Randall Munroe - What If? 2 : Additional Serious Scientific Answers to Absurd Hypothetical Questions

I like ridiculous questions because nobody is expected to know the answer, which means its okay to be confused.

I studied physics in college, so theres a lot of stuff I feel like Im supposed to knowlike the mass of an electron or why your hair sticks up when you rub a balloon against it. If you ask me how much an electron weighs, I feel a little rush of anxiety, like its a pop quiz and Im going to be in trouble if I dont know the answer without looking it up.

But if you ask me how much all the electrons in a bottlenose dolphin weigh, thats a different situation. No one knows that number off the top of their headunless they have an extremely cool jobwhich means its okay to feel confused and a little silly and take some time to look stuff up. (The answer, in case anyone ever asks you, is about half a pound.)

Sometimes simple questions turn out to be unexpectedly hard. Why does your hair stand on end when you rub a balloon on it, anyway? The usual answer from science class is that electrons are transferred from your hair to the balloon, leaving your hair positively charged. The charged hairs repel each other and stick out.

Except... why do electrons get transferred from the hair to the balloon? Why dont they go the other way?

Thats a great question, and the answer is that no one knows. Physicists dont have a good general theory for why some materials shed electrons from their surfaces on contact while other materials pick them up. This phenomenon, called triboelectric charging, is an area of cutting-edge research.

The same kind of science is used to answer serious questions and silly ones. Triboelectric charging is important to understanding how lightning forms in storms. Counting the number of subatomic particles in an organism is something physicists do when modeling radiation hazards. Trying to answer silly questions can take you through some serious science.

And even if the answers arent useful for anything, knowing them is fun. The book youre holding weighs about as much as the electrons in two dolphins. That information probably isnt useful for anything, but I hope you enjoy it, anyway.

What would happen if the Solar System was filled with soup out to Jupiter?

Amelia, age 5

Please make sure everyone is safely out of the Solar System before you fill it with soup.

If the Solar System were full of soup out to Jupiter, things might be okay for some people for a few minutes. Then, for the next half hour, things would definitely not be okay for anyone. After that, time would end.

Filling the Solar System would take about 2 1039 liters of soup. If the soup is tomato, that works out to about 1042 calories worth, more energy than the Sun has put out over its entire lifetime.

The soup would be so heavy that nothing would be able to escape its enormous gravitational pull; it would be a black hole. The event horizon of the black hole, the region where the pull is too strong for light to escape, would extend to the orbit of Uranus. Pluto would be outside the event horizon at first, but that doesnt mean it would escape. It would just have a chance to broadcast out a radio message before being vacuumed up.

What would the soup look like from inside?

You wouldnt want to stand on the surface of the Earth. Even if we assume the soup is rotating in sync with the planets in the Solar System, with little whirlpools surrounding each planet so the soup is stationary where it touches their surfaces, the pressure due to the Earths gravity would crush anyone on the planet within seconds. Earths gravity may not be as strong as a black holes, but its more than enough to pull an ocean of soup down hard enough to squish you. After all, the pressure of our regular water oceans under Earths gravity can do that, and Amelias soup is a lot deeper than the ocean.

If you were floating between the planets, away from Earths gravity, youd actually be okay for a little while, which is kind of weird. Even if the soup didnt kill you, youd still be inside a black hole. Shouldnt you die instantly from... something?

Strangely enough, no! Normally, when you get close to a black hole, tidal forces tear you apart. But tidal forces are weaker for larger black holes, and the Jupiter Soup black hole would be about 1/500th the mass of the Milky Way. Thats a monster even by astronomical standardsit would be comparable in size to the largest known black holes. Amelias souper-massive black hole would be large enough that the different parts of your body would experience about the same pull, so you wouldnt be able to feel any tidal forces.