Discover magazine has just put online an article from April about quantum experiments that some physicists take as confirming the idea that the future influences the past, and it’s a great read.
I was particularly interested in the discussion of what this means for free will, to be found on the second page of the article. I’m not sure that reading this extract will make complete sense without reading what precedes it, but here goes:
The Rochester experiments seem to demonstrate that actions carried out in the future—in the final, postselection step—ripple back in time to influence and amplify the results measured in the earlier, intermediate step. Does this mean that when the intermediate step is carried out, the future is set and the experimenter has no choice but to perform the later, postselection measurement? It seems not. Even in instances where the final step is abandoned, Tollaksen has found, the intermediate weak measurement remains amplified, though now with no future cause to explain its magnitude at all.
I put it to Tollaksen straight: This finding seems to make a mockery of everything we have discussed so far.
Tollaksen is smiling; this is clearly an argument he has been through many times. The result of that single experiment may be the same, he explains, but remember, the power of weak measurements lies in their repetition. No single measurement can ever be taken alone to convey any meaning about the state of reality. Their inherent error is too large. “Your pointer will still read an amplified result, but now you cannot interpret it as having been caused by anything other than noise or a blip in the apparatus,” he says.
…
The error range in single intermediate weak measurements that are not followed up by the required postselection will always be just enough to dismiss the bizarre result as a mistake.
Tollaksen sums up this confounding argument with one of his favorite quotes, from the ancient Jewish sage Rabbi Akiva: “All is foreseen; but freedom of choice is given.” Or as Tollaksen puts it, “I can have my cake and eat it too.” He laughs.
Here, finally, is the answer to Aharonov’s opening question: What does God gain by playing dice with the universe? Why must the quantum world always retain a degree of fuzziness when we try to look at it through the time slice of the present? That loophole is needed so that the future can exert an overall pull on the present, without ever being caught in the act of doing it in any particular instance.
“The future can only affect the present if there is room to write its influence off as a mistake,” Aharonov says.
I can’t think right now if there is a word for it theologically, but doesn’t this sound a lot like the idea that God does indeed influence the world, but only in ways that can never be clearly identified as such? This was what God said at the end of my favourite episode of Futurama. I suppose it’s like saying that the God of the gaps will always have a gap in which He can be concealed; it’s inherent in the nature of the universe.
Atheists will say “what a cop out”, but the quantum world seems so weird, I don’t think they’re really in a position to rule anything out.
The idea of backward causation is also relevant to Tipler’s Omega Point, in that the end state of the universe (essentially, eternal God) determines the beginning and what goes on in between. That Tipler manages to cram the miracles of Jesus into that as a necessary element is the stretch that nearly no one can swallow, but the big picture an eternal superintelligence pulling the universe towards it retains a deep appeal.
UPDATE: There was another recent paper on arXiv about quantum entanglement as a measure free will; but I find it rather hard to follow, even in this explanation of the paper.
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