Mar 11, 2026 · 42 min · 11 segments
Welcome to Voices of Mathematics, a podcast from the Mathematics Faculty at the University of Cambridge. From number theory and geometry to cosmology and quantum physics, join us to explore topics…
Ulrich SperhakeGuest
Seppe StaelensGuestMarianne FreibergerHostRachel ThomasHostSo as Uli said, gravitational waves are ripples in the very fabric of space-time itself.
So as they distort space-time, they actually distort the distances that we experience.
So it's really fascinating how experiments like LIGO detected these using something called laser interferometers.
They have these massive L-shaped detectors where each side of the L is four kilometers long and there's a mirror at the end of each side of the L.
And as the gravitational waves distort spacetime, they slightly distort the distances between the mirrors and the corners of the L.
And these detectors are so sensitive that they can detect even the smallest distortion in the length of these parts of the laser interferometer.
Azuli mentioned there's a connection between gravitational waves and black holes.
so black holes, as most people probably know, they are objects that are extremely massive and dense so that light can't actually escape from their vicinity.
People already knew that gravitational waves were going to be weak because in order to create them, you need something very heavy, very extreme, like a black hole, like a neutron star.
And most people will be aware that something like a black hole and neutron star doesn't live very close to us because we don't see any of them around.
which means that these waves that are already small from the beginning have to travel these far away distances.
Yeah, so the gravitational waves originate from indeed supposed two black holes or two neutron stars orbiting around each other.
exactly like the the earth and the sun um but when they while they're doing this they lose energy so this this wasn't uh present in the original theory by by kepler and by newton and so on they lose energy this energy is what generates the waves and um for newton stars and black holes because they're so compact so so small A neutron star, for example, has a radius of about 10 kilometers, so a bit like a large city, but it's as heavy as the sun.
Because they're so compact, so small yet so massive, they can get really close to each other without actually colliding.
And it's at these points that they're going through such a violent... dancing motion around each other when they actually manage to emit these strong gravitational waves.
And the waves get increasingly stronger and stronger and stronger until they actually touch, actually collide, then there's a cataclysmic collision, and then the emission of gravitational waves stops again because the dance, this merger has finally happened.
So as Uli said, gravitational waves are ripples in the very fabric of space-time itself.
So as they distort space-time, they actually distort the distances that we experience.
So it's really fascinating how experiments like LIGO detected these using something called laser interferometers.
They have these massive L-shaped detectors where each side of the L is four kilometers long and there's a mirror at the end of each side of the L.
And as the gravitational waves distort spacetime, they slightly distort the distances between the mirrors and the corners of the L.
And these detectors are so sensitive that they can detect even the smallest distortion in the length of these parts of the laser interferometer.
Azuli mentioned there's a connection between gravitational waves and black holes.
so black holes, as most people probably know, they are objects that are extremely massive and dense so that light can't actually escape from their vicinity.
People already knew that gravitational waves were going to be weak because in order to create them, you need something very heavy, very extreme, like a black hole, like a neutron star.
And most people will be aware that something like a black hole and neutron star doesn't live very close to us because we don't see any of them around.
which means that these waves that are already small from the beginning have to travel these far away distances.
Yeah, so the gravitational waves originate from indeed supposed two black holes or two neutron stars orbiting around each other.
exactly like the the earth and the sun um but when they while they're doing this they lose energy so this this wasn't uh present in the original theory by by kepler and by newton and so on they lose energy this energy is what generates the waves and um for newton stars and black holes because they're so compact so so small A neutron star, for example, has a radius of about 10 kilometers, so a bit like a large city, but it's as heavy as the sun.
Because they're so compact, so small yet so massive, they can get really close to each other without actually colliding.
And it's at these points that they're going through such a violent... dancing motion around each other when they actually manage to emit these strong gravitational waves.
And the waves get increasingly stronger and stronger and stronger until they actually touch, actually collide, then there's a cataclysmic collision, and then the emission of gravitational waves stops again because the dance, this merger has finally happened.
The rest of this transcript — segmented and speaker-labeled, so you land on the exact moment something was said
Search every transcript — by keyword, by phrase, or by meaning, across every show Radar indexes
Trends — what is surging across podcasts, measured against its own baseline
Alerts — when a name you follow appears in a newly indexed episode
No account is needed to search Radar.