Asked in Big Bang Theory (scientific model)
Where did the material for the Big Bang come from?
February 08, 2014 3:28AM
Scientists call the Big Bang a theory, rather than a hypothesis, because it is the best explanation for the facts as we have them. The next stage, if scientists ever get there, is for it to become a law - because there would ostensibly be a long history of unrefuted evidence. Even the hardest scientists would do well to consider 'proof' an elusive goal, and quite possibly a goal that can never really be reached.
If true, the Big Bang applies equally to all people regardless of faith. There was a Big Bang, and over billions of years the universe formed, the earth coalesced, life began and evolution took over, until we have the life forms we have today. Faith based systems usually include a creation event; systems not involving a faith element are usually content to watch knowledge develop and deepen over time. The only difference is whether there was divine intervention.
As to where the materials came from, before there were materials (in other words atoms and molecules), there were subatomic particles. And before there were subatomic particles, there was pure energy. We know we can convert energy into matter and back again - the only requirement being that it is done in accordance with the laws of conservation.
One hypothesis, consistent with all current knowledge, is that the primal energy came from a false vacuum that formed by means of a random quantum fluctuation.
I don't know. Isn't that elegant? I think one day we will know, and I have my own ideas, but at this time, we just don't know. Faith-based systems usually include some assurance of a creation event; secular systems do not operate from a position that creation is a given that must be accommodated by any subsequent explanation.
One of the hardest things to comprehend and reconcile in cosmology is the 'free lunch' factor - how it comes to pass that the universe can get something for nothing; how it can go from not existing, to existing; how matter or energy can come into being from its former non-existing state. To be fair though, cosmology is not the only worldview suffering from this dilemma. Any account of supernatural creation, also leaves the existence of its creator unexplained. Even then, it has resorted to the assumption that supernatural powers exist and natural laws are subject to inexplicable violations.
For any sensible secular attempt to explain the origins of the cosmos, we must proceed from what is known and seek to explain what is unknown without ceding to assumptions or contradictions. A good starting point is to observe that the universe does indeed exist. If it didn't we wouldn't be here contemplating it. It then follows that something had to begin existing or else we must assume that something existed for an eternity into the past. [The assumption that there can be no physical reality extending into the indefinite past may be a human bias based in our innately illogical wiring.]
The eternity idea, when applied to cosmological science, seems to be irreconcilable with direct evidence. The universe does appear to have a finite beginning in the past. This so called 'Big Bang' is much more subtle than our intuitive imaginations tend to picture it. It is not simply matter exploding into a preexisting void.
The big bang was actually predicted by Einstein's theory of relativity, in which time and space are aspects of the same thing 'spacetime'. The implications of this are less intuitive than most people realize. To have an appreciation of cause and effect, so that we can say "this was caused by that" we also rely on a concept of linear time, because each effect must be preceded by a previous cause. The perfectly sensible question of "but what caused that?", ultimately leading to the current question regarding the cause of all the matter in the universe, relies on the assumption that time existed before that matter. OK, it did, but the matter is only a manifestation of energy (again according with relativity), but that just pushes the question back to "where did the energy come from?" What is needed is a primal cause of all causes. Unless time itself breaks down and the concepts of 'before' and 'after' become meaningless.
When cosmologists say that the universe is expanding, they do not mean that the galaxies are rushing into a preexisting void. What they mean is that spacetime itself is expanding and increasing the relative distance between galaxies like raisins in an expanding raisin loaf. The implications of relativity for the big bang, is that time and space are properties of the universe that themselves began with the big bang. In conceptual thought and natural language this is hard to intuitively describe and comprehend, but in the language of mathematics, it seems the natural and inevitable consequence of the known evidence.
If the universe is expanding this way, then by running the clock backwards and inquiring into past epochs, we must conclude that the universe becomes smaller and smaller as we look further and further into the past. This is not hard to do in cosmology incidentally, because light travels at a finite speed and what we see from distant objects is delayed by the traveling time for light (approx. 300,000 km/sec).
The further away the object, the more ancient the light is that we are presently receiving from it. We are actually looking back through time as we look out through space.
Traversing the eons back through 13.7 billion years we come to a point where time and space cease to exist. Running the clock forward again we pass through a moment at the beginning of time where the universe is no bigger than an atom. At this point in history or prior, time and space become indistinct and it gets worse. Below the Plank constants, the entire universe is subject to quantum fluctuation. Quantum mechanics is another area that is full of counter intuitive but mathematically beautiful ideas.
So where did matter come from? It came from a free exchange with energy for particles. But as for the ultimate cause of all causes, we must assume that something was permitted to begin existing without cause, otherwise nothing could begin existing in the first place and at the first time. In this view, causality itself, was also born in the big bang. Without spacetime it is meaningless to speak about prior causes, because without spacetime, no linear progression of time from the past into the future is possible. It may be desirable to explain where this matter manifesting energy came from, but the question assumes that it is sensible and meaningful to ask a question about causality, in a situation where no prior causes are possible.
A relatavistic metaphor for this, honoring spacetime, is that below a certain size, the universe has no space for a past. Its entire volume was consumed at first by that primordial present moment. The only reason it found room for a future, is by expanding rapidly and dragging the present moment away from the past. The energy required to fund this expansion and the subsequent formation of matter is not justified by causality. because it existed at the birth of the universe, before which there was no time or causal relationships. On the other hand, the "free energy" can not be prohibited by causality either, as, by the same token, there were no causal relationships to prevent the "free energy" either.
Intuitively, we expect to find a cause for everything, but if we think about it carefully we must realize that this can not apply to absolutely everything. Something must initially exist without cause. There is no logical contradiction, or violation of natural law, if there is no natural law which prevents the spontaneous appearance of something. In our day to day lives at the human scale of existence, it would seem ludicrous for a chair to spontaneously pop into existence before our eyes. A chair is certainly the kind of object that must be made of other materials, by way of cause and effect relationships orchestrated by human minds. But what about a rock? again rocks are formed by geological processes, that have natural cause and effect relationships which in turn obey the laws of nature. We must then ask, how the rock manifested itself, bypassing the known laws of physics which create rocks.
Energy is much more nebulous and plastic. It is easily transformed from one state into another. We may use light to create electricity for instance, or heat to produce kinetic energy etc etc.. But ultimately we know that no energy is destroyed or created. it is just transformed from one form to another. This is called the principle of energy conservation. We know there are natural laws which make this principal inviolate. It is no coincidence of nature that energy can neither be destroyed or created. But those laws depend for their meaning an inviolability on cause and effect relationships within spacetime. No law was broken in the big bang, because no extra energy suddenly appeared in the universe, the energy appeared with the universe.
We might like to know why the universe began at all. According to the modern understandings, it was neither compulsory or impossible, but how probable was it? This is also a moot point, because there may be multitudes of such universes. Given that spacetime is born into the universe, these universes would exist outside of our space and time coordinate system, so there would also be no meaning to whether they exist before, after, or simultaneously with ours. Remember this when you are tempted to think that our own existence is unfathomably improbable. However improbable anything in our universe may seem, given a potentially infinite number of possible universes some of them (perhaps scores of them), may quite easily have the quirky improbable characteristics we find in our own Universe.
As alluded to above, there was no matter as we know it in the time leading up to the big bang, but there was a concentration of energy that began to expand at some point. After thinning and cooling, particles began to condense. The rest is history.
It is interesting that people usually have no problem accepting the possibility of time unfolding into an endless future, but have a huge difficulty going in the other direction. The problem may be that the idea of things existing into an endless past is beyond our intelligence, wit and imagination. This difficulty might arise because 'anthropomorphizing' cosmology is simply irresistable to us. We have a beginning, and many of us are sure that we will enjoy existence for endless future ages [alternately, we have difficulty accepting that our existence could somehow completely end], and so logic notwithstanding we conclude that the cosmos must be the same. In reality, our concept of an endless future is every bit as dim and unsupportable by observation as is our conviction that an endless past is utterly impossibe.
Some theorists are considering the possibility that our universe began at the collision of two nearby universes, mathematically constructed as 'membranes' [an offshoot of superstring theory]. There may be countless other universes, many or all of which overlapping with our own. They may simply exist within the folded dimensions locked in the quantum world of the tiny. Of course, this might not be the case, but there are mathematical models that support the possibility. It goes without saying that such models offer hope that we might speculate about conditions prior to the big bang, and that we might one day shed the taboo of the forever indefinite past.
A natural scenario, that is not yet a scientific theory but is consistent with all current knowledge, explains the origin of our universe without the added hypothesis of supernatural creation:
By means of a random quantum fluctuation the universe 'tunnelled" from pure vacuum to what is called a false vacuum, a region of space that contains no matter or radiation but is not quite nothing. The space inside a bubble of false vacuum is curved, or warped, and a small amount of energy is stored in that curvature. This ostensible violation of energy conservation is allowed by the Heisenberg uncertainty principle for sufficiently small time intervals.
The bubble then inflated exponentially and its curvature energy transformed into matter and radiation. Inflation stopped and the more linear big bang expansion commenced.