I am wondering whether discussions of inflationary cosmology in these forums generally includes or explicitly excludes prior Plank era and GUT era dynamics. I never gave it any thought until reading the following. The Wikipedia article provides a perspective I just don't remember from other sources. If inflationary cosmology excludes Planck and GUT eras, are there some alternative pre inflationary dynamics we are supposed to associate with inflation? http://en.wikipedia.org/wiki/Chronology_of_the_universe [my boldface emphasis] ok [again my bold] Why is the age of the universe less certain when we stick in inflation??