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/

  • AFK BRB Chocolate
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    103 days ago

    Huh, I’ve always thought that a black hole required a lot of mass, not just a lot of density. Apparently not true?

    • kbal
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      443 days ago

      They can be any mass, it’s density that matters. The smaller ones will not do much damage before they evaporate.

      • @[email protected]
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        303 days ago

        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.

        • @[email protected]
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          11 day ago

          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.

        • Gregor
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          53 days ago

          That’s… a lot of energy from so little mass

          • @[email protected]
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            2 days ago

            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 = mc2. 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!

              • @[email protected]
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                42 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
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              22 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.

      • JackGreenEarth
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        83 days ago

        They might do damage when they evaporate, though, due to the energy release

        • @Cocodapuf
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          2 days ago

          The DoD: So you’re telling us we should research a black hole bomb?