----- Original Message ----- From: "Richard Baker" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, July 25, 2002 7:35 AM Subject: Re: A puzzle
> Erik said: > > > Yeah, yeah, my mistake! Actually, I haven't done the math for a while, > > but doesn't it depend on the density of the objects as well as the > > total mass? If the objects aren't dense enough to begin with, isn't a > > singularity impossible? > > If the density is high enough that an object is within its own > Scwarzschild radius then it will necessarily collapse to form a > singularity. Things are more interesting if you keep adding more mass > to a larger body. The gravitation will compress the centre more and > more, and eventually the centre will be compressed so much that it will > be within its Schwarschild radius and so will form a black hole. > Calculations are a little tricky because you need to take into account > thermal pressure, radiation pressure and electron and nucleon > degeneracy pressures as well as radiation transport out of the body > (which is, if I recall correctly, the limiting factor in the formation > of stars from gas clouds). > So before you actually get a tobacco black hole, the cigarettes start to smoke themselves due to thermal pressure? xponent Need A Light? Maru rob
