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March 05, 2019 Tuesday 01:33:51 PM IST

Sixteenth century was the century of Renaissance in the West, marked by the rise of science and technology. It required large-scale and persistent dissent to repudiate the mighty worldviews framed by Aristotle (384-322 BC) and Claudius Ptolemy (100-170 AD), which ruled the world for over two millennia.  That was not an easy task! In 1532, the polish astronomer Nicolaus Copernicus (1473 – 1543 AD) completed the first manuscript of his book, ‘De Revolutionibus Orbium Coelestium’ (‘On the Revolutions of the Heavenly Spheres’), sawing the seeds of a sun-centered (heliocentric) universe, opposing the Aristotelean concept of earth-centered (geocentric) universe. Later in history, this event is marked as the Copernican Revolution in science. The Danish astronomer Tycho Brahe and his German assistant Johannes Kepler challenged the theory of immutable universe proposed by Ptolemy. The formidable edifice of ancient Greek philosophy started developing cracks giving rise to the birth of modern science.  

It was 1583. A nineteen-year-old young man was attending prayers in the Cathedral of Pisa in Italy. His attention was suddenly drawn to how the oil lamps hung from the ceiling of the cathedral were lit. As the lamplighter knocked against them, Galileo noticed that the lamps started swinging to and fro. He tried to measure the time taken by each swing. Eureka! He got it! He found that irrespective of the extent of any swing, a given oil lamp took exactly the same time to complete one complete swing. As the displacements got larger, the lamps moved faster and as they were smaller, the lamps moved slower. And, in all cases, they took the same time to complete one swing motion. In other words, the period of the swing of the lamp was independent of the amplitudes at which they oscillated. All of them were isochronous! A sparkling moment in the life of Galileo Galilei (1564-1642), the prolific inventor and father of modern engineering!

Inadvertently, as it may appear, Galileo was inventing a fundamental principle of time-keeping. Pendulums are found to keep time in every oscillation, be it farther or nearer until they come to rest under the influence of frictional forces. Galileo proposed to attach the pendulum to the then existing clocks in an attempt to impart them with better efficiency in time-keeping. He imagined that he could refine all existing clocks, based on this principle of time-keeping inherent in all pendula. He started developing the so-called pendulum clocks.

It was in fact a long journey! Galileo continued his research to understand that the period of a swing radically depends on the length of the pendulum. As the length increased, the time taken for completing a to-and-fro motion also increased. After a large number of detailed experiments, Galileo proved that the period of the pendulum is directly proportional to the square root of length of the pendulum. He also estimated that the length of the pendulum with a period of one second should have a length of 99.314 cm (nearly 1 metre).  He also found that the period of the pendulum is inversely proportional to the square root of the acceleration due to gravity (g).

Armed with a host of such information, Galileo ventured into the making of a pendulum clock. However, it took further time to arrive at a satisfactory design for the same. He could arrive at a draft sketch only after several years of search and research. He was already advanced in age and had almost lost his eyesight. With the assistance of his son Vincenzio, he finally developed some final sketches for the pendulum clock. (See the figure). Every invention will have such a story of sheer perseverance to tell!

The basic design of the pendulum clock by Galileo was meant to feed the damped pendulum with regular dose of energy it expends to overcome the air-friction, so that it keeps oscillating. The energy to be supplied to the damped pendulum was stored in a coiled spring. Alternatively, it was stored as the potential energy of a descending weight. The major question of engineering was how to feed an oscillating pendulum with some energy at required intervals. The devise designed by Galileo allowed ‘escapement’ of energy from the storage medium to the pendulum at regular intervals. With this purpose in mind, Galileo connected a pair of pawls to the pendulum. As the pendulum swung, one pawl lifted clear of the pins allowing the wheel to rotate until ‘caught’ by the other pawl. As the pawl got caught, it imparted a small impulse to the pendulum, sufficient to keep it going at constant amplitudes. Thus the pawls regulated the release of energy from the storage to the pendulum. The pendulum, on the other hand, got ‘recharged’ on every swing!

The whole phenomena have similarity with a child on a swing. You push the swing as it has reached at the top of the arc, and give it a gentle helping push. If you push the swing irregularly, the sooth rhythm of the swing will be lost. As we come to the details of the engineering of a pendulum clock, it assumes important that the inertia and the friction between the moving parts in a clock is drastically reduced, such that a tiny dose of energy suffices to keep the pendulum going. Further, you are not supposed to perturb the pendulum greatly. In both these respects, Galileo’s pendulum clock required further refinements. The first reliable pendulum clock was invented by Christiaan Huygens nearly 15 years after Galileo’s death on 8th January, 1642. However, Galileo was rightly called the Father of Pendulum Clocks, ever since.

Let us note some characteristics of Galileo’s mind that helped him develop a pendulum clock. What was the characteristics of his personality that made him a fluent and creative mind? What aspects of his upbringing contributed to his entrepreneurial outlook? What attitudes supported his lifelong creativity?

Critical mind of an iconoclast

Galileo had a wonderful father in Vincenzo Galilei, who used to say: It appears to me that those who rely simply on the weight of authority to prove any assertion, without searching out the arguments to support it, act absurdly. Perhaps, Galileo inherited this critical mind from his father. He dared to challenge the formidable authority of Aristotle, who reigned the intellectual arena for over two millennia (2000 years!) with simple strokes of a critical genii.

For example, Aristotelian thinkers were of the view that heavier bodies fell faster than lighter ones, when released freely from a height. This meant that in the absence of air resistance (as in a vacuum), freely falling bodies would attain infinite acceleration and eventually infinite speeds! However, it was ridiculous to think about a body that would attain infinite speeds. Hence Aristotelians wished to repudiate the concept of a vacuum. They just rejected it saying: A vacuum does not exist. 

Now, it was up to Galileo to challenge such established concepts, which he did it with a bang! He dropped two differently sized cannonballs from the top of the Leaning Tower of Pisa. If Aristotelians were right, the larger (heavier) cannonball should have hit the ground prior to the smaller (lighter) one. Instead, both of them touched the ground almost simultaneously, proving the constancy of acceleration due to gravity acting on freely falling bodies. Galileo soon famed himself as a giant-killer, an iconoclast.

Galileo also predicted that if you drop a feather and a pebble, both would fall at the same rate in an evacuated tube! Though it sounds counter-intuitive, it was proven to be true again and again by different experiments. One of the curious experiments in this regard was done by David Scott, the astronaut of Apollo 15 Lunar Mission, who famously recreated this experiment on the surface of the moon in 1971 using a falcon feather and a hammer. Both of them hit the surface of the moon simultaneously!

With Galileo, was born the age of scientific method. As Stephen Hawking wrote: “Galileo, perhaps more than any other single person, was responsible for the birth of modern science.” (Stephen Hawking (2009). ‘A Brief History of Time: From Big Bang to Black Holes’, p.155, Random House).

Perceiving eyes of an eagle

It is not sufficient that humans have eyes; they must also see things as they are. To have eyes that perceive is something special. Galileo possessed such perceiving eyes. The lamps from the ceiling of the cathedrals were swinging from time immemorial. Billions of humans might have also watched it. But it took a Galileo to perceive the principles inherent in them.

Galileo not only observed the cathedral lamps swinging; he also dared to peep into the heart of the matter, just like an eagle. He continued to search and research for the reasons behind his path-breaking observations. And, eventually he could come out with a solution for time-keeping that enchanted the world. This is the strenuous path of an entrepreneur!

Ant-like persistence and perseverance

After capturing the principles of pendulum, Galileo went on to develop different types of time-keeping machines. He first visualized an instrument that would measure human pulse rate. He wanted to help physicians to notice the variations of pulse rates of their patients. Galileo named the instrument pulsilogia. Though not totally perfect, the physicians of his time found it a useful instrument.

Only later on, he ventured to develop a pendulum clock, which got prolonged to the fag-end of his life! His life was a saga of life-long creativity epitomized by sheer persistence.

Look at ants. They are just amazing creatures. They are found everywhere. We often meet them doing seemingly impossible tasks. In the face of difficulties, they never give up. On encountering an obstacle, they will make a way around it. They are giant-killers, though themselves are not like giants. They achieve their goals, rather bit by bit. Galileo possessed such ant-like persistence and perseverance.

Excellent adversity quotient

Galileo was a keen observer of the development of science elsewhere. He knew of an innovation, from the Netherlands, about an instrument that could magnify distant objects, just like a telescope. Galileo started working on this concept to further develop it into a telescope. With this new instrument, Galileo could see that the face of the moon is not that beautiful as described by the poets. It was rather cratered. On focusing his telescope towards Jupiter, he recognized that the planet actually had many moons. He discovered many new stars and even identified the spots on the sun.

Further observations using his telescope eventually led Galileo to the firm belief that Copernicus was right when he claimed that the earth was moving round the sun and not otherwise as blindly believed by many other scientists, who trusted in the authority of Aristotle in this regard. He postulated a sun-centered (heliocentric) world, as against the earth-centered (geocentric) world of Aristotle.

Galileo was accused of inaccuracies by his detractors. Resorting to the authority of the Catholic Church of the time, many of them pleaded Galileo (who was himself a dedicated Catholic) to be guilty of heresy or erroneous teaching. The well-known trial by the notorious Inquisition pronounced Galileo guilty of suggesting: 1) The sun is the center of the world, and that it does not move from east to west and 2) The earth does move, and is not the centre of the world.  

On accepting the judgment, Galileo is said to have quipped in Italian “Eppur si muove” [epˈpur si ˈmwɔːve], meaning “And yet it moves”! Words of a born-rebel, adorned with excellent levels of adversity quotient, the ability to withstand tough life situations with natural humour! Galileo was not prepared to subdue to the weight of any authority!

Armed with critical mind, perceiving eyes, ant-like persistence and perseverance, excellent adversity quotient, Galileo Galilei reigns supreme as the Father of Modern Science and Engineering!

Dr. Varghese Panthalookaran

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