[ExI] CQT Researcher Uncovers Quantitative Link Between Quantum Non-Locality and Uncertainty.

[John Clark]

On Dec 5, 2010, at 10:35 AM, Damien Broderick wrote:

> Can you bounce the light off a mirror, or send it through a lens, before running it through the two slits, and still get fringes? I would assume that you can't, because that *would* be a "measurement".

The history of the photon before it hit the mirror is irrelevant. You'd still get fringes UNLESS there was a measurement made AFTER the photon left the mirror to determine if the photon went through slit A or slit B; unless a measurement is made it is meaningless to ask which slit it went through, at least that's what you'd say if you believed in the Copenhagen interpretation.

If you believed in the Many Worlds interpretation you'd say that when the photon approached the slits the universe split, but when they hit the film the 2 universes would recombine because there was no longer any difference between the 2 universes, but you'd still have evidence the photon went through slit A only and evidence it went through slit B only and that would produce fringes; measurement doesn't enter into it as the two universes would recombine even if you replaced the film with a brick wall, if you had neither film nor a brick wall and allowed the photons to go out into infinite space after passing the slits the universe would split and remain split because there would be an enduring difference between the 2 universes. 

Unfortunately there is no way to perform experiments on photons traveling in infinite space, and if  they hit a photographic plate and are destroyed both Copenhagen and Many Worlds predict identical experimental results, that makes figuring out which is correct difficult.

 John K Clark

 
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