I have heard that uncertainty was not the actual translation for the word which Heisenberg had used to describe his original principle (in German). The translated meaning is a bit different. What was the actual German word which Heisenberg had used for 'uncertainty'?

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    $\begingroup$ I’m voting to close this question because it should be moved to hsm.stackexchange.com $\endgroup$
    – my2cts
    Apr 18, 2021 at 15:57

2 Answers 2


It is called the « Unschärferelation ». Some people prefer that to the english version because uncertainty makes you think that if you made better measurements, you wouldn’t get this uncertainty, which is not the case. In fact, it is better to think about it as relation between the dispersion of the momentums and the dispersion of the positions of a particle, which product has to be greater than $\frac{\hbar}{2}$. In other words it is all about the relation of the unsharpness of these two distributions. That’s why « unsharpness relation » seems two describe it better than « uncertainty principle ».

  • $\begingroup$ Great, thanks! But what is its actual meaning in German- 'unsharpness relation'? $\endgroup$
    – Ranjan
    Dec 20, 2020 at 22:38
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    $\begingroup$ @Ranjan As a German, a literal translation from "Unschärferelation" to English would be "Blur relation" $\endgroup$
    – Jonas
    Dec 20, 2020 at 22:40
  • $\begingroup$ @Jonas Got it, thanks a lot! $\endgroup$
    – Ranjan
    Dec 20, 2020 at 22:41
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    $\begingroup$ I'm not a physicist, but a native German speaker - in day-to-day speech, "unscharf" is basically only used for photos that are out of focus ("blurred"), so that's probably the association Heisenberg was trying to convey with this naming: from a blurred photo, you can get the "big picture" of what's going on, but you can't be sure of the details... $\endgroup$
    – rob74
    Dec 21, 2020 at 7:21

In addition to Nicolas Schmid's answer, some but very few people use "Heisenbergsche Unbestimmtheitsrelation" for uncertainty relation but it actually means "indeterminacy relation". It makes a good sense though since there's an underlying indeterministic structure in quantum mechanics.


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