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We typically use either Heisenberg's Uncertainty Principle or Schrödinger's Cat when we want to talk about a situation where you can't observe a state without altering it.

A good example of this situation is the question: Am I interrupting you?

The question itself is an interruption, but you can't know the state of the person (amenable to interruption or not) until you ask.

It's been my experience that using Heisenberg or Schrödinger is likely to earn you a lecture from the nearest pedant. Removing every person in my life who's fond of the phrase "Well, actually..." is not an option because:

  1. I work in tech
  2. I'm one of them

But I'd love it if this community could supply me with whatever idiom we used to evoke this situation before our two estimable German friends came along.

Because I found success with this approach in my last idiom question, I'm going to put some near misses here:

Near Misses

  • "catch-22" - Too general. I'm after a more specific sense of the inability to observe a state without changing it (which itself is a catch-22).

marked as duplicate by Hellion, user66974, FumbleFingers, TimLymington, Edwin Ashworth Mar 11 '15 at 15:12

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The observer-expectancy effect is when a researcher unintentionally changes the behavior of the subject(s) he or she is trying to observe.

Similarly, the Hawthorne effect is when subjects change their behavior because they know they're being observed, making it impossible for the observer to observe the subjects' natural behavior.


Would you consider this a near miss?

You can't make an omelette without breaking a few eggs.

Alternatively, you could just cite Shrödinger's cat:

You: Am I interrupting you?
Them: By asking me that question, you interrupted me, so .. yes.
You: Ha ha, yeah; it's like Shrödinger's cat.
Them: Well, actually it—


You can't eat a cake and have it too.

From The Quantum Guide to Life by Kunal K. Das.

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