The Early Days of a Better Nation

Tuesday, March 03, 2009

See into the quantum world!

This is a one way cool effect, and astoundingly simple and easy. We should show this to children.


The effect is terrific. Do we know if the author is correct in what's going on -- that we're demonstrating the wave nature of light, or if it's just the blurring of the unfocused edges of your fingers?

I'm delighted but skeptical.

The lines seem to be too many, too distinct, and too parallel to be blurring.

It would be an interesting exercise to make an approximation the width of the gap and the number of lines, and then see if you can work out the wavelength.

I spotted this for myself before I was a teenager, and even worked out the likely explanation a bit later. There's an even easier way to set it up (for people with short fingernails). Press each forefinger and thumb together, then press the pairs together to leave a small lozenge shaped gap which can be tightened up. Look through that. You shouldn't call this a quantum effect, though; the classical wave theory of light is enough for it, and it doesn't need the light to be quantised.

Where is the proof that this ia a QM effect? Several years ago an American physicist did some experiments whose outcomes were partly similar to what's described here. That scientist claimed that his results refuted some standard interpretation of QM (I think Copenhagen). It was reported on in NEW SCIENTIST and the result was a snowstorm of letters purporting to explain the phenomena in terms of CLASSICAL diffraction patterns. My physicist friends told me that the classical accounts won the debate. Perhaps the present case also has a classical explanation. I don't know. But the quick jump from a simple description of the set-up to a QM analysis makes me suspicious.

I was being flippant about seeing into the quantum world. The original link only mentioned the wave theory of light, which is classical.

You are all too right, Ken. I read too fast and noticed the restriction to the wave theory later. Mea Culpa this time.

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