Listening for Gravity Waves, Silence Becomes Meaningful

Photo: ARMED FOR DISCOVERY: At the LIGO site in Louisiana, a pair of four-kilometer-long arms [one of which stretches toward the top of this photograph] awaits the telltale elongation or compression of a passing gravity wave. A similar observatory in Washington State is also on the case. LIGO Scientific Collaboration

From Scientific American:

The ripples in spacetime predicted by general relativity remain one of the most sought-after prizes in physics, and new research narrows estimates of their prevalence.

Gravity waves spread through space and time like ripples on a pond, warping the fabric of the universe as they pass. The largest waves emanate from the most cataclysmic events in the universe: stellar explosions, mergers of black holes, and the violent first moments of cosmological history. Or so the venerable theory of general relativity goes—although many predictions of Albert Einstein's theory of gravity have been proved, only indirect evidence for gravity waves has been found.

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Gravity Wells Could Provide 'Parking Lots' For Spaceships

From McClatchy News:

WASHINGTON — Nature has provided five huge rest stops far out in space for the convenience of spacecraft traveling from Earth.

Some NASA folks call them "parking lots" in space.

They're unusual locations where gravity loses its pull and a spaceship can loiter, rather like a marble at the bottom of a cup, without using a lot of fuel. Three of them are 930,000 miles outside Earth's orbit. One is between the Earth and the sun, and another is hidden on the far side of the sun.

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