Sri Adibhatla Soma Sekhar asked:
If light has no mass, how can a black hole capture it?
Dave - Light has no mass but it is affected by the shape of space. What Einstein worked out in general relativity was if you have a very large mass it distorts the shape of space. If you shine light across a curved piece of space it will get bent by it. A black hole is basically so heavy that it bends space so much that light will get bent a bit like a lens and come straight back into the black hole again.
Chris - Thatís why they look black, because thereís no light coming back out.
sri adibhatla soma sekhar asked the Naked Scientists:
You have to be careful when saying that light has no mass. It is true that a photon has no rest mass, but photons are never at rest.
Although not well written I'm told in the thread " Is a Black Hole a point? " I attempt to help some of you understand a black hole. There is no actual proof that light, is in fact captured by black holes ! Gabe2k2, Fri, 12th Sep 2008
But the significant concept here is not the gravitational force but the gravitational field. If an object's mass where important, then why Galilei found that all masses have the same acceleration when they fall from Pisa's tower?
Alberto - it is certainy true that what evidence we have points strongly to there being a black hole at the centre of the galaxy; but there is no definitive proof per se. DoctorBeaver, Sun, 14th Sep 2008
Ok Sir! lightarrow, Sun, 14th Sep 2008