If for argument’s sake, a black hole the size of a penny or a nickel would suddenly appear in your pocket for whatever reason, you would die, that’s for sure! But why and how? Theoretically, every object can become a black hole if enough pressure is put onto it. Every object in the known universe, including us, you, your cat, a bus, the moon has something that is called a Schwarzschild Radius.
This is a tiny, tiny area of space within which you for example would be compressed into, your density would become so great and your gravity pull so massive that not even light can escape. You would literally be turned into a black hole.
Planet Earth for example, if it were to be transformed into a black hole, would be roughly the size of a penny (8.7 mm or 0.34 inches to be exact). So, if a black hole roughly the size of a nickel would suddenly appear in your pocket, you would basically carry another Earth with you… for a very, very short amount of time. It would consume you so fast, you wouldn’t even know it was happening. And that would not be all. Because of its massive weight, it would travel inside the planet and begin a gravitational dance with Earth, gradually eating the planet from the inside out.
OK, now if that was too obvious, that a black hole the size of a penny would kill you, and every other living being on Earth for that matter, let’s then consider a black hole with the mass of a small coin. If we know that the Schwarzschild Radius for the Earth is roughly the size of a penny, than this radius for a penny is extremely small, right? If we were to compare the size of a Hydrogen atom to the sun, those same proportions would apply to an atom and the Schwarzschild Radius of a penny. Impossibly small!
Now what can a black hole this size do? Not very much you might think, especially given the short life span it would have, due to the Hawking Radiation escaping from it. It would decay the mass it has in 1e-23 seconds. Nothing we can see with the naked eye happens that fast! This of course will not have a happy ending, but instead the energy produced would be equivalent to 3 times the power of the Hiroshima an Nagasaki atomic bombs combined.
Now then, it would be a good idea to stay as far away from them as possible since we can see that even the smallest of black holes can have tremendous energy to give out.
Thanks to the teams at Kurz Gesagt and Vsauce, we were able to bring this funny/scary idea to you. We thank them and hope that you enjoy their videos!