Can A Black Hole Swallow A Galaxy?

Ever since the existence of black holes was coined in 16967 by astronomer John Wheeler, understanding and theory around them has grown.

At first black holes – or more specifically singularities within space-time – were thought to be theoretical objects that were highly debated, and eventually confirmed through a collection of evidence. 

Most people know black holes to be large black voids in space that suck up anything near them. Although this is a simplified explanation as to what they are, it’s the best-known definition and poses a lot of questions. For example, what happens when a black hole comes into contact with other interstellar objects? Can a black hole swallow an entire galaxy?

To answer this question, we’ve created a short article to explain what a black hole is, how they work, and whether or not they could swallow something as massive as an entire galaxy. We’ve also included a short FAQ section to explain some of the more common misconceptions about black holes.

What Is A Black Hole?

Before we can answer any questions regarding whether or not a black hole would swallow a galaxy, it’s best to first understand what they are. 

In short, a ‘black hole’ is a name scientists have created to explain regions of spacetime where gravity is so strong that nothing can escape it. They are called black holes because nothing – not even light – can escape this gravitational pull and therefore they appear to be black voids. 

Black holes were first predicted by the theory of general relativity, which predicts that areas of extremely compact density can bend spacetime to create an area where gravity is intensely strong. Black holes most commonly form from large stars that reach the end of their lifecycles in supernova explosions. A black hole is just one of many different ways that the life of a star can end. 

Beyond this, there is much debate as to the actual physical mechanics of a black hole – specifically what goes on within its ‘event horizon’ (the place where light cannot escape). This is because we can’t see what happens there, and there are only theories. One, for example, is that the singularity of a black hole (center) is infinitely dense – this is a theory used to explain how it could have such intense gravity. 

In April 2019, an image of a black hole was captured for the first time. It’s not exactly an image of what is inside the black hole, nor the black hole itself because there is no way to capture something so dark – instead, it is an image of the heat around the black hole and the dark void of its center. This is some of the strongest modern evidence we have for the existence of black holes. 

Can A Black Hole Swallow A Galaxy?

To answer this question, it’s first important to note that it is common for a black hole to be at the center of a galaxy. For example, in the center of our galaxy (the Milky Way), there is a supermassive black hole known as Sagittarius A that is thought to be over 4 million times larger than our sun. Even though Sagittarius A is big enough to affect every part of our galaxy, it’s not so big as to swallow it. 

Black holes can and have swallowed stars, but we haven’t yet seen evidence of a black hole that is big enough to swallow an entire galaxy. A galaxy such as the milky way is 52,850 light-years in radius, which is much, much bigger than Sagittarius A, so it would be unable to swallow such a great amount of mass. This is good news for us, as citizens of the Milky Way and we can rest easy at night.

That said, if our planet was to come into close contact with Sagittarius A, we would be unable to resist its gravitational pull and all life would be wiped out very quickly. 

Misconceptions About Black Holes

There are many misconceptions about black holes, one of which is that they are endless vacuum cleaners that suck in everything they can around them. In reality, the matter can orbit black holes in the same way as anything else. Many stable galaxies have a supermassive black hole within them. 

A good way to illustrate this is to show imagine our own star was replaced with a black hole of the same size. If this happened, our earth and all of the planets in our solar system would likely continue to orbit it. However, it’s important to note that this hypothetical event would destroy all life on earth as the black holes produce no heat or light so the earth would likely freeze.

So then why is there such an image of a black hole as something that sucks everything around it in? It’s mostly because anything that passes through the ‘event horizon’ of a black hole has 0 chance of ever escaping. In order to escape a black hole, you would have to achieve a velocity greater than the speed of light, which – according to current our current understanding of physics – is impossible. 

Final Thoughts

We hope that this article has given you some insight into whether or not a black hole could swallow a galaxy. From what we know, black holes are not currently big enough to swallow a galaxy, but that’s not to say that our scientific understanding can’t change in the future. If there ever is a black hole large enough to swallow a universe, it’s certainly not something we’d want our solar system to be close to! 


What Happens If A Person Is Swallowed By A Black Hole?

In short – we don’t know. That said, there are several good guesses that scientists have come up with to answer this question. It’s very likely, no matter the type or size of a black hole you fall into, that your body would be ripped apart by extreme gravity. Once a human passes the event horizon, you would likely be destroyed and it would be impossible to get back alive. 

What Is Inside A Black Hole?

The most common theory for what is inside of a black hole is called a ‘gravitational singularity.’ A gravitational singularity would be a place in the universe that is so dense that space-time would extend into infinity. This is a mind-boggling concept that has puzzled scientists ever since it was proposed, and to many, it appears that an object with infinite density should not exist. 

What Is The Largest Black Hole In The Universe?

The largest black hole in the universe – known as an ultramassive black hole – is thought to be 66 billion times the mass of our sun. This kind of number is impossible to imagine for humans, let alone the size of that within the wider universe. 

Do Black Holes Really Exist?

The concept of black holes was born out of theory, though through observation we have been able to confirm their existence. Like many things in science, the existence of black holes is always subject to scrutiny and change, but so far it appears that they exist. Most of the evidence we have about black holes comes from their effect on space around them. 

For example, you can’t see a black hole because it doesn’t radiate or reflect light – but what it does do is have extreme gravitational effects on nearby bodies. This can be detected, tracked, and documented by scientists. 

Gordon Watts