• Question: how are blackhole's formed?

    Asked by spencer1x to Adam, Catherine, Karen, Leila, Nazim on 14 Mar 2012. This question was also asked by hannah4edsheeran, hannah1998, yassie, georges.
    • Photo: Karen Masters

      Karen Masters answered on 13 Mar 2012:

      When massive stars run out of fuel they will explode in what we call a Supernova. Now actually that’s really the star collapsing in on itself. Eventually some force will stop the collapse and the outer layers bounce back in a dramatic explosion. If the star is so massive that nothing can stop the collapse then it will leave behind a black hole.

      There are also supermassive black holes in the centres of most galaxies. How they formed is a bit of a puzzle actually. They are incredibly massive – they would have to be made of millions of black holes from stars…. and we see them really early in the history of the Universe. Maybe one of you could become an astronomer and figure out how they formed in a few years time.

    • Photo: Leila Battison

      Leila Battison answered on 13 Mar 2012:

      Black holes are formed when something has so much mass that its gravity makes it collapse in on itself, and pull in everything in around, including time and light. That’s why they’re black, because light can’t escape from them.

      For them to form, the pressure inside them has to be less than the gravity pulling in on them. This often happens when stars run out of things to burn, so the huge mass can’t be held in a big sphere any more by burning inside.

    • Photo: Adam Stevens

      Adam Stevens answered on 13 Mar 2012:

      They are formed in the death of a giant star.

      A star that’s big enough will have nothing to stop all that mass collapsing into a small enough space.

      A black hole is just a place in space where there’s too much mass in one place, so that the gravity of the mass means that to escape from orbit around it, you would have to go faster than the speed of light.

    • Photo: Nazim Bharmal

      Nazim Bharmal answered on 14 Mar 2012:

      Certain stars are very large and they can only stay that big because the nuclear reactions in their centre are powerful enough to stop them collapsing on in them self. When the nuclear reactions run out of fuel, the collapse can begin. Depending on how big the star is, you can get various types of objects.

      A black hole made from a star is when the collapse is so large that nothing can stop it in time for an event horizon to be formed. Now the event horizon is where time, basically, stops because light can’t escape from it. Since light can’t get out, the event horizon looks black from far away hence a black hole. If you are close, however, you can actually go through the event horizon (but then you can’t escape) and you can see ‘inside’ the black hole.

      The physics starts to go really crazy but some people predict it can be quite bright inside. But nothing survives for very long. And then you hit the singularity at the centre of the black hole, which is where science fiction is as accurate as real science i.e. you have to start guessing.

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