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.

>   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?

Particle *probabilities* are in superpositions. That doesn't make them waves.

But again, this is a question of "why does it work that way", and not "how 
does it work", and AFAIK nobody knows the underlying reason why the 
probabilities work out the way they do.

>> 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. :-)

>> Again, it's not a question of one photon making an interference pattern. 
>> It's a bunch of photons making an interference pattern. Any one photon shows 
>> up all at once and makes a single discrete mark wherever it hits. It's just 
>> more likely to hit in one area than another.
> 
>   Of course I implied that you perform the test many times and see the overall
> pattern that the photons create.

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

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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