A track curves the wrong way in a cloud chamber, and Anderson finds a new kind of matter

Cosmic rays raining down from space had puzzled physicists for two decades, and at Caltech, Carl David Anderson was tracking their paths through a cloud chamber wrapped in a magnet. On August 2, 1932, he caught a track that curved like an electron's but bent the wrong way, meaning it carried a positive charge. He called it the positive electron. Four years later, in 1936, Anderson won the Nobel Prize for the discovery…