freeman@spar.UUCP (Jay Freeman) (05/21/85)
In article <293@tilt.FUN> chenr@tilt.UUCP (Ray Chen) writes: > >... Here's a good way to build a >planet-buster bomb ... make up a photon torpedo style weapon (e.g. >self-propelled with a guidance system) only make the warhead a few >pound of anti-matter ... > >I'd think that be enough to seriously harm a non-gas-giant planet. > Harm -- undoubtedly; bust -- forget it. The amount of energy it takes to disperse the constituent matter of a planet, against its own gravitational pull, out to infinity; is GMM/R times a numerical constant which is not far from one (it depends on the planet's structure), where G is the gravitational constant, M is the planet's mass, and R is its radius. When a mass m of antimatter annihilates with an equal mass of conventional matter, the energy liberated is 2mcc (writing cc for c-square, of course). On plugging in numbers and solving, one finds that a planetesimal-sized hunk of antimatter is required -- a chunk several miles in diameter in the case of the Earth. And if you merely lobbed it against the surface, most of the energy would be dissipated into space, so that even more would be required. Somebody should check my calculation, of course. I seem to recall that annihilation of a gram of antimatter produces a 'bang' about equivalent to a 20 kiloton nuclear weapon. If so, a few pounds of it would have similar effect to one something like the Soviet 100-megaton bomb, which is scarcely a planet-smasher. I think it is true that if you could wave a magic wand and convert the entire planet Earth into solid TNT, and then explode it -- it wouldn't 'really' explode! That is, the TNT would go off with a large bang, but gravity would keep the resulting ball of dust and smoke from expanding to infinity. -- -- Jay Reynolds Freeman (Schlumberger Palo Alto Research)