• Question: can a black hole ever lose any of its mass? and how?

    Asked by thedestroyer to Anna, Craig, Richard, Shane, Sue on 16 Jun 2011.
    • Photo: Sue Carney

      Sue Carney answered on 16 Jun 2011:

      Hi thedestroyer.

      I’ve absolutely no idea about this. I know that black holes have so much gravity that they swallow up light, hence are black holes, but that’s the extent of my knowledge.

      One of the brain zone scientists asked for comments on one of their questions today, via Twitter, so I’ll do the same. I bet there are some physicists on here somewhere who could answer this for you. 🙂

    • Photo: Anna Williams

      Anna Williams answered on 16 Jun 2011:

      Hi thedestroyer,
      I have no idea either! We need help from the Quantum zone!

    • Photo: Shane Pennington-Cooper

      Shane Pennington-Cooper answered on 16 Jun 2011:

      Hello the destroyer, my quantum physics knowledge shines through,

      The answer to your question is yes a black hole can lose its mass, what is the reason well it is quite simple, black holes have the ability to create particles due to the black holes vacuum it can potentially cause the particle to break away as a form of energy, if energy is lost then mass is lost. I believe it was founded by Stephen Hawkings who suggested that because particles can be lost then a black hole very slowly can evaporate and disappear.

    • Photo: Richard Case

      Richard Case answered on 16 Jun 2011:

      Hello again thedestroyer,

      My brother is the sci-fi nerd, so can’t help you with this one…. Shanes answer sounds plausible enough and I will bow down to his knowledge in this area 🙂

Comments

  • Photo: Suze

    Suze commented on :

    Isn’t there the possibility of a white hole that spews out all the stuff that has been taken in by the black hole? It’s like the end of a black hole, but the white hole appears in another area of space time, connected to the black hole by a wormhole. Based on this… could you get sucked into a black hole and travel in time by being thrown out of a while hole?

    OK, I’m adding questions, not answering them… sorry!

  • Photo: Suze

    Suze commented on :

    Hang on thedestroyer, I think help is on the way in the shape of an astrophysicist studying neutron stars!

    • Photo: Evan

      Evan commented on :

      Hi there, nice to see you guys are talking about black holes here in this zone too!

      To answer your question, yes a black hole can lose mass. This mass is lost as “Hawking Radiation” (you can probably guess who that is named after). But it does it at a VERY slow rate. Actually it takes 10^67 years (that’s 1 with 67 zeroes after it) for a black hole with the mass of the Sun to evaporate. That’s way longer than the age of the Universe! And of course black holes are more likely to GAIN mass from interactions with other stars and general debris floating around in their vicinity.

      Now this 10^67 years number is different for different masses of black hole. And a very very small black hole could evaporate in a much shorter time. These “mini black holes” could evaporate in a much more reasonable time of say a few seconds or a minute. But do they exist? Hmmm, that is a tricky one. According to the rules of physics they are allowed to exist but it is tough to think of a way to make them. But this is what the chatter is about at the Large Hadron Collider – creation of mini black holes. Watch this space as if they actually do that with the Large Hadron Collider it will definitely be on the news!

      By the way don’t worry if they do – there would be no danger. Black holes don’t suck you in or anything like in movies or cartoons. From a gravity point of view the effects from a 1 kilogram black holes are exactly the same as the effects from a 1 kilogram bag of sugar (or whatever!)

      On a personal note, I found a really bright burst of radio emission which could possibly (but I don’t know if it is!!) be from the final stages of annihilation of an evaporating black hole. You can read about that in Astronomy Now magazine, June edition or listen to the latest Naked Scientists Astronomy podcast where I talk about it a bit, if you’re interested.

      Evan 🙂