Carl Edward Sagan (November 9, 1934 – December 20, 1996) was an American astronomer, astrophysicist, author, cosmologist, and highly successful popularizer of astronomy, astrophysics and other natural sciences. During his lifetime, he published more than 600 scientific papers and popular articles and was author, co-author, or editor of more than 20 books. In his works, he advocated skeptical inquiry and the scientific method. He pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence (SETI).

Sagan became world-famous for his popular science books and for the award-winning 1980 television series Cosmos: A Personal Voyage, which he narrated and co-wrote. A book to accompany the program was also published. Sagan also wrote the novel Contact, the basis for the 1997 film of the same name.

Clinton Richard Dawkins, FRS, FRSL (born 26 March 1941) is a British ethologist, evolutionary biologist and popular science author. He was formerly Professor for Public Understanding of Science at Oxford and was a fellow of New College, Oxford.

Dawkins came to prominence with his 1976 book The Selfish Gene, which popularised the gene-centred view of evolution and introduced the term meme. In 1982, he introduced into evolutionary biology an influential concept, presented in his book The Extended Phenotype, that the phenotypic effects of a gene are not necessarily limited to an organism's body, but can stretch far into the environment, including the bodies of other organisms.

Dawkins is well known for his straightforward criticism of creationism and intelligent design. In his 1986 book The Blind Watchmaker, he argued against the watchmaker analogy, an argument for the existence of a supernatural creator based upon the complexity of living organisms. Instead, he described evolutionary processes as analogous to a blind watchmaker. He has since written several popular science books, and makes regular television and radio appearances, predominantly discussing these topics.

Dawkins is an atheist, secular humanist, skeptic, rationalist and supporter of the Brights movement. He has been referred to in the media as "Darwin's Rottweiler", by analogy with English biologist T. H. Huxley, who was known as "Darwin's Bulldog" for his advocacy of Charles Darwin's evolutionary ideas. In his 2006 book The God Delusion, Dawkins contends that a supernatural creator almost certainly does not exist and that faith qualifies as a delusion ? as a fixed false belief. As of January 2010, the English language version had sold more than 2 million copies and had been translated into 31 other languages, making it his most popular book to date.

Neil deGrasse Tyson (born October 5, 1958) is an American astrophysicist, and the Frederick P. Rose Director of the Hayden Planetarium at the Rose Center for Earth and Space, and a Research Associate in the Department of Astrophysics at the American Museum of Natural History in Manhattan. Since 2006, he has hosted PBS's educational television show NOVA scienceNOW. He has been a frequent guest on The Daily Show, The Colbert Report, and Jeopardy!.

Richard Phillips Feynman , May 11, 1918 – February 15, 1988) was an American physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics (he proposed the parton model). For his contributions to the development of quantum electrodynamics, Feynman, jointly with Julian Schwinger and Sin-Itiro Tomonaga, received the Nobel Prize in Physics in 1965. He developed a widely used pictorial representation scheme for the mathematical expressions governing the behavior of subatomic particles, which later became known as Feynman diagrams. During his lifetime, Feynman became one of the best-known scientists in the world.

Galileo Galilei 15 February 1564 – 8 January 1642) was an Italian physicist, mathematician, astronomer and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations, and support for Copernicanism. Galileo has been called the "father of modern observational astronomy,"[ the "father of modern physics," the "father of science," and "the Father of Modern Science." Stephen Hawking says, "Galileo, perhaps more than any other single person, was responsible for the birth of modern science."

Quantum mechanics (QM), also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic scales. In advanced topics of QM, some of these behaviors are macroscopic and only emerge at very low or very high energies or temperatures. The name, coined by Max Planck, derives from the observation that some physical quantities can be changed only by discrete amounts, or quanta, as multiples of the Planck constant, rather than being capable of varying continuously or by any arbitrary amount. For example, the angular momentum, or more generally the action, of an electron bound into an atom or molecule is quantized. While an unbound electron does not exhibit quantized energy levels, an electron bound in an atomic orbital has quantized values of angular momentum. In the context of QM, the wave–particle duality of energy and matter and the uncertainty principle provide a unified view of the behavior of photons, electrons and other atomic-scale objects.

The Royal Library of Alexandria, or Ancient Library of Alexandria, in Alexandria, Egypt, was the largest and most significant great library of the ancient world. It flourished under the patronage of the Ptolemaic dynasty and functioned as a major center of scholarship from its construction in the third century B.C.E. until the Roman conquest of Egypt in 48 B.C.E. In Roman times, scholars used a related library called the Serapeum, located in another part of the city. This library was described as the "daughter library" and was also a temple to the god Serapis.

Stephen William Hawking, CH, CBE, FRS, FRSA (born 8 January 1942) is a British theoretical physicist and cosmologist, whose scientific career spans over forty years. His books and public appearances have made him an academic celebrity and he is an Honorary Fellow of the Royal Society of Arts, a lifetime member of the Pontifical Academy of Sciences, and in 2009 was awarded the Presidential Medal of Freedom, the highest civilian award in the United States.

Probability theory is the branch of mathematics concerned with analysis of random phenomena. The central objects of probability theory are random variables, stochastic processes, and events: mathematical abstractions of non-deterministic events or measured quantities that may either be single occurrences or evolve over time in an apparently random fashion. Although an individual coin toss or the roll of a die is a random event, if repeated many times the sequence of random events will exhibit certain statistical patterns, which can be studied and predicted. Two representative mathematical results describing such patterns are the law of large numbers and the central limit theorem.

As a mathematical foundation for statistics, probability theory is essential to many human activities that involve quantitative analysis of large sets of data. Methods of probability theory also apply to descriptions of complex systems given only partial knowledge of their state, as in statistical mechanics. A great discovery of twentieth century physics was the probabilistic nature of physical phenomena at atomic scales, described in quantum mechanics.

William Sanford "Bill" Nye (born November 27, 1955), popularly known as "Bill Nye the Science Guy", is an American science educator, comedian, television host and mechanical engineer. He is best known as the host of the Disney children's science show Bill Nye the Science Guy (1993–1998) and for his many subsequent appearances in popular media as a science educator.

Richard Phillips Feynman , May 11, 1918 – February 15, 1988) was an American physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics (he proposed the parton model). For his contributions to the development of quantum electrodynamics, Feynman, jointly with Julian Schwinger and Sin-Itiro Tomonaga, received the Nobel Prize in Physics in 1965. He developed a widely used pictorial representation scheme for the mathematical expressions governing the behavior of subatomic particles, which later became known as Feynman diagrams. During his lifetime, Feynman became one of the best-known scientists in the world.