@Meow Mix
And you Made similar points, so my responses to her also apply to you, (if you think I ignored a relevant point made by you please let me know
But if the universe is past eternal, it remains inexplicable why our fields decayed 13.8B years ago to produce our big bang.
If the universe is past ethernal then any field that existed would have decayed an infinite amout of time ago.
An analogy would be imagine that you are playing poker since infinite past, given this I would conclude that you got your first “full house” and infinite amount of time ago, it makes no sense that you got your first “full house” 13.8 billions years ago (nor at any point in the finite past)
If you're playing poker for an infinite amount of time, then at any time you could still get a royal flush: it doesn't matter whether the one 13.8 billion years ago was the "first" one or not.
As for your other questions, perhaps a better explanation of eternal inflation is in order. Imagine a circle (we will ignore for a moment that it is a finitely sized circle, this is just to simplify the concept enough to understand). Now imagine that this circle is expanding (ignore for now that things would have to exist in order for expansion to mean anything, again, this is just to show a particular concept. Trying to pre-empt objections to the analogy).
Now, let's say that the field causing this circle to expand spontaneously decays at one of the edges and begins to expand much more slowly. So what you're imagining now is a nearly complete circle with a little dimple. Now, because the rest of the circle is expanding so much faster than the little dimple, the circle-material wraps around the dimple-material as the circle continues to expand: now you have a circle with a smaller circle (that used to be the dimple) inside of it: a bubble.
Now, the circle continues expanding. More dimples are made, and enveloped. You end up with a very large circle with a great many bubbles inside of it. As you can see, even though parts of the circle decay to make slowly expanding bubbles (relative to the circle), there will always be more circle than bubble, and the circle will never completely decay because only parts of it decay (and the rest expands to make up for it).
Now, in the real world, energy is conserved here because the expansion is balanced against the now-existent gravitational potential of the bubbles.
My problem is not the claim that inflation (or even eternal inflation is true) for the sake of this discussion we can assume that such model is true.
The issue is that all the observable universe seems to have low entropy while your model of “infinite past” predicts high entropy (nearly 100% entropy) even in eternal inflation entropy on average always increases so low entropy is not expected to be seen.
Entropy is temporal, and temporality is entropic. As has been stated above, every bubble creation is a local entropic minimum (that means the arrow of time begins in the bubble). Entropy winds down from there. But can you see how the arrow of time beginning in a bubble is not an ontological beginning?
Given that our observations contradict your predictions you have to go beyond science and speculate a lot……. For example under your view our observable universe should be just a small grain of sand compared to the whole universe, such that the observed low entropy would be just a statistically insignificant exception.
But talking about the second law my biggest objection to an infinite past would be that the universe would be dominated by Boltzmann brains, Boltzmann brains would be the most typical and abundant type of observer…. So your world view forces you to conclude that you are a Boltzmann Brain. You must conclude that all your observations your memories and even this conversations are just an illusion. Paradoxically all your evidence for “inflation” would also be an illusion.
So the way I see it ether
1 you are a Boltzmann brain
2 the universe is not past eternal
Honestly I see this as a devastating objection to any godless model that includes infinite past and/or infinite (or many) worlds , any opinion on that?
The Boltzmann Brain issue is not an issue: in order for that argument to work, the universe must still be geared towards favoring the creation of such a thing; and the universe is not. It is not true that given an infinite universe and infinite time that the likelihood for all things developing is equal: we would probably smirk at the suggestion that the most likely object to exist is a green bust of Julius Caesar after all, and that's because of the physics. In order for the Boltzmann Brain objection to have any bite, Boltzmann Brains must be highly probable outcomes of the universe's physics; and they just aren't.
well quote from Guth
I might be wrong but at least as a layman it seems obvious to me that these scientists are claiming and concluding that eternal inflation can’t be “past eternal” am I missing something?
What Guth, Vilenkin, and Borde are saying is that classical methods of probing the Planck era give finite geodesics by necessity (in the same way that classical approaches to thermodynamics give us singular results like the ultraviolet catastrophe). Their phrasing is intended for colleagues that understand the context of their statements, which is that you cannot use classical physics to probe the Planck era: it is a consequence of the choice of metric. It does not mean that there was an ontological beginning, as at least Vilenkin and Guth have gone on to clarify when laypersons became interested in their papers.
In physics, sometimes you get singular results (e.g. event horizons, singularities) because of your choice of metric and assumptions. If you say "it is impossible to get past the event horizon," what your colleagues understand is that you are using the Schwarzschild metric and not Eddington-Finkelstein metric (the first is singular at event horizons, while the latter is not). It's because of the choice of metric, not because of any fact about reality. And that is what Vilenkin et al have shown: that we need quantum gravity to probe the Planck era; classical metrics won't cut it.