On Sat, Jun 10, 2017 at 1:11 AM, Bruce Kellett <bhkell...@optusnet.com.au> wrote: > On 10/06/2017 2:36 am, Telmo Menezes wrote: >> >> On Fri, Jun 9, 2017 at 12:37 AM, Bruce Kellett >> >>> The idea that the explanation is epistemological rather that ontological >>> has >>> been my preferred position for a long time. If the wave-function is >>> merely >>> an epistemological device for calculating probabilities and not a really >>> existing object, all worries about collapse and action-at-a-distance >>> vanish. >>> Of course, multi worlds also vanish, but in my opinion that is no bad >>> thing. >> >> So what's your position on Deutsch's argument about quantum computers? >> Where does the extra computing power come from? > > > It has long been understood that Deutsch is out to lunch on this. > > He appears > to assume that a quantum computer is just using the same algorithms that a > classical computer would use, only executing them in a massively parallel > manner.
I find it very hard to believe that David Deutsch does not have a good understanding of quantum computers. > This is manifestly false. Quantum computers operate in a completely > different way -- that is why there are so few actual algorithms for quantum > computers to execute that gain massive speed improvements. I think you built a straw man and now you're attacking it. When I heard Deutsch make the argument, he was referring explicitly to Shor's algorithm. This is sufficient to demonstrate an increase in computational power that would be impossible in the classical world. As for more general speed improvements, there is for example Grover's algorithm, that offers a quadratic improvement in searching unsorted lists. This has wide applicability in software engineering. Of course, building more complex quantum computers is still beyond our technical abilities. I don't think that's news for anyone... > As Brent says in his recent post, Scott Aaronson points out: > "The way a quantum algorithms work is that they arrange for wrong answers to > destructively interfere while the desired answer interferes constructively. > Interference requires that they take place in the same world." Yes, but this is not classical interference, it's interference between superpositions of states. So how can this computation happen in the physical world? For me, that gives more credence to the claim that the wave function describes a real object. > Classical computers do not have quantum interference. Quantum computing does > not prove the existence of parallel worlds -- there is no need for other > worlds in which to find the computational power, you just need a modicum of > insight into how quantum computing algorithms work. > > You might claim that Deutsch is a known expert on quantum computing, but > more commonly, Deutsch is known for having way out, non-standard ideas on > quantum mechanics. Oh no! Everyone should be kept in line! Telmo. > > Bruce > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to everything-list+unsubscr...@googlegroups.com. > To post to this group, send email to everything-list@googlegroups.com. > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
