what is a black hole? – MRC Festival Zone 2019

Question: what is a black hole?
- Keywords:
  black hole
Asked by anon-220349 on 12 Jun 2019.
- Rachel Hardy answered on 12 Jun 2019:
  
  A black hole is a part of space that has a gravitational field so strong that nothing can escape from it. This includes all matter and radiation, such as light. Everything that comes close to a black hole is sucked into it – nothing can escape! Black holes are made from very large stars at the end of their life cycle. These can become even bigger to form ‘supermassive black holes’ if they fuse together with another black hole, or another big star. Thankfully, there are no black holes close to earth. The nearest one has been shown to be 6,000 light years away and is 15 times the size of the sun!
- Kaitlin Wade answered on 12 Jun 2019:
  
  This is not my area of expertise at all so I will defer to Rachel’s answer, which is AWESOME.
- Rebecca Moon answered on 12 Jun 2019:
  
  Unfortunately I am a medical doctor and so my knowledge on space is pretty limited – in fact the only thing I really know is that astronauts lose bone strength when they are in space because they do not participate in any weight bearing physical activity as there is no gravity. This is one of the reasons how we know weight bearing physical activity is so important for bone health.
  
  I think there is a space zone chat board going on at the same time as this one so maybe pop your question on there and one of their experts will be able to give you a good answer I’m sure. Or maybe someone else on this board will have a space interest outside of their work and be able to help you out! Or if all else fails, try good old google!
- Marianne King answered on 13 Jun 2019:
  
  Black holes are my favourite thing to read about in space! They’re formed when massive stars reach the ends of their lives and eventually collapse under the force of their own gravity, forming an area of infinity density called a singularity – I can’t even imagine what this would be like. Even light can’t escape from a black hole! Another cool thing that slightly less massive stars do when they reach the end of their lives is that they collapse to form neutron stars. They’re only 20km across, are hugely massive. If you took a sugar cube sized chunk out of a neutron star it would weigh millions of tonnes if you put it on Earth!
- Nina Rzechorzek answered on 14 Jun 2019:
  
  This blog helped me to understand black holes a bit better, but I certainly cannot validate its contents!
  http://blogs.discovermagazine.com/badastronomy/2008/10/30/ten-things-you-dont-know-about-black-holes/#.XP_o9S2Q3EY
  Hope that helps!
- Matthew Bareford answered on 14 Jun 2019:
  
  Black holes are basically areas of extremely dense gravitational field. They are a distortion of space-time itself.
  
  What this effectively means is that they will ‘absorb’ any matter and light that comes close to them and it will not be able to escape. Black holes add the ‘absorbed’ matter to itself and grow slightly bigger with everything they get. equally, they are constantly giving off something called Hawkins radiation, which means that they are slowly losing mass and energy all the time.
  
  Black holes have amazingly long ‘lives’, they are estimated to be around for approximately 10 (with 100 zero’s after it) years before they will finally disappear into nothing as they have lost all their mass and energy.

Question: what is a black hole?

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