Hans Bethe
external image bethe.jpg
(From http://nobelprize.org/nobel_prizes/physics/laureates/1967/bethe-bio.html)

Born in Strasbourg, Germany on July 2, 1906, Hans Bethe was an important piece to the Manhattan Project. He learned Physics at JWG University and continued at the University of Munich as well as in Cambridge with Enrico Fermi.

His contributions to physics and chemistry have been and still are important to this day. He created the starting point for Crystal Field Theory, which is the description of the electric structure of transition metal compounds. This theory accounts for a number of properties of these compounds although it doesn’t theorize about the bonding of these compounds. He also developed the Beth Formula which is used to describe the energy loss of moving protons, particles and ions.

When the Nazis took power in Germany in 1933, Bethe left Germany to go work at the University of Manchester in England as a lecturer and then began a fellowship at the University of Bristol where he worked on a theory of deuteron, heavy hydrogen.

After working in England, Bethe moved to the United States where he took up a position at Cornell University. There, Bethe began the work that he was most recognized for. He worked at Cornell for almost the entire duration of his career. His work in nuclear physics became very well known and made Cornell Physics much better known. His accounts his works were nicknamed “Bethe’s Bible”. These articles became the standard for the subject for years to come. He also studied nuclear reactions and the carbon-oxygen-nitrogen cycle. Using his studies he was able to make his huge contribution to the idea of stellar nucleosynthesis, which is the term for nuclear reactions taking place in stars that build the nuclei in elements heavier than hydrogen. Bethe discussed the possibilities of stellar nucleosynthesis in how reactions fused hydrogen into helium. He discussed two possibilities, the proton-proton cycle and the carbon-oxygen-nitrogen cycle. The proton-proton cycle is the main energy source with stars smaller than our sun. The carbon-oxygen-nitrogen cycle is the source in very massive stars. His work also helped him to further the idea of a compound nucleus with protons and neutrons in the center surrounded by electron clouds.

Hans Bethe was dedicated to serving in the World War II effort. He worked at a weapons design laboratory, Los Alamos, as part of the Manhattan Project. While he was originally skeptical of the idea of the atomic bomb, he was convinced to work by Robert Oppenheimer to help work on the atomic bomb. Bethe’s work here was centered on calculating the critical mass of uranium-235, which is the lowest amount of material needed to sustain a nuclear chain reaction. He also helped calculate the multiplication of nuclear fission in the bomb, which is the power of the splitting of the atoms. His work also led him to calculate the explosive yield of atomic bomb. After the atomic bomb was first detonated, he didn’t care much for the moral implications and commented, “I am not a philosopher.” He later helped work on the plutonium and hydrogen bombs although he opposed further creation of nuclear bombs. He was awarded the Nobel Prize in Physics in 1967 for his work in nuclear reactions, especially for energy production in stars.