History of Science-3.
William Gilbert.
Galilieo Galilei.
The scientific method of comparing hypothesis with experiments and observations,
is expressed in the work of Gilbert in England and Galileo in Italy.
Gilbert is less well known.
He was born earlier than Galileo, and deserves the title of ‘First scientist’.
Gilbert was born in 1544, in a prominent family.
He went to Cambridge in 1558.
He completed his B.A. in 1560, M.A. in 1564, and M.D. in 1569.
He became a fellow of the Royal college of physicians in 1573.
He was elected as its president in 1599.
The following year he became the personal physician to Queen Elizabeth 1.
He was later knighted by her.
He was also physician to James 1, who succeeded her in 1603.
He died soon after in 1603.
In spite of being a famous medical man, Gilbert made his mark in physics,
through his thorough investigation of the nature of magnetism.
He was first interested in chemistry or alchemy.
He realised that transmutation of metals was a fantasy.
He then switched to study electricity and magnetism.
After 18 years of study, he published a book called ‘De Magnete’.
He disproved by experiment many old mystical beliefs about magnetism.
One such belief that a naturally occurring magnetic ore, called lodestone, could cure headaches.
He invented the technique of magnetising pieces of metal using lodestone.
He showed that the Earth itself acts like a giant bar magnet.
He gave the names ‘north pole’, and ‘south pole’.
His investigations were so thorough, that nothing new was added to scientific knowledge,
for two centuries, until the discovery of electro magnetism in the 1820’s.
He supported the Copernican model, partly because he thought,
the planets are held in orbit by magnetism.
He explained the precession of the equinoxes.
He also suggested that stars are at different distances from the Earth,
and not attached to a crystal sphere.
He even thought that stars could be Sun like bodies, with their own habitable planets.
He investigated static electricity by rubbing objects of amber or glass with silk.
He realised that there was a distinction between electricity and magnetism.
In fact he coined the word ‘electric’.
It was only in 1730 that French physicists Charles discovered positive and negative charges,
which behaved in some way like magnetic poles.
The most important feature of De Magnete was not what Gilbert discovered,
but how he discovered it.
He set out a clear scientific method as an example for others to follow.
De Magnete inspired Galileo to carry out his own investigations into magnetism.
Galileo’s key contributions to the birth of science lay precisely in emphasising the need for accurate,
repeated experiments to test hypotheses.
Galileo was born in Pisa in 1564, the same year as Shakesphere.
Galileo’s father was an accomplished professional musician, interested in mathematics and musical theory.
He married a young women called Giulia in 1562.
Galileo was the eldest of seven children, three of whom died in infancy.
Until he was eleven, Galileo was educated at home, mostly by his father.
He became an excellent musician.
He only played mostly the lute, for pleasure throughout his life.
His father sent him to a monastery near Florence for his formal education.
Galileo fell in love with the monastic way of life, and joined the order as a novice at the age of 15.
His father did not want him to become a monk, and withdrew him from the monastery.
In 1581, at the age of 17, Galileo was enrolled as a medical student, at the university of Pisa.
As a student Galileo was argumentative, and unafraid to question the Aristotelian wisdom of the time.
One such Aristotelian idea was different weights fall at different speeds.
Galileo observed that hailstones in different sizes reached the ground at the same time.
Galileo pointed out to his teachers, that all hailstones are made in the same place in the cloud,
so they all fall together at the same speed, whatever their weight.
In 1583, Galileo attended a lecture given by Ricci, the court mathematician.
Galileo was fascinated.
He joined Ricci’s students on a informal basis, and began to study Euclid instead of his medical text books.
Ricci asked Galileo’s father whether he could switch from medicine to mathematics.
His father refused, saying there were many jobs for physicians, but very few for mathematicians.
Galileo carried on studying mathematics, ignoring his medical courses.
He had to leave Pisa in 1585, without any degree.
Galileo tried to make a living, as a private tutor in mathematic and natural philosophy.
It was at this time, that Galileo became mesmerised by the slow steady swing of the chandelier,
in the cathedral.
The sermon was very dull, and he timed the swing of the pendulum using his pulse.
This led him to discover that the pendulum always took the same time to complete one swing,
whether it was swinging over a short arc or a long arc.
The idea remained idle for several years.
In 1602, careful experiments were done with pendulums by Galileo.
It was proved that the period of swing of a pendulum depends only on its length,
and not on the weight of the pendulum, or the arc it is swinging through.
Initially Galileo could barely make a living, with his meager income.
An aristocrat, Del monte who was interested in science came to his rescue.
In 1589, with Del monte’s influence, he became a professor of mathematics in the university of Pisa.
His father was not impressed by this post.
He pointed out to Galileo that a professor of medicine, received a salary of 2000 crowns per year,
while a professor of mathematics received only 60.
Galileo had to supplement his income by tutoring students.
Only the sons of rich could afford tuitions.
When they grew up, they helped spread his fame in the right circles.
Though he was professor of mathematics, he had to teach physics,
which at that time was called natural philosophy.
The official syllabus was based on Aristotle.
Galileo reluctantly taught this in his official lectures.
In private he discussed new and unconventional ideas.
He even wrote a draft of a book with his ideas, but refrained from publishing it,
because he was not well established.
The story that Galileo dropped two different weights, from the leaning tower of Pisa,
to show that they would arrive at the ground, at the same time, is not true.
Galileo never fitted in the university of Pisa.
He was anti establishment.
He had a full head of red hair, and a substantial red beard,
and could be found fraternising with students in seedy bars.
When his father died, the need for better income became more pressing.
His father had promised a generous dowry for his daughter Virginia.
When he died Galileo and his brother became responsible for the debt.
His brother not only failed to pay his share, but took loans from Galileo, which he never returned.
Galileo himself was fond of fine wines and good food, and he liked to entertain his friends.
Galileo got a new job at the university of Padua, in the Venetian Republic,
which had a reputation for encouraging new ideas.
He got a salary of 180 crowns per year.
Galileo took up the post in 1592, when he was 28 years old.
Galileo spent 18 years in Padua, which he considered as the happiest years of his life.
Galileo wrote a treatise on military fortification for the Venetian Republic.
He published a book on mechanics.
His social and intellectual life flourished in Padua.
He was constantly worried about money.
He tried to solve his financial problems by inventing something that would make him rich.
He tried unsuccessfully to invent a thermometer.
He invented a device that could be used as a calculator.
It served as a pocket calculator of those times.
It was used to calculate exchange rates, compound interest etc.,.
In the 1590’s the instrument called the compass was selling very well.
The compass was priced cheaply, but a healthy tuition fee was charged, to teach how to use it.
This did not last long, because other people copied the idea.
During this time he established a stable relationship with Marina, who was from a lower social class.
The two never married, or lived in the same house.
The couple however, produced 2 daughters and a son.
The son was to become Galileo’s heir.
The daughter’s were to become nuns, maybe to avoid paying dowry.
In 1603, Galileo suffered an illness that affected him for the rest of his life.
He suffered from repeated bouts of an arthritic ailment for the rest of his life.
By the time he was forty in 1604, Galileo had established himself,
as a natural philosopher and mathematician.
He was leading a full and happy life in Padua.
He carried out his famous experiments with pendulums and balls rolling down inclined planes.
He established that objects with different weights do accelerate at the same rate.
Galileo always carried out experiments to test hypothesis.
He investigated hydrostatics.
He followed the work of Gilbert and studied magnetic phenomena.
He corresponded with other natural philosophers including Kepler.
In a letter written to Kepler in 1597, he stated his enthusiasm for the copernican model.
He had a full private life.
He studied literature and poetry.
He attended the theatre and continued to play the lute to high standard.
His salary was increased to a level he could live comfortably.
But, he was not able to save, for his retirement.
In 1604, Galileo’s stature further increased, when the supernova studied by Kepler appeared.
Galileo turned himself into an astronomer.
Using careful surveying techniques he established,
that the new star showed no motion relative to other stars.
He gave a series of well received public lectures, stating that this new star,
must be as far away from the Earth as other stars.
This refuted the Aristotelian notion of an unchanging celestial sphere.
He even wrote a poem about it.
While Galileo’s public reputation increased, his private life began to pose problems.
In 1605, both his brother-in-laws were suing him for non payment of dowries of his sisters.
He had to go to Florence to argue his case.
At this time a dutchees called Christina, invited Galileo to instruct her teenage son Cosimo,
in the use of his compass, and mathematics and general.
Perhaps due to the influence of the duchess, the cases against him was dropped,
at least for the time being.
Galileo was tiring of his lecturing duties.
He wanted to do more of experiments and write.
He was contemplating major changes to his life,
and also gathering material from his experimental work, for a planned book.
At this time the political situation in Italy changed dramatically.
In 1605, Paul 5 was elected as the Pope.
He wanted to extend the authority of the church, and tighten the papal grip, on catholic states.
However he lacked powerful armies on his own.
Venice was a particular thorn in his flesh.
The pope excommunicated the Doge of Venice, and all his officials.
Venice ignored the excommunication.
The possibility of war loomed.
Catholics Spain lined up to support the pope.
Protestant France offered aid to Venice.
Tensions eased after a few months.
In 1608, Galileo was severely afflicted with his arthritic complaint.
In spite of the difficulties he continued to prepare his epic book on mechanics, inertia and motion.
At this time, Galileo proved that an object thrown in the air, follows a parabolic path.
In the beginning of the 17th century people still thought, that if a ball fired horizontally from a cannon,
would fly a certain distance in a straight line and then fall vertically to the ground.
Galileo proved that the path was always parabolic, regardless of the speed and weight of the cannon ball.
Hans who was a spectacle maker in Holland, discovered the telescope by chance.
Galileo realised that an instrument, that could make distant objects visible,
would be of enormous military and trade importance to Venice.
Galileo was keen to develop this idea for his own benefit.
At that time he only knew that the instrument involved two lenses in a tube.
He managed to build his own telescope.
The dutch telescope used two concave lenses, giving an upside down image.
Galileo used one concave lens and one convex lens to give an upright image.
He built a telescope with a magnifying power 10 times that of the dutch version.
He gave a presentation to the senate in Venice.
He gave the telescope as a gift to the Doge of Venice.
In return he got a post at the university of Pisa, with double the salary of 1000 crowns a year.
By 1609, he made a telescope with a magnifying power of 20 times.
He sent one of these telescopes to Kepler, to use and verify Galileo’s discovery.
Using his telescope Galileo discovered the four largest and brightest moons of Jupiter in 1610.
It is known to astronomers today as the Galilean satellites of Jupiter.
Using the same telescope he discovered that the surface of the moon, is not a smooth sphere,
as Aristotle believed, but had craters, and mountain ranges several kilometres high.
He estimated the height of the mountains from the length of their shadows, on the moon’s surface.
He presented his findings in a book called the starry messenger in 1610.
He became famous because of his book, throughout the educated world.
Galileo has given the post of chief mathematician at the university of Pisa.
He was also appointed as the mathematician and philosopher to the grand duke of Tuscany, for life,
with a salary of 1000 crowns per year.
He had no teachings duties.
He was also released from paying outstanding dowries.
At this time news reached him that Kepler had observed the 4 satellite of Jupiter.
A big change occurred in his life.
He split with his wife Marina amicably.
The astrological observations were direct evidence of the accuracy of the Copernican model.
Using Jupiter’s moons as an example, Galileo showed that it was possible for the Earth’s moon,
to stay in orbit around the Earth, even if the Earth was moving.
He noticed that Saturn was not a perfect sphere.
He discovered the phases of Venus, similar to the phases of the moon.
These phases could be explained only if Venus orbits the sun.
The Aristotelian simply refused to accept what was seen through the telescope.
They thought it was some artefact produced by the lens in the telescope.
Galileo was however clear that what he saw was real.
Galileo also observed dark features of sunspots in the sun.
Galileo was careful not to endorse the Copernican model publicly.
He feared for his life.
He preferred to present the evidence, and let it speak for itself.
He felt that sooner or later the church would accept the implications.
In 1611, Galileo went to Rome, and met pope Paul 5.
He was allowed to address the pope standing, and not kneeling.
A scientific subcommittee was formed of learned priests, to examine Galileo’s claims.
The subcommittee concluded that,
- the milky way had a vast number of stars.
- Saturn has a strange oval shape.
- the moon’s surface is irregular.
- Venus has phases.
- Jupiter had 4 satellites.
All this became official.
But no mention was made of the implications of these observations.
While in Rome Galileo became a member of what is regarded as the first scientific society in the world.
It was called the Lyncean academy.
This is where the name ‘telescope’ was suggested for his magnifying device.
Galileo had that habit of verifying all his theories with experiments.
This was still a novelty in 1611.
This was what qualifies him in many ways, to be the first scientist.
Galileo was very cautious about what he put down in print, about the Copernican model.
But in private letters he made it clear, that he thought that the sun was at the centre,
and Earth rotates itself, and moves around the sun.
This was against biblical teachings.
Galileo’s caution slipped just once in 1613.
The Lyncean academy published his book about sunspots.
In the appendix to the book, Galileo clearly and unambiguously supported Copernican ideas.
He used the example of Jupiter’s moons to support his ideas.
This attracted criticism from many people.
Galileo went to Rome in 1615.
Pope Paul 5, set up a papal commission to investigate Galileo’s Copernican ideas.
The commission concluded that the idea, that the sun is at the centre of the universe,
is foolish, absurd and heretical.
The pope sent word to Galileo, that he should not hold or defend this idea.
The inquisition was the notorious judicial arm of the Papacy, to combat heresy.
He was summoned by the inquisition, and warned that he should not hold,
defend or teach Copernican ideas.
Galileo did not object.
Galileo thought that he was safe, at least for the time being, and returned to Tuscany.
Galileo was plagued by illnesses.
He continued his scientific work in his 50’s and 60’s.
His daughters joined a convent, to become nuns.
Galileo saw this as the only practical way, because his daughters were illegitimate,
and no respectable man, would marry them, without a large dowry.
Galileo had no intention to get into the dowry business again.
He was fond of his daughters, and visited them often.
In 1620’s the 30 year war, temporarily shifted in favour of the catholic side.
Galileo received permission to publish a book called ‘The Assayer’.
A new Pope Urban 8 was elected.
The Lynceans dedicated the book, The Assayer to the Pope.
The pope was delighted.
In 1624, Galileo travelled to Rome to meet the Pope.
He was granted 6 audiences with the Pope.
He was awarded a gold medal and other honours.
The greatest honour was the permission of the Pope to write a book about the two models of the universe.
The Ptolemaic model and the Copernican model.
There was a stipulation that he should not argue in favour of the Copernican model.
He was allowed to teach the Copernican model, but not to defend it.
The book took a long time to write.
During this time Galileo invented a compound microscope.
It involved two lenses ground with a double convex shape.
He did pioneering work in microscopy.
In 1625, he published a book, with detailed illustrations of insects, seen with a microscope.
Galileo’s book, ‘Dialogue on the two chief world systems’ was finished in 1629.
The dialogue was a debate between two people of the two models.
One person in the dialogue supports the Ptolemaic model, and another person the Copernican model.
The concept of the dialogue dated back to the Greeks.
It was a way to teach unconventional ideas, without endorsing them.
The third voice was a that of an impartial commentator.
The commentator in the book tended to support the Copernican system.
Galileo delivered the manuscript to Riccardi, a priest in Rome, in 1630.
The book was censored by Riccardi, who conditionally passed it.
Riccardi wanted a new preface and conclusion to the book.
The conclusion had to spell out that the Copernican model was only a hypothesis.
Riccardi sent the changes to the book, adding that the author may alter or embellish the wording,
as long as the substance is preserved.
Galileo took this at face value which turned out to be a big mistake.
Due to the plague, which occurred at that time, the book went on sale only in 1632.
A few copies were sent to Rome.
Cardinal Barberini, the nephew of the Pope wrote to Galileo that he enjoyed the book.
Many others were not so pleased.
Galileo made some changes in the conclusion.
The censor had wanted the conclusion to state that the Copernican model was only hypothetical.
One of the two people in the dialogue of the book was Simplicio, who supported the Ptolemaic model.
Galileo put the conclusion that the Copernican model was hypothetical in the words of Simplicio.
People close to the Pope suggested to him, that Galileo had done this,
to imply that the Pope was a Simpleton.
This infuriated the Pope.
A papal commission was setup to look into the alligetations.
The Jesuits commission was keen on finding Galileo guilty.
They dug up the old instruction, that Galileo should not ‘hold, defend or teach’, the Copernican model.
This was enough for Pope Urban 8, to summon Galileo to stand trial for heresy.
Galileo pleaded old age and illness to delay the trip to Rome for the trial.
He eventually went to Rome in 1633.
He had to spend 3 weeks in quarantine in the Tuscan border because of the plague.
In the trial he was accused of various minor offences.
One example, that he had written the book in Italian and not Latin,
so that the common man could read.
The key issue was whether Galileo had disobeyed a papal injuction not to teach the Copernican system.
Galileo had a letter from Cardinal Bellarmine, stating that he should not hold or defend Copernican views,
but he was not constrained in any other way.
The inquisition had very little evidence against him.
The problem was that to bring a false charge of heresy, was as serious a crime as heresy.
If Galileo was not guilty, his accuser were.
The accusers were the highest authorities of the catholic church.
Cardinal Barberini, who acted in Galileo’s best interest persuaded him to confess,
even if he was not guilty.
He was likely to be tortured.
Galileo was 69 years old, suffering from arthritis, and terrified of torture.
He confessed that, he did not believe in the Copernican system, to escape torture.
He was given a sentence of life imprisonment.
Thanks to Barberini, the sentence was gradually softened.
First house arrest, in the Tuscan embassy in Rome,
then to the custody of an Archbishop,
and finally to confinement in his own house in 1634.
Isolated, Galileo completed his greatest book, ‘The two sciences’.
The book summed up his life’s work on mechanics, inertia, the science of moving things,
and the science of non moving things.
It also spelt out the scientific method.
It was the first scientific textbook, which spelt out that the universe is governed by laws,
which can be understood by the human mind.
Its laws is driven by forces, but can be calculated using mathematics.
The book was smuggled out of Italy and published in Leiden, in the Netherlands.
The book had an enormous influence on the development of science in Europe, expect Italy.
This was due to the condemnation by a church of Rome of Galileo’s works.
Italy which had seen the first flowering of the Renaissance, became the back water for scientific progress.
By the time ‘The two sciences’ was published, Galileo had gone blind.
Even after that, he thought up an idea for an escapement for a pendulum clock.
He explained this to his son, Vincenzio, who built such a clock after he died.
Similar clocks spread across Europe following the independent work of Huygens.
Vincenzo acted as Galileo’s assistant and scribe.
He would later write the biography of Galileo, spreading many of the legends of Galileo,
that colour the popular view of the great man today.
Galileo died peacefully in his sleep, in 1642, just short of his 78th birthday.
Galileo was the first scientist to fully understand that our experiments,
are always an imperfect representation of an idealised world of pure science.
In the centuries after Galileo, experimentation became a standard feature for scientific approach.
This would involve breaking down complex systems into simple components obeying idealised rules,
to start with.
Accepting that there would be errors in the predictions in the simple models,
caused by complications outside the scope of the models.
In the case of experiments with rolling and falling balls, friction and wind resistance,
were the complications which caused small errors in the observations.
Galileo extended the rolling balls in the inclined plane experiment.
The balls rolled down an inclined plane, and climbed up another inclined plane.
If the angles were same, the balls climbed up almost to the same height.
Galileo made the second plane shallower and shallower.
When the second plane was horizontal, the ball would almost roll forever.
Only friction would slow it down.
Galileo realised that moving objects tend to keep moving, unless they are affected by friction,
or some other outside force.
This would be a key component in the flowering of mechanics, achieved by Newton.
There was one imperfection in Galileo’s work.
He knew that the Earth was round.
So horizontal motion actually means following a curved path.
Galileo thought that inertial motion, without any external force,
basically involved moving in a circle.
This seemed to him, to explain why planets stayed in orbit around the sun.
Descartes was a key figure between Galileo and Newton.
He realised that moving objects tends, as a result of inertia, to keep moving in a straight line,
unless it is acted upon by a force.
Galileo laid the foundation of science, and pointed the way for others.
But, there was plenty for others to do in building on this foundation.