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 <javascript:>> 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. 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 * > > "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 * > 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. 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* > > > Jason > -- 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.
