14:13
In space, no one will hear your scream. This is a famous expression from the movie Alien. A good movie, by the way. Less so, you know what the point is. Space is a nail. There are no molecules there that could carry sound. Basic physics for eighth grade. Well, maybe that's not the case anymore, given the state of our education. But I digress. For decades we have been fed the idea that the universe is a realm of absolute dead silence, where not even a supernova is a speck of sand. Unless it's on TV, of course, then they add a loud explosion sound, but either way, listen to this. This is such a really creepy sound, like something straight out of a horror movie. A thousand damned souls screaming from the depths of hell.
But no, it wasn't created by a sound designer. These are real pressure waves passing through the superheated gas of the Perseus cluster, ejected above a massive black hole. Scientists extracted these waves from X-ray data collected by the Chandra Observatory and then raised them 57 octaves, which raises the obvious question: How, baby, can there be sound in a vacuum? Okay. Yes. And in an absolute vacuum, there is no medium for the transmission of sound waves. If you were in outer space without a spacesuit, you would die in silence. But there is one nuance.
Not all space is empty. Surrounding this particular black hole is a massive cloud of superheated intergalactic gas. This active black hole blows giant bubbles into this gas, sending pressure waves radiating out in all directions. This is the sound. True, it has a very low frequency. And when I say low, I mean really low. It is so low that one complete cycle takes about 9.6 million years. Of course, if we were flying right there, we wouldn't hear anything at all. Our ears are simply not designed for such frequencies, and the density of the gas is too low for human hearing. And, by the way, this rumble is n't just there for the spooky atmosphere.
These waves pull energy away from the center of the cluster, which constantly heats the gas. and, interestingly, it doesn't allow it to cool down properly. So it's not just about making creepy sounds, it's also about pumping enough energy into the surrounding gas to keep it hot. Okay. But before we continue, I want to make one important, quite important clarification. Not every sound we hear today is real in the usual sense. In the case of Perseus, we're talking about real pressure waves, just raised to the range of our hearing. With comets and planets, instruments can measure fluctuations in plasma or magnetic fields, which we then convert into audio. And sometimes scientists go
even further and assign pitch, loudness, and timbre to primary data that was never sound to begin with. Technically, this is all called sonification. The essence of the difference lies in the several stages of processing that this data must go through before it becomes sound. Okay, let's go. And maybe turn up the volume a little if you care about your ears. Comet 67P, better known as Comet Churyumov Gerisymenko. In 2014, the European Space Agency and their Rosetta spacecraft finally caught up with it after 10 years in space. You might be wondering what's going on here. It's just a giant, pointless chunk of dirty ice and dust the size of a small mountain hurtling through the void.
It should be completely dead and quiet. But as soon as the spacecraft got closer, it turned on its magnetometers and recorded this. It is a bit like the flight of a bumblebee, but less so that scientists have given it a good name. Comet song. Well, okay, why not? But how does this lumpy, dirty ball of ice even make such a strange sound? The comet's nucleus does not create its own magnetic field, but as the comet approaches the sun, it ejects neutral gas into space. Ultraviolet light then ionizes this gas, and these freshly charged particles begin to interact with the solar wind. As they move through the magnetic field carried by this wind, they create an electric current. This current becomes unstable. The field
begins to oscillate and voila, the comet begins to sing. Rosetta captured these waves at a frequency of about 40-50 MHz. The human ear, of course, can't pick this up, so the guys at EC raised the frequency by about 10,000 times, adapting it to our hearing range. And here, please, a creepy alien ambiance from a big piece of space. ice. Okay, Jupiter, this planet is huge, you already know that. But what really sets it apart is its magnetic field, the strongest of any planet in the solar system. As the Jer1din battle approached Epiter, it crossed what is called the main shock wave. This is the boundary where the solar wind at superspeed crashes into Jupiter's magnetic bubble. And this is what this collision sounds like.
This is a really annoying sound. It could be on repeat if I wanted to make fun of someone. Either way, that annoying screeching is the noise of plasma right on Jupiter's main shock wave. essentially at the very edge of its magnetosphere. The solar wind, which is simply traveling through the system, suddenly has to slam on the brakes. It contracts, heats up, and is forced to go around Jupiter's magnetic bubble. And all this raging plasma turbulence gives us a sound like a million fingernails scratching on a kilometer-long school board. And then comes Saturn. We are all used to admiring photos of his luxurious rings. NASA's Cassini spacecraft, which spent nearly 20 years in space, 13
of which explored Saturn, began its final months in 2017. But before deliberately burning it in Saturn's atmosphere, controllers directed the spacecraft into a series of dives through the gap between the planet and its nearest rings. Before the first dive, the engineers had no idea how much debris was flying in that gap. So they turned Cassini around and pointed its large four-meter communications dish forward like a shield, then braced themselves for a real cosmic hail. Hmm, well, that didn't happen. It turned out that the space between Saturn and its rings is actually very empty, which is why the team called it the great void. Then later, as Cassini glided along the inner edge of the D ring, the silence ended. Listen here.
So, the rings are made up of rocks, ice, and tiny microscopic dust particles. And from the box protruded three antennas 10 m long, connected to a device called RPWS abort. Okay. No, I'm not kidding. They didn't call him that. It doesn't read like a word at all. It's just a boring acronym that stands for Scientific Instrument for the Study of Radio and Plasma Waves. So, when these tiny wormholes crashed into the Cassini and its antennas at breakneck speed, they instantly turned into tiny clouds of plasma, and each collision created a brief electrical pulse. This is the clicking sound we just heard. And this part is actually a bit sad when
you remember where Cassini was headed to meet his demise. These were some of the last audio portraits the Probe sent back to Earth after nearly 20 years in space. And the strangest thing is that Cassini was still working, but NASA had a very good reason for destroying this very real spacecraft. He was running out of fuel and eventually they wouldn't be able to control where he would go. So they intentionally sent it into Saturn's atmosphere to burn up. And to be absolutely sure that it will never accidentally hit wenceslate or titanium and contaminate them with terrestrial microbes. Okay. Now we are going beyond our solar system. So, pulsars. They are really, really cool. At least, these are some of my space favorites.
Pulsars are the corpses of giant stars. More precisely, it is a type of neutron star. Neutron stars are incredibly dense stellar remnants left over from supernova explosions. But in the case of pulsars, as they rotate, they emit these super-powerful beams of radiation. Sounds like the most annoying smoke detector in the world. So, normally when a pulsar ages, it loses energy and slows down. But interestingly, some of them may get a kind of acceleration. A second wind, if you will, when there is a companion star nearby. I mean, if it's part of a dual system. This is when two stars are gravitationally bound to each other. A pulsar can literally suck matter out of its partner and use this extra
mass to spin up again. The fastest one we know of spins 716 times per second. At this speed, when we convert impulses into sound, you will no longer hear individual beats. 716 pulses every second merge into an almost continuous tone. I would turn it on for you, but unfortunately the signal is too weak to make a good sound from it. Anyway, finally my favorite pulsar is Sail, because, you know, it has such a cool funky rhythm. In short, with pulsars, I think you get the point. The rotation sets the rhythm, but the next sound is completely, completely different. It does not come from radio waves. This time, space itself vibrates. Two black holes, each tens of times more massive than our sun, orbit each
other faster and faster until they eventually merge into a single black hole. And when they do, they send out gravitational waves that ripple through space-time. It's not something moving through space, it's space itself going in ripples. And back in 2015, a project called LGO first recorded one of these waves. Essentially, LIGO is two huge, hippo-like observatories. One in Washington and the other in Louisiana. We call them observatories. And technically it is. But it's not what you usually imagine. These are small domes with telescopes pointing into the very sky. They're actually these huge, weird buildings in the shape of the letter G. So each one has shoulders that diverge like this. Each arm is 4 km long and
laser beams travel back and forth inside them. Do you understand? Okay. So when a gravitational wave passes through the earth, it slightly stretches one of these arms while simultaneously compressing the other. And in a split second they switch places. What is stretched is compressed, and what is compressed is stretched. So the two laser beams travel slightly different distances. And when the laser beams converge again, they are only a tiny, tiny, tiny fraction out of sync. LIGO can actually measure this incredibly tiny difference. During that first detection, the distance between the two arms changed by only about four quintillionths of a meter. That's about 12 times the diameter of a proton. And we were able to
measure it. In general, here's what it captured. Sounds like a leaking faucet, doesn't it? This signal lasted only about two- tenths of a second, but in that very short time, a mass equal to about three of our suns was converted into gravitational wave energy. And, by the way, this little lump needed almost no adaptation. The frequency was already within our hearing range. So he didn't have to invent a voice or raise his pitch a thousand times or anything like that. They just took this signal and essentially connected a speaker to space-time itself. This LIGO signal, by the way, traveled 1.3 billion years to reach us. But now we will delve much further into the past, almost to the very beginning of the universe. About 380,000 years after the
big bang, the universe cooled enough that these electrons were able to attach to atomic nuclei and stopped obstructing light. And when that happened, light was suddenly able to travel freely through space. And this ancient light still exists today. In fact, it comes towards us from almost every direction in the sky. This is what we call cosmic microwave background radiation. So how did we find out about this? Back in 1964, two radio astronomers, Arnop Penzias and Robert Wilson, were working with this huge horn antenna at Bellabs. And they kept introducing this weird annoying background noise. They check the equipment, recalibrate the receiver, even scrape bird droppings off the antenna itself, thinking that
the problem is there, but it doesn't help. It turned out that they accidentally stumbled upon the same cosmic microwave background radiation. In essence, they discovered the oldest light in the universe, an echo left over from the big bang. Years later, physicist John Kremer takes these incredibly precise measurements of tiny fluctuations in the cosmic microwave background radiation and uses them to reconstruct what these primordial waves might have sounded like. The universe is filled with this dense, superheated plasma. No stars, planets, or anything we know today. But this plasma can actually carry a pressure wave, real sound waves. So Kramer takes the pattern that these waves left in the relic background, converts
that data into sound, and then boosts the frequencies by about 10 to the 26th power so that our ears can hear it. And we get this. Cool sound. You can hear the tonality seem to slide down in the process. This is no coincidence. In fact, Kramer intentionally built this collapse into the reconstruction, because as the universe expanded, these huge pressure waves stretched along with it. Their wavelength became longer and their frequency lower. So, the universe cools, the plasma turns into a neutral gas, and these sound waves stop propagating. But here's the coolest thing.
The waves themselves disappear, but the pattern they create does not. Those primordial sound waves left a measurable structure in the universe itself. And this structure still exists. So we can still see the imprints of sound waves that were moving through the universe before the first stars appeared. By the way, do you remember the old analog TVs? Maybe some of you serious retro gamers even still have them. Anyway, you know that snow on the screen when you turn on the work channel. Most of this snow is caused by everyday things like the TV itself, radio interference, and all sorts of other junk. But about 1% actually comes from cosmic microwave background
radiation. That is, when you look at a non-working TV or TV channel, you are literally looking at radiation left over from the very early universe. You see a kind of afterglow from the beginning of everything, before the first stars even appeared. I think that's very cool. So yes. Scream into a vacuum and no one will hear you. But that doesn't mean the universe is actually silent. We have pressure waves around black holes, magnetic oscillations of plasma around comets, radio pulses from dead stars, and gravitational waves that literally stretch and compress spacetime itself. For the most part, these things never reach
our ears like regular sound, but we've learned to detect them, measure them, translate them, and essentially connect the entire universe to our home entertainment system. Okay. Enough cosmic noise for today. Please subscribe to the channel, click the bell, and give more likes. See you in the next video.
