Heinrich Hertz: Discovered radio waves and photoelectric effect

                                         Heinrich Hertz

Lived 1857 – 1894.
In a series of brilliant experiments Heinrich Hertz discovered radio waves and established that James Clerk Maxwell’s theory of electromagnetism is correct. Hertz also discovered the photoelectric effect, so providing one of the first clues to the existence of the quantum world. The unit of frequency, the hertz, is named in his honor.

Beginnings
Heinrich Rudolf Hertz was born on February 22, 1857 in the German port city of Hamburg. He was the firstborn of five children.

His mother was Anna Elisabeth Pfefferkorn, the daughter of a physician.

His father was Gustav Ferdinand Hertz, an attorney who became a Senator.

His paternal grandfather, a wealthy Jewish businessman, had married into a Lutheran family and converted to Christianity.

Both of Heinrich’s parents were Lutherans, and he was raised in this faith. His parents, however, were more interested in his education than his religious advancement.

School
Aged six, Heinrich began at the Dr. Wichard Lange School in Hamburg. This was a private school for boys run by the famous educator Friedrich Wichard Lange. The school operated without religious influence; it used child-centered teaching methods, taking account of students’ individual differences. It was also strict; the students were expected to work hard and compete with one another to be top of the class. Heinrich enjoyed his time at school, and indeed was top of his class.

Unusually, Dr. Lange’s school did not teach Greek and Latin – the classics – needed for university entry. The very young Heinrich had told his parents he wanted to become an engineer. When they looked for a school for him, they decided that Dr. Lange’s alternative focus, which included the sciences, was the best option.

              Heinrich Hertz, aged about 12, with his father, mother, and two younger brothers.

Heinrich’s mother was especially passionate about his education. Realizing he had a natural talent for making things and for drawing, she arranged draftsmanship lessons for him on Sundays at a technical college. He started these aged 11.

Homeschool and Building Scientific Apparatus
Aged 15, Heinrich left Dr. Lange’s school to be educated at home. He had decided that perhaps he would like to go to university after all. Now he received tutoring in Greek and Latin to prepare him for the exams.

He excelled at languages, a gift he seems to have inherited from his father. A language specialist, Professor Redslob, who gave Heinrich some tuition in Arabic, advised his father that Heinrich should become a student of oriental languages. Never before had he met anyone with greater natural talent.

Heinrich also began studying the sciences and mathematics at home, again with the help of a private tutor.

He had a colossal appetite for hard work. His mother said:

When he sat with his books nothing could disturb him or draw him away from them.

Although he had left his normal school, he continued attending the technical college on Sunday mornings.

In the evenings he worked with his hands. He learned to operate a lathe. He built models, then began constructing increasingly sophisticated scientific apparatus, such as a spectroscope. He used this apparatus to do his own physics and chemistry experiments.

Architecture and the Army
Aged 17, Heinrich returned to school, the Johanneum, for a year in order to fully prepare for the classics exams that would admit him to university. Having passed the exams, he promptly changed his mind again, deciding to become an architect’s apprentice. He moved to Frankfurt, where by day he worked in an architect’s office, and in the evening he read physics books in German and Ancient Greek literature in the original Ancient Greek, naturally!

Architecture quickly bored him.
In spring 1876, aged 19, he moved again, to Dresden, to study engineering. After only a few months he was drafted into the army for a year’s compulsory service. Although he enjoyed the discipline of army life, he found the army boring. Rather miserably, he wrote home at one point:

“… day by day I grow more aware of how useless I remain in this world.”

HEINRICH HERTZ

1876

Becoming a Scientist
Physics in Munich
After completing his army service, the 20-year-old Hertz moved to Munich to begin an engineering course in October 1877. A month later, after much internal anguish, he dropped out of the course. He had decided that above all else he wanted to become a physicist.

He enrolled at the University of Munich, choosing courses in advanced mathematics and mechanics, experimental physics, and experimental chemistry.

After a successful year at Munich he moved to the University of Berlin because it had better physics laboratories than Munich.

Berlin, Helmholtz, and Recognition
In Berlin, aged 21, Hertz began working in the laboratories of the great physicist Hermann von Helmholtz.

Helmholtz must have recognized a rare talent in Hertz, immediately asking him to work on a problem whose solution he was particularly interested in. The problem was the subject of a fierce debate between Helmholtz and another physicist by the name of Wilhelm Weber.

The University of Berlin’s Philosophy Department, with Helmholtz’s encouragement, had offered a prize to anyone who could solve the problem: Does electricity move with inertia? Alternatively, we could frame the question in the form: Does electric current have mass? Or, as framed by Hertz: Does electric current have kinetic energy?

Hertz started work on the problem and quickly fell into a pleasant routine: attending a lecture each morning in either analytical dynamics or electricity & magnetism, carrying out experiments in the laboratory until 4pm, then reading, calculating, and thinking in the evening.

He personally designed experiments which he thought would answer Helmholtz’s question. He began to really enjoy himself, writing home:


The Prize
In August 1879, aged 22, Hertz won the prize – a gold medal. In a series of highly sensitive experiments he had demonstrated that if electric current has any mass at all, it must be incredibly small. We have to bear in mind that, when Hertz carried out this work, the electron – the carrier of electric current – had not even been discovered. J. J. Thomson’s discovery was made in 1897, 18 years after Hertz’s work.
Other physicists began to notice just how dazzling Hertz’s work had been – the young student had put together experiments at the forefront of physics, personally modifying apparatus as needed. His practical skills, developed at home in the evenings, were proving to be priceless. His prize-winning work was published in the prestigious journal Annalen der Physik.

Recognizing the incredible talent he had in his laboratory, Helmholtz now asked Hertz to compete for a prize offered by the Berlin Academy: verifying James Clerk Maxwell’s theory of electromagnetism. Maxwell had stated in 1864 that light was an electromagnetic wave and that other types of electromagnetic wave could exist.

Doctor of Physics
Hertz declined this project; he believed the attempt, with no guarantee of success, would take several years of work. He was ambitious and wanted to publish new results quickly to establish his reputation.

Instead of working for the prize, he carried out a masterful three-month project on electromagnetic induction. He wrote this up as a thesis. In February 1880, at the age of 23, his thesis brought him the award of a doctorate in physics. Helmholtz quickly appointed him as an assistant professor. Later that year Hertz wrote:

“I grow increasingly aware, and in more ways than expected, that I am at the center of my own field; and whether it be folly or wisdom, it is a very pleasant feeling.”


HEINRICH HERTZ
1880

Hertz stayed in Helmholtz’s laboratory until 1883, during which time he published 15 papers in academic journals.

Mathematical Physics at Kiel
Hertz was a gifted experimental physicist, but competition to secure a lectureship at Berlin was high.

Instead, with Helmholtz’s support, Hertz became a lecturer in mathematical physics at the University of Kiel. This position, theoretical rather than experimental, extended his abilities. At Kiel he began to get to grips with Maxwell’s equations, writing in his diary:

“Hard at Maxwellian electromagnetism in the evening. Nothing but electromagnetism.”



HEINRICH HERTZ
Diary, May 1884

The result of Hertz’s work was a highly regarded paper comparing Maxwell’s electromagnetic theory with competing theories. He concluded that Maxwell’s theory looked the most promising. In fact he reworked Maxwell’s equations into a more convenient form.

“From the start, Maxwell’s theory was the most elegant of all… the fundamental hypothesis of Maxwell’s theory contradicted the usual views, and was not supported by evidence from decisive experiments.”



HEINRICH HERTZ
Diary, May 1884

The Discovery of Radio Waves
If you would like a somewhat more detailed technical account of Hertz’s discovery, we have onehere.

Well-Equipped Laboratories and Attacking the Greatest Problem
In March 1885, desperate to return to experimental physics, Hertz moved to the University of Karlsruhe. Aged 28, he had secured a full professorship. He was actually offered two other full professorships, a sign of his flourishing reputation. He chose Karlsruhe because it had the best laboratory facilities.

Wondering about which direction his research should take, his thoughts drifted to the prize work Helmholtz had failed to persuade him to do six years earlier: proving Maxwell’s theory by experiment.

Hertz decided that this mighty undertaking would be the focus of his research at Karlsruhe.

A Spark that Changed Everything
After some months of experimental trials, the apparently unbreakable walls that had frustrated all attempts to prove Maxwell’s theory began crumbling.

It started with a spark.

It started with a chance observation early in October 1886, when Hertz was showing students electric sparks. Hertz began thinking deeply about sparks and their effects in electric circuits. He began a series of experiments, generating sparks in different ways.
He discovered something amazing. Sparks were producing a regular electrical vibration within the electric wires they jumped between. The vibration moved back and forth more often every second than anything Hertz had ever encountered before in his electrical work.

He knew the vibration was made up of rapidly accelerating and decelerating electric charges. If Maxwell’s theory were right, these charges would radiate electromagnetic waves which would pass through air just as light does.

Producing and Detecting Radio Waves
In November 1886 Hertz constructed the apparatus shown below.


The Oscillator. At the ends are two hollow zinc spheres of diameter 30 cm. The spheres are each connected to copper wire which runs into the middle where there is a gap for sparks to jump between.
He applied high voltage a.c. electricity across the central spark-gap, creating sparks.

The sparks caused violent pulses of electric current within the copper wires. These pulses reverberated within the wires, surging back and forth at a rate of roughly 100 million per second.

As Maxwell had predicted, the oscillating electric charges produced electromagnetic waves – radio waves – which spread out through the air around the wires. Some of the waves reached a loop of copper wire 1.5 meters away, producing surges of electric current within it. These surges caused sparks to jump across a spark-gap in the loop.

This was an experimental triumph. Hertz had produced and detected radio waves. He had passed electrical energy through the air from one device to another one located over a meter away. No connecting wires were needed.

Taking it Further
Over the next three years, in a series of brilliant experiments, Hertz fully verified Maxwell’s theory. He proved beyond doubt that his apparatus was producing electromagnetic waves, demonstrating that the energy radiating from his electrical oscillators could be reflected, refracted, produce interference patterns, and produce standing waves just like light.

Hertz’s experiment’s proved that radio waves and light waves were part of the same family, which today we call the electromagnetic spectrum.


The electromagnetic spectrum. Hertz discovered the radio part of the spectrum.

Strangely, though, Hertz did not appreciate the monumental practical importance of the electromagnetic waves he had produced.

“I do not think that the wireless waves I have discovered will have any practical application.”




HEINRICH HERTZ
         1890

This was because Hertz was one of the purest of pure scientists. He was interested only in designing experiments to entice Nature to reveal its mysteries to him. Once he had achieved this, he would move on, leaving any practical applications for others to exploit.

The waves Hertz first generated in November 1886 quickly changed the world.

By 1896 Guglielmo Marconi had applied for a patent for wireless communications. By 1901 he had transmitted a wireless signal across the Atlantic Ocean from Britain to Canada.

Hertz’s discovery was the foundation stone for much of our modern communications technology. Radio, television, satellite communications, and mobile phones all rely on it. Even microwave ovens use electromagnetic waves: the waves penetrate the food, heating it quickly from the inside.

Our ability to detect radio waves has also transformed the science of astronomy. Radio astronomy has allowed us to ‘see’ features we can’t see in the visible part of the spectrum. And because lightning emits radio waves, we can even listen to lightning storms on Jupiter and Saturn.

Scientists and non-scientists alike owe a lot to Heinrich Hertz.

The Photoelectric Effect
In 1887, as part of his work on electromagnetism, Hertz reported a phenomenon that had enormous implications for the future of physics and our fundamental understanding of the universe. It came to be known as the photoelectric effect.

He shone ultraviolet light on electrically charged metal, observing that the UV light seemed to cause the metal to lose its excess charge faster than otherwise.

He wrote the work up, published it in Annalen der Physik, and left it for others to pursue. It would have been a fascinating phenomenon for Hertz himself to investigate, but he was too wound up in his Maxwell project at the time.

Experimenters rushed to investigate the new phenomenon Hertz had announced.

In 1899 J. J. Thomson, the electron’s discoverer, established that ultraviolet light actually ejected electrons from metal.

This led Albert Einstein to rethink the theory of light. In 1905 he correctly proposed that light came in distinct packets of energy called photons. Photons of ultraviolet light have the right amount of energy to interact with electrons in metals, giving the electrons enough energy to escape from the metal.

Einstein’s explanation of the photoelectric effect was one of the key drivers in constructing an entirely new way of describing atomic-scale phenomena – quantum physics. Einstein was awarded the 1921 Nobel Prize in Physics for explaining effect Hertz had discovered 34 years earlier.

The photoelectric effect. Photons of UV light carry the correct amount of energy to eject electrons from a metal.

Some Personal Details and the End
In 1886, aged 29, Hertz married Elisabeth Doll in Karlsruhe. She was the daughter of a mathematician. They had two daughters, Johanna and Mathilde. Mathilde became an influential biologist, making thought-provoking discoveries in the field of how animals solve problems.

At the age of 35 Hertz became very ill, suffering severe migraines. Doctors thought he had an infection. They performed a series of operations, but Hertz continued to deteriorate.

Heinrich Rudolf Hertz died aged 36 in Bonn on January 1, 1894 of blood-vessel inflammation resulting from immune system problems – specifically granulomatosis with polyangiitis. He was buried in his hometown of Hamburg, in the Ohlsdorf Cemetery.

In 1930 the unit of frequency was named the hertz by the International Electrotechnical Commission. In 1960 the unit was made official by the General Conference on Weights and Measures.

Anaximander:An ancient scientific revolution

                                        Anaximander

2,600 years ago, Anaximander became the first person in recorded history to recognize that the earth exists as a solitary body which does not need to rest on top of anything else. Fascinated by the structure of the earth, he produced one of the first ever maps of the world. He did not restrict his thinking to astronomy and geography. He also theorized about evolution, concluding that life had first arisen in wet rather than dry conditions. He proposed that the first humans had been produced from fish.

Beginnings
Anaximander was born in approximately 610 BC in the Ancient Greek city of Miletus (now in Turkey). His father’s name was Praxiades. His mother’s name is not known.

None of Anaximander’s work survives. What we know of him was written by authors such as Aristotle in later times.

One of the most significant features of Anaximander’s early life is that he was born in the city of Miletus. Now largely forgotten, at the time of Anaximander’s birth the city was booming. It had grown into the greatest and wealthiest city in Ancient Greece.

About 14 years before Anaximander was born, Miletus had been the birthplace of the first scientist in recorded history, Thales. In fact, Anaximander was possibly a blood relative of Thales.

Thales the Teacher
Thales had traveled to Ancient Egypt, and possibly Babylon, where he had learned mathematics. After returning to Miletus, he had lifted mathematics to new, magnificent heights, inventing deductive proof and establishing pure mathematics as a separate discipline from applied mathematics.

Thales established the Milesian school. In doing so, he set in motion the triumphant journey of mathematics through the islands and cities of Ancient Greece – a journey that would peak three centuries later with the brilliant work of Archimedes.

The World’s First Science Student
Anaximander was one of Thales’ first students, perhaps the very first. Pythagoras was one of his later students. Pythagoras was also taught by Anaximander.

Thales’ core belief, which he passed to Anaximander, was that rational explanations rather than the Ancient Greek gods should be used to account for natural phenomena.

Anaximander’s ambition was startling. His overriding goal was to understand and explain the universe.

Anaximander – Cosmology and Science

Earth’s Place in the Universe
Anaximander had learned from Thales that the earth is a disk floating in an infinite ocean of water. Thales’ theory suggests that he had looked at the night sky and seen lots of bright disks. Describing the earth as a disk would therefore have seemed perfectly logical. Alternatively the disk idea might have come from the fact that the horizon, provided it’s unobstructed, is circular.

Anaximander modified Thales’ theory in a remarkably productive way. He completely discarded the ocean that Thales said supports the earth.

Earth Floats in the Center of the Infinite
Anaximander said there is nothing underneath the earth supporting it. He asserted that the earth floats in the center of infinity, held in position because it is an equal distance from all the other parts of the universe.

This is a strikingly sophisticated argument. More than 2,000 years before Newton’s law of gravity, Anaximander’s point of view seems to incorporate a subtle hint of Newtonian-style thinking.

Anaximander had made an immense conceptual leap. For the first time in history a human mind had grasped the idea that it is possible we live upon a mass that needs nothing below it.

It is difficult to overstate how important Anaximander’s revelation was for the future of astronomy and science. Without his insight, Aristarchus and (many years later) Nicolaus Copernicus could never have made the further intellectual leap needed to say that the earth orbits the sun.

“In my opinion this idea of Anaximander’s is one of the boldest, most revolutionary, and most portentous ideas in the whole history of human thought.”

KARL POPPER, 1902 – 1994

Philosopher of Science

 

How is the Universe Put Together?

Anaximander did not believe the universe he saw had always existed. He said it had grown from a seed – a primordial substance called Apeiron. The Apeiron was infinite and could not be created or destroyed. Everything we can sense in the universe had grown from it.

Tradition said that the sky was a solid hemisphere containing the heavenly bodies. It was supported above the earth by one of the Titans of Greek myths – Atlas.

Anaximander said that the heavenly bodies did not all lie on a single great celestial hemisphere. He placed the sun, the moon and the stars at different distances from Earth. However, after getting this right, he got the details wrong.

He imagined there were three rings of fire around earth – one for the sun, one for the moon, and one for the stars. The fires, he said, were enclosed in rings and hidden from us apart from holes that allowed their light through. The holes could change shape, which accounted for the moon’s phases. The holes could close, accounting for solar eclipses. The fire in the moon’s ring was cooler than the fire in the sun’s ring.

Although he correctly said the moon was closer to us that the sun, he incorrectly placed the stars closer to us than the moon.

Anaximander’s universe. The sun, moon, and stars are holes through which we can glimpse the fires within the three enclosed rings that surround the earth. Each ring of fire is the same width as the earth. The sun’s ring begins 27 earth-widths away from the earth.

To people today, Anaximander’s fire-rings look crazy. However, the fact that he imagined rings going all the way around Earth also allowed him to visualize an Earth that needed no support. So, despite the apparent craziness of his fire-rings idea, it led to a revolution in our understanding of the universe.

What Does the Earth Look Like?
Anaximander accepted Thales’ idea that the earth is a rather deep disk. We live on one side of the disk. We do not know what exists on the other side. He believed the depth of our disk-world was a third of its width.

Anaximander was clearly obsessed with visualizing the universe, how the earth related to the rest of the universe, and what the earth’s surface looked like. One result of this is that he created a map of the world, much more extensive than any known before it.

He compiled reports from anyone who had traveled outside Greece and tried to present the information in visual form. The map no longer exists, but from descriptions written by Heroditus, who lived a century after Anaximander, we may theorize that it looked something like the one below.



Other Worlds
Anaximander believed that the world we live on has not always existed and will not always exist. He believed worlds had existed before ours and others would exist after ours.

Lightning Storms and Rain
Thales had attempted to explain earthquakes as a natural phenomenon rather than the actions of angry gods.

Anaximander did the same for lightning storms, which he said are caused by disturbances in the air. Lightning results from violent air flow, while thunder results from the collisions of clouds.

Rain is produced by water that has risen from the earth by the heat of the sun. (Anaximander worried that one day all of earth’s water could be lost by this process.)

Evolution
Anaximander looked at the life around him and came to the conclusion that it must have evolved from other lifeforms. He believed the world’s first lifeforms originated in the world’s wetter environments, then evolved into more advanced forms and spread to drier places.

He believed humans could not have appeared on Earth in their current form. His reasoning was that the young of some animals can look after themselves from the time they are born. Human children, however, need to be taken care of for many years. If this had always been the case, humans could not have survived.

Anaximander speculated that our ancestor may have been a fish-like creature which gave birth to humans when they had reached an age when they could survive without parents to look after them.

                         Meet your ancestor – according to Anaximander

Barbara McClintock

                              Barbara McClintock

                                                            Lived 1902 – 1992.

Barbara McClintock made a number of groundbreaking discoveries in genetics. She demonstrated the phenomenon of chromosomal crossover, which increases genetic variation in species. She also discovered transposition – genes moving about within chromosomes – often described as jumping genes, and showed that genes are responsible for switching the physical traits of an organism on or off.

Beginnings

Barbara McClintock was born on June 16, 1902 in Hartford, Connecticut, USA. She was christened Eleanor McClintock, but her parents soon started calling her Barbara: they considered this name a perfect match for her forthright, no-nonsense character; they had come to believe that Eleanor was too feminine and gentle a name for their daughter.

Her father, Thomas Henry McClintock, was a family doctor whose parents had come to America from Britain. Her mother, Sara Handy, came from an upper-class Boston family; she was a housewife, poet and artist. Barbara was the third of the couple’s four children.

From the start, Barbara and her mother got on rather badly. Between the ages of three and five, to help reduce the stress on her mother, Barbara spent most of her time living with her aunt and uncle in Massachusetts.

Barbara returned to her parents in Hartford to begin school. In 1908 the whole family moved to Brooklyn, New York.

In contrast to her shaky relationship with her mother, Barbara always got on very well with her father. Both parents did everything they could to allow Barbara to grow into the person she wanted to be, even allowing her to skip school if she wished to do something else. From an early age, being the person she wanted to be meant being alone. Barbara preferred her own company to anyone else’s.

At Brooklyn’s Erasmus Hall High School her teachers could see that Barbara was exceptionally clever, and perhaps destined for life as a college professor. Her mother was very uncomfortable about this, believing that female college professors were bizarre creatures. Afraid that it would turn Barbara into an oddball nobody would ever want to marry, she refused to allow her daughter to go to college.

Starting College

Eventually, in September 1919, Barbara’s father overcame her mother’s objections and, aged 17, Barbara rushed off to enroll at Cornell University in Ithaca, New York. Leaving home was a liberating experience for Barbara. She grew happier, more relaxed, and enjoyed her time as an undergraduate. Her intense desire to be alone also faded: she socialized with other students, joined a jazz band, and was elected president of the women’s freshman class.

Dr. McClintock

Barbara McClintock took her first genetics course in 1921. Her ability in this field soon caught the attention of her teacher, Claude Hutchison, who recommended that she should jump straight on to the graduate-level course the following year. She was delighted to do this, all the time growing ever more fascinated by the genetics of plants. After receiving a B.S. in agriculture in 1923, she decided to pursue her fascination at graduate school.

                                                    Barbara McClintock and her father in about 1923, the year she got her B.S. degree. Image courtesy of BMC Collection Photographs, Cold Spring Harbor Laboratory.

 1925 McClintock was awarded an M.S. in botany and in 1927 a Ph.D. in botany, both earned at Cornell.

Her M.S. and Ph.D. degrees involved investigations of plant genetics. This would be the focus of her research for more or less the rest of her life.

After she completed her Ph.D., Cornell appointed McClintock to the role of instructor in the Botany Department.

Cytogenetics

McClintock worked in plant cytogenetics, meaning she used microscopes to investigate plant genetics at the cellular level – particularly studying chromosomes, the chunks of genetic code sitting inside cells. Cytogenetics had begun to reveal more of the secrets of life than traditional style genetics could.

Traditional style genetics involved breeding successive generations of an organism and observing differences visible to the naked eye. Gregor Mendel’s work on heredity exemplified the older style of genetics studies.

Cytogeneticists did everything a traditional geneticist would do, plus they also correlated their observations with changes taking place within cells.

Barbara McClintock’s Contributions to Science

Chromosomal Crossover

In addition to her own individual research work and her teaching load, McClintock began guiding Harriet B. Creighton, a graduate student. In 1931 the pair published a major discovery.

McClintock and Creighton had been researching the behavior of chromosomes

Cells carry their genetic code in structures called chromosomes, which contain DNA. (The role of DNA in chromosomes was unknown when McClintock & Creighton were doing their chromosomal crossover work.)

McClintock had developed improved staining techniques, which allowed her to see chromosomes under the microscope better than anyone else had before.

Using these staining techniques McClintock and Creighton proved the existence of chromosomal crossover.

Chromosomal crossover happens when the cells that take part in sexual reproduction are being made in a process called meiosis. In animals these are the egg and sperm cells.

Like many of the other cells in our bodies, sex cells contain chromosomes.

BUT… egg and sperm cells are different from normal cells because they only contain half the normal number of chromosomes. In the case of a human, a normal cell contains 46 chromosomes, while sex cells contain 23.

When egg and sperm cells merge during reproduction, they each provide 23 chromosomes to produce a new cell with 46 chromosomes. This new cell will grow into a new person. Half of its chromosomes come from mom and half from dad.

What McClintock & Creighton discovered is that when sex cells are being manufactured, nature can shuffle the genetic pack of cards to produce chromosome variations before sexual reproduction has happened.

Imagine a cell in dad’s body. This is a special cell that is going to produce sperm cells. This cell contains 46 chromosomes, 23 of which dad inherited from his dad (paternal chromosomes) and 23 from his mom (maternal chromosomes). Each paternal chromosome in the cell is paired with a maternal chromosome to form 23 chromosome pairs.

A chromosome contains a strand of DNA. This is one of the 23 chromosomes dad inherited from his dad.

Each paternal chromosome is paired with a maternal chromosome.

Each of the 23 chromosomes dad inherited from his dad is paired with one he inherited from his mom, making 23 pairs of chromosomes in a typical cell.

To make new cells, every chromosome makes a copy of itself so now there are two identical packages of DNA attached in a single chromosome, as shown.

This paternal chromosome now consists of two identical strands of genetic material linked together making an X shape.

This paternal chromosome continues to be paired off with its maternal partner as shown below.

McClintock & Creighton showed that these chromosomes line up and then crossover as shown below:

The chromosomes swap sections of genetic material (we now know that these are sections of DNA) to produce new chromosomes. In the image below you can see that the new chromosomes now have different genetic coding from the originals.

So genetic variations are being introduced even before the sperm cell meets an egg cell.

The two chromosomes shown above split in half to produce the genetic material for four sperm cells. Each of the four sperm cells will be genetically different.

Each human sperm cell contains 23 different chromosomes ready to pair with 23 chromosomes in an egg cell to make a genetically unique new living being.

Chromosomal crossover had been proposed as a theory 20 years earlier by Thomas Morgan to account for the way offspring inherit genes from their parents. McClintock & Creighton showed that the theory was correct. They did this by showing how the changes they saw in chromosomes during the production of maize sex cells exactly matched the changes in traits observed in maize plants grown from the fertilized seeds.

X-rays, Breaking, Fusion & Bridging, and the Centromere

In 1936, at the age of 34, McClintock became an assistant professor at the University of Missouri, where she worked until 1941.

A few years earlier, in the summers of 1931 and 1932, McClintock had visited Missouri and learned how to use X-rays to cause mutations in cells.

When she returned in 1936, she began using X-rays again. She discovered that large-scale mutations can arise from breaking, fusion and bridging of chromosomes. This BFB cycle, discovered by McClintock, leads to chromosomal instability, which means daughter cells have a different number of chromosomes from the cell that produced them. Although she discovered the phenomenon in the late 1930s, this is still an active research field today. Chromosomal instability is common in cancers.

In 1938 McClintock analyzed the cell genetics of the chromosome’s centromere, for the first time describing how it functions.

The centromere (the dull yellow circle in the image) links two identical strands of genetic material in the chromosome.

Her time at the University of Missouri was relatively unhappy. Although she could be rather abrasive and intimidating herself, at Missouri she came up against the even more abrasive and intimidating Mary Guthrie, another assistant professor, who also worked in cytology. McClintock and Guthrie got on exceptionally badly, making McClintock’s life miserable all too frequently. She also (incorrectly) saw no prospects of ever getting a secure, tenured position at Missouri. She decided it was time to move on.

The Final Professional Move

In early 1941, aged 38, McClintock became a visiting professor at Columbia University in New York.

In 1942 she accepted a temporary genetics position at the Cold Spring Harbor Laboratory on Long Island. Within a year she had been offered and accepted a permanent faculty position. She was very pleased with her new role. She no longer had teaching duties, and she had freedom to do whatever research she liked. She would work at Cold Spring Harbor for the rest of her career.

In 1944 she became the third woman ever to be elected to America’s National Academy of Sciences.

Mobile Genetic Elements & the Nobel Prize

Jumping Genes

Beginning in 1944 McClintock studied the relationship between color patterns on corn plants and the look of their chromosomes.

One of the colors she was most interested in was purple. She wanted to understand the genetic reasons for purple-spotted corn.

The corn plants from one generation to the next were self-pollinated. Comparing offspring with parent chromosomes, she found it looked like the offspring chromosomes were reorganized versions of parent chromosomes. Parts of the chromosomes looked like they had been snipped out and shifted to entirely new locations.

She had discovered parts of the chromosome – she called them Dissociators (Ds) and Activators (Ac) – which could cause insertions, deletions, and relocations of genes in the chromosome.

The theory of the time said genes were in fixed positions on the chromosome: McClintock’s work showed this was wrong.

The Dissociator could break the chromosome and alter the behavior of genes around it, but only in the presence of the Activator. The purple color could be switched on or off by the Dissociator. In other words, physical traits were being controlled by Dissociators and Activators.

In 1948 she discovered that Dissociators and Activators could transpose – in other words, jump to different places on the chromosome. They are often, therefore, called transposable elements.

Mobile/Controlling Elements

McClintock produced a theory that the Dissociators (Ds) and Activators (Ac) were in fact gene controllers – she called them controlling elements. They controlled the genes on a chromosome – they could inhibit or modify their behavior. This explained why an individual living thing, such as a person, can produce all sorts of different cells even though every cell has the same genetic code. The gene controllers make the difference by giving specific instructions in specific circumstances.

In McClintock’s view, genes could no longer be thought of as unchangeable instructions handed from parents to offspring. They could react to specific circumstances in the environment. Mobile genes could jump around within chromosomes and switch physical traits on or off.

She studied this phenomenon until 1950 before she began publishing her work.

In a scientific world that believed genes were very stable and could only change a little at a time, her findings were so radical that she was worried about how people would react to them.

You can see why I have not dared publish an account of this story. There is so much that is completely new and the implications are so suggestive of an altered concept of gene mutation that I have not wanted to make any statements until the evidence was conclusive enough to make me confident of the validity of the concepts… The size of the job ahead is staggering to contemplate, however.”

 

Her Machines Came From Too Far Away

McClintock presented her work in 1951 to an audience of key players from America’s universities at Cold Spring Harbor’s annual summer symposium. She focused on her theory of controlling elements as gene regulators. She was dismayed by the reaction. Other scientists could not follow her line of thought.

Although she had won plenty of recognition for her previous work, McClintock regarded her work on mobile genetic elements as her most important work by far, yet nobody seemed to be taking any notice of it. Feeling ignored, she became depressed. She stopped publishing her work in this field.

McClintock’s dismay has close parallels with Richard Feynman’s dismay three years earlier when he presented his revolutionary ideas in quantum field theory at the Pocono Conference in 1948. In the end, after getting nowhere with his presentation to America’s best physicists, he realized: “I had too much stuff. My machines came from too far away.”

In Feynman’s case, a young mathematical physicist by the name of Freeman Dyson came to his rescue. He translated Feynman’s work into terms other physicists could understand. Unfortunately, in cytogenetics, there was no Freeman Dyson to act as Barbara McClintock’s white knight.

Slowly Moving Forward

In 1960 Francois Jacob and Jacques Monod started to publish their work describing genetic regulation in bacteria. Realizing the similarities between their work and hers, McClintock responded in 1961 with a paper: Some Parallels Between Gene Control Systems in Maize and in Bacteria.

Slowly, her theory of transposable elements and gene control began to gain credibility.

At the beginning of the 1970s molecular biologists discovered transposition taking place in bacteria and viruses. They began to see that transposition was important in immunology and cancer. Scientists also saw the potential importance of transposition in manipulating genes to function in the way scientists wanted them to – genetic engineering.

Today we know that 50 percent of the human genome is made up of transposable elements!

Major Official Recognition

In May 1971 McClintock received the National Medal of Science from President Richard Nixon. A large number of other awards and honorary degrees followed, culminating in the 1983 Nobel Prize in Physiology or Medicine “for her discovery of mobile genetic elements.”

She was, by this time, 81 years old.

Some Personal Details and the End

Although she abandoned her life as a loner when she started college, McClintock never made close friends. She regarded herself as a free spirit; coming too close to anyone might have robbed her of some of that precious freedom. She enjoyed her privacy. She did not marry and had no children.

Barbara McClintock died aged 90 of natural causes in Huntington, New York, on September 2, 1992. She died peacefully. Her mind remained clear and intellectually vigorous to the end. She was buried in the Huntington Rural Cemetery.

Michael Faraday

                                              Michael Faraday

Michael Faraday, who came from a very poor family, became one of the greatest scientists in history. His achievement was remarkable in a time when science was the preserve of people born into privileged families. The unit of electrical capacitance is named the farad in his honor, with the symbol F.

Education and Early Life

Michael Faraday was born on September 22, 1791 in London, England, UK. He was the third child of James and Margaret Faraday. His father was a blacksmith who had poor health. Before marriage, his mother had been a servant. The family lived in a degree of poverty.

Michael Faraday attended a local school until he was 13, where he received a basic education. To earn money for the family he started working as a delivery boy for a bookshop. He worked hard and impressed his employer. After a year, he was promoted to become an apprentice bookbinder.

Bookbinding and Discovering Science

Michael Faraday was eager to learn more about the world; he did not restrict himself to binding the shop’s books. After working hard each day, he spent his free time reading the books he had bound.

Gradually, he found he was reading more and more about science. Two books in particular captivated him:

• The Encyclopedia Britannica – his source for electrical knowledge and much more
• Conversations on Chemistry – 600 pages of chemistry for ordinary people written by Jane Marcet

He became so fascinated that he started spending part of his meager pay on chemicals and apparatus to confirm the truth of what he was reading.

As he learned more about science, he heard that the well-known scientist John Tatum was going to give a series of public lectures on natural philosophy (physics). To attend the lectures the fee would be one shilling – too much for Michael Faraday. His older brother, a blacksmith, impressed by his brother’s growing devotion to science, gave him the shilling he needed.

It is worth saying that the parallels in the lives of Michael Faraday and Joseph Henry are rather striking. Both were born in poverty; had fathers who often could not work because of ill-health; became apprentices; were inspired to become scientists by reading particular books; were devoutly religious; became laboratory assistants; their greatest contributions were made in the same scientific era in the field of electrical science; and both have an SI unit named in their honor.

Introduction to Humphry Davy and More Science

Faraday’s education took another step upward when William Dance, a customer of the bookshop, asked if he would like tickets to hear Sir Humphry Davy lecturing at the Royal Institution.

Sir Humphry Davy was one of the most famous scientists in the world. Faraday jumped at the chance and attended four lectures about one of the newest problems in chemistry – defining acidity. He watched Davy perform experiments at the lectures.

This was the world he wanted to live in, he told himself. He took notes and then made so many additions to the notes that he produced a 300 page handwritten book, which he bound and sent to Davy as a tribute.

An 1802 drawing by James Gillray of another exciting science lecture at the Royal Institution! Humphry Davy is the dark-haired man holding the gas bag.

At this time Faraday had begun more sophisticated experiments at the back of the bookshop, building an electric battery using copper coins and zinc discs separated by moist, salty paper. He used his battery to decompose chemicals such as magnesium sulfate. This was the type of chemistry Humphry Davy had pioneered.

In October 1812 Faraday’s apprenticeship ended, and he began work as a bookbinder with a new employer, whom he found unpleasant.

Others’ Misfortunes Help Faraday

And then there was a fortunate (for Faraday) accident. Sir Humphry Davy was hurt in an explosion when an experiment went wrong: this temporarily affected his ability to write. Faraday managed to get work for a few days taking notes for Davy, who had been impressed by the book Faraday had sent him. There were some advantages to being a bookbinder after all!

When his short time as Davy’s note-taker ended, Faraday sent a note to Davy, asking if he might be employed as his assistant. Soon after this, one of Davy’s laboratory assistants was fired for misconduct, and Davy sent a message to Faraday asking him if he would like the job of chemical assistant.

Would he like the job? Working in the Royal Institution, with one of the most famous scientists in the world? There could only be one answer!

Michael Faraday’s Career at the Royal Institution

Faraday began work at the Royal Institution of Great Britain at the age of 21 on March 1, 1813.

His salary was good, and he was given a room in the Royal Institution’s attic to live in. He was very happy with the way things had turned out.

He was destined to be associated with the Royal Institution for 54 years, ending up as a Professor of Chemistry.

Faraday’s job as a chemical assistant was to prepare apparatus for the experiments and the lectures at the Royal Institution.

At first, this involved working with nitrogen trichloride, the explosive which had already injured Davy. Faraday himself was knocked unconscious briefly by another nitrogen chloride explosion, and then Davy was injured again, finally (thankfully) putting to an end to work with that particular substance.

After just seven months at the Royal Institution, Davy took Faraday as his secretary on a tour of Europe that lasted 18 months.

During this time Faraday met great scientists such as André-Marie Ampère in Paris and Alessandro Volta in Milan. In some ways, the tour acted like a university education, and Faraday learned a lot from it.

He was, however, unhappy for much of the tour, because in addition to his scientific and secretarial work, he was required to be a personal servant to Davy and Davy’s wife, which he did not enjoy. Davy’s wife refused to treat Faraday as an equal, because he had come from a lower class family.

Back in London, though, things began to look better again. The Royal Institution renewed Faraday’s contract and increased his salary. Davy even began to acknowledge him in academic papers:

“Indebted to Mr. Michael Faraday for much able assistance.”

In 1816, aged 24, Faraday gave his first ever lecture, on the properties of matter, to the City Philosophical Society. And he published his first ever academic paper, discussing his analysis of calcium hydroxide, in the Quarterly Journal of Science.

In 1821, aged 29, he was promoted to be Superintendent of House and Laboratory of the Royal Institution. He also married Sarah Barnard. He and his bride lived in rooms in the Royal Institution for most of the next 46 years: no longer in attic rooms; they now lived in a comfortable suite Humphry Davy himself had once lived in.

In 1824, aged 32, he was elected to the Royal Society. This was recognition that he had become a notable scientist in his own right.

In 1825, aged 33, he became Director of the Royal Institution’s Laboratory.

In 1833, aged 41, he became Fullerian Professor of Chemistry at the Royal Institution of Great Britain. He held this position for the rest of his life.

In 1848, aged 54, and again in 1858 he was offered the Presidency of the Royal Society, but he turned it down.

Michael Faraday’s Scientific Achievements and Discoveries

It would be easy fill a book with details of all of Faraday’s discoveries – in both chemistry and physics. It is not an accident that Albert Einstein used to keep photos of three scientists in his office: Isaac Newton, James Clerk Maxwell and Michael Faraday.

Funnily enough, although in Faraday’s lifetime people had started to use the word physicist, Faraday disliked the word and always described himself as a philosopher.

He was a man devoted to discovery through experimentation, and he was famous for never giving up on ideas which came from his scientific intuition.

If he thought an idea was a good one, he would keep experimenting through multiple failures until he got what he expected; or until he finally decided that mother nature had shown his intuition to be wrong – but in Faraday’s case, this was rare.

Discovery of Electromagnetic Rotation

This is a glimpse of what would eventually develop into the electric motor, based on Hans Christian Oersted’s discovery that a wire carrying electric current has magnetic properties.

Faraday’s electromagnetic rotation apparatus. Electricity flows through the wires. The liquid in the cups is mercury, a good conductor of electricity. In the cup on the right, the metal wire continuously rotates around the central magnet as long as electric current is flowing through the circuit.

Gas Liquefaction and Refrigeration

In 1802 John Dalton had stated his belief that all gases could be liquified by the use of low temperatures and/or high pressures. Faraday provided hard evidence for Dalton’s belief by applying pressure to liquefy chlorine gas and ammonia gas for the first time.

The ammonia liquefaction was of further interest, because Faraday observed that when he allowed the ammonia to evaporate again, it caused cooling.

The principle of cooling by artificial evaporation had been demonstrated publicly by William Cullen in Edinburgh in 1756. Cullen had used a pump to reduce the pressure above a flask of ether, causing the ether to evaporate quickly. The evaporation caused cooling, and ice formed on the outside of the flask as moisture from the air came into contact with it.

The importance of Faraday’s discovery was that he had shown that mechanical pumps could transform a gas at room temperature into a liquid. The liquid could then be evaporated, cooling its surroundings and the resulting gas could be collected and compressed by a pump into a liquid again, then the whole cycle could be repeated. This is the basis of how modern refrigerators and freezers work.

In 1862 Ferdinand Carré demonstrated the world’s first commercial ice-making machine at the Universal London Exhibition. The machine used ammonia as its coolant and produced ice at the rate of 200 kg per hour.

Discovery of Benzene

Historically, benzene is one of the most important substances in chemistry, both in a practical sense – i.e. making new materials; and in a theoretical sense – i.e. understanding chemical bonding. Michael Faraday discovered benzene in the oily residue left behind from producing gas for lighting in London.

Discovery of Electromagnetic Induction

This was an enormously important discovery for the future of both science and technology. Faraday discovered that a varying magnetic field causes electricity to flow in an electric circuit.

For example, moving a horseshoe magnet over a wire produces an electric current, because the movement of the magnet causes a varying magnetic field.

Previously, people had only been able to produce electric current with a battery. Now Faraday had shown that movement could be turned into electricity – or in more scientific language, kinetic energy could be converted to electrical energy.

Most of the power in our homes today is produced using this principle. Rotation (kinetic energy) is converted into electricity using electromagnetic induction. The rotation can be produced by high pressure steam from coal, gas, or nuclear energy turning turbines; or by hydroelectric plants; or by wind-turbines, for example.

Faraday’s Laws of Electrolysis

Faraday was one of the major players in the founding of the new science of electrochemistry. This is the science of understanding what happens at the interface of an electrode with an ionic substance. Electrochemistry is the science that has produced the Li ion batteries and metal hydride batteries capable of powering modern mobile technology. Faraday’s laws are vital to our understanding of electrode reactions.

 Invention of the Faraday Cage

Faraday discovered that when an electrical conductor becomes charged, all of the extra charge sits on the outside of the conductor. This means that the extra charge does not appear on the inside of a room or cage made of metal.

The image at the top of this page has a man wearing a Faraday Suit – which has a metallic lining – keeping him safe from the electricity outside his suit.

In addition to offering protection for people, sensitive electrical or electrochemical experiments can be placed inside a Faraday Cage to prevent interference from external electrical activity.

Faraday cages can also create dead zones for mobile communications.

Discovery of the Faraday Effect – a magneto-optical effect

This was another vital experiment in the history of science, the first to link electromagnetism and light – a link finally described fully by James Clerk Maxwell’s equations in 1864, which established that light is an electromagnetic wave.

Faraday discovered that a magnetic field causes the plane of light polarization to rotate.

… when the contrary magnetic poles were on the same side, there was an effect produced on the polarized ray, and thus magnetic force and light were proved to have relation to each other…

 Discovery of Diamagnetism as a Property of all Matter

Most people are familiar with ferromagnetism – the type shown by normal magnets.

The frog is slightly diamagnetic. The diamagnetism opposes a magnetic field – in this case a very strong magnetic field – and the frog floats because of magnetic repulsion. Image by Lijnis Nelemans, High Field Magnet Laboratory, Radboud University Nijmegen.

Faraday discovered that all substances are diamagnetic – most are weakly so – some are strongly so.

Diamagnetism opposes the direction of an applied magnetic field.

For example, if you held the north pole of a magnet near a strongly diamagnetic substance, this substance would be pushed away by the magnet.

Diamagnetism in materials, induced by very strong modern magnets, can be used to produce levitation. Even living things, such as frogs, are diamagnetic – and can be levitated in a strong magnetic field.

The End

Michael Faraday died in London, aged 75, on August 25, 1867. He was survived by his wife Sarah. They had no children. He had been a devout Christian all of his life, belonging to a small branch of the religion called Sandemanians.

During his life, he had been offered burial in Westminster Abbey along with Britain’s kings and queens and scientists of the stature of Isaac Newton. He turned this down, in favor of a more modest end. His grave, where Sarah is also buried, can still be seen in London’s Highgate Cemetery.

Srinivasa Aiyangar Ramanujan

Srinivasa Aiyangar Ramanujan

Born: 22 December 1887 in Erode, Tamil Nadu state, IndiaDied: 26 April 1920 in Kumbakonam, Tamil Nadu state, India

Srinivasa Ramanujan was one of India's greatest mathematical geniuses. He made substantial contributions to the analytical theory of numbers and worked on elliptic functions, continued fractions, and infinite series.

Ramanujan was born in his grandmother's house in Erode, a small village about 400 km southwest of Madras. When Ramanujan was a year old his mother took him to the town of Kumbakonam, about 160 km nearer Madras. His father worked in Kumbakonam as a clerk in a cloth merchant's shop. In December 1889 he contracted smallpox.

When he was nearly five years old, Ramanujan entered the primary school in Kumbakonam although he would attend several different primary schools before entering the Town High School in Kumbakonam in January 1898. At the Town High School, Ramanujan was to do well in all his school subjects and showed himself an able all round scholar. In 1900 he began to work on his own on mathematics summing geometric and arithmetic series.

Ramanujan was shown how to solve cubic equations in 1902 and he went on to find his own method to solve the quartic. The following year, not knowing that the quintic could not be solved by radicals, he tried (and of course failed) to solve the quintic.

It was in the Town High School that Ramanujan came across a mathematics book by G S Carr called Synopsis of elementary results in pure mathematics. This book, with its very concise style, allowed Ramanujan to teach himself mathematics, but the style of the book was to have a rather unfortunate effect on the way Ramanujan was later to write down mathematics since it provided the only model that he had of written mathematical arguments. The book contained theorems, formulae and short proofs. It also contained an index to papers on pure mathematics which had been published in the European Journals of Learned Societies during the first half of the 19th century. The book, published in 1856, was of course well out of date by the time Ramanujan used it.

By 1904 Ramanujan had begun to undertake deep research. He investigated the series ∑(1/n) and calculated Euler's constant to 15 decimal places. He began to study the Bernoulli numbers, although this was entirely his own independent discovery.

Ramanujan, on the strength of his good school work, was given a scholarship to the Government College in Kumbakonam which he entered in 1904. However the following year his scholarship was not renewed because Ramanujan devoted more and more of his time to mathematics and neglected his other subjects. Without money he was soon in difficulties and, without telling his parents, he ran away to the town of Vizagapatnam about 650 km north of Madras. He continued his mathematical work, however, and at this time he worked on hypergeometric series and investigated relations between integrals and series. He was to discover later that he had been studying elliptic functions.

In 1906 Ramanujan went to Madras where he entered Pachaiyappa's College. His aim was to pass the First Arts examination which would allow him to be admitted to the University of Madras. He attended lectures at Pachaiyappa's College but became ill after three months study. He took the First Arts examination after having left the course. He passed in mathematics but failed all his other subjects and therefore failed the examination. This meant that he could not enter the University of Madras. In the following years he worked on mathematics developing his own ideas without any help and without any real idea of the then current research topics other than that provided by Carr's book.

Continuing his mathematical work Ramanujan studied continued fractions and divergent series in 1908. At this stage he became seriously ill again and underwent an operation in April 1909 after which he took him some considerable time to recover. He married on 14 July 1909 when his mother arranged for him to marry a ten year old girl S Janaki Ammal. Ramanujan did not live with his wife, however, until she was twelve years old.

Ramanujan continued to develop his mathematical ideas and began to pose problems and solve problems in the Journal of the Indian Mathematical Society. He devoloped relations between elliptic modular equations in 1910. After publication of a brilliant research paper on Bernoulli numbers in 1911 in the Journal of the Indian Mathematical Society he gained recognition for his work. Despite his lack of a university education, he was becoming well known in the Madras area as a mathematical genius.

In 1911 Ramanujan approached the founder of the Indian Mathematical Society for advice on a job. After this he was appointed to his first job, a temporary post in the Accountant General's Office in Madras. It was then suggested that he approach Ramachandra Rao who was a Collector at Nellore. Ramachandra Rao was a founder member of the Indian Mathematical Society who had helped start the mathematics library. He writes in [30]:-

A short uncouth figure, stout, unshaven, not over clean, with one conspicuous feature-shining eyes- walked in with a frayed notebook under his arm. He was miserably poor. ... He opened his book and began to explain some of his discoveries. I saw quite at once that there was something out of the way; but my knowledge did not permit me to judge whether he talked sense or nonsense. ... I asked him what he wanted. He said he wanted a pittance to live on so that he might pursue his researches.

Ramachandra Rao told him to return to Madras and he tried, unsuccessfully, to arrange a scholarship for Ramanujan. In 1912 Ramanujan applied for the post of clerk in the accounts section of the Madras Port Trust. In his letter of application he wrote [3]:-

I have passed the Matriculation Examination and studied up to the First Arts but was prevented from pursuing my studies further owing to several untoward circumstances. I have, however, been devoting all my time to Mathematics and developing the subject.

Despite the fact that he had no university education, Ramanujan was clearly well known to the university mathematicians in Madras for, with his letter of application, Ramanujan included a reference from E W Middlemast who was the Professor of Mathematics at The Presidency College in Madras. Middlemast, a graduate of St John's College, Cambridge, wrote [3]:-

I can strongly recommend the applicant. He is a young man of quite exceptional capacity in mathematics and especially in work relating to numbers. He has a natural aptitude for computation and is very quick at figure work.

On the strength of the recommendation Ramanujan was appointed to the post of clerk and began his duties on 1 March 1912. Ramanujan was quite lucky to have a number of people working round him with a training in mathematics. In fact the Chief Accountant for the Madras Port Trust, S N Aiyar, was trained as a mathematician and published a paper On the distribution of primes in 1913 on Ramanujan's work. The professor of civil engineering at the Madras Engineering College C L T Griffith was also interested in Ramanujan's abilities and, having been educated at University College London, knew the professor of mathematics there, namely M J M Hill. He wrote to Hill on 12 November 1912 sending some of Ramanujan's work and a copy of his 1911 paper on Bernoulli numbers.

Hill replied in a fairly encouraging way but showed that he had failed to understand Ramanujan's results on divergent series. The recommendation to Ramanujan that he read Bromwich's Theory of infinite series did not please Ramanujan much. Ramanujan wrote to E W Hobson and H F Baker trying to interest them in his results but neither replied. In January 1913 Ramanujan wrote to G H Hardy having seen a copy of his 1910 book Orders of infinity. In Ramanujan's letter to Hardy he introduced himself and his work [10]:-

I have had no university education but I have undergone the ordinary school course. After leaving school I have been employing the spare time at my disposal to work at mathematics. I have not trodden through the conventional regular course which is followed in a university course, but I am striking out a new path for myself. I have made a special investigation of divergent series in general and the results I get are termed by the local mathematicians as 'startling'.

Hardy, together with Littlewood, studied the long list of unproved theorems which Ramanujan enclosed with his letter. On 8 February he replied to Ramanujan [3], the letter beginning:-

I was exceedingly interested by your letter and by the theorems which you state. You will however understand that, before I can judge properly of the value of what you have done, it is essential that I should see proofs of some of your assertions. Your results seem to me to fall into roughly three classes:

(1)  there are a number of results that are already known, or easily deducible from known theorems;

(2)  there are results which, so far as I know, are new and interesting, but interesting rather from their curiosity and apparent difficulty than their importance;

(3)  there are results which appear to be new and important...

Ramanujan was delighted with Hardy's reply and when he wrote again he said [8]:-

I have found a friend in you who views my labours sympathetically. ... I am already a half starving man. To preserve my brains I want food and this is my first consideration. Any sympathetic letter from you will be helpful to me here to get a scholarship either from the university of from the government.

Indeed the University of Madras did give Ramanujan a scholarship in May 1913 for two years and, in 1914, Hardy brought Ramanujan to Trinity College, Cambridge, to begin an extraordinary collaboration. Setting this up was not an easy matter. Ramanujan was an orthodox Brahmin and so was a strict vegetarian. His religion should have prevented him from travelling but this difficulty was overcome, partly by the work of E H Neville who was a colleague of Hardy's at Trinity College and who met with Ramanujan while lecturing in India.

Ramanujan sailed from India on 17 March 1914. It was a calm voyage except for three days on which Ramanujan was seasick. He arrived in London on 14 April 1914 and was met by Neville. After four days in London they went to Cambridge and Ramanujan spent a couple of weeks in Neville's home before moving into rooms in Trinity College on 30th April. Right from the beginning, however, he had problems with his diet. The outbreak of World War I made obtaining special items of food harder and it was not long before Ramanujan had health problems.

Right from the start Ramanujan's collaboration with Hardy led to important results. Hardy was, however, unsure how to approach the problem of Ramanujan's lack of formal education. He wrote [1]:-

What was to be done in the way of teaching him modern mathematics? The limitations of his knowledge were as startling as its profundity.

Littlewood was asked to help teach Ramanujan rigorous mathematical methods. However he said ([31]):-

... that it was extremely difficult because every time some matter, which it was thought that Ramanujan needed to know, was mentioned, Ramanujan's response was an avalanche of original ideas which made it almost impossible for Littlewood to persist in his original intention.

The war soon took Littlewood away on war duty but Hardy remained in Cambridge to work with Ramanujan. Even in his first winter in England, Ramanujan was ill and he wrote in March 1915 that he had been ill due to the winter weather and had not been able to publish anything for five months. What he did publish was the work he did in England, the decision having been made that the results he had obtained while in India, many of which he had communicated to Hardy in his letters, would not be published until the war had ended.

On 16 March 1916 Ramanujan graduated from Cambridge with a Bachelor of Science by Research (the degree was called a Ph.D. from 1920). He had been allowed to enrol in June 1914 despite not having the proper qualifications. Ramanujan's dissertation was on Highly composite numbers and consisted of seven of his papers published in England.

Ramanujan fell seriously ill in 1917 and his doctors feared that he would die. He did improve a little by September but spent most of his time in various nursing homes. In February 1918 Hardy wrote (see [3]):-

Batty Shaw found out, what other doctors did not know, that he had undergone an operation about four years ago. His worst theory was that this had really been for the removal of a malignant growth, wrongly diagnosed. In view of the fact that Ramanujan is no worse than six months ago, he has now abandoned this theory - the other doctors never gave it any support. Tubercle has been the provisionally accepted theory, apart from this, since the original idea of gastric ulcer was given up. ... Like all Indians he is fatalistic, and it is terribly hard to get him to take care of himself.

On 18 February 1918 Ramanujan was elected a fellow of the Cambridge Philosophical Society and then three days later, the greatest honour that he would receive, his name appeared on the list for election as a fellow of the Royal Society of London. He had been proposed by an impressive list of mathematicians, namely Hardy, MacMahon, Grace, Larmor, Bromwich, Hobson, Baker, Littlewood, Nicholson, Young, Whittaker, Forsyth and Whitehead. His election as a fellow of the Royal Society was confirmed on 2 May 1918, then on 10 October 1918 he was elected a Fellow of Trinity College Cambridge, the fellowship to run for six years.

The honours which were bestowed on Ramanujan seemed to help his health improve a little and he renewed his effors at producing mathematics. By the end of November 1918 Ramanujan's health had greatly improved. Hardy wrote in a letter [3]:-

I think we may now hope that he has turned to corner, and is on the road to a real recovery. His temperature has ceased to be irregular, and he has gained nearly a stone in weight. ... There has never been any sign of any diminuation in his extraordinary mathematical talents. He has produced less, naturally, during his illness but the quality has been the same. ....

He will return to India with a scientific standing and reputation such as no Indian has enjoyed before, and I am confident that India will regard him as the treasure he is. His natural simplicity and modesty has never been affected in the least by success - indeed all that is wanted is to get him to realise that he really is a success.

Ramanujan sailed to India on 27 February 1919 arriving on 13 March. However his health was very poor and, despite medical treatment, he died there the following year.

The letters Ramanujan wrote to Hardy in 1913 had contained many fascinating results. Ramanujan worked out the Riemann series, the elliptic integrals, hypergeometric series and functional equations of the zeta function. On the other hand he had only a vague idea of what constitutes a mathematical proof. Despite many brilliant results, some of his theorems on prime numbers were completely wrong.

Ramanujan independently discovered results of Gauss, Kummer and others on hypergeometric series. Ramanujan's own work on partial sums and products of hypergeometric series have led to major development in the topic. Perhaps his most famous work was on the number p(n) of partitions of an integer n into summands. MacMahon had produced tables of the value of p(n) for small numbers n, and Ramanujan used this numerical data to conjecture some remarkable properties some of which he proved using elliptic functions. Other were only proved after Ramanujan's death.

In a joint paper with Hardy, Ramanujan gave an asymptotic formula for p(n). It had the remarkable property that it appeared to give the correct value of p(n), and this was later proved by Rademacher.

Ramanujan left a number of unpublished notebooks filled with theorems that mathematicians have continued to study. G N Watson, Mason Professor of Pure Mathematics at Birmingham from 1918 to 1951 published 14 papers under the general title Theorems stated by Ramanujan and in all he published nearly 30 papers which were inspired by Ramanujan's work. Hardy passed on to Watson the large number of manuscripts of Ramanujan that he had, both written before 1914 and some written in Ramanujan's last year in India before his death.

The picture above is taken from a stamp issued by the Indian Post Office to celebrate the 75th anniversary of his birth.