- #1
NanakiXIII
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Homework Statement
Show that a black hole's event horizon will never shrink due to a Penrose process.
Homework Equations
[tex]M_{ir}^2 =\frac{1}{2}(M^2 + \sqrt{M^4-J^2})[/tex]
The Attempt at a Solution
It is easy to show that the irreducible mass will never decrease, and I know of a result that states that the surface area of the event horizon is proportional to the square of the irreducible mass,
[tex]A = 16 \pi M_{ir}^2.[/tex]
This proves what is asked, but I am stuck on deriving the relation between the surface area and the irreducible mass.