On Thu, Jun 23, 2016 at 11:57 AM, Brent Meeker <[email protected]> wrote:
>> >> >> what is clear cut is that the chain on "what caused that?" questions >> either comes to an end or it does not. > > > > > Explanation and cause are conceptually different. > Not if you want an explanation of what caused that. > > in fundamental physics "cause" has disappeared because the theories are > time symmetric. > Actually we know of one fundamental law that isn't time symmetric, a movie of neutral kaon decay would look slightly different if run forward rather than backward, but not if you looked at the backward running film in a mirror and you assumed the electrical charges were reversed. CPT (Charge Parity Time) symmetry still holds true as far as we know. But more important than that even if the laws of physics were time symmetric that wouldn't be enough to conclude that physical systems evolve in a time symmetrical way because that would also depend on initial conditions. Entropy always increases because there are more ways to be high entropy than low, so if the universe started out in a very low entropy state then entropy will increase and time will have a direction even if the laws of physics don't. That's why we can remember the past but not the future. > > > A causal theory now is just means one where no information can be > propagated faster than c. Explanation, on the other hand is a subjective > linking of ideas that leads from something you don't understand to > something you do. > So one idea CAUSES you to understand another idea. John K Clark > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
