On 3 April 2014 16:56, <[email protected]> wrote: > > On Thursday, April 3, 2014 3:07:26 AM UTC+1, Liz R wrote: > >> On 3 April 2014 14:39, <[email protected]> wrote: >> >>> >>> On Thursday, April 3, 2014 1:24:28 AM UTC+1, Liz R wrote: >>>> >>>> gbhibbsa, I'm getting a bit confused here. All I said is that >>>> wavefunction collapse isn't an observed fact, which seems to me a fairly >>>> reasonable statement, because we can't observe entities like wavefunctions >>>> directly, and we certainly can't observe their collapse directly. Some >>>> people would say we can't observe *anything* directly, but under the >>>> normally understood meaning of "observe" it seems reasonable to say that we >>>> observe the images on our retinas, and hence that we can observe the dots >>>> on a screen, and we can also be reasonably said to be able to observe the >>>> pattern they make. I'm not saying anything about the MWI or Copenhagen or >>>> whatever here, merely that (in normal usage of "observe") we can observe >>>> dots on a screen, and we can't observe abstract theoretical entities like >>>> wavefunctions, or their collapse. >>>> >>> >>> I apologize for the extensive subset of my much more extensive range of >>> shortcomings causing up to all of that confusion. >>> >>> May I try again...this time boiling it all down to a single >>> request? Based on what was at the time the widely accepted proxy for >>> the more problematic meaning of 'observation', what was observed that gave >>> rise in the first place to the widely perceived, arguably urgent, need for >>> an Interpretation of what it meant? >>> >> >> The observation described above, and shown in the pictures. The need for >> interpretation comes from the fact that the objects (electrons or photons, >> for example) involved are assumed to be far too small to be influenced by >> both slits in the experiment (the fact that they form localised dots on the >> screen also indicates that they are very small). Yet all these small >> objects manage to build up a global interference pattern involving the >> presence of both slits (a pattern that vanishes if one slit is covered). >> >> This doesn't at first seem paradoxical, because a similar phenomenon >> occurs when a wave in water passes through two gaps of the right size, for >> example. In this case there is a medium present at each point through which >> the waves are travelling, so the influence has something to transmit it, >> and the resulting effect is easily explanied. >> >> So one's first guess is likely to be that the photons or electron in the >> 2-slit experiment are just be interfering with each other in a similar >> manner ... which wouldn't be paradoxical , of course ... except for the >> additional fact that the intensity of the source can be turned down until >> only one particle is passing through the apparatus at any given time - yet >> even in this case, the interference pattern still appears (eventually). >> >> This situation appears in need of "urgent" explanation because the >> apparent smallness of the particles in relation to the size of the >> equipment suggests that a single electron or photon can't possibly "know" >> about (be influenced by) a slit which it doesn't pass through, and which >> is, relatively speaking, a large distance away. Assuming a photon passes >> through the left hand slit, say, there is no known physical mechanism >> available to tell it about the existence of the right hand slit. Yet it >> will hit the screen in a position that is (statistically) determined by >> what looks like interference between waves passing through both slits. >> Hence the paradox. >> > > I'd agree that's a component but why is that on its own a more urgent > problem than the action at a distance problems with Newton's force when > gravity? Or all those contradictions that accumulated in the late 19th > century, that people felt were pretty incomprehensible and shocking, yet no > one at any time started talking about the need for an 'interpretation' that > made it all feel explained at any price? How come everyone was willing to > leave all those problems wide open for up to hundreds of years, until not > just an interpretation and explanation but scientific next generation > theory, complete with all the traits science the way they knew and loved > were explicit and visible. They had worse problems than this electron? On > there own terms, as the knowledge they had, that was important to them, > that was being upended by the contradictions that they faced. Was it worse > for them, or where they just willing to live with it, because they knew > they just had not accumulated enough knowledge yet to begin to answer the > questions? >
I'm not sure who you're arguing with here, if anyone. All I said was that the collapse of the wave function hasn't been directly observed. I guess you've agreed with that comment, if you want to move on to something else. So, after that you moved on to what was the problem with the two slit experiment. OK, so I've explained that, and since you've moved on from that, I must assume you understood and agreed with the explanation. So what are you moving on to now? Why it was considered an urgent problem? You mean as opposed to why everything else in science is considered an urgent problem (phlogiston, planetary orbits, what the stars are, whether the luminiferous aether exists, what happens to Maxwell's equations when you travel at the speed of light, why the perihelion of Mercury advances, how entropy can increase from time-symmetric molecular collisions, whether the universe is expanding, what happens when an object collapses under its own gravity, whether atoms exist...) Well, the short answer is that it wasn't. Scientists worry about all sorts of problems, some have even been burned at the stake for trying to solve them. > > The Interpretation Movement, was pretty unprecedented in that sense. > It wasn't. Read up on the history of science and you will find plenty of people worrying about stuff they couldn't explain. That is largely what drives science, after all. > That an explanation,....a way to make sense of....was raised over > everything else, including whether and what extent that explanation > inherited any of the traits most fundamental, most unique, to science and > science only. MWI hasn't got one. Not one. Or name one, and explain why > it's fundamental to science, and unique to science and only science. > As I understand it, the "QM interpretation movement" stalled for about 30 years before the MWI came along. Everyone more or less agreed to "shut up and calculate" but a lot of people were vaguely dissatisfied with the situation (including Einstein). Also, I suppose one of the "scientific" traits the MWI has (allegedly) is that it takes the equation(s) of QM at face value, rather than postulating extras like the collapse of the wave function - although whether it succeeds or not is a different matter. There seems to be a lot of people who think it doesn't. > There are some parts you didn't mention unless I missed it.....like the > way that pattern goes away when we try to look at see which slit the > electron goes through. And the way the same pattern shows up even if > electrons are fired one at a time. Even if the interval is a year or a > million years. > Yes I mentioned that. Here, to be exact - "which wouldn't be paradoxical , of course ... except for the additional fact that the intensity of the source can be turned down until only one particle is passing through the apparatus at any given time - yet even in this case, the interference pattern still appears (eventually)." -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
