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BOB HIRSHON (host):
Is the Universe losing weight? I’m Bob Hirshon and this is Science Update.
Fourteen-year-old Science Update listener Ibrahim emailed to ask if our expanding universe is stretching out the curved fabric of space-time, and if that’s weakening gravity. A heady question that we put to astrophysicist David Lindley.
DAVID LINDLEY (Astrophysicist and author):
In the most straightforward models, with an expanding universe, as it expands the space-time curvature gets smaller and the expansion actually slows down.
HIRSHON:
But modern observations show that the expansion is actually speeding up, as a result of what physicists call “dark energy.” And how that affects gravity at these huge scales is still a mystery. But Lindley says the expanding universe has little effect locally, and doesn’t alter the gravity or the distance between local stars, planets, and we curious humans. I’m Bob Hirshon, for AAAS, the science society.
Story by Bob Hirshon