The Disordered Cosmos by Chanda Prescod-Weinstein

Author:Chanda Prescod-Weinstein [Prescod-Weinstein, Chanda]
Language: eng
Format: epub
Publisher: PublicAffairs
Published: 2021-03-09T00:00:00+00:00

Footnotes

i This book inspired my first work of public writing about diversity and inclusion in physics, which fellow theoretical physicist and science communicator Sean Carroll published on his blog back in 2006. In that essay, I point out that for all of the talk about the stifling of diverse ideas in physics, there wasn’t enough discussion about the stifling of marginalized people.

NINE

THE ANTI-PATRIARCHY AGENDER

Particles themselves are nonbinary.

—Amrou Al-Kadhi

PARTICLES DON’T HAVE A GENDER, BUT IT’S TRUE, AS I HINTED in earlier chapters, that they don’t obey the binaries we might expect in a world governed by prequantum conceptions of them. Quantum physics revolutionized the way that early twentieth-century physicists saw the whole world. The best way to get an intuitive sense of the phase transition that this induced in physics thought is to discuss the famed double-slit experiment. In this experiment, a metal plate with two slits in it is set up some distance away from a wall. Either a concentrated beam of light (like a laser) or a beam of elementary particles, say electrons, is aimed at the plate. In the case of the light, we perceive it to be like a wave—something bobbing up and down through space, kind of like waves in the ocean moving toward the beach. The light patterns that you see on the wall have the same shape that one might expect from a wave, as if it split and went through both slits. But, if you zoom in closely enough, there are individual, discrete dots on the wall, as if individual particles were hitting it, not a wave.

With a beam of electrons, which traditionally physicists thought of as little point-like dots, the shape of the patterns we see on the wall look similar—what one might expect if the electrons were waves, not particles. The pattern looks like each electron went through both slits, even though we know with a discrete particle, that’s not possible. Even more weirdly, in both cases, if you attach a detector at each of the slits to look at what goes through them, the slits will detect individual particles, and the shape on the wall will be completely different from what we observe when there’s no detector. What’s going on? It turns out that light is made of particles called photons, and all particles, including electrons, exhibit wavelike behavior. Also, the act of observing the particles (such as by attaching detectors like I described above) changes what they do after we’ve looked at them.

Since discovering these fascinating features of particles, physicists have spent over one hundred years meticulously developing an understanding of the physical consequences. One result of that century of study is quantum mechanics, a core subject that all physics and astronomy undergraduates learn. Quantum field theory and the entire Standard Model of particle physics, which underpin the science described in the first two chapters of this book, are also consequences of this effort. We understand stars and a host of other phenomena in the universe because we’ve developed the machinery of quantum mechanics.

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