What happened before the Bang?
Cosmologists do not yet know how the universe began right at that first moment, but this question has now come within the realm of science with a number of speculative scenarios being discussed:
All these scenarios meet at the bang, but what we really know for sure commences at the Planck time, 10-43 seconds thereafter, when space and time start to take shape[2]. However, of recent times, a coterie of theoretical physicists have been able to come up with some sort of an answer as to what may have happened. It depends to a large extent on two principles whose full parameters will be explored in more detail later: a multiverse with more than three dimensions and the holographic principle.
Under this scenario[3], our three-dimensional universe is merely the shadow of a world with four spatial dimensions, and the universe we know came into being during a stellar implosion in this supra-universe, an implosion that created a three-dimensional event horizon shell around a four-dimensional black hole. Our universe is that black hole. The quest for an explanation culminating in a holographic explanation of our universe’s emergence from this four-dimensional universe has come about because of problems inherent in the interpretation of our three-dimensional one, such as the flatness problem, inflation, and the lack of a satisfactory description of the history of our cosmos before the inflationary era – those first trillionth of trillionths of a second after the big bang. And this is not just idle speculation, but firmly grounded in the mathematics that describe space and time. Over the past several decades, physicists have been able to develop a rich theory of holography: a set of mathematical tools that allow them to translate descriptions of events in one dimension to the physics in a different dimension.
Problems with the Standard Model
These have already been explored. First, the period of rapid expansion following the bang provides no insight into what caused the bang itself. Second, we also lack a satisfactory description of the history of the cosmos before the inflationary era – those first trillionths of trillionths of trillionths of a second after the bang. Third, nor do we have an explanation as to how that so-called “bang” – the abrupt origin of space and time in a hot plasma of radiation and particles at a temperature above 1027 degrees – could lead to what we observe today: a cosmos of nearly uniform temperature with a flat large-scale spatial curvature (one in which the angles of triangles add up to 180 degrees).
But perhaps the biggest question of all is understanding the bang itself – the sudden and violent emergence of all space, time and matter from an infinitely dense point called a singularity. Singularities also form at the centres of black holes, the collapsed remains of giant stars. The boundary of a black hole – a two-dimensional surface called the event horizon – is a point of no return. Everything that falls within this boundary is cut off from the rest of the universe and inexorably pulled towards the singularity at the centre.
As with the bang, the laws of physics break down at this singularity as well, but unlike the bang, a black hole is surrounded by an event horizon, preventing any information about the singularity from leaking out. “Cloaked by an event horizon, the singularity is rendered impotent. Its disturbing effects cannot escape, making it possible for the laws of physics to describe and predict all we observe”.
Our universe is a hologram for a four-dimensional star collapsing into a black hole
So what has all this to do with the creation of the universe? In essence, the authors postulate that our universe began when a star in a four-dimensional universe collapsed to form a black hole, one whose singularity is cloaked with an “event horizon” with three spatial dimensions, not just two, thereby protecting us from the singularity’s “mercurial and nefarious” effects. Modelling suggests that on this scenario, the material ejected from the stellar collapse of this four-dimensional star can form a slowly expanding three-brane – a hologram of sorts for a four-dimensional star collapsing into a black hole. The cosmic big bang singularity then becomes hidden to us - locked forever behind a three-dimensional event horizon.
The fundamental idea of a brane world[4] is that our three-dimensional universe (a brane) is a sub-universe embedded in a larger world of four or more spatial dimensions (the bulk). All known forms of matter and energy are stuck to our three-dimensional brane like a movie projected on a screen, the exception being gravity, which permeates all of the higher dimensional bulk. This bulk supra-universe of four spatial dimensions that may have existed before the bang was possibly filled with objects such as four-dimensional stars and four dimensional galaxies, some of which might have run out of fuel and collapse into four-dimensional black holes each with an event horizon, a surface of no return from which no light could escape, and each with three spatial dimensions, not the two we are familiar with.
This scenario provides answers for the problems inherent in the Standard Model
It explains a lot of things:
“In this way, our model of a holographic big bang resolves not only the main puzzles of uniformity and near flatness of standard cosmology without resorting to inflation but also nullifies the damaging effects of the initial singularity”.
- First, there was no previous era. Matter, energy, space and time began abruptly with the big bang.
- Or maybe ordinary space and time developed out of a primeval state described by a quantum theory of gravity.
- Or perhaps there is a multiverse with our universe and others budding off from eternal space[1].
- Then again maybe the answer lies in a cyclic universe. Under this scenario, the big bang is but the latest stage in an eternal cycle of expansion, collapse and renewed expansion.
All these scenarios meet at the bang, but what we really know for sure commences at the Planck time, 10-43 seconds thereafter, when space and time start to take shape[2]. However, of recent times, a coterie of theoretical physicists have been able to come up with some sort of an answer as to what may have happened. It depends to a large extent on two principles whose full parameters will be explored in more detail later: a multiverse with more than three dimensions and the holographic principle.
Under this scenario[3], our three-dimensional universe is merely the shadow of a world with four spatial dimensions, and the universe we know came into being during a stellar implosion in this supra-universe, an implosion that created a three-dimensional event horizon shell around a four-dimensional black hole. Our universe is that black hole. The quest for an explanation culminating in a holographic explanation of our universe’s emergence from this four-dimensional universe has come about because of problems inherent in the interpretation of our three-dimensional one, such as the flatness problem, inflation, and the lack of a satisfactory description of the history of our cosmos before the inflationary era – those first trillionth of trillionths of a second after the big bang. And this is not just idle speculation, but firmly grounded in the mathematics that describe space and time. Over the past several decades, physicists have been able to develop a rich theory of holography: a set of mathematical tools that allow them to translate descriptions of events in one dimension to the physics in a different dimension.
Problems with the Standard Model
These have already been explored. First, the period of rapid expansion following the bang provides no insight into what caused the bang itself. Second, we also lack a satisfactory description of the history of the cosmos before the inflationary era – those first trillionths of trillionths of trillionths of a second after the bang. Third, nor do we have an explanation as to how that so-called “bang” – the abrupt origin of space and time in a hot plasma of radiation and particles at a temperature above 1027 degrees – could lead to what we observe today: a cosmos of nearly uniform temperature with a flat large-scale spatial curvature (one in which the angles of triangles add up to 180 degrees).
But perhaps the biggest question of all is understanding the bang itself – the sudden and violent emergence of all space, time and matter from an infinitely dense point called a singularity. Singularities also form at the centres of black holes, the collapsed remains of giant stars. The boundary of a black hole – a two-dimensional surface called the event horizon – is a point of no return. Everything that falls within this boundary is cut off from the rest of the universe and inexorably pulled towards the singularity at the centre.
As with the bang, the laws of physics break down at this singularity as well, but unlike the bang, a black hole is surrounded by an event horizon, preventing any information about the singularity from leaking out. “Cloaked by an event horizon, the singularity is rendered impotent. Its disturbing effects cannot escape, making it possible for the laws of physics to describe and predict all we observe”.
Our universe is a hologram for a four-dimensional star collapsing into a black hole
So what has all this to do with the creation of the universe? In essence, the authors postulate that our universe began when a star in a four-dimensional universe collapsed to form a black hole, one whose singularity is cloaked with an “event horizon” with three spatial dimensions, not just two, thereby protecting us from the singularity’s “mercurial and nefarious” effects. Modelling suggests that on this scenario, the material ejected from the stellar collapse of this four-dimensional star can form a slowly expanding three-brane – a hologram of sorts for a four-dimensional star collapsing into a black hole. The cosmic big bang singularity then becomes hidden to us - locked forever behind a three-dimensional event horizon.
The fundamental idea of a brane world[4] is that our three-dimensional universe (a brane) is a sub-universe embedded in a larger world of four or more spatial dimensions (the bulk). All known forms of matter and energy are stuck to our three-dimensional brane like a movie projected on a screen, the exception being gravity, which permeates all of the higher dimensional bulk. This bulk supra-universe of four spatial dimensions that may have existed before the bang was possibly filled with objects such as four-dimensional stars and four dimensional galaxies, some of which might have run out of fuel and collapse into four-dimensional black holes each with an event horizon, a surface of no return from which no light could escape, and each with three spatial dimensions, not the two we are familiar with.
This scenario provides answers for the problems inherent in the Standard Model
It explains a lot of things:
- It eliminates the naked singularity that gives rise to the universe in the Standard Model.
- Because the four-dimensional bulk universe would have existed for a long time in the past, the bulk universe would have had ample time for any hot and cold spots to come to equilibrium.
- The bulk universe would be smooth and our three-brane universe would inherit this smoothness.
- In addition, because the four-dimensional black hole would appear to be featureless or, as they say, “without hair”, our emergent three-brane universe would likewise be smooth.
- And the larger the mass of the four-dimensional star, the flatter the three-brane, and so the flatness of our universe is a consequence of it being residual detritus from the collapse of a heavy star.
“In this way, our model of a holographic big bang resolves not only the main puzzles of uniformity and near flatness of standard cosmology without resorting to inflation but also nullifies the damaging effects of the initial singularity”.
Source: "Before the Big Bang": “The black hole at the beginning of time”, Article by Niayesh Afshordi, Robert B Mann and Razich Pourhasan, Scientific American, August 2014, 30-31.
The explanation in small print above reads: In the standard story, the big bang began with a singularity, an infinitely dense point that gave rise to the entire universe. Singularities are unpredictable, however: the laws of physics break down there and there is no reason to think that one would create the world we see. Instead, the authors postulate that the universe began when a star in a four-dimensional universe collapsed to form a black hole. Our universe would be protected from the singularity at the heart of this black hole by a three-dimensional event horizon. Here we depict the process in 3-D because no one knows what a 4-D cosmos would look like.
At mid-graphic, the 4-D universe is shown in 3-D form, and then the event horizon separating it from the 3-D universe which which we are familiar. The conventional story is then depicted with a singularity, illustrated by a white dot followed by inflation (the black curve), the CMBR, the dark ages and first stars.
One way of testing this hypothesis is by measuring distortions in the CMBR which may have been pulled by the gravitational effect of the four-dimensional black hole. The research here is presently inconclusive and a work in progress. But, assuming for the moment the correctness of the group’s proposed solution, the problems inherent in the big bang are now subsumed by another: where did our universe’s parent universe come from? We don’t yet understand the four-dimensional universe or what it and its features look like, but thanks to our learned authors, at least we now have a hypothesis to explore for answers.
But wait, there's more!
All these issues – the problems with the big bang itself, the horizon problem and the flatness problem are analysed in the Brian Cox documentary Life of a Universe: Part 1 – Creation https://www.youtube.com/watch?v=Or2Itbzxo6A at about 11.30 minutes in, leading to the conclusion that perhaps infinite space is filled with what is known as a scalar field, something like an ocean with built-in repulsive energy causing it to expand, bringing about new universes within, a multiverse in other words, something like holes in a swiss cheese, according to Brian Greene’s colourful analogy. Considered in this way, the big bang was merely an event in a pre-existing universe - not a single event, but part of a continuing process.
The energy within this field is never fully used up and continues to expand inexorably, leading all the while to big bang after big bang after big bang as new bubble universes are brought into being. Within these bubble universes, some ripples in the scalar field ocean are of greater density and intensity than others and collapse into each other, in the process forming stars, galaxies, asteroids and so on.
All this is not idle speculation says Greene. It is firmly grounded in the mathematics of inflationary cosmology. And as these new universes are being created, every possible possibility that can happen does happen and universes are being created many times over and continue being created. Considered in this way, our existence is inevitable, concludes Brian Cox, and inflation is the key. So this is also essentially the story as to how our own universe got going, well at least according to the theory!
But it's also the story about how it ends. As inflation stops, our own universe also grinds to a halt, but others are being constantly created in the process [5].
[1] Explored in Brian Greene, The Hidden Reality – Parallel Universes and the Deep Laws of the Cosmos, Alfred A Knopf, New York, 2011Probing the Mysteries of the Cosmos, August 2013, 37 at 38.
[2] Michael S Turner, “Origin of the Universe”, Scientific American: Special Collector’s Edition: Extreme Physics, Probing the Mysteries of the Cosmos, August 2013, 37 at 38.
[3] For the following material, see Niayesh Afshordi, Robert B Mann and Razich Pourhasanmay, “The black hole at the beginning of time”, Scientific American, August 2014, 27-33. This material represents a synopsis of the main thrust of the article.
[4] Branes are explored in the segment on string theory.
[5] Brian Cox, Life of a Universe, Part 2 "End of Days": https://www.youtube.com/watch?v=j-ZhS9Tya-8 at about 16 minutes in.
The explanation in small print above reads: In the standard story, the big bang began with a singularity, an infinitely dense point that gave rise to the entire universe. Singularities are unpredictable, however: the laws of physics break down there and there is no reason to think that one would create the world we see. Instead, the authors postulate that the universe began when a star in a four-dimensional universe collapsed to form a black hole. Our universe would be protected from the singularity at the heart of this black hole by a three-dimensional event horizon. Here we depict the process in 3-D because no one knows what a 4-D cosmos would look like.
At mid-graphic, the 4-D universe is shown in 3-D form, and then the event horizon separating it from the 3-D universe which which we are familiar. The conventional story is then depicted with a singularity, illustrated by a white dot followed by inflation (the black curve), the CMBR, the dark ages and first stars.
One way of testing this hypothesis is by measuring distortions in the CMBR which may have been pulled by the gravitational effect of the four-dimensional black hole. The research here is presently inconclusive and a work in progress. But, assuming for the moment the correctness of the group’s proposed solution, the problems inherent in the big bang are now subsumed by another: where did our universe’s parent universe come from? We don’t yet understand the four-dimensional universe or what it and its features look like, but thanks to our learned authors, at least we now have a hypothesis to explore for answers.
But wait, there's more!
All these issues – the problems with the big bang itself, the horizon problem and the flatness problem are analysed in the Brian Cox documentary Life of a Universe: Part 1 – Creation https://www.youtube.com/watch?v=Or2Itbzxo6A at about 11.30 minutes in, leading to the conclusion that perhaps infinite space is filled with what is known as a scalar field, something like an ocean with built-in repulsive energy causing it to expand, bringing about new universes within, a multiverse in other words, something like holes in a swiss cheese, according to Brian Greene’s colourful analogy. Considered in this way, the big bang was merely an event in a pre-existing universe - not a single event, but part of a continuing process.
The energy within this field is never fully used up and continues to expand inexorably, leading all the while to big bang after big bang after big bang as new bubble universes are brought into being. Within these bubble universes, some ripples in the scalar field ocean are of greater density and intensity than others and collapse into each other, in the process forming stars, galaxies, asteroids and so on.
All this is not idle speculation says Greene. It is firmly grounded in the mathematics of inflationary cosmology. And as these new universes are being created, every possible possibility that can happen does happen and universes are being created many times over and continue being created. Considered in this way, our existence is inevitable, concludes Brian Cox, and inflation is the key. So this is also essentially the story as to how our own universe got going, well at least according to the theory!
But it's also the story about how it ends. As inflation stops, our own universe also grinds to a halt, but others are being constantly created in the process [5].
[1] Explored in Brian Greene, The Hidden Reality – Parallel Universes and the Deep Laws of the Cosmos, Alfred A Knopf, New York, 2011Probing the Mysteries of the Cosmos, August 2013, 37 at 38.
[2] Michael S Turner, “Origin of the Universe”, Scientific American: Special Collector’s Edition: Extreme Physics, Probing the Mysteries of the Cosmos, August 2013, 37 at 38.
[3] For the following material, see Niayesh Afshordi, Robert B Mann and Razich Pourhasanmay, “The black hole at the beginning of time”, Scientific American, August 2014, 27-33. This material represents a synopsis of the main thrust of the article.
[4] Branes are explored in the segment on string theory.
[5] Brian Cox, Life of a Universe, Part 2 "End of Days": https://www.youtube.com/watch?v=j-ZhS9Tya-8 at about 16 minutes in.