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Gravitational waves—ripples in the fabric of Einstein's spacetime—that cross the universe at the speed of light have all sorts of wavelengths, or frequencies. Scientists have not yet managed to detect gravitational waves at extremely low 'nanohertz' frequencies, but new approaches currently being explored are expected to confirm the first low frequency signals quite soon. The main method uses radio telescopes to detect gravitational waves using pulsars—exotic, dead stars, that send out pulses of radio waves with extraordinary regularity. Researchers at the NANOGrav collaboration, for example, use pulsars to time to exquisite precision the rotation periods of a network, or array,...

Prof Claudia de Rham’s ‘massive gravity’ theory could explain why universe expansion is accelerating Cosmologists don’t enter their profession to tackle the easy questions, but there is one paradox that has reached staggering proportions. Since the big bang, the universe has been expanding, but the known laws of physics suggest that the inward tug of gravity should be slowing down this expansion. In reality, though, the universe is ballooning at an accelerating rate. Scientists have come up with a name – dark energy – for the mysterious agent that is allowing the cosmos to expand so rapidly and which is...

Supersymmetry and Parallel Dimensions Harvard Physicst Randall among world’s leading string theorists Published On Friday, January 06, 2006  1:00 AM By ADRIAN J. SMITH Crimson Staff Writer Professor of Physics Lisa Randall ’83, recently named one of Newsweek’s most influential people of 2006, rose to the top with her theories on gravity. (Photo credit: CRIMSON/GLORIA B. HO) Professor of Physics Lisa Randall ’83 saw how strong gravity could be during a climbing fall in New Hampshire two years ago. She was performing a “challenging” move when she took a surprising fall, she says. Instead of stopping the fall, her support...