Revisiting the history of CPT theorem

The emergence of quantum mechanics and relativity at the beginning of the twentieth century irrevocably transformed the face of physics. While much has been published about this revolution, less is known about the history of the CPT theorem, which is essential to quantum field theory and contemporary physics.

A new research published in EPJ H by Alexander S. Blum and Andres Martnez de Velasco of the Max Planck Institute for the History of Science in Berlin examines the origins of the CPT theorem and its impact on current physics.

"CPT theorem is the statement that nothing would change  --  nobody would notice and the predictions of physics would not be altered  --  if we simultaneously replace particles by antiparticles and vice versa," Blum explains.

"Replace everything by its mirror image or more exactly: exchange left and right, up and down, and front and back, and reverse the flow of time. We call this simultaneous transformation CPT, where C stands for Charge Conjugation (exchanging particles and antiparticles), P stands for parity (mirroring), and T stands for time reversal."

Blum adds that the CPT theorem only became very relevant a few years after its discovery, according to the scenario given throughout the study.
"Originally, physicists had (tacitly) believed that nothing would change even if we do one of the three transformations mentioned above individually," the researcher explains. "In 1957, it was found that we can actually distinguish the world from its mirror image. In particular certain radioactive decays actually distinguish left from right. In time, it was found that, indeed, all three of the transformations individually actually produce noticeable differences." 

Blum finishes by stating that the moment has come to revisit the CPT theorem since young academics are becoming adept in both historical and philosophical analysis as well as the mathematical complexities of postwar physics.

Blum's research group is currently establishing itself as a center for this type of teaching, emphasizing the significance of the CPT theorem for a new generation of physicists.