Photon

Misconceptions in particle physics

Physics is said to be the king of the sciences, and particle physics is said to be the most important branch of physics. As per the Wikipedia particle physics article, it’s the branch of physics that studies the nature of the particles that constitute matter and radiation. The article tells us that elementary particles are excitations of the quantum fields, and says this: “the currently dominant theory explaining these fundamental particles and fields, along with their dynamics, is called the Standard Model”. Glenn Starkman gives a…

Continue ReadingMisconceptions in particle physics

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…

Continue ReadingHow pair production works

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…

Continue ReadingThe hole in the heart of quantum electrodynamics

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…

Continue ReadingThe photon

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…

Continue ReadingWhat is a photon?