In my view, one of the more interesting arguments – recently debated by evolutionary biologist and famous atheist Richard Dawkins and the archbishop of Sydney, Cardinal George Pell – was around how the universe was created.
This involved questions addressing what caused the Big Bang and whether that necessitated creating something from nothing, thus providing evidence for the existence of God.
As a science undergraduate, I came across two common answers to the question of what came before the Big Bang. The first was something like “as both space and time were created in the Big Bang, there was no time before the Big Bang; thus it doesn’t make sense to ask what came before it”.
The second was that, in simple terms, the whole universe is the result of a quantum fluctuation in some pre-universe vacuum. This latter view is clearly articulated by the Canadian-American theoretical physicist Lawrence Krauss, who has written a book on the subject.
I have since discovered there are a plethora of mind-stretching (and highly speculative) hypotheses around the birth of our universe. They all involve the idea of a vast multiverse, comprising a potentially infinite number of universes that are interrelated in various ways. So let’s jump right in and discuss some of these ideas.
Eternal chaotic inflation
Eternal chaotic inflation is a variant of the inflation model of the universe, which describes how the early universe was thought to have expanded extremely rapidly.
To visualise this hypothesis, imagine a chaotically fluctuating field. The peaks of that field then become points from which exponentially expanding patches of space grow to become “bubble universes”.
This multiverse has Big Bangs going off constantly in exponentially increasing numbers for all eternity. In this view, one of these Big Bangs resulted in the universe we currently observe, but our universe is just one within a huge multiverse.
Apart from a different beginning, it’s very similar to the standard Big Bang theory in describing the evolution of structure in our universe.
String theory involves extra-spatial dimensions, which we can’t detect because they are “compactified” or curled up on very small scales.
It predicts particles as different types of vibrations on “strings” in these extra dimensions. There is a generalisation of string theory called M-theory, which involves 11 dimensions and fundamental objects called “branes” (short for membranes).
M-theory predicts that branes exist in varying forms across all 11 dimensions. Our universe is seen as existing on or within a three-dimensional brane embedded in a higher-dimensional space.
To really get to grips with this hypothesis, we need to imagine two massive three-dimensional branes. We could think of them as some sort of proto-universes, embedded within a higher-dimensional space.
The Ekpyrotic Universe hypothesis then speculates that our universe was formed when two such branes collided. The two branes “stuck” together and released massive amounts of energy from the collision that was confined to stay with the three-dimensional branes.
This sudden burst of energy produced radiation and subsequently all the particles that make up our universe, in the same way as occurs within the standard Big Bang theory.
This hypothesis, proposed by theoretical physicist Lee Smolin, magnifies the process of evolution to some of largest scales conceivable.
If correct, it would mean our universe was born from the heart of a black hole contained in another universe.
It would also imply that all the black holes in our universe are giving birth to new baby universes. The idea here is that the singularity at the heart of a black hole gives birth to a new space-time, resulting in a whole new universe separate to our own.
The fecund universes hypothesis (also known as cosmological natural selection further supposes that in each new universe the laws of physics will be slightly different from the mother universe that gave birth to it.
The fact that black holes would provide a mechanism for giving birth to new universes results in a natural selection pressure for universes with laws of physics that allow black hole formation.
This process of replication, mutation and selection pressure means that the multiverse is likely to be dominated by universes that allow black hole formation.
Our universe certainly falls into this category.
The selfish biocosm (SB)
The SB hypothesis was developed by theorist and author James N. Gardner who, unlike the creators of the previously mentioned hypotheses, is not a physicist – though his hypothesis has been published in peer-reviewed journals.
Gardner’s main idea is that life itself facilitates the feat of cosmic replication resulting in the birth of new baby universes.
This would occur after life had been evolving for billions of years, resulting in highly sophisticated intelligences that would infuse the entire universe.
These highly evolved intelligences would develop a level of understanding of the laws of physics that would allow them to create new baby universes.
Gardner further proposes these intelligences would choose to design new baby universes with laws of physics that would allow new intelligent forms of life to evolve.
This idea has some interesting implications. For one, it predicts the ability of the laws of physics in our universe to support life is not an accident, but results from an evolutionary chain of universes within a multiverse, with each generation becoming increasingly “bio-friendly”.
Gardner’s description of highly evolved intelligences – infused throughout their universe, with the ability to create new universes, potentially at will – could also fit very will with some definitions of God.
The SB hypothesis thus implies the future destiny of intelligence in our universe may be to become this type of “God”. Further, it implies this emerges from the laws of physics that have been “designed” by the “Gods” in our mother universe.
Importantly, this obviously speculative hypothesis attempts to be consistent with current scientific knowledge and requires no intervention from an external God.
Compared with these mind-stretching ideas about the origin of our universe and the potential structure of the multiverse, the debate between atheists and creationists about how, or if, the universe could be created out of nothing can perhaps be seen as simplistic.
The debate would become considerably more interesting if those on both sides more thoroughly familiarised themselves with these and other similar ideas.
While the possibility of any of these hypotheses being correct doesn’t provide new evidence for or against the existence of God, they do point to an ultimate reality that’s potentially far more interesting than we originally thought.