On Wednesday, August 22, 2018 at 5:03:16 PM UTC, agrays...@gmail.com wrote: > > > > On Wednesday, August 22, 2018 at 2:19:43 PM UTC, Jason wrote: >> >> >> >> On Wed, Aug 22, 2018 at 2:06 AM <agrays...@gmail.com> wrote: >> >>> >>> >>> On Tuesday, August 21, 2018 at 10:30:01 PM UTC, Jason wrote: >>>> >>>> >>>> >>>> On Tue, Aug 21, 2018 at 4:40 PM <agrays...@gmail.com> wrote: >>>> >>>>> >>>>> >>>>> On Tuesday, August 21, 2018 at 8:02:52 PM UTC, Jason wrote: >>>>>> >>>>>> >>>>>> >>>>>> On Tue, Aug 21, 2018 at 2:20 PM <agrays...@gmail.com> wrote: >>>>>> >>>>>>> >>>>>>> >>>>>>> On Tuesday, August 21, 2018 at 3:04:45 PM UTC, Jason wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Wed, Aug 15, 2018 at 1:44 PM <agrays...@gmail.com> wrote: >>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Wednesday, August 15, 2018 at 2:41:12 PM UTC, Jason wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Wednesday, August 15, 2018, <agrays...@gmail.com> wrote: >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On Wednesday, August 15, 2018 at 11:49:04 AM UTC, Bruno Marchal >>>>>>>>>>> wrote: >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> On 15 Aug 2018, at 12:36, agrays...@gmail.com wrote: >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> On Wednesday, August 15, 2018 at 10:22:40 AM UTC, agrays...@ >>>>>>>>>>>> gmail.com wrote: >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> On Wednesday, August 15, 2018 at 9:58:57 AM UTC, Bruno Marchal >>>>>>>>>>>>> wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> > On 14 Aug 2018, at 22:12, Brent Meeker <meek...@verizon.net> >>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > On 8/14/2018 3:54 AM, Bruno Marchal wrote: >>>>>>>>>>>>>> >> How do you explain interference fringes in the two slits? >>>>>>>>>>>>>> How do you explain the different behaviour of u+d and a mixture >>>>>>>>>>>>>> of u and d. >>>>>>>>>>>>>> >> >>>>>>>>>>>>>> >> If the wave is not real, how doe it interfere even when we >>>>>>>>>>>>>> are not there? >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > How does it interfere with itself unless it goes through >>>>>>>>>>>>>> both slits in the same world...thus being non-local. >>>>>>>>>>>>>> >>>>>>>>>>>>>> The wave is a trans-world notion. You should better see it as >>>>>>>>>>>>>> a wave of histories/worlds, than a wave in one world. I don’t >>>>>>>>>>>>>> think “one >>>>>>>>>>>>>> world” is well defined enough to make sense in both Everett and >>>>>>>>>>>>>> Mechanism. >>>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> *If you start with the error tGhat all possible results of a >>>>>>>>>>>>> measurement must be realized, you can't avoid many worlds. Then, >>>>>>>>>>>>> if you >>>>>>>>>>>>> fall in love with the implications of this error, you are firmly >>>>>>>>>>>>> in woo-woo >>>>>>>>>>>>> land with the prime directive of bringing as many as possible >>>>>>>>>>>>> into this >>>>>>>>>>>>> illusion / delusion. This is where we're at IMO. AG * >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> *Truthfully, I don't know why, when you do a slit experiment >>>>>>>>>>>> one particle at a time, the result is quantum interference. It >>>>>>>>>>>> might be >>>>>>>>>>>> because particles move as waves and each particle goes through >>>>>>>>>>>> both slits. >>>>>>>>>>>> In any event, I don't see the MWI is a solution to this problem. >>>>>>>>>>>> It just >>>>>>>>>>>> takes us down a deeper rabbit hole. AG* >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Everything is in the formalism, as well exemplified by the two >>>>>>>>>>>> slits. If you miss this, then consider the quantum algorithm by >>>>>>>>>>>> Shor. >>>>>>>>>>>> There, a “particle” is not just going through two slits, but >>>>>>>>>>>> participate in >>>>>>>>>>>> parallel, yet different computations, and we get an indirect >>>>>>>>>>>> evidence by >>>>>>>>>>>> the information we can extract from a quantum Fourier transform on >>>>>>>>>>>> all >>>>>>>>>>>> results obtained in the parallel branches. >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> *No. It's all nonsense. AG * >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>> No it's something you can already buy and use today: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> https://techcrunch.com/2017/11/10/ibm-passes-major-milestone-with-20-and-50-qubit-quantum-computers-as-a-service/ >>>>>>>>>> >>>>>>>>>> Jason >>>>>>>>>> >>>>>>>>> >>>>>>>>> *If you're referring to my critique of the standard quantum >>>>>>>>> interpretation of the superposition of states -- that a system in a >>>>>>>>> superposition is in ALL component states SIMULTANEOUSLY -- show me >>>>>>>>> where >>>>>>>>> that INTERPRETATION is used in quantum computers.* >>>>>>>>> >>>>>>>> >>>>>>>> It's in the definition of a qubit: >>>>>>>> https://en.wikipedia.org/wiki/Qubit >>>>>>>> >>>>>>> >>>>>>> *But that's not nearly enough. You have to show where the assumption >>>>>>> is applied. In the case of standard QM, the superposition is written as >>>>>>> a >>>>>>> sum of eigenstates, which are mutually orthogonal. So, as I pointed out >>>>>>> exhaustively with no takers, the assumption isn't used in calculating >>>>>>> probabilities. When you take the inner product of an eigenstate with >>>>>>> the >>>>>>> wf, all terms drop out except the eigenvalue whose probability you are >>>>>>> calculating. Is the situation different with qubits*? AG >>>>>>> >>>>>> >>>>>> >>>>>> These superposed states either exist or they don't. Which is it in >>>>>> your view? In my view they exist, because that is the only way to >>>>>> explain >>>>>> the computational power of a quantum computer. >>>>>> >>>>> >>>>> *I am not doubting the existence of the superposed states; just their >>>>> *interpretation* which is key to achieving the postulated speeds of >>>>> quantum >>>>> computers. See comment below. AG * >>>>> >>>>>> >>>>>> >>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>> >>>>>>>>> * I know it isn't used to calculate probabilities in quantum >>>>>>>>> theory. It's a postulate which is NOT used, so by Occam Razor it >>>>>>>>> should be >>>>>>>>> eliminated. AG* >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> You can't calculate the final probabilities without assuming the >>>>>>>> qubits enter the superposition of all possible states, >>>>>>>> >>>>>>> >>>>>>> *See above. I am not questioning the existence and utility of the >>>>>>> superposition itself, but the assumption that a system in a >>>>>>> superposition >>>>>>> is simultaneously in all component states of the superposition. AG* >>>>>>> >>>>>>> >>>>>> >>>>>> If I start a 200 qubit quantum computer at time = 0, and 100 >>>>>> microseconds later it has produced a result that required going through >>>>>> 2^200 = 1.6 x 10^60 = states (more states than is possible for 200 >>>>>> things >>>>>> to go through in 100 microseconds even if they changed their state every >>>>>> Plank time (5.39121 x 10^-44 seconds), then physically speaking it * >>>>>> *must** have been simultaneous. I don't see any other way to >>>>>> explain this result. How can 200 things explore 10^60 states in 10^-4 >>>>>> seconds, when a Plank time is 5.39 x 10^-44 seconds? >>>>>> >>>>> >>>>> >>>>> *Impressive calculation to be sure, but is this a theoretical value >>>>> based on the assumption I deny; or is it achieved by a working quantum >>>>> computer? AG * >>>>> >>>>>> >>>>>> >>>> >>>> There are working quantum computers with 72 qubits (I had to update >>>> this from 50 after doing some searching). >>>> >>>> Nothing in the theory implies larger quantum computers can't be built, >>>> it is only a problem of engineering. See this graph of recent progress: >>>> >>>> https://www.ibm.com/blogs/research/wp-content/uploads/2018/04/Quantum_Volume_benchmark.png >>>> >>>> Will you change your mind when a 200 qubit quantum computer is built? >>>> From the trend of the graph it looks like we could get there by next year. >>>> >>>> >>>> >>>>> >>>>>> >>>>>>> which is why it becomes exponentially hard to predict what happens >>>>>>>> with a larger number of qubits in a quantum computer. This is why >>>>>>>> large >>>>>>>> scale quantum computers must be built, we can't just simulate them >>>>>>>> with >>>>>>>> regular computers because the number of states it is simultaneously in >>>>>>>> quickly becomes enourmous: >>>>>>>> >>>>>>>> 1 qubit: 2 states >>>>>>>> 5 qubits: 32 states (you can use this quantum computer for free on >>>>>>>> the link I provided) >>>>>>>> 10 qubits: 1024 states >>>>>>>> 20 qubits: 1,048,576 states (you can pay to use this quantum >>>>>>>> computer today >>>>>>>> >>>>>>> >>>>>>> >>>>>>>> ) >>>>>>>> 30 qubits: 1,073,741,824 states >>>>>>>> 50 qubits: 1,125,899,906,842,624 states (IBM recently built a >>>>>>>> quantum computer with 50 qubits >>>>>>>> <https://www.technologyreview.com/s/609451/ibm-raises-the-bar-with-a-50-qubit-quantum-computer/> >>>>>>>> ) >>>>>>>> 100 qubits: 1,267,650,600,228,229,401,496,703,205,376 states >>>>>>>> 200 qubits: >>>>>>>> 1,606,938,044,258,990,275,541,962,092,341,162,602,522,202,993,782,792,835,301,376 >>>>>>>> >>>>>>>> states >>>>>>>> 1000 >>>>>>>> qubits: >>>>>>>> 10,715,086,071,862,673,209,484,250,490,600,018,105,614,048,117,055,336,074,437,503,883,703,510,511,249,361,224,931,983,788,156,958,581,275,946,729,175,531,468,251,871,452,856,923,140,435,984,577,574,698,574,803,934,567,774,824,230,985,421,074,605,062,371,141,877,954,182,153,046,474,983,581,941,267,398,767,559,165,543,946,077,062,914,571,196,477,686,542,167,660,429,831,652,624,386,837,205,668,069,376 >>>>>>>> >>>>>>>> states >>>>>>>> >>>>>>>> We know of nothing in principal that can accurately simulate the >>>>>>>> behavior of a system of 1000 entangled atoms in a reasonable period of >>>>>>>> time >>>>>>>> besides a quantum computer. The reason is the number above (2^1000) >>>>>>>> is so >>>>>>>> large that ant attempt to simulate it will fail due to physical limits >>>>>>>> of >>>>>>>> time, energy, and space within this universe. So if the computational >>>>>>>> capacity of this universe is insufficient to compute what this system >>>>>>>> of >>>>>>>> 1000 qubits will do, what in physics is known which has the >>>>>>>> sufficiently >>>>>>>> large state and computational capacity to perform such a calculation? >>>>>>>> >>>>>>>> Answer: the wave function >>>>>>>> >>>>>>>> At the current time, there is no other known answer nor any hint of >>>>>>>> another theory that can explain the power of quantum computers. The >>>>>>>> only >>>>>>>> answer we have is that the wave function is something that is >>>>>>>> physically >>>>>>>> real. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>> >>>>>>>>> *WRT the MWI, it's too tortured and extravagant to be in the >>>>>>>>> ballpark of reality. AG* >>>>>>>>> >>>>>>>> >>>>>>>> Do you have an alternate theory for how quantum computers can be in >>>>>>>> so many states simultaneously? >>>>>>>> >>>>>>> >>>>>>> *I am not convinced of the simultaneous claim. Where is it actually >>>>>>> applied? It isn't in standard QM. AG* >>>>>>> >>>>>>>> >>>>>>>> >>>>>> I don't know that there is any definition of "standard QM". >>>>>> >>>>> >>>>> *I just meant the Copenhagen postulates of QM. Earlier I reproduced >>>>> Dirac's comment (from Wiki, "Superposition of States") concerning the >>>>> usual >>>>> interpretation of a superposed state, which I don't think is formally a >>>>> postulate. Also, Schroedinger's thought experiment was specifically >>>>> designed to deny it. A*G >>>>> >>>>> >>>> >>>> The postulate is #5 in this list: >>>> http://vergil.chemistry.gatech.edu/notes/quantrev/node20.html >>>> >>> >>> *It is NOT! Maybe English isn't your native language. You don't seem to >>> have the vaguest idea concerning the content of my last comment.* >>> >> >> Try not to be insulting on this list. We're both hear to learn, aren't we? >> >> You might think it is unrelated, but it is not. As the SWE evolves in >> time, superpositions naturally arise. >> >> >>> >>> * The evolution of the wf via the SWE is UNRELATED to my claim about >>> superposition! And it is NOT one of the stated postulates of QM! AG * >>> >>>> >>>> >> What postulates are you using? This list of postulates also contains >> that same one: http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/qm.html >> >> >>> "The wavefunction or state function of a system evolves in time >>>> according to the time-dependent Schrödinger equation" >>>> >>>> >>>> Copenhagen says the superposition remains so long as the system remains >>>> isolated (but is less than clear on what it needs to be isolated from: >>>> e.g. Wigner's >>>> friend <https://en.wikipedia.org/wiki/Wigner%27s_friend>). Therefore >>>> it adds an addendum to postulate 5, namely that the system only evolves >>>> according to the Schrödinger equation while it is isolated, and when it is >>>> not isolated (i.e. being observed), that it does not evolve in time >>>> according to the Schrödinger equation. >>>> >>>> >>>> Schrödinger's cat experiment was initially meant to show QM was >>>> incomplete. >>>> >>> >>> >>> *Not just that, but that there was a problem with the INTERPRETATION of >>> superposition of states, which leads directly to a cat being alive and dead >>> simultaneously. AG* >>> >> >> Yes, so you see, even at that time, they knew simple experiments, like >> listening for a click of a Geiger counter led to superpositions of states >> in the wave function. >> >> And yes, it did imply that the result would lead to a cat being alive and >> dead simultaneously in the wave function (though not in any one branch). >> The problem was they had a mental block, perhaps not unlike your own, which >> made them refuse to consider the idea that reality matched the equations >> they developed and that the superposition was real and there were multiple >> branches containing all possibilities. >> >> It wasn't until 1957 that Hugh followed his teacher's (Wheeler) advice, >> to see what the theory predicts of our experience, and compare it to what >> we actually see. It was in doing this that Everett showed no one >> experimenter would see a live and dead cat, because that experimenter >> himself becomes part of the superposition of the cat, and so only one >> outcome is observed by each instance of the experimenter despite that all >> outcomes occur in the wave function. >> >> >>> >>> >>>> It was only later in his life that Schrödinger realized his equation, >>>> if true (and always obeyed), led to many worlds >>>> >>> >>> *Maybe the SWE is not always obeyed; only prior to a measurement.* >>> >> >> This requires some magic properties of observers to collapse the wave >> function. It requires that quantum computers be unable to execute some >> programs (conscious ones), and it also leads to new problems like how do >> you explain Wigner's friend, and what separates a measurement device from a >> conscious observer? In short, this idea doesn't really work, and worse, it >> is unnecessary: Our observations are consistent with the idea that the SWE >> is always obeyed. So there is no reason to modify the theory. >> >> >>> >>> * Moreover, if the wf is epistemic only, it can change instantaneously >>> as in the example Bruce gave of a horse race (not really a quantum system >>> but illustrative anyway); the probabilities change as the race ensues, but >>> when it ends and the winner is known, the probabilities change >>> instantaneously a the finish line. Maybe this is the case with qubits; they >>> toggle instantaneously between the two possible states, but are never in >>> both states simultaneously. IOW, your model of how quantum computers >>> function might be totally wrong in a conceptual sense, but is useful in >>> their construction. AG* >>> >>>> >>>> >>>> >> You are suggesting that two things can happen in the same time with the >> same qubit. How is that not the very definition of simultaneous? >> > *OK. Sorry. I conflated two proposals which confused the issue; (1), that the quibit toggles between two states and is NEVER in both simultaneously, or (2), the wf can change instantaneously between the two states if it's epistemic only (illustrated by Bruce's horse race model), in which case I concede it could be conceived or imagined as being in both states simultaneously. But in the latter case, the wf wouldn't be physical, and your model of quantum computers might need to be revised, consistent with my DELETION OF THE EXTRANEOUS UNSTATED POSTULATE of QM concerning the physical meaning of a superposition (don't make me state it for the nth time). I find the idea of both qubit states being simultaneously occupied as implausible because this assumption is not used in calculating probabilities in QM (because the eigenstates in the superposed expansion are orthogonal). AG*
> >> Jason >> > > *English is not Bruno's native tongue. Perhaps it's not yours. AG* > -- 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.
