{"id":13853,"date":"2021-11-25T09:00:56","date_gmt":"2021-11-25T17:00:56","guid":{"rendered":"https:\/\/www.preposterousuniverse.com\/blog\/?p=13853"},"modified":"2021-11-25T09:01:03","modified_gmt":"2021-11-25T17:01:03","slug":"thanksgiving-16","status":"publish","type":"post","link":"https:\/\/preposterousuniverse.com\/blog\/2021\/11\/25\/thanksgiving-16\/","title":{"rendered":"Thanksgiving"},"content":{"rendered":"\n

This year we give thanks for something we’ve all heard of, but maybe don’t appreciate as much as we should: electromagnetism. (We’ve previously given thanks for the Standard Model Lagrangian<\/a>, Hubble’s Law<\/a>, the Spin-Statistics Theorem<\/a>, conservation of momentum<\/a>, effective field theory<\/a>, the error bar<\/a>, gauge symmetry<\/a>, Landauer’s Principle<\/a>, the Fourier Transform<\/a>, Riemannian Geometry<\/a>, the speed of light<\/a>, the Jarzynski equality<\/a>, the moons of Jupiter<\/a>, space<\/a>, and black hole entropy<\/a>.)<\/p>\n\n\n\n

Physicists like to say there are four forces of nature: gravitation<\/a>, electromagnetism<\/a>, the strong<\/a> nuclear force, and the weak<\/a> nuclear force. That’s a somewhat sloppy and old-fashioned way of talking. In the old days it made sense to distinguish between “matter,” in the form of particles or fluids or something like that, and “forces,” which pushed around the matter. These days we know it’s all just quantum fields<\/a>, and both matter and forces arise from the behavior of quantum fields interacting with each other. There is an important distinction between fermions and bosons, which almost maps onto the old-fashioned matter\/force distinction, but not quite. If it did, we’d have to include the Higgs<\/a> force among the fundamental forces, but nobody is really inclined to do that.<\/p>\n\n\n\n

The real reason we stick with the traditional four forces is that (unlike the Higgs) they are all mediated by a particular kind of bosonic quantum field, called gauge fields. <\/a>There’s a lot of technical stuff that goes into explaining what that means, but the basic idea is that the gauge fields help us compare other fields at different points in space, when those fields are invariant under a certain kind of symmetry. For more details, check out this video from the Biggest Ideas in the Universe<\/a> series (but you might need to go back to pick up some of the prerequisites).<\/p>\n\n\n

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The Biggest Ideas in the Universe | 15. Gauge Theory<\/div><\/div>
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