April 18 marks the passing of one of the most influential scientists of the 20th Century, Albert Einstein.
Einstein started his career as a technical assistant at a Swiss Patent office in 1901. While working there, he obtained his Doctorate and published four papers on the photoelectric effect, Brownian motion, special relativity, and the equivalence of mass and energy. These papers earned him international recognition at the age of 25.
The paper on the photoelectric effect where light shining on a material can produce electrons emitted from the surface introduced the concept of the photon. A photon is a packet of light waves with energy equal to Planck’s constant times the frequency of the light. These discrete packets of light helped usher in the idea the quanta of quantum mechanics. His work on this topic earned him the 1921 Nobel Prize in Physics.
Einstein’s Brownian motion paper was an attempt to describe the randomized action of individual particles in a liquid. He used statistical mechanics to describe the motion was due to collisions and diffusion of individual particles within the liquid. This was important to combine Newtonian physics, thermodynamics, and chemistry into kinetic theory. He would refine this paper in a few years where the French physicist Jean Baptiste Perrin would provide experimental evidence to verify Einstein’s theories.
Einstein’s special relativity paper blended Maxwell’s electricity and magnetism equations with ideas how mechanics change as speeds approach the speed of light. This paper had two important axioms. The first was the laws of nature work the same for all observers that move with constant speed relative to each other. The second was the speed of light is fixed and the same for any frame of reference. This would later be refined into his general theory of relativity which said all observers are equivalent.
The mass-energy equivalence paper gave us probably the most famous equation: E = mc2. The energy of a body at rest is equal to its mass times the speed of light squared. This helped explain the energy released or consumed in nuclear reactions such as fission or fusion.
He continued to produce new ideas such as the idea that gravity could bend light which was verified during the 1919 solar eclipse where the Sun’s gravity deflected light from distant stars. This idea was the first major change in the idea of gravity since Newton’s equation.
Early in World War II, the German government seized his home while he was away on a lecture tour. He wisely decided to spend the rest of the war in the United States. He was not asked to take part in the Manhattan Project to build the atomic bomb since he had Swiss citizenship, but he had a significant part in the formation of the project. He and Leo Szilard sent President Roosevelt a letter urging the research into atomic fission. While initially, the US Government barely acknowledged the research, it quickly grew into the project that developed the atomic bomb.
After the war, Einstein was involved in the formation of the Jewish State, Israel. He was asked to become Israel’s first President. He declined in favor of biochemist Chaim Weizmann and instead spent the rest of his life trying to come up with a grand unifying theory of relativity. Einstein died in 1955 of an aortic aneurysm at age 76.
Element 99 was named einsteinium later that same year in his honor.
Notable Science History Events for April 18
1955 – Albert Einstein died.
1945 – John Ambrose Fleming died.
Fleming was an English electrical engineer who was the inventor of the thermionic valve vacuum tube as an electronic device. The device functioned as a diode used as a rectifier to convert AC current into DC current. Fleming’s diodes were used in early radio receivers and radar systems before the invention of solid-state semiconductors.
He was also the originator of the familiar “right-hand rule” salute used by mathematicians and physicists to determine the direction of vectors that are multiplied together. You take your flat right hand and point the fingers towards the first vector, close your fingers towards the second vector and the direction your thumb points to the resulting direction. Go to any electricity and magnetism classroom and watch the number of students performing this salute and think of John Ambrose Fleming.
1940 – Joseph L. Goldstein was born.
Goldstein is an American biochemist who shares the 1985 Nobel Prize in Medicine with Michael Brown for their discoveries on how cholesterol metabolism is regulated. They found that cells remove cholesterol from the bloodstream by low-density lipoproteins.
This discovery would lead to the statin drugs to lower cholesterol used by many people today.
1911 – Maurice Goldhaber was born.
Goldhaber was an Austrian-American experimental physicist who made many contributions to nuclear physics. He established the first accurate measurement of the newly discovered neutron in 1934 and provided evidence it was it’s own particle and not a compound of positrons and electrons. He also showed beta radiation was the same as atomic electrons. He worked with Edward Teller to develop concepts leading to giant dipole resonance and worked with Lee Grodzins and Andrew Sunyar to establish the negative helicity of neutrinos.
1908 – George H. Hitchings was born.
Hitchings was an American doctor spent a career developing drug treatments for a myriad of diseases. His team developed drug therapies for malaria, leukemia, gout, organ transplant rejection, herpes, and AIDS. His work with chemotherapy earned him part of the 1988 Nobel Prize in Medicine with James Black and Gertrude Elion.
1892 – Eugene Houdry was born.
Houndry was a French engineer who invented the Houndry process of catalytic cracking of petroleum to gasoline. The Houndry process is still in use in refineries today.
He also invented the catalytic converter in an attempt to reduce the amount pollutants caused by automotive combustion. This device was never used in cars until gasoline stopped using tetraethyl lead additives. The lead additive would destroy the catalyst rendering the device useless. Today, they’re standard equipment in automobiles.
1838 – Paul Émile Lecoq de Boisbaudran was born.
Lecoq was a French chemist who used Kirchhoff’s spectroscopy techniques to discover the elements gallium, samarium, and dysprosium.
Lecoq found the first of Mendeleev’s predicted elements, eka-aluminum. He named this element gallium. Some believed he named this element after himself since “gallus” is Latin for “le coq” (rooster). He later tried to clarify in an article the name came from the Latin name of Gaul: Gallus.
He found evidence of another element in his samples of samarium and gadolinium, but could never isolate the hidden element. French chemist Eugène-Anatole Demarçay would use this data to eventually discover the element europium.