The genesis of the universe. It’s hard to imagine anything happening before the Big Bang, and rightly so. This is because time itself was created at that moment. So what happened before this “moment of creation”? Is it worth pondering this enigmatic and controversial question? We think so.

A Controversial Question?

Because of the nature of the question, it tends to be controversial among physicists. Many claim the question itself makes no sense and refuse to think about it. And in a way, it doesn’t make sense. If time didn’t exist before the Big Bang, how could anything happen before it? Our concept of ‘before and after’ (as we know it) relies on our understanding of time and the concept of ’cause and effect’.

An analogous question would be “What’s north of the North Pole?” The question has no meaningful answer due to our understanding and definition of ‘north’.

This puts the question in a strictly theoretical realm. We’re going to explore several different hypotheses on what happened before the Big Bang, put forth by a few of the world’s leading theoretical physicists.

The Big Bang

Our universe was created in the moment that is known as The Big Bang. Contrary to the imagery and tendency to imagine an actual gigantic explosion, the Big Bang actually refers to the rapid expansion of spacetime itself.

Imagine our universe (and reality as we know it) as a deflated balloon that was compressed to a miniscule point. If you were an ant living on the outside of that deflated balloon, and someone was to blow hard into it, the space (the balloon’s outer surface) would appear to rapidly expand. That first initial hard breath is what is known as the Big Bang. During this short inflationary period, spacetime (and the matter within it) was expanding faster than light. It eventually slowed and cooled. This cooling is what allowed complex matter to form, like stars and planets. The universe is still undergoing a similar expansion, but it is much slower than the initial big bang.

Big Bang Timeline

What Happened Before The Big Bang?

Many physicists and theoretical physicists are unhappy with certain aspects of our current model of the Big Bang. One of the most glaring issues is the absolute beginning – the actual moment itself. As you rewind time to get closer and closer to the beginning of the Big Bang, the math breaks down due to having to invoke infinity (infinitely small in size and infinite in density). By using infinity, we are effectively saying that reality itself has no rules or meaning. Physics and the laws of nature completely break down. In an attempt to make sense of this paradoxical singularity, and restore the reality itself, a few of theoretical physicists have proposed hypotheses on what may have happened before the Big Bang.

The Big Bounce – Prof. Priyam Singh

Using some clever math, Priyam Singh says the universe may go through an infinite cycle of Big Bangs. The universe expands outward, slows, then thanks to an unknown force, it starts to contract. This contraction slowly increases in speed which eventually causes everything in the universe to come together into a single point called a singularity. This singularity then explodes into another Big Bang. This repeated process is what is known as the ‘Big Bounce’. His hypothesis has its own set of problems however, like what caused the first Big Bang to set the cycle motion? It’s still a chicken and the egg scenario. Singh hopes that one day science may be able to answer that question.

Born From A Black Hole – Prof. Lee Smolin

Taking a page from Darwin’s natural selection, Professor Smolin suggests that for a universe to prosper, it must also reproduce. A universe can do this by spawning other universes via its black holes. His hypothesis suggests that as matter gets consumed by a black hole and is compressed into an infinitely small space of infinite density, an opposite bounce (expansion) will take place inside of every black hole at its singularity. This expansion or ‘rebound’ creates a brand new universe and would look very much like our own Big Bang. Only, this new universe would be invisible to anyone outside of the black hole. One problem with his theory is that since we will never be able to observe these new universes being created, his hypothesis will be virtually impossible to prove.

It’s A Brane New World – Prof. Neil Turok

Professor Turok suggests that our universe exists on a 3-dimensional membrane which exists in a higher 4th-dimension. This higher dimension contains other 3-dimensional branes which may also contain other universes. Within his models, a brane can collide with another. Such a collision would cause a massive release of matter and energy – a Big Bang. His theory has the added benefit of being fully calculable using math and does not invoke infinity. It’s an ideal candidate for describing how universe began under String Theory. Such collisions would happen often (every few trillion years), giving new life to dead or dying universes.

Our Universe In A Bubble – Prof Michio Kaku

Another idea similar to the brane universe hypothesis, and is also string theory friendly, are bubble universes. This hypothesis suggests that our universe is floating around in a higher 4th dimension or “hyperspace” inside a 3 dimensional bubble. In this multiverse theory, there are other bubbles which could contain many different universes. New universes are created when a tiny bubble buds off a larger or “parent” bubble. When this budding off happens, a Big Bang occurs inside of the new bubble and it grows as spacetime expands. This process could happen infinitely which means there could be an infinite number of universes inside this 4-dimensional ‘multiverse’.

Testing And Evidence

While wondering what happened before the Big Bang makes for an interesting thought experiment and sparks the imagination, the testability of the hypotheses are nearly impossible in our immediate future. The technology and scientific understanding required for such tests are hundreds, if not thousands of years away.

References:

Wollack, Edward J. (10 December 2010). “Cosmology: The Study of the Universe“. Universe 101: Big Bang Theory. NASA.

Friedman, A. (1999). “On the Curvature of Space“. General Relativity and Gravitation 31 (12): 1991–2000. Bibcode 1999GReGr..31.1991F

Kennedy, B.K. (2007). “What Happened Before the Big Bang?“.

George Ellis (2011). “Does the Multiverse Really Exist?“. Scientific American 305 (2): 38–43.