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 it. It has a listing for the electron, but not for the positron. However once you know what the electron is, it’s easy to work out what a positron is. The key word is chirality. Chirality is “handedness”. Google on positron chirality. The positron has the opposite chirality to the electron. What else is chiral? Knots. You can tie your shoelaces left-over-right or right-over-left. What else? A Möbius strip: it’s a chiral object with right or left handedness”. When you make a Möbius strip you can twist clockwise or anticlockwise before taping the ends together. One is a mirror image of the other:


Note though that the positron isn’t quite a mirror-image of the electron because electrons and positrons are dynamical. You can play around with gifs, see for example ezgif. You can do a flip horizontal, but it doesn’t quite satisfy. Not until you reverse the gif. You play it backwards:


Gifs by Adrian Rossiter, see his torus animations

In this sense the positron is a time-reversed electron. It isn’t moving backwards in time, as per Wheeler’s one electron universe. Wheeler did however talk about a tangled knot and lines, half of which have looped round and are directed backwards. So perhaps he was getting warm, especially since he also talked about the geon. He “suggested that these backwards sections appeared as the antiparticle to the electron, the positron”. Feynman said he stole this idea for The Theory of Positrons in 1949. He said pair production was the time-reverse of annihilation, which is true. But see the Feynman-Stueckelberg interpretation which dates from 1941. When Feynman said the positron was a time-reversed electron he was thinking of travelling backwards through time, and there is no such thing. But when you understand the nature of time, you know that there is no backward motion through time because there is no forward motion through time. The motion is through space. And because the motion is chiral and it goes the other way, the positron has the opposite charge. That’s it. That’s all you need to know about the positron. You have a left hand, and a right hand, they have a handedness. So do fermions, so do enantiomers, so do cyclones. And so do screws.


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