Robert Bunsen

Lived 1811 – 1899.

Robert Bunsen discovered the antidote to arsenic poisoning. Years later, it saved his life. He invented the zinc-carbon battery; invented flash photography; showed how geysers function; and with Gustav Kirchhoff invented one of the most fruitful scientific methods in history: spectroscopy, which Bunsen and Kirchhoff used to discover the elements cesium and rubidium. His name is best remembered for his invention of the clean-burning Bunsen burners used in laboratories worldwide.

Robert Bunsen’s Early Life and Education

Robert Wilhelm Eberhard Bunsen was born on March 30, 1811, in Göttingen, Germany. He was the youngest of four sons.

His father was Christian Bunsen, professor of modern languages and head librarian at the University of Göttingen. His mother came from a military family. Bunsen once recalled that he had been a wayward child at times, but his mother kept him in line.

He attended elementary school and high school in Göttingen. When he reached the age of 15 he moved to the grammar school in Holzminden, about 40 miles (60 km) from Göttingen.

In 1828, aged 17, he started work for his degree at the University of Göttingen. He took courses in chemistry, physics, and mathematics, with some geology and botany. He won an award for his work on a humidity meter. When he wrote this work up in 1830, he was awarded a Ph.D. in chemistry – he was just 19 years old.

Bunsen stayed at Göttingen until he won a government scholarship to travel around Europe studying chemistry. He spend most of 1832 and 1833 learning chemical techniques in laboratories in Germany, Austria, Switzerland, and France. In France he spent time in Paris working with the famous chemist Joseph Gay-Lussac.

Recalling differences between his own time as a university student and many years later, Bunsen said:

“In my day, we studied science and not, as now so often happens, only one of them.”

Robert Bunsen’s Discoveries and Contributions to Science

Arsenic – A Triumph and a Disaster

In 1833, aged 22, Bunsen started working as a chemistry lecturer at the University of Göttingen. He had obtained his license to teach, but received no salary from the university. He tutored students and carried out research in the chemistry laboratories.

In the early years of his career, Bunsen researched arsenic compounds – hazardous work.

In 1834 he published his first important work. Working with the physician Arnold Berthold he discovered an antidote to arsenic poisoning.

He found that adding iron oxide hydrate to a solution in which arsenic compounds are dissolved causes the arsenic compounds to fall out of the solution as ferrous arsenate, which is an insoluble, harmless solid.

Bunsen developed an ongoing passion for studying the compounds of arsenic. Like the good chemist he was, he tried to take precautions against the toxic effects of these compounds: he devised a face mask with a breathing tube that fed him clean air from outdoors while he worked.

Some arsenic compounds, however, are explosive. Without warning, they explode in dry air. In 1843, nine years after finding the antidote to arsenic poisoning, Bunsen became a victim of such an explosion when a sample of an arsenic compound called cacodyl cyanide exploded, shattering his face mask and permanently blinding his right eye.

The explosion also resulted in Bunsen suffering severe arsenic poisoning.

He was saved from death by the iron oxide hydrate antidote he discovered nine years earlier.

Invention of the Zinc-Carbon Battery

In 1841 Bunsen invented the zinc-carbon cell – often called the Bunsen battery. He saw this as an improvement on the expensive Grove cell, which was used, for example, to power telegraph lines. The Grove cell was a zinc-platinum cell. The platinum in it made it very expensive.

Bunsen combined his zinc-carbon cells into large batteries, which he used to isolate metals from their ores. He was the first person to produce large scale samples of pure magnesium metal.

His replacement of expensive platinum with cheap carbon also allowed other researchers who had been deterred by costs to carry out work in electrochemistry.

Gas Analysis and Big Wins for Steel Making

Bunsen developed new techniques to analyze gases. Between 1838 and 1846 he used his methods to study gases produced by industries. He found that in the steel industry, where heat was produced by burning charcoal, much of the charcoal was not burning completely. It was burning to form carbon monoxide, rather than producing much more heat by burning efficiently to form carbon dioxide.

To improve efficiency, Bunsen recommended the exhaust gases from burning charcoal, full of carbon monoxide, should be recycled to generate more energy by burning them to form carbon dioxide. He estimated German furnaces were wasting 50 percent of their energy and British furnaces 80 percent. Eventually, the reluctant industries changed their ways and adopted Bunsen’s recommendations.

An Expedition to Iceland – Bunsen Discovers how Geysers Function

Bunsen was interested in both gas analysis and geology. He was invited to Iceland in 1846 to study volcanic activity, where he made fundamental contributions to geochemistry.

By bravely standing at the sides of geysers and lowering scientific apparatus into their depths, he discovered that geysers have at their base a reservoir of superheated water: this water is much hotter than 100 °C. It is kept liquid by high pressure below ground. As this water rises from below, the pressure falls, and the water boils explosively to form a geyser.

“The far northern scenery is absolutely desolate but is marvelously beautiful, and I shall never regret that I have seen it, even though it cost me the unbelievable privations and exertions which we suffer here.”

ROBERT BUNSEN

The Bunsen Burner

Chemists and alchemists before them were aware that if you sprinkled a sample of a substance into a flame, the color you saw helped you identify chemical elements in the sample. Lithium compounds, for example, burn with a rose-red flame, while potassium compounds burn with a lilac flame.

This is seen in the chemistry of fireworks, where different colors are produced using salts of different elements.

Bunsen observed that sodium compounds gave an orange-yellow flame.

However, the fundamental color of the flame itself, before chemicals were sprinkled into it, could interfere with the test, making it unreliable.

The Bunsen Burner

Bunsen’s response was his gas burner. By introducing air into the gas in the correct proportion before it burns, a clean, soot-free, almost colorless flame is produced. Using his burner, Bunsen used flame tests to analyze substances much more reliably than ever before.

The burners he designed were made by Peter Desaga, his laboratory assistant.

Bunsen published the design of the burner in 1857, but did not patent his design. He did not wish to make profits from science; he believed the intellectual rewards were more than enough.

His burner is now used not only for flame tests. It is used to heat samples and to sterilize equipment in medical laboratories all over the world.

The Spectrometer and Discovery of New Elements

Bunsen’s friend and colleague Gustav Kirchhoff was interested in the infant science of spectroscopy.

Spectroscopy was the science of splitting sunlight into the colors of the rainbow using a prism – much as Isaac Newton did in 1666.

A prism splits a beam of sunlight into a colored spectrum of light.

Many years later, in 1802, William Hyde Wollaston repeated Newton’s experiment, but looked at the spectrum of sunlight using a magnifying glass. He saw more than the colors of the rainbow: he saw seven dark lines within the colors.

In 1812, Josef Fraunhofer looked at a greatly magnified spectrum of colors from sunlight and saw over 500 of these dark lines. (We now know there are more than 3000 lines.)

Fraunhofer could not explain the lines.

Fraunhofer saw dark lines when he magnified the spectrum of sunlight from a prism.

Enter Gustav Kirchhoff.

Bunsen had first met Kirchhoff and worked with him at the University of Breslau, when he spent a year there in 1851. In 1852, Bunsen took the Chair of Chemistry at Heidelberg University. In 1854, he arranged that his friend Kirchhoff should follow him, to take the Chair of Physics. The pair then formed a highly productive research partnership.

Kirchhoff was interested in the new science of spectroscopy. He wanted to explain the dark lines in the sun’s spectrum. He made the historic discovery that they were caused by cooler gases in the sun’s atmosphere absorbing particular wavelengths of sunlight. These dark-lined spectra are now called absorption spectra.

In 1859, Kirchhoff and Bunsen brought together a spectroscope and a Bunsen burner to study spectra from Bunsen’s flame tests. The two scientists looked at the spectra of a variety of different substances in the hot flame of the Bunsen burner.

The Bunsen-Kirchhoff Spectroscope with Bunsen Burner

KEY: (A) Box, colored black on the inside; (B) & (C) Telescopes; (D) Bunsen Burner; (E) Sample Holder; (F) Prism; (G) Mirror; (H) Handle to rotate prism and mirror.

The results were stunning. Bright lines appeared in the spectrum: the elements, when strongly heated in the Bunsen burner’s flame, emitted light at particular colors or wavelengths. These bright-lined spectra are now called emission spectra.

Lines in the spectrum turned out to be a reliable ‘fingerprint’ for chemical elements. Every element absorbs or emits characteristic wavelengths of light, leading to different ‘fingerprints’ of lines for the different elements.

Emission Spectrum of Hydrogen

Emission Spectrum of Iron

A new science had been born – chemical spectroscopy.

Using their newly invented method, Bunsen and Kirchhoff discovered two new elements: cesium in 1860, and rubidium in 1861.

The beauty of spectroscopy is that tiny traces of a substance can be detected. This opened up a whole new field of chemical analysis where elements could be detected when their concentrations were exceptionally low.

For example, Bunsen and Kirchhoff’s spectroscope revealed the new element cesium, even though there was only a tiny amount of cesium in the mineral water it was discovered in. In fact, when Bunsen tried to get a sample of the new element, he had to process 40 tons of mineral water to extract 50 grams of cesium salt from it.

After Bunsen and Kirchhoff published their work, other scientists quickly realized the power of the new technology. This led to the discovery of more elements, including indium (1863), helium (1868), europium (1896), gallium (1875), and hafnium (1922).

Kirchhoff identified some of the elements present in the sun. Other scientists looked to the stars and discovered they are made of exactly the same elements as we find in our sun and on our earth.

Today, spectroscopy encompasses all wavelengths of the electromagnetic spectrum, not just visible light. It is an enormously valuable method for solving a huge variety of scientific problems. Even living things can be analyzed with spectroscopy, such as when magnetic resonance spectroscopy is used to identify diseases in people.

Invention of Flash Photography

In 1864, Bunsen and his research student Henry Enfield Roscoe invented flash photography when they used the intense, bright light from burning magnesium as a light source to allow photographs to be taken in poor ambient light.

The Man

Bunsen never married and had no children.

He had a reputation as a fun person to be around, full of laughter, but not too careful about his personal appearance – he had better uses for his time than wasting it over selecting clothes and looking at himself in the mirror. Another professor’s wife once said that she would like to kiss him, but she would have to wash him first!

He had a great reputation for warmheartedness, and enjoying jokes and fun. His students admired him greatly. He told a great many anecdotes, published after his death in a short book called Bunseniana.

His work with arsenic, and with poisonous gases, his study of explosive chemical reactions, and his willingness to take equipment into the craters of active volcanoes and to lower it into geysers suggests he enjoyed living dangerously. In 1868 there was another explosion in his laboratory. This one involved iridium and rhodium metal powders, which can ignite spontaneously in air. Bunsen wrote:

“It is still difficult for me to write, as my hands are not quite healed… on touching the finely divided metal… with my finger, the whole suddenly exploded with the energy of rammed-in gunpowder… My left hand… saved my eyes, as my face and eyes were only superficially burnt by the flames which penetrated through my fingers. My eyes are, with the exception of singed eyebrows and eyelashes, unhurt, and so the explosion will luckily leave behind no serious traces.”

One of Bunsen’s favorite activities was walking in the woodland and hills around Heidelberg – here he got time to think. On these walks, he said, his best ideas would come to him.

Bunsen did a great deal of his laboratory work personally. He was a skilled glass blower, and he preferred doing experiments to anything else in science.

“As an investigator he was great, as a teacher he was greater, as a man and friend he was greatest.”

SIR HENRY ENFIELD ROSCOE, 1833 – 1915

Chemist

Awards

Bunsen worked in pre-Nobel prize days. In 1860 he was awarded the equivalent of the Nobel Prize, in the form of the British Royal Society’s Copley Medal; he also won the Royal Society’s Davy Medal in 1877. He was elected foreign member of the Royal Society, and in 1883 became one of eight foreign members of the French Academy of Sciences.

The End

Robert Bunsen died aged 88 on August 16, 1899 in Heidelberg.

Brahmagupta

Lived 597 – 668 AD

Brahmagupta is unique. He is the only scientist we have to thank for discovering the properties of precisely zero…

Brahmagupta was an Ancient Indian astronomer and mathematician who lived from 597 AD to 668 AD. He was born in the city of Bhinmal in Northwest India. His father, whose name was Jisnugupta, was an astrologer.

Although Brahmagupta thought of himself as an astronomer who did some mathematics, he is now mainly remembered for his contributions to mathematics.

Many of his important discoveries were written as poetry rather than as mathematical equations! Nevertheless, truth is truth, regardless of how it may be written.

Quick Guide to Brahmagupta

Brahmagupta:

• was the director of the astronomical observatory of Ujjain, the center of Ancient Indian mathematical astronomy.

• wrote four books about astronomy and mathematics, the most famous of which is Brahma-sphuta-siddhanta ( Brahma’s Correct System of Astronomy, or The Opening of the Universe.)

• said solving mathematical problems was something he did for pleasure.

• was the first person in history to define the properties of the number zero. Identifying zero as a number whose properties needed to be defined was vital for the future of mathematics and science.

• defined zero as the number you get when you subtract a number from itself.

• said that zero divided by any other number is zero.

• said dividing zero by zero produces zero. (Although, this seems reasonable, Brahmagupta actually got this one wrong. Mathematicians have now shown that zero divided by zero is undefined – it has no meaning. There really is no answer to zero divided by zero.)

• was the first person to discover the formula for solving quadratic equations.

• wrote that pi, the ratio of a circle’s circumference to its diameter, could usually be taken to be 3, but if accuracy were needed, then the square-root of 10 (this equals 3.162…) should be used. This is about 0.66 percent higher than the true value of pi.

• indicated that Earth is nearer the moon than the sun

• incorrectly said that Earth did not spin and that Earth does not orbit the sun. This, however, may have been for reasons of self-preservation. Opposing the Brahmins’ religious myths of the time would have been dangerous.

• produced a formula to find the area of any four-sided shape whose corners touch the inside of a circle. This actually simplifies to Heron’s formula for triangles.

• said the length of a year is 365 days 6 hours 12 minutes 9 seconds.

• calculated that Earth is a sphere of circumference around 36,000 km (22,500 miles).

Brahmagupta established rules for working with positive and negative numbers, such as:

• adding two negative numbers together always results in a negative number.

• subtracting a negative number from a positive number is the same as adding the two numbers.

• multiplying two negative numbers together is the same as multiplying two positive numbers.

• dividing a positive number by a negative, or a negative number by a positive results in a negative number.

Why is Zero Important?

Although it may seem obvious to us now that zero is a number, and obvious that we can produce it by subtracting a number from itself, and that dividing zero by a non-zero number gives an answer of zero, these results are not actually obvious.

The brilliant mathematicians of Ancient Greece, so far ahead of their time in many ways, had not been able to make this breakthrough. Neither had anyone else, until Brahmagupta came along!

It was a huge conceptual leap to see that zero is a number in its own right. Once this leap had been made, mathematics and science could make progress that would otherwise have been impossible.

Update September 14, 2017
Scientists at the University of Oxford have established that an Indian manuscript dated 200-400 AD is the first documented use of zero, as shown in the video below. Zero was invented before Brahmagupta’s era!

Tycho Brahe

Lived 1546 – 1601.

Tycho Brahe was a larger than life aristocratic astronomer whose observations became the foundation for a new understanding of the solar system and ultimately gravity. Brought up by an uncle who had kidnapped him, Tycho defied both his natural and foster parents to become a scientist rather than a nobleman at the Royal Court.

Never one to refuse liquor or back down in an argument, as a young man he lost most of his nose in a duel. He continued to argue vehemently with a variety of foes for the rest of his life.

In addition to being an extraordinary character, Tycho was a brilliant astronomer, whose work was substantially more accurate than his peers. His lunar theory was the best ever devised, and he produced data for the best star catalog that had ever been compiled. His outstandingly rigorous observations enabled his one-time assistant Johannes Kepler to discover that planets move around the sun in elliptical orbits.

Beginnings

Tycho Ottesen Brahe was born into a highly aristocratic, very wealthy family on December 14, 1546. He was born in his parents’ large manor house at Knutstorp, in the Danish region of Scarnia, which is now in Sweden.

Tycho’s father was Otte Brahe, a member of the Royal Court. His mother was Beate Bille, also an important aristocrat. Tycho was the second of the couple’s 12 children.

Although we usually refer to scientists by their surnames, in some cases we use their first names – Galileo, for example. This is also the case with Tycho Brahe, who is usually referred to simply as Tycho, pronounced ‘Teeko.’

Kidnapped

Something rather remarkable happened to Tycho in his second year of life – he was kidnapped by his uncle and aunt, Jørgen Brahe and Inger Oxe, when his parents were away from home. Tycho’s uncle and aunt were childless, and they believed that Jørgen was entitled to a lawful son and heir to his estates. Tycho’s natural parents eventually agreed to this, so Tycho was raised by his uncle and aunt as if he were their own son.

A Scholar, Not a Warrior

The Brahe family was powerful and militaristic. By tradition their male children became warriors serving the interests of the family, the King, and the Danish nobility.

However, Tycho’s foster mother, Inger, had come from an academic family and she persuaded her husband that Tycho should receive an academic education.

Tycho began school aged six or seven, a grammar school where he probably learned the classical languages, mathematics, and the Lutheran religion.

Brahe’s Lifetime in Context

Brahe’s lifetime and the lifetimes of related scientists and mathematicians.

University and Astronomy

In April 1559, aged 12, Tycho matriculated at the University of Copenhagen. He studied a general classical curriculum for three years, during which time he became increasingly absorbed in astronomy. He bought a number of important books in the field, including Johannes de Sacrobosco’s On the Spheres, Peter Abian’s Cosmography, and Regiomantus’s Trigonometry.

Tycho’s interest in astronomy began with the solar eclipse of August 21, 1560. In Copenhagen this eclipse was barely noticeable – less than half of the sun was covered. The eclipse inspired Tycho not because it was spectacular, but because astronomers had predicted exactly when it would happen. Tycho was fascinated, and wanted to learn how he too could make predictions like this.

Astronomy was actually an excellent fit for Tycho’s mathematical skills and his eye for detail.

Germany and a Discovery

The second century BC astronomer Hipparchus makes observations. In the 1560s astronomers still used similar equipment.

In March 1562, aged 15, Tycho matriculated at the University of Leipzig in Germany, where again he followed a classical curriculum.

He was supervised at Leipzig by Anders Vedel, a well-educated, twenty-year-old Dane. Vedel was appointed by Tycho’s foster parents, who had decided Tycho’s future career would be as a legal advisor at the Royal Court.

Vedel was tasked with keeping the rather headstrong Tycho on the straight and narrow, but he did not succeed. Tycho secretly continued to devote as much time as he could to astronomy.

Using just a basic, fist-sized celestial sphere and string, Tycho discovered that tables of predictions of planet positions sourced from the works of both Ptolemy and Nicolaus Copernicus were rather unsatisfactory.

A Purpose in Life

In August 1563, aged 16, Tycho began his first logbook of astronomical observations.

An astronomer in the 1500s makes observations using a cross staff.

He observed a one-in-twenty-year conjunction of Jupiter and Saturn, and again noted errors in both Copernicus’s and Ptolemy’s predictions. Using Ptolemy’s data tables, the conjunction timing was wrong by a month!

It became Tycho’s goal to produce truly accurate predictions of planetary positions based on accurate observations.

In April 1564, aged 17, Tycho bought a cross staff to make his observations. The cross staff was so large that his supervisor must have been aware Tycho was devoting time to astronomy. Tycho did not care – there was no need for secrecy any more. He had decided that astronomy would be his life’s work.

Denmark and Death

In the summer of 1565, Tycho returned to Denmark, where his step-father Jørgen had been in the process of making Tycho his legal heir. Unfortunately for Jørgen and Tycho, a war with Sweden intervened.

Jørgen was appointed Vice Admiral of the Danish Fleet and died of pneumonia in the summer of 1565 after falling into the water. Tycho inherited nothing, because the paperwork making him Jørgen’s legal heir was incomplete.

The law said that everything went in trust to his foster-mother. When she died Jørgen’s estates were to be distributed among the whole Brahe family.

A Nose for Trouble

In April 1566, aged 19, Tycho arrived back in Germany. On a December evening he got into argument with another Danish student who, like him, was studying at the University of Rostock.

The cause of the argument is not known. Sometimes it’s claimed they were arguing about which of them was the better mathematician, but this is probably a myth. No doubt alcohol played a part in the dispute – Tycho enjoyed dining and drinking heartily.

After further disagreements, the two students fought a duel with swords, which resulted in Tycho losing the front of his nose and picking up a permanent scar on his forehead. A year later, he returned to Denmark, where he began experimenting with metal fittings to disguise his nose’s disfigurement. He wore a skin-colored metal prosthetic for the rest of his life.

Getting Serious

At the end of 1567, Tycho left Denmark again for a tour of Germany and Switzerland. He was now 21.

In spring 1569, he arrived in Augsburg, where he spent 14 months learning how to make high-precision astronomical instruments. His ambition was to build instruments allowing him to make observations true to within one arc minute (one-sixtieth of a degree).

The first instruments designed by Tycho Brahe in Augsburg. On the left, an instrument to measure the angle between heavenly bodies. On the right an enormous quadrant whose radius was 5.5 meters.

Death and Wealth

When news reached him that his natural father, Otte Brahe, was ailing, Tycho returned to Denmark. His father died in May 1571, leaving 23-year-old Tycho a substantial legacy.

Tycho Brahe’s Contributions to Science

Astronomy without a Telescope

Galileo Galilei studied the heavens with a telescope for the first time in 1609. Sadly, Tycho did not live long enough to see this. All his observations were made with the naked eye, using the finest astronomical instruments in Europe.

Although he did not quite succeed in his ambition to make all his measurements accurate to with one arc minute, many of them did meet this standard, and his observations were a phenomenal five times more accurate than his peers made.

The New Star

Tycho made his first significant discovery on November 11, 1572. Observing the night sky from an uncle’s home, Tycho was amazed to see a new light brighter than Venus in the sky.

He studied the new heavenly body for a year. He deduced that it was a star because, unlike closer bodies such as the planets, its position relative to the other stars did not change.

In 1573, Tycho’s name became well-known in astronomical circles when he published De nova stella– The New Star. Although other people had also observed the new star, Tycho published the most comprehensive study of it.

Tycho’s new star gradually faded until, after a year, it was no longer visible to the naked eye.

The Latin word nova is still used for stars that suddenly get brighter. We now know that Tycho’s new star was actually a supernova.

Tycho’s observation of the new star, showing its location compared with other named stars. On the right is a modern X-ray image of the remnants of Tycho’s supernova, cataloged as SN 1572.

Tycho’s discovery was another nail in the coffin for Aristotle’s world view that the heavens beyond the moon are perfect and unchanging. Hipparchus had previously refuted Aristotle’s view with his observation of a new star in 134 BC.

The Distance to a Comet

Tycho’s sketch of the comet orbiting the sun. The comet’s tail points away from the sun.

The Great Comet of 1577 made people fearful, because comets were seen as bad omens.

Tycho recorded the comet’s positions between November 13, 1577 and January 26, 1578, after which he could no longer see it.

Tycho used Hipparchus’s parallax method to measure the comet’s distance from the earth.

Unfortunately, there was insufficient parallax for him to pin down the distance, but he was able to say that:

• The comet was much farther away from our planet than the moon is – at least six times as far. This refuted the popular idea that comets traveled within the earth’s atmosphere.
• The comet’s tail always pointed away from the sun.
• The comet’s path was associated with the sun, not the earth.

A Balanced Response to Comets, Doom, and Gloom

As was customary, Tycho wrote to the King with astrological predictions based on the comet’s appearance. He followed the usual line that the comet was a sign of bad things to come.

Unusually for the time, however, his recommendations did not focus on the supernatural. He told the King that the comet’s negative effects could be moderated if suitable policies were used in governance and if people used their free will in a levelheaded way.

A New Star Catalog

The comet had another far-reaching consequence for Tycho and science. It prompted him to begin making observations with a view to producing his own star catalogue to replace Ptolemy’s ancient work.

Tycho accurately recorded the positions of 777 stars by 1592, and he eventually amassed data for 1,006 stars. Tycho’s catalog was later worked on and published by Johannes Kepler.

Uraniborg – Fortress of Astronomy

The King wished to reward Tycho for some diplomatic work he had performed and awarded him the 3 square mile (7.5 sq. km) Danish island of Hven. On this island, in about 1580, Tycho completed the construction of Uraniborg, a palace-observatory, named after Urania, the Muse of Astronomy.

Plan of Stjerneborg showing the underground observing chambers.

Tycho’s island was rather windy and he realized he could never make highly precise astronomical measurements unless he had perfect stillness.

He decided to build an underground observatory, which he completed in 1581. Tycho called his underground observatory Stjerneborg, meaning Star Castle.

Tycho now carried out research on a scale few other astronomers could match. He was the wealthiest scientist in Europe and his work at Uraniborg was also generously supported by the King.

He employed skilled workers to build him the very finest astronomical instruments, and he attracted flocks of students eager to become disciples in the astronomical temples of Uraniborg and Stjerneborg.

Shattering the Heavenly Spheres

Michael Maestlin, the German astronomer who became Johannes Kepler’s teacher, had also observed the 1577 comet. Although his instruments were less sophisticated that Tycho’s, he had analyzed the comet’s movement in greater detail than Tycho. Where Tycho said the comet was a least 6 times farther away than the moon, Maestlin had calculated the comet’s daily distance from the earth.

Maestlin asserted that the comet had moved from about 3 times farther away than the moon to 30 times farther away than the moon.

This implied that the comet must have traveled through the ‘crystal spheres’ of Mercury and Venus.

Since Aristotle’s time, people believed planets were held in orbit around the earth by concentric ‘heavenly spheres.’ In Tycho’s time these spheres were imagined to be hard, clear, and crystalline.

In 1586, Cristoph Rothmann wrote Tycho pointing out that comets’ paths carried them through the crystal spheres.

Tycho was stunned by the thought that comets could break through the crystal spheres. Could it be that the spheres did not exist?

Other scientists had also questioned the substance of the heavenly spheres. Jean Pena in Paris, for example, had rejected them in 1557 based on light refraction.

Tycho’s System

If the heavenly spheres were not real, then what did the universe really look like?

Tycho was familiar with the concepts of the earth-centered solar system and the sun-centered solar system. The mathematics for these systems had been presented by Ptolemy and Copernicus respectively. Tycho was dissatisfied with their efforts – even as a 15-year-old he saw flaws in the planet positions predicted by their models. He also thought the earth was simply too heavy to fly at an enormous speed through the heavens as Copernicus’s system suggested.

Tycho tried to produce a model consistent with the best of both Ptolemy and Copernicus. He said that Copernicus was right – the five planets Mercury, Venus, Mars, Jupiter and Saturn – do orbit the sun. However, the moon, the sun and the stars orbit the earth, as Ptolemy had said.

The Tychonic System. Earth is at the center of the universe. The moon, the sun, and the stars orbit the earth. The five planets orbit the sun.

Tycho could only conceive of such a system because he threw away the idea that crystalline spheres hold the heavenly bodies in their orbits. At first Tycho said he:

“could not bring myself to allow this ridiculous penetration of the orbs, so that for some time, this, my own discovery, was suspect to me.”

TYCHO BRAHE

Letter to Caspar Peucer, 1588

 

Although to modern minds discarding the crystal spheres may seem trivial, in Tycho’s times it was revolutionary. Tycho removed a major obstacle to our understanding of the universe, because if there were no crystal spheres, something else must hold the heavenly bodies in their orbits.

In 1588, Tycho published details of his system and his great comet observations in a book entitled De Mundi Aetherei Recentioribus Phaenomenis Liber Secundus(The Second Book About Recent Phenomena in the Celestial World). Often the book is called simply De Mundi.

The book and Tycho’s system were popular. Unlike the works of Copernicus and Galileo, Tycho’s works were not later banned by the Catholic Church. When Galileo claimed his discovery of Venus’s phases proved Copernicus was right, the Church pointed out that his discovery was also consistent with Tycho’s earth-centered universe.

Lunar Theory

The moon’s movements are fiendishly difficult to understand mathematically. Differences between the moon’s true behavior versus its predicted behavior had been a thorn in the side of astronomers for thousands of years. Tycho’s lunar theory was a tremendous success, reducing the variations between theory and observed to one-fifth of those from Ptolemy’s theory.

In one of his most brilliant pieces of work, in 1595 Tycho discovered the variation of the Moon’s longitude, and that the moon’s oscillations on its orbital plane relative to the ecliptic are not a constant 5 degrees, but vary between 5 and 5¼ degrees. From this, he was able to reason, correctly, that there are oscillations in the longitude of the lunar nodes.

Tycho Leaves Uraniborg Forever

In 1597, Tycho left Uraniborg and Denmark forever after major disagreements with Denmark’s King. He spent some time in Germany until, in 1599, Holy Roman Emperor Rudolph II invited him to become his imperial mathematician.

Tycho accepted a manor house in Benatek, which today is situated in the Czech Republic. He worked there for a year, then Rudolph summoned him to live in Prague, where he valued Tycho’s horoscopes.

Rudolphine Tables

Tycho left Uraniborg with a precious cargo – almost two decades worth of accurate observations of the stars and planets he and his many research workers made there.

In Prague, Tycho gave Johannes Kepler a job as his assistant. Together, they began working on a new star catalog, but it was slow work. The catalog was eventually published by Kepler in 1627 as the Rudolphine Tables. These were by far the most accurate astronomical data tables ever published, with planetary data and 1,006 star positions. The majority of stars were cataloged to within one arc minute accuracy, which had been Tycho’s ambition.

Kepler’s Elliptical Orbits

Kepler had absolute faith in Tycho’s data. He also had absolute faith that Copernicus was right about a sun-centered solar system. He also had absolute faith that the planets’ orbits were based on the circle, as both Copernicus and Ptolemy had believed.

When he found he could not fit Tycho’s data to Copernicus’s or Ptolemy’s mathematical models of planetary movements, he did not lose his faith in Tycho’s data. He concluded that he must be mistaken about another of his articles of faith. Kepler abandoned the circle rather than believe Tycho’s observations were wrong.

Without Tycho’s data – particularly his superlative records of the positions of Mars – Kepler could not have made his great discoveries of the laws of planetary motion.

“In Tycho Brahe divine goodness gave us the most careful observer, establishing an error of 8 arc minutes in the Ptolemaic calculation… these 8 arc minutes could not be ignored, they formed a great part of the work which led to a total reformation of astronomy.”

JOHANNES KEPLER

Gesammelte Vol. III, republished 1937

 

Some Personal Details and the End

A Difficult Man

Tycho Brahe could be high-handed in his dealings with people. The farmers on the island of Hven objected to the fact he made them work much harder than they were accustomed to.

At Uraniborg, the turnover of research workers was high, probably because many of the workers found Tycho difficult to work with.

Some also came as spies. For example, Nicholas Baer, known as Ursus, took details of Tycho’s instruments to a rival astronomer and also seems to have stolen Tycho’s new system for the solar system before it was fully formed. Tycho expelled Ursus from Uraniborg after Ursus was caught snooping among Tycho’s books.

Ursus later published the stolen work under his own name. Tycho – never one to pull his punches – described Ursus as:

“savage, inhuman, scurrilous, rotten and sycophantic.”

Funnily enough, in later life, Tycho replaced Urusus as Rudolph II’s imperial mathematician.

A Wife and Children

At the age of 25, Tycho committed a serious social offense; he took a woman who was not born an aristocrat as his partner. It was illegal for the young couple to marry in the usual way. However, provided they lived together for three years, their partnership would be recognized as a legal marriage. They did this and became husband and wife. Tycho’s wife was Kirsten Hansen, daughter of a Lutheran minister.

Tycho and Kirsten had eight children, six of whom survived to adulthood. The form of marriage between the couple meant their children were commoners, not entitled to enjoy any of the privileges of the nobility. Also, they could not inherit Tycho’s estates or his coat of arms.

Following his exile from Denmark, Tycho and his family ended up in the court of Holy Roman Emperor Rudolph II. There Tycho’s wife and children were treated as nobles.

A Bizarre Death

On October 13, 1601, Tycho attended a banquet in Prague. As usual, he had plenty to drink, but the meal carried on for a long time. Although desperate to urinate, he did not leave the table – it would have been very impolite to leave the table before the meal was formally over.

Tycho Brahe died aged 54 on October 24, 1601 in Prague. His premature death was probably caused by either a burst bladder or kidney failure resulting from an excessive amount of urea in his blood. A 2012 report following a forensic examination of Tycho’s remains said claims Tycho had been poisoned were unfounded.

Tycho was buried with great honors in Prague’s Tyn Cathedral.

Robert Boyle

Lived 1627 – 1691.

Robert Boyle put chemistry on a firm scientific footing, transforming it from a field bogged down in alchemy and mysticism into one based on measurement. He defined elements, compounds, and mixtures, and he coined the new term ‘chemical analysis,’ a field in which he made several powerful contributions.

He discovered Boyle’s Law – the first of the gas laws – relating the pressure of a gas to its volume; he established that electrical forces are transmitted through a vacuum, but sound is not; and he also stated that the movement of particles is responsible for heat. He was the first person to write specific experimental guidance for other scientists, telling them the importance of achieving reliable, repeatable results.

Beginnings

Robert Boyle was born into an aristocratic family on January 25, 1627 in Lismore Castle, in the small town of Lismore, Ireland.

His father was Richard Boyle, who had arrived from England in 1588 with a modest sum of money. Through a good marriage and a high level of business acumen he had grown immensely wealthy and become a large-scale landowner. With land ownership came the aristocratic title Earl of Cork. The land he bought had been confiscated from rebellious Irish noblemen and commoners by the army of Queen Elizabeth I of England, who was also Queen of Ireland.

Robert’s mother was Catherine Fenton, born in Ireland to a wealthy English family. Her father became Secretary of State in Ireland.

Robert was his parents’ fourteenth child. In his infancy he was sent to live with a poor Irish family. His father preferred his children to spend their early years this way, believing it toughened them up. Robert developed a stutter in this time.

Robert’s mother died when he was just two years old, and he never knew her. Some time after his mother’s death he returned to the family home, where he was tutored in French and Latin. He particularly enjoyed learning French.

Eton, the Grand Tour, Galileo and Inspiration
At the age of eight, Robert was sent to England’s most prestigious private school, Eton College; he spent three years there.

At the age of 12 he embarked on a lengthy tour of Europe with his older brother, Francis, and a tutor. This ‘Grand Tour’ was a traditional part of many wealthy people’s education, often including visits to the great classical sites of Italy and Greece. In fact, Robert spent much of his time in the Swiss city of Geneva.

He traveled to Italy at the age of 14, learning there how Galileo Galilei had used mathematics to explain motion. Robert was thrilled by this and began studying Galileo’s work, presumably smuggled in from Switzerland, because it had been banned in Italy.

Galileo was in the final year of his life when Robert arrived in the great Italian city of Florence. Galileo lived close to Florence under house arrest; he died while Robert was in Florence. Robert approved of the idea promoted by Galileo and Nicolaus Copernicusthat the earth and other planets orbit the sun.

The young Robert Boyle was fascinated by Galileo’s belief that mathematics is the language of the world around us. The behavior of planets and pendulums, and the fundamentals of music and mechanics, could all be understood using mathematics.

While Robert was on his Grand Tour, his father died, leaving him a large country house near the English town of Stalbridge, plus large estates in Ireland.

In 1644, aged 17, Robert returned to England, staying for some months with his older sister Katherine in London. He then moved to his Stalbridge country house. All was not plain sailing, however, because in 1644 England was in the middle of a civil war caused by a power struggle between Parliament and the King.

An Alchemist in a Superstitious Age
Robert Boyle had no intention of getting involved in the war. He took a cautious approach, so that neither of the warring sides could see him as an enemy. He did not approve of the behavior of soldiers. A deeply religious young man, he was worried that involvement in military activities would corrupt him.

The country home near Stalbridge that Robert Boyle inherited from his father.

In fact, while war raged in England, Boyle spent time writing his first book. It concerned morality and was entitled Aretology.

He became increasingly interested in carrying out scientific experiments and studying scientific literature. He equipped a laboratory in 1646/7 and also began traveling to London for meetings with the ‘Philosophical College,’ a group dedicated to experimental science and the exchange of scientific ideas.

Like many budding scientists of his time, Robert Boyle tried his hand at alchemy. Not surprisingly, he was unsuccessful in his attempts to discover the Philosophers’ Stone: he described these as ‘chemistry.’

“Well, I see I am not designed to the finding out the Philosophers Stone, I have been so unlucky in my first attempts in chemistry.”

ROBERT BOYLE

March 6, 1647

 

Boyle lived in an extraordinarily superstitious age. The Enlightenment – the triumph of reason over superstition – that transformed much of Europe in the 1700s was still a long way off.

In Boyle’s time people lived in terror of (non-existent) witches and (all too real) witchfinders. Between 1644 and 1647 over 300 women in eastern England were killed for supposedly being witches after their ‘discovery’ by the notorious, self-appointed Witchfinder General, Matthew Hopkins.

England was also becoming increasingly puritanical: Parliament banned the celebration of Christmas in 1647, the ban remaining in place until 1660.

Boyle returned to his estates in Ireland in 1652, aged 25. He stayed there for two years, but grew increasingly unhappy in an environment he saw as unfavorable to his development as a scientist. He also suffered a serious illness, permanently affecting his eyesight. For the rest of his life he could read only very slowly and he had to employ people to do his writing for him.

Robert Boyle’s Contributions to Science

In 1654 or 1655, aged 27/28, Boyle moved to the university town of Oxford, England. There he hoped to find a scientifically productive environment. He rented rooms and set up a laboratory. He never officially joined the university; he was so wealthy that he needed neither salary nor funding for his experimental work.

In 1655 he had the good fortune to meet Robert Hooke, a young university student. Hooke’s extraordinary abilities with mechanical equipment impressed Boyle, who began paying him to work as his laboratory assistant.

Boyle’s Law

In 1654 Otto von Guericke had invented the vacuum pump. Boyle learned of this in 1657 and was intrigued. He discussed the concept of a vacuum pump with Hooke, who was able to improve on von Guericke’s design. Using Hooke’s pump Boyle and Hooke carried out experiments investigating the properties of air and the vacuum.

While experimenting with air, Boyle and Hooke made their first great discovery, now called Boyle’s Law. They made their discovery using a glass tube similar to the one shown at the top of this page. Inside the tube, they used mercury to vary the pressure on a fixed weight of air. Boyle discovered that pressure multiplied by volume is a constant. In other words, when you increase the pressure on a gas, the gas’s volume shrinks in a predictable way.

This was the first gas law to be discovered. Over a hundred years were to pass before the next gas law, Charles’ Law, was discovered in 1787.

A graph of Boyle’s actual experimental results. Reciprocal Volume is plotted vs. Pressure, producing a straight line. The data for the graph are taken from Boyle’s work: A Defence of the Doctrine Touching the Spring And Weight of the Air.

Boyle published this result in 1662. With its publication he emulated his hero Galileo for the first time. Galileo firmly believed that the world could be explained using mathematics – as indeed Pythagoras had in a much earlier age. Boyle had now shown by experiment that air follows mathematical laws.

The Properties of Air and the Vacuum

Boyle and Hooke’s vacuum pump.

Boyle discovered sound cannot travel through a vacuum.

He did this by ringing a bell housed inside a 28 liter glass jar. The bell was rung with the help of a magnet outside the jar. As he pumped air out of the jar, the sound of the bell grew fainter and fainter.

The vacuum pump is shown on the left. By turning the handle at the bottom, Boyle or Hooke could pump air out of the glass jar at the top.

Obviously, in performing this experiment, Boyle also showed that magnetic forces can travel through a vacuum – otherwise he could not have rung the bell. Although not fully appreciated at the time, this was actually a highly significant moment in science. Boyle had shown that physical forces could be transmitted across a vacuum.

Furthermore, he showed light can travel through a vacuum, because when air was pumped out of the jar, everything in the jar remained perfectly visible.

Using a candle, Boyle showed that a vacuum will not support combustion. He also found that only part of the air supports combustion – he thought a very small part. (At this stage, none of the elements that make up air had been discovered. Oxygen’s discovery lay over 100 years in the future.)

Boyle also showed that air has weight, although this had previously been shown in 1644 by Evangelista Torricelli – and seems to have been known by Empedocles 2,100 years earlier in Ancient Greece.

“Sound consists of an undulating motion of the air.”

ROBERT BOYLE

March 6, 1662

 

The Foundations of Modern Chemistry

Chemistry By Numbers

Published in 1661, Boyle’s The Sceptical Chymist, was a turning point in chemistry. Boyle began to detach chemistry from the mysticism of alchemy. He declared that most followers of alchemy were not interested in the fundamental causes of phenomena and instead looked to:

“… that sanctuary of the ignorant, occult qualities.”

ROBERT BOYLE

The Sceptical Chymist, 1661

 

At the heart of Boyle’s ambition for chemistry lay once again Galileo’s idea that the world could be understood through mathematics. Boyle wished to turn chemistry into a quantitative science.

Elements, Compounds, and Mixtures

Just as Galileo had rejected Aristotle’s theory of motion, Boyle now rejected the Aristotelian elements: earth, water, air and fire. He also rejected Paracelsus’s principles of salt, sulfur and mercury.

Boyle correctly defined elements as simple substances that could not be decomposed into other substances. Compounds were produced when elements combined to form new substances, unlike mixtures in which no new substances formed.

Having arrived at an excellent definition of an element, Boyle went on to say that he did not believe any true elements had yet been discovered. Unfortunately, he could not find an experimental method to prove whether a substance was an element or not, and he thought substances such as gold, silver and sulfur were actually compounds.

Over a century would pass before Antoine Lavoisiercould break through this experimental barrier and produce the first list of chemical elements.

Atoms – the Basis of all Matter

In Ancient Greece, Democritus said:

We think there is color, we think there is sweet, we think there is bitter, but in reality there are atoms and a void.

DEMOCRITUS, C. 460 – C. 370 BC

 

Boyle agreed with this. Galileo and René Descartesalso believed that all substances are made of atoms, but Descartes thought there could be no void. Boyle, however, had established from his own experiments that it was possible to have a void – a vacuum. As such, he was in complete agreement with Democritus.

Boyle believed that chemistry – the behavior of substances – could be explained through the motion of atoms, which in turn could be understood through mechanics – Galileo’s mathematics of motion. Boyle was ultimately proved correct, because today we can understand chemistry mathematically, through quantum mechanics.

Although he denounced mysticism, Boyle remained an alchemist, believing that one element could be transmuted into another. He thought, correctly, that this could be achieved through a rearrangement of the basic particles making up the element. This was first achieved by Ernest Rutherford in 1919 when he transformed nitrogen into oxygen.

Looking back at chemistry before Boyle began its reconstruction, Thomas Thomson said:

Chemistry, unlike other sciences, sprang originally from delusions and superstitions, and was at its commencement exactly on a par with magic and astrology.

THOMAS THOMSON, 1773 TO 1852

CHEMIST

 

Defining Good Experimental Science

Influenced by Francis Bacon’s emphasis on drawing general conclusions only after you had amassed experimental data, then drawing on his own personal experiences in the laboratory, Boyle made a major contribution to the future of science by clearly laying out how experimental science should be done.

Firstly, he had already made a clean break with the alchemists’ tradition of being secretive. Boyle openly published the results of his work.

He warned that impure chemicals could cause errors in experiments, as could incorrect use of equipment.

He explained how different people could honestly obtain very different results in an experiment, therefore experiments and their procedures needed to be carefully documented for others to see how they had been carried out.

He emphasized the need to repeat experiments. He said that doing so improved experimental techniques, and if different results were obtained after an experiment was repeated, the reasons for this must be explored.

He also implored people not to be disappointed if an experiment did not yield the hoped for results. He likened it to explorers who had been blown off course, only to discover new, unexpected regions.

“… even when we find not what we seek, we find something as well worth seeking as what we missed.”

ROBERT BOYLE

Of Unsucceeding Experiments, 1661

 

Heat is Mechanical Movement

Heat was very poorly understood until the 1800s. In the 1700s it was associated with the behavior of a non-existent substance called caloric.

Boyle, following in the footsteps of Galileo and Descartes, believed that heat is related to the movement of particles. In 1675 he offered a rather good description of the relationship between temperature and the movement of particles.

“Thus we see that the particles of water in its natural… state move so calmly that we do not feel it at all warm, though it could not be a liquid unless they were in a restless motion; but when water comes to be actually hot, the motion … is more vehement … And if the degree of Heat be such as to make the water boil, then the agitation becomes much more manifest by the confused motions … that are excited … which is able to throw up visibly into the air great store of corpuscles, in the form of vapors …”

ROBERT BOYLE

Of the Mechanical Origine of Heat and Cold, 1675

 

Electric Forces Operate in a Vacuum

In 1675 Boyle discovered that electric attraction operates in a vacuum.

Some Personal Details and the End

Although very wealthy, Boyle lived a relatively frugal, simple life, and was generous to other people. He was happy to spend large amounts of money on his experiments – he did not mind diminishing his wealth if by doing so he could learn some of Nature’s secrets.

In 1660 Boyle was a founding member of the Royal Society, the oldest scientific society in existence. The Society, dedicated to learning Nature’s secrets by experiment, took the motto Nullus In Verba – Take Nobody’s Word For It! The motto owes much to Boyle’s preference for rational experiment over superstitions and the theoretical speculations of philosophers. Earlier scientists, William Gilbertespecially, had also promoted this view.

In 1668, aged 41, Boyle left Oxford to live in his older sister Katherine’s house in London. These were unusual times: two years earlier almost a quarter of the city’s population had died in the Great Plague and most of the inhabitants of the central ancient city had lost their homes in the Great Fire.

Katherine was a significant person in London’s social and cultural scene. Boyle was not a very social person and he never married. Although, over the years, he received thousands of people into his laboratories with great hospitality, he preferred to work quietly on his own.

He continued with scientific experiments after equipping a laboratory in his sister’s house. This was not so strange because, like Robert, Katherine was an alchemist.

In 1670 Boyle suffered a rather severe stroke.

In 1680 he was elected as the Royal Society’s president, but refused to accept the position because his devout religious beliefs prevented him swearing the presidential oath.

Robert Boyle died of a stroke – or paralysis as it was then known – aged 64, on December 31, 1691, a week after the death of his sister Katherine. He was buried in a churchyard in Westminster, London. The churchyard was redeveloped in 1721 and Boyle’s remains were lost.