What If a Coin-Sized Black Hole Appeared on Earth?


Supermassive black holes, millions
of times the mass of our Sun, eat stars for breakfast. But how dangerous would
a small black hole be? This is WHAT IF, and here’s what would happen if a coin-sized black hole appeared on Earth. Black holes are extremely dense. They aren’t really holes, but
instead, huge amount of mass. If it was possible for you to create one, you’d have to slam a lot of particles
together in a tiny, tiny space. In practice, if you were able to collapse all the particles of Mount
Everest and create a black hole, that black hole would be
just a few atoms across. Even then, you wouldn’t
want to stand too close to it. For 10 meters (33 feet) around it, the
gravitational pull of that tiny hole would be as strong as gravitational
pull at the Earth’s surface. So what trouble could a
coin-sized black hole cause? The answer depends on
how you define size. Would our hypothetical black
hole be as wide as a coin? Or would it have a coin’s mass? Scenario 1. The black hole
with a diameter of a coin. Looks pretty small, right? Well, because black holes are so dense, this one would be about
the same mass as the Earth. It would also have the gravitational pull one billion billion times
greater than our planet does. But the Earth wouldn’t just
fall into the black hole. Rather, it would orbit it while having chunks
of the planet eaten with every pass. Earth’s rotation would
slow down this banquet, preventing the black hole
from swallowing all of it. Whatever mass of Earth was left, would collapse into a disk of hot rock
and start rotating around the black hole. By that time, the black hole
would have doubled in mass. Surprisingly, it would leave
the Moon unharmed, only causing its orbit to become more elliptical. You wouldn’t be so lucky. The black hole would consume you before
you even realized what was happening. Scenario 2. The black hole
with a mass of a coin. If a five-gram coin suddenly
collapsed into a black hole, that black hole would be terribly tiny. Compared to an atom, it would be as
small as an atom compared to the Sun. And still, it would be terrifying. You see, the smaller a black hole is, the
more Hawking radiation it releases. Simply put, black holes evaporate,
spewing particles back into space. In our case, the black hole
would evaporate way too fast – in just a fraction of a second. Its insignificant mass of five
grams would be converted into a significant 450 terajoules of energy, and cause a massive explosion. That would be like detonating
100,000 tonnes of TNT. The explosion wouldn’t
tear the whole Earth apart, but would affect anything
that happened to be near it. So it would be best if this black
hole-causing coin wasn’t in your pocket. Despite all the technology we’ve invented, humans aren’t able to compress matter
into a black hole even that small. Maybe one day, when space
travel is more widely available, we’ll be able to capture a black hole from
amongst the stars, and learn from it. But that’s a story for another WHAT IF.

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