this post was submitted on 04 Jan 2025
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Huh, I've always thought that a black hole required a lot of mass, not just a lot of density. Apparently not true?
They can be any mass, it's density that matters. The smaller ones will not do much damage before they evaporate.
Well, a black hole with the mass of an A4 page is gonna evaporate almost instantly, turning all of that mass into energy. Those 5 grams will give you about a 100 kT explosion.
That gives me an idea for a sci-fi weapon. It squeezes a few grams of stuff into an unstable black hole, which then releases all of the energy in a massive explosion.
If there was a compression ray, it could cause a few pico grams of matter to form a black hole on the surface of the target. If you pulse it very quickly, you get the appearance of a continuous cutting beam. Obviously, those explosions would be very loud and they would emit lots of radiation, so maybe it could be a tank mounted weapon.
That's...... a lot of energy from so little mass
~~I think that might be an underestimate. Mass and energy should be conserved, so if the entire black hole evaporates the total energy output should be E = mc^2^. An A4 page has a mass of 6.25g. c is the speed of light, 299,792,458m/s.~~
~~0.00625kg * (299,792,458m/s)^2^ = 561,721,986,710,511.025J~~
~~The explosion of 1 metric ton (1000kg) of TNT is considered to be equivalent to 4,184 Joules. So 100KT = 418,400,000J. That's not close at all, we're gonna need more TNT:~~
~~561,721,986,710,511.025J / 4,184J/ton of TNT = ~134,254,776,938 tons of TNT.~~
~~Rounding off to significant figures, we're looking at 134 gigatons of TNT. For comparison, the Tsar Bomba, the most powerful nuclear weapon ever tested, had a yield of 50-58 megatons. That's somewhere in the neighborhood of 2,500 Tsar Bombas!~~
~~Maybe this paper folding experiment should be performed away from anything that might be damaged by the explosion. Like, uh, inhabited continents.~~
As pointed out below, I biffed the joules-per-ton-of-TNT thing, sorry!
I think your conversion is off. There's 4,184 joules per gram of TNT, not per ton (https://en.m.wikipedia.org/wiki/TNT_equivalent). Your calculation is off by six orders of magnitude. The first poster's calculation is correct.
Oh damn I think I read this:
And immediately brain farted "gigajoule" to "kilojoule." Thanks!
Make it inhabited planets. But you can stop at planets, no need to search for a new solar system.
AFAIR it follows E = mc^2, so even 5 grams will give you quite a boom.
They might do damage when they evaporate, though, due to the energy release
Evaporate?
Through Hawking Radiation. I believe that idea is still current.
Interesting, thanks
Hawinking radiation does a lot more damage the smaller a black hole gets
The DoD: So you're telling us we should research a black hole bomb?