A Complete Guide on What Is The Black Hole

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Introduction

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Have you ever wondered about what goes on in the cosmos? About what lurks in the universe beyond what we can see? There are many wonders that are even yet to be discovered outside of the Earth. 

What we do know about though is the Black Hole. This is an astronomical phenomenon that’s pretty fascinating. Want to learn more? Read on for our complete guide to what black holes are!

What Is A Black Hole?

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So what exactly is a black hole? Well, it is essentially an ‘object’ in space. From this place in space, gravity keeps pulling to the extent that it’s incredibly tricky for any light to get out of it.

Since a lot of matter has been condensed into one location, gravity gets incredibly strong. This can happen for a variety of reasons, but it primarily occurs when a star begins to die. 

Why does it have the name ‘black hole’? In short, it’s because you can’t see it since it’s not possible for the light to get out. 

To summarize, it all comes down to the strength of gravity localized in one area, and as such it’s difficult for any light to get out. Anything that gets into the hole, from matter to radiation, is unable to get out. A little depressing, in a way! 

A black hole is can sometimes be a star that’s dying or dead. Many scientists believe that black holes are usually formed after a huge star dies.

This star will then become a supernova, and the mass that remains will completely collapse because its gravity is so strong. Then, you will have a black hole in return. More on this later! 

There are actually a number of different kinds of black holes out there. 

Different types of black holes:

Supermassive black holes

No, we’re not referring to the song by Muse.

A supermassive black hole is a genuine phenomenon. 

Supermassive black holes are pretty much the largest black holes out there.

Your average black hole has quite a lot of mass, but a supermassive black hole is substantially bigger.

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As of right now, there are only a few supermassive black holes that we’ve confirmed since the vast majority of them exist so far away that they can’t even be witnessed. It is said that there are many more of them in particularly large galaxies.

Most supermassive black holes will exist at around the center of many big galaxies, such as in the Milky Way. 

The only problem with supermassive black holes is that many scientists aren’t entirely sure where they come from. There are a number of theories, however. One of the most prominent arguments comes as a result of studying quasars.

The theory suggests that many of the oldest black holes in the galaxy got to their tremendous size without even becoming supernovas. Supermassive black holes may exist thanks to a chain reaction, according to research by Basu and Das. 

This is just one of many theories out there, however. 

Supermassive black holes are said to be over a million times larger than the sun, and it’s possible for astronomers to find them just from seeing how they affect stars and gas existing near to them. 

Stellar black holes

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One particular type of black hole is the stellar black hole. How are these formed? It all comes down to the stars. 

Towards the end of its life span, a star begins to burn through the very last of the fuel that it has.

When this happens, it can begin to collapse in on itself.

This is a pretty common occurrence with many stars. 

For smaller stars, once they have collapsed the core of the star will go on to be a white dwarf or a neutron star. But what about when a bigger star collapses? That, friends, is when a stellar black hole is formed. 

Larger stars will continue to collapse in on themselves, and eventually it will become a stellar black hole. 

Even though a stellar black hole is formed as a result of a larger star collapsing, it’s still pretty small as far as black holes are concerned. With that being said, these black holes are very dense with a great deal of mass.

With just one stellar black hole there will be more than triple the amount of mass of the sun packed into one small black hole. As such, the gravitational force a stellar black hole can create is pretty significant.

As time goes on, these black holes will keep on eating up any gas and dust from around them, and they will start to gradually get bigger as time goes on.

There are millions of these black holes just in the Milky Way alone! 

Intermediate black holes

So we’ve discussed big black holes and we’ve discussed little black holes. With that in mind, are these the only black hole sizes out there?

Up until recently the answer to this question was believed to be yes, but some recent information has shown that there may be some intermediate sized black holes out there - known as IMBHs, or intermediate black holes.

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It is said that these kinds of black holes may potentially be created when a bunch of stars that have clustered together begin to join together as part of a chain reaction.

If these intermediate black holes all begin to develop in roughly the same area, this could in turn create a supermassive black hole in the middle of a galaxy. 

Some later research from 2018 has suggested that intermediate black holes could possibly form in the middle of dwarf galaxies.

Black Holes Can Only Be Seen Using A Special Telescope 

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Black holes are incredibly difficult to see since they exist so far away.

With that being said, in recent years the black hole has been witnessed for the very first time. 

This is all thanks to something called the Event Horizon Telescope, also known as EHT. This is a ‘network of radio telescopes.’

In essence, a bunch of radio dishes were linked together throughout the earth in order to make something called an interferometer that’s the size of the Earth was created.

The radio telescopes all work together at the same time, and it operates almost like just one telescope alone but with much more power. Thanks to this, images of black holes were seen for the very first time. 

So since we have now seen black holes with the Event Horizon Telescope, you may be wondering what exactly one of these things looks like.

Well, to put it simply, a black hole consists of three different layers. There is an inner and an outer event horizon. There is also a singularity. 

The area that exists around the mouth of the black hole is known as the event horizon. It’s not possible for light to escape beyond this point.

Also, if a particle of an object gets past the event horizon of a black hole, there’s no turning back - that particle is going to be stuck inside of the black hole. 

Then you have the inner area of the black hole in question. This is where the majority of the black hole’s mass exists. This is the singularity of the black hole. 

There are also other ways to detect black holes besides through the Event Horizon Telescope. Usually an astronomer will find a black hole by finding the radiation that it lets out while particles are swallowed by them.

It can be harder to find a supermassive black hole since they can sometimes be covered up by the gas and dust around them, making it much more difficult to find the emissions. 

You can also sometimes see when matter is thrown out of the event horizon of the black hole, since it emits a bright color and it travels at immense speeds.

You would still struggle to see the black hole itself but you can see the bright matter with the right telescope.

How Big Are Black Holes?

Now, you may be wondering exactly how big a black hole is. As we’ve previously mentioned, black holes can come in many different sizes.

The size of a black hole can also be quantified in a number of ways, such as its mass and its volume. 

For instance, a stellar black hole can take up around 10 to 100 solar masses. 

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In comparison, a supermassive black hole could theoretically take up millions or more solar masses. As one example, the supermassive black hole that exists in the Milky Way measures 4.3 million solar masses.

This is pretty large! There are even intermediate mass black holes out there that would likely measure from hundreds to thousands of solar masses.

The smallest black hole that we know of is known as GRO J1655-40. This black hole is said to weigh 5.4 times more mass than the sun - in short, it would have roughly a 10 mile radius. 

What about a stellar black hole? Well, the size of this black hole would rely on the size of the original star. For instance, let’s take the biggest star that we know of - R136a1.

This star weighs around 315 times more mass than the sun. It would have a 578 mile radius if it collapsed and became a black hole. This is nowhere near the size of a supermassive black hole, however.

Many scientists say that the very smallest black hole out there may be just as small as a mere atom.

What is particularly interesting to note is that it’s actually possible for black holes to get even smaller. Now, it’s important to mention again that a black hole will gradually get larger as it eats more material around it.

At the same time though, Stephen Hawking has suggested that they can shrink through time because they will gradually lose small bits of energy. 

The reason for this is because there are particles that exist in empty areas of space.

If a few of these particles materialize near a black hole, at least some of these particles will begin to escape, whereas others will get swallowed by the black hole before the particles are dead. 

The particles that managed to escape find their way back into space. This requires energy from the black hole, and as such the black hole itself begins to lose energy. Then, from losing energy the black hole loses mass. This theory is known as Hawking radiation.

Of course, this isn't something that would happen quickly. It would take millennia for the black hole to shrink that much. 

Could a Black Hole Destroy Earth?

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One of the biggest fears that people tend to have about black holes is that they can destroy earth.

To the average person, a black hole can be seen as something pretty scary that has the capacity to destroy everything around it.

The question is, then, would this even be possible?

This fear could be grounded in some logic, since the gravitational force of a black hole means that many of the things around it get sucked into it. Fortunately though, the chances of a black hole destroying earth are pretty slim.

Likewise, it’s also not possible for a black hole to eat an entire galaxy, even if it’s a supermassive black hole. The truth is, a black hole doesn’t start trying to eat essential parts of the solar system such as the planets and moons. 

Why is this? Well, it mainly comes down to proximity. There aren’t any black holes that exist in close enough proximity to our solar system for Earth to be destroyed by one. What if the black hole was close to Earth?

Well, it still wouldn’t happen. Our Earth isn’t going to suddenly fall into a black hole and existence as we know it is over. 

For instance, let’s say the sun suddenly became a black hole. It wouldn’t be possible for the Earth to fall into the new sun-induced black hole, since the black hole would have the same gravity as the sun does.

In turn, the Earth and any other planets nearby would start to orbit around the black hole just like they do with the sun. 

In theory though, if the orbit of the Earth happened to change too much, we could have some further issues on our hands if the Earth came close enough to a black hole. It’s not something that you really need to worry about, though! 

How Are Black Holes Formed?

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There are many mysteries surrounding black holes and how they are formed, but from our current understanding, it’s believed that a black hole is formed when a huge star begins to collapse in on itself.

This usually happens when a star is towards the end of its lifespan. 

First of all though, it’s worth noting that many astronomers believe there are a few different things that can happen to a star after it has run out of its fuel source. We’ve touched upon it briefly previously in this article, but here’s a more in depth explanation:

  • If a star is relatively small, such as smaller than the sun, it may begin to collapse and eventually it will become a white dwarf. These stars will have a relatively small radius of a couple thousand kilometers.
  • Neutron stars are often created when a star that has more mass than the sun collapses in on itself. The radius of these stars isn’t much more than a couple kilometers. Sometimes these stars can be pulsars.

Now, what about black holes? A black hole is born when a star that has more than four times the mass of the sun collapses within itself. You could basically see it as the dead remnants of a gigantic star. 

The thing is, a black hole doesn’t technically take up any space. What it does consist of though is a whole lot of mass that was once a star.

As we’ve touched on previously, a black hole will also then become larger in mass as it starts to consume the matter surrounding it. If the black hole is particularly large, any particles or matter that gets into the radius of a black hole gets swallowed completely.

Since there is so much mass in the center of a black hole, the force of gravity is massively increased. The black hole creates a tremendously powerful gravitational field, and as such it’s not possible for anything to get out of it. 

A black hole may then become a supermassive black hole if the conditions are right, though again, scientists aren’t certain about how exactly a supermassive black hole is formed. 

Who/How Was The Black Hole Discovered?

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In order for us to know anything about the black hole, someone must have discovered it. In actuality, it is thanks to the work of a number of different scientists that we know all that we do about the black hole.

The discovery of black holes begins with Albert Einstein. In 1905, Einstein began working on his Theory of General Relativity.

This began with something called the theory of special relativity, which establishes the link between space and time in terms of any objects that are traveling at an invariable speed in just a straight line.

Over the next 10 years after this, Einstein worked acceleration of speed into the theory. 

The theory of general relativity, at its simplest level, implies that huge objects in space will bend and distort time and space. This comes as a result of gravity. Gravity is said to exist when time and space are distorted by mass and energy.

For instance, if you were to put a large brick in the middle of a trampoline, then that part of the trampoline would sink.

If you then put a smaller object or ball on the outside edges of the trampoline, then that ball would eventually also fall into that hole - it would be sucked into the pit created on the trampoline as a result of gravity.

Upon reading his Einstein’s Theory of General Relativity, a german physicist named Karl Schwarzchild took this one step further and worked on the idea for black holes thanks to the equations created by Einstein in 1916.

He managed to work out the sort of shape that would be created in space by point mass, which would then foresee an event horizon in that location.

He hypothesized that an astrophysical singularity could potentially distort space time to such a degree that it would not be possible for even light to escape the hole. 

Schwarzschild’s theory is known as something called the Schwarzschild Radius.

It’s essentially what it sounds like - it’s the radius spanning the event horizon around an object that doesn’t rotate. It’s essentially how mass is able to create curves in space in time. 

From there, two more scientists began to get to work on their own theories about black holes. In 1939, Robert Oppenheimer and George Volkoff noticed that burned out stars may lead to massive voids in the middle of space.

They proposed that a neutron star could collapse beneath its weight if it happened to grow too big. As a result, a tremendously forceful gravitational field would be left behind in its wake.

This information would be used by astrophysicists later on to inform understanding on the stellar mass black holes in the universe. 

It wasn’t until later on that it was discovered that the star needed to implode in order for an event horizon to be created, though their theory did pave the way towards that understanding. The understanding at this point was that black holes were pretty rare.

During the 1960s, more information about the black hole came to light. Working together, Stephen Hawking and a scientist named Roger Penrose concluded that actually, black holes and other astrophysical singularities are rather common in space.

They are a natural part of space, and many massive stars eventually become black holes after they have depleted their fuel source completely. In short, a black hole can be seen as part of the natural evolution process of a particularly large star.

What about the name of the black hole? Well, the term was coined by John A. Wheeler in 1967.

Other than what we’ve seen from the Event Horizon Telescope, we also have evidence of a normal black hole thanks to X-Ray Binaries. In 1971, the X-ray binary Cygnus X-1 was found to contain a black hole.

We’ve also found other black holes, such as one in the middle of the Milky Way which is known as Sagittarius A*, or Sgr A* for short. Sagittarius A* was found in 1974 by Bruce Balick and Robert Brown.

This particular black hole exists around 26,000 light years away from us. Our current understanding dictates that this is actually a supermassive black hole.

As we mentioned earlier, in 2019 the Event Horizon Telescope then found the shadow of a black hole in the middle of M87 - this is one of the galaxies near to the Milky Way. 

Research is still going on every day regarding the true nature of the black hole, and we still don’t know everything yet. These are just a few of the things that we’ve discovered through time about the existence of the black hole.

Weird Facts About Black Holes

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Black holes are pretty mysterious, but we do know quite a few interesting things about them. Perhaps you can use these weird facts about black holes as conversation starters on your next blind date! 

Black holes possess a tremendous power. It’s not beyond the realms of possibility to think that a black hole could . The singularity of a black hole alters the laws of physics, so it’s not unreasonable to propose that a black hole could create a new universe.

Technically, Black Holes Don’t Suck Anything In

Black holes are pretty complicated. It’s easy to think, given our understanding, that black holes suck things into their orbit. In reality though, black holes exist much like most other objects that you would find in space.

The main difference is that black holes are known for their incredibly strong field of gravity. If the sun was just a black hole that had the same amount of mass, the Earth and the other planets would just orbit the black hole instead.

The whole Earth isn’t going to be swallowed by the black hole in this circumstance. If surrounding particles do find their way into the black hole then the black hole may take some of those particles in, but they don’t suck in things like planets. 

It is, however, possible for a black hole to spit out some of the particles that it has taken in. These particles are usually made of materials that would slip out of the accretion disk.

Many of these particles that are rejected by the black holes are then essentially vomited out of the hole and right back into the galaxy - they may travel as fast as 20 million miles per hour! You certainly don’t want one of those hitting the Earth, that’s for sure. 

You can’t actually count the amount of black holes that exist

As we’ve previously mentioned, it was initially believed that black holes were scarce. This is most certainly not the case. In fact, in just our galaxy, there are millions of stellar mass black holes.

We also have a supermassive black hole, Sagittarius A* in the center of the milky way. 

In addition to that, the Milky Way isn’t the only galaxy out there. There are said to be 100 billion galaxies existing in space, and each of these has millions of black holes and a supermassive black hole.

For this reason, it’s not actually possible to count all of the black holes that exist in the universe. 

It’s said that supermassive black holes may create new stars

We often think of black holes as objects in space that are capable of mass destruction. This is not necessarily the case. In truth, black holes are also capable of creating new stars.

A supermassive black hole can sometimes release some of its material back into space. This material may then create entirely new stars.

In addition to this, there’s actually information to suggest that supermassive black holes can even determine the amount of stars that are created in a galaxy. It can have an impact on the speed of star formation.

In fact, star formation has been seen to finish much faster in galaxies that have supermassive black holes in the middle of them. Pretty strange! 

It’s not possible to see a black hole directly

Since light can’t actually get out of a black hole, it’s not possible to see one. We can see the gas surrounding the black hole and we can see what’s going on around it, but you won’t see a black hole with the naked eye.

You will often be able to identify a black hole by seeing what kind of effect it has on the areas around it.

Black hole alignment

Some recent studies have found a number of black holes from numerous galaxies aligning in the same direction. This essentially means that they’re emitting gas in such a way that would suggest they’re working in tandem.

It’s pretty bizarre that this has happened, though some researchers think that it happened at some time during early galaxy formation at the start of the universe.

Since these black holes are over 300 million light years away from each other, it’s certainly a bizarre phenomenon.

Spaghetti Time? 

You may be wondering what exactly would happen if you made your way into a black hole. Well, what happens is something that’s known as spaghettification, and it’s exactly as grim as it sounds.

Basically, if something enters a black hole, it stretches the object in question into what looks like a strand of spaghetti. 

When you’re on the earth, your feet are attracted towards the center of the Earth which is where the gravitational pull lies. If you started to become closer to a location that has extreme levels of gravity then the attraction here could cause some massive problems. 

The feet would start to stretch thanks to the pull of gravity, and your feet will become more and more attracted the closer they get to the middle of the black hole. You move faster and faster as you get closer to the middle.

The problem is that your head is still quite far away from the center of the black hole, and this means it isn’t moving quite as quickly. As a result, your entire body would stretch out like a strand of spaghetti. That’s spaghettification in a nutshell!

Now your next question may be whether something like this could kill you. The short answer is yes.

If you did live for a while, you’d likely be in a tremendous amount of pain, since the force of gravity would basically pull your body apart. It would be a pretty excruciating way to die, really. 

This process has even been caught by astronomers in 2019. Of course, it was the star that was spaghettified, not a human! 

Black holes in the movies

Black holes are actually pretty popular things in science fiction, whether it’s for books or movies. Interstellar is one prime example of this. It’s not surprising that they’re such popular subject matter, given the mystery surrounding them! 

Technically, anything could become a black hole

In theory, it’s possible for anything in space to become a black hole. The main characteristic of a black hole is that it has tremendously dense materials in the middle, and this gives it a very strong gravitational field.

If you condensed something like the sun into a size of around 3.7 miles, you could theoretically make it so dense that it could become a black hole. In theory, you could become a black hole.

Realistically though, the only real way that you would have a black hole is if a huge star collapsed into itself. 

In theory, a black hole could create entirely new universes

Black holes possess a tremendous power. It’s not beyond the realms of possibility to think that a black hole could create an entirely new universe.

The singularity of a black hole alters the laws of physics, so it’s not unreasonable to propose that a black hole could create a new universe.

Summary

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Black holes are a pretty mystifying phenomenon. There are so many things that we still don’t know even to this day.

Research is still being conducted about black holes every single day, and who’s to know what we may discover in the years to come? In the meantime, that was our guide on understanding black holes! 

Gordon Watts

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