>Oops, my prejudice is showing. I can hardly believe that time travel
>will be possible because of the paradoxes and contradictions it would
>bring.
My own prejudice is about to show:
I've spent a lot of time reading in parapsychology, good, bad and
indifferent, and have done some experimental work of my own in
precognition. My current best guess is that some claims of psi are valid,
and that the record clearly shows that veridical non-inferential
foreknowledge is possible (although in a vagrant, transient and
irritatingly stochastic fashion).
Most of the rational posters on this list will be horrified by this
declaration, and I don't blame them. Luckily, there are convenient sources
of information about this apparently absurd and New Ageish claim. Right
now I'm reading a quite good generalist 1997 book on the topic by Dean
Radin, PhD, with the unfortunate catch-penny title THE CONSCIOUS UNIVERSE
(Harper Edge). Even more unfortunately, the art dept has a floating - but
unbent - sugar spoon on the cover, despite Radin's explicit decision *not*
to discuss Geller's exploded claims in his book. The great merit of his
treatment is a lucid account of various recent meta-analyses of many
hundreds of parapsychological experiments, which together provide effect
sizes on the order of that demonstrated by aspirin against cardiac disease.
The book's best feature, for me, is a series of charts showing the
concerted data points, their error bars, and the overall non-chance
meta-results and associated very tight error bars.
If this line of thought is correct, we already have ample evidence that
something like informational time travel exists. I suspect it might have
its best explanation in a Deutsch many-universes manifold, in which the psi
percipient obtains data from a sheaf of contiguous `parallel worlds' -
which somehow provides a better-than-chance estimate of how things might
turn out in *this* world, without actually being a one-universe time-loop.
If you see what I mean.
I find this especially interesting as an onlooker at the feast of physics,
because I treat psi as a crucial data point permitting us to sort out
available theories according to where they allow or disallow certain
non-local factors quite contrary to the way favored by most physicists (who
wish to forbid temporal foreknowledge at all costs).
Damien Broderick