Big Bang Big Bounce

Inflation, quantum cosmology, and the anthropic principle

“…Furthermore, in order for life as we know it to exist, it is necessary that the universe be sufficiently large, flat, homogeneous, and isotropic. These facts, as well as a number of other observations, lie at the foundation of the so-called anthropic principle (Barrow and Tipler, 1986;Rozental, 1988;Rees, 2000) According to this principle, we observe the universe to be as it is because only in such a universe could observers like ourselves exist.…”

The fundamental constants and their variation: observational and theoretical status

“…It just tells about the stability in a neighborhood of the location of our universe in the parameter space of physical constants. Rozental (1988) argued that requiring that the lifetime of the proton τ p ∼ α…”

“…It just tells about the stability in a neighborhood of the location of our universe in the parameter space of physical constants. Rozental (1988) argued that requiring that the lifetime of the proton τ p ∼ α −2 EM (h/m p c 2 ) exp(1/α EM ) ∼ 10 32 yr is larger than the age of the universe t u ∼ c/H 0 ∼ 10 17 s implies that α EM < 1/80. On the other side, if we believe in a grand unified theory, this unification has to take place below the Planck scale implying that α EM > 1/170, this bound depending on assumptions on the particle content.…”

“…They are illustrative and give a hint that the constants may not be "random" parame-ters without giving any explanation for their values. Rozental (1988) also argued that the existence of hydrogen and the formation of complex elements in stars (mainly the possibility of the reaction 3α → 12 C) set constraints on the values of the strong coupling constant. The production of 12 C in stars requires a triple tuning: (i) the decay lifetime of 8 Be, of order 10 −6 s, is four orders of magnitude longer than the time for two α particles to scatter, (ii) an excited state of the carbon lies just above the energy of 8 Be + α and finally (iii) the energy level of 16 O at 7.1197 MeV is non resonant and below the energy of 12 C+ α, of order 7.1616 MeV, which ensures that most of the carbon synthetized is not destroyed by the capture of an α-particle (see Livio et al, 2000).…”