More Matt Strassler (Introduction)

by David Turell , Wednesday, March 26, 2014, 13:24 (3895 days ago) @ David Turell

Note my bolded area. It allows you to believe what you want without any sense of a proof:-"So if people tells you that the universe started in such and such a way, perhaps "with a singularity" or "with a quantum fluctuation out of nothing" or "in the Big Crunch (i.e. the collapse) of a previous phase of the universe", remember that they're telling you about the red zone. They're neglecting to tell you that what they're saying is pure theory, with neither an experiment to back it up nor a clear theoretical reason to believe their suggestion is unique and preferable over someone else's alternative. Only a bit later in cosmic history, once we focus on the late stages of inflation, and forward in time from there to nucleosynthesis, do we have both data (cosmological observation and particle physics collisions) and reasonably reliable theory (Einstein's theory of gravity plus the Standard Model of particle physics). Our confidence grows as time moves forward, the observable patch of the universe cools, and physics becomes of a sort that we've tested in numerous experiments already.
 
"From this, I hope that you can see that the Big Bang Theory really isn't a single, undifferentiated structure. The most reliable part of the theory is that there was, at one point, a Hot stage of the Big Bang. (Some people call that the Big Bang, in fact.) If BICEP2′s measurement is accurate, and correctly interpreted, then the reliable portion of the theory may then include a period of inflation that preceded the Hot Big Bang. (Some people would call "inflation plus the Hot Big Bang" the "Big Bang".) But anything before inflation is not in the least reliable... in particular, the notion that the universe's heat and density increased to the extent that Einstein's equations have a singularity, presumably indicating that they're not sufficient to describe what was going on, is an assumption"-
http://profmattstrassler.com/2014/03/26/which-parts-of-the-big-bang-theory-are-reliable/