Today In Science History – August 8 – Paul Dirac 2

Paul Dirac
Paul Dirac (1902 -1984) Theoretical physicist and pioneer of quantum electrodynamics.

August 8 is Paul Dirac’s birthday. Dirac was an English physicist and one of the founders of quantum electrodynamics. He was instrumental in laying out the mathematics behind atomic theory to relativistic speeds. He derived the wave functions for relativistic electrons and for electron spin.

During the early part of the 20th Century, physics underwent a fundamental transformation from Newton’s classical physics. Einstein showed Newton’s classical physics failed at speeds approaching the speed of light and introduced us to relativity. Shrödinger showed Newton’s physics failed on the microscopic scale and introduced quantum mechanics. Paul Dirac united the two discoveries. Dirac’s equations showed electrons have spin and are magnetic, explaining the hyperfine spectra of the hydrogen atom. A side note of his equations theorized the existence of a new form of matter consisting of negative energy, or anti-matter solutions to the wave equation. This was a sticking point in Dirac’s theory since no one had seen a particle with the same mass as an electron and a positive charge. At least until Carl Anderson discovered the positron in 1932. This concrete proof of his theories was one of the largest achievements in theoretical physics of the time. It would be enough to earn him part of the 1933 Nobel Prize in Physics.

By all accounts, Paul Dirac was not a chatty man. His coworkers at Cambridge named the unit of one word per hour as a Dirac. He found social functions a trying task and hated being forced into social situations he wanted no part of. During a trip to Japan, he traveled with Werner Heisenberg who was outgoing and enjoyed dancing with the ladies. Dirac asked him why he liked dancing. Heisenberg said that dancing was a pleasure when the ladies are nice. Dirac asked him how he knew the ladies were nice beforehand. During a lecture at a conference, an attendee said: “I don’t understand the equation on the top-right hand corner of the blackboard”. Dirac did not immediately address the attendee and the moderator asked if he was going to answer the question. Dirac replied, “That was not a question. It was a statement.”

Other Notable Events For August 8

1996 – Nevill Francis Mott died.

Mott was an English physicist who shared the 1977 Nobel Prize in Physics with Philip W. Anderson and J. H. Van Vleck for their independent work with the electronic structure of magnetic and disordered systems. A disordered system is a solid with no long range order to the group of molecules that make up the solid. Glass is an example of a disordered system.

1973 – Feodor Lynen died.

Feodor Lynen
Feodor Lynen (1911 – 1979)
Credit: Creative Commons

Lynen was a German biochemist who shares the 1964 Nobel Prize in Medicine with Konrad Bloch for research concerning the metabolism of cholesterol and fatty acids.

1902 – Paul A. M. Dirac was born.

1901 – Ernest Orlando Lawrence was born.

Ernest Lawrence (1901 - 1958)
Ernest Lawrence (1901 – 1958)
Credit: Nobel Foundation

Lawrence was an American physicist who was awarded the 1939 Nobel Prize in Physics for the development of the particle accelerator and the development of artificial radioactive elements. He invented the cyclotron particle accelerator where charged particles are accelerated using a high-frequency alternating voltage and a strong perpendicular magnetic field. As the particles accelerate, they make a spiral pattern as they enter and leave the accelerating field. Lawrence Livermore Laboratory and the element lawrencium were named in his honor.

1897 – Viktor Meyer died.

Viktor Meyer (1848 - 1897)
Viktor Meyer (1848 – 1897)

Meyer was a German chemist who created a device to accurately determine vapor densities of inorganic substances at high temperatures. This allowed him to make accurate measurements of atomic weights of elements. He also discovered the heterocyclic compound thiophene while investigating the vapor density of benzene.