What is it that I am thinking of?

[A_Feeble_Mind]

I am trying to find information regarding a phenomenon I remember bits and pieces about, but cannot recall enough of the details to do a proper search on Google.

The phenomenon in question involves a test that occurs only when the results are not being recorded. I think it has something to do with light being shown through slits in a material, but I cannot recall. I do remember that the weird part about it was that if the results were recorded, but the computer was set to instantly delete the results before they could be viewed, the phenomenon would occur.

Anyone have a clue as to what I am thinking of?

 

[davidsmith73]

I am trying to find information regarding a phenomenon I remember bits and pieces about, but cannot recall enough of the details to do a proper search on Google.

The phenomenon in question involves a test that occurs only when the results are not being recorded. I think it has something to do with light being shown through slits in a material, but I cannot recall. I do remember that the weird part about it was that if the results were recorded, but the computer was set to instantly delete the results before they could be viewed, the phenomenon would occur.

Anyone have a clue as to what I am thinking of?

It sounds like you're describing something like Youngs double slit experiment to demonstrate particulate and wave characteristics of light. Try entering "Youngs double slit". I don' remember anything about a computer deleting results or anything though.

 

[Elaborate]

Are you refering to interference of light when it shines through two very small, close slits? From my reading of Richard Feynman's QED, when a single detector is put a few feet away from the slits, an interference opattern of birght and dark bands occurs, but when a detector is placed at each slit, the interference dissapears. He also mentioned taht, if the detectors at each slit were not 100% accurate at detecting light, then the interference is there, but at a much smaller leel than without the detectors; the closer those detectors are to 100% the smaller and smalller the interference becomes.

I've never heard of the experiment with computers though.

 

[Ziggurat]

Well, it sounds a little bit like the two-slit electron diffraction problem. If you send an electron at a plate with two slits in it, some will hit the plate and some will pass through the slits. Electrons that pass through the slits will form a diffraction pattern far away from the plate, indicating that the electron wave function actually passes through BOTH slits and interferes with itself (you can prove it's interfering with itself and not other electrons by sending them one at a time). But it's possible to measure which slit the electron passes through using coils of wire around the slit. If you do this measurement, you don't get a diffraction pattern: the electron will go through one slit or the other, not both. It's the interaction of the electron with this macroscopic measurement apparatus that collapses the wave function. But I don't think you're remembering correctly about the computer part - I don't think deleting the answer can recover the superposition of states.

 

[ceptimus]

Sounds like it might be a more humane version of the Schrodinger's cat experiment - using a computer instead of the cat.

 

[A_Feeble_Mind]

Well, it sounds a little bit like the two-slit electron diffraction problem. If you send an electron at a plate with two slits in it, some will hit the plate and some will pass through the slits. Electrons that pass through the slits will form a diffraction pattern far away from the plate, indicating that the electron wave function actually passes through BOTH slits and interferes with itself (you can prove it's interfering with itself and not other electrons by sending them one at a time). But it's possible to measure which slit the electron passes through using coils of wire around the slit. If you do this measurement, you don't get a diffraction pattern: the electron will go through one slit or the other, not both. It's the interaction of the electron with this macroscopic measurement apparatus that collapses the wave function. But I don't think you're remembering correctly about the computer part - I don't think deleting the answer can recover the superposition of states.

Thanks everyone. This sounds familiar. Thanks for explaining it, as I recalled hearing second hand info about it many years ago and was trying to figure out how deleting the readings could possibly affect the results. What you've said makes sense.