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Currently Playing: How does a space interferometer work? #shorts

If instead you want to detect the ripples from supermassive black hole mergers, the kinds we find at the centres of galaxies anywhere from a million to 10s of billions of times heavier than the Sun, then you need an interferometer that’s sensitive to the much bigger wavelength, lower frequency gravitational waves given out by orbiting supermassive black holes. It means you need an observatory bigger than the Earth to do this. Which is a huge engineering challenge. But ESA aren’t one to back away from a challenge. So they’re now working towards LISA, the laser interferometer space antenna. The plan is to use the same interference trick as LIGO, but your interferometer is now three spacecraft in a triangle separated by 2.5 million kilometres, all trailing the Earth in its orbit around the Sun, resulting in this amazing triangular dance. Now the technique that LISA will use does differ slightly from ground based detectors like LIGO which use mirrors to reflect the laser beams back along the tunnels so that the split beams interfere with themselves. You can’t do this in space around such a huge triangle though, because by the time the light has travelled 2.5 million km three times, bouncing around each spacecraft, it's too faint to be detected. Instead, LISA will essentially simulate a mirror with each spacecraft creating a new beam with its own lasers, that matches it with the incoming beam, and then send that back out. Construction started on LISA back in July 2025, and the goal is to launch in just under 10 years in 2035. All in the hope of detecting gravitational waves from merging supermassive black holes. Why? Because we think that is a key part of how galaxies evolve and yet we have no direct evidence for it actually happening. 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