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The universe has billions of galaxies and billions of stars, so why is space dark?

John E. Mortensen, Easton, Pennsylvania
hubble ultra deep field
Called the Hubble Ultra Deep Field, this galaxy-studded view represents a core sample of the universe.
NASA, ESA, and S. Beckwith (STScI) and the HUDF Team
At 13.7 billion years, the universe is old but not infinitely so, and stars themselves have finite life spans.

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