Researchers get slo-mo footage of the collapse of a quantum waveform




IANAPhysicist, but could this technique be used to reduce the quantum effects that prevent unlimited transistor miniturization?


Sadly, no. Uncertainty is like Jell-o. Squeeze it in one dimension and it poots out in another.


It is an interesting article, mostly due to the fact that it never mentions Yakir Aharonov, who thought up the whole idea of weak measurements as a means of getting at information thought to be unmeasurable.

By the way, I'd be very skeptical of any understanding you came to as the result of reading an SF novel. Pretty much everything I've ever seen that builds on quantum ideas is seriously in error. Facts, it seems, get in the way of a good story.


@pjcamp: If any author has a chance to get QM right, it would be Greg Egan. Some seem to think he lets the science get in the way of the story, but I'm quite definitely hooked. He does sometimes dwell on the outskirts where theory and interpretation still is open, and outright invents additional physics in some stories, but I know of no other author who goes to the lengths he does -- up to and including JavaScript simulations of key ideas on his website... winning immense amounts of nerd cred!


That's an interesting web page. Thanks for the pointer. I might even be able to use some of the simulations in class. But in the essay on Quarantine, he says "I’ve often looked back and winced at some scientific flaws in the novel that go beyond the mere implausibility of its central premise." There follows a long description of various ways of interpreting the quantum wave function, and especially its collapse. While it hits the main historical points, it also misses a few things. Decoherence is mentioned, but as a complication to standard interpretations, whereas it actually stands as a full fledged alternative interpretation of the wave function and its collapse. There is also the bivector interpretation (which has interesting SF possibilities since it involves pre and post selection and two wave functions, one of which is propagating backward in time) and the Bohm-de Broglie interpretation where the wave function represents a nonlocal interaction between particles, not a probability at all.

All this nattering over the meaning of the wave function and the extent to which it is an element of reality (putting on my physicist hat here) sort of misses the point. It cannot be an element of reality. Wave functions live in Hilbert space, the only place in which they are mathematically consistent, and Hilbert space has an infinite number of dimensions, and there is a different one for each problem. Needless to say, we don't live in Hilbert space.

I tend these days to think of the wave function (and, indeed, all of physics) as a reality abstraction layer, similar to the hardware abstraction layer in the early days of Windows NT. Nature does what she does. Our brains are capable of using a particular set of representations to think, which cognitive scientists tell us are largely metaphors based on the sensorimotor system. Physics is a way of translating between the two. As such, the wave function is interesting less for what it tells us about external physical reality than what it tells us about the ways in which we are capable of reasoning.

The wave function belongs to us, not nature. As the novelist Italo Svevo wrote: "Nature does not calculate. She only makes experiments."


“What I am going to tell you about is what we teach our physics students in the third or fourth year of graduate school... It is my task to convince you not to turn away because you don't understand it. You see my physics students don't understand it... That is because I don't understand it. Nobody does.”
― Richard P. Feynman


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