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Hawking Radiation

  1. Dec 25, 2016 #1
    Hello, I am rather new to Physics and for a class project on exponential growth and decay in nature and I chose the effects Hawking Radiation on black holes. If anyone could help explain how the mass and temperature change over time and how to calculate them(this one especially) that would be wonderful
  2. jcsd
  3. Dec 25, 2016 #2
    Simplified, why are these decreases(in mass) and increases(in heat) expoenential.
  4. Dec 25, 2016 #3
  5. Dec 27, 2016 #4
    According to the Bekenstein–Hawking formula in black hole thermodynamics, $$S=\frac{kAc^3}{4G\hbar}$$ Consider a Schwarzschild black hole, we know that $$r_{\rm g}=\frac{2GM}{c^2},\ A=4\pi r_{\rm g}^2$$ Therefore, we can get $$M^2=\frac{\hbar c^3}{4\pi k_{\rm B} G}S$$ From thermodynamics, we learn that ##{\rm d}M=T{\rm d}S##, so we have $$T=\frac{{\rm d} M}{{\rm d} S}=\frac{\hbar c^3}{8\pi k_{\rm B}G}\frac{1}{M}$$I believe this is what you want.

    By the way, according to the Stefan-Boltzmann law, $$\frac{{\rm d}M}{{\rm d}t}=-\sigma AT^4$$ and thus you can know how the mass and temperature change over time.
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