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>The time a black hole takes to evaporate is >proportional to the cube of its mass. The power of >Hawking radiation is <I>inversely</I> proportional to >the mass of the black hole, given by <B>P = >K/M²</B>, where <B>K</B> is a complex >constant equal to <B>3.563 x 10³² W >kg²</B>. > >The size of a black hole's event horizon is >proportional to its mass, and is given by ><B>R_s = 2GM/c². > >A black hole weighing 200 pounds on the surface of the >Earth would have about 90 kilograms of mass, and would >be about 2.67 X 10^-20 centimeters in >diameter. (This is very approximately >1,000,000,000,000 times smaller than the atoms in your >brain, incidentally.) A black hole of this size would >almost instantly disappear in an incredible burst of >energy, expressed as Hawking radiation. > >If a black hole weighing 200 pounds appeared in your >brain, you would probably not get a chance to feel a >200-pound weight dragging your head toward the ground >because your head would be vaporized by the black >hole's explosively rapid evaporation into pure energy: > >"...The Hawking radiation itself would consist of >fiercely energetic particles, antiparticles, and gamma >rays. Such radiation is invisible to the human eye, so >optically the evaporating black hole might look like a >dud. However, it is also possible that the Hawking >radiation, rather than emerging directly, might power >a hadronic fireball that would degrade the radiation >into particles and gamma rays of less extreme energy, >possibly making the evaporating black hole visible to >the eye. Whatever the case, you would not want to go >near an evaporating mini black hole, which would be a >source of lethal gamma rays and energetic particles, >even if it didn't look like much visually." > >"...In the final second of its existence, the mini >black hole radiates about 1000 tonnes of rest mass >energy. Such an explosion is large by human standards, >but modest by astronomical standards. An evaporating >black hole would be detectable from Earth only if it >went off within the solar system, or at best no >further away than the nearest star." > >)<A rel=nofollow target=_blank >HREF="http://casa.colorado.edu/~ajsh/hawk.html">referen >ce</A> for the quote above) > >Very interesting stuff, black holes and Hawking >radiation. All of the material in this post is >available from science sites on the Internet, >incidentally.

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