There have been a number of attempts to derive/justify the Born rule, including the self-locating uncertainty approach that Carroll and Sebens develop (I haven't looked at their paper, but they probably cite earlier works in the same vein). Not everyone is convinced that such justifications are (a) not circular, and (b) do not smuggle in assumptions that are not present in the starting interpretation. But adjudicating this debate is way beyond my pay grade. — SophistiCat
I just want to take issue with your characterization of probabilistic theories as "acausal." What you are talking about is causal determinism, and the keyword here is determinism. You can, of course, put your foot down and insist that causality necessarily implies determinism, but, as far as your arguments here are concerned, causality may as well equal determinism, because you are not actually talking about any aspect of causality other than it being deterministic. So for your purposes, causality is a redundant concept, since all that you are talking about is determinism. And I suspect that you only bring it up for rhetorical purposes (everyone wants to preserve causality in our theories, right?) — SophistiCat
Reading through the reader reviews of that title, it seems Deutsch gives pretty short shrift to anyone who doubts the actual reality of parallel universes, which he seems to think is necessary for the concept to actually work. — Wayfarer
Logically, the possibility of complex quantum computations adds nothing to a case that is already unanswerable. But it does add psychological impact. With Shor’s algorithm, the argument has been writ very large. To those who still cling to a single-universe world-view, I issue this challenge: explain how Shor’s algorithm works. I do not merely mean predict that it will work, which is merely a matter of solving a few uncontroversial equations. I mean provide an explanation. When Shor’s algorithm has factorized a number, using 10^500 or so times the computational resources that can be seen to be present, where was the number factorized? There are only about 10^80 atoms in the entire visible universe, an utterly minuscule number compared with 10^500. So if the visible universe were the extent of physical reality, physical reality would not even remotely contain the resources required to factorize such a large number. Who did factorize it, then? How, and where, was the computation performed? — David Deutsch - “The Fabric of Reality”
↪Andrew M where are numbers? Any numbers? There might be a vast domain of which the physical universe is simply an aspect, but which is not physical. //edit// Where is 'the realm of possibility'? You might say 'it doesn't exist', but then, there are some things which are in the domain of possibility, and some things which are not. So there are 'real possibilities' - but they don't actually exist anywhere. Which, in the context, is significant, I would have thought.// — Wayfarer
//edit// Where is 'the realm of possibility'? You might say 'it doesn't exist', but then, there are some things which are in the domain of possibility, and some things which are not. So there are 'real possibilities' - but they don't actually exist anywhere. Which, in the context, is significant, I would have thought.// — Wayfarer
↪Andrew M in which case, I faill to see the cogency of that example for Deutsch's argument for there being many worlds. — Wayfarer
It would be great if everyone wanted to preserve causality in their theories but that is what the Copenhagen interpretation explicitly rejects. The idea that the universe is inherently probabilistic implies that the probabilities are a brute fact and inexplicable. — Andrew M
* That may not actually be true - some interpretations seem to make distinct predictions, but they are presently out of reach for empirical investigation. — SophistiCat
What you are really saying is that our theories ought to be deterministic. — SophistiCat
the Everett interpretation does seem to be more parsimonious than — SophistiCat
In response to previous assertions that the reality of multiple universe is 'craziness' is it any more crazy than any of the other interpretations?! (Cat both dead/alive etc) — Mike Adams
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