He was born in The Hague on April 1629. My father is a priest and poet. He has close contacts with academic celebrities such as R Descartes. Huygens was clever from an early age. 13 years old, making lathes by himself, showing strong hands-on ability. 1645- 1647 studied law and mathematics at Leiden university, 1647- 1649 transferred to Brayda college for further study. Under the direct influence of Archimedes and Descartes, he devoted himself to the study of mechanics, optics, astronomy and mathematics. He is good at combining scientific practice with theoretical research to solve problems thoroughly, so he has made outstanding achievements in the invention of pendulum, the design of astronomical instruments, the collision of elastic bodies and the theory of light fluctuation. 1663 was hired as the first foreign member of the Royal Society, and 1666 was elected as an academician of the newly established Royal French Academy of Sciences. Huygens was sickly, devoted to science and never married. 1695 died in The Hague on July 8th. Achievements ■ Summary
Huygens was in a wealthy and relaxed family and social conditions, and was persecuted from religion freely. He is good at combining scientific practice with theoretical research, thoroughly solving some important problems, and forming a working method combining theory with experiment and a clear physical thought. He left people with 68 kinds of scientific papers and works, including 22 volumes, and made great achievements in collision, pendulum, centrifugal force and fluctuation theory of light, optical instruments and so on.
■ Mathematical aspects
Huygens first concentrated on studying mathematical problems. Huygens has an outstanding talent in mathematics. As early as the age of 22, he published books on calculating circles, elliptical arcs and hyperbolas. He studied various plane curves, such as catenary (he found the difference between cycloid and parabola), drag line, logarithmic spiral and so on, and made great achievements in probability theory and calculus.
On Calculation in Gambling published by 1657 is a scientific paper on probability theory (he is the founder of probability theory), which shows his attainments in mathematics. Starting from 165 1, some works on circles, quadratic curves, complex curves, catenary, probability problems and so on have been published. He also studied floating bodies and looked for the center of gravity of objects of various shapes.
■ Optical aspects
Huygens principle is an important basic theory of modern optics. But although it can predict the existence of light diffraction, it can't explain these phenomena, that is, it can determine the propagation direction of light waves, but it can't determine the amplitude of vibration propagating in different directions. Therefore, Huygens principle is an approximate understanding of optical phenomena by human beings. It was not until later that Fresnel developed and supplemented Huygens' optical theory and founded Huygens-Fresnel principle that the diffraction phenomenon was well explained and the whole theory of light wave theory was completed.
Huygens' letter to the Paris Academy of Sciences in 1678 and his book On Light published in 1690 all expounded his light wave principle, namely Huygens' principle. Huygens principle holds that for any kind of wave, any point on the wave surface emitted by the wave source can be used as the wave source of wavelet, and the wave surface of each wavelet source is the next new wave surface. He believes that the particles of each emitter transmit pulses to an adjacent diffusion medium ("ether") particle, and each excited particle becomes the center of a spherical wavelet. Based on the elastic collision theory, he thinks that such a group of particles can propagate pulses in all directions at the same time, so the beams cross each other without affecting each other. On this basis, the reflection and refraction of light are explained as a graphic method. The most wonderful part of On Light is the birefringence model, which explains the strange phenomena caused by ordinary light and extraordinary light by means of spherical and ellipsoid propagation. There are dozens of complex geometric figures in the book, which is enough to illustrate his mathematical skills.
In addition, Huygens devoted himself to the study of optics during his work in Paris. 1678, he publicly opposed Newton's theory of light particles in a speech at the French Academy of Sciences. He said that if light is a particle, it will change direction when it passes through. However, people did not find this phenomenon at that time, and using particle theory to explain refraction phenomenon will get contradictory results with reality. Therefore, Huygens formally put forward the theory of light fluctuation in the book On Light published in 1690, and established the famous Huygens principle. On the basis of this principle, he deduced the law of reflection and refraction of light, which satisfactorily explained the reason why the speed of light decreased in dense media, and also explained the birefringence phenomenon after light entered Iceland spar, which was thought to be caused by oval molecular particles of Iceland spar.
■ Astronomical aspects
Huygens made a great contribution to astronomy. He designed and manufactured exquisite optical and astronomical instruments, such as grinding lenses and improving telescopes (Saturn's rings were discovered). ) and microscope, as well as Huygens eyepiece still in use today, as well as "Sky Telescope" (tubeless, long focal length, achromatic) and "Planetary Machine" that displays the starry sky (that is, the prototype of today's planetarium).
He devoted a lot of energy to developing and improving optical instruments. When Huygens was still in Holland, together with his brother, he successfully designed and ground the telescope lens with unprecedented accuracy, thus improving the Kepler telescope. Huygens made many astronomical observations with his own telescope. Therefore, his reward is to solve a long-standing astronomical mystery. Galileo once observed Saturn through a telescope. He found that "Saturn has ears", and later found that Saturn's "ears" disappeared. Scientists after Galileo have also studied this problem, but they have missed the point. "Saturn strange phenomenon" has become a mystery in astronomy. When Huygens aimed his improved telescope at the planet, he found a thin and flat ring beside Saturn, which was inclined to the orbital plane of the earth's revolution. Galileo discovered the disappearance of Saturn's ears because Saturn's rings sometimes look linear. Huygens later discovered Saturn's moon Titan, and also observed the Orion Nebula and the polar cap of Mars.
■ Research and application of pendulum
The study of pendulum is the best physical work Huygens has done.
1668 ~ 1669, he is one of the winners of the royal society collision paper award. He studied in detail the problem of completely elastic collision (then called "collision on the center"). After his death, he published it comprehensively in On the Collision Motion of Objects (1703), including five hypotheses, 65438+.
Huygens studied pendulum and its theory from both practice and theory. 1656, he first introduced the pendulum into clocks and watches, replacing the gravity gear clock in the past. In Pendulum Clock (1658) and Geometric Proof of the Motion of Pendulum Clock or Clock Pendulum (1673), he put forward the famous formula of the period of a simple pendulum. T. Huygens discovered the center of gravity of the object system and the moment of inertia that Euler later said, and introduced the physical idea of "feedback", which is more meaningful today. He designed a hairspring for a marine watch, which greatly reduced the size of the watch. He also used a simple pendulum to calculate the accurate value of gravity acceleration, and suggested that the length of the second pendulum should be used as the natural length standard.
Huygens also put forward his centrifugal force theorem, and he also studied the centrifugal force of circular motion, the pendulum, the rotation of the object system, and the oblateness of the mud ball and the earth when they rotate. These studies promoted the later establishment of the law of universal gravitation. He raised many interesting and enlightening questions about centrifugal force.
For centuries, time measurement has been a difficult problem for human beings. At that time, timing devices such as sundials and hourglasses could not keep accurate in principle. It was not until Galileo discovered the synchronization of pendulum and Huygens applied pendulum to timer that mankind entered a new era of timing.
At that time, Huygens' interest focused on the observation of celestial bodies. In the experiment, he deeply realized the importance of accurate timing, so he devoted himself to the research of accurate timer. Galileo once proved that the simple pendulum motion is similar to the sliding motion of an object on a smooth slope, and the state of the motion is related to the position. Huygens further confirmed the isochronism of the vibration of a simple pendulum, and applied it to a timer to make the world's first chronograph pendulum clock. This pendulum clock is made up of gears of different sizes and shapes. It uses a heavy hammer as a pendulum. Because the pendulum can be adjusted, the timing is more accurate. In the book On Pendulum, Huygens introduced the making process of pendulum in detail, analyzed the swinging process and characteristics of pendulum, and introduced the concept of "swinging center" for the first time. He pointed out that when an object of arbitrary shape swings around the horizontal axis under the action of gravity, its mass can be regarded as concentrated at a certain point on the line between the suspension point and the center of gravity, thus simplifying the swing of complex objects into a simple pendulum motion to study.
Huygens also gave the basic proposition about the so-called "centrifugal force" in his pendulum theory. He proposed that an object moving in a circle tends to fly away from the center, and the centrifugal force it exerts on the center is directly proportional to the square of velocity and inversely proportional to the radius of motion. This is also his expansion of Galileo's swing theory.
When developing pendulum clock, Huygens further studied the movement of simple pendulum. He made the second pendulum (a simple pendulum with a period of 2 seconds) and deduced the motion formula of the simple pendulum. When the pendulum length was accurately taken as 3.0565 feet, he calculated that the acceleration of gravity was 9.8 m/s 2. This value is exactly the same as the value we are using now.
Later, Huygens and Hooke also discovered the isochronous oscillation of the spiral spring wire, which created conditions for the invention of modern hairspring pocket watches and watches.
■ Mechanical aspects
In the study of mechanics, Huygens is based on Galileo's creation. In the book about pendulum clock, the problem of collision is also discussed. About 1669, Huygens put forward a law to solve the collision problem-the conservation principle of "vitality", which became the pioneer of energy conservation. Huygens inherited Galileo's theory of simple pendulum vibration and made further research on it. He brought geometry into the field of mechanics and dealt with mechanical problems in an admirable way, which was fully affirmed by people.
He is not superstitious about authority and dares to challenge it.