There is a mismatch between two ways of measuring galactic mass. Dark matter is one way to solve it, but so is rewriting the laws of gravity, says Chanda Prescod-Weinstein


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3 March 2021

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ESA/Hubble & NASA, R. Tully; ack

I’VE been giving a lot of talks about my research to a range of scientific audiences of late. The listeners range from groups that are mainly undergraduates to those made up of specialists in my field – in other words, people who are also searching for and trying to understand the behaviour of dark matter.

In nearly all of these presentations, I start by explaining Vera Rubin and Kent Ford’s observations of galaxies. These showed that there was a mismatch between their measurements of galactic masses and what one might expect the mass to be …