Energy density at the point origin of the Universe I would like to add to some points made earlier by Crisp and others in this discussion about comparisons of the energy density in the early universe and in the beam of particles at Fermilab. In a very readable little book called 'The first Three Minutes' by Steven Weinberg (Nobel prize in physics) he describes the conditions of the universe shortly after the big bang. The earliest he believes we can really describe is 0.01 seconds. At that time the temperature was 1E11 degrees K and the energy density was 21E41 eV per cubic cm. The Fermilab beam is made of bunches of protons and antiprotons traveling in opposite directions. The highest energy density in the beam is when one bunch (2.7E11 protons) overlaps with a bunch of antiprotons (3.0E10 antiprotons). The length of a bunch is about 8 nanoseconds which at the speed of light is 240 cm long. Some of these data come from the reference in my earlier post, but the others came from other spots on their website. They are able to focus the cross-section of the bunches down to 0.015 cm by 0.015 cm. The better the focusing the more interactions there are between the particles. The energy per particle is 1E12 eV (1 TeV). Paul Dixon's value of 1.8 Tev is correct for two particles colliding head-on before the upgrade (0.9 + 0.9 Tev). Since the upgrade the values are now 1.0 + 1.0 TeV. So the energy density for two colliding bunches is 3.0E11 particles times 1.0 TeV per particle divided by the volume (240 cm * 0.015 cm * 0.015 cm). Fermilab beam: 5.6E24 eV per cubic cm. Early universe: 21E41 eV per cubic cm. The energy density of the early universe is over 17 orders of magnitude larger than the Fermilab beam.