Michael H. Hart (born April 28, 1932 in New York City) is an astrophysicist who has also written three books on history and controversial articles on a variety of subjects. Hart describes himself as a Jeffersonian liberal, while his critics call him a conservative and a racial separatist.

Hart, a graduate of the Bronx High School of Science who enlisted in the U.S. Army during the Korean War, received his undergraduate degree at Cornell University in mathematics and later earned a Ph.D. in astrophysics at Princeton University. He also holds graduate degrees in physics, astronomy, and computer science, as well as a law degree. He was a research scientist at NASA before leaving to be a professor of physics at Trinity University in San Antonio, Texas. He has also taught both astronomy and history of science at Anne Arundel Community College in Arnold, Maryland. His published work in peer-reviewed scientific journals includes several detailed computer simulations of atmospheric evolution.

Among Hart's articles was one, published in 1975, that gave scientific support for the conclusion that the only intelligent life in the Milky Way Galaxy resides on the planet Earth.

The 100: A Ranking of the Most Influential Persons in History is a 1978 book by Michael H. Hart, reprinted in 1992 with revisions. It is a ranking of the 100 people who, according to Hart, most influenced human history.

The first person on Hart's list is the Prophet of Islam Muhammad. Hart asserted that Muhammad was "supremely successful" in both the religious and secular realms. He also believed that Muhammad's role in the development of Islam was far more influential than Jesus' collaboration in the development of Christianity. He attributes the development of Christianity to St. Paul, who played a pivotal role in its dissemination."

The 1992 revisions included the demotion of figures associated with Communism, such as Vladimir Lenin and Mao Zedong, and the introduction of Mikhail Gorbachev. Hart took sides in the Shakespearean authorship issue and substituted Edward de Vere, 17th Earl of Oxford for William Shakespeare. Hart also substituted Niels Bohr and Henri Becquerel with Ernest Rutherford, thus correcting an error in the first edition. Henry Ford was also promoted from the "Honorary Mentions" list, replacing Pablo Picasso. Finally, some of the rankings were re-ordered, although no one listed in the top ten changed position.

Ice cubes are small, roughly cube-shaped pieces of ice, conventionally used to cool beverages. Ice cubes are sometimes preferred over crushed ice because they melt more slowly; they are standard in mixed drinks that call for ice, in which case the drink is said to be "on the rocks."

Ice cubes that are crushed or sheared into irregularly-shaped flakes may add an interesting aesthetic effect to some cocktails. Crushed ice is also used when faster cooling is desired, since the rate of cooling is governed by the number and average radius of the ice particles.

Melting ice cubes sometimes precipitate white flakes, commonly known as "floaties". This is calcium carbonate which is present in many water supplies and is completely harmless.^{[citation needed]}

American physician and humanitarian John Gorrie built a refrigerator in 1844 with the purpose of cooling air. His refrigerator produced ice which he hung from the ceiling in a basin. Gorrie can be considered the creator of ice cubes, but his aim was not to cool drinks: he used the ice to lower the ambient room temperature. During his time, a dominant idea was that bad air quality caused disease. Therefore, in order to help treat sickness, he pushed for the draining of swamps and the cooling of sickrooms.