Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Hawking radiation from not-a-black-hole?

  1. Dec 18, 2015 #1
    Since Schwarzschild solution describes exterior not only of black holes, but of any spherically symmetric non-rotating objects, then any such object should emit Hawking radiation, no?

    Then how exactly is that working?

    Let's set up a thought experiment. Say, we construct a spherically symmetric non-rotating object from ordinary atoms (say, a sphere of pure silicon). We know exactly how many atoms is there. We cool it to zero K (IOW: it has no thermal energy to create any particles) and position it in an empty space, devoid of any matter and radiation.

    Now we observe it. When we detect a quantum of "Hawking-radiated" emission, where did the object get energy to create it? Is there one less Si atom in the object?
  2. jcsd
  3. Dec 18, 2015 #2


    User Avatar
    2017 Award

    Staff: Mentor

    Objects with a finite radius have a different metric inside. In particular, you are missing the event horizon that is crucial for Hawking radiation.

    You don't need a black hole for a horizon, however. You can create horizons for quasiparticles in matter (example) or with accelerations (Unruh effect).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook