Uploaded March 2026 | Updated September 2026, 2 weeks ago
Lucky for dark matter, the Universe is also expanding. When we look out at distant galaxies they all appear to be moving away from us, because the space itself in between them is getting bigger, spreading out the energy. So in the same way that photons, particles of light travelling through the Universe as an electromagnetic wave, loose energy and have their wavelength stretched out to lower energy light in what's known as a redshift. Dark matter particles also loose energy as the Universe expands, which allows them to cool ever so slightly. So while dark matter doesn't clump together to the extreme to make black holes and stars and galaxies like normal matter does, it instead clumps into big diffuse structures like halos and filaments in the cosmic web. This was actually predicted by computer simulations of the entire Universe containing dark matter back in the 1980s and 1990s, but the cosmic web wasn't observed with telescopes until the late 2010s. So the cosmic web itself, is just yet another piece of evidence in favour of the existence of dark matter in the Universe.
#darkmatter #science #blackhole #drbecky #galaxy #stars
👩🏽‍💻 I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford (Christ Church). I love making videos about black holes, cosmology, dark matter, the early universe, the James Webb Space Telescope, and the biggest unsolved mysteries in astrophysics. 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.
Lucky for dark matter, the Universe is also expanding. When we look out at distant galaxies they all appear to be moving away from us, because the space itself in between them is getting bigger, spreading out the energy. So in the same way that photons, particles of light travelling through the Universe as an electromagnetic wave, loose energy and have their wavelength stretched out to lower energy light in what's known as a redshift. Dark matter particles also loose energy as the Universe expands, which allows them to cool ever so slightly. So while dark matter doesn't clump together to the extreme to make black holes and stars and galaxies like normal matter does, it instead clumps into big diffuse structures like halos and filaments in the cosmic web. This was actually predicted by computer simulations of the entire Universe containing dark matter back in the 1980s and 1990s, but the cosmic web wasn't observed with telescopes until the late 2010s. So the cosmic web itself, is just yet another piece of evidence in favour of the existence of dark matter in the Universe.
#darkmatter #science #blackhole #drbecky #galaxy #stars
👩🏽‍💻 I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford (Christ Church). I love making videos about black holes, cosmology, dark matter, the early universe, the James Webb Space Telescope, and the biggest unsolved mysteries in astrophysics. 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.
