• Question: What are the factors that affect the evaporation of black hole?

    Asked by Harry to Daniel, Hannah, Maggie, Ry, Scott on 13 Nov 2017.
    • Photo: Scott Melville

      Scott Melville answered on 13 Nov 2017:

      Black holes are characterized by three numbers: their mass, how fast they spin, and if they have any electrical charge. Actually, for an outside observer, we can’t determine another other features of a black hole. So the answer to every question about black holes is usually just some combination of these three numbers 😉
      In this case it’s mostly the mass. The mass of a black hole determines it’s surface gravity, or ‘Hawking temperature’. Yes, that’s right – you can think of the black hole as having a temperature (exactly how this works we don’t really know – but it’s called ‘Black Hole Thermodynamics’, and is a very exciting area of research!). So how fast it evaporates is basically to do with how hot it is, and it’s temperature is determined by it’s mass 🙂

    • Photo: Hannah Middleton

      Hannah Middleton answered on 13 Nov 2017:

      The main factor is the “temperature” of the black hole. When things are hot, they give out radiation, like you can see with thermal goggles. So a black hole will give out radiation too depending on it’s temperature. The temperature of a black hole depends on the mass – the more massive the black hole the lower its temperature. So less massive black holes have higher temperatures and evaporate faster.

    • Photo: Maggie Lieu

      Maggie Lieu answered on 13 Nov 2017:

      The temperature affects the evaporation speed of the black hole. The more it eats, the hotter it gets and the faster it evaporates!

    • Photo: Daniel Williams

      Daniel Williams answered on 13 Nov 2017:

      So I think Hannah and Scott have given you the complete answer here – just the mass. Scott makes a great point that black holes only have three properties we can measure – mass, spin, and their charge. One interesting thing here is that we don’t know any natural process which can make a charged black hole, so it’s possible that there are only black holes with mass and spin.

      Having so few physical properties leads scientists to say that black holes have “no hair” – that is that they don’t really have obvious defining characteristics.

    • Photo: Ry Cutter

      Ry Cutter answered on 14 Nov 2017:

      Great question, the others have it covered really well so I’ll talk about Hawking radiation instead! Hawking radiation is the reason for black hole evaporation. In the weird world of quantum mechanics pairs of particles can ‘pop’ into existence. This doesn’t violate any physics because it is a particle and it’s anti-particle.
      If this ‘pop’ happens near an event horizon of the black hole (the part where light can no longer escape) the anti-particle can be sucked up while the ordinary particle escapes. This means the black hole will lose mass! We call the stream of escaping particles Hawking radiation 🙂
      Ryan

Comments