Yesterday I posted an animation of a quantum wave function, and as a brain teaser, I asked readers to see if they could interpret it. Here it is again:
Admittedly, it’s a classic trap — one I use as a teaching tool in every quantum physics class. The wave function definitely looks, intuitively, as though two particles are colliding. But no. . . the wave function describes only one particle.
And what is this particle doing? It’s actually in the midst of a disguised version of the famous double slit experiment! This version is much simpler than the usual one, and will be super-useful to us going forward. It will make it significantly easier to see how all the puzzles of the double-slit experiment play out, both from the old, outdated but better known perspective of 1920’s quantum physics and from the modern perspective of quantum field theory.
You can read the details about this wave function — why it can’t possibly describe two particles, why it shows interference despite there being only one particle, and why it gives us a simpler version of the double-slit experiment — in an addendum to yesterday’s post.
5 Responses
Can the double slit experiment also explain quantum tunneling? Refraction could be thought of as a flow of energy around barriers, including different flux densities of the same particles, so it shouldn’t take that much difference in potential to “flow” over what may seem as improbably higher potential.
If this “flow” is actually happening then doesn’t that suggest that even the photons are composite particles, “wavicles”?
Quantum tunneling is a different issue — and doesn’t really need explanation, it’s well understood. The double slit experiment is more confusing than tunneling.
Well, my understanding of the double slit experiment is that the wave function “collapses” when it’s observed, i.e. waves morph into particles. So, I compared it to quantum tunneling because it seems that in both cases the waves get “polarized” in a sense that interference creates a flux profile that morph them into particle-like characteristics.
I guess I am fixated into this theory that in order for energy to get trapped and form fermions from bosons, even photons must be composites “glued” together by a unified force which I think could be quantum gravity, the graviton.
How does the wave function collapses in the double slit experiment?
I’m going to explain this very precisely, probably in about ten days. Stay tuned.
I’ve got to admit you got me. I fell for the obvious, but wrong, interpretation, even though I should have known better.
I’m very much looking forward to your explanation in terms of QFT. I learned QFT from David Tong’s online lectures (most of the textbooks on the subject are completely impenetrable to me – even the ones aimed at amateurs like myself). Excellent though David’s lecture are, they deal exclusively with scattering and decay rates. So it will be very interesting to see the techniques applied to the double slit experiment.
Thank you for all the hard work that you put into these posts. They are most enlightening.
p.s. I’m still hoping to post a picture of T Cor Bor when it finally goes bang. Although I’ve given up looking out for it every night like I used to.