Earlier quoted context omitted.
No, 13 billion years is the age of the universe. The observable universe is a sphere with a diameter of ~93 billion light years (And is likely to only be a subset of the entire universe).
I have a question: Just over 20 years ago when the accepted view was that the expansion of the universe was slowing down, would you have backed that position with as much certainty as you are backing this one? That the universe is a mere 13.7 billion years old? We cannot prove the absence of light in a place that is already so far away that it's light will never reach us. Do you agree? We can prove what we can observ…
Was it ever a mainstream view? I thought it was just a conjecture, leading to the 'big crush', and was disproven long ago, way more than 2 decades ago.
> The entire premise of dating our universe is based on its observed rate of expansion
Also there's the cosmic microwave background radiation. We have mapped it, and this has also allowed us to corroborate when the universe has formed, what temperature it had, and when large scale structures appeared.
There's probably other sources that allows us to estimate the age of the universe.
> how can anyone be sure that it was the first and only Big Bang?
We can't. But it is an irrelevant conjecture outside of philosophy, we can't observe anything before the big bang.
> but in fact it's more likely that many Pangea's have come and gone in various states as the planet roils on
Sure, but that's a planet. We can't extrapolate much from that and apply to the universe at large.
> Perhaps the Big Bang was merely a "localized" event and there are Big Bangs occuring in distant places whose light will never reach us
Unobservable, therefore unfalsifiable, therefore unscientific. Philosophy again.
> imagine that the universe has already been through a near infinite number of Big Bang / Big Crunch cycles
Unless the rate of expansion starts to slow down or we have indication that it will ever reverse, there's no big crunch. The rate of expansion is increasing
> currently accepted theory is akin to believing that the Earth is the center of the universe and the sun revolves around us
Not really. You are dismissing generations of people dedicated to the study of these things. We have a pretty good idea of what's going on based on the scientific method, not conjectures from single individuals.
There are things that we don't know yet. On a macroscopic scale, dark matter. Things don't really behave as they should based on observations, so this is why we have dark matter as a hypothesis. There could be another mechanism, research is ongoing. But as far as the macro universe goes, that's the major thing we don't understand yet.
Most discoveries will likely come from a better understanding of the 'building blocks', of which quantum physics is at the forefront.
There's probably much more we don't know yet. But the age of the universe, as we observe it, is not among them.