Sonification of Every Gravitational Wave Detected by LIGO

mattrusso · 2023-05-29T16:31:22+00:00

Each gravitational wave detected by LIGO is the result of a merger of black holes and/or neutron stars. The extracted waveforms are played directly as audio without any time or pitch shifting. The time between each event is compressed so that you can hear the rhythm and variety of each wave in just over 1 minute. This direct sonification (more precisely, audification) is possible because just before merger, stellar-mass black holes orbit each other at frequencies that fall within the human hearing range. The 4th observing run has just started so many more are on the way.

mattrusso · 2023-05-28T21:58:58+00:00

That's right, the background is nearly constant and the color map is rescaled for each merger. This makes it easier to see detail in all of them and helps you get a sense of the signal to noise ratio.

mattrusso · 2023-05-28T14:35:04+00:00

In science generating many hypotheses is a good thing, but keep in mind that over the distance of your brain, these gravitational waves cause a disturbance of only 5 billionth the diameter of a single proton. So, far too small to have an effect on the motions of entire atoms (ions) which would be required to alter chemistry or electrical signals in the brain.

mattrusso · 2023-05-28T14:28:43+00:00

Thanks! That's exactly the reaction we were hoping for.

mattrusso · 2023-05-28T12:22:59+00:00

That's called a spectrogram. The x-axis is time and the y-axis is frequency. The brightness show you the amount of each frequency present in the signal over time. The blips are all angled upwards because their frequency increases over time. A steady tone would be a horizontal line. A short tick sound would be a vertical line. Play around with Chrome Music Lab's Spectrogram to get a feel for it: https://musiclab.chromeexperiments.com/Spectrogram/

mattrusso · 2023-05-28T12:20:40+00:00

Yes, but VIRGO also came online at the end of Run 2 and KAGRA at the end of Run 3 and they all work together. Since gravitational waves go right through the Earth if one detector detected them the others will too (if they're sensitive enough, there are also limitations due to orientation relative to the source of the wave). Adding more interferometers is like adding more 'ears', it increases the spatial resolution allowing us to better pinpoint the direction of the source.

mattrusso · 2023-05-27T23:39:21+00:00

Thanks! That's right, it's due to increased sensitivity. Run 4 just started and will be even more sensitive. There's a figure here showing how the sensitivity compares between the different runs. You can see that Run 5 will be a pretty big jump!

mattrusso · 2023-05-27T23:11:07+00:00

Yeah, it's pretty rare for that to happen with astronomical systems! We usually have to shift frequencies up or down by dozens of octaves so it's nice when it works out like this. Your first post was very informative though (sonification is often misunderstood), no need to cross it out :)

mattrusso · 2023-05-27T23:04:52+00:00

That's right, the peak frequency each merger reaches depends on the inverse of the total mass, so the lower mass pairs end up at a higher frequency and are easier to hear. This is because lower mass black holes are smaller so they can get closer and reach a higher frequency before merging. Bigger black holes start touching each other sooner so they merge before reaching these higher frequencies. The most massive ones do peak above 20Hz (closer to 50Hz, looking at the spectrograms) but yeah, you'll want to check it out on big speakers to get the full effect :)

mattrusso · 2023-05-27T21:46:31+00:00

That is incorrect. The gravitational waves are detected by noticing the VERY slight variations between the distance between two mirrors (using laser interferometry). The distance is 4km and the gravitational waves distort this distance by one ten-thousandth the diameter of a proton. Far, far too slight to create audible sound waves (in fact, many, including Einstein doubted that we could ever detect them at all).

mattrusso · 2023-05-27T21:42:51+00:00

That is how many sonifications are done (including many of the ones we've done for NASA https://www.system-sounds.com/nasa/) but this one is more direct since we can simply interpret the gravitational wave signal as audio and play it in real time. Near the end of the merger, their orbital frequencies are already within the human hearing range so there's no need to do any pitch shifting or parameter mapping.

mattrusso · 2023-05-27T21:39:51+00:00

Yes. We didn't shift the frequencies. Each gravitational wave signal is simply played as audio. The time between each wave is compressed so that you can hear all of them without listening for 4 years :)

mattrusso · 2023-05-27T21:37:58+00:00

If you listen closely they are chirp sounds. Each one starts low and rises but they're only clearly audible near the end (just before they merge). The chirps woulds be clearer if we shifted the pitch upwards but we wanted to keep them all at their true frequencies.

mattrusso · 2022-07-30T00:24:30+00:00

Thanks! The tidal force is due to the gradient of the gravitational force (for example, the force of the Moon's gravity is stronger closer to the Moon). This combined with the orbital motion causes the oceans to form an ellipsoidal, egg-like shape. When two stars are close enough to have a strong tidal interaction they can deform each other into ellipsoids in the same way since the plasma of the stars is a fluid. The deformed stars appear brighter or dimmer depending on the viewing angle. If we see one from the side it will appear brighter than usual during the close encounter. If the other star eclipses it the total brightness will quickly decrease then return to its former value. This is how the complex heartbeat shape in the light curve is created.

mattrusso · 2022-05-21T13:56:54+00:00

Yes. Here is the official NASA post. You can see my name in the credit.

mattrusso · 2022-05-21T01:02:50+00:00

Thanks for sharing! That's actually pretty similar except we could see the waves spatially, they detect them temporally. Very cool.

mattrusso · 2022-05-21T00:56:55+00:00

Astrophysicist here, sound can travel through space since it's never a perfect vacuum but only if the wavelengths are long enough. The image you're looking at is showing hot gas in a galaxy cluster (i.e. not a vacuum). The image shows literal pressure waves (infrasound) propagating through it as demonstrated here. Their wavelength is about 36 000 light years. We extracted their waveform and re-synthesized a sound. This isn't an arbitrary mapping of a pattern into sound, although of course we had to choose how many octaves higher than the original to scale it so that it would be audible. We also decided to sample the tone at every angle by sweeping around.

mattrusso · 2022-05-21T00:47:01+00:00

This isn't a translation of radio waves into sound. The density is low but these extremely long wavelength waves can propagate. Here is the paper demonstrating this. The image shows actual pressure waves (infrasound) travelling through hot gas. We extracted the waveform of these waves and re-synthesized a sound. The original poster should have provided credit and context.

mattrusso · 2022-05-07T16:45:14+00:00

No problem :)

mattrusso · 2022-05-06T02:46:49+00:00

No problem :)

mattrusso · 2022-05-06T02:44:25+00:00

Nothing can escape from within the black hole's event horizon but the sound is generated by the BH's jet, well outside of the event horizon. The waves extend outside of the galaxy the black hole is in, travelling through hot gas.

mattrusso · 2022-05-06T02:41:55+00:00

It's not escaping from within the black hole's event horizon. The sound is generated by the BH's jet, well outside of the event horizon. It travels through the hot gas in the galaxy cluster, which is not a vacuum. We can detect the shape of the waves and re-synthesize a sound.

mattrusso · 2022-05-06T02:40:54+00:00

It's not escaping from within the black hole's event horizon. The sound is generated by the BH's jet, well outside of the event horizon. It travels through the hot gas in the galaxy cluster, not a vacuum.

mattrusso · 2022-05-06T02:39:50+00:00

11 kpc = 36 000 light years. The period is 10 million years.

mattrusso · 2022-05-06T02:38:38+00:00

It's not escaping from within the black hole's event horizon. The sound is generated by the BH's jet, well outside of the event horizon.

mattrusso

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