Electromagnetism

What charge is

The electron doesn’t have an electric field, it has an electromagnetic field. If you’re a positron and I set you down near a motionless electron, you will move linearly towards it, and it will move linearly towards you. So you might think the electron has a radial electric field, which results in a linear electric force. But it doesn’t. That linear force is there because the electron has an electromagnetic field, and so does the positron. Linear and rotational force Moreover the interaction between these fields…

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Why magnetic monopoles do not exist

There’s a lot of articles about magnetic monopoles. See this for example: the hunt for magnetism’s elementary particle begins. It dates from 2016, and it’s by Avaneesh Pandey. He says this: “magnets, for reasons we still do not understand, seem to exist only in the form of dipoles - ones with a north and a south end. Break a bar of magnet into two, and you still do not get a magnetic monopole. Instead, you now have two smaller magnets, each with its north and south…

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How a magnet works

There's a rather interesting Discover magazine article called Three Words That Could Overthrow Physics: “What Is Magnetism?”. It was written by Bruno Maddox in 2008. The subtitle is "The standard model still doesn't describe magnets' spooky action at a distance". Maddox was on holiday reading Electronics for Dummies when he realised that he didn't how a magnet works. He said this: "I set out on what I assumed would be a minutes-long odyssey to understand the phenomenon. Seventy-one days later, I am here with astonishing findings.…

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The screw nature of electromagnetism

If you’ve ever read Maxwell’s On Physical Lines of Force, you may have noticed this: “a motion of translation along an axis cannot produce a rotation about that axis unless it meets with some special mechanism, like that of a screw”. Maxwell was referring to what I can only describe as the screw nature of electromagnetism. If you have a pump-action screwdriver you’ll appreciate that linear force is converted into rotational force. That’s like an electric motor: current flows through the wire, and the motor turns.…

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The positron

The positron is usually described as a fundamental or elementary particle. That doesn’t tell you much, but when you look for more information, it’s rather scant. You soon learn that the positron  has a mass of 9.109 x 10-31 kg or 511keV/c². You learn that it has a charge of 1.602 x 10−19 Coulombs or +1e, the e being elementary charge. You also learn that it has spin ½. However you don’t learn much else. Particularly since the particle data group doesn’t have a listing for…

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The electron

The electron is usually described as a fundamental or elementary particle. That doesn’t tell you much, but when you look for more information, it’s rather scant. You soon learn that the electron has a mass of 9.109 x 10-31 kg or 511keV/c². You learn that it has a charge of −1.602 x 10−19 Coulombs or -1e, the e being elementary charge. You also learn that it has spin ½. However you don’t learn much else. Instead you get mixed messages. Take a look at the enigmatic electron…

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How pair production works

Yes, there's a hole in the heart of quantum electrodynamics because it describes the interaction between light and matter, but not the interaction between light and light. That's the interaction that creates matter in gamma-gamma pair production. QED misses the crucial point that waves interact. Even though we've all seen waves interact, down on the beach. Imagine a big wave is coming towards you. You make a little wave with your hand and send it scooting towards the big wave: The little wave rides up and over…

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The hole in the heart of quantum electrodynamics

Pair production is the creation of a particle and its antiparticle. Some say it was first observed in 1929, but it's usually accredited to Carl Anderson in 1932. He used a cloud chamber and an electromagnet to investigate cosmic rays. He effectively split a gamma photon over an atomic nucleus to create an electron and an antielectron. He called the latter the positive electron, which was soon shortened to positron: Image from schoolphysics However whilst he realised that he’d discovered the positron, he didn’t realise that he’d performed pair…

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The photon

The photon has a wave nature, which is why we can refract and diffract light. But what sort of a wave nature? When you try to find a picture, a lot of illustrations depict the photon as some kind of wave train. Even Feynman diagrams do this. Image by bitwise, see Wikipedia commons The photon is shown as a squiggly line, sometimes with an arrowhead, something like this: ⇝. That suggests you could split a photon lengthwise and end up with two photons, each with the…

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What is a photon?

OK, so quantum electrodynamics is said to date from 1929 when it was the same thing as quantum field theory. However it immediately suffered from the “problem of infinities”. So much so that some say most workers in the field doubted its correctness, whilst others say physicists believed a conceptual change was needed. As to what, see the conceptual foundations and the philosophical aspects of renormalization theory by Tian Yu Cao and Silvan Schweber dating from 1993. They say QFT embodies a reductionist view, but “serious doubt has often been cast on the…

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