Today In Science History – December 5 – Heisenberg Uncertainty Principle

Werner Heisenberg
Werner Heisenberg (1901 – 1976)

December 5 is Werner Heisenberg’s birthday. Heisenberg was a German physicist who is best known for the uncertainty principle of quantum mechanics.

The uncertainty principle is one of the main differences between the study of classical mechanics and quantum mechanics. In classical mechanics, a physical quantity can be simultaneously assigned to any particle. In quantum mechanics, the uncertainty principle states the more closely you measure the momentum of a particle, the less certain you can measure the position.

An example of this would be if a microscope was used to measure the position of a particle, the measurement would have an accuracy dependent on the wavelength of the light used to take the measurement. When the light strikes the particle and is reflected back to you to record, it imparts energy to the particle and changes its momentum. The shorter the wavelength used by the microscope, the better the resolving power to pinpoint the position. Unfortunately, the shorter wavelength means more energy is involved in the collision with the particle and the less can be known of its momentum.

Quantum mechanics deals mainly with probabilities. A particle has a quantum state with probabilities for physical properties such as position, momentum, energy and angular momentum. The uncertainty principle outlines the theoretical limit of knowing how close you can measure any of these properties. The creation of quantum mechanics earned Heisenberg the 1932 Nobel Prize in Physics.

Notable Science Events for December 5

1965 – Joseph Erlanger died.

Joseph Erlanger
Joseph Erlanger (1874 – 1965)
Nobel Foundation

Erlanger was an American physiologist who shares the 1944 Nobel Prize in Medicine with Herbert Spencer Gasser for their research into the action potentials in nerve fibers. Action potentials are self-generating electrochemical pulse that allow nerve cells to transmit a signal over a distance. They discovered there were different fibers in nerves that had three different fibers that would conduct the potential from a stimulus at different rates. This led to the theory that one type of fiber conducts pain signals and others conduct motor control signals.

1932 – Sheldon Lee Glashow was born.

Glashow is an American physicist who shares the 1979 Nobel Prize in Physics with Abdus Salam and Steven Weinberg for their contributions to electroweak theory. The electroweak theory was formed to unify the forces of electromagnetism and the weak nuclear forces associated with radioactivity. Salam and Weinberg outlined a theory that could only be applied to leptons, but Glashow discovered a way to expand the theory to expand the theory to include other elementary particles by inventing a new property for quarks called ‘charm’.

1903 – Cecil Frank Powell was born.

Cecil Frank Powell (1903 - 1969)
Cecil Frank Powell (1903 – 1969)
Nobel Foundation

Powell was a British physicist who was awarded the 1950 Nobel Prize in Physics for the development of the photographic nuclear emulsion plate technique of studying nuclear processes and the discovery of the pi meson or pion. Pions are a class of mesons that help explain the strong nuclear force in particle physics.

1902 – Johannes Wislicenus died.

Wislicenus Johannes
Wislicenus Johannes (1835 – 1902)

Wislicenus was a German organic chemist who demonstrated the importance of spatial arrangement of atoms in a molecule. He explained the phenomena where two substances could have the same chemical formula but different chemical properties. The principle he called “geometric isomerism” was the beginnings of stereochemistry.

1901 – Werner Heisenberg was born.

1896 – Carl Ferdinand Cori was born.

Carl Ferdinand Cori
Carl Ferdinand Cori (1896 – 1984)
Nobel Foundation

Cori was an Austrian-American biochemist who shares half the 1947 Nobel Prize in Medicine with his wife, Gerty Theresa Cori, for discovering how the body metabolizes of glycogen. Glycogen is a molecule that is a starch derivative of glucose and an important part of the way the body stores food energy.

1892 – Carl Richard Moore was born.

Moore was an American zoologist who was the first to isolate the male sex hormones androsterone and testosterone. Androsterone was found to influence the growth and development of the reproductive system. Testosterone is responsible for initiating and maintaining secondary male sex characteristics.

1868 – Arnold Sommerfeld was born.

Arnold Sommerfeld
Arnold Sommerfeld (1868 – 1951)

Sommerfeld was a German physicist who introduced the fine-structure constant to quantum physics. He was trying to explain the hyperfine bands in the hydrogen spectrum using Bohr’s model of the hydrogen atoms. The fine-structure constant is a fundamental physical constant that appears in many fundamental quantum mechanics expressions and formulas.