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Double slit and psychology? General question.

  1. Sep 16, 2012 #1
    Hi guys,

    Please excuse me, I do not know a great deal about Quantum physics.

    First, tell me if I am correct. If we shoot electrons at a double slit plate, and we do not watch or "observe" it, it will show a pattern similar to a wave pattern. But, if we record it, or observe it, it will just show a pattern similar to the 2 slits. ?

    Is there any part of our brains electrical activity that affects the double slit experiment? Or is just purely the act of any type of observation?

    Does it have anything at all to do with us specifically?
  2. jcsd
  3. Sep 16, 2012 #2
    It doesn't actually have anything to do with us. It happens even if nobody directly observes the experiment, if we try to detect which slit the electron goes through in any way. To detect the electron, we have to probe or disturb it in some way. It's this disturbance that causes the electron to change its behavior.
  4. Sep 16, 2012 #3
    What force is making them change behaviour when something is recording/measuring them?
  5. Sep 18, 2012 #4
    Hey nukeman, it's simply the electrical force of the electron/light you use to detect the electron, you change it's path, you change it's wavelength, so it's wavelength collapses...... if the electron is present in the location in witch you tried to detect it. But no you can not think and affect the quantum world..... or probably not, unless the electrical/magnetic fields of thoughts in the brain are strong enough, but it's not really noticable.
  6. Sep 18, 2012 #5
    Physics is the science of the world around us it has nothing to do with psycology and no the observing in double slit experiment is not the same as what we mean in general it has nothing to do with our brain. One more think don't listen to those people from that secret film where they taliking about the Law of attraction and stuff.
  7. Sep 19, 2012 #6
    This idea that consciousness affects what the electron does is a view of physics that was in vogue one hundred years ago but IMO became obsolete 60 years ago. I guess it may never go away. People like it.

    The way I see it, there is no requirement that an "observer" be conscious. In fact, we don't really observe those electrons at all. Machines observe the electrons. We just look at graphs and tables and such.
  8. Sep 19, 2012 #7


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    Rather than thinking about 'observing' electrons, consider what would happen if one of the slits is of a different width to the other. The resulting pattern will be a combination of the fringes due to two slits and a, more or less, single peaked distribution of the wider slit. This is because the narrower slit has obstructed the possible path for some of the electrons which have managed to get through the wider one. Those electrons have been 'observed' - or singled out - by the narrow slit and can no longer take part in the interference process. The same thing could happen if you were able to 'swat' some of the electrons going through one of the slits (say, with a beam of protons going across the slit). In this case, some of the electrons would have interacted with a proton. Their presence at that slit would have been identified (by colliding with a proton and even producing a flash of light) and so they would have zero probability of going through the other slit and so could not interfere with themselves and contribute to any interference pattern.
    There were a bunch of experiments a few decades ago in which people sat staring at screens and trying to 'cause' effects or to 'predict' things. I don't think they got anywhere.
  9. Sep 19, 2012 #8
    I think observation is an outdated word, in the context it should be interfere or disturb a wave... the thing that the word observe implies is simply not fitting.
  10. Sep 19, 2012 #9
    to observe something you have to interact with it

    for macroscopic things, just looking at something and seeing it with our eyes has no noticeable effect on its behaviors

    but to "look at" an electron, you need to bounce photons off of it, or something like that. It needs to interact with something in order to be observed and detected. Since electrons are so small, when you bounce a photon off of one, its behavior is affected in a noticeable way.
  11. Sep 19, 2012 #10


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    I see what you're getting at but I think the point is to realise that, observing it means that its path (/ wave function) is committed and the electron cannot be at the other slit. If anything interacts with it on its journey, it can no longer be involved in the 'probability game' that produces a diffraction pattern of both slits. In principle, any interaction would leave a record of its occurrence which could be noticed or 'observed'.
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