Dec 102018

Today is the birthday (1588) of Isaac Beeckman, a Dutch natural philosopher who is rarely spoken of today, but in his time was well respected, and was a leading figure in the development of many modern scientific theories, especially atomism.

Beeckman was born in Middelburg, Zeeland, to a strong Calvinistic family, which had fled from the Spanish-controlled Southern Netherlands a few years before. He had his early education in his home town and went on to study theology, literature and mathematics in Leiden. Upon his return to Middelburg he could not find a position as a minister, due to his father’s clashes with the local church, and decided to follow his father in the candle-making business, setting up his own company in Zierikzee. While trying to improve on the candle making process, he also involved himself in other projects, like creating water conduits and doing meteorological observations. In 1616 he sold the business to his apprentice and went to study medicine in Caen, where he graduated in 1618. On his return, he became an assistant rector in Utrecht. On April 1620 he married Cateline de Cerf, whom he knew from Middelburg, and with whom he would have seven children. From 1620 to 1627 he taught at the Latin school in Rotterdam, where he founded a “Collegium Mechanicum”, or Technical College. From 1627 until his death at the age of 48 he was rector of the Latin school in Dordrecht.

Rene Descartes and Isaac Beeckman.

Beeckman’s most influential teachers in Leiden probably were Snellius and Simon Stevin. He himself was a teacher to Johan de Witt and a teacher and friend of René Descartes. Beeckman had met the young Descartes in November 1618 in Breda, where Beeckman then lived and Descartes was then garrisoned as a soldier. It is said that they met when both were looking at a placard that was set up in the Breda marketplace, detailing a mathematical problem to be solved. Descartes asked Beeckman to translate the problem from Dutch to French. In their following meetings Beeckman interested Descartes in his corpuscularian approach to mechanical theory, and convinced him to devote his studies to a mathematical approach to nature. In 1619, Descartes dedicated one of his first tractati to him, the Compendium Musicae. When Descartes returned to the Dutch Republic in the autumn of 1628, Beeckman also introduced him to many of Galileo’s ideas. In 1629 they fell out over a dispute concerning whether Beeckman had helped Descartes with some of his mathematical discoveries. In October 1630, Descartes wrote a long and harshly abusive letter, apparently meant to crush Beeckman psychologically, in which he declared himself never to have been influenced by Beeckman. Despite a few other such fallings-outs, they remained in contact until Beeckman’s death in 1637.

Beeckman did not publish his ideas, but he had influenced many scientists of his time. Since the beginning of his studies he did keep an extensive journal, from which his brother published some of his observations in 1644. However, this went basically unnoticed. The scope of Beeckman’s ideas did not come to light until the science historian Cornelis de Waard rediscovered the Journaal in 1905, and published it in volumes between 1939 and 1953.

The following are key points in the Journaal:

Beeckman developed, independently of Sebastian Basso, the concept that matter is composed of atoms.

Beeckman is one of the first people to describe inertia correctly, although he also assumed that a constant circular velocity is conserved.

Beeckman showed that the fundamental frequency of a vibrating string is proportional to the reciprocal of the length of the string.

In the analysis of the functioning of a pump he theorized correctly that air pressure is the cause and not the then popular theory of horror vacui (“nature abhors a vacuum”

In his time, he was considered to be one of the most educated men in Europe. For example, he had deeply impressed French polymath Marin Mersenne, despite their opposing religious views, as well as astronomer and mathematician, Pierre Gassendi, who apparently had been introduced by Beeckman to the philosophy of Epicurus and atomism. Gassendi stated in a 1629 letter that Beeckman was the greatest philosopher he had ever met.

Here is a 16th century Dutch recipe for gooseberry omelet taken from Seer excellenten gheexperimenteerden nieuwen Coc-boeck (The very excellent and tried new cookbook) by Karel Baten (Carolus Battus) published in 1593:

Om een tasey van stekelbesyen te backen.
Neempt versche boter ende smeltse in een panne. Doeter dan soo vele stekelbesyen in datse bycans twee vyngeren hooch liggen ende laetse met de boter een weynich sieden tot datse maer recht hen coleur verloren hebben. Clopt dan wel cleyn 7, 8 ofte 9 eyeren met wat gengeber ende wat rooswaters. Gietet tsamen over de besyen ende latet so over een coolvyer backen dat niet en brande. Als de tasey genoech gebacken is, so laetse properlick uut de panne in de schotel rijsen datse niet en breke. Dan stroyter suycker ende caneel op ende dientse.

To bake an omelette of gooseberries.
Take fresh butter and melt it in a pan. Add gooseberries so that they are almost two fingers high and let them simmer in the butter until they have lost their color. Then beat 7, 8 or 9 eggs with a little ginger and rosewater. Pour this mixture over the gooseberries, and let it bake over a coal fire without burning. When the omelet is done, let it glide from the pan on to a dish without breaking. Then sprinkle sugar and cinnamon on it and serve.

Nov 212018

On this date in 1676, the Danish astronomer Ole Rømer published the first quantitative measurements of the speed of light. Until the early modern period, it was not known whether light travelled instantaneously or at a very fast finite speed. The first extant recorded examination of this subject was in ancient Greece. The ancient Greeks, Muslim scholars, and classical European scientists long debated this until Rømer provided the first calculation of the speed of light. Einstein’s Theory of Special Relativity concluded that the speed of light is constant regardless of one’s frame of reference. That is, if you are traveling towards a light source or away from it or stationary in relation to it, the light from the source comes at you at exactly the same speed. That is an astounding fact that most people fail to grasp. Today is also a milestone for Einstein and the speed of light which I posted on three years ago

Empedocles (c. 490–430 BC) was the first person to propose a theory of light, as far as we know, and he claimed that light has a finite speed. He maintained that light was something in motion, and therefore must take some time to travel. Aristotle argued, to the contrary, that “light is due to the presence of something, but it is not a movement.” Euclid and Ptolemy advanced Empedocles’ emission theory of vision, arguing that light is emitted from the eye, thus enabling sight. Based on that theory, Heron of Alexandria argued that the speed of light must be infinite because distant objects such as stars appear immediately upon opening the eyes.

Early Islamic philosophers initially agreed with the Aristotelian view that light had no speed of travel. In 1021, Alhazen (Ibn al-Haytham) published the Book of Optics, in which he presented a series of arguments dismissing the emission theory of vision in favor of the now accepted intromission theory, in which light moves from an object into the eye. This led Alhazen to propose that light must have a finite speed, and that the speed of light is variable, decreasing in denser bodies. He argued that light is substantial matter, the propagation of which requires time, even if this is hidden from our senses. Also in the 11th century, Abū Rayhān al-Bīrūnī agreed that light has a finite speed, and observed that the speed of light is much faster than the speed of sound. In the 13th century, Roger Bacon argued that the speed of light in air was not infinite, using philosophical arguments backed by the writing of Alhazen and Aristotle. In the 1270s, the friar/natural philosopher Witelo considered the possibility of light traveling at infinite speed in vacuum, but slowing down in denser bodies.

In the early 17th century, Johannes Kepler believed that the speed of light was infinite, since empty space presents no obstacle to it. René Descartes argued that if the speed of light were to be finite, the Sun, Earth, and Moon would be noticeably out of alignment during a lunar eclipse. Since such misalignment had not been observed, Descartes concluded the speed of light was infinite. Descartes speculated that if the speed of light were found to be finite, his whole system of philosophy might be demolished. In Descartes’ derivation of Snell’s law (concerning the angle that light refracts when passing through media of different densities), he assumed that even though the speed of light was instantaneous, the denser the medium, the faster was light’s speed. Pierre de Fermat derived Snell’s law using the opposing assumption, the denser the medium the slower light traveled. Fermat also argued in support of a finite speed of light – and, of course, if you know your physics, Fermat was right and Descartes was wrong.

In 1629, Isaac Beeckman proposed an experiment in which a person observes the flash of a cannon reflecting off a mirror about one mile (1.6 km) away. In 1638, Galileo Galilei proposed an experiment, with an apparent claim to having performed it some years earlier, to measure the speed of light by observing the delay between uncovering a lantern and its perception some distance away. He was unable to distinguish whether light travel was instantaneous or not, but concluded that if it were not, it must nevertheless be extraordinarily rapid. In 1667, the Accademia del Cimento of Florence reported that it had performed Galileo’s experiment, with the lanterns separated by about one mile, but no delay was observed. The actual delay in this experiment would have been about 11 microseconds.


The first quantitative estimate of the speed of light was made in 1676 by Rømer. From the observation that the periods of Jupiter’s innermost moon Io appeared to be shorter when the Earth was approaching Jupiter than when receding from it, he concluded that light travels at a finite speed, and estimated that it takes light 22 minutes to cross the diameter of Earth’s orbit. Christiaan Huygens combined this estimate with an estimate for the diameter of the Earth’s orbit to obtain an estimate of speed of light of 220000 km/s, 26% lower than the actual value.

In his 1704 book Opticks, Isaac Newton reported Rømer’s calculations of the finite speed of light and gave a value of “seven or eight minutes” for the time taken for light to travel from the Sun to the Earth (the modern value is 8 minutes 19 seconds). Newton queried whether Rømer’s eclipse shadows were colored; hearing that they were not, he concluded the different colors traveled at the same speed. In 1729, James Bradley discovered stellar aberration. From this effect he determined that light must travel 10,210 times faster than the Earth in its orbit (the modern figure is 10,066 times faster) or, equivalently, that it would take light 8 minutes 12 seconds to travel from the Sun to the Earth.

I’ll return to molecular gastronomy one more time for this physics post to be consistent, even though there’s an awful lot of spherical liquid things involved. It does get a tad tiresome after a while.