Uploads from Dr. Becky

Currently Playing: Black holes twist spacetime #shorts

Black holes don’t just curve space, they twist it too - dragging it along as they spin. So according to Einstein’s theory of general relativity we can describe gravity mathematically as massive objects curving space itself. And in 1918, two Austrian physicists, Josef Lense and Hans Thirring, were using Einstein’s equations to work out the gravity around a spinning object and realised that curved space gets dragged along by the spinning object. The object doesn’t just curve the space, it adds some spin to the space too. Kind of like spinning something in a thick liquid like honey, the honey at the edge trails behind the middle. This is known as the Lense-Thirring effect, or frame dragging. And this phenomenon isn’t just unique to black holes, Earth does this too as it spins on its axis, dragging space so that satellites make fun spirograph patterns with their orbits. Which is exactly what happens to stars orbiting close enough to the supermassive black hole at the centre of the Milky Way. Like this one, S301. It takes 8.7 years to make one loop of the black hole, travelling at a maximum speed of 25,000 km/s, or 8% of the speed of light, passing as close as 1.78 billion km from the black hole, or just over the distance from Saturn to the Sun. And that means it passes close enough to the black hole to be affected by frame dragging, and we can use it to measure the Milky way’s black hole spin. To get a proper measurement of the Lense-Thirring frame dragging effect, we need to observe how much the orbit of S301 is precessing around. But we’ve only observed half an orbit so far, and to measure the spin we’re going to need at least two complete orbits. So it’s going to be another 10-15 years before we’ve got all the data we need to do this. But over the next decade the GRAVITY collaboration will be keeping a close eye on the centre of the galaxy with the VLTI, but also with the extremely large telescope, the ELT. To find out how they’re going to do just that, check out my latest video over on YouTube, and follow along to find out more about how we know things about space, not just what we know. Video filmed on a Sony ⍺7 IV Video edited by Martino Gasparrini: martino.freelance@gmail.com Video produced by Marina Hui & Dr Becky Smethurst --- 📚 My book, "A Brief History of Black Holes", out NOW in hardback, paperback, e-book and audiobook (which I narrated myself!): http://lnk.to/DrBecky --- 👕 My merch, including JWST designs, are available here (with worldwide shipping!): https://dr-becky.teemill.com/ --- 🎧 Royal Astronomical Society Podcast that I co-host: podfollow.com/supermassive --- 🔔 Don't forget to subscribe and click the little bell icon to be notified when I post a new video! --- 👩🏽‍💻 I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford. 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. http://drbecky.uk.com