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PBS Space Time

PBS Space Time explores the outer reaches of space, the craziness of astrophysics, the possibilities of sci-fi, and anything else you can think of beyond Planet Earth. Host Matt O'Dowd breaks down both the basic and incredibly complex sides of space and time.

Latest episode

Dark Energy Is Driving the Universe Apart. We May Finally Know Why.

Season 11 Episode 22 | 19m 2s | CC

We’ve known since 1929 that the universe is expanding, and since 1998 that it’s speeding up. The unknown force behind this acceleration is called “dark energy,” assumed to stay constant in density. But new evidence hints it may change over time, possibly explaining why major measurements of the universe’s expansion rate don’t agree.