By Tanushka Bhatnagar
“The important thing is to not stop questioning. Curiosity has its own reason for existing.” —Albert Einstein
What came first? The chicken or the egg? In astrophysics, the same question is modified into, what came first? Galaxies or black holes?
Just like how our Milky Way has Sagittarius A* (a 4 million solar mass black hole) at its center, it has now been proven that supermassive black holes exist in the center of every galaxy out there. But before diving into this, we have to understand the basics.
One of the most fascinating things about outer space, is the nature of quasars. Around 70 years ago, astrophysicists discovered these bizarre objects in the universe. They were extremely bright and far away from our own galaxy. It sounds familiar right? Well, the astrophysicists thought they were distant stars, too, but they realized that each of these objects was emitting much more radiation than a single galaxy!
Eventually they discovered that these quasars were actually black holes. But they weren’t just your average black holes, these had one million times the mass of the sun. One of these monstrous objects existed right in the center of our own Milky Way.
But how did they form? Where did they come from? And why do they exist in the middle of every galaxy? These are just a few of the questions that perplex even the best scientific minds today.
Think of it like this: one could take everything on Earth and the earth itself and stuff it all in a bag the size of a dot. It seems impossible because there’s a limit to how small things can be. The smallest unit in the universe is a Planck length.
You may have heard the famous comparison “if an atom was the size of a football field, the nucleus would be the width of one blade of grass.” Now let’s take the football field and blow it up to the size of the universe. Here the planck length will be the size of an atom. The planck length is small. So how can something be infinitely small, when there is already a limit to the smallest size possible?
According to this concept, singularities shouldn’t exist, black holes shouldn’t exist and Einstein’s general relativity shouldn’t exist as well. So where does that leave us?
Maybe a classical black hole with an event horizon described by general relativity just isn’t the proper description of the physics. In our understanding of physics, there are two places where all our schooling and nobel prizes seem to break down: the heart of a black hole and the small fraction of time before the big bang.
What if these two are linked? A black hole is a dense region where millions and millions of matter come together to such an extent that it cannot be crushed any further. An event like this could in fact lead to a big bang. So what if we are living inside a black hole?
Think about it. When a collapsing matter in any space reaches maximum density it bounces back, expanding outwards at an enormous explosion. This matter gradually cools, forming atoms, stars and eventually planets. If that sounds familiar, its because its just like the universe we see today.
Scientists have found absolutely no way to determine what happened before the big bang, it seems like a blank slate. They can’t quite figure out what goes on inside a black hole, which also seems like a blank slate. The possibility that we are inside a supermassive black hole, which in turn has trillions of supermassive black holes, each of which could be holding baby universes waiting to be born, it’s quite incredible. It’s a never ending loop.
We could literally be the fuel for another universe which would form once Sagittarius A* has devoured our existence. Of course, this is highly theoretical and speculative. Although when you’re stuck in traffic it sure does seem like time is stretching out infinitely, just like it does inside a black hole.