Hal Finney wrote:
[EMAIL PROTECTED]">Future uncertainty is familiar to us, but one of the things that the many universe model introduces is past uncertainty. There is a sense in which the past is not unique and determined. My mental state is consistent with many macroscopically distinct pasts.
I agree with Hal that we have many pasts. Past indetermincy can have at least three causes:
1) Macroscopic effects as Hal suggested. The same macroscopic mental states can be the result of several pasts.This idea is related to Leibniz's principle of indistinguishable (or indiscernable). If two things are so similar as to be indistinguishable then they are the same. If several universes appear identical as seen from a your given mental state then you actually live in all these universes.
2) Deterministic Indeterminacy (the butterfly effect according to which infinitesimally small causes can generate large effects) This phenomenon can operate in the forward time direction as well as in the reverse time direction. Small present mental state differences can be the result of large differences in the past. This can lead to quasi-identical mental states with largely different pasts.
3) Quantum Phenomenons. Consider an experiment in which you attempt to define the past by performing a measurement on a recording device such as a video recorder, a computer memory or even your own neuronal memory. The experiment itself is subject to quantum indeterminacy, and therefore your ability to know the past remains forever fuzzy. ERGO, several pasts are possible. Of course you can refine your experiment and get more and more precise in your determination of which universe you actually live in. Each experiment will generate a fork in the multiverse, some of you(s) will discover that they have some given pasts, and others of you(s) will discover that they have other pasts. The point however, is that you will never reach complete certainty.
Tim May wrote
Nothing in science points to the "many actual pasts" possibility, even though I acknowlege your point that "many _possible_ pasts" would lead to a indistinguishable equal mental state for you or me.
hmmm, interesting idea but I would not dismiss it so quickly. I also came to the same conclusion. I believe there exist a continuous "locus" of consciousness which consists of all the conscious states and which includes, among many others, you, me, cats, dogs, and ET's. This locus is continuous in the sense that it morphes from you to me and vice versa in small infinitesimal steps. In facts it also morphes from me today to me tomorrow, and from you today to you tomorrow.