I think we have very few measurements of the arrow of time beyond "contingent ones" like - expansion of the universe, entropy increase, radiation etc. All we have that arises from the laws of physics is the famous CPT violation (I think it is?) of certain mesons. So it's problematic to even say what "reversing time" means except for reversing the contingent arrows, which appear to arise from the expansion of the universe, which may itself be contingent (not required to expand in a particular time direction by the laws of physics, assuming a multiverse or string landscape or whatever). Of course eternal inflation puts the arrow of time into the laws of physics, so it may be there, just beyond out ken, so to speak.
On 7 November 2014 08:16, Bruno Marchal <[email protected]> wrote: > Hi Stephen, > > > On 15 Oct 2014, at 02:14, Stephen Paul King wrote: > > Hi, > > I re-read S. Mitra's paper <http://arxiv.org/pdf/0902.3825v2.pdf> > again and it made more sense than before if I assumed that the reversible > measurement idea is to be taken as a local reversal to the "direction of > entropy flow" in an area and not the entire universe. > The trouble is this notion of locality. Are there any favorite > definitions of "locality" out there? AFAIK, it does not have a fixed size > in space, but may have a fixed size in "space-time" as location information > expands at the speed of light if we ignore the effects of local structure > that would modulate decoherence. This "decoherence" thing, IMHO, needs to > be looked at carefully. > In deference to Bruno, I should ask a question relevant to the ongoing > discussions. Is a finite universe with locally reversible time consistent > as a 1p world? > > > If the 1p world are described by the []p & p move in arithmetic, then it > seems more plausible that they are antisymmetrical, in the finite case, and > non cyclical in the infinite case. This match the usual phenomenology, I > think. Locally, you can't negate the experience, when you have a pain here > and now, you can't negate the immediate memories. Only a bad doctor would > do that. It is like when you look up if you are in Moscow or Washington, in > the WM duplication. Once you see Washington, that knowledge is not > reversible *from* that knowledge pov". At the 3p level, you can reverse > locally by inducing an amnesia, but that will not be part of the 1p > experience. > > Best, > > Bruno > > > > http://iridia.ulb.ac.be/~marchal/ > > > > -- > 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 http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > -- 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 http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
