# Why is the camera not the culprit? [duplicate]

Perhaps I am completely wrong, but as I understand it our observation of a system can affect the outcome. The example I remember is the double slit experiment where electrons behave as a wave at first, but when observing it behaves as a particle. The conclusion, as I remember hearing, is that observing the system is what caused the different outcomes.

Why is this that case? Couldn't it have been the camera (or whatever is used to detect/observe/etc.) that causes the difference? It just seems like there are a few potential explanations that get skipped over here.

Excuse me while I most likely butcher this experiment with an example. Say I turn on the sink and water goes from the faucet to the drain. Now when I hold a cup under the water, it no longer hits the drain, instead it is captured in the cup. My explanation, having my hand there causes the behavior.

This has bugged me since I first heard it, and I have yet to find an explanation that I can accept. Given, that may be due to my inability to comprehend some of the more complex explanations, but I would still like to figure it out.

## marked as duplicate by DumpsterDoofus, Kyle Kanos, Brandon Enright, John Rennie, BebopButUnsteadyMar 19 '14 at 19:12

• Are you asking if an intelligent observer is required to collapse the wavefunction or whether a purely mechanical observer (like a camera) is sufficient? – The Photon Mar 18 '14 at 20:48
• I'm asking why the conclusion is the act of observing, and not the device. For example, perhaps the device creates a magnetic field or some sort of interference that causes the different result. It would be like me saying 1+1 written in pencil makes 2 while 1+1+1 in written pen makes 3 because it is written in pen. – David Starkey Mar 18 '14 at 20:59
• I assume you're talking about Young's double-slit experiment or any other optical diffraction experiment. If we use a film camera, or a CCD, or move a photodiode around, or just look at the light shone on a piece of paper in a dark room, we see the same pattern. Is there experimental evidence that a different mechanism for measuring the diffraction pattern gives a different result? – The Photon Mar 18 '14 at 21:04
• @ThePhoton If I look at light going through 2 slits in a dark room, I should see it behaving as a wave, correct? So if I introduce equipment and that changes the behavior, it should be the equipment, not the act of observing, right? – David Starkey Mar 18 '14 at 21:09
• If you shine coherent light through two appropriately-sized slits onto a screen, you will see a diffraction pattern. If you take a film or digital photo of the pattern, it won't change the pattern. If you replace the screen with a big piece of film, it will record the same pattern. – The Photon Mar 18 '14 at 21:12