The double slit experiment

[Darawan]

Hi! Well I was wondering if you and I would to do the double slit experiment together and I would to measure which path the electron would take through the double slits and never ever tell you the results of what I saw and you did not know that I am measuring. Would you see an interference pattern? I have another question as well, let's say I put the measuring kit next to the slits so they are ready to observe the electron. Well if you did not know anything about it and I would be off to let's say England would there be an interference pattern?

[Klaynos]

Of the measurement is done the interference pattern will not be observed. Whether the observer is aware of the the measurement or not is irrelevant.

[Delbert]

I understand a photon doesn't travel from the source to the destination. I further understand what we call a photon leaving the source immediately dissolves into a probability field, which represents where we might say it might be found. But it seems that the might aspect is a human construct because that in itself perhaps wouldn't answer the paradox of it going through both slits. That presumably can only be answered by concluding that the 'energy' representing the photon is spread out as some sort of wave function and only 'comes together' at the destination.

 

Trying to identify which slit it goes through by whatever method changes the experiment. Such that checking its path at the slits chances the experiment into two experiments. One from the source to a slit, and a second from the slit to the destination. And as such there's no slit mid path for either experiment, and so no interference pattern. But then again the conclusion from the above is: the damn thing doesn't exist anyway!

[Enthalpy]

Few years ago, the answer was simply: observe a photon means destroy it.

 

So if it's observed at one slit, you won't see it later, neither as fringes nor as anything else.

[swansont]

The OP asked about electrons, but in any event, you can do interference and obtain which-path information without doing a detection until after the interference occurs (if it does).

[michel123456]

Few years ago, the answer was simply: observe a photon means destroy it.

 

So if it's observed at one slit, you won't see it later, neither as fringes nor as anything else.

Why 'few years ago"?

[Delbert]

Few years ago, the answer was simply: observe a photon means destroy it.

It seems to me that it wasn't even there in the first place.

 

There was an event at the source and an event at the destination. For some strange reason we call that an object or particle moving from source to destination. That's an assumption; and as we all know, making assumptions is a dangerous activity.

Edited August 12, 2013 by Delbert