Isaac Newton (4.01.1643-31.03.1727) was an outstanding English scientist who laid the foundations of modern natural science, the creator of classical physics, a Fellow of the Royal Society (1672) and its president (from 1703). He was born in Woolsthorpe. He graduated from the University of Cambridge (1665). In 1669—1701 he held a chair there. From 1695 he was warden, and from 1699 director, of the Mint.
His work was in mechanics, optics, astronomy and mathematics. He formulated the basic laws of classical mechanics, discovered the law of universal gravitation and the dispersion of light, extended the corpuscular theory of light, and developed (independently of G. Leibniz) differential and integral calculus. Generalising the results of the research of his predecessors in mechanics and his own, he created a monumental work, the “Mathematical Principles of Natural Philosophy” (the “Principia”), published in 1687. The “Principia” contained the basic concepts and the axiomatics of classical mechanics, in particular the concepts of mass (to which Newton attached great importance as the basic one in mechanical processes), quantity of motion, force, acceleration and centripetal force, and the three laws of motion (Newton's laws): the law of inertia, the law of proportionality of force to acceleration, and the law of action and reaction. His law of universal gravitation is given there too, and from it Newton explained the motion of the celestial bodies (the planets, their satellites and comets) and created the theory of gravitation. The discovery of this law marked the transition from a kinematic description of the solar system to a dynamic explanation of phenomena and finally confirmed the victory of the teaching of Copernicus. He showed that Kepler's three laws follow from the law of universal gravitation; he explained the peculiarities of the motion of the Moon and the phenomenon of precession; he developed the theory of the figure of the Earth, noting that it must be flattened at the poles, and the theory of the tides; he considered the problem of creating an artificial satellite of the Earth, and so on. He established the law of resistance and the basic law of internal friction in liquids and gases, and gave a formula for the speed of propagation of waves.
He created a physical picture of the world that dominated science for a long time (the Newtonian theory of space and time). He regarded space and time as absolute, postulating this in his “Principia”. Closely connected with this understanding of space and time is his idea of action at a distance: the instantaneous transmission of action from one body to another across empty space without the aid of matter. Newton's theory of action at a distance and his scheme of the world dominated until the beginning of the 20th century. Its limitations were first detected by M. Faraday and J. Maxwell, who showed that it does not apply to electromagnetic phenomena, and the theory of relativity, which arose at the beginning of the 20th century, finally proved the limitations of Newton's classical physics, the physics of low velocities and macroscopic scales. However, special relativity did not discard the laws established by Newton's classical mechanics altogether, but only refined and supplemented them for the case of motion at velocities comparable with the speed of light in vacuum. “Today the place of Newton's scheme of forces acting at a distance, wrote A. Einstein, has been taken by field theory, and its laws too have undergone changes, but everything that has been created since Newton is a further organic development of his ideas and methods.”
Newton's contribution to optics is great. In 1666, with the help of a triangular glass prism, he split white light into seven colours (a spectrum), thereby proving its complexity (the phenomenon of dispersion), and discovered chromatic aberration. Trying to avoid aberration in telescopes, in 1668 and in 1671 he constructed a reflecting telescope of an original design, a mirror (reflecting) one in which a concave spherical mirror was used instead of a lens (the Newtonian telescope). He studied the interference and diffraction of light, investigating the colours of thin plates, discovered the so-called Newton's rings, established regularities in their arrangement, and expressed the idea of the periodicity of the light process. He tried to explain double refraction and came close to discovering the phenomenon of polarisation. He considered light to be a stream of corpuscles, which is Newton's corpuscular theory of light (although at different stages he considered the possibility of wave properties of light as well, and in 1675 in particular he made an attempt to create a compromise corpuscular-wave theory of light). He set out his optical research in the “Opticks” (1704).
In his world view Newton was a spontaneous materialist, the second great representative of mechanistic materialism in natural science, after R. Descartes, in the 17th and 18th centuries.
Newton's scientific work played an exceptionally important role in the history of the development of physics. In the words of A. Einstein, “Newton was the first to try to formulate elementary laws which determine the course in time of a wide class of processes in nature with a high degree of completeness and accuracy,” and “... through his work he exerted a deep and powerful influence on the whole world view.”
The unit of force in the International System of Units, the newton, is named in his honour. Member of the Paris Academy of Sciences (1699).