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From Encarta:
Galileo (1564-1642), Italian physicist and astronomer, who, with the German astronomer Johannes Kepler, initiated the scientific revolution that flowered in the work of the English physicist Sir Isaac Newton. Born Galileo Galilei, his main contributions were, in astronomy, the use of the telescope in observation and the discovery of sunspots, lunar mountains and valleys, the four largest satellites of Jupiter, and the phases of Venus. In physics, he discovered the laws of falling bodies and the motions of projectiles. In the history of culture, Galileo stands as a symbol of the battle against authority for freedom of inquiry.

For more information, look at The Galileo Project at Rice University

From Encarta:

   Two important developments in pure geometry occurred during the century. The first was the publication, in Discourse on Method (1637) by Descartes, of his discovery of analytic geometry, which showed how to use the algebra that had developed since the Renaissance to investigate the geometry of curves. (Fermat made the same discovery but did not publish it.) This book, together with short treatises that had been published with it, stimulated and provided the basis for Isaac Newton's mathematical work in the 1660s. The second development in geometry was the publication by the French engineer Gérard Desargues in 1639 of his discovery of projective geometry. Although the work was much appreciated by Descartes and the French philosopher and scientist Blaise Pascal, its eccentric terminology and the excitement of the earlier publication of analytic geometry delayed the development of its ideas until the early 19th century and the works of the French mathematician Jean Victor Poncelet.

For more information, look at this article from the School of Mathematics and Statistics, University of St Andrews, Scotland


From Encarta:
    English physicist and mathematician, who was the culminating figure
of the scientific revolution of the 17th century. In optics, his discovery
of the composition of white light integrated the phenomena of
colours into the science of light and laid the foundation for modern
physical optics. In mechanics, his three laws of motion, the basic
principles of modern physics, resulted in the formulation of the law of
universal gravitation. In mathematics, he was the original discoverer
of the infinitesimal calculus. Newton's Philosophiae Naturalis Principia
Mathematica (Mathematical Principles of Natural Philosophy), 1687, was
one of the most important single works in the history of modern

For more information, look at this site:

James Clerk Maxwell:

From Encarta:

    Scottish physicist best known for his formulation of electromagnetic theory. He is
regarded by most modern physicists as the scientist of the 19th century who had the
greatest influence on 20th-century physics, and he is ranked with Sir Isaac Newton
and Albert Einstein for the fundamental nature of his contributions. In 1931, on the
100th anniversary of Maxwell's birth, Einstein described the change in the conception
of reality in physics that resulted from Maxwell's work as "the most profound and the
most fruitful that physics has experienced since the time of Newton."

For more information look here:

Special Theory of Relativity:

From Encarta:

    In 1905, Einstein published the first of two important papers on the theory of relativity, in which he dismissed the problem of absolute motion by denying its existence. According to Einstein, no particular object in the universe is suitable as an absolute frame of reference that is at rest with respect to space. Any object (such as the center of the solar system) is a suitable frame of reference, and the motion of any object can be referred to that frame.

    Einstein stated the relative rate of motion between any observer and any ray of light is always the same, 300,000 km/sec (186,000 mi/sec), and thus two observers, moving relative to one another even at a speed of 160,000 km/sec (100,000 mi/sec), each measuring the velocity of the same ray of light, would both find it to be moving at 300,000 km/sec (186,000 mi/sec), and this apparently anomalous result was proved by the Michelson-Morley experiment.

See more on a website at SLAC

and from a text by Einstein himself:



    Ether or aether, in physics and astronomy, a hypothetical medium for transmitting light and heat (radiation), filling all unoccupied space; it is also called luminiferous ether. In Newtonian physics all waves are propagated through a medium, e.g., water waves through water, sound waves through air. When James Clerk Maxwell developed his electromagnetic theory of light, Newtonian physicists postulated ether as the medium that transmitted electromagnetic waves. Ether was held to be invisible, without odor, and of such a nature that it did not interfere with the motions of bodies through space. The concept was intended to connect the Newtonian mechanistic wave theory with Maxwell's field theory. However, all attempts to demonstrate its existence, most notably the Michelson-Morley experiment of 1887, produced negative results and stimulated a vigorous debate among physicists that was not ended until the special theory of relativity, proposed by Albert Einstein in 1905, became accepted. The theory of relativity eliminated the need for a light-transmitting medium, so that today the term ether is used only in a historical context.

Joule, James Prescott:

From the

    English physicist. His scientific researches began in his youth when he invented an electromagnetic engine. Joule made valuable contributions to the fields of heat, electricity, and thermodynamics. His work established the mechanical theory of heat, and he was the first to determine the relationship between heat energy and mechanical energy (the mechanical equivalent of heat). Joule discovered the first law of thermodynamics, which is a form of the law of conservation of energy (see conservation laws). He was one of the great experimental scientists of the 19th cent. The mechanical unit of work is named for him.

Helmholtz, Hermann:


1821-94, German scientist. Although known especially as a physicist and biologist, he was also a physician, mathematician, philosopher, and lecturer on popular science. He extended the application of the law of conservation of energy and in 1847 formulated it mathematically. He contributed to the knowledge of thermodynamics and electrodynamics and studied vortex motion in fluids.

Fahrenheit, Gabriel:

From the Encyclopedia Britannica:

German physicist and maker of scientific instruments. He is best known for inventing the alcohol thermometer (1709) and mercury thermometer (1714) and for developing the Fahrenheit temperature scale; this scale is still commonly used in the United States.

Celsius, Anders:

From the Encyclopedia Britannica:

astronomer who invented the Celsius thermometer scale (often called centigrade scale).

Steam Engines:

From the Encyclopedia Britannica:

Sadi Carnot:

From the Encyclopedia Britannica:

MARIE-FRANÇOIS-SADI CARNOT, an engineer turned statesman who served as fourth president (1887-94) of the Third Republic until he was assassinated by an Italian anarchist.

Clausius, Rudolph:

From the Encyclopedia Britannica:

German mathematical physicist who formulated the second law of thermodynamics and is credited with making thermodynamics a science

Young, Thomas

From the Encyclopedia Britannica:

English physician and physicist who established the principle of interference of light and thus resurrected the century-old wave theory of light.

Faraday, Michael

Faraday, trained as a bookbinder, was hired to work in the laboratories of Sir Henry Davy. With little background in mathematics, Faraday was still able to make monumental contributions to the fields electricity and magnetism. He noted (as did Joseph Henry in the United States and H. Lenz in Russia almost simultaneously) that a changing current in one coil of wire caused a current to flow in a nearby wire. The connecting effect was the magnetic field produced by the current in the first wire (discovered earlier by Ampere). Further, he noted that if a wire were to be caused to move in the presence of a magnetic field produced by a permanent magnet, a current would be induced in the wire.  From this he made the first electric generator, thus allowing electricity to be made for the first time without the need for batteries or frictional methods

From the Encyclopedia Britannica: