Seeing antimatter for the first time
Four years later, in California, Carl Anderson was using a cloud chamber to do experiments with protons, neutrons and electrons. An electron is much too small to see, but when it passes through a cloud chamber it leaves a distinctive spiral trail. The shape of the spiral is always the same, and its direction is always the same.
In 1932, Carl Anderson saw a spiral trail that looked like an electron, but like an electron spinning in the “wrong” direction. He’d found the proof that Paul Dirac’s “positive electron” existed.
Just four years after Paul Dirac’s mathematical prediction, Carl Anderson had shown that antimatter was real. Anderson invented the name “positron” for the positive electron, and the name stuck.
Dirac and Anderson both received the Nobel Prize for Physics: Dirac for his theoretical prediction, and Anderson for the practical proof.