G
G asked:

where can i find this description made by steven weinberg? In the beginning there was an explosion, and in three minutes, 98% of the matter there is or ever will be was produced. We had a universe.

Akinbo Ojo Interesting question on an interesting book by a well acclaimed physicist and author. However as Roger Penrose says in his forthcoming book, Fashion, Faith, and Fantasy in the New Physics of the Universe, this account of the universe’s history contains its own share of fantasy. In this regard, I point out one, which is an attempt to make the universe materially wealthy overnight… a fantasy to get-rich-quick.
If cosmologists decide to be greedy and fantasize the acquisition of all our current material wealth within three minutes, i.e. ~10^52kg (~10^69J), given the standard model expansion rate, our universe will be about 5.4 x 10^10m radius (with volume ~ 6.6 x 10^32m^3), giving us an energy density of ~10^36 J/m^3 (~10^19kg/m^3) at this time. This energy density translates to temperatures about 6.6 x10^12K and ambient energies of ~669 MeV, which is so much higher than can permit the formation of nuclei for deuterium (binding energy <2.2 MeV, ~10^10K) and helium (binding energy < 28.3 MeV, ~10^11K) and the Big bang nucleo-synthesis model will collapse.
If however, we allow Mother Nature to build the universe gradually, according to Hypothesis 1 in the book, Hypotheses Fingo to wit;
"The Universe is increasing in mass and radius from an initial zero value in accord with the formula M = rc^2/2G which amounts to about 6.75 x 10^26kg per metre change in radius (and about 2.02 x 10^35kg per second)",

the mass of the universe will be about 3.6 x10^37kg (~ 3.24 x10^54J) at the end of the first three minutes, and not 10^52kg. This being so, given the volume (i.e. 6.6 x 10^32m^3) the energy density will be 4.9 x10^21J/m^3 at three minutes and the corresponding temperatures and ambient energies for the energy density will be ~10^9K and 0.1 MeV (~10^-4 GeV) respectively, just the right temperature for Mother Nature to cook us a perfect dinner of hydrogen-helium nuclei soup where both nuclei are stable.
*For reference, see Wikipedia: Chronology of the universe, https://en.wikipedia.org/wiki/Chronol... and also Hyperphysics website, http://hyperphysics.phy-astr.gsu.edu/... for the timelines. And for formulae that relate energy density within a given volume to the temperature using blackbody radiation laws which can be used to calculate the matter-energy content at different epochs, see http://hyperphysics.phy-astr.gsu.edu/.... Same formulae are used to estimate the 10^32K temperature at the Planck epoch from the Planck density and are still applicable at three minutes. Further discussion can be found in Hypotheses Fingo, see http://www.goodreads.com/book/show/30...
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