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From: weemba@brahms.BERKELEY.EDU (Matthew P. Wiener)
Newsgroups: net.space
Subject: Re: antimatter -> black hole
Message-ID: <12505@ucbvax.BERKELEY.EDU>
Date: Thu, 20-Mar-86 09:56:18 EST
Article-I.D.: ucbvax.12505
Posted: Thu Mar 20 09:56:18 1986
Date-Received: Sun, 30-Mar-86 07:20:59 EST
References: <8603181749.AA05299@s1-b.arpa> <12499@ucbvax.BERKELEY.EDU>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: weemba@brahms.UUCP (Matthew P. Wiener)
Organization: University of California, Berkeley
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In article <12499@ucbvax.BERKELEY.EDU> desj@brahms.UUCP (David desJardins) writes:
>In article <8603181749.AA05299@s1-b.arpa> REM%IMSSS@SU-AI.ARPA
>(Robert Elton Maas) writes:
>>... dropping matter into a black hole is both efficient and
>>relatively safe/simple once you have a black hole handy.
>>
>>Fortunately the only part of the matter that ends up really in the
>>hole is the part not converted to energy, so the more efficient you
>>can engineer the system the slower the hole gets massive, so with
>>close to 100% efficiency the hole lasts close to forever.
>
>   I give up.  I don't have a clue what you are talking about.  How
>is dropping things into black holes supposed to create energy (at
>"close to 100% efficiency")??

From the gravitational potential energy difference.  If I remember
correctly, there are thought experiments to prove E=mc^2 based on
dropping things slowly towards black holes.

More reasonable is extraction from the rotational energy of a spinning
black hole.  An object can be sent near the black hole's equator and
come back with higher kinetic energy than when it went out.  There's a
lot of energy available this way, as you pointed out in discussing the
earth's rotational energy.  The major inefficiency is extraction of usable
energy from the returning projectile.  There's a lovely description of
this system in MTW, using garbage in, energy out!

The only practical difficulty is finding a spare black hole lying around.

ucbvax!brahms!weemba	Matthew P Wiener/UCB Math Dept/Berkeley CA 94720