I'm sure someone's already thought of that and shot it full of holes though.
Weird side idea could this huge burst of energy that would be released from that be the Big Bang?
η = (n_baryons - n_antibaryons) / n_photons
where the n_species are the number densities of those species. Since baryon number is additively conserved, the asymmetry now reflects the asymmetry in the past.
From WMAP we estimate η ~ (6±0.25)E-10. The question is: why is this SO damn small? There was alllllllmost a perfect cancellation. But not quite. What gives?
On the other hand, it's not QUITE as early as you hope---the anti/baryon annihilation is to light particles and radiation, not the negative pressure needed to cause inflationary Big Bang cosmology.
We don't think this way anymore because we're fairly sure inflation occurred, and its exponential expansion rapidly dilutes away any initial asymmetry. So we need a way to generate asymmetry after inflation ends.
The same time matter started existing. According to our best current models, that was at the end of inflation, when the energy that had been stored in the inflaton field (the field that was driving inflation) was transferred to the Standard Model fields (leptons, quarks, and gauge bosons). This process is called "reheating" (somewhat of a misnomer since it was really the first "heating" of the SM fields).
The most natural expectation is that reheating would have populated matter and antimatter fields (i.e., quarks-antiquarks, leptons-antileptons) equally. Then, as the universe expanded and cooled, the matter and antimatter would gradually annihilate, producing radiation (mainly photons). If matter and antimatter fields had really been populated equally at reheating, this process would have left nothing but photons within a fairly short time (a fraction of a second) after the Big Bang. "Local imbalances" might have made that time a somewhat larger fraction of a second, but it is not at all plausible that they could have lasted for billions of years and allowed a region the size of our observable universe to have essentially no antimatter at all but billions of galaxies' worth of matter.
Since our observable universe does have essentially no antimatter and billions of galaxies' worth of matter, one of two things must have been the case: (1) reheating did not populate the matter and antimatter fields equally, or (2) there was some asymmetry in the interactions involved that created a slight excess of matter over antimatter. As I understand it, most physicists believe (2) to be the case, although it is not known exactly what the asymmetry was.
> could this huge burst of energy that would be released from that be the Big Bang?
No. The energy had to be put in to the matter and antimatter fields first. See above.
I mean it in the sense of an SI second, which is defined in terms of a certain number of cycles of light of a certain frequency that comes from a certain energy level transition in cesium atoms.
> is this second somehow longer because of the huge gravity?
No. The concept of "gravitational time dilation" is not applicable in the circumstances we are talking about.
> was there gravity at all?
"Gravity" is an ambiguous term. On average, the universe is homogeneous and isotropic (and was even more so in the very early universe), which means that on average the matter in the universe exerts no net gravitational force on any particular piece of matter, such as us here on Earth or a tiny parcel of matter in the early universe. In that sense there is "no gravity" in a homogeneous, isotropic universe.
However, the presence of matter and energy certainly affects the spacetime geometry. In that sense, there is "gravity" present.
(I'm asking totally in ignorance. This stuff fascinates me but I don't know nearly as much about it as I wish I did.)
