To the less well acquainted, inflation theory seems like a rather far fetched proposal. It makes very specific claims about the earliest moments of the universe, without being explainable in terms of well established physical theories, e.g. QFT or GR (correct me if I'm wrong). Specifically, it suggests rapid expansion of space in the first $\sim 10^{-33}$ seconds after the big bang. That is a very very short time, billions of years ago, to make such a strong claim about a large, formative event of our universe.

I understand there exists evidence ( such as large scale inhomogeneity ), but couldn't this be explained with a simpler model? Are there competing theories that also explain evidence used to support expansion theory?

In short, help a skeptical non-cosmologist understand why this theory is so strongly supported.

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    $\begingroup$ Google will help you discover that it is not universally supported. One of the originators of the theory, Paul Steinhardt, now rejects it. The reasons for his objection is not that it is far fetched, but rather that it has no explanatory value. You can read his thoughts on the matter in several places. Here's one place, a Scientific American interview. $\endgroup$
    – garyp
    Sep 12, 2016 at 14:01
  • $\begingroup$ @garyp thanks for the link. It's one of those theories I hear about so often but only the gloss, and I've never been satisfied. I'd looking for someone in-field to comment on it - one step beyond e.g. wikipedia or scientific american. $\endgroup$
    – anon01
    Sep 12, 2016 at 14:06
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    $\begingroup$ Possible duplicates: physics.stackexchange.com/q/1030/2451 and links therein. $\endgroup$
    – Qmechanic
    Sep 12, 2016 at 14:56
  • $\begingroup$ Possible duplicate of: What is the evidence for Inflation of the early universe? $\endgroup$ Sep 12, 2016 at 14:59
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    $\begingroup$ @CountTo10 yeah... ouch! $\endgroup$
    – anon01
    Sep 12, 2016 at 16:35