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Ashtekar's team at Penn State has been running cosmological BOUNCE simulations on the computer, studying many different cases.
A certain critical mass-energy density has emerged as important.
It does not depend on the value of the cosmological constant (some of their simulations are of realistic universes in the sense of having a positive cosmo constant)
It does depend on the value of the LQG immirzi parameter. The preferred value here is gamma = 0.2375
in case after case, whatever the particular detailed assumptions, when there is a contracting QG universe it will contract until the density is 82 percent of Planck density, and then (quantum gravity becoming repellent at high density) it will bounce, and re-expand.
Shouldn't we call this critical density the Ashtekar density?
A certain critical mass-energy density has emerged as important.
It does not depend on the value of the cosmological constant (some of their simulations are of realistic universes in the sense of having a positive cosmo constant)
It does depend on the value of the LQG immirzi parameter. The preferred value here is gamma = 0.2375
in case after case, whatever the particular detailed assumptions, when there is a contracting QG universe it will contract until the density is 82 percent of Planck density, and then (quantum gravity becoming repellent at high density) it will bounce, and re-expand.
Shouldn't we call this critical density the Ashtekar density?