Past Hypothesis Taxonomy
Let me try an experiment: using a blog post to develop a taxonomy. Here I'll try to develop a list/taxonomy of (at least semi-coherent) answers to the question I posed yesterday: why is it harder to formally predict pasts, versus futures (from presents)? Mostly these are explanations of the "past hypothesis", but I'm trying to stay open-minded toward a wide range of explanations.
I'll start with a list of answers, and then add more and group them as I read comments, think, etc. I'll feel free to edit the post from here on:
Extremely unlikely:
Reality isn't different; we just ask different future vs. past questions.
An outside "God" intervened to make our past different.
We live after a big local ebb (i.e., fluctuation) in matter.
Rather unlikely:
Quantum measurement has a local time asymmetry that makes big effects.
A weak local time asymmetry in matter accumulates to big effects.
A past ebb in spacetime shape (e.g., inflation) forced a big matter ebb.
All spacetime boundaries satisfy a law-like "low entropy" condition.
Unlikely:
Our expanding cosmos violates one-to-one state mappings across time.
Past and future have different spacetime law-like boundary conditions.
Robin, looking for counter-examples is a useful technique for understanding and judging claims that are not backed by formal arguments, which I admitted are not available. You don't have to prove to my satisfaction any counter-examples you might find. Feel free to state them informally, or just use them to privately update your own beliefs. And as far as I can tell, the claims under discussion are already stated in simple language that doesn't require any specific focus to understand.
Wei, your area is not my focus, so I'm not going to take the time to prove a counter-example, or even to figure out what you mean precisely enough to know what to you would count as a count-example. It is up to the proponents of such claims to offer arguments in their favor.