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a question about light and uncertainty:

If a laser beam has a 2 cm diameter when it passes through an aperture that is 6 cm wide, the beam is not affected by the aperture.

Why? What happens to the uncertainty principle there?

Isn't the probability wavefunction affected by the edges of the aperture causing a larger momentum uncertainty?

For a laser beam all the photons belong to the same quantum state, or almost, and so the diffraction spread of a single photon represents the spread of the whole beam.

thanks!

fisico30

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# Laser beam uncertainty

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