Question: how big would the earth be if it went into a black hole?

Adam Paige answered on 19 Nov 2012:

it would have zero volume inside a black hole. A black hole crushes everything down into a single point of no volume called a singularity. According to Einstein, gravity bends space, and a black hole has so much gravity it bends the space around it so completely that it doesn’t exist anymore. Anything being sucked into it disappears from the Universe.

But did you know that black holes are not black! Black holes are called black because they swallow everything including light so nothing comes out of them. Stephen Hawking realised something brilliant though. We now know that empty space is not empty. A vacuum can suddenly produce a particle and its mirror image (an antimatter particle), but these quickly come together and disappear into nothing again (a very weird idea). But, near a black hole it is possible that this particle/anti-particle pair pop into existence and then the antiparticle falls into the black hole, leaving the particle in the universe. The particle cannot disappear any more because there is no antiparticle to cancel out with, therefore the particle stays in existence and flies away from the black hole (so particles can be seen coming away from a black hole, and thus it is not black).

Also, the antiparticle that fell into the black hole makes it shrink a little. As a result black holes can actually “evaporate” and disappear by swallowing these antiparticles.