All Questions

19 questions
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Heisenberg uncertainty principle meaning and using it to determine approximate sizes confusion

I was always under the impression that the Heisenberg uncertainty principle tells us to what precision we can make a momentum measurement given a position one. However, when doing quantum mechanics ...
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Relation between momentum and momentum uncertainty

I have read the following sentence in a section which is explaining why particle accelerators need such high energy: As we require high precision position measurement, the Heisenberg uncertainty ...
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Is the uncertainty principle a circular argument? [closed]

Uncertainty is due to the measurement techniques humans tend to use requiring photoelectric effect. The Planck constant is due to the photoelectric effect. If the standard deviation of measurement was ...
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Does every interaction of quantum objects introduce backaction?

The motivation of this question is the following experiment: Assume you have quantum mechanical oscillator, e.g. a particle in a potential $V(q_x)\propto q_x^2$. Now the position of the particle ...
4k views

What is the experiment used to actually observe the position of the electron in the H atom?

Prior to observation, the electron can be found anywhere (from inside the nucleus to the ends of the universe), but once its position is determined the answer is precise (albeit its momentum is not ...
755 views

Repeating a measurement vs uncertainty

The wikipedia says on measurement in quantum mechanics that: Repeating the same measurement without any evolution of the quantum state will lead to the same result. On the other hand, doesn't ...
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can one measure energy to a finite accuracy?

Can one measure energy to a finite accuracy in a bounded amount of time? I don't know much about QM, but someone told me that the energy-time uncertainty principle says that it would take an infinite ...
956 views

Measuring position and momentum at the same time?

In a non-relativistic quantum mechanical system in an infinite potential well. I try to measure the energy and the position of the system simultaneously. Since, the respective operators do commute ...
829 views

Uncertainty principle with two photons

Imagine an experimental setup in which you have to measure the momentum and location of a particle. To measure it we know we will have to affect it, and the uncertainty principle would come into the ...
2k views

Is the Uncertainty Principle valid for information about the past?

My layman understanding of the Uncertainty Principle is that you can't determine the both the position and momentum of a particle at the same point in time, because measuring one variable changes the ...
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Shouldn't the Uncertainty Principle be intuitively obvious, at least when talking about the position and momentum of an object?

Please forgive me if I'm wrong, as I have no formal physics training (apart from some in high school and personal reading), but there's something about Heisenberg's Uncertainty Principle that strikes ...
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Uncertainty on a single observable measurement

Heisenberg Uncertainty Principle states (in the form of the Robertson-Schroedinger Formula) that measurement of two non-commuting observables has a limiting precision, even for flawless measurement ...
I need to confirm whether or not I understand Heisenberg Uncertainty Principle. So the crucial thing is that you need an "ensemble" of measurements: $$\delta x \delta p \ge \frac{\hbar}{2}.$$ If I ...