Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> > Darren New <dne### [at] sanrrcom> wrote:
> >>>   But it seems that everybody knows that it does not happen by the photon
> >>> going through both slits?
> > 
> >> Correct.  Or, rather, nobody has ever measured anything that would imply the 
> >> photon goes through both slits as a wave.
> > 
> >   The interference pattern in the detector is not a measurement?

> No. It's a bunch of individual measurements of different photons. There's no 
> way to look at *one* photon and decide whether there was one slit or two. 
> Because it's not a wave, it's a particle, so it always makes the same sort 
> of single-spot quantum event in a single place.

  That's like saying that you can't measure the probability of a coin
giving heads because you can only toss one coin at a time.

  I'd say tossing 100 coins one after another is exactly as valid as if you
had tossed one coin 100 times simultaneously (if that was physically possible).

> >   But I thought that's the whole idea in the Copenhagen interpretation:
> > Particles are in superpositions until they are measured, in which case
> > they collapse into a definite state. Thus when you measure a photon, you
> > will always find a collapsed photon.

> If every time one measures something, one gets "it isn't a wave", then why 
> would one think it's ever a wave?

  Because of the interference pattern?

  If it behaves like a wave, what can we deduce from that?

> >> But it only goes through one slit if you measure which slit it went thru. 
> >> This is true even *if* you make the measurement *after* the slits. You never 
> >> see the photon going through both slits, like you would if it were actually 
> >> a wave.
> > 
> >   You also never see the cat in both live and dead states at the same time.

> That's actually evidence for it being particles and *not* waves. :-)

  It's an argument that measurement doesn't necessarily tell what was the
state before the measurement was performed.

> Yes. But if a photon was a wave, it could interfere with *itself*. It could 
> split up and go through two separate slits. One photon doesn't make an 
> interference pattern, and that's how you know the photon isn't a wave.

  That just doesn't convince me. Just because the photon collapses when it
hits the detector doesn't mean that on the way it didn't pass through both
slits at the same time and interfered with itself.

  It sounds like you are arguing that particles cannot be in superimposed
states and that there's no collapse phenomenon when they are measured, but
instead they are always at single places at a time, in particle form. In
other words, that the Copenhagen interpretation is wrong. (Of course, if
I have understood correctly, nobody has proven that it's right, but you
are seemingly claiming it's wrong. Has that been proven?)

  (Not that I have the slightest idea what I'm talking about. The problem
I'm having is that, seemingly, people have no idea why the interference
pattern appears yet are completely sure it's *not* because photons are
in wave state at any point.)

> You 
> don't see half the photon's energy hit here and half hit there with a blank 
> spot in the middle.

  You don't see it because if you try to see it, the photon collapses and
the only thing you see is a particle.

-- 
                                                          - Warp

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