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.
- Our expanding cosmos violates one-to-one state mappings across time.
- Past and future have different spacetime law-like boundary conditions.