In most of the explanation clips of the double-slit experiment, nobody talks about possible detector interference.

This is the only clip that I've found to explain that the detector doesn't cause interference with the photons, stating that the wave pattern disappeared only when they were collecting the data, and appeared back if they did not collect the data(detectors still on, but no magnetic tape to write the results to):

Explained ! The Double Slit Experiment

Is this the truth?

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    $\begingroup$ Can you summarize the argument instead of linking to a video? And what do you mean by "detector interference"? You'll have to explain what that means. $\endgroup$
    – garyp
    Jun 7, 2016 at 13:45
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    $\begingroup$ I don't like this ironic comments, that's Thomas Campbell and I'm nobody. You can't just serve me the "your getting the science from Youtube". It's a conference, it's not some random dude posting his own backyard conclusions. $\endgroup$
    – Nick
    Jun 7, 2016 at 14:23
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    $\begingroup$ CuriousOne, let's better focus on this direction, as it's a more constructive one: "Anyway, his description left me perplex also, but what would leave me even more perplex would be the fact that a scientist would consider that he has the same environment conditions when turning the detectors on, as he does when he has them off." $\endgroup$
    – Nick
    Jun 7, 2016 at 14:28
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    $\begingroup$ I think that you should stop, because your comments are not useful to the discussion. I was reasonable, showing you a constructive direction to talk about, since we settled that the statement of the video is false, but you keep on writing ironies. $\endgroup$
    – Nick
    Jun 7, 2016 at 15:36
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    $\begingroup$ @CuriousOne You made your point. Move on. $\endgroup$
    – garyp
    Jun 7, 2016 at 17:55

1 Answer 1


The part of the data collection and its consequences to the result of the experiment, as presented in the video you provided, seems to be wrong. At least it never happened the way, the speaker wants to make us believe.

Chapter from the Wikipedia Article about the Double-slit experiment:

"Which-way" experiments and the principle of complementarity

A well-known thought experiment predicts that if particle detectors are positioned at the slits, showing through which slit a photon goes, the interference pattern will disappear.[ 2] This which-way experiment illustrates the complementarity principle that photons can behave as either particles or waves, but cannot be observed as both at the same time.[33][34][35] Despite the importance of this gedanken in the history of quantum mechanics (for example, see the discussion on Einstein's version of this experiment), technically feasible realizations of this experiment were not proposed until the 1970s.[36] (Naive implementations of the textbook gedanken are not possible because photons cannot be detected without absorbing the photon.) Currently, multiple experiments have been performed illustrating various aspects of complementarity.[37]

An experiment performed in 1987 [38][39] produced results that demonstrated that information could be obtained regarding which path a particle had taken without destroying the interference altogether. This showed the effect of measurements that disturbed the particles in transit to a lesser degree and thereby influenced the interference pattern only to a comparable extent. In other words, if one does not insist that the method used to determine which slit each photon passes through be completely reliable, one can still detect a (degraded) interference pattern.[40]

[ 2] Feynman, Richard P.; Robert B. Leighton; Matthew Sands (1965). The Feynman Lectures on Physics, Vol. 3. US: Addison-Wesley. pp. 1.1–1.8. ISBN 0201021188.

[33] Harrison, David (2002). "Complementarity and the Copenhagen Interpretation of Quantum Mechanics". UPSCALE. Dept. of Physics, U. of Toronto. Retrieved 2008-06-21.

[34] Cassidy, David (2008). "Quantum Mechanics 1925–1927: Triumph of the Copenhagen Interpretation". Werner Heisenberg. American Institute of Physics. Retrieved 2008-06-21.

[35] Boscá Díaz-Pintado, María C. (29–31 March 2007). "Updating the wave-particle duality". 15th UK and European Meeting on the Foundations of Physics. Leeds, UK. Retrieved 2008-06-21.

[36] Bartell, L. (1980). "Complementarity in the double-slit experiment: On simple realizable systems for observing intermediate particle-wave behavior". Physical Review D 21 (6): 1698. Bibcode:1980PhRvD..21.1698B. doi:10.1103/PhysRevD.21.1698.

[37]Zeilinger, A. (1999). "Experiment and the foundations of quantum physics". Reviews of Modern Physics 71 (2): S288. Bibcode:1999RvMPS..71..288Z. doi:10.1103/RevModPhys.71.S288.

[38] P. Mittelstaedt; A. Prieur; R. Schieder (1987). "Unsharp particle-wave duality in a photon split-beam experiment". Foundations of Physics 17 (9): 891–903. Bibcode:1987FoPh...17..891M. doi:10.1007/BF00734319.

[39] D.M. Greenberger and A. Yasin, "Simultaneous wave and particle knowledge in a neutron interferometer", Physics Letters A 128, 391–4 (1988).

[40] Wootters, W. K.; Zurek, W. H. (1979). "Complementarity in the double-slit experiment: Quantum nonseparability and a quantitative statement of Bohr's principle" (PDF). Phys. Rev. D 19 (473–484). Bibcode:1979PhRvD..19..473W. doi:10.1103/PhysRevD.19.473. Retrieved 5 February 2014.

  • $\begingroup$ This is the correct answer, it never happened that way. This leads to the next question, why would you consider detectors on/off as having the same environment conditions. $\endgroup$
    – Nick
    Jun 8, 2016 at 6:36
  • $\begingroup$ We have to remember that we are talking about the detectors at the slits. Back when the Gedankenexperiment was proposed it was unknown how these detectors could look like. So if you have to pick out a proposed "photon fly by" detector of [37-39] and discuss the properties of this proposal. $\endgroup$
    – user_na
    Jun 8, 2016 at 7:17

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