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*To*: starship-design@lists.uoregon.edu*Subject*: starship-design: Blackhole*From*: TLG.van.der.Linden@tip.nl (Timothy van der Linden)*Date*: Wed, 20 Aug 1997 17:50:56 +0100*Reply-To*: TLG.van.der.Linden@tip.nl (Timothy van der Linden)*Sender*: owner-starship-design

Steve, > > Are you sure about black holes producing more energy the smaller they are? > > I've heard that they evaporate faster and faster, but that's only because > > the surface:volume ratio gets bigger. I'd guess the total evaporated energy > > gets less if the surface gets less. > > But indeed if you would have 1000 small holes instead of 1 big with the same > > total mass, you'd probably be better of with the 1000 small holes. > >I believe Isaac is right about this. Very small black holes evaporate >rapidly, to the point of being violently explosive. The evaporation >rate is a function of the gravity gradient at the event horizon, which >goes asymptotic as the mass of the hole approaches zero. Imagine the >energy release from a few hundred tons of mass turning into a spray of >high-energy subatomic particles within a tiny fraction of a second. I already wrote that it is said that smaller black holes evaporate faster, and I also assumed the radiation per surface area was bigger. The total surface however is getting smaller too. My suggestion was that the total surface got smaller faster than the emission rate per surface area gets bigger. So you didn't really address the point I made. After having thought things over, I conclude that the radius decreases linearly with the mass (R=2G*M/c^2). So the surface decreases quadratically while the mass decreases linearly. The question is: Does the "gravity gradient" increase linearly, quadratically or even faster with the radius decrease? Timothy

**Follow-Ups**:**starship-design: Blackhole***From:*Steve VanDevender <stevev@efn.org>

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