American Scientists Series Slideshow

Barbara McClintock (1902-1992) conducted maize plant research that led to her discovery of genetic transposition — the movement of genetic material within and between chromosomes. In 1983, this pioneering geneticist was awarded the Nobel Prize in Physiology or Medicine.

Josiah Willard Gibbs (1839-1903) formulated the modern system of thermodynamic analysis. For this and other extraordinary achievements, Gibbs received some of the most prestigious awards of his era, including the Rumford Prize from the American Academy of Arts and Sciences.

John von Neumann (1903-1957) made significant contributions in both pure and applied mathematics, especially in the areas of quantum mechanics, game theory, and computer theory and design. In 1956, the U.S. government presented the Enrico Fermi Award to this eminent mathematician.

Richard P. Feynman (1918-1988) developed a new formulation of quantum theory based, in part, on diagrams he invented to help him visualize the dynamics of atomic particles. In 1965, this noted theoretical physicist, enthusiastic educator, and amateur artist was awarded the Nobel Prize in Physics.

Biochemist Gerty Cori (1896-1957), in collaboration with her husband, Carl, made important discoveries — including a new derivative of glucose — that elucidated the steps of carbohydrate metabolism and contributed to the understanding and treatment of diabetes and other metabolic diseases. In 1947, the couple was awarded a half share of the Nobel Prize in Physiology or Medicine.

A remarkably versatile scientist, structural chemist Linus Pauling (1901-1994) won the 1954 Nobel Prize in Chemistry for determining the nature of the chemical bond linking atoms into molecules. His work on protein structure was critical in establishing the field of molecular biology; his studies of hemoglobin led to the classification of sickle cell anemia as a molecular disease.

Often called a “pioneer of the distant stars,” astronomer Edwin Hubble (1889-1953) played a pivotal role in deciphering the vast and complex nature of the universe. His meticulous studies of spiral nebulae proved the existence of galaxies other than our own Milky Way. Had he not died suddenly in 1953, Hubble would have won that year’s Nobel Prize in Physics.

Theoretical physicist John Bardeen (1908-1991) shared the Nobel Prize in Physics twice — in 1956, as co-inventor of the transistor and in 1972, for the explanation of superconductivity. The transistor paved the way for all modern electronics, from computers to microchips. Diverse applications of superconductivity currently include infrared sensors and medical imaging systems.

Melvin Calvin (1911-1997) advanced our understanding of photosynthesis and conducted pioneering research on using plants as an alternative energy source. He won the Nobel Prize in chemistry in 1961. The stamp art includes a photograph of him taken by Yousuf Karsh. The background shows excerpts from the carbon cycle, and chemical symbols and structures he used to represent the process of photosynthesis.

Asa Gray (1810-1888), one of the nation’s first professional botanists, advanced the specialized field of plant geography and became the principal American advocate of evolutionary theory in the mid-nineteenth century. The stamp art features illustrations of plants studied by Gray and the words “Shortia galacifolia” in Gray’s handwriting.

Maria Goeppert Mayer (1906-1972) developed a theoretical model that helped explain the structure of the atomic nucleus; for this work she became the only woman other than Marie Curie to win a Nobel Prize in physics. The stamp art combines photographs of Mayer with a chart and a diagram she used to illustrate aspects of the atomic nucleus.

Severo Ochoa (1905-1993), a biochemist, was the first scientist to synthesize ribonucleic acid (RNA) and competed in the race to decipher the genetic code. He won the Nobel Prize in physiology or medicine in 1959. The stamp shows Ochoa in his laboratory in 1959, along with figures representing some of his work on protein synthesis.