One of the biggest questions that humanity has ever asked is how the universe came to be, and after centuries of research in the matter, we now have a standard model of Physics which explains how the universe could have started.
We all know the genesis event as The Big Bang which brought everything into existence from a single point of unimaginable density, consisting of heat and energy. In an instant, the universe literally inflated into existence and this process is even going on right now.
The universe has been expanding ever since the beginning and observations made in the last several decades shows that the expansion rate of our universe is accelerating, leading everything to become more distant from everything else.
Even though we know all of this, one question remains and this has been the bane of modern Physics. What was there before the Big Bang? How can something be created out of nothing? While we do not have a clear answer as of now, there are some theories as to what existed before the big bang.
An Endless Cycle of Expansion and Contraction
We know for certain that our universe is expanding which is thought to be caused by 'dark energy' about which we really don't know anything. While gravity pulls things together, it seems like dark energy is driving them apart.
Some scientists hypothesise that this process of expansion could reverse at some point in the future leading everything to contract over a period of billions of years. If that happens, then at some point, everything will be contracted to an infinitesimal point. This was the exact condition at the time of the big bang.
From there on, another cycle of expansion and contraction could begin. This would mean that the universe is and was always in an endless cycle. Although it gives us a greater perspective, it still doesn't answer what was there before this cycle.
Born Out of A White Hole?
You might know about black holes as they're increasingly becoming popular in pop culture. A very accurate model of one was shown in the movie Interstellar. Just a few decades ago, scientists weren't even sure that a black hole exists and now just recently they managed to take an image of one.
A black hole is basically a cosmic object that has an insanely powerful gravitational field. So powerful that electro-magnetic radiation itself cannot escape its pull. That means not even light can escape its pull once it crosses a region called the event horizon. Currently we have no idea what happens inside a black hole or at its centre.
A white hole on the other hand is a hypothetical object that is just the opposite of a black hole and instead of sucking in matter and energy, it gives them off. So, some scientists think that maybe our universe was born out of a white hole which served was spewing out matter and energy that its black hole counterpart had sucked in from a different universe.
From A Sea of Universes?
There's a theory that states that there our universe is just one of an infinite number of universes that exist in a higher dimensional plane. Each universe could be compared to a bubble among a sea of bubbles that are just floating about.
These other universes could have completely different laws of Physics altogether and they might be popping in and out of existence all the time. Although how exactly our universe just 'popped' into existence would still not be answered, if this theory is proved true, we would definitely have some even bigger questions to ask. How did the multiverse itself start?
Maybe everything did come from nothing. Or maybe its like a circle and there is no end or beginning like we understand it. Or maybe there was some divine power that created it all. I hope we do get concrete answers in the future.