The way I understand delayed choice quantum eraser is the puzzling issue, how the future entangled photons being detected or not effects the behavior of the signal photon in the past?
If I understand that wrong and that is not what it is about then what I am about to ask is not a meaningful inquiry.

So it means this to me:

I am watching a double slit experiment and I notice interference pattern or I am seeing particle like pattern if there is a detector there. One or the other. So that is that.

However I am blissfully unaware that these photons are signal photons and they have entangled partners and are still in flight. And some will be detected and some won't.

As I am watching, suddenly I see the photons begin to change in their configuration and two groups are formed. One group begins to show interference and another group, particle like pattern.

That is what I call the future effecting the past. But chances are I am wrong, because I am actually describing the situation how the future is effecting the present and that is not what the experiment says.

If this is the case then I wonder if they have done an experiment to see if the future can effect the present.

Or is it that I am sitting to watch the screen of signal photons detector and I wonder why it is blank, nothing is showing. Only to realize that the signal photons has frozen in midflight because they have entangled partners and their destiny is still unknown whether they are going to be detected or not.

Please do not assume I am being silly here and make light of things.

Instead of closing this post, please give someone else a chance if they can see some meaning to my inquiry. I am not doubting the integrity of science and the integrity and hard work of those doing the experiment and interpreting the findings.

There is nothing wrong with asking questions even if the question is meaningless. Please let me know why my inquiry is meaningless. I appreciate that.

  • $\begingroup$ You are not being silly. Try reading this paper on Arxiv, which is related to your question. I have a feeling that it will help. $\endgroup$
    – Gilbert
    Aug 2, 2021 at 0:57
  • $\begingroup$ As Gilberts referenced paper states there is no future predicting phenomenon ... the quantum eraser type experiments are interesting but when looked at from a more in-depth perspective their claims are debunked. $\endgroup$ Aug 2, 2021 at 19:40

1 Answer 1


An individual watching the screen does not see any interference pattern, even if the photons are later detected in a way which is wavelike.

Wikipedia actually has a pretty good image showing this.

The screen detector does not see any interference pattern. However, if you know which photons to look for to see wave patterns (i.e. path erasure occurs), you will indeed see the interference pattern. However, unless you have a crystal ball, you won't know which photons to look for until after the other detectors have done their work. Thus, no "future affecting the past."


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