Hum,
Here is a small summary of the evolution and beauty of the big bang theory. (As it has not really been properly outlined here).
As I understand it, when the Time = 10^-43 seconds, and the Temp = 10^32K (the Planck epoch), all four fundamental forces were unified and "particles" as we known them could not have existed. Beyond this point, the classical theory becomes meaningless, because our conventional physics breaks-down.
(Sry, no apologies, for my lack of friendly layperson speak – but I have highlighted keywords in bold to be googled)
At this time, it is thought that Gravity and the Strong Force are at the same scale. 1/R2 particles can beis extremely large (R is very, very small), and created from the gravitational field into a 10 dimensional point.
A couple of weird things can happen, for example, one particle can have all the energy of the Universe, and it could be same size as the Universe.
Therefore, even if we had the mathematical tools, I doubt we could really understandb that physics.
Basically, quantum physics tells us that it is meaningless to talk in quite such extreme terms, it is better that we should consider the expansion as having started from a region no bigger across than the so-called Planck length(10^-35m), when the density was not infinite but `only` 10^94 grams per cubic centimetre. (These are the absolute limits on size and density allowed by quantum physics)
At this time, the theory can explain the mechanism; quantum uncertainty.
The idea that the Universe may have appeared out of nothing at all, and contains zero energy overall, was developed by Edward Tryon, New York City University, who suggested in the 1970s, that it might have appeared out of nothing as a so-called vacuum fluctuation, allowed by quantum theory.
Quantum fluctuations would form temporary quantum bubbles, (for example pairs of particles - such as electron-positron pairs) out of `nothing`, provided that they disappear in a short time. The more mass created, the shorter the virtual bubble could exist, and just inside these bubbles, Higgs particles released their energy as they decayed. Supersymmetry was breaking, making the bubble grow.
When the symmetry is broken, forces are decoupled (a phase transition) in a specific manner so that the forces have now separate characteristic.
This defines the physics of our Universe.
It is thought that of the original ten dimensions, 6 compactified, leaving 3 macro-dimensions and one temporal dimension.
(The energy in a space-time gravitational field is negative, while the energy locked up in matter is positive. If the Universe is exactly flat, then the two numbers cancel out, and the overall energy of the Universe is precisely zero. It is also expected that the rotation, and charge, of the Universe is also zero. )
One problem, thought, was as the bubble was gradually filled with energy, and the bubbles of the "true vacuum" (with a nonzero Higgs field) percolate and grew, baryogenesis occuring at or near the bubble walls, the gravity would stop it expanding...
It was a problem encountered with an early version of the theory: that if a quantum bubble (about as big as the Planck length) containing all the mass-energy of the Universe did appear out of nothing at all, its intense gravitational field would immediately crush it into a singularity.
Luckily, development of inflation theory showed how to remove this difficulty and allow such a quantum fluctuation to expand exponentially up to macroscopic size before gravity could crush it out of existence.
Supersymmetry breaking provided the energy for inflation, of course.
For example, at the Planck time, 10^-43of a second, gravity would be created/broken, and by about 10-35 of a second the strong nuclear force.
Within about 10^-32 of a second, the scalar fields would have doubled the size of the Universe at least once every 10-34 of a second (some versions of inflation suggest even more rapid expansion than this).
It would mean that in 10^-32 of a second there were 100 doublings. This rapid expansion is enough to take a quantum fluctuation 10^20 times smaller than a proton and inflate it to a sphere about 10 cm across in about 15 x 10^33 seconds. At that point, the scalar field had crystallized leaving the Universe rapidly expanding so that the influence of gravity would not pull everything back into a Big Crunch.
This give the Universe an outward push (acting like antigravity) while it was a Planck length in size. Such a small region of space would be too small to contain irregularities, so it would start off isotropic and homogeneous. There would have been enough time for signals (travelling at the speed of light ) to have crossed the tiny volume, so there is no horizon problem. In addition, the expansion flattens space-time itself, in much the same way that a balloon becomes smooth, as it is blown-up. If we blow-up the balloon big enough, say the size of the earth, the surface will appear flat.
At this time Supersymmetry breaking is also predicted to have created a few other oddities; cosmic strings are thought to be supermassive relics of this process, forming at phase transitions. Other relic objects from topological defects are also predicted, such as monopoles, textures and domain walls.
In the case of monopoles there should be 10^80 of them out there...
(but we don`t see any - inflation got rid of them)
When the Time = 10^-11 seconds, and the Temp = 3x10^15 k (The GUT epoch) the other three forces remained unified. The small excess of matter that makes up the universe today must have been created during this epoch,
Shortly after the Strong force separates, then the Weak force and the Electrostatic force (which had the same magnitude.)
omega=1
If the Universe starts out with the parameter less than one, omega gets smaller as the Universe ages, while if it starts out bigger than one; omega gets bigger as the Universe ages. The fact that omega is between 0.1 and 1 today means that in the first second of the Big Bang it was precisely within 1 part in 10^60. This makes the value of the density parameter in the beginning one of the most precisely determined numbers in all of science, and the instinctive deduction is that the value is exactly 1.
One important feature of this is that there is a large amount of dark matter or energy in the Universe. Another is that the Universe was made flat by inflation.
[ A common confusion is that inflation seems to violate the faster-than-light rule. Even light takes 30 billionths of a second (3 x 10^-10 sec) to cross a single centimetre, and yet inflation expands the Universe from a size much smaller than a proton to 10 cm across in only 15 x 10^-33 sec. This is possible because it is space-time itself that is expanding, carrying matter along for the ride; nothing is moving through space-time faster than light. Indeed, it is just because the expansion takes place so quickly that matter has no time to move, and the process captured the original uniformity of the primordial quantum bubble. As into what the universe is expanding into is also a bit confusing to the layperson; space-time expands (perhaps I should say `enhances into`) a region that contains no space-time, a region that contains absolute nothing, the Void. ]
The inflationary scenario has already gone through several stages of development during its short history. The first `classical` inflationary model was developed by Alexei Starobinsky, at the L. D. Landau Institute of Theoretical Physics in Moscow, at the end of the 1970s. It was a model based on a quantum theory of gravity, it became known as the "Starobinsky model" of the Universe.
In 1981, Alan Guth, then at MIT, published a different version of the inflationary scenario. Guth came up with the name "inflation" for the process he was describing. There were obvious flaws with the specific details of Guth's original model. In particular, Guth's model left the Universe after inflation filled with a mess of bubbles, all expanding in their own way and colliding with one another. We see no evidence for these bubbles in the real Universe, so obviously the simplest model of inflation couldn't be right.
In October 1981, the Russian cosmologist Andrei Linde presented an improved version, called "new inflation", which got around the difficulties with Guth's model.
The next step forward came with the realization that there need not be anything special about the Planck- sized region of space-time that expanded to become our Universe. If that was part of some larger region of space-time in which all kinds of scalar fields were at work, then only the regions in which those fields produced inflation could lead to the emergence of a large universe like our own. This "chaotic inflation", because the scalar fields can have any value at different places in the early super-universe; it is the standard version of inflation today, and can be regarded as an example of the kind of reasoning associated with the anthropic principle (nothing to do with "chaos theory").
The idea of chaotic inflation led to the next development of the inflationary scenario. A tackling of the singularity and, "before" the singularity. (remember, time itself began at the singularity – so the `before` is not in a temporal sense). Chaotic inflation suggests that our Universe grew out of a quantum fluctuation in some pre-existing region of space-time, and that exactly equivalent processes can create regions of inflation within our own Universe. New universes could bud off from our Universe, and our Universe may itself have budded off from another universe, in a process, which had no beginning and will have no end. A twist on this theory suggests that the process takes place through black holes, and that every time a singularity is formed it expands out into another set of space-time dimensions, creating a new inflationary universe - this is called the baby universe scenario.
Even Darwinian principals can be applied to this process. As new Universes are formed, they (probability) take on the physics of the parent Universe. If the initial conditions are exactly right then the baby Universe will collapse back. This may explains why our Universe is so finely tuned.
There are similarities between the idea of eternal inflation and a self-reproducing universe and the version of the Steady State hypothesis developed by Hoyle and Jayant Narlikar, with their C-field playing the part of the scalar field that drives inflation.
One of the first worries about the idea of inflation (long ago in 1981) was that the process was so efficient at smoothing out the Universe, how could irregularities as large as galaxies, clusters of galaxies and so on ever have arisen? Quantum fluctuations could produce tiny ripples in the structure of the Universe even when our Universe was only 10^-25 of a centimetre across -- a hundred million times bigger than the Planck length.
Observations of the background radiation by a satellite called COBE showed exactly the pattern of tiny irregularities that the inflationary scenario predicts.
The theory said that inflation should have left behind an expanded version of these fluctuations, in the form of irregularities in the distribution of matter and energy in the Universe. These density perturbations would have left an imprint on the background radiation at the time matter and radiation decoupled (about 300,000 years after the Big Bang), producing exactly the kind of nonuniformity in the background radiation that has now been seen, initially by COBE and later by other instruments.
After decoupling, the density fluctuations grew to become the large-scale structure of the Universe revealed today by the distribution of galaxies. This means that the COBE observations are actually giving us information about what was happening in the Universe when it was less than 10-20 of a second old.
No other theory can explain both why the Universe is so uniform overall, and yet contains exactly the kind of "ripples" represented by the distribution of galaxies. This of course does not prove that the theory is correct.
The theory also makes another prediction, that the primordial perturbations may have left a trace in the form of gravitational radiation with particular characteristics, and it is hoped that detectors sensitive enough to identify this characteristic radiation may be developed within the next ten or twenty years.
Another big snag with the simplest inflation models, is that after inflation even the observable Universe is left like a mass of bubbles, each expanding in its own way. We see no sign of this structure, which has led to all the refinements of the basic model. Now, however, this difficulty has been turned to an advantage.
It is suggest that after the Universe had been homogenised by the original bout of inflation, a second burst of inflation could have occurred within one of the bubbles. As inflation begins (essentially at a point), the density is effectively "renormalized" to zero, and rises towards the critical density as inflation proceeds and energy from the inflation process is turned into mass. Nevertheless, because the Universe has already been homogenised, there is no need to require this bout of inflation to last until the density reaches the critical value. It can stop a little sooner, leaving an open bubble (what we see as our entire visible Universe) to carry on expanding at a more sedate rate, into something looking very much like the Universe we live that can arise naturally, with no "fine-tuning" of the inflationary parameters.
All done using the very simplest possible version of inflation, going back to Alan Guth's work, but applying it twice.
In addition, you don't have to stop there. Once any portion of expanding space-time has been smoothed out by inflation, new inflationary bubbles arising inside that volume of space-time will all be pre-smoothed and can end up with any amount of matter from zero to the critical density (but no more)….
Whoops got carried away there…and I haven’t even got to the Ekpyrotic version…
That describes not an infinite point (and gets around the mathematical problems dealing with infinities) but a tiny finite string/membrane (aka 5 dimensional membranes that collided to form the bb)
