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James Cronin, who explained why matter survived the Big Bang, dies at 84

1951 graduate of SMU


The following is from the Aug. 30, 2016, edition of The New York Times.

August 27, 2016

By Sam Roberts

James CroninJames W. Cronin, a physicist who shared a Nobel Prize for repudiating a fundamental principle of physics and explaining why the universe survived the Big Bang with anything in it, died on Thursday in St. Paul. He was 84.

In 1964, Dr. Cronin and Val Fitch of Princeton University were conducting experiments at Brookhaven National Laboratory on Long Island involving matter and antimatter: particles that have the same mass but hold opposite (though equal) charges, either positive or negative, compelling them to destroy each other on contact.

The researchers found that for all their similarities, the particles obeyed slightly different laws of physics: that there was, as Dr. Cronin put it, “a fundamental asymmetry between matter and antimatter.”

This contradicted a bedrock scientific principle known as charge-parity invariance, which had assumed that the same laws of physics would apply if the charges of particles were reversed from positive to negative or vice versa.

The finding, known as the Fitch-Cronin effect, bolstered the Big Bang theory, mainly by explaining why the matter and antimatter produced by the explosion did not annihilate each other, leaving nothing but light instead of a residue that evolved into stars, planets and people. . . 

Dr. Cronin’s infatuation with physics began in high school. He graduated in 1951 from Southern Methodist, where he majored in physics and mathematics. He received a doctoral degree from the University of Chicago, where he studied under Enrico Fermi, Edward Teller and Murray Gell-Mann. His thesis was on experimental nuclear physics.

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