Posted on 04/25/2019 9:24:13 AM PDT by BenLurkin
The laws of physics are such that one photon just passes by another with zero interaction.
But in a new experiment inside the world's most powerful atom smasher, researchers got a glimpse of the impossible: photons bumping into each other.
The answer lies in one of the most inscrutable and yet delicious aspects of modern physics, and it goes by the funky name of quantum electrodynamics.
In this picture of the subatomic world, the photon isn't necessarily a photon. Well, at least, it's not always a photon. Particles like electrons and photons and all the other -ons continually flip back and forth, changing identities as they travel. It seems confusing at first: How could, say, a beam of light be anything other than a beam of light?
In order to understand this wacky behavior, we need to expand our consciousness a little...
In the case of photons, as they travel, every once in a while (and keep in mind that this is extremely, extremely rare), one can change its mind. And instead of being just a photon, it can become a pair of particles, a negatively charged electron and a positively charged positron (the antimatter partner of the electron), that travel together.
Blink and you'll miss it, because the positron and electron will find each other, and, as happens when matter and antimatter meet, they annihilate, poof. The odd pair will turn back into a photon.
For various reasons that are way too complicated to get into right now, when this happens, these pairs are called virtual particles. Suffice it to say that in almost all cases you never get to interact with the virtual particles (in this case, the positron and electron), and you only ever get to talk to the photon.
But not in every case.
(Excerpt) Read more at livescience.com ...
Yep. At minimum 2 x 512 keV gamma collision with a nucleus to form a positron-electron pair.
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