Editing Anthropic principle (section)

=== Cosmic inflation ===
{{Physical cosmology}}
{{Main|Cosmic inflation}}
[[Don Page (physicist)|Don Page]] criticized the entire theory of [[cosmic inflation]] as follows.<ref>{{Cite journal |first=D.N. |last=Page |year=1983 |title=Inflation does not explain time asymmetry |journal=Nature |volume=304 |page=39 |doi=10.1038/304039a0 |bibcode=1983Natur.304...39P |issue=5921 |s2cid=4315730 }}</ref> He emphasized that initial conditions that made possible a thermodynamic [[arrow of time]] in a universe with a [[Big Bang]] origin, must include the assumption that at the initial singularity, the [[entropy]] of the universe was low and therefore extremely improbable. [[Paul Davies]] rebutted this criticism by invoking an inflationary version of the anthropic principle.<ref>{{Cite journal |first=P.C.W. |last=Davies |author-link=Paul Davies |year=1984 |title=Inflation to the universe and time asymmetry |journal=Nature |volume=312 |page=524 |doi=10.1038/312524a0 |bibcode=1984Natur.312..524D |issue=5994| s2cid=4307546 }}</ref> While Davies accepted the premise that the initial state of the visible universe (which filled a microscopic amount of space before inflating) had to possess a very low entropy value—due to random quantum fluctuations—to account for the observed thermodynamic arrow of time, he deemed this fact an advantage for the theory. That the tiny patch of space from which our observable universe grew had to be extremely orderly, to allow the post-inflation universe to have an arrow of time, makes it unnecessary to adopt any "ad hoc" hypotheses about the initial entropy state, hypotheses other Big Bang theories require.