The Ancient Philosophers

3500 BC to 350 BC

During the Bronze Age, the first civilisations grew up in The Middle East. Later, in the Iron Age, The Persians, Egyptians, Greeks and Romans spread this culture through conquests and trade. Meanwhile, the Chinese were observing the heavens and starting their own culture and science.

Sumerians - City builders and arithmeticians (c. 3500 BC to 2000 BC)

The Sumerians lived in Mesopotamia. This region of fertile plains between the Tigris and the Euphrates is now mostly in modern Iraq. Here the Sumerians built the first advanced civilisation in great cities with administrations, legal systems and irrigation. They developed methods of writing and counting - in base 60.

In around 2300 BC, the Sumerians were invaded by the Akkadians. Between them, they invented the abacus and a basic arithmetic with addition, subtraction and versions of multiplication and division. The Sumerians were displaced by the Babylonians in around 2000 BC. But they passed on their systems of counting and arithmetic.

The Ancient Egyptians picked up Sumerian ideas on numbers The Babylonians invaded Sumeria and inherited their number system

Ancient Egyptians - Love geometry? Go to Ancient Egypt (c. 3000 BC to 320 BC)

Egyptian civilisation grew up around the Nile Delta from around 3000 BC. The Ancient Egyptians wrote using hieroglyphics drawn on papyrus or carved into stone. Many examples survive, including some mathematical ones.

Being hieroglyphic, the Egyptian number system had no zero and was not suited to multiplication or division. However, they found ways around this.

Their mathematics was very practical - usually to do with engineering projects or trade. However, they set and solved what we would recognise as algebraic problems. For example, 'a quantity added to a quarter of that quantity becomes 15. What is the quantity?'.

The Egyptians used a lot of geometry (due to the limitations of their number system) and probably passed to Pythagoras the theorem that was named after him. They are well known for the engineering triumph of the pyramids.

In about 3000 BC, they produced a very early calendar that had 365 days in the year and in around 1470 BC, Thutmosis III put up the 'Needle of Cleopatra' in Hliopolis. The needle's shadow was used to calculate the time, seasons and solstices.

The Ancient Egyptians picked up Sumerian ideas on numbers . Trade with the Babylonians meant a sharing of numbers and geometry . Greek philosophers like Thales were famliar with Egyptian geometry . The theorem to which Pythagoras gave his name was known to the Egyptians . Euclid would have been strongly influenced by the long Egyptian tradition in geometry .

Babylonians - Conquerors of Sumeria and number pinchers (c. 2000 BC to 100 BC)

The Babylonians invaded Sumeria in about 2100 BC. They set up their capital in Babylon, whose few ruins can be seen in the Iraqui desert south of Baghdad.

Babylonians inherited the Sumerian number system, counting in base 60. They divided the day into the hours, minutes and seconds that we use today. So we still count in base 60 - with 60 seconds in a minute and 60 minutes in an hour.

Although at first there was no representation of zero (so 536 would be the same as 5036), they began to leave a space, then used a symbol for zero in about 300 BC. Much later, this led to all sorts of mathematical possibilities - like multiplication and long division - which could not be done using Roman numerals or Egyptian hieroglyphics.

Even without zero, they devised ingenious methods to help them multiply or divide two numbers. For example, they could multiply two numbers using the formula ab = [(a + b)2 - (a - b)2]/4 and a stone tablets, or table, of squares.

Trade with the Ancient Egyptians meant a sharing of numbers and geometry . The Babylonians took the Sumerians' numbers as well as their country . Greek philosophers like Thales were famliar with Babylonian number systems . The theorem to which Pythagoras gave his name was well known to the Babylonians .

Thales of Miletus, philosopher - Played with a feather and some elektron? (c. 625 BC to 546 BC)

Greek philosopher, born in Miletus, Asia Minor, now Turkey.

Thales is best known for discovering static electricity and, as one of the Seven Wise Men, an early philosopher.

Thales' aim was to understand the nature of the physical world without relying on mythology or dogma. Instead, he questioned ideas and tried to understand phenomena - including heavenly ones. He became famous for predicting the eclipse of the Sun that occurred on May 28, 585 BC.

The story is that he noticed that he could pick up feathers with a piece of amber - so long as he rubbed it with cat fur. The effect took its name from the Greek for amber - elektron. From this, we get the modern words - electricity and electron.

Thales left no writings; knowledge of him is derived from an account in the Metaphysics of Aristotle.

Thales would have been familiar with the geometry of the Ancient Egyptians Pythagoras built on the philosophy of Thales Thales would have studies the number ideas of the Babylonians Democritus developed some of Thales ideas Aristotle was familiar with Thales philosophy William Gilbert coined the name electron 2000 years after Thales' experiments .

Pythagoras, philosopher and mathematician - Numbers, maths and music were all he needed (c. 569 BC to 475 BC)

Philosopher and mathematician born on the island of Samos.

Not much is known about the life of Pythagoras, except that he founded a community in Croton, southern Italy. He believed that we can understand the order of the world with the aid of mathematics and astronomy. As he put it: 'all is number'.

He proposed, in The Music of the Spheres that the movement of the planets was mathematically related to musical sounds. The connections that he established between music, astronomy, geometry and arithmetic exist to this day and remained strong until quite recently.

Pythagoras was best known for working out what we know as 'Pythagoras' Theorem'. Although, this was already known to the Egyptians and Babylonians, Pythagoras was probably the first to provide a rigorous proof.

The Egyptians knew, but probably never proved, his triangle theorem . The Babylonians knew, but probably never proved, Pythagoras' triangle theorem . Pythagoras built on the philosophical ideas of Thales . Aristotle went to Plato's academy and Plato was strongly influenced by Pythagoras' followers . Ptolemy formalised ideas about planets 400 years later

The geometry of the Greeks - including Pythagoras - was essential to the Arab mathematicians who followed them .

Anaxagoras, philosopher - A philosopher with real nous (c. 490 BC to 428 BC)

Greek philosopher, born in Clazomenae (now Turkey).

Anaxagoras explained his philosophy in Peri Physeos (On Nature), but only fragments of the books have survived.

He thought that all matter started off as infinitesimally small atoms; order was produced out of this infinite chaos through the influence of nous (Greek for 'mind' or 'reason').

Anaxogoras believed that there were an infinite number of elements at a time when the accepted view was that there were only four: fire, earth, air and water. He was the first person to explain correctly the reason for eclipses.

He set the scene for Democritus to develop his ideas of atoms and his doctrine of nous was adopted by Aristotle, who said that he sounded like the only sober man in a chorus of drunks.

In 450 BC Anaxagoras was imprisoned for suggesting that the Sun was not a god but a hot stone.

Aristotle adopted Anaxagoras' doctrine of nous . Anaxagoras' ideas on atoms were developed by Democritus Two thousand years later, Anaxagoras' ideas on the Sun influenced Copernicus and Galileo who, like him, faced

arrest for his work.

Democritus, philosopher - A paper ripper (at least in his mind) (c. 460 BC to 370 BC)

Greek philosopher, born in Abdera, Thrace.

Democritus considered what would happen if you kept ripping up a piece of paper. He reasoned that, eventually, you would reach a point where you couldn't rip any more. The paper (and everything else) must be made of tiny, indivisible blocks of different shapes and sizes. He called these blocks atoms (which means uncuttable).

He developed this idea to say that all changes in matter came from changes in the motion of the atoms, or changes in the way that they are packed together.

Democritus was harshly criticised for his ideas. At a time when beliefs and superstitions dominated the world, his atom theory seemed odd. People found it hard to accept the idea that everything, including human existence, is a product of mere atom collisions. This would leave everything to chance. Of course, although the belief systems are different, there is still a divide between those who are and are not comfortable with their fate being determined by physical rather than divine rules.

Democritus also wrote on ethics, proposing happiness, or 'cheerfulness', as the highest good - a condition to be achieved through moderation, tranquillity, and freedom from fear. Later historians sometimes referred to him as the Laughing Philosopher.

Anaxagoras gave Democritus ideas on atoms . Aristotle was the next great Greek philosopher after Democritus . Democritus' ideas on atoms were developed by Al-Razi in the 9th century AD .

Aristotle, philosopher - Teacher to Alexander the Great (384 BC to 322 BC)

Greek philosopher, born in Stagira in northeast Greece.

Aristotle believed that all knowledge must proceed directly from observation. He said that everything is made of the four elements (earth, fire air and water) which are only found on Earth. He later added another 'element' - ether, which surrounds heavenly bodies.

Aristotle made a distinction between what happened in the heavens (the celestial) and on the Earth (the terrestrial) . The heavens, being the domain of the gods, are ordered and stable; whereas the Earth is chaotic and changing under the influence of people. This distinction is still influential and it was Newton who broke its complete grip on philosophy when he proposed a Universal law of gravitation.

In his books On the Heavens, and Physics, he proposed a finite, spherical universe, with the Earth at its centre surrounded by concentric spheres which carry the planets and fixed stars. This geocentric theory of cosmology was the basis of European thought from the 12th century until it was challenged by Copernicus in the 1500's.

Aristotle is one of the 'big three' philosophers of ancient Greece (with Plato and Socrates). Socrates taught Plato, who in turn instructed Aristotle. After Plato's death, Aristotle travelled widely, teaching Alexander the Great, before founding his own school, The Lyceum, in Athens.

Democritus was the previous great Greek philosopher Archimedes studied in Alexandria which continued Aristotle's legacy . Euclid was based in Alexandria, which maintained Aristotle's legacy It wasn't until Copernicus nearly 2000 years later that Aristotle's ideas on the planets were replaced . Ibn Rushd took Aristotlean ideas into Europe in the Middle Ages, laying the foundations for the Renaissance . Aristotle's ideas on the separateness of the celestial and terrestrial survived until Newton in the 17th century .

Euclid, mathematician - The father of geometry (c.330 BC to 280 BC)

Greek mathematician who lived in Alexandria in Egypt.

Very little is known about Euclid's life except that he worked in Alexandria and published The Elements, the basic book on geometry.

He was probably educated in Athens by pupils of Plato. On moving to Alexandria, he would have had access to the Egyptians' strong tradition in geometry. In part, this would probably have been thanks to the Great Library in Alexandria, which was founded by Alexander the Great in 332 BC and housed over 7000 works.

Euclid's main work, The Elements, is a comprehensive treatise on mathematics. Its 13 volumes were used as a standard school text for the next 2300 years. Although much of it is probably original work, it is likely that he organised and explained more clearly ideas that were already in circulation. Nevertheless, because of The Elements and his work in this field, he is called the father of geometry.

Soon after Euclid, Eratosthenes (276 - 195 B.C.) developed the idea that the world is round and measured his latitude and the circumference of the Earth using the Sun's shadows.

Euclid built on and formalised much of the geometry of the Ancient Egyptians Archimedes studied in Alexandria and would have been the first of many students of Euclidian geometry . Ptolemy would have studied Euclid in Alexandria . Al Biruni would have studied Euclid's geometry Although Euclid wouldn't have overlapped with Aristotle, the Greek's legacy would be felt in Alexandria .

Archimedes, Sicilian philosopher - Eureka, you've found him! (c. 287 BC to 212 BC)

Sicilian philosopher, who studied in Alexandria and worked in Italy.

We believe that Archimedes studied under followers of Euclid in Alexandria before returning to Italy where he spent the rest of his life.

He is known for his mathematical work and applying science to everyday life. He worked out the principle of levers, calculated the surface areas and volumes of solids and invented a machine, the Archimedes screw, for raising water. This is still used in many parts of the world.

Legend has it that Archimedes discovered his famous principle of displacement while taking a bath, shouting 'Eureka!' ('I have found it!').

When the Romans laid siege to Syracuse he designed catapults and machines to keep them at bay for years. When the Romans finally got into the city, Archimedes was killed by a soldier.

Archimedes studied in Alexandria and would have studied with Euclid's successors

Claudius Ptolemaeus (Ptolemy), astronomer- A model, but not as we know it (c.85 AD to 168 AD)

Greek astronomer who worked in Alexandria

Ptolemy is another ancient about whom we know very little. His name is part Roman (Claudius) and part Egyptian/Greek. So it is thought that his ancestors probably moved from Greece to Alexandria in Egypt. One of them may have been granted Roman citizenship.

However, his work is well known because, by refining the geocentric model of Aristotle, he helped it to last for the next 1350 years. His mathematical model has a stationary earth at the centre with the stars, the Sun, the Moon and the 5 known planets all revolving around it.

His model was far better at predicting planetary positions than anything else produced in antiquity. It was so persuasive that it became the official Christian doctrine and guided all European thinking even after Copernicus suggested the Sun as the centre in around 1500.

His theories are preserved in a 13-volume work known as The Almagest.

Euclid's Elements would have been a standard text for Ptolemy Ptolemy's ideas of a geocentric Universe lasted until Copernicus Ptolemy's work on optics were next picked up by Al-Haytham 400 years later .

Chinese Sun dial - A stick's shadow to track time (c. 2500 BC)

By putting a bamboo stick in the ground and tracking its shadow, the Chinese developed the first recorded example of a timepiece. With it, they could get a good estimate of the time of day.

However, as with many Chinese inventions, it didn't have any influence on the rest of the world. Sundials crop up in a number of places (and were probably developed independently) in around 300 BC

Shih Shen et al - Comets, stars and supernovae (613 BC to 200 BC)

Chinese astronomers observed and recorded many astronomical events including Halley's comet (in 613 BC) and the first recorded supernova (in 352 BC).

In around 300 BC, Shih Shen compiled the first map of the stars. About 200 years earlier, astronomers had recorded comets (referred to as broom stars) in an atlas called The Book of Silk, which was discovered in a tomb in 1976.

Zon Yan - Yin and Yang in science (c. 300 BC)

The ancient Chinese philosophy of Yin and Yang is based on opposites being complementary and yet in conflict. An example is day and night. Many of their features are the exact opposite to each other - light versus dark; warm versus cold. Nevertheless, they complement each other and without night, there would be no such idea as day.

In around 300 BC, the Chinese philosopher Son Yan integrated these ideas into the developing ideas of science - mainly astronomy.

Loadstone compass- What is geomancy? (c. 220 BC)

From early in the first millennium BC, the Greeks, Romans, some Europeans and the Chinese knew of the magnetic properties of loadstone - i.e. that pieces of loadstone would attract and repel each other.

However, unlike the others, the Chinese realised that loadstone magnets all pointed in the same direction. So they had the basis of a primitive compass for geomancy - to ensure that a house was facing in the correct direction - and for guidance.

However, loadstone compasses were not very transportable and it wasn't until more like 200 AD that navigational compasses were first used - again in China.

Compasses with metal needles replaced the early loadstone compasses about 700 years later .

100 AD to 1100 AD

During what was known as The Dark Ages in Europe, the Roman Empire collapsed and disease, chivalry and superstition took over in Europe. However, Chinese thought continued to develop and Islamic culture (beginning c.600) flourished, nurturing the philosophy and mathematics of the Greeks.

Hypatia, Philosopher and mathematician - Famous woman who was murdered (c. 360 AD to 415 AD)

Egyptian philosopher and mathematician born in Egypt and worked in Alexandria.

Hypatia was a thinker, who like Ptolemy, kept the tradition of Greek astronomy alive in Alexandria in the early centuries of the Christian era.

She died violently - probably because, as a pagan, she was blamed for difficulties between the authorities and Christians. She was dragged from her classroom by monks who pelted her to death in the street.

Hypatia was a well known author, inventor and letter writer. She wrote on geometry, algebra and astronomy and invented apparatus for distilling water, an instrument to measure the specific gravity of water, an astrolabe and a planisphere.

She travelled widely and corresponded with people all over the Mediterranean. Letters addressed simply to 'The Philosopher' were delivered to her and today she is regarded as science's first famous woman.

Hypatia would have picked up on Ptolemy's work . Al Khwarrizmi would have studied her work amongst the Greek and Egyptian texts . Ibn Rushd took many of the Greek and Egyptian ideas into Western Europe 600 years later .

Al-Khwarizmi, Persian mathematician - We have algebra thanks to him (c. 780 to 850 AD)

Mohammed al-Khwarizmi gave us the words (and techniques of) algebra and algorithms. He was a scholar at The House of Wisdom in Baghdad and brought together ideas from Babylon, India and Greece.

Two of al-Khwarizmi's most influential books were Al-jabr wa'l Muqabalah, which gave its name to algebra, and Al-Khwarizmi on the Hindu Art of Reckoning, from which we get the word algorithm (based on his name).

He helped bring the idea of zero into mathematics; although a symbol for zero had been introduced by the Babylonians, it was Indian mathematicians who had started using it as a number in the 6th century.

Hypatia's earlier work would have been available to Al-Khwarizmi .

Descartes developed many of Al-Khwarizmi's mathematical ideas 800 years later .

Al-Razi, Doctor and philosopher - First medical user of opium (ca 841 to 926)

Persian doctor, philosopher and thinker from Rayy.

Abu Bakr al-Razi (also known as Rhazes) was born and died in Raay near Tehran.

Al-Razi worked mainly as a doctor. However, as a thinker and writer (of 184 books), he contributed to the understanding of medicine, philosophy, alchemy and chemistry.

He developed Democritus' atomic theory into something that was remarkably close to John Dalton's scheme a thousand years later. However, it was not widely adopted.

He was interested in astronomy and discovered the Andromeda galaxy.

His medical writings greatly influenced the Islamic world as well as Western Europe in the Middle Ages and he is credited with the first uses of alcohol and opium (as an anaesthetic) in medicine.

Al-Razi's atomic theory built on the ideas of Democritus 1200 years earlier After 900 years, John Dalton's atomic theory was, in many respects, similar to Al-Razi's .

Al-Haytham, Persian astronomer and engineer - A man who pretended to be mad (c. 965 to 1040)

Abu Ali al-Haytham was born in Basra in what is now Iraq. While still in Basra, he built up a reputation as an accomplished thinker and, at some point, moved to Alexandria in Egypt.

He worked for the eccentric and dangerous Caliph, Al-Hakim and, according to one story, spent a number of years pretending to be mad to hide from him.

During this time, he wrote about optics and astronomy. His works on optics were the first since Ptolemy's nearly a thousand years earlier.

The last great works on optics were Ptolemy's - 1000 years before Al-Haytham . Al-Haytham's work was taken west by Ibn Rushd .

Al-Biruni, Astronomer and cartogropher - Mapped the curved world onto flat maps (973 to 1048)

Abu Arrayhan al-Biruni was born near the Aral Sea in what is now Uzbekistan. He worked on a way to project the spherical Earth onto flat maps and therefore had a great influence on the traders then travelling between the Arab and Chinese worlds.

By the age of 19, he had measured the latitude of his home town, Kath, using the maximum altitude of the Sun.

Al-Biruni would have heard about Chinese compasses from traders from the Far East . Al-Biruni would have known Ibn-Sina Ibn Rushd took many of these ideas west Like all mathematicians, Al-Biruni would have learned his geometry from the ancient works of Euclid and

Pythagoras.

Ibn-Sina (Avicenna), Arabian physician and philosopher - Wrote 400 books, including an autobiography (981 to 1037)

Arabian physician and philosopher

Abu Ali al-Husain ibn Abdallah ibn Sina is often known by his Latin name, Avicenna. Unlike many of his contemporaries, we know quite a bit about him because he wrote an autobiography.

Ibn-Sina is best known as a physician and his book The Canon of Medicine. However, he wrote over 400 books, with 150 surviving, on philosophy. These include an encyclopedia of logic, geometry and astronomy called The Book of Healing.

Much of his work was to collect and publish existing ideas and bring them to a broader audience. However, he also made contributions to astronomy including showing that Venus is closer to the Sun than the Earth and proposing that the speed of light is finite.

Ibn-Sina would have known Al Biruni Ibn Rushd took many of these ideas west 200 years later .

Ibn Rushd, Moorish physician and philosopher - Was banished and had his books burned (1128 to 1198)

Like Anaxagoras before him and Galileo after, Ibn Rushd was a philosopher who clashed with the religious authorities - this time the Caliph.

Abu'l Waleed Ibn Rushd - also known as Averroes - was born in Cordova (Cordoba) in Spain and studied law and medicine.

His works on Aristotle brought Greek philosophy back into the mainstream and to a wider audience. He is therefore an important figure in the development of Western philosophy as well as Islamic thought.

Despite his assertion that there was no conflict between religion and philosophy, he was banished in 1194 and his philosophical books were burnt. This was on the grounds that Greek philosophy was contrary to Islam.

He was allowed to return to Morocco just before he died.

Ibn Rushd brought many of the ideas from Arab mathematicians to Moorish Spain. Ibn Rushd brought many of the ideas from Arab thinkers to Moorish Spain . Ibn Rushd's work made a lot of the ancient mathematics available to Descartes Ibn Rushd made the ancient works available to Renaissance developers .

Su Song, Chinese mathematician and astronomer - Astronomical clock (c. 1050 to 1100)

Mathematician and astronomer from Bianjing (now Kaifeng in Henan)

In 1088 Su Song, the Chinese Minister of Punishments and expert in the calculation of calendars, designed and built a water driven astronomical clock.

The clock tower was over 10 metres tall and stood in the open. It had three levels that were for astronomical observations, showing the movements of the planets and, using wooden figures, struck the time of day.

It was the most advanced astronomical instrument of its day. According to contemporary records, its precision was such that it was said to have 'measured time as exactly as the sundial'.

After a number of failed attempts, historians have recently managed to build a working replica at the National Museum of Natural Science in China.

Fire arrows - Gunpowder rockets (c. 1200 AD)

Chinese alchemists had known for over a thousand years that sulphur and saltpeter were useful for starting fires. Sometime in the 8th century, they found that combining them with charcoal produced a fiery substance that they called huoyao and we call gunpowder.

At some point they realised that they could unnerve their enemies if they packed the gunpowder into bamboo tubes and launched them on an arrow - like a rocket.

Their first recorded use was in 1232 during the war with the Mongols, who produced their own rockets later and probably brought them (and gunpowder) west to Europe. Da Vinci would have been intrigued by these rockets.

Compass for navigation - The magic of metal needles (c. 200 to 1100 AD)

The Chinese had been using loadstone from early in the first millennium BC. However, it is not practical for a navigational compass because it is so bulky.

In around 200 AD, they developed compasses with iron needles. By heating the needle and letting it cool lying north-south, it becomes magnetised.

However, it wasn't until about 1100 AD that Chinese sailors used compasses for complex navigation. It is thought that Arab traders probably learned the skill from them some time in the 12th century. They then brought the practice to the Western world.

Traders would have taken this knowledge westwards to the likes of Al Biruni .

1400 to 1680

The Renaissance - or rebirth - began in Italy and saw the ideas of The Greeks returning to Europe. The message spread northwards and explorers spread west to cover the globe. Within 300 years through religious and civil conflicts, natural philosophers had rewritten the Ancient foundations and tools of philosophy.

Leonardo da Vinci, Renaissance man- Left handed mirror writer! (1452 to 1519)

Renaissance man born in Florence

In his lifetime, Leonardo da Vinci was primarily an artist, living off commissions and patronage from the rich and powerful. However, he was also an inventive designer- though none of his 'inventions' was ever built. In the fields of anatomy, optics and hydraulics, he anticipated many of the developments of modern science - he even designed a workable flying machine.

His scientific theories, like his artistic innovations, were based on careful observation and precise documentation. His notebooks were written in mirror script - either to keep them secret or because he was left handed.

This may have contributed to the fact that no-one really knew of his findings in his own lifetime; had they been published, they would have been of great interest to engineers and designers in the 16th and following centuries.

Ibn Rushd brought many of the Ancient philosophies to the west Fifty years later, Galileo followed the Renaissance thinkers like da Vinci

Nikolas Kopernig (Copernicus), astronomer – Did he change the Universe? (1473 to 1543)

Astronomer born in Thorn (now Torun), Poland.

Nikolas Kopernig – usually known by his Latin writing name, Nicolaus Copernicus – is best known for his heliocentric theory of the Universe. This updated and, eventually, replaced Ptolemy’s ideas, which were showing their age (they had lasted for about 1500 years – not bad as theories go).

In his work On the Revolutions of the Celestial Spheres, Copernicus proposed that the Sun is at the centre of the Universe; the planets, including the earth, revolve around it.

However, this defied the teachings of the Church and his books were heavily censored or even banned by the Vatican.

Nevertheless, most astronomers still used his techniques – but only as a means of calculating planetary positions and not as a representation of reality. For this, they stuck with the church-approved views of Aristotle. It was another 100 years before astronomers began to accept his ideas as true.

Ptolemy’s geocentric model had lasted for 1500 years until Copernicus The works of the Greeks, like Anaxagoras, would have been foundations for Copernicus Galileo was one of the first people to affirm Copernicus’ ideas

Tycho Brahe, astronomer – Why did he have a metal nose? (1546 to 1601)

Danish astronomer, born in Knudstrup in southern Sweden (then part of Denmark).

Tycho Brahe is (and was) famous for his comprehensive astronomical measurements. His data exceeded all the existing astronomical measurements and were only bettered by the invention of the telescope early in the 17th century. They were vital for the work of Kepler.

However, he was also well known as an eccentric and a tyrant. As a child, he was kidnapped by his Uncle (after his father reneged on a promise to hand over his first born if it was a boy). As a young man he had part of his nose cut off in a duel following an argument over who was the better mathematician; he wore a metal nose for the rest of his life (it may have been silver or brass). And, as an older man, having been given an island (and its inhabitants) by the King of Denmark, he abused his tenants mercilessly.

Tycho’s observations of the new star of 1572 and comet of 1577, proved that these bodies were above the Moon and that the planets could not be carried on Aristotle’s spherical shells because comets would have to move through these spheres.

The works of the Greeks, like Anaxagoras, would have been foundations for Brahe Kepler used Brahe’s observations to derive his laws

Sophia Brahe, Danish astronomer and historian – A legend in her own lifetime (1556 to 1643)

Sophia was the younger sister of Tycho Brahe and assisted him with his astronomical observations. Sophia made her own career as a horticulturist, healer, historian and astronomer. Like Tycho, she became a legend in her own lifetime. Even today, some European universities use her chronicles as an exemplar of methodology in research techniques.

She worked with her brother, Tycho Brahe

Galileo Galilei, mathematician and astronomer – Was he a hero or a heretic? (1564 to 1642)

Mathematician and astronomer born in Pisa, Italy.

In 1609 Galileo built a telescope and looked into the sky. With it, he was able to observe mountains and craters on the Moon, the moons of Jupiter, and the phases of Venus.

Although telescopes were already being used, he was the first person to point it at the heavens – which were still thought as being separate and more ordered from the Earth. Previously, telescopes were used for terrestrial activities like navigation, communication and controlling ships in harbour.

In his Dialogue Concerning the Two Chief World Systems, Galileo attacked Greek cosmology and defended the Copernican system with the Sun at the centre of the solar system.

Galileo was condemned by the Catholic Church for his views which were considered heresy. He was tried by the Inquisition and sentenced to spend the last years of his life under house arrest.

Much is made of his run in with the Catholic Church and the fact that the Vatican took until 1993 to officially recognise the validity of his work. However, it is most likely that he fell foul of local politics with cardinals rather than being in direct conflict with the Church. Indeed, Jesuit priests were carrying out experiments through the 16th and 17th centuries.

He made experimentation fashionable and, by dropping objects from the Leaning Tower of Pisa, showed that objects fall at the same rate. His work on the periods of pendulums – inspired by a swinging chandelier in the cathedral – were another example of how experimentation could reveal new ideas. He also conducted thought experiments about forces and dynamics and his work was to influence Isaac Newton, who was born in the year of his death.

Galileo was one of the first people to put his faith in Copernicus’ model Newton, who was born in the year of his death, built on Galileo’s ideas .

William Gilbert, natural philosopher and doctor – What is the angle of dip? (1544 to 1603)

English natural philosopher and doctor born in Colchester, England.

William Gilbert was a natural philosopher and physician – to Elizabeth I, no less. We remember him primarily for his experiments into the nature of magnetism.

Although compasses had been used for many centuries, no-one understood how they worked. Some thought it was an attraction to the Pole star; others thought that the North Pole was home to a mysterious range of iron capped mountains that would rip the nails out of any ship that ventured too close. There was even a theory that garlic affected compasses – which meant that helmsmen were forbidden from eating it.

Anyway, Gilbert showed that a compass swings north because the Earth is a giant magnet. Also, based on the work of Robert Norman – a compass maker – he showed that a compass needle pointed downwards as well as northwards. We now know this as the dip of the Earth’s field – although the idea of a field is much more recent.

He also believed that the planets were held in orbit by magnetic forces – an idea that Kepler followed as well.

Gilbert was the first to use the terms electric force, electric attraction and magnetic pole.

Gilbert revived the ideas of Thales and took the Greek word elektron Von Guericke developed many of Gilbert’s electrostatic ideas Like Kepler, Gilbert thought the planets were held in orbit by magnetism

Johannes Kepler, German astronomer – Laws of planetary motion (1571 to 1630)

Astronomer and natural philosopher, born in Weil-der-Stadt, Germany.

Johannes Kepler, a contemporary of Galileo, corresponded with and. for a short time, worked for the astronomer Tycho Brahe.

Unlike Brahe, Kepler accepted the Copernican (Sun-centered) theory of the Universe. He used Brahe’s extensive and precise data to show that the orbits of the planets are not circles but “flattened circles” or ellipses.

His three laws became very well established and a yardstick by which future theories would be judged. Isaac Newton relied heavily on them to validate his inverse square law of gravity.

Kepler used the fine observations of Brahe to develop his laws of planetry motion By explaining Kepler’s laws, Newton added weight to his theories Like Gilbert, Kepler thought the planets were held in orbit by magnetism

René Descartes, French philosopher and mathematician – Scientific reason and x,y co-ordinates (1596 to 1650)

Philosopher and mathematician born in La Haye, France.

Descartes is often called the father of modern science. His revolutionary Discourse on Method proposes the use of reason to search for the truth.

He rejected all ideas based on assumptions or emotions and even removed his own existence from what could be assumed. However, given that he was able to think about whether or not he existed, he deduced that he must. Hence his statement “Cogito ergo sum” – I think, therefore I am.

He proposed the idea of a clockwork Universe: having been set in motion by God, everything follows mechanical laws and the Universe unwinds fatalistically like a clockwork toy. Unlike Newton, Descartes didn’t accept that forces could act without contact; so his Universe is full – everything is touching something else – sometimes via an ether, though his ether was different from Newton’s.

From his name, we get the adjective cartesian. This describes the system of x,y,z axes and positions (Cartesian coordinates) and the diving balloon in a sealed jar of water (Cartesian diver).

It also describes his followers, the Cartesians, who (like the Newtonians later) had a long running dispute with Leibniz. In this case about motion and force (what we call momentum).

Descartes, like other Renaissance mathematicians, worked on the ideas of the Greeks like Thales Michelson showed there wasn’t an ether in 1887 Heisenberg’s uncertainly principal ended all ideas of a clockwork Universe Ibn Rushd had made the works of the Ancients available to The Renaissance Newton took on some of Descartes ideas Descartes’ followers had disputes with Leibniz

Otto von Guericke, German natural philosopher – Pressures, vacuums and static electricity generator (1602 to 1686)

Natural philosopher born in Magdeburg.

Like many well known experimenters of his day, Otto von Guericke had the good fortune to be born into an aristocratic family and therefore have the time and funding to follow his scientific interests.

In 1672, von Guericke developed the first generator that could produce an electric charge. He also invented an air pump. With this he stunned an audience by making the Magdeburg hemispheres that could not be pulled apart by two teams of eight horses.

The hemispheres showed the strength of atmospheric pressure and also that it was not impossible to create a vacuum – a view that had been held up to then by, for example, Descartes and Aristotle.

Von Guericke built on the earlier work of William Gilbert Franklin took up von Guericke’s ideas on electricity Galvani used von Guericke’s methods to generate static electricity

Robert Hooke, English natural philosopher – Elastic properties, astronomy and light theory (1635 to 1703)

Natural philosopher born on the Isle of Wight

Robert Hooke was an architect and surveyor for the City of London after the Great Fire. He was also an extremely accomplished natural philosopher who had wide ranging experimental skills and invented many instruments.

There are those who, probably fairly, think that Hooke had a raw deal in life and in posterity. In his day, he was prolific and accomplished, yet he is remembered mostly for just the one law (on elasticity) and his feud with Newton.

Hooke was born 7 years before Newton on the Isle of Wight and was orphaned at 13 when his father hanged himself. By then, he had also survived smallpox, which had left him badly disfigured. Later, there were those, including his niece (with whom he was besotted and had an affair), who avoided him because he was so ugly.

Being seven years older than Newton, he was well established at the Royal Society by the time Newton submitted his paper on light. Hooke opposed Newton’s ideas and the animosity between the two men continued on and off until Hooke’s death 24 years before Newton. By then, Newton was President of the Royal Society and was able to promote his own side of their feud at Hooke’s expense.

Hooke followed Galileo’s ideas on mechanics Hooke tried to derive Kepler’s laws from an inverse square law of gravitation Hooke feuded with Newton for many years Halley worked with Hooke

Isaac Newton, English mathematician and natural philosopher – Laws of motion, gravitation and theories on light and calculus (1642 to 1727)

Mathematician and natural philosopher, born in Woolsthorpe, Lincolnshire

Isaac Newton was born in the year that Galileo died and is often seen as his successor. He had a colossal intellect and, in his early adulthood, an unstoppable drive to understand everything.

Newton’s working life has two distinct halves – as a reclusive, eccentric, academic in Cambridge and as a wealthy, influential and famous philosopher in London. He had long running feuds with Leibniz and Hooke. The first was over who had been the first to develop the methods of calculus; the second was over all sorts of things – it probably started when Hooke objected to a paper Newton wrote on light.

His greatest works – Opticks and Philosophiae naturalis principia mathematica – originated from his time at Cambridge. The ‘Principia’ is the masterwork that provided, in a mathematical way, the framework for understanding forces and motion. As well as containing his laws of motion it took, for the first time, physics into the heavens with his universal law of gravitation. Previously, the celestial arena had been thought of having separate laws from those on Earth. It was Newton who proposed that the same force (gravity) holds the Moon in orbit and us on the ground.

According to legend, Newton began thinking about universal gravitation when he saw an apple fall from a tree in his Lincolnshire orchard – where he had returned to avoid the plague in Cambridge. On returning to Cambridge in 1666, he developed pages of notes on the subject but didn’t show anyone. Nearly 20 years later, Halley visited Newton after a bet with Hooke over who could derive Kepler’s laws from a law of gravitation. Newton gave Halley the answer and the proof almost instantly.

Halley persuaded Newton to publish his findings. He even paid for the publication after the Royal Society withdrew funds. Principia was first published in 1687.

Nine years later, after some nervous breakdowns, Newton moved to London and spent the last 28 years of his life as Master of the Mint. He lived comfortably and well and, as President of the Royal Society, strongly influenced further research.

Newton formalised and explained many of Galileo’s ideas Newton used an inverse square law of gravitation to derive Kepler’s laws Newton feuded with Hooke for many years Halley brought Hooke’s challenge to him Newton fell out with Leibniz over the priority of calculus Newton’s analysis of the Universe was unchanged until Einstein in 1905

Gottfried von Leibniz, German mathematician – Developed calculus and other mathematical methods (1646 to 1716 )

Mathematician and philosopher born in Leipzig, Germany.

He developed (independently from Isaac Newton) a new kind of mathematics known as calculus. However, there was (and is) a long running dispute over who was the first to come up with the ideas. The two men exchanged a number of letters that vary in tone but, even when polite, show the distrust between them.

He made original contributions to optics, mechanics, statistics, logic, and probability theory and conceived the idea of calculating machines.

Whoever got there first, it is Leibniz’s methods that we use today. Newton claimed that he wrote the ‘Principia’ using his calculus and converted this to geometry so as to publish it in the language of The Ancients. So, despite its huge influence, the ‘Principia’ did not bring calculus into natural philosophy. On the other hand, the German mathematician Leonhard Euler developed Leibniz’s calculus which then spread to France about a hundred years later. It arrived in the UK in the early 1800s.

As a mathematician, von Leibniz built on the methods of Descartes, despite a dispute with his followers Von Leibniz had much in common with Newton, despite their long running priority dispute

Edmond Halley, English astronomer and mathematician – Halley’s comet and work in magnetism (1656 to 1742)

Astronomer and mathematician born in London.

Edmond Halley went to University in Oxford and worked with Robert Hooke and Christopher Wren. It was Wren who challenged the other two men to explain elliptical orbits from a law of gravitation. Halley, possibly becoming fed up with Hooke’s boasting, visited Newton in Cambridge to ask his advice.

However, as well as being the instigator and funder of Newton’s Principia, Halley made many contributions of his own. He published many articles and produced the first meteorological map that showed prevailing winds around the world.

His magnetic theories – which included the ideas of the Earth having a moving inner core and wandering poles – were important for well over a hundred years.

He showed that some comets have elliptical orbits and that the comets seen in 1531, 1607 and 1682 were in fact the same one. It is now known as Halley’s comet, although he was not the first to see it.

Halley influenced Newton’s rise to prominence Halley worked with Hooke at the Royal Society The comet that takes Halley’s name had been seen in Ancient China Olber developed many of Halley’s ideas on the Universe

1700 to 1840

During this time, revolutions in America and France affected the cultural outlook of these (and other) nations. Invention and experimentation became respectable and natural philosophy was quickly developing into physics in the wake of its first heroes from The Renaissance.

Benjamin Franklin , experimenter/inventor – Invented bifocals and shocking kite (1706 to 1790)

American inventor born in Boston, America.

Benjamin Franklin was a newspaper editor, diplomat, philosopher and inventor. He ran away from his tyrannical brother when he was seventeen and ended up in Philadelphia. There he set up a print shop and, eventually, bought his own newspaper.

Franklin’s publishing business thrived and he could indulge his interest in science, carrying out the famous (and dangerous) kite experiment. He hung a key on the end of a kite’s string and flew the kite into a thundercloud whilst wearing a silk glove for protection!. His experiment showed that lightning was a kind of electricity. The next two people to try this experiment were electrocuted!

He explained static electricity as a single fluid that could appear both positive and negative. As a businessman, he made an analogy with a bank account that can be in the black or in the red. Before him, people thought that there were two types of static electricity.

He also invented bifocals, the odometer, the Lightning Rod and the Franklin stove, for which he didn’t take out a patent because he felt the device was for public good.

In 1757, he travelled to England to represent Pennsylvania (then an English colony) in its battle with the Penn family. Although at the time he was a loyal (English) subject, his views changed whilst he was in England and by 1776 he was helping to draw up the Declaration of Independence and the Constitution of the United States.

Franklin built on Von Guericke’s ideas on electricity Volta worked on electricity at about the same time as Franklin . Coulomb developed electrical ideas at about the same time as Franklin . Faraday was born the year after Franklin died and combined electrical ideas with magnetism . Henry combined theories on electricity with magnetism .

Count Alessandro Volta, physicist – Invented the voltaic pile (1745 to 1827)

Physicist born in Como, Italy

Alessandro Volta is known for his pioneering work in electricity.

In 1775 he devised the electrophorus, an instrument that produced static electricity by friction. Stimulated by Luigi Galvani’s discovery of animal electricity in 1786, Volta piled up little discs made from different metals in a salt solution to produce a continuous flow of electricity. By 1800 he had developed the so-called voltaic pile, a forerunner of the electric battery.

Galvani and Volta disagreed passionately about whether the electricities they produced were the same. Galvani held that his animal electricity was different from Volta’s electricity and Volta believed they were the same – as we do now.

In honour of his work in the field of electricity, Napoleon made him a count in 1801.

The electrical unit, the volt was named after him.Volta picked up ideas and electrostatic techniques from Von GuerickeVolta was inspired by Galvani’s work but disagreed with his ideas.

Faraday took forward many of Volta’s early ideas on electricity. Ohm developed some of Volta’s ideas. Henry combined Volta’s electrical ideas with magnetism.

Luigi Galvani, physiologist- Famous for twitching frogs (1737 to 1798)

Physiologist, born in Bologna, Italy

Luigi Galvani is noted for his studies of the effects of electricity on animal nerves and muscles. He discovered, accidentally, that two different metals could produce what he called ‘animal electricity’. It may be that he elaborated the accidental aspect of the discovery to make a better story.

However, the story is that he was doing some experiments on dissected frogs’ legs – making them twitch using static electricity (or ‘artifical electricity’ as he called it). During an experiment, his assistant (probably his wife) touched a nerve with a metal scalpel while a frog’s leg was hanging on a brass hook.

These findings led Volta to the invention of the voltaic pile, the world’s first battery. Galvani’s name is still associated with electricity in the words galvanometer, galvanism and galvanization.

Galvani used static electricity generators like those of Von Guericke Volta was inspired by Galvani’s work but they disputed the interpretations

Marquis Pierre de Laplace, mathematician – Kept his head for nebular theories (1749 to 1827)

Astronomer and mathematician, born in Normandy, France.

Pierre de Laplace’s deftness and pragmatic politics meant he was spared during the Reign of Terror which claimed, amongst many others, Lavoisier.

In 1796, he published Exposition du systeme du monde in which he proposed a nebular theory for the formation of the Sun and Earth – i.e. that a cloud of matter contracted to form the stars and planets. His general idea is still accepted today.

Later he published methods that used differential equations and probability theory to apply Newton’s theory of gravitation to explain planetary motion.

Laplace called himself the ‘French Newton’ and it is his model of the Universe rather than Newton’s that we usually associate with Newton. Newton’s Universe required God’s intervention (through comets); whereas Laplace’s did not. Napolean, on seeing his description accused Laplace of eliminating God from the Universe. “Sire” he replied “I have no need of that hypothesis”.

Laplace called himself the ‘French Newton’ and worked with many of his ideas Like Descartes, Laplace had a theory of a clockwork Universe Laplace helped bring the calculus of Leibniz into mainstream mathematics Foucault was the next great French mathematician

Charles Coulomb, physicist – Did he really get those results? (1736 to 1806)

Physicist, born in Angoulème, France.

Charles Coulomb is another French experimenter and man of science who survived the Reign of Terror. Afterwards, he was summoned to Paris and helped to devise the metric system of weights and measures.

He invented the torsion balance for measuring the small forces between electrically charged particles and magnetic poles. With this invention, he was able to formulate Coulomb’s law, describing the force between electric charges. His law is remarkably similar to Newton’s law of gravitation and he was strongly influenced by Newton’s work.

Given the difficulty in obtaining accurate results – even with his torsion balance – it is likely that he knew what he was looking for when he began the experiment. He may even have cheated a bit!

The unit of electrical charge, the coulomb, was named after him

Coulomb used machines like Von Guericke’s to generate static electricity Coulomb would have worked with the other French physicists like Volta Coulomb developed some of Franklin’s ideas on electricity

John Dalton, chemist – A teacher at 12 years old (1766 to 1844)

Chemist born in Eaglesfield, Cumberland (now Cumbria), England

John Dalton is best known for his contributions to atomic theory but he also identified the phenomenon of colour blindness, an affliction that he shared with his brother. He was a prodigy and became a teacher at his local school when he was just 12.

In his New System of Chemical Philosophy (1808), he proposed the idea of tiny particles or atoms which could not be created or destroyed. He also developed the techniques of atomic weights and formulae.

Many of his ideas were widely taken up, although many scientists rejected his notion that matter was made up of hard, indivisible atoms.

Gradually, like most scientific innovations, atomism became generally accepted.

Dalton’s atomic theory was very close to an ancient one proposed by Al Razi The Greek philosopher Democritus had given us early ideas on atoms At one time Dalton taught James Joule and his ideas on atoms were key to the statistics of Kelvin and Maxwell

André Ampère, physicist – Forces on electric currents (1775 to 1836)

Physicist and mathematician born in Polemieux-au-Mont-d’Or, France

Ampère is best known for his contributions to the study of electrodynamics and electromagnetism. In 1826, he proposed Ampère’s law which describes mathematically the magnetic force between two electric currents.

He performed many experiments that allowed him to explain known electromagnetic effects and predict new ones as well.

He invented a galvanometer, an instrument that uses a freely moving needle for detecting and measuring electric currents.

The ampere (amp), the unit of electric current, is named after him.

Ampère’s theories on current relied on Coulomb’s charges Ampère developed ideas on current flow Volta Ampère and Ohm were aware of each other’s work Faraday picked up many of Ampère’s ideas on currents and magnetic fields Joseph Henry developed Ampère’s ideas on magnetic fields and currents Ampère’s law is one of the laws that Maxwell formalised into his famous equations

Heinrich Olber, astronomer – Olber’s paradox on starlight (1758 to 1840)

German astronomer born in Abergen (now part of Bremen).

Heinrich Olber discovered several comets and asteroids. He devised a method, still employed by astronomers, for calculating the orbits of comets.

In 1826, he wrote an important paper on a problem that had been noted by previous thinkers, namely why the sky is dark at night. The essence of the puzzle is that if the universe were infinitely big and full of stars, then in every direction we look the line of sight should end on a star, and the whole sky would be uniformly illuminated.

This observation, called Olber’s paradox, has been resolved with the discovery that the observable universe has only a limited extent – probably no greater than 20 billion light years’ radius.

Olber used methods of Newton and Halley to calculate orbits

Olber took forward Laplace’s ideas on the Universe It was the work of Edwin Hubble that finally helped resolve Olber’s paradox

Georg Ohm, physicist – Liked the good life and gave us Ohm’s Law (1787 to 1854)

German physicist, born in Erlangen,

Georg Ohm learnt his science and mathematics from his self-taught father, Johann. When he finally went to school (or Gymnasium), there was little in the way of inspiration or science.

He went to university but his father removed him after a year because Georg used the opportunity to carouse rather than learn. He took up a teaching job and, now more mature and a little chastened, continued his own research and reading.

Ohm is best known for his work on electric currents. He defined electrical resistance in the relationship V=IR and gave his name to the unit of electrical resistance (which has to use the Greek symbol omega as an ‘O’ would be very confusing!).

Ohm developed the work of Volta Ohm and Ampère were familiar with each others’ work Faraday and Ohm were working in the same field Kirchoff used Ohm’s equation to derive his own laws on circuits

Michael Faraday, physicist – Working class boy made good (1791 to 1867)

Physicist born in Newington, Surrey.

Michael Faraday was an apprentice bookbinder and the son of a blacksmith and although he received little formal education, in 1812 he obtained a job as a scientific assistant to Sir Humphry Davy at the Royal Institution.

He had been inspired by the book Conversations on Chemistry by Jane Marcet and started going to Davy’s lectures. In turn, he wrote them into a book which he bound by hand and presented to Davy. Davy was so impressed that he gave him a job at the Royal Institution.

In 1831 Faraday and the American Joseph Henry independently discovered the phenomenon of electromagnetic induction now known as Faraday’s Law.

In 1845 Faraday discovered the magnetic rotation of light (Faraday rotation) and speculated that light might be electromagnetic in nature. He thought it might be transverse vibrations of his field lines. He also suggested that light and electricity may be different manifestations of the same force.

He investigated the phenomena of electrolysis and developed the laws of electrolysis.

He is credited with building the first electrical transformer and the electric dynamo. His work led directly to the development of electrical machinery for industry.

Faraday developed and relied on the work of Ampère Lenz formalised and refined Faraday’s ideas on electromagnetic induction Faraday and Ohm would have been familiar with each others’ work Henry independently discovered the same laws of electromagnetic induction but failed to publish them Faraday would have relied on work by Volta on electricity Maxwell’s equations take in Faraday’s law on electromagnetic induction

Joseph Henry, physicist – Tried watchmaking, acting, teaching and… (1797 to 1878)

Physicist, born in Albany, New York.

Joseph Henry was a reserved and quiet man from an ordinary background – his father was a New York labourer. At thirteen, he became a watchmaker’s apprentice and, as a young man, almost became an actor. However, friends persuaded him to take a place at the Albany Academy.

Whilst he was a schoolteacher, he discovered the principle of electromagnetic induction – before the British physicist Michael Faraday. But Faraday published his findings first and is credited with the discovery. However, Henry also deduced the idea of self inductance and gave his name to its unit.

In 1831, Henry constructed the first practical electromagnetic telegraph and devised and constructed one of the first electric motors. His ideas led directly to the work of Morse and Bell in telecommunications.

Henry developed and relied on the work of Ampère Lenz formalised some of Henry’s ideas on electromagnetic induction Henry’s ideas on inductance took Ohm’s theories to a higher level Henry independently discovered the same law as Faraday but failed to publish before him Volta’s work would have been the basis of much of Henry’s own

Heinrich Lenz, physicist – World traveller and physicist (1804 to 1865)

Russian physicist born in Dorpat (now Tartu) Estonia

Heinrich Lenz had travelled the world by the time he formulated his law. He was a geophysicist who had been on a three year trip around the globe when he took up a post at St Petersberg.

Here Lenz studied electromagnetism and induction and devised his law for determining the direction of Faraday’s induced currents. Lenz also studied the heating effects of an electric current and, independently of English physicist James Joule, came up with the law now known as Joule’s law.

Lenz formalised the ideas of Farady’s law Lenz developed Henry’s ideas along with those of Faraday Maxwell included Lenz’s law into his famous set of equations

Gustav Kirchhoff, physicist – Ruined his eyesight for his work (1824 to 1887)

German physicist born in Konigsberg (now Kaliningrad) Russia.

Gustav Kirchoff suffered for his science by staring for too long at the Sun.

With the German chemist Robert Bunsen, Kirchhoff developed the modern spectroscope for chemical analysis. He used it to examine the Sun’s spectrum, identifying its dark spectral lines – but also ruining his eyesight. Bunsen had a safer time discovering the elements caesium and rubidium in 1860.

Kirchhoff showed that alternating currents (or signals) in wires are carried at the speed of light. This was one of the theories picked up by Maxwell in the 1890s.

He is mainly remembered for his laws on black body radiation and, for those who like simultaneous equations, his laws for analysing circuits.

Kirchhoff used Ohm’s equations to develop his laws of circuits . Maxwell worked on black body radiation . Mendeleev would have used Kirchhoff’s observations * of elements and spectra . Planck used packets of radiation to explain black body radiation .

1840 to 1890

This was the age of steam ships, trains and machinery. International trade increased and there was an incentive to understand and improve the technologies of the age. Scientists (as they were now called) felt that they would soon be able to understand all of nature.

James Joule, physicist – Took his work on honeymoon (1818 to 1889)

Physicist born in Salford, Lancashire, England

As the son of a wealthy brewery owner, James Joule and his brothers were privately tutored – at one time by John Dalton.

When James and his brother took over the family brewery, he set up a laboratory at home. He was a devout Christian and believed that an understanding of nature would bring him closer to his God.

He investigated the heating effects of an electric current and was determined to show that things could also be heated through mechanical work. He eventually succeeded using some water paddles that repeatedly raised and dropped the water.

However, on his honeymoon, he failed to measure a temperature difference between the top and bottom of the waterfall at Chamonix.

His work on electrical and mechanical heating effects led to the theory of conservation of energy – the First Law of Thermodynamics. The unit of energy, the joule, is named after him.

Together with the physicist William Thomson (later Baron Kelvin), Joule found that gases cool when they expand – the principle behind the refrigerator.

As a schoolboy, Joule was taught by John Dalton . Joule developed ideas on electrical heating based on work by Ohm and others . Joule worked with Lord Kelvin on theories about heating .

Jean Foucault, physicist – Invented the gyroscope (1819 to 1868)

Physicist, born in Paris

Jean Foucault was famous for working on the effects of the rotating Earth, inventing the gyroscope. In 1851 he gave a spectacular demonstration to show the Earth’s rotation by suspending a pendulum on a long wire from the dome of the Pantheon in Paris.

He worked with the French physicist Armand Fizeau in measuring the speed of light in air and water

Foucault would have studied the work of his French predecessor Laplace Michelson was the next to develop theories on the movement of the Earth

William Thomson (Baron Kelvin), physicist – A prodigy who spanned two centuries (1824 to 1907)

Mathematician and physicist born in Belfast, Ireland.

From the age of 10, William Thomson (later Baron Kelvin of Largs) attended Glasgow University, where his father was chair of mathematics. When he was 16, he went to Cambridge and by the age of 24 had proposed the absolute scale of temperature that still bears his (lordly) name.

Like many of his contemporaries, Thomson thought that Physics was more or less a complete science. In his words: “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.”

As well as his hugely important theoretical work, Thomson invented a marine compass and a boosting device that allowed telegrams to be sent across oceans.

Dalton’s theory of atoms was essential to Kelvin’s work on thermodynamics . Kelvin worked with Joule on the ideas of heating and work . Maxwell used Kelvin’s ideas in his statistical analysis of temperature .

James Clerk Maxwell, physicist – Prodigious inventor who marked end of epoch (1831 to 1879)

Mathematician and physicist born in Edinburgh, Scotland.

James Clerk Maxwell was a prodigious scientist and investigator. Apparently, at the age of three, he constantly repeated “Show me how it doos”.

By the age of 14, he had written a paper on ellipses and curves that was read to the Royal Society of Edinburgh.

His greatest work was to fundamentally change our view of reality, so much so that Albert Einstein said, “One scientific epoch ended and another began with James Clerk Maxwell”. This was the expression of all the existing laws of electromagnetism in four differential equations.

These exemplify the holy grail of Physics – a self consistent, powerful theory that can be written in four lines of mathematics.

This theory predicted the existence of electromagnetic waves and provided the tools to create the technological age, from radio to mobile phones.

Maxwell relied on Dalton’s atomic theory for his statistics and Faraday’s law for his set of equations Kelvin’s work on temperature was essential for Maxwell’s statistical analysis . Maxwell developed Joule’s ideas on energy in a statistical way . Hertz developed Maxwell’s equations into a practical demonstration of radio waves . Preserving Maxwell’s equations was a measure of the success of Lorentz’s transforms – used by Einstein . When Bose made an error using Maxwell’s statistics, he developed a whole new class of particle with its own statistics .

Thomas Edison, inventor – Light bulb, gramophone and electric chair (1847 to 1931)

Inventor born in Milan, Ohio.

Although he attended school for only three months, Thomas Edison patented more than 1,000 inventions including the light bulb, the fuse and the Edison battery. Invention and inventors were held in higher esteem in the USA than in Europe, where pure science was admired more.

Edison saw himself as the all American businessmen and entrepreneur. His drive to be top dog led, in 1890, to the first (and one of the most prolonged) killings in an electric chair.

The story started 12 years earlier when Nicola Tesla came to work for Edison. Gradually the men’s personalities and adherence to direct (Edison) and alternating (Tesla) currents drove them apart.

Edison, with his d.c. systems, was determined to discredit a.c.. He arranged for a convicted axe murderer to be put to death by electrocution – using a.c., of course. The sentence was carried out in an ‘electric chair’ in August 1890. Then Edison’s propagandists got to work – they used slogans like “Would you like your wife to be cooking with a.c.?”.

His legacies – vacuum tubes, electric lights, the gramophone and the electric chair – live on.

Edison followed in Franklin’s tradition of American inventor Edison developed Faraday’s theories into practical applications . Edison had a long running feud with Tesla .

Albert Michelson, physicist – Astounding ethereal result (1852 to 1931)

Polish American physicist born in Strelno (now Strzelno, Poland).

In 1887 Albert Michelson, funded by Alexander Graham Bell, inventor of the telephone, developed the interferometer. Together with the American chemist Edward Morley he used the interferometer to measure the speed of light with great precision.

At that time, most scientists believed that light travelled as waves through the ether, a substance that filled the universe. They also believed that the Earth travelled through the ether. The Michelson-Morley experiment measured the Earth’s velocity through the ether, and found it to be zero. This proved that the ether does not exist! (By now, the ether was very different from those of Descartes and Newton).

Eight years later, Einstein’s Special Theory of Relativity explained this surprising result, giving weight to his revolutionary theory.

Michelson’s result on the speed of light was key to Einstein’s theories of Relativity Michelson’s results showed that there wasn’t an ether – as thought by Descartes and others . Michelson developed ideas on the motion of the Earth from those of Foucault With Maxwell’s equations, Michelson’s work led to the idea of electromagnetic waves in free space .

Nikola Tesla, inventor – Alternating battles with Edison (1856 to 1943)

Serbian American electrical engineer and inventor born in Smiljan.

Nikola Tesla was an electrical engineer, a poet and an inventor with a sharp and detailed imagination. He grew up and studied in Serbia but, having conceived the idea of an a.c. induction motor, headed for America in 1884. He arrived with four cents and a few poems in his pocket and was employed, for a brief period, by Thomas Edison.

The two men had very different outlooks and soon parted on unfriendly terms. Edison sold his patents for an a.c. system to Thomas Westinghouse.

In 1893, Tesla and Edison competed to supply Niagara Falls with hydroelectric power generators. Tesla’s system won because Edison’s direct current system was unable to distribute power efficiently for more than a few miles. By now, Edison had used his infamous electric chair to try to discredit Tesla’s a.c. systems.

Tesla also worked with radio-frequency electromagnetic waves, and despite the claims made by Marconi, actually did invent the idea of radio as we know it today. When Tesla died in 1943 he held over 700 patents.

Tesla’s work on a.c. relied on Faraday’s law Tesla developed ideas on inductance and coils from the work of Joseph Henry Tesla and Hertz both worked with alternating currents and waves . Tesla had a long running feud with Edison .

Heinrich Hertz, physicist – Died young but still gave us radio waves (1857 to 1894)

Physicist, born in Hamburg.

Heinrich Hertz was a talented Physicist who may have gone on to even greater things had he not died young.

He adapted Maxwell’s Equations in the light of Michelson’s early experiments (that showed that there probably wasn’t an ether). He made the equations more symmetrical.

He demonstrated that electromagnetic radio waves (predicted by Maxwell) could travel through the air. His experiments (well before Marconi) led to the development of the wireless telegraph and radio.

The unit of frequency, one cycle per second, was named the hertz (Hz) after him.

Like Tesla, Hertz worked with a.c. and waves . Hertz used Maxwell’s equations to predict and produce electromagnetic waves The speed of light and electromagnetic waves were a part of Einstein’s theories of relativity . Hallwachs was one of Hertz’s pupils .

Wilhelm Hallwachs, physicist – Strange experiment which Einstein explained later (1859 to 1922 )

Physicist, born in Darmstadt, Germany

Hallwachs was a pupil of Heinrich Hertz. He noticed that shining ultra violet radiation on some metals allowed them to discharge an electroscope.

This property, the photoelectric effect, could not be explained at the time. It needed to wait for J. J. Thomson to discover the electron and then for Albert Einstein to put his mind to it in the early 1900s.

Today the photoelectric effect is used in many devices including light detectors and solar cells

Hallwachs was a pupil of Hertz Einstein explained Hallwachs’ photoelectric effect in one of his three famous papers of 1905 . J J Thomson’s discovery of the electron helped explain the photoelectric effect .

Dmitri Mendeleev, chemist – Political activist and table maker (1834 to 1907)

Russian chemist, born in Tobolsk, Siberia

Dmitri Mendeleev was the youngest of fourteen children. Although his father died when he was young, his mother was determined to give him a good education and get him to University. She went with him to Moscow and then St Petersberg, where he was admitted with a scholarship to become a science teacher.

As a teacher and chemist, he became well known throughout Russia and, despite being politically outspoken, he was tolerated by the Tsar and the authorities.

His lasting achievement was the creation of the Periodic Table of elements. Before this, the only real knowledge about elements was their atomic mass. By grouping the 62 known elements according to their properties (in increasing atomic mass), Mendeleev was able to predict the existence of unknown elements.

His table established the idea that there was some underlying order within atoms that produced the regularity in the properties. This would lead atomic and nuclear physicists to try to understand what caused this.

Mendeleev built his table around the idea of atoms from the earlier work of John Dalton J J Thomson and Rutherford relied on Mendeleev’s work to think about the structure of atoms . Bohr’s model of the atoms relied on Mendeleev’s ideas of periodicity .

1890 to 1920

The optimism of a new century spread into science. Many believed that all that was needed was to tidy up loose ends and refine measurements. This confidence was shattered by the discovery of radioactivity, the publication of Relativity and the First World War in Europe.

Hendrik Lorentz, physicist – He showed how fast objects contract (1853-1928)

Dutch born in Arnhem.

As well as being a great and influential theoretical physicist, Hendrick Lorentz was a modest man who was generous with his time and interested in other people.

Lorentz, like most 19th century physicists, was shocked by the discovery of radioactivity and had his confidence shaken by its implications for Physics. Yet, like Maxwell, whose work he developed, he contributed to the development of new strands of Physics – in his case, Special Relativity.

He developed theories of the production, propagation and reflection of light based on Maxwell’s equations and proposed the existence of electrons. He helped devise (and gave his name to) a set of mathematical transformations that calculate the contraction of a fast-moving object. Published in 1904, these form the basis of Einstein’s special theory of relativity.

In later life, he chaired the committee that analysed the expected movements of sea water when the Zuyderzee on the Dutch coast was drained and reclaimed from the sea.

Lorentz’s developed his transforms to work with * Hertz’s wave equation . Lorentz developed transforms to work with Maxwell’s equations . Einstein used Lorentz’s transforms in his Special Theory of Relativity .

Marie Curie née Maria Sklodowska, physicist – Lasting legacy from a tragic life (1867-1934)

French physicist born in Warsaw, Poland

Marie Curie was the first woman to win the Nobel Prize and the first person to win it twice. As well as her pioneering work in science, she was very active in the First World War, setting up mobile X-ray units with her daughter Eve Curie.

Marie Curie was working on magnetic effects. However, following Becquerel’s discovery of radiation, she switched her field of study. Given the strangeness of this new field, few men were studying it so it was easier for her, as a woman, to get backing.

She observed that the mineral pitchblende was more active than expected (given its uranium content). She concluded that there was a previously unknown chemical element in the pitchblende.

She worked tirelessly with her husband, Pierre, to chemically reduce the pitchblende and concentrate the unknown component. In the end, from tons of uranium ore, they obtained a few hundredths of a gram containing the source of the radiation. In it were two highly radioactive new chemical elements. They named them polonium, after Marie Curie’s homeland and radium.

When Pierre Curie was killed in a road accident, Marie Curie took over Pierre’s chair at the Sorbonne, becoming the first woman to teach there.

Because of a lack of knowledge about the dangers of radioactivity, she had been exposed to massive doses of radiation and she eventually died from leukemia.

Although this was a new branch of physics, Curie relied on the elements and gaps in Mendeleev’s table Rutherford used Curie’s discoveries to probe the atom

Sir Joseph John Thomson, physicist – Clumsy but accomplished experimenter (1856-1940)

Physicist born near Manchester, England.

Joseph John (J. J.) Thomson was going to be an engineer. However, after the death of his father (when Thomson was 16), his mother couldn’t afford the large apprenticeship fee. So he stayed at College in Manchester and, some years later, won a scholarship to Cambridge where he worked for the rest of his life.

At the age of 28, he was given the senior post at the Cavendish Laboratory despite, as his assistant put it “being very awkward with his fingers” and being discouraged from handling the instruments. He was, however, inspired with his designs for apparatus and interpretations of experimental results.

His work on gas discharges and cathode rays led, in 1897, to his discovery of the electron – his interpretation of the results of deflecting cathode rays.

A theorist as well as an experimenter, Thomson described the plum-pudding model of atomic structure, in which electrons were like negative ‘plums’ embedded in a ‘pudding’ of positive matter. This was the first step on the road to our current model of the atom.

Thomson’s discovery of the electron developed and helped explain Hallwachs’ experiment Thomson worked with Rutherford Einstein later explained the photoelectric effect using the electron Bohr developed Thomson’s model of the atom .

Max Planck, physicist – Almost a musician (1858-1947)

Physicist, born in Kiel, Germany

Max Planck was amongst the physicists who, at the end of the 19th century, felt there were a few loose ends to be tied up. He then became one of the founders of quantum physics in the 20th century. At school, he was as talented in music as he was in mathematics and considered taking up a career in music.

After advice from a musician – “if you need to ask advice, study something else” – he studied Physics and Mathematics at university. He went on to teach (at first for no salary) at a number of Universities before becoming professor of Theoretical Physics at Berlin University in 1888.

As a younger man, Planck had worked on thermodynamics – the classical physics of the late 19th century. In trying to solve the problem of the spectrum of black body radiation, he proposed that radiation was not given out in a continuous flow. He introduced the planck constant, h, to relate the energy to the frequency of radiation.

This theory revolutionised physics; Einstein used his ideas in his treatment of the photoelectric effect, saying that the radiation travels in discrete packets – or quanta – with an amount of energy E = hf. This was the beginning of quantum mechanics.

Planck built on Maxwell’s ideas of thermodynamics . Along with Michelson, Planck’s work led to a rethink on the behaviour of light . Einstein used Planck’s idea of packets of radiation to explain the photoelectric effect . Bohr’s model of the atom used quantised levels based on Planck’s ideas of packets of radiation .

Baron, Sir Ernest Rutherford, physicist – Why was he called “The Crocodile”? (1871-1937)

Physicist born in Nelson, New Zealand

Ernest Rutherford was born and grew up in rural New Zealand but worked in England and Canada. During his life, he founded nuclear physics, was the first successful alchemist and set up the Academic Assistance Council to help scientists flee Nazi Germany.

Rutherford left new Zealand at the age of 23, with three degrees and a scholarship to Cambridge, where he joined J. J. Thomson’s group at the Cavendish. He proposed that radioactivity was the spontaneous disintegration of atoms and conceived the idea of half life.

Working with Geiger, he showed that alpha particles were ionised helium and used them to probe inside gold atoms in his thin foil experiment. He was astonished by the results of this experiment saying it “was like firing an artillery shell at tissue paper and seeing it bounce back”. From this, he deduced that atoms must contain a dense nucleus.

He was a hugely popular and motivational team leader and was known as the ‘crocodile’ either because he wouldn’t let go of a problem or because he only ever looked forward or maybe because his booming voice signalled his approach like the ticking clock in Captain Hook’s favourite crocodile.

He went on to find proof of the proton, predict the neutron and transmute nitrogen into oxygen. He later achieved the alchemists’ goal of creating gold from another metal; unfortunately, the other metal was platinum, which is even more expensive than gold!

Rutherford used Marie Curie’s work on radioactivity to probe the atom. Rutherford and Thomson worked together . Geiger worked under Rutherford in Manchester and helped carry out the alpha scattering experiments. Bohr’s model of the atom developed Rutherford’s idea of a nucleus . Chadwick worked with Rutherford in Manchester and Cambridge .

Hans Geiger, nuclear physicist – A member of the “Uranium Club” (1882-1945)

Nuclear physicist born in Neustadt-an-der-Haardt.

Hans Geiger was born, educated and lived most of his life in Germany, spending 5 years at Manchester working with Ernest Rutherford.

He was a reluctant, conscript in the First World War and a member of the Uranium Club in the Second. He was a member of the Nazi party and was unsympathetic (at the least) to Jewish colleagues who lost their academic jobs after Hitler’s first race law in 1933. There is still debate whether the Uranium Club – the German Physicists charged with developing an atomic bomb – deliberately prevented Hitler getting the weapon.

Whilst with Rutherford in Manchester, he helped develop the techniques that led to the conception of a nucleus and, when he returned to Germany, developed the Geiger Mueller tube with Walther Mueller.

Geiger survived the Second World War but lost his home when it was occupied in 1945; he just lived to learn of the atomic bombs in Japan

Geiger was a student with Rutherford before the Second World War . Geiger’s work helped lead towards Bohr’s model of the atom; but they were very much on opposite sides in the War .

Albert Einstein, theoretical physicist – A great man who never wore socks (1879-1955)

Theoretical physicist born in Ulm, Germany.

Albert Einstein is, perhaps, the most famous physicist of all time. And his equation, E=mc2, the best known equation. He was a citizen of three countries, was married twice, never wore socks and didn’t talk until he was six.

In 1896, whilst living in Switzerland, Einstein renounced his German citizenship to avoid national service. He trained as a teacher but got a job in a patent office in 1902. He said this suited his desire to pursue Physics without the constrictions of an academic career.

In 1905, he published three papers that shook the world of Physics. The first explained Brownian motion and was the first direct evidence of molecules in motion; the second discussed the quantum nature of light and explained the photoelectric effect (based on Planck’s theory); the third introduced the Special Theory of Relativity. This gave a physical basis and interpretation to the Lorentz transformations and led to new and astonishing predictions.

He said that he started to get the ideas of Special Relativity when, at the age of 16, he imagined what it would be like to ride on a photon.

Einstein soon took up academic posts in Zurich, Prague, Berlin and (in 1933) Princeton where he remained (renouncing his German citizenship for a second time). In 1915, he published his General Theory of Relativity which tackled some of the problems of the Special Theory and included gravity. Its ideas about curved space and time were verified during a solar eclipse in 1919, turning Einstein into a world celebrity.

His last effort, a Unified Field Theory, which attempted to account for electromagnetic force and gravitational force using one set of laws was not entirely successful.

In 1939, prompted by other physicists, Einstein wrote a letter to President Roosevelt about the likelihood that the German government was making an atomic bomb. The letter helped lend urgency to efforts in the United States to build its own bomb but Einstein himself played no role in the work and knew nothing about it at the time.

Einstein brought about the biggest shift in ideas since Isaac Newton 250 years earlier Einstein’s theories of Relativity didn’t rely on an ether – thanks to Michelson’s experiment His theories showed how Maxwell’s equations could work in all situations One of Einstein’s 1905 papers explained the photoelectric effect – discovered by Hallwachs Einstein included the Lorentz transformations in his Special Theory of Relativity . Einstein based his explanation of the photoelectric effect on Planck’s idea of packets of radiation . Thomson’s work on the electron helped to explain the photoelectric effect . Einstein thought it unnecessary, Eddington led an expedition in 1919 that confirmed the predictions of General

Relativity Einstein supported Bose’s theory and added his name to the statistics of bosons . Bohr picked up on the idea of packets of radiation and developed it into the beginnings of quantum mechanics .

Niels Bohr, physicist – Why did he have to flee from Denmark? (1885-1962)

Physicist born in Copenhagen

Niels Bohr was one of the founders of quantum mechanics. He worked on an atomic model and on the atomic bomb and, in 1942, escaped from Nazi occupied Denmark with his son.

As an undergraduate, he studied nuclear physics under J. J. Thomson at Cambridge before moving to Manchester to work with Ernest Rutherford. Bohr’s work drew on Rutherford’s nuclear model of the atom and made use of Planck’s quantum theory. It suggested that the electrons in an atom exist in shells around the nucleus. This model contributed enormously to future developments of theoretical atomic physics and chemistry.

During the Second World War, he had a secret meeting with the German Physicist Heisenberg. The meeting is the subject of some fascinating speculation because the men were friends but on opposing sides (Denmark was occupied by the Germans). And America and Germany were both trying to develop nuclear weapons.

Bohr escaped from Denmark and made his way to America where he and his son joined in the effort at Los Alamos to develop the first atomic bomb. He opposed the complete secrecy of the project and after 1945 worked to develop peaceful uses for atomic energy.

Bohr developed a more complicated and successful model of the atom than Thomson’s . Bohr used Rutherford’s idea of an atomic nucleus to develop his model of the atom . Bohr included Planck’s theory on packets of radiation in his model of the atom . Heisenberg worked closely with Bohr and helped develop the new theory of quantum mechanics .

Edwin Hubble, astronomer – A lawyer or a liar? (1889-1953)

Astronomer born in Marshfield, Missouri.

Edwin Hubble, the privileged and talented son of an insurance manager, is now best known for the space telescope that carries his name.

Hubble was a handsome athlete, a gifted scholar and a story-teller – some would say a liar. Having had a charmed school career, he went to University in Chicago and Oxford (to study Law – his father objected to him being an astronomer).

When he returned to America, he spent some time as a school teacher (though he said he had been a lawyer) before, at the age of 25, he went back to astronomy.

He was an extremely gifted observer and showed that nebulae were in fact large star systems, or galaxies, several hundred light years outside the Milky Way.

In 1929, he observed that these galaxies were moving away from us and that their speed increased with their distance. This substantiated the theory of an expanding Universe and was one way of resolving Olber’s paradox. Much later, it led to the theory of the Big Bang.

Hubble’s observations and suggestion of receding galaxies helped explain Olber’s paradox . Arthur Eddington was the next famous astronomer . Gamow used Hubble’s results to develop the idea of The Big Bang .

Werner Heisenberg, physicist – Did he work on the bomb? It’s uncertain! (1901-1976)

Physicist born in Wurzburg.

Werner Heisenberg grew up with the First World War as his backdrop. One of the effects was to disrupt his formal education. However, he studied freely and became an accomplished mathematician, physicist and pianist.

At University in Munich, he was exposed to some of the problems of describing the structure of atoms. Whilst recovering from a bout of hay fever on a volcanic atoll, he is said to have come up with a novel (to him) method of multiplying variables. It turned out that he had developed matrices (though he had never seen a matrix before). This method of matrix mechanics is one way of solving problems in quantum mechanics.

From 1924 to 1927 he worked with the Danish physicist Niels Bohr and, in 1926, he came up with his famous principle of uncertainty. This states that, for a microscopic particle like an electron, it is impossible to precisely determine both its position and momentum at the same time. The act of measuring one of them makes the other one uncertain.

This principle has important philosophical and physical consequences because it means the difference between a Universe that is certain and predictable and one that is based on probability. It is one way of seeing that a clockwork Universe can never have a known starting position.

During the war, he had a secret meeting with Neils Bohr in occupied Denmark. There is much speculation and debate about this meeting and about Heisenberg’s involvement in the German atomic bomb project.

Heisenberg took Planck’s idea of packets of radiation and included it in the new field of quantum mechanics Heisenberg worked closely with Bohr on his theories Heisenberg wasn’t close to Schrödinger, who developed an alternative formulation of quantum mechanics

Erwin Schrödinger, physicist – What does his cat have to do with physics? (1887-1961)

Austrian physicist

Erwin Schrödinger was an accomplished physicist by the time he turned his mind to quantum mechanics. He had a particular interest and skill with waves and wave equations. Spurred on by the limited power of the Bohr model of the atom and de Broglie’s matter waves, Schrödinger took a holiday in the Alps to contemplate the hydrogen atom. (The story goes that he took his mistress, not his wife, for company).

What he developed was his wave equation and the beginnings of wave mechanics. The equation describes the probability of where we would find an electron in a given system such as a hydrogen atom.

The interpretation of the equation is key to our attempt to understand quantum mechanics. It predicts possible states and positions for particles. Not where they are but where they might be if you were to observe them.

He illustrates his ideas about probability in a famous thought experiment in which a hypothetical cat is put in a box with a devious device that links the microscopic world of probabilities to the life of the poor cat.

Schrödinger fled to Dublin during the Second World War because he strongly opposed the persecution of Jews. He became very disillusioned with the bomb project and wrote What is life? which prompted a number of Physicist to turn to molecular biology and hastened the discovery of DNA.

Schrödinger built on Planck’s idea of packets of radiation and included them in his wave equation . Schrödinger developed some of Bohr’s ideas on waves to create a version of quantum mechanics . Schrödinger wasn’t close to Heisenberg but between them they created quantum mechanics . Dirac developed a relativistic version of Schrödinger’s wave equation . Murray Gell-Mann took forward many of Schrödinger’s ideas of quantum mechanics into his theories of particles .

Paul Dirac, physicist – Where can you find his equation? (1902-1984)

Theoretical physicist born in Bristol, England.

Paul Dirac, like Newton and Rutherford before him, is buried in Westminster Abbey. However, he has the distinction of being under the only tombstone with an equation on it – the Dirac equation – a relativistic quantum equation for the electron.

His equation predicted the existence of the positron, or anti-electron – a particle with the same mass as an electron but opposite charge (and some other opposites).

Dirac’s theory was confirmed in 1932 when the American physicist Carl Anderson discovered the positron. In 1933 Dirac shared the Nobel Prize for Physics with the Austrian physicist Erwin Schrödinger.

In 1950, Dirac proposed string theory, a version of atomic theory which replaces the idea of elementary particles as points with the idea that they are loops or vibrating strands of energy.

Dirac developed a relativistic version of Schrödinger’s wave equation Dirac used Einstein’s relativity in his wave equation . Murray Gell-Mann took forward many of Dirac’s ideas on quantum mechanics into his theories of particles . Yukawa developed Dirac’s ideas in quantum mechanics in the 1930s .

Enrico Fermi, physicist – Where did he go after getting his Nobel prize? (1901-1954)

Italian/American physicist, born in Rome.

Enrico Fermi, the man who remarked “If I could remember the names of all these particles, I’d be a botanist” was a particle physicist. When he started out, there were very few particles: electrons, protons and neutrons; later the number of particles and their names became harder to handle!

Fermi was born and educated in Italy, which he left for America in 1938 (he fled to Chicago from Sweden where he had just received the Nobel Prize). This was partly because his wife had Jewish descent and partly because he was more likely to get funding there. Italy was a poor country as well as a Fascist one at the time.

Fermi was an expert on particle behaviour and on neutrons. When fission was discovered in 1939, he realised that the spare neutrons could be used to start a chain reaction.

In 1942, in a squash court at the University of Chicago, his team created the first nuclear fission chain reaction. For the rest of World War II he worked at the Los Alamos Scientific Laboratory on the atomic bomb project.

He later opposed the development of the hydrogen bomb on ethical grounds.

Fermi’s work relied on – and proved – Einstein’s most famous equation . Fermi used Rutherford’s theories of the nucleus . Fermi relied on Chadwick’s neutrons to create chain reactions . Fermi developed Marie Curie’s work on radioactivity and contributed to understanding it better .

Sir James Chadwick, physicist – A shy man, accidental physicist and internee of The Third Reich (1891-1974)

Physicist, born in Manchester, England.

James Chadwick was well known for his modesty and shyness and, the story goes, became a Physicist because of it. He applied to do Mathematics at Manchester, was interviewed for Physics by mistake and was too self conscious to mention it.

In 1909 he began working with Ernest Rutherford and teamed up with him again 9 years later in Cambridge. Between times, he spent four years interned in Germany where he had gone to work with Geiger and failed to leave before World War II broke out.

After the war years in prison, Chadwick returned to England and worked at the Cavendish with Rutherford. After ten years of experiments, he managed to find (or prove the existence of) the neutron in 1932. This led directly to the possibility of nuclear fission and, in 1943, Chadwick joined Fermi’s team at Los Alamos to work on the atomic bomb

Chadwick worked with Rutherford . Chadwick’s discovery of the neutron helped Fermi during the war . Gell-Mann later described the structure of neutrons and protons in terms of quarks .

Arthur Eddington, astrophysicist – How did he escape prison? (1882 – 1944 )

Astrophysicist born in Kendal, Cumbria.

Through his article, Report on the relativity theory of gravitation, Arthur Eddington introduced General Relativity to the English speaking world – the First World War had meant that this theory, published in German in 1915, was not well known.

Eddington also claimed he confirmed the predictions of General Relativity during the solar eclipse of 1919, turning Einstein into a world figure – even superstar! However, there is a bit more to this story.

Eddington was a conscientious objector during the First World War. This meant he should have been imprisoned. However, in 1918 the Astronomer Royal, for whom he worked, spoke up for him. He suggested that Eddington should prepare an expedition to an island off the African coast to measure the apparent shift in the position of stars as they were viewed from behind the Sun (a measurement that can only be made during an eclipse).

Einstein felt the trip was unnecessary but, by now, Eddington had too much invested in it to call it off – or to fail. Despite the fact that it rained throughout the eclipse, Eddington managed to get one photograph from which he claimed to prove General Relativity.

He is also known for his jocular (and immodest) response to a reporter who asked if it was true that only three people understood General Relativity. His answer: “I am trying to think who the third person is.”

Against Einstein’s wishes, Eddington led an expedition to try to verify General Relativity .

George Gamow, physicist – Third in the Greek alphabet (1904-1968)

Theoretical physicist born in Odessa, Ukraine.

George Gamow (‘Geo’ to his friends) was an accomplished physicist, author, science populariser and eccentric. He is best known for his description of the Hot Big Bang.

He was born in Russia and gradually made his way westwards through European Universities and defected to America in 1933.

In the 1920s, he developed quantum explanations of radioactivity and showed how low energy alpha particles could escape from the nucleus through quantum tunnelling. This prompted research that led to particle accelerators and chain reactions.

In the 1940s, he wrote a paper with his student Ralph Alpher which included a description of the Hot Big Bang. Hearing that the young Hans Bethe was in town, he invited him (on a whim) to add his name to the paper, which became the Alpher-Bethe-Gamow (alpha, beta, gamma) paper.

He predicted that the Big Bang would leave behind cosmic background radiation in the form of microwaves. This radiation was identified by Arno Penzias and Robert Wilson in 1965.

Gamow used Hubble’s results in his theory of the Big Bang Hoyle invented the term Big Bang to deride Gamow’s theory; Hawking further developed the theory . Starobinsky refined some of Gamow’s ideas of the early Universe .

Satyendra Nath Bose, physicist – Made his discovery from a mistake (1894-1974)

Satyendra Nath Bose

Physicist born in Calcutta, India

Satyendra Bose was the son of a railway engineer and a highly successful student. He was lecturing by the time he was 22 and, later, translated The General Theory of Relativity from German to English. He worked at Calcutta and Dacca, and studied X-ray diffraction.

During a lecture on the photoelectric effect (in which he was trying to show that theory did not predict the experimental results), he made a simple statistical error that did lead to the measured results. He used this accident to devise a different statistical approach to dealing with photons. His papers on the subject were rejected until he enlisted Einstein’s support.

So, in 1924, Satyendra Bose did publish his paper on black-body radiation which founded Bose-Einstein statistics; these treat photons as being indistinguishable from each other. The class of particles that behave in the same way are called bosons after him.

Bose convinced Einstein of the validity of his statistics and they cowrote a paper on them . Bose developed a set of statistics that work in situations where Maxwell’s does not work . Hoyle and Hawking relied on Bose’s translation of Einstein’s General Relativity .

1922 to 2000

The Physics revolutions of the beginning of the century laid the foundations for the age of information and communication technology. However, even now, the two big theories of Quantum Mechanics (for the very small) and Relativity (for the enormous) remain unreconciled. Physics is still moving on.

Hideki Yukawa, physicist – Forces and particles (1907-1981)

Physicist born in Tokyo

Hideki Yukawa did extensive research in quantum mechanics. In 1935, together with Ernest Stueckelberg, he predicted the existence of an elementary particle – the meson – with a mass about 200 times that of the electron, now called the pion.

The existence of the pion was proved in 1947.

Like Chadwick, Yukawa found a new particle. Yukawa took forward ideas on particle physics that were then developed by Gell-Mann

Salam developed Yukawa’s ideas in his theories on forces.

Sir Fred Hoyle, cosmologist – Gave us the ‘Big Bang’ – a theory he reviled (1915- 2001)

Astrophysicist and cosmologist, born at Bingley, in Yorkshire.

Fred Hoyle was born in Yorkshire and took an early interest in stars to which he returned having studied mathematics for his degree.

He was absolutely opposed to the idea that the Universe had a beginning – “Every cluster of galaxies, every star, every atom had a beginning, but the universe itself did not”. He argued for the steady state model and coined the term Big Bang to deride the opposition.

Hoyle interpreted Hubble’s results as a steady state Universe. Hoyle coined the term Big Bang to deride Gamow’s theory. Hawking was influenced by Hoyle but didn’t agree with the steady state Universe.

Edward Lorenz, meteorologist – Butterfly effect and chaos (1917 -)

Research meteorologist, MIT, Chicago

Edward Lorenz discovered the branch of mathematics known as Chaos. This deals with non-linear, sensitive systems that appear to be random but are driven by simple rules.

He was working on weather prediction during the 1960s using a basic computer to simulate weather patterns. He wanted to rerun some data and re-entered some values but to 3 significant figures instead of the 5 previously used. Although this was a tiny difference, to his surprise, the weather that the computer predicted was completely different.

He had discovered the Butterfly Effect – a classic example of chaos, where small changes in initial conditions produce large changes in the long-term outcome.

Mandelbrot’s fractal geometry links with Lorenz’s ideas on non-linear systems.

Benoit Mandelbrot, mathematician – A new geometry – fractals (1924- )

French/American mathematician born in Warsaw, Poland.

Benoit Mandelbrot developed fractal geometry as a method of dealing with the many complicated shapes and forms that exist in nature.

Fractals are geometric shapes that are very complex and infinitely detailed. You can zoom in on a section and it will have just as much detail as the whole fractal. His book The Fractal Geometry of Nature contains many examples of natural fractals such as ferns, trees, mountains and river basins.

He showed that fractals could be used as models of many natural phenomena, including the shape of coastlines, clouds, the clustering of galaxies and even stock market prices. Far from being unnatural, Mandelbrot held the view that fractals were, in many ways, more intuitive and natural than the artificially smooth objects of traditional Euclidean geometry.

His ideas sparked widespread popular interest in fractals as well as contributing to new fields of science such as the study of chaos.

Lorenz and Mandelbrot started the investigations into chaotic systems.

Stephen Hawking, physicist – Star of The Simpsons (twice) (1942- )

Theoretical physicist and cosmologist born in Oxford, England.

Stephen Hawking is probably the best known living Physicist – partly through his book A Brief History of Time and partly through his cartoon appearance on The Simpsons.

Hawking’s main Physics work has been to the theory of black holes and to the Big Bang Theory.

His first important paper was written with Roger Penrose in the mid 1960s. It predicted that the expanding Universe must have been born from a singularity – a mathematical point of zero volume where the laws of Physics cease.

At the time of the Big Bang, the singularity would have exploded and the Universe would have come into being. Space, time, and energy would have been created and would have expanded together.

In 1988 he published the best-seller “A brief history of time”, an introduction to quantum physics and relativity.

He has motor neurone disease and his physical condition has deteriorated so much that he is confined to a wheelchair and can communicate only by using one finger to move the cursor on the screen of a computer linked to a voice synthesizer.

Hoyle was an influence though Hawking doesn’t accept his ideas. Penrose and Hawking worked together on Black Holes. Starabinsky worked on inflationary theory. Guth worked on inflationary theory. Hawking has put Einstein’s General Theory of Relativity into modern cosmology.

Sir Roger Penrose, mathematical physicist – Geometry, Black Holes and consciousness (1931- )

Mathematical physicist, born in Colchester, Essex, England

Roger Penrose is known for his research in geometry, relativity, quantum mechanics and the theory of consciousness.

In 1965, Penrose showed that very massive stars could collapse in on themselves, and form objects called black holes.

At the centre of a black hole, there would be an object with an infinite density and zero size, called a singularity – a mathematical point of zero volume where the laws of Physics cease. As bizarre as they sound, singularities are not disallowed by the General Theory of Relativity.

Penrose has criticized the notion that human thinking is basically the same as the action of a very complicated computer.

His ideas on consciousness, put forward in his books The Emperor’s New Mind and Shadows of the Mind are controversial and have attracted some hostile criticism.

Penrose worked with Hawking on Black Holes Starabinsky worked on inflationary theory. Guth worked on inflationary theory. Penrose has put Einstein’s General Theory of Relativity into modern cosmology.

Murray Gell-Mann, American physicist – The ‘man with five brains’ (1929- )

Physicist, born in New York.

Murray Gell-Mann, or the ‘man with five brains’, as he has been called, has given us the eightfold way, the word quark and some confusion over its origin.

Gell-Mann was born in New York at the start of the Great depression. His father was an Austrian immigrant and strongly influenced the young Murray, who was teaching himself calculus when he was seven. He went to Yale at 15 and, as a compromise with his father, took Physics.

When he was 20 and now at MIT, he solved a problem of particle decay by introducing a new quantity called strangeness. From this he developed the eightfold way as a means of classifying subatomic particles and predicted the existence of the omega-minus – which was duly found.

To explain the plethora of new particles that were being discovered, Gell-Mann proposed a family of fundamental particles that he called ‘quarks’ (to rhyme with ‘walks’). He did not, as some suggest, lift the word from Finnegan’s Wake (in which it rhymes with ‘park’).

He has wide ranging interests (hence the “five brains” tag) including the connection between simplicity and complexity, the subjects of his popular book The Quark and the Jaguar.

Gell-Mann described the structure of Chadwick’s neutron. Gell-Mann explained the families of particles. Gell-Mann worked with Bardeen on QCD.

John Bardeen, physicist – Who came up with the name ‘gluon’?! (1908 to 1991)

Physicist born in Madison, Wisconsin

John Bardeen is the only person to have won two Nobel prizes in Physics.

In 1947, Bardeen, Shockley, and Brattain, working in Bell Labs on long distance telephone communication, invented the transistor. They were awarded the Nobel Prize for the invention in 1956. Without transistors, there would have been no computers, portable radios or televisions.

In 1972, Bardeen was awarded his second Nobel Prize, together with Leon Cooper and John Schrieffer for their theory of superconductivity, now called BCS theory.

With Gell-Mann and Fritsch, Bardeen developed Quantum Chromodynamics in 1972. This is a theory describing (in terms of gluons) the strong nuclear force between quarks.

Bardeen developed Yukawa’s ideas and discoveries in QCD. Bardeen worked with Gell-Mann on QCD.

Abdus Salam, physicist – Started a nuclear weapons programme (1926-1996)

Physicist, born in Jhang Sadar Pakistan

Abdus Salam achieved the first unification of forces since Maxwell brought together electricity and magnetism in the 19th century.

In Salam’s case, it was the electromagnetic and the weak forces that he unified into the electroweak force. Steven Weinberg independently proposed a similar theory at the same time and they shared the 1979 Nobel Prize along with Sheldon Glashow.

The theory has been a success in that it predicted the existence of W and Z bosons which have since been found at CERN.

In the early 1970s, Salam played a role in starting Pakistan’s nuclear weapons program.

Salam took forward ideas on particles and forces. Salam’s work is in the same field as Gell-Mann’s.

Alexei Starobinsky, physicist – Inflationary theory from behind the Iron Curtain (1950 – )

Theoretical physicist from The Landau Institute, Moscow

Starobinsky developed the first inflationary model of the Universe at the end of the 1970s – but it was not then called ‘inflation’. This model describes the rapid expansion of the Universe (from the size of a proton to the size of a grapefruit) almost immediately after it was created in the Big Bang.

It was a very complicated model based on a quantum theory of gravity, but it caused a sensation among cosmologists in what was then the Soviet Union, becoming known as the ‘Starobinsky model’.

Unfortunately, because of the difficulties Soviet scientists still had in travelling abroad or communicating with colleagues outside, the news did not spread outside their country.

Starobinsky’s work on inflationary theory develops some of Hawking’s ideas. Starobinsky developed ideas in Gamow’s Big Bang theory. Guth independently developed a similar theory.

Alan Guth, American physicist and cosmologist – Inflationary theory (1947 -)

Physicist and cosmologist from MIT, Chicago

Guth researched elementary particle theory (and how particle theory is applicable to the early universe).

In 1980 Guth, not knowing anything of Starobinsky’s work, proposed a different version of the Inflationary Theory based on the work of physicists such as Stephen Hawking. Inflation describes the rapid expansion of the Universe (from the size of a proton to the size of a grapefruit) almost immediately after it was created.

His theory explained how the Big Bang could produce a Universe that would eventually stop expanding and would also produce uniform microwave background radiation.

Guth’s work on inflationary theory develops some of Hawking’s ideas. Guth developed ideas in Gamow’s Big Bang theory. Starobinsky independently developed a similar theory.

Sir Tim Berners-Lee, physicist – Developed http and invented the World Wide Web (1955 -)

Physicist and computer scientist

Tim Berners-Lee was born in London in 1955. He studied Physics at Oxford, where he was banned from using the University’s computers after he hacked into the network. He is now best known for inventing the World Wide Web and for giving it to the world for free.

After graduating, Berners-Lee worked as a computer programmer and took a temporary job at CERN (see below) in the mid 1980s. He worked on an information system that used hypertext links to navigate between entries and show connections between them.

At that time, most Universities, research organisations and technology companies had their own computer networks; and there were links between these networks – the internet. Berners-Lee proposed a generalised method of sharing information between these networks over the internet.

Although his proposal wasn’t picked up, in 1990, he wrote the code that would allow networks to access and share hypertext documents over the internet – hypertext transfer protocol (http). He also wrote a programme to view these documents, a browser that he called WorldWideWeb and posted the world’s first web page.

He posted his programmes on internet newsgroups and they quickly became popular – particularly amongst scientists for sharing information over the internet. He did not patent the technology and was aware that big software companies might try to control what he felt should be an open and free system. In 1994, after a conference at CERN, the World Wide Web Consortium (W3C), headed by Berners-Lee, was set up to “lead the web to its full potential”.

CERN is the world’s biggest particle physics laboratory and houses particle accelerators that are among the largest scientific instruments ever built. In these devices, elementary particles are accelerated to tremendously high energies and then smashed together. These collisions, recorded by particle detectors, give a glimpse of matter as it was moments after the Big Bang. Work in the bubble chamber at CERN has provided evidence for the existence of quarks – first predicted by Gell-Mann in 1963.

The CERN laboratory uses the ideas and techniques started by Rutherford, Thomson and Chadwick CERN has confirmed many of the theories of the likes of Salam CERN has discovered particles predicted by the likes of Gell-Mann.