Gravity working … different?

Credit: NASA, N. Benitez (JHU), T. Broadhurst (Racah Institute of Physics/The Hebrew University), H. Ford (JHU), M. Clampin (STScI), G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA

A controversial approach to gravity that challenges Albert Einstein and suggests dark matter doesn’t exist has passed its first test.

The vast majority of physicists agree that gravity acts according to rules laid down in Isaac Newton’s law of gravitation and Einstein’s theory of general relativity. Yet observations of the universe show that the motion of the galaxies can’t be explained by the gravitational pull of all the ordinary matter out there – hence the belief in unseen, dark matter that exerts its own pull.

Now, a team of astronomers studying the distribution of matter in more than 30,000 galaxies say their observations can be explained by an alternative theory that does away with dark matter. If this “modified gravity” is correct, it would up-end hundreds of years of fundamental physics.

Margot Brouwer at Leiden University, the Netherlands, and her colleagues looked at the gravitational lensing of these galaxies – the way they bend the light of more distant galaxies as predicted by Einstein’s theory – to measure their dark matter content.

To their surprise, they discovered the observed lensing could just as readily be accounted for by a new model of gravity, without invoking dark matter. … (New Scientist)

Credit: NASA, N. Benitez (JHU), T. Broadhurst (Racah Institute of Physics/The Hebrew University), H. Ford (JHU), M. Clampin (STScI), G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA

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