means that you can't escape from a black hole
27 Jan 07
Black holes are places where gravity has become so extreme that it overwhelms everything else in the universe. Nothing can escape fro the black hole not even light. Extremely massive star 25 times heavier than our own sun become black holes as they are too heavy to stand their own gravitational force hence coillapse and die.
17 Feb 07
actually a star with a starting mass of 3.2 solar masses (ie 3.2 times the mass of the sun) can become a black hole. this is the Oppenhimer-Volkoff limit.in order to understand what happens when a body goes into a black hole just imagine a case when a person is falling inside a black hole and u are observing him. firstly, his body will get elongated (called the sphegettification effect) because the value of gravitational force increases as we go nearer to a massive body (its kind of difficult to explain this without a picture but i hope you get the idea). then the light comming from the person will appear to be red because its energy will reduce. his clock will appear to be slower as compared to urs (if they were synchronized in the beginning) as the time interval will increase. finally as his body crosses the event horizon (boundary of black hole) the intense gravity will compress it to a point but it is not possible to see this as his body would have crossed the boundary of the black hole from which light cannot come out. the last image u will have of him as suspended above the boundary because the light will take an infinite amount of time to reach you. its a pretty complex topic and lots of it is still hypothetical(due to lack of experimental evidence) but i hope i have answered ur question
• United Arab Emirates
27 Jan 07
i learnt in g.k a defnition of that. it was that, black hole has very high density and i=once a person enters into it the time doesnot run, it remains same. its very intresting thing. any astronomer/scientist here ? reply pls.