The sound required a lot of “bumping up.” The “note” emitted by the black hole was increased by 57 octaves in order to make it audible to the human ear. “For reference, the A in the middle of the piano is 440 cycles per second, and this [sound] is one cycle per 10 million years,” Blazek says.
As NASA explained it back then, "Astronomers discovered that pressure waves sent out by the black hole caused ripples in the cluster's hot gas that could be translated into a note — one that humans cannot hear some 57 octaves below middle C." To us, it just sounds like a beginning of a very sinister dubstep track.
"The misconception that there is no sound in space originates because most space is a ~vacuum, providing no way for sound waves to travel," the NASA team said. "A galaxy cluster has so much gas that we've picked up actual sound. Here it's amplified, and mixed with other data, to hear a black hole!"
The viral audio, to be clear, is not a recording: it has been produced by 'sonifying' data taken from NASA's Chandra X-ray Observatory (another space telescope). The audio produced was originally 57 octaves below middle C, which meant the frequency had to be raised 'quadrillions' of times to be heard by human ears.
(Photo by NASA/CXC/Columbia Univ./C. Hailey et al.) For the first time in history, earthlings can hear what a black hole sounds like: a low-pitched groaning, as if a very creaky heavy door was being opened again and again.
The noise is created by pressured waves coming from the black hole which caused ripples in the hot gas, and is 57 octaves below middle C, meaning scientists had to raise the frequency to make it audible to humans.
The loudest sound in the universe definitely comes from black hole mergers. In this case the “sound” comes out in gravitational waves and not ordinary sound waves.
Anything outside this surface —including astronauts, rockets, or light—can escape from the black hole. But once this surface is crossed, nothing can escape, regardless of its speed, because of the strong gravitational pull toward the center of the black hole.
Black holes have two parts. There is the event horizon, which you can think of as the surface, though it's simply the point where the gravity gets too strong for anything to escape. And then, at the center, is the singularity. That's the word we use to describe a point that is infinitely small and infinitely dense.
Stellar black holes are very cold: they have a temperature of nearly absolute zero – which is zero Kelvin, or −273.15 degrees Celsius. Supermassive black holes are even colder.
Astronomers have discovered two new black holes that are the closest ones to Earth known, and also represent something that astronomers have never seen before. The black holes, designated Gaia BH1 and Gaia BH2, were discovered in data collected by the European Space Agency's (ESA) Gaia spacecraft.
As black holes evaporate, they get smaller and smaller and their event horizons get uncomfortably close to the central singularities. In the final moments of black holes' lives, the gravity becomes too strong, and the black holes become too small, for us to properly describe them with our current knowledge.
For this reason, black holes are considered an edge of space, a one-way exit door from our universe; nothing inside a black hole can ever communicate with our universe again, even in principle.
Every massive event – every black hole or neutron star merger, every supernova – should have sent gravitational waves ringing out across space-time. The combined effect of all these waves would be to create a faint, background hum that permeates the entire Universe.
There are no classes of object in our Universe more extreme than black holes. With so much mass present in such a tiny volume of space, they create a region around them where the curvature of space is so strong that nothing — not even light — can escape from its gravity once a certain boundary is crossed.
Using NASA's Chandra X-ray Observatory, astronomers have seen that the famous giant black hole in Messier 87 is propelling particles at speeds greater than 99% of the speed of light.
By dropping material into the event horizon, we can remove energy and slow its rotation. We can even bring it to a stop. So we can slow down its spin, but that won't make it go away.
Today, we can hear the Sun's movement — all of its waves, loops and eruptions — with our own ears. This sound helps scientists study what can't be observed with the naked eye.
In fact, the only place in the universe with absolutely no sound is where there is absolutely no mass- which can only be found in a perfect vacuum. The absolute minimum sound that can be experienced in any atmosphere as theorized by mathematicians is -23dB, or Brownian motion.
The Loudest Sound, Naturally
The loudest sound in recorded history came from the volcanic eruption on the Indonesian island Krakatoa at 10.02 a.m. on August 27, 1883.
Black holes are obviously terrifying: These crushed remnants of a massive star that exploded as a supernova are so massive that nothing, not even light, can escape its grasp.
Black holes are the most luminous objects in the universe, that they produce no light. Instead, when black holes collide, they twist space-time and cast-off energy greater than the luminosity of all the stars and the universe combined, but in the form of gravitational waves. Inside a black hole, time exists.
As we investigate our Universe, black holes are some of the most violent and mysterious objects we find. Black holes are collapsed objects of incredible density that exert a gravitational pull so strong that not even light can escape.