How do you measure a particle's postion or momentum?

Question

This question is about the Uncertainty Principle

$$sigma_x sigma_p ~ge ~frac{hbar}{2}.$$

Looking at the maths, I understant why the uncertainty in the poistion increases as the uncertainty in the momentum decreases and vice versa, but I don't understand it in terms of an experiment.

For starter, how do you measure a particle's position or momentum? What is stopping me from making two simultaneous measurements, one for position and one for momentum?

(I understand that the Uncertainty Principle is a natural phenomenon, not a limitation of our technology.)

anna v · Answer

There is nothing like bubble chamber photos to clarify such issues.

Here is an anti Lamda:

The part relevant to your question is that we can measure with an accuracy of microns the vertex of the decaying antilamda, and with an accuracy of an MeV/c  the momenta of the particles it decays into, an antiproton and a pion. The antiproton identifiable by ionisation and the interaction into five pions .  The Heisenberg Uncertainty Principle ,HUP, is fulfilled because the experimental accuracies are much larger than the constraints of the uncertainty principle. This holds true for all measurements in particle physics detectors.

So nothing is keeping you except the crudeness of real measurements with respect to the HUP.

For testing the HUP special experimental setups have to be devised .

This link shows how using the HUP one can estimate energy levels in nuclei and atoms.

How do you measure a particle's postion or momentum?

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