Arthur Compton’s Discoveries in This World and Beyond

Nobel Prize Winner in Physics Introduces the ‘Compton Effect’

Arthur Compton’s theory and equation demonstrated the dual nature of light. Rays of light in motion. Maxim Studio/Shutterstock

Days before an important conference in 1923, Arthur Compton was sitting in his room late one night. He was exhausted, but his mind kept racing about what his discovery meant. He knew that his theory would be huge, bigger than anything he had discovered in the past. Then he prayed.

Deeply religious his whole life, Compton considered missionary work before going to college, but his father had seen his son’s genius for scientific inquiry even at a young age. When he was 12, Compton developed a fascination for astronomy. At 17, he took a picture of Haley’s Comet using a homemade camera.

His father convinced Compton that he could better serve Christianity as a scientist. Compton eventually agreed. He would soon join his two brothers at Princeton, where he explored new horizons in physics.

Arthur Compton (L) at the University of Chicago in 1933 with a graduate student next to his cosmic ray telescope. Public Domain

The Nature of Light

At Princeton, Compton impressed his colleagues with a unique way to demonstrate the earth’s rotation. He graduated from Princeton in 1916 with a doctorate in physics. Hw accepted a position as a professor of physics at the University of Chicago in 1923 and there studied the properties of light.

During his research, he made his groundbreaking discovery. Physicists already knew that light moved from Point A to Point B like a wave. But through his studies, Compton proved there was more: Light could behave as both a particle and a wave.

Other scientists did not accept his premise that light could have a dual nature. When he presented his theory at an American Physical Society meeting in late 1923, his idea caused a storm of controversy. Compton responded by developing an equation that would prove his hypothesis.

Arthur Compton on the cover of Time magazine on Jan. 13, 1936, holding his cosmic ray detector. Wide World Photos. Public Domain

He tested his equation and demonstrated that, when x-rays collided with electrons in certain types of metals, their frequency would reduce, and their wavelengths would grow. This meant that the x-rays lost energy. The fact that energy transferred from a photon, or particle of light, to an electron was coined the “Compton effect.” With this discovery, in 1927 the Nobel Committee awarded Compton with the Nobel Prize in Physics.

Atomic Research

Compton used his recently gained knowledge to turn his focus on cosmic rays. He had traveled 40,000 miles around the world to observe cosmic rays in different locations. He found that the largest numbers of cosmic rays existed far away from the earth’s magnetic equator. This proved that cosmic rays consisted largely of charged particles.

His research in the next decade took another turn, as chaos threatened countries around the world.  The United States had not yet joined the conflict in Europe when Nazi Germany invaded Poland in 1939, but calls to join the war effort intensified over the next year. Although Compton was a devout Christian, he supported the war effort, and disagreed with his own minister, who was a pacifist and frowned upon going to war.

Diagram of Compton's experiment; scattering occurs in the graphite target on the left. The slit passes X-ray photons scattered at a selected angle. CC0

In 1941, Compton began to study the possible use of atomic energy in war. He became a project director of the Metallurgical Laboratory at the University of Chicago in 1942. There, he supervised the first nuclear chain reaction. His work with the Manhattan Project in the early 1940s would lead the way to the creation of the first atomic bomb.

In his autobiography, “The Cosmos of Arthur Holly Compton,” he said: “As long as I am convinced, as I am, that there are values worth more to me than my own life, I cannot in sincerity argue that it is wrong to run the risk of death or to inflict death, if necessary, in the defense of those values.”