This mysterious energy is everywhere. Scientists still don't know what it is

The universe — everything in existence — is expanding every second! It's only been about a hundred years that humanity has known this, too — that most galaxies are traveling away from us and the universe is expanding. Just a few decades ago, in the late 1990s, scientists started to notice another peculiar thing: The expansion of the universe is speeding up over time. It's like an explosion where the debris gets faster instead of slowing down. The mysterious force pushing the universe outward faster and faster was named dark energy. Cosmologist Brian Nord joins host Regina G. Barber in a conversation that talks about what dark energy could be and what it implies about the end of our universe.

Curious about other happenings in our universe? Email us at shortwave@npr.org.

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Today's episode was produced by Hannah Chinn and edited by Rebecca Ramirez. They both checked the facts. Kwesi Lee was the audio engineer.

Special thanks to our friends at the U.S. Space & Rocket Center, Home of Space Camp®.