Christiaan Huygens was born on 14 April 1629 in The Hague, into a rich and influential Dutch family,[3][4] the second son of Constantijn Huygens. Christiaan was named after his paternal grandfather.[5][6] His mother was Suzanna van Baerle. She died in 1637, shortly after the birth of Huygens' sister.[7] The couple had five children: Constantijn (1628), Christiaan (1629), Lodewijk (1631), Philips (1632) and Suzanna (1637).[8]

Constantijn Huygens was a diplomat and advisor to the House of Orange, and also a poet and musician. His friends included Galileo Galilei, Marin Mersenne and René Descartes.[9] Huygens was educated at home until turning sixteen years old. He liked to play with miniatures of mills and other machines. His father gave him a liberal education: he studied languages and music, history and geography, mathematics, logic and rhetoric, but also dancing, fencing and horse riding.[5][8][10]

In 1644 Huygens had as his mathematical tutor Jan Jansz de Jonge Stampioen, who set the 15-year-old a demanding reading list on contemporary science.[11] Descartes was impressed by his skills in geometry.[4]


In science, Christian Huygens (1629-1695) was a Dutch physicist noted for his 1669 determination that the quantity of the mass of an object multiplied by its velocity squared mv² remains constant during perfectly elastic collisions, such as between steel balls, and for his 1674 work with French physicist Denis Papin on vacuum pumps. Huygens’ quantity was later called vis viva by German mathematician Gottfried Leibniz in 1886. [1]

Education
Huygens was the well-traveled son of a rich and prominent Dutch family, that had entertained Rene Descartes. Huygens studied mathematics and law at the University of Leiden, spent time at Paris and London, where he met Isaac Newton, among other important people, and thereafter soon became an avid experimenter. In 1655, prior to developing skills as a lens-grinder, he and his brother built a telescope and discovered Titan and the rings of Saturn. [4]

Wave theory of light
Huygens lens grinding work led him into an investigation as to how lens work, research that resulted in several published papers on light.

In 1677, he observed how Iceland spar spit light into two parts, rotated through different degrees.

In 1678 paper communicated to France's Royal Academy of Sciences, in which he suggested that light is a series of shock waves, spreading in wave fronts generated by impacting light particles and making waves among the tiny particles of the ether, the invisible substance permeating the universe. [4] This is now known as the wave theory of light. In his 1690 Treatise on Light, he summarized: [3]

“I have thus shown in what manner one can imagine that light propagates successively by spherical waves.”

The later theory of light by Isaac Newton in his Opticks (1704) proposed a different explanation for reflection, refraction, and interference of light assuming the existence of light particles. The double slit interference experiments of Thomas Young vindicated Huygens' wave theory in 1801, as the results could no longer be explained with light particles; these two views, following the invention of the light quanta (photon), resulted to yield the wave-particle duality model.

Vacuum pump
In circa 1645, German engineer Otto Guericke invented a vacuum pump to disprove Greek philosopher Parmenides' circa 485 BC hypothesis that “nature abhorred a vacuum”. The invention was described in the 1657 book Mechanical Hydraulic Pneumatics by German scientist Gaspar Schott, a correspondent of Guericke. [2] Among those to have read the book were Huygens and his associate Irish physicist Robert Boyle, who each built or acquired pumps of their own.

Some time prior to 1674, French physicist Denis Papin moved to Paris and assisted Huygens in his experiments with the air-pump and gunpowder piston and cylinder engines, the results of which Experiences of the Void (Experiences du Vuide) were published at Paris in that year, and also in the form of five papers by Huygens and Papin jointly, in the Philosophical Transactions for 1675. This association was a precursor to Papin’s later invention of the first steam engine in 1690