Everyone knows that relativity plays hell with time, and that it can do a number on space, but what about mass? Why do objects get more or less mass depending on their relative speed? We're going to give you a quick explanation of why running can make you gain weight. No, we don't think it's fair either.

Planning a little space travel to see some friends on Kepler 22b? Thinking of trying out your newly-installed FTL3000 Alcubierre Warp Drive to get you there in no time? Better not make it a surprise visit - your arrival may end up disintegrating anyone there when you show up.

Special and general relativity help us see time, space, and energy in strange new ways. That strangeness seems to remove the theories from our everyday experience. Despite their exotic appeal, Einstein's famous theories are part of our everyday life. Find out how you depend on special and general relativity to find…

This truly awesome video has the answers to that question. It imagines a trip down a desert highway at speeds approaching light, and then shows all the weird and wonderful optical effects the theory of special relativity says we'd experience.

There's been a lot of hubbub about the possibility of FTL neutrinos. But would breaking the light barrier really be such a big deal? Hell, yes, it would! In this week's "Ask a Physicist," we'll find out why.

A week ago, who among us would have guessed that light, the universe's ultimate speed demon, would be observed getting outpaced by a bunch of reckless neutrinos? Yes, these observations will obviously need to be checked and rechecked, but it just goes to show that you rarely know as much about something as you think…

Do you want your share of scientific immortality? You can devote your life to mastering your field, examining the mysteries of the universe, and then finally arriving at one great discovery...but according to Stigler's Law, you won't get the credit.

Gravity forces galaxies that are relatively close together to form clusters, which in turn form superclusters between vast stretches of cosmic void. But now there's an even bigger level of organization...and we have no idea how to explain it.

General relativity and quantum mechanics are the twin foundations of modern physics, but there's a problem: they're mutually exclusive, at least according to our current understanding. A new model using loop quantum gravity might have the beginnings of a solution.

Einstein's theory of relativity says that time passes more slowly the closer you get to the ground, because you're closer to Earth's gravitational field. It's a tiny difference, but big enough for a pair of laser-powered clocks to actually measure.