From Dr. Becky.
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Why doesn’t dark matter collapse? Think about it, gravity pulls on it. There’s a huge amount of it; outweighing all the normal matter in the Universe. So why doesn’t it form dark stars? Dark black holes? Or entire dark galaxies? Instead, it just sits there… in enormous, fuzzy clouds around galaxies. And that’s weird. Because normal matter doesn’t stay fuzzy, it collapses under its own gravity. It makes planets. It makes stars. It makes black holes. And it was after my last video about whether the Milky Way’s centre could be a dark matter cloud instead of a supermassive black hole, many of you asked: "if the dark matter cloud has the same mass, why doesn’t it just collapse?" So what is dark matter doing differently to normal matter…
Similar questions but different:
Is dark matter made of lots of little black holes? (Instead of a particle) – https://www.youtube.com/watch?v=d0wV5frSb6s
Once a black hole forms from normal matter, can dark matter then fall in? – https://www.youtube.com/watch?v=9Qis5VDOd18
The first evidence for a black hole containing some dark matter – https://www.youtube.com/watch?v=QeNspAwdgRY
00:00 Introduction
02:40 Why normal matter collapses under gravity in the first place
06:56 The crucial reason why dark matter can’t
10:01 Bloopers
Video filmed on a Sony ⍺7 IV
Video edited by Martino Gasparrini: https://www.fiverr.com/mgs_editing
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🎧 Royal Astronomical Society Podcast that I co-host: podfollow.com/supermassive
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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.
