On May 10, 2009 a pair of gamma-ray photons reached the Fermi Gamma-Ray Space Telescope only 900 milliseconds apart after traveling for 7 billion years. Fermi’s measurement gives us rare experimental evidence that space-time is smooth as Einstein predicted, and has shut the door on several approaches to gravity where space-time is foamy enough to interfere strongly with light.
發表於 2011-8-3 12:09:07
