2 posts tagged with "space"

There's a question the physicist Enrico Fermi supposedly blurted out over lunch in 1950, somewhere between the soup and the punchline of a joke about flying saucers. The galaxy is old — around 13 billion years. It's enormous — hundreds of billions of stars, a large fraction with planets. Even at sluggish, sub-light speeds, a single expansionist civilization could colonize the whole thing in a few tens of millions of years. That's a rounding error on cosmic timescales.

When we think about advanced civilizations, we tend to imagine spaceships, floating cities, or omnipresent artificial intelligences. But in 1964, the Soviet astronomer Nikolai Kardashev proposed a far more elegant — and far more physical — way to classify a civilization's progress: the amount of energy it is able to harness.