NASA recently released the sonification of a supermassive black hole that exists in the center of Perseus galaxy. A galaxy that is around 24 Million lightyears from Earth.
Black Holes have been around for some time and they are probably the first cosmic body that everyone is equally curious about and I don't blame them. The all-consuming black hole is something straight out of sci-fi. However, even though awareness of black holes is so ubiquitous, we as humanity don't know much about them. They are still very much a mystery.
Black Holes Origin Story
In 1916, while presenting his work on the theory of general relativity, Albert Einstein alluded to the fact that we must have some massive objects in our galaxy that distort the fabric of space and time and essentially manifest as gravity...very high gravity. That we must have this place where singularity exists and where everything becomes one. According to him, this is a kind of highly tense object that consumes everything that's around it.
Then in 1964, NASA discovered its very first black hole (almost). NASA, essentially, recorded very high x-ray radiations coming from a celestial object. Three years later, in 1967, John Wheeler coined the name "Black Hole" for whatever the source of these radiations may be. But it wasn't until six years later, in 1971, that NASA determined that this radiation was coming from a pale blue star that was orbiting this very strange dark object. That dark object was indeed a black hole, and hence marked the beginning of the discovery of black holes.
Why Are Black Holes So Mysterious?
Now, what makes black holes so fascinating and at the same time so mysterious is the fact that space is predominantly black, and black holes...you guessed it...are black. So essentially, black holes are invisible. So if by any miracle you happen to be walking in space, you would never know that there is a black hole around you unless you reach the event horizon. Event Horizon is the "point of no return" and once you do reach it, you would inevitably get sucked into the black hole. So basically, you stand no chance against a black hole.
How Are Black Holes Formed?
Now we know that stars are constantly forming and dying. And when stars die, they either form a neutron star which is like a dead body of a cold star; a dwarf star that just floats in space unless it collides with another neutron i.e., neutron star collision which can form a black hole. But if a star with a mass of more than 3x that of the sun dies, then it doesn't form a neutron star. Instead, it forms a black hole.
Now, black holes can either be as small as the size of an atom which is called "primordial" black holes. Or they could be stellar black holes that are slightly bigger. Or they can be supermassive black holes that are huge. Sometimes these are even the size of galaxies. The mass of a black hole is largely dependent on the size of the dead star that forms the black hole or the amount of matter it consumes.
Hence, even a black hole that started out as the size of an atom, could potentially become a stellar black hole and a supermassive black hole in the longer run.
It is also discovered that almost all the largest galaxies in our universe have a supermassive black hole right in the center of them, including the Milky Way. The supermassive black hole at the center of our galaxy is called Sagittarius A*. The origin of which is somewhat of a mystery in itself.
What Are The Black Holes Made Of?
Black Holes have three parts: the upper and inner event horizon and the singularity. I mentioned the event horizon above, it is really just the point of no return, i.e., a forcefield around black holes that either sucks things in or push them far away. However, if you were to enter it, you wouldn't be able to exit it. It is the perfect trap. It is also a kind of filter too because if the mass of an object isn't big enough, it would be pushed in the opposite direction of the black hole rather than get sucked inside.
Singularity is much more complex and our knowledge of it is mostly theoretically based. Singularity is basically a point in space where everything becomes one. Everything in the black hole disintegrates into atoms and particles and you wouldn't be able to sort of distinguish one thing from another.
What Would Happen If Humans Fall into it?
The answer to this is very anti-climatic i.e., Humans can practically never fall into it. As mentioned above, Event Horizon is also a kind of black hole filter, it only lets objects with considerable mass to get sucked in. Unfortunately, Humans are practically ants in the grand scheme of things and don't have high enough mass to be sucked into the mighty black hole. In fact, the event horizon would push us far away into the space, opposite from the direction of black holes.
But if by some force humans do end up crossing the event horizon, scientists say that humans will be experiencing the process called "spaghettification" where the event horizon simultaneously pulls us away as the inner curvature of black hole pulls us in. So that doesn't sound like a lot of fun.
White Hole: Myth Or A Reality?
I think something that any curious mind would want to know is that things get inside a black hole, but do they ever come out of it? And the answer to that is that we shall never know because everything that we know of inside a black hole is theoretical. Our knowledge of black holes is limited to the event horizon. But there are suggestions that at the other end of the black hole is a white hole that operates in the complete opposite fashion of that of a black hole.
A white hole would be a place where everything only gets pushed outside and nothing can enter. So suppose there is a spaceship that entered a black hole, on entry, it disintegrates into atomic particles but then when it reaches the white hole, it comes out of it in the same physical form that it was before it entered the black hole. Kind of a real manifestation of a rewind button. We don't have any evidence that this phenomenon does exist, but this is what Einstein's theory of relativity sort of prefaced at a bit.
The First Time We Ever Saw A Black Hole
It wasn't until 2019, that we were first able to visualize black holes for the first time ever. This discovery was a breakthrough in the study of black holes because it proved so many of our theories. First of all, certain properties of Einstein's theory of relativity were proven to be correct. His idea of a black hole completely coincided with what black holes were like for real and in a weird twist of events, the interstellar movie's rendition of a black hole was also proven to be remarkably accurate.
First ever image captured of M87, a supermassive black hole in the center of Messier 87 GalaxyIn the picture, you can see a round gaseous structure i.e., the glowing gas moving at the speed of light and in the middle of it, you see a "shadow" which is the black hole. The Black Hole is called M87 and has a home in the middle of Messier 87 galaxy. By the way, this particular picture took two years' worth of study so it was a MASSIVE feat and a milestone in space discovery.
Highly detailed image of Sagittarius A*, a supermassive black hole from the Milky Way, showing the rings made by the movement of the gasses that spin around the black hole at the speed of light.
NASA was able to visualize a second black hole in 2022. This one was near to our home...yes you guessed it.. it was none other than the Sagittarius A*. This black hole was also more massive than the M87 one. Plus we were able to get a more detailed picture out of this one. In this image, you could also make out the rings of the gaseous structure that spun around the black hole at a remarkable speed.
What's Next?
Hold on, the discovery of black holes does not end here. NASA is confident that in the years to come, our knowledge of black holes would be expanded exponentially. These images of two different black holes are just a start that will help us supplement our insights into these mythical objects But right now our discovery of black holes is in an introductory stage.
BTW if you are curious about space like I am, you have to check out the podcast below. You can also find an episode on black holes which *psst* I would totally recommend. (The Podcast is available on Apple Podcast, Google Podcast, Spotify or wherever you listen to podcast - Click here!)
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