In reply to  Eric Walker's message of Fri, 2 Feb 2018 14:26:02 -0700:
>To return to gist of the thought experiment:  it seems to me that there's 
>something funny about a black hole consuming an electron and a positron, 
>gaining in the process an additional 1.022 MeV of mass-energy and thereby 
>exerting additional gravitational pull on its surroundings, and then losing 
>1.022 MeV at a later point in (our) time should the two collide (according to 
>one school of thought about black holes), exerting afterwards less 
>gravitational pull on its surroundings, when nothing has escaped the black box 
>of the system.
>I will concede that this thought experiment will not be very interesting for 
>someone who believes that matter does not make it beyond the event horizon. :)

Even if you assume that I'm wrong, I fail to see an energy accounting problem.

1) An electron positron pair is created temporarily from nothing just outside
the event horizon.
2) The electron passes through the event horizon while the positron "escapes" -
don't ask me how that's supposed to happen.
3) To pay back the debt to the Heisenberg Bank, the mass of the black hole is
reduced, by 2 electron masses, but increases by 1 electron mass due to the
swallowed electron. Net, down 1 electron mass, which ends up as the mass of the
positron. Thus the mass of the black hole is reduced by the positron mass.
4) The positron annihilates an electron elsewhere converting its mass plus the
mass of the annihilated electron into two gammas of 511 keV each.
5) Net mass loss - 1 electron (real electron somewhere in space) + 1 positron
(mass lost by black hole).
6) Net energy gain 2 511 keV gammas.

(Note that I'm trying to describe Hawking's evaporation process here.)


Robin van Spaandonk

local asymmetry = temporary success

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