We believe that everything in the universe was created at roughly the same time and because of the same reason. An infinitely small particle with an infinite mass exploded several billion years back, expelling mass throughout space, creating everything from the universe to the galaxies, solar systems, stars, planets, moons and asteroids as they are now. This concept is called the Big Bang Theory, widely accepted by science and pop-culture as the origin of the universe. And while it is relatively more simple to predict the sequence of events after the big bang, there is yet one question left not just unanswered, but one with no means of answering given current technology and knowledge. What was there before it?
There are multiple theories regarding events leading up to the big bang. A common one suggests that there was nothing but helium and hydrogen particles in the universe before the big bang. According to this theory, these gasses compressed over time into the small particle with infinite energy discussed before, the explosion of which eventually caused the big bang
A second theory proposed by Sean Caroll suggests that before the big bang, the universe consisted of a very dense matter present throughout. This high energy matter, held together by some force, loses its stability for a yet unexplored reason causing the explosion. Another one suggests that the universe follows a cycle of big bangs- compressions followed by explosions followed by compressions again, destroying the old structures and creating something new with each explosion. This cycle began an infinite amount of time ago and will continue forever.
These theories contrast each other, and though they all provide interesting perspectives to the question asked, they still are theories, and can not say with certainty that the big bang happened, or will happen again.
In the words of theoretical physicist Dr. Shiraz Minwalla, “If you make a movie of the universe and run it backwards, you come to a point just before the big bang in which this film becomes grainy, because the equations of physics you need to run the movie further back are as yet, unknown.”
All the same, such ideas beg the question - Is the universe really infinite?
Almost a hundred years ago, an astronomer named Edwin Hubble realized that the galaxies around ours were moving away from us. By extending this idea, it was safe to assume that the universe was at one point in time the size of a peach, with its mass unchanged (since matter can not be created, nor destroyed). This could either be caused by expansion of the universe at the edges, or an unknown force towards the center beyond the reach of our measurements that's pulling the galaxies towards itself. And again, we don’t know for sure.
Stephen Hawking speculated that the universe is finite but it has no boundaries. It is in some way, like Earth, as the Earth is finite but it doesn’t have any boundaries due to being in a spherical shape. This theory also suggested that the universe didn’t necessarily have a starting point. This theory doesn’t say if the universe is expanding, but it doesn’t rule out the possibility of the same.
I believe Sean Caroll’s theory about how matter was present in the universe more because there has to be something that is causing such a huge explosion. I also think that Stephen Hawking’s theory about the universe being finite with no boundaries is true because of our current vision of the universe, and because we may have been able to expand it if there was something beyond it. But we might never find out the answers to these questions. If we do, then we will just find more questions without any certain answers.
The study of astronomy gives a horizon to so many new ideas and questions, finding the answer to which will allow us to understand the universe much better. It is a thought we’ve all had when we look up at the nightsky, a question that we want answered. Until that answer is known, developing new theories will allow us to look further into this topic and explore its multiple dimensions.