This evening, Thursday June 6th at 6:30 pm, I’ll be joined at the Boston Public Library by Sarah Demers, professor at Yale and member of the ATLAS experiment, and Katrina Miller, Ph.D. in neutrino physics and writer for, among other publications, the New York Times. We’ll serve on a panel entitled “Particle Physics: Where the Universe and Humanity Collide”, talking about the future of particle physics and about how we got into physics in the first place. This event, intended for the general public, is part of the international scientific meeting that I’m attending this week, the 12th annual Large Hadron Collider Physics conference. I hope to see some of you there!
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I’m enjoying reading “Waves In an Impossible Sea”, it’s the book of the month in my local popular science book reading club. I’m on chapter 17 but slightly puzzled.
I usually see the uncertainty principle explained in terms of the quantum wave function, and similarly the electron orbitals in atoms described with wave functions. Instead, in chapter 17 you seem to describe both these in terms of ripples (wavicles) in the electron field.
In the double slit experiment, would it also be explained it in terms of waves in the electron field, or would one have to use the quantum wave function in this case ?
So this goes to the heart of the difference between quantum mechanics (quantum physics of localized objects) and quantum field theory. And it does not have an easy answer because quantum field theory is hard to visualize.
The question is: how does the wave function that describes particles in quantum mechanics relate to the wave function that describes wavicles in quantum field theory, and the wavicles themselves? And what is the best way to gain intuition about them?
A clue is already that for electrons passing through the double-slit experiment treated in non-relativistic quantum mechanics, the mathematical description is of one sort, whie for photons passing through the double-slit experiment, there is a different type of treatment — because you can’t describe photons using non-relativistic quantum mechanics.
In quantum field theory, electrons are treated exactly the same way as photons, and the non-relativistic treatment, in which electrons are objects with position, is abandoned. Thus, the analysis of electrons using nonrelativistic quantum mechanics is not the more fundamental approach. And this is why the way you’ve learned about this physics is, in a sense, out of date by approximately seventy-five years. It’s also why Bohr’s views are out of date by a similar degree.
More precisely, quantum mechanics is still a perfectly good way to describe the system as long as you don’t ask too many questions. But if you want simultaneously to be able to talk about the double-slit experiment, atomic physics, and particle scattering or annihilation, then at some point the quantum mechanics view is going to break down, and you’ll need the more modern view, which is a wave function of wavicles, not of particles. The challenge there is not to understand how the object goes through two slits — that’s the easy part, because waves always do that. The challenge is to understand why, when the photon or electron reaches the screen, it interacts with only one atom (or a small number of nearby atoms). And so, in my view, it changes the emphasis of the problem. It certainly doesn’t eliminate it.
Keep up the good work, Mind and its product, Thought, enjoy ‘increase’