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xkcd #3033: Origami Black Hole (xkcd.com)

submitted 3 days ago by [email protected] to c/xkcd

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You may notice the first half of these instructions are similar to the instructions for a working nuclear fusion device. After the first few dozen steps, be sure to press down firmly and fold quickly to overcome fusion pressure.

https://explainxkcd.com/3033/

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[–] [email protected] 13 points 3 days ago* (last edited 3 days ago) (2 children)

~~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!

[–] reattach 6 points 3 days ago* (last edited 3 days ago) (1 children)

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.

[–] [email protected] 4 points 3 days ago

Oh damn I think I read this:

The ton of TNT is a unit of energy defined by convention to be 4.184 gigajoules (1 gigacalorie),[1] which is the approximate energy released in the detonation of a metric ton (1,000 kilograms) of TNT.

And immediately brain farted "gigajoule" to "kilojoule." Thanks!

[–] marcos 2 points 3 days ago

Like, uh, inhabited continents.

Make it inhabited planets. But you can stop at planets, no need to search for a new solar system.