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Sir Isaac Newton (1642-1727)

An English mathematician, physicist, alchemist, and theologian. The founder of contemporary physics and mathematical analysis, as well as of the methodology of experimental sciences (he formulated, among others, the four principles of scientific method). He formulated the three celebrated laws of motion and derived the law of universal gravitation, contributed to the development of optics and spectral analysis (by splitting white light). He developed the calculus (in parallel and independently of Leibniz) and laid the foundations for the calculus of variations. His laws of motion and the law of universal gravitation allowed him to explain Kepler's laws of planetary motion, which constituted an ultimate confirmation of the heliocentric system of Copernicus. Newton was involved in many disputes regarding the priority of scientific discoveries. This was in part because he used to publish his discoveries reluctantly and with considerable delay.

His fundamental works were, among others:

1669-1671:

Designed and built the first reflecting telescope (Newtonian telescope).

1687:

His fundamental work "Philosophiae Naturalis Principia Mathematica" ("Mathematical Principles of Natural Philosophy"), has been published many years after the discovery of most of the results described in it. The book included, among others:

• The three laws of motion, in more modern formulation:
  • The First Law (the inertia principle): If no net force acts on an object, then it will stay at rest, or in uniform motion along a straight line.
  • The Second Law (the principle of acceleration): F = m·a, that is the change of motion (acceleration a) of an object is proportional to the magnitude of the force (F) acting on it, and inversely proportional to its mass (m).
  • The Third Law (the principle of acion and reaction): To each action corresponds and equal reaction in the opposite direction.
• The law of universal gravitation (which he derived using Kepler's third law), expressed by:

  F = G·m₁·m₂ / r²,

  where:

  G = 6.673·10^-11 Nm²/kg² - the gravitational constant,

  F - the force of gravitational attraction,

  m₁, m₂ - the masses of attracting bodies;

  r - the distance of centers of gravity of these bodies.

• An application of those laws to explanation of, among others, the mechanism of tides, the details of the motion of the Moon  (taking into account gravitational perturbations caused by the Sun), the shape of the Earth  (an ellipsoid flattened at the poles), precession of Earth's  rotational axis, and the motion of planets and comets.

1704:

Published the work "Opticks..." ("Optics..."), in which he summarized his discoveries in the field of splitting white light with a prism (this led to a subsequent creation of spectral analysis allowing, among others, to determine the chemical composition of distant astronomical objects), gave a detailed description of a corpuscular theory of light and described optical phenomena in thin layers (among others, the so-called "Newtonian rings").

Named after Newton were:

• a large crater (78 km diameter) on the near side of the Moon ,
• one of the largest craters (287 km diameter) on Mars ,
• asteroids 662 Newtonia and 8000 Isaac Newton.

[ZK]

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