A new research study was published this month claiming to have found smoking-gun evidence for an alternate theory of gravity, called MOND, that doesn’t need dark matter to explain our observations of the Universe. They did the same test that three other research studies have done in the last couple of years, using the same data from the GAIA mission, and somehow all 4 papers have found different results. Some in favour of MOND, and some in favour of our typical theory of gravity: Einstein’s theory of General Relativity. So what is going on here?

Chae (2023; evidence for AQUAL MOND from GAIA) - https://arxiv.org/pdf/2305.04613.pdf
Hernandez (2023; evidence for MOND from GAIA data) - https://arxiv.org/pdf/2304.07322.pdf
PIttordis & Sutherland (2023; evidence for general relativity from GAIA data) - https://arxiv.org/pdf/2205.02846.pdf
Hernandez, Cookson & Cortés (2022; evidence for neither MOND nor general relativity from GAIA) - https://arxiv.org/pdf/2107.14797.pdf

Banik & Zhao (2022; review of all the evidence for MOND) - https://arxiv.org/pdf/2110.06936.pdf
Hernandez, Jiménez & Allen (2012; proposed test of MOND using GAIA data) - https://arxiv.org/pdf/1105.1873.pdf
Bekenstein & Milgrom (1984; first MOND paper) - https://articles.adsabs.harvard.edu/p...

Garret et al. (2021; example model fit using Bayesian statistics) - https://arxiv.org/pdf/2103.08613.pdf

00:00 - Introduction
01:10 - What is this alternate theory of gravity, MOND?
03:58 - How do you use binary stars in GAIA data to test MOND?
07:29 - What results have been found doing this test?
10:29 - Same test, different results - what next? Bayesian statistics
11:42 - Some insider gossip
13:01 - Outro
13:34 - Bloopers

Video filmed on a Sony ⍺7 IV

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👩🏽‍💻 I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford (Christ Church). I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don't know. If you've ever wondered about something in space and couldn't find an answer online - you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars.


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