The Sun is the Center of the Universe

The Sun is the centre of the universe and planets revolve around it.

• Who discovered it: Nicholaus Copernicus
• Year of the Discovery: A.D. 1520

How was it Discovered?

In 1499 Copernicus graduated from the University of Bologna, Italy; was ordained as a priest in the Catholic Church; and returned to Poland to work for his uncle. He was given the top room in a cathedral tower so he could continue his astronomy measurements.

At that time people still believed a model of the universe created by the Greek scientist, Ptolemy, more than 1500 years earlier. According to Ptolemy, the earth was the centre of the universe and never moved. The sun and the planets revolved around the earth in great circles, while the distant stars perched way out on the great spherical shell of space.

Copernicus hoped to use “modern” (sixteenth century) technology to improve on Ptolemy’s measurements. For almost 20 years Copernicus painstakingly measured the position of the planets each night. But his tables of findings still made no sense in Ptolemy’s model.

Over the years, Copernicus began to wonder what the movement of the planets would look like from another moving planet. When his calculations based on this idea more accurately predicted the planets’ actual movements, he began to wonder what the motion of the planets would look like if the earth moved. Immediately, the logic of this notion became apparent.

Each planet appeared at different distances from the earth at different times throughout a year. Copernicus realized that this meant Earth could not lie at the centre of the planets’ circular paths.

From 20 years he discovered that only the sun didn’t vary in apparent size. This means that the distance between the earth and the sun had to always remain the same.

The whole world and especially the all-powerful Catholic Church, believed in the Earth is the centre of the universe, so for fear of retribution from the church, he dared not to release his findings during his lifetime. They were made public in 1543.

Levers and Buoyancy

• Who discovered it: Archimedes
• Year of the Discovery: 260 B.C.

How was it Discovered?

1st: Levers:

In 260 B.C. 26-year-old Archimedes studied the two known sciences – astronomy and geometry – in Syracuse, Sicily. One day Archimedes was distracted by four boys playing on the beach with a driftwood plank. They balanced the board over a waist-high rock. One boy straddled one end while his three friends jumped hard onto the other. The lone boy was tossed into the air

Archimedes was fascinated. And he determined to understand the principles that so easily allowed a small weight (one boy) to lift a large weight (three boys).

Archimedes used a trip of wood and small wooden blocks to model the boys and their driftwood. He made a triangular block to model their rock. By measuring as he balanced different combinations of weights on each end of the lever (lever came from the Latin word meaning “to lift”), Archimedes realized that levers were an example of one of Euclid’s proportions at work. The force (weight) pushing down on each side of the lever had to proportional to the lengths of the board on each side of the balance point. He had discovered the mathematical concept of levers, the most common and basic lifting system ever devised.

2nd: Buoyancy:

Fifteen years later, in 245 B.C., Archimedes was ordered by King Hieron to find out whether a goldsmith has cheated the king. Hieron had given the smith a weight of gold and asked him to fashion a solid-gold crown. Even though the crown weighed exactly the same as the original gold, the king suspected that the goldsmith has wrapped a thin layer of gold around some cheap metal inside. Archimedes was ordered to discover whether the crown was solid gold without damaging the crown itself.

It seemed like an impossible task. In a public bathhouse, Archimedes noticed his arms floating on the water’s surface. A vague idea began to form in his mind. He pulled his arm completely under the surface. Then he relaxed and it floated back up.

He stood up in the tub. The water level dropped around the tub’s sides. He sat back down. The water level rose.

He lay down. The water rises higher, and he realized that he felt lighter. He stood up. The water level fell and he felt heavier. Water had to be pushing up on his submerged body to make it feel lighter.

He carried a stone and a block of wood of about the same size into the tub and submerged them both. The stone sank but felt lighter. He had to push the wood down to submerge it. That meant that water pushed up with a force related to the amount of water displaced by the object (the object’s size) rather than to the object’s weight. How heavy the object felt in water had to relate to the object’s density (how much each unit volume of it weighed).

That showed Archimedes how to answer the king’s question. He returned to the king. The key was density. If the crown was made of other metal than gold, it could weigh the same but would have a different density and thus occupy a different volume.

The crown and an equal weight of gold were dunked into a bowl of water. The crow displaced more water and was thus shown to be fake.

More important, Archimedes discovered the principle of buoyancy: Water pushes up on objects with a force equal to the amount of water the objects displace.

Human Anatomy

The first scientific, accurate guide to human anatomy

• Who discovered it: Andreas Vesalius
• Year of the discovery: 1543

How was it Discovered?

Andreas Vesalius was born in Brussels in 1515. His father, a doctor in the royal court, had collected an exceptional medical library. Young Vesalius poured over each volume and showed immense curiosity about the functioning of living things. He often caught and dissected small animals and insects.

At the age of 18 Vesalius traveled to Paris to study medicine. Physical dissection of animal or human bodies was not a common part of the accepted medical study. If a dissection had to be performed, professors lectured while a barber did the actual cutting. Anatomy was taught from the drawings and translated texts of Galen, a Greek doctor whose texts were written in 50 B.C.

Vesalius was quickly recognized as brilliant but arrogant and argumentative. During the second dissection he attended, Vesalius snatched the knife from the barber and demonstrated both his skill at dissection and his knowledge of anatomy, to the amazement of all in attendance.

As a medical student, Vesalius be came a ring leader, luring his fellow students to raid the boneyards of Paris for skeletons to study and graveyards for bodies to dissect. Vesalius regularly braved vicious guard dogs and the gruesome stench of Paris’s mound of Monfaucon (where the bodies of executed criminals were dumped) just to get his hands on freshly killed bodies to study.

In 1537 Vesalius graduated and moved to the University of Padua (Italy), where he began a long series of lectures each centered on actual dissections and tissue experiments. Students and other professors flocked to his classes, fascinated by his skill and by the new reality he uncovered muscles, arteries, nerves, veins, and even thin structures of the human brain.

This series culminated in January 1540, with a lecture he presented to a packed theater in Bologna, Italy. Like all other medical students, Vesalius had been trained to believe in Galen’s work. However, Vesalius had long been troubled be cause so many of his dissections revealed actual structures that differed from Galen’s descriptions.

In this lecture, for the first time in public, Vesalius revealed his evidence to discredit Galen and to show that Galen’s descriptions of curved human thigh bones, heart chambers, segmented breast bones, etc., better matched the anatomy of apes than humans. In his lecture, Vesalius detailed more than 200 discrepancies between actual human anatomy and Galen’s descriptions. Time after time, Vesalius showed that what every doctor and surgeon in Europe relied on fit better with apes, dogs, and sheep than the human body. Galen, and every medical text based on his work, were wrong.

Vesalius stunned the local medical community with this lecture. Then he secluded himself for three years preparing his detailed anatomy book. He used master artists to draw what he dissected—blood vessels, nerves, bones, organs, muscles, tendons, and brain.

Vesalius completed and published his magnificent anatomy book in 1543. When medical professors (who had taught and believed in Galen their entire lives) received Vesalius’s book with skepticism and doubt, Vesalius flew into a rage and burned all of his notes and studies in a great bon fire, swearing that he would never again cut into human tissue.

Luck ily for us, his published book survived and became the standard anatomy text for over 300 years.

The Law of Falling Objects

Objects fall at the same speed regardless of their weight

• Who discovered it: Galileo Galilei
• Year of Discovery: 1598

How was it Discovered?

Galileo Galilei, a 24-year-old mathematics professor at the University of Pisa, Italy, often sat in a local cathedral when some nagging problem weighed on his mind. Lamps gently swung on long chains to illuminate the cathedral. One day in the summer of 1598, Galileo realized that those lamps always swung at the SAME speed.

He decided to time them. He used the pulse in his neck to measure the period of each swing of one of the lamps. Then he timed a larger lamp and found that it swung at the same rate. He borrowed one of the long tapers alter boys used to light the lamps and swung both large and small lamps more vigorously. Over many days he timed the lamps and found that they always took exactly the same amount of time to travel through one complete arc. It didn’t matter how big (heavy) the lamp was or how big the arc was.

Heavy lamps fell through their arc at the same rate as lighter lamps. Galileo was fascinated. This observation contradicted a 2,000-year-old cornerstone of beliefs about the world.

He stood before his class at the University of Pisa, Italy, holding bricks as if weighing and comparing them, a single brick in one hand and two bricks that he had cemented together in the other. “Gentlemen, I have been watching pendulums swing back and forth. And I have come to a conclusion. Aristotle is wrong.”

The class gasped, “Aristotle? Wrong?!!” The first fact every schoolboy learned in beginning science was that the writings of the ancient Greek philosopher, Aristotle, were the foundation of science. One of Aristotle’s central theorems stated that heavier objects fall faster because they weigh more.

Galileo climbed on his desk, held the bricks at eye level, and let them fall. Thud! Both bricks crashed to the floor. “Did the heavier brick fall faster?” he demanded. The class shook their heads. NO, it had not. They landed together.

But the world was reluctant to hear Galileo’s truth. On seeing Galileo’s brock demonstration, friend and fellow mathematician Ostilio Ricci admitted only that “This double brick falls at the same rate this single brick. Still, I cannot so easily believe that Aristotle is wholly wrong. Search for another explanation.”

Jupiter’s Moon

Other planets (besides Earth) have moons

• Who discovered it: Galileo Galilei
• Year of Discovery: 1610

How was it Discovered?

This was a discovery made possible by an invention; the telescope. Galileo saw his first telescope in late 1608 and instantly recognized that a more powerful telescope could be the answer to the prayers of every astronomer. By late 1609 Galileo had produced a 40-power, two-lens telescope. That 1609 telescope was the first practical telescope for scientific use.

A paper by Johannes Kepler describing the orbits of the planets convinced Galileo to believe the theory of Polish astronomer Nicholaus Copernicus, who first claimed that the sun was the centre of the universe, not the earth. Believing Copernicus was a dangerous thing to do. Friar Giordano Bruno had been burned at the stake for believing Copernicus. Galileo decided to use his new telescope to prove that Copernicus was right by more accurately charting the motion of the planets.

Galileo first turned his telescope on the moon. There he clearly saw mountains and valleys. He saw deep craters with tall, jagged rims slicing like serrated knives into the lunar sky. The moon that Galileo saw was radically different from the perfectly smooth sphere that Aristotle and Ptolemy said it was (the two Greek astronomers whose teachings still formed the basis of all science in 1610). Both the all-powerful Catholic Church and every university and scientist in Europe believed Aristotle and Ptolemy.

In one night’s viewing of the moon’s surface through his telescope. Galileo proved Aristotle wrong, again. The last time Galileo’s observations had contradicted Aristotle’s teachings, Galileo had been fired from his teaching position for being right when he proved that all objects fall at the same rate regardless of their weight.

Galileo next aimed his telescope at Jupiter, the biggest planet, planning to carefully chart its motion over several months. Through his telescope (the name is a combination of the Greek words for “distant” and “looking”) Galileo saw a magnified view of the heavens no human eye had ever seen. He saw Jupiter clearly, and, to his amazement, he found moons circling the giant planet. Aristotle had said (and all scientists believed) that Earth was the ONLY planet in the universe that had a moon. Within days, Galileo discovered four of Jupiter’s moons. These were the first discovered moons other than our own.

Aristotle was Wrong … Again!

Still, old beliefs do not die easily. In 1616 the Council of Cardinals forbade Galileo ever again to teach or promote Copernicus’s theories. Many senior church officials refused to look through a telescope, claiming it was a magician’s trick and that the moons were in the telescope.

When Galileo ignored their warning, he was summoned to Rome by the Church’s all-powerful Inquisition. A gruelling trial followed. Galileo was condemned by the Church and forced publicly recant his views and findings. He was placed under house arrest for the rest of his life, dying in 1640 without hearing even one voice other than his own proclaim that his discoveries were true. The Church did not rescind the condemned of Galileo and his discoveries until October 1992, 376 years after they incorrectly condemned him!

Human Circulatory System

The first complete understanding of how arteries, veins, heart, and lungs function to form a single, complete circulatory system.

• Who discovered it: William Harvey
• Year of Discovery: 1628

How was it Discovered?

Through the sixteenth century, doctors relied on the 1,500-year-old writings of the Greek physician Galen, who said that food was converted into the blood in the liver and was then consumed by the body for fuel. Most agreed that the blood that flowed through arteries had no connection with the blood that flowed through veins.

When Harvey returned to England in 1602, he married the daughter of Queen Elizabeth’s doctor, he was appointed a physician in the court of King James I and was then appointed as a personal physician to King Charles I in 1618.

While serving the English kings, Harvey focused his studies on veins and arteries. He conducted extensive experiments with animals and human corpses. during these dissections, he discovered the series of flap valves that exist throughout the veins. He was not the first to find these valves but was the first to note that they always directed blood flow toward the heart. Blood flowed in veins only from the arms, legs, and head back to the heart.

He began a series of animal experiments in which he tied off a single artery or vein to see what happened. Sometimes he clamped an artery and later released it to see where this surge of blood will go. He did the same with veins, clamping a vein and then releasing it. Sometimes he clamped both vein and artery and then released one at a time. These experiments proved that arteries and veins were connected into a single circulatory system and that blood always flowed from arteries to veins.

Harvey turned to the heart itself and soon realized that the heart acted as a muscle and pushed blood out to lungs and out into arteries. He Followed blood as it flowed through various animals, Harvey saw that blood was not consumed, but circulated over and over again through the system, carrying air and nourishment to the body.

By 1625 Harvey had discovered an almost complete picture of the circulatory system. he faced two problems. First, he couldn’t figure out how the blood got from an artery across to a vein, even though his experiments proved that it did. The second problem Harvey faced was his fear of mob reactions, church condemnation when he said that the heart was just a muscular pump and not the house of soul and consciousness, and the press (scribes). He was afraid he’d lose his job with the king.

In 1628 Harvey found a small German publisher to publish a thin (72 pages) summary of his work and discoveries. He published it in Latin (the language of science), hoping no one in England would read it.

News of Harvey’s book raced across Europe and made him instantly notorious. He lost many patients, who were shocked by his claims. but Harvey’s science was careful and accurate. By 1650 Harvey’s Book had become the accepted textbook on the circulatory system.

 

Fun Fact: “Harvey had no microscope and so couldn’t see blood vessels as small as capillaries. By 1670, three years after Harvey’s death, Italian Marcello Malpighi had discovered capillaries with a microscope, thus completing Harvey’s circulatory system”.

Air Pressure

Air (the atmosphere) has weight and presses on us.

• Who discovered it: Evangelista Torricelli
• Year of Discovery: 1643

How was it Discovered?

On a clear October day in 1640, Galileo conducted a suction-pump experiment at a public well just off the market plaza in Florence, Italy. The famed Italian scientist lowered a long tube into the well’s murky water. From the well, Galileo’s tube draped up over a wooden cross-beam three meters above the well’s wall, and then down to hand-powered pump held by two assistants: Evangelista Torricelli, the 32-year-old the son of a wealthy merchant and an aspiring scientist, and Giovanni Baliani, another Italian physicist.

Torricelli and Baliani pumped the pump’s wooden handlebar, slowly sucking the air out of Galileo’s tube, pulling water higher into the tube. They pumped until the tube flattened like a run-over drinking straw. But no matter how hard they worked, water would NOT rise more than 9.7 meters above the well’s water level. It was the same in EVERY test.

Galileo proposed that –somehow– the weight of the water column made it collapse back to that height.

In 1643, Torricelli returned to the suction pump mystery. If Galileo was correct, a heavier liquid should reach the same critical weight and collapse at a lower height. Liquid mercury weighted 13.5 times as much as water. Thus, a column of mercury should never rise any higher than 1/13.5 the height of a water column, or about 30 inches.

Torricelli filled a six-foot glass tube with liquid mercury and shoved a cork into the open end. Then he inverted the tube and submerged the corked end in a tub of liquid mercury before he pulled out the stopper. As he expected, mercury flowed out of the tube and into the tube. But not all mercury ran out.

Torricelli measured the height of the remaining mercury column, 30 inches, as expected. Still, Torricelli suspected that the mystery’s true answer had something to do with the vacuum he had created above his column of mercury.

The next day, with wind and a cold rain lashing at the windows, Torricelli repeated his experiment, planning to study the vacuum above the mercury. However, on this day the mercury column only rose to a height of 29 inches.

Torricelli was perplexed. He had expected the mercury to rise to the same height as yesterday. What was different? Rain beat on the window as Torricelli pondered this new wrinkle.

What was different was the atmosphere, the weather. Torricelli’s mind latched onto a revolutionary new idea. Air, itself, had weight. The real answer to suction pump mystery lay not in the weight of the liquid, nor in the vacuum above it, but in the weight of the atmosphere pushing down around it.

Torricelli realized that the weight of the air in the atmosphere pushed down on the mercury in the tub. That pressure forced mercury up into the tube. The weight of the mercury in the tube had to be exactly equal to the weight of the atmosphere pushing down on the mercury in the tub.

When the weight of the atmosphere changed, it would push down wither a little bit more a little bit less on the mercury in the tub and drive the column of mercury in the tube wither a little higher or a little lower. Changing weather must change the weight of the atmosphere.

Torricelli had discovered atmospheric pressure and a way to measure and study it.

Boyle’s Law

“The volume of a gas is inversely proportional to the force squeezing it.”

* Who Discovered it: Robert Boyle.
* Year of Discovery: 1662

How was it Discovered?

Robert Boyle was the son of an earl and a member of the British Scientific Society. During a 1662 society meeting. Robert Hooke read a paper describing a French experiment on the “springiness of air”. The characteristics of air were of great interest to scientists in the seventeenth century.

French scientists built a brass cylinder fitted tightly with a piston. Several men pushed down hard on the piston, compressing the air trapped below. Then they let go. The piston sprang back up, but NOT all the way back up. The French claimed this proved that air was not perfectly springy. Once compressed, it stayed slightly compressed.

Robert Boyle claimed that the French experiment proved nothing. Their piston, he said, was too tight to bounce all the way back up. Others argued that, if they made the piston looser, air would leak around the edges and ruin the experiment.

Boyle promised to create a Perfect Piston that was neither too tight nor too loose. He also claimed that his Perfect piston would prove the French wrong.

Two weeks later Robert Boyle stood before the society with a large glass tube that he had shaped into a lopsided “U”. One side of the “U” rose over three feet high and was skinny. The other side was short and fat. The short side was sealed at the top. The tall, skinny side was open.

Boyle poured liquid mercury into his tube until it covered the bottom of the “U” and rose just a little on both sides. A large pocket of air was trapped above this mercury in the short fat side. A piston, Boyle explained, was any device that compressed air. Since his used mercury to compress air, there would be no friction to affect the results, as had been true in the French experiment.

Boyle recorded the glass piston’s weight and etched a line in the glass where mercury met the trapped air pocket. Boyle trickled liquid mercury down the long neck of the tall side of his piston until he had filled the neck. Mercury now rose well over halfway up the short side. The trapped air had been squeezed to less than half of its original volume by the weight and force of mercury.

Boyle drew a second line on the short chamber to mark the new level of mercury inside marking the compressed volume of trapped air. He then drained mercury through a valve at the bottom of the “U” until the glass piston and mercury weighed exactly the same as they had at the beginning. The mercury level returned to its exact starting line. The trapped air had sprung back exactly to where it started. Air was perfectly Springy. The French were wrong. Boyle was right.

Robert Boyle continued the experiments with his funny glass piston and noticed something quite remarkable. When he doubled the pressure (weight of mercury) on a trapped body of air, he halved its volume. When he tripled the pressure, the air’s volume was reduced to one-third. The change in volume of air when compressed was always Proportional to the change in pressure squeezing that air. He created a simple mathematical equation to describe this proportionality. Today we call it “Boyle’s Law”.

 

Fun Fact: No other concept has been more useful in understanding and using gasses to serve the needs of humankind.