What happened before the Big Bang?

ULTIMATE QUESTION: What happened before the Big Bang?

Ten years ago cosmologists embraced the theory of the Big Bang. Over the past few years however, physicists, scientists and philosophers have begun to challenge and change their beliefs radically. There are now at least six theories that aim to address the question of what happened before the Big Bang. Some contend that it never even happened in the first place.

What we do know to be true is that the universe is cooling and expanding at an exponential rate. If this process is reversed in time, we end up with all the stuff of the universe condensed into an incredibly hot and incredibly dense ball. However, if we continue to reverse time, we arrive at the idea that everything somehow sprang from nothing — the so-called singularity. This is the biggest issue regarding the Big Bang.

Knowing what happened immediately after the Big Bang 13.7 billion years ago, but nothing of what happened before, has become the most significant question in science and human discovery. What it has done is brought together some of the greatest minds from around the world who offer the following theories in an attempt to address the ultimate question.

Professor Michio Kaku (City College of New York)

Professor Michio Kaku addresses the problem of everything coming from nothing by suggesting that there are different notions of nothing. Nasa has constructed the biggest vacuum chamber in the world, which pumps and freezes out all the atoms over two days. The objective is to create a state of nothing that can be observed.

However, Kaku points out that this state of nothing still has properties. It has dimensions and light can pass through it so that it can be observed. A state devoid of such properties, with no space or time, is termed “absolute nothing”. What has been observed is that in a perfect vacuum energy­ still exists, in which matter temporarily pops in and out of existence. Kaku theorises that the universe may have evolved from this pre-existing state.

Professor Andrei Linde (Stanford University)

Professor Andrei Linde agrees that the universe emerged from a pre-existing state; an energised vacuum devoid of time. However, he firmly believes that the Big Bang is a flawed concept. He contends that it cannot account for the similarity of different parts of the universe.

Linde proposes a theory called “eternal inflation” — an eternal and exponential expansion of the universe. He believes the Big Bang can be cut out of the picture altogether or was, at the least, the end of something else. Theories of inflation appear very elegant in mathematical terms and accounts for the size of the universe and its rapid growth. It also suggests that there are multiple universes. The idea of a multiverse has been widely accepted, yet the theory of eternal inflation has been met with criticism.

Doctor Param Singh (The Perimeter Institute)

Doctor Param Singh believes that notions of the Big Bang are impossible, that it is impossible for everything to come from nothing. Singh believes that that our universe owes its existence to a previous one that collapsed in on itself. Before Singh, there was always a problem of marrying quantum mechanics with Albert Einstein’s general theory of relativity at the mathematical level. They simply clashed.

However, Singh has made progress towards combining the two systems. Recently, he discovered that his new maths predicted a very peculiar phenomenon: that attractive gravitational force becomes repulsive at the level of the very small. Therefore, the point of everything being nothing can never be reached. Rather, everything expands in the opposite direction when the point of the supposed Big Bang is reached. This has been termed “The Big Bounce.”

Singh supports his theory by pointing to cycles found in nature, such as the seasons and the fact that planets orbit around stars. This cyclic nature may be true of the universe too, but it fails to address the ultimate question of what started the infinite bouncing in the first place.

Professor Lee Smolin (The Perimeter Institute)

Professor Lee Smolin takes his inspiration from Charles Darwin and asserts that our universe has an ancestor. He strongly believes that there was something before the Big Bang, but suggests that general relativity is an incomplete theory with more to understand.

Smolin supports the idea of a multiverse­ and suggests that our universe may have been born inside a black hole. When a star runs out of fuel and supernovas, its particles begin to move towards a centre of gravity called a black hole. The star essentially collapses in on itself as more matter gets sucked into an infinitely dense black hole.

Smolin theorises that within a black hole, matter contracts to the point where it explodes and expands, creating a Big Bang type explosion. This natural selection theory of the universe reproducing may either create new regions of our universe, or create an entirely new one on the other side of a black hole. In other words, what we think of as the Big Bang may have been the other side of a black hole in another universe.

Professor Neil Turok (Director of The Perimeter Institute)

In Professor Neil Turok’s paradigm, either time didn’t exist before the beginning and somehow sprang into existence, or, our universe originated from a violent event in a pre-existing universe.

Turok supports the brane theory or M-theory (short for membrane) which is perhaps the most radical of the lot. He believes that we live on one of many extended, three dimensional branes in space. At least two of these branes are required to create matter by colliding with each other. Picture them as two, parallel, flowing curtains in space separated by a gap in the middle. Turok suggests that this gap is the 4th dimension of space in which finite densities of matter and plasma come into existence. In other words, these membranes collide and create other parts of the universe in another dimension.

A final theory suggests that when the universe we know of reaches the end of its life, all that will be left are photons (single particles of light). This mass converts to energy creating an energised vacuum spoken of. At this point in this cyclic system, notions of time and mass disappear, leaving an endless sea of space in which anything is possible.

Or, God made it all.

• This article was inspired by a BBC Horizon documentary called What happened Before the Big Bang? Other BBC Horizon productions include Are We Still Evolving? The Secret World of Pain and What is Reality?