• Question: what causes black holes?

    Asked by lildannix to Chris, Eva, Michael, Paddy, Philip on 15 Jun 2011.
    • Photo: Chris Jordan

      Chris Jordan answered on 14 Jun 2011:

      A very large amount of mass in a very small space. There’s one (an SMB – Super Massive Blackhole) at the centre of our galaxy. Scientists have seen stars orbiting it and have calculated that it must have a mass of around 4 million times our SUN. http://en.wikipedia.org/wiki/Sagittarius_A*

    • Photo: Paddy Brock

      Paddy Brock answered on 14 Jun 2011:

      Cool, I had no idea, but now I know. Thanks Chris!

    • Photo: Michael Wharmby

      Michael Wharmby answered on 14 Jun 2011:

      Black holes form as one of the dying stages of a star. I’d have to ask Chris for a better why, but at some point the star collapses in on itself and all that mass (as Chris says) is concentrated in a very small space and forms a black hole, which sucks *everything* around it in, even light (which is why it’s black). Importantly though, it isn’t actually a hole, it’s still an object, just a super-dense object.

    • Photo: Eva Bachmair

      Eva Bachmair answered on 14 Jun 2011:

      That would be fun for my brother. He is into black holes.

    • Photo: Philip Denniff

      Philip Denniff answered on 15 Jun 2011:

      I would stick with the answers of those that know rather than me guessing. If it is gravity that holds the black hole together, is it also gravity that makes it

Comments

  • Photo: Chris

    Chris commented on :

    Stars shine by turning mass into energy (someone asked about e=mc^2 a while ago)
    They start made out hydrogen (commonest stuff around and the simplest element) and run by fusion – ie banging 2 hydrogen nuclei together to make helium plus a bit of energy …
    When they run out of hydrogen they start turning helium into other stuff and so on, but this gets harder and harder, and when you get to Iron which is very stable, you can’t go any further because the reaction turns around and you nedd to put energy in to get fusion. All that energy streaming out of the star is holding it it in shape (like the pressure of the air in a balloon) but now the star has run out of fuel and energy, and collapses under it’s own gravity. If the start is big enough it could collapse into a black hole. Smaller stars collapse and explode just leaving a tiny spinning core (many 50kms across but as heavy as our sun).