If you like cool-sounding science terms, escape velocity should fit the bill. But what the heck does it even mean? Allow me to explain: What goes up, must come down. Surely you've heard this before.

By definition, black holes are objects that ... amount of cleverness will allow something that falls in to escape. Escape velocity is a funny thing: it says that there's a certain amount of ...

But if you want to leave this planet, you have to go faster. This speed is called the escape velocity. It takes a lot of fuel to reach that speed, which is why early rockets, like Apollo's Saturn ...