Alternative theory of gravity makes a nearly testable prediction

Alternative theory of gravity makes a nearly testable prediction

Enlarge / Galaxy clusters generated by the Universe simulator IllustrisTNG. (credit: TNG Collaboration)

From our current perspective, the Universe seems to be dominated by two things we find frustratingly difficult to understand. One of these is dark matter, which describes the fact that everything from galaxies on up behaves as if it has more mass than we can detect. While that has spawned extensive searches for particles that could account for the visual discrepancy, it’s also triggered the development of alternative theories of gravity, ones that can replace relativity while accounting for the discrepancies in apparent mass.

So far, these proposals have fallen well short of replacing general relativity. And they say nothing about the other big mystery, dark energy, which appears to be accelerating the expansion of the Universe. Instead, researchers have developed an entirely separate class of theories that could modify gravity in a way that eliminates

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Space-based gravitational-wave detector may detect strange exoplanets

Space-based gravitational-wave detector may detect strange exoplanets

Enlarge / A depiction of one of the trio of satellites that will form the Laser Interferometer Space Antenna. (credit: NASA)

The first detection of gravitational waves came via an instrument that has to strain to overcome the constant background of vibrations and jolts that occur on Earth. Its success has helped push for the pursuit of a project that would rise above all that noise. LISA—the Laser Interferometer Space Antenna—would detect gravitational waves using the same technique as LIGO but place its hardware in space, free of any ground-based vibrations. Preliminary tests of prototype hardware has found that the idea should work.

LISA isn’t expected to be put in place until the 2030s, but that hasn’t stopped astronomers and physicists from contemplating the things that it might possibly detect. Two of these astronomers, Nicola Tamanini and Camilla Danielski, are now suggesting that LISA could be used to identify

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