On Monday, January 13, 2003, at 12:38 PM, George Levy wrote:
On your point about "many pasts are fundamentally caused by quantum uncertainty in memory devices," I strongly disagree. There is only one past for one present, whether RAMs dropped bits in recording them or historians forgot something, etc.
Tim May wrote
If you mean that "many presents" have "many pasts," yes. But the current present only has a limited number of pasts, possibly just one. (The origin of this asymmetry in the lattice of events is related to our being in one present.)
I mean one (many?) present has many pasts as well as many futures. Many pasts are fundamentally caused by quantum uncertainty in memory devices; many presents are caused by uncertainty in observation devices; many futures are caused by uncertainty in the controlling devices. The past cannot be ascertained precisely just as the future cannot be predicted precisely. Our consciousness is a fuzzy point in the many world. It has an infinite number of pasts and an infinite number of futures, an everbranching tree toward the past and an everbranching tree toward the future. Taking many observer moments together, I view the many world more as a lattice then as a tree. Thus navigation in the many-world makes sense.
(This is captured by the formalism of observations, as well. Even with Uncertainty, all honest observers will report the same outcome of an experiment. We have not seen a violation of this, nor is one expected. There are various ways to look at this, including the topos-theoretic view of subobject classifiers. But the point is that in our history either an event happened or it did not. This is independent of whether the event was observed, recorded, written about, remembered, etc.)
But this is a topic of great fascination for me, and I hope we can continue to discuss it. I am quite strongly persuaded that "many pasts for a particular present" is not a reality.
Understand that I am not including "current interpretations," as in "Some historians think the Roman Empire fell because of lead in their plumbing" sorts of theories of the past. I am referring to space-time events.
As noted, I also view time and events as a lattice. But lattices have certain properties of importance here. More on this later.