Though one of the most brilliant scientists in history, Christiaan Huygens enjoyed relatively little fame during his lifetime--primarily because he worked during the period directly after the death of Galileo and just before the ascent of Isaac Newton. Although his work went unregarded for many years after his death, he is today held as one of the chief contributors to the modern sciences of mechanics, physics, and astronomy.
Huygens was born in the Hague, Netherlands, in 1629. The environment in which he was raised was ideal for the nurturing of young minds: his father, Constantijn Huygens, was a diplomat and poet who understood the need for classical training, and he planned for his son a private education in mathematics, languages, literature, and music. Young Christiaan was also influenced by mathematician-philosopher René Descartes, a friend of the Huygens family and frequent visitor to their home. Huygens learned about the " mechanistic" philosophy of nature from Descartes and came to believe that all natural phenomena would one day be explained by science.
Huygens left his home in 1645 to study law and mathematics at the University of Leiden and, in 1647, he entered the College of Orange in Breda. He was dissatisfied with the university's approach to learning, however, and in 1649 he returned to the Hague. There he remained until 1666, living off an allowance from his wealthy father. Given the financial freedom to study as he pleased, Huygens began to perform some of his most important research. During the latter half of the seventeenth century, it was not unusual for a scientist to work in several different disciplines, attaining success in each. Such was the case with Huygens, who worked simultaneously in the fields of astronomy, physics, and applied mathematics.
In the early 1650s, Huygens spent much of his time learning to grind telescopelenses; though tutored by Dutch philosopher Baruch Spinoza (1632-1677), he was essentially self-taught in this art. By 1655 he had developed a new grinding technique that yielded lenses of unsurpassed clarity. Using his lenses, Huygens almost immediately discovered a large moon circling Saturn, which he named Titan. At this time there were six-known planets and six-known moons, and for a short time Huygens believed that, since this was such a convenient arrangement, no other heavenly bodies would be discovered.
In 1656 Huygens incorporated his lenses into telescopes of extreme length--some up to 23 feet (7 m)--whose long focal length allowed for even greater magnification. Using telescopes of such design Huygens was able to chart the surface features of the planet Mars, as well as discover the Great Orion nebula (a multicolored cloud of hot gas in the Orion constellation).
In that same year, Huygens discovered the truth about the "triple" planet Saturn--so named because it appeared in conventional telescopes to possess two smaller planets to either side. Using his vastly superior telescope Huygens found that Saturn was encircled within a thin ring. Huygens reported his discovery in a secret code, protecting it from other scientists while he continued his observations of Saturn.
To facilitate these observations, Huygens designed several new pieces of astronomical equipment. Chief among these were his lenses, which provided far greater resolution and magnification than any before. After several years he perfected an achromatic lens that corrected the "false color" fringes often associated with inferior lens systems; this lens, called the Huygensian eyepiece, is still used in many telescopes today.
In order to better view the sky, Huygens also modified the design of his telescopes. It was commonly known that longer telescopes, with their longer focal lengths, allowed for greater magnification. Huygens took this principle to its extremes, constructing telescopes up to 23 feet (7 m) long. While these remarkable instruments gave a magnificent view of the planets, Huygens remained unsatisfied: he believed that the conventional telescope design was too limiting, for it relied upon metal tubes that would bend if they were too long. His answer was a tubeless telescope called an aerial telescope. Because there was no tube to connect them, the large objective lens and the smaller eyepiece could be as far apart as practical lens construction would allow. The largest of these aerial telescopes was more than 100 feet (30 m) in length. In addition to optical aids, Huygens also invented a micrometer in 1658 that enabled him to measure the angular separations of objects (such as the apparent distance between Saturn and its moon) with a precision of a few seconds of arc.
While Huygens observed the heavens, the European scientific community was working toward the development of a reliable timekeeping device; such a device was in great demand by the trading industry, which required an accurate clock for use in the navigation of its sailing vessels. Previously, clocks were regulated by a slowly falling weight that would turn the device's gears. Unfortunately, the pace of the weight's descent was irregular, and the clocks were wildly inaccurate.
Years earlier, Galileo had noted that a pendulum would swing with a precise motion, taking the same amount of time to move in one direction as it did to return. He termed this effect isochronicity ("equal time") and suggested that it might be useful as a means for regulating timepieces; however, he was never successful in designing a working model.
In 1656 Huygens found that a swinging pendulum was not truly isochronic unless the arc it made was not quite circular. Using this knowledge he devised a system combining the pendulum with a weight-driven clock: the pendulum would swing exactly once each second, precisely regulating the motion of the clock's hands; the falling weight would drive the gears, as well as give the pendulum just enough energy to overcome the slowing forces of air resistance and friction. Before the invention of Huygens's pendulum clock there was no reliable means of measuring time. Within months of the introduction of the "grandfather clock" design, towns across the Netherlands (and, soon after, all of Europe) had large clock towers regulated by swinging pendulums.
As he experimented with pendulums, Huygens also noticed certain relationships between the mass of the weight and the velocity of its swing. From his observations he formulated a theory of momentum that was included in his 1673 publication Horologux Oscillatoriux; it is now better known as the law of conservation of momentum, wherein it is stated that the energy of a moving object remains constant until the object is stopped or its direction is changed. While the law of the conservation of momentum had been proposed earlier by John Wallis, Huygens's theory was expressed more clearly and completely. This law was eventually expanded into Hermann von Helmholtz's law of the conservation of energy, which was later expanded by Albert Einstein to include the special theory of relativity. Huygens also proposed hypotheses on centrifugal force, as well as the value for the acceleration of a falling body (g).
Meanwhile, a debate was raging through the European scientific community concerning the nature of light: was it a wave, like sound, or was it, as Isaac Newton had suggested, composed of particles? In his Principia Mathematica, Newton attempted to prove his theory by using a prism to split light, spreading the particles away from one another; white light, he concluded, must be a composite of all the colored particles traveling together through a vacuum.
This was a difficult concept for Huygens to envision because his earlier conversations with Descartes had taught him that nature is mechanical--that all phenomena are caused by matter influencing other matter. Thus, it seemed absolutely ridiculous that a group of particles could be created spontaneously and independently transfer themselves through a vacuum. He introduced his own wave theory of light in 1690, three years after Newton's Principia, that supported Descartes's view of the universe.
Huygens's wave theory of light was similar to that of the wave theory of sound. According to his theory, light was a series of pulsations similar to shock waves. These pulsations would travel longitudinally (with an in-and-out motion) through an invisible medium called the ether; each pulse would disturb the ether, pushing it in the direction of the light wave.
At the time of its publication, Huygens's wave theory of light was given little consideration, chiefly because scientists were reluctant to accept the notion of the invisible ether. As Newton's reputation grew, his particle theory became more and more popular, and the work of Huygens was all but forgotten. It was not until the nineteenth century that Thomas Young reintroduced the wave theory of light--this time without the dubious hypothesis of the ether.
It is not surprising that Huygens achieved little fame during his lifetime, for he published his work slowly and infrequently. He was also a recluse who chose not to take students. Still, he was instrumental in the foundation of the French Academy of Sciences and was a charter member of the British Royal Society. In addition to his clocks and his astronomical instruments, Huygens invented the manometer (a device used to measure the pressure of liquids and gases), as well as a prototype internal combustion engine using pistons.
This is the complete article, containing 1,499 words
(approx. 5 pages at 300 words per page).
