> On 1 Aug 2018, at 20:52, Brent Meeker <meeke...@verizon.net> wrote: > > > > On 8/1/2018 4:07 AM, Bruno Marchal wrote: >> >>> On 1 Aug 2018, at 02:11, Brent Meeker <meeke...@verizon.net >>> <mailto:meeke...@verizon.net>> wrote: >>> >>> >>> >>> On 7/31/2018 2:43 PM, agrayson2...@gmail.com >>> <mailto:agrayson2...@gmail.com> wrote: >>>> >>>> >>>> On Tuesday, July 31, 2018 at 7:14:53 PM UTC, Brent wrote: >>>> >>>> >>>> On 7/31/2018 6:43 AM, agrays...@gmail.com <javascript:> wrote: >>>> >>>> >>>> On Tuesday, July 31, 2018 at 6:11:18 AM UTC, Brent wrote: >>>> >>>> >>>> On 7/30/2018 9:21 PM, agrays...@gmail.com <> wrote: >>>> >>>> >>>> On Tuesday, July 31, 2018 at 1:34:58 AM UTC, Brent wrote: >>>> >>>> >>>> On 7/30/2018 4:40 PM, agrays...@gmail.com <> wrote: >>>> >>>> >>>> On Monday, July 30, 2018 at 7:50:47 PM UTC, Brent wrote: >>>> >>>> >>>> On 7/30/2018 8:02 AM, Bruno Marchal wrote: >>>> and claims the system being measured is physically in all eigenstates >>>> simultaneously before measurement. >>>> >>>> >>>> Nobody claims that this is true. But most of us would I think agree that >>>> this is what happens if you describe the couple “observer particle” by QM, >>>> i.e by the quantum wave. It is a consequence of elementary quantum >>>> mechanics (unless of course you add the unintelligible collapse of the >>>> wave, which for me just means that QM is >>>> false). >>>> >>>> This talk of "being in eigenstates" is confused. An eigenstate is >>>> relative to some operator. The system can be in an eigenstate of an >>>> operator. Ideal measurements are projection operators that leave the >>>> system in an eigenstate of that operator. But ideal measurements are rare >>>> in QM. All the measurements you're discussing in Young's slit examples >>>> are destructive measurements. You can consider, as a mathematical >>>> convenience, using a complete set of commuting operators to define a set >>>> of eigenstates that will provide a basis...but remember that it's just >>>> mathematics, a certain choice of basis. >>>> The system is always in just one state and the mathematics says >>>> there is some operator for which that is the eigenstate. But in general >>>> we don't know what that operator is and we have no way of physically >>>> implementing it. >>>> >>>> Brent >>>> >>>> I can only speak for myself, but when I write that a system in a >>>> superposition of states is in all component states simultaneously, I am >>>> assuming the existence of an operator with eigenstates that form a >>>> complete set and basis, that the wf is written as a sum using this basis, >>>> and that this representation corresponds to the state of the system before >>>> measurement. >>>> >>>> In general you need a set of operators to have the eigenstates form a >>>> complete basis...but OK. >>>> >>>> I am also assuming that the interpretation of a quantum superposition is >>>> that before measurement, the system is in all eigenstates simultaneously, >>>> one of which represents the system after measurement. I do allow for >>>> situations where we write a superposition as a sum of eigenstates even if >>>> we don't know what the operator is, >>>> such as the Up + Dn state of a spin particle. In the case of the cat, >>>> using the hypothesis of superposition I argue against, we have two >>>> eigenstates, which if "occupied" by the system simultaneously, implies the >>>> cat is alive and dead simultaneously. AG >>>> >>>> Yes, you can write down the math for that. But to realize that physically >>>> would require that the cat be perfectly isolated and not even radiate IR >>>> photons (c.f. C60 Bucky ball experiment). So it is in fact impossible to >>>> realize (which is why Schroedinger considered if absurd). >>>> >>>> CMIIAW, but as I have argued, in decoherence theory it is assumed the cat >>>> is initially isolated and decoheres in a fraction of a nano second. So, >>>> IMO, the problem with the interpretation of superposition remains. >>>> >>>> Why is that problematic? You must realize that the cat dying takes at >>>> least several seconds, very long compared to decoherence times. So the >>>> cat is always in a classical state between |alive> and |dead>. These are >>>> never in superposition. >>>> >>>> >>>> When you start your analysis /experiment using decoherence theory, don't >>>> you assume the cat is isolated from the environment? It must be if you say >>>> it later decoheres (even if later is only a nano second). Why is this not >>>> a problem if, as you say, it is impossible to isolate the cat? AG >>>> >>>> That it is impossible to isolate the cat is the source of the >>>> absurdity...not that it exists in a superposition later. >>>> >>>> But if you claim the cat decoheres in some exceedingly short time based on >>>> decoherence theory and the wf you write, taking into account the >>>> apparatus, observer, and remaining environment, mustn't the cat be >>>> initially isolated for this to make sense? AG >>> >>> It never made sense. That it didn't make sense was Schroedinger's point, >>> he just didn't correctly identify where it first failed to make sense, i.e. >>> in the idea that a cat could be isolated. Since the cat can't be isolated >>> then } >>> |alive> and |dead> can only appear in a mixture, not in a coherent >>> superposition. >> >> But a mixture is only a relative notion. It is the superposition as seen >> from inside each superposition. In the universal wave, no mixture ever >> appear (with Everett theory). > > And it doesn't bother you at all that our observations are all of mixtures
That is explained by the (boolean) machine theory, or arithmetic. > and never of superpositions; We observe superposition indirectly all the time. That is why we discover/postulate QM to begin with. When I observe/infer/prepare the state u-d with an u-d/u+d apparatus, I observe/infer/prepare a superposition. > because you are submerged in platonic mysticism. ? Bruno > > Brent > > -- > 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 > <mailto:everything-list+unsubscr...@googlegroups.com>. > To post to this group, send email to everything-list@googlegroups.com > <mailto:everything-list@googlegroups.com>. > Visit this group at https://groups.google.com/group/everything-list > <https://groups.google.com/group/everything-list>. > For more options, visit https://groups.google.com/d/optout > <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.
