> inflation necessarily predates big bang
A tangent, but how can anything pre-date the big bang? Time itself is supposed to have been created at that point. Did you mean inflation necessarily follows a big bang?
A tangent, but how can anything pre-date the big bang? Time itself is supposed to have been created at that point. Did you mean inflation necessarily follows a big bang?
Our space-time began at the big bang. Even decades ago, Stephen Hawking was talking about it like "Since events before the big bang can have no observational consequences, we might as well leave them out of our discussion and simply say that time began at the big bang."
You are making a very strong assertion that something did carry through - what are you basing that on?
"Might as well not" is different from "Did not". That's all I, and Mr Hawking, are saying. In fact, your first sentence is literally just a paraphrase of my quote from Hawking.
> You are making a very strong assertion that something did carry through
No, I most certainly did not.
All I said is, there could have been something, or could have not been. I did not say something did happen prior to the big bang, just that it is wrong to say that it could not have.
There are people working to disprove this. There is a concept floating around that the CMB might contain evidence of something from before the BB. If our universe came into existence within some other universe, then arrangements of large gravitational objects in that universe may have some impact on the early formation of our 'pocket' universe.
There was an article on it here on HN, almost certainly within the last month. I don't recall more.
- Naïve extrapolation of GR backwards in time results in a singularity at a finite point in time. Call that the big bang singularity (at t = 0)
- Using current accepted theory, we're able to simulate what was going on at t > 10^-32 or so. Before this, the implied densities and temperature are beyond what our theories can handle and we're less confident about how we got to that point (with an excess of baryons, smooth distribution of energy and matter, and the other parameters that obtain in our current universe).
- Inflation is one of the favored explanations for what happened before, but it doesn't address its own cause ("what happened before inflation?"). There's a theory of "eternal inflation" (local regions that have stopped inflating surrounded by regions that are still inflating), which explains the fine-tuning problem (each region that has stopped inflating can have its own fine structure etc). This is less accepted, maybe this is what you're thinking of?
- There's a push to redefine "the big bang" as all the stuff we can explain with current physics, i.e. as starting after inflation (but still using t=0 at the big bang singularity everyone's pretty sure doesn't actually exist). Or maybe it's been like that for a while and it's just pop science that perpetuates the big bang = singularity idea. Like how relativistic mass has fallen out of favor as a concept.
https://news.ycombinator.com/item?id=28851641
I can't tell whether this is just, "Actually having started with the Big Bang implies a singularity, which isn't allowed, so let's assume it wasn't a singularity and take what we get then."
You could do some extrapolation on the expansion of the universe and just say that yes, there was a point zero, 10^-32 seconds before the earliest point in time that our models can understand, and that's where everything started from a singularity. But then we are still left with a short period of time at the start, where some physics happened that we don't have a working model for.
So since an extrapolated expansion of the universe from a singularity doesn't work in our currently understood models (at least not in the very earliest part of that timeline), is it not then plausible that something other than that expansion from a singularity could have happened during this early unknown period of time?