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How Isaac Newton changed Physics

Abstract

Isaac Newton is acknowledged as one of the greatest scientists of all time. But what precisely is it that lies behind such greatness as to make us consider these heroes as almost superhuman as if they were born with physical and intellectual privileges, kissed by the skies, and predestined for grandeur?

Actually, there’s nothing that special. No incredible luck, no predestination. Allow me to tell you why.

Sadly, behind such courageous and determined people, there is often a painful background, studded with many difficulties. Difficult lives, family dramas, wars, or an environment that was unwilling to stimulate and appreciate the talents of someone with a tendency to think outside the box.

In order to understand what lies behind Isaac’s qualities and how we are connected to him, we will not discuss his biography – something that was done thoroughly and in great detail in many books – but we will talk about Isaac’s human side, trying to understand which were the mechanisms that led this young boy who grew up in an English village with an illiterate family, into becoming a member of the Royal Society and being remembered as one of the greatest scientists of all time, despite being considered the fool of the class at school.

Isaac was born in a difficult historical period, such as the one in which Anglicans and Puritans were fighting each other, and for this reason, many men fell, leaving their children fatherless. The same happened to young Isaac, too.

He was born frail, and immediately orphan of a father who died when his mother Hanna was six months pregnant, during a battle he fought for Charles I against the MPs. He came into our world on a Christmas day, in the sadness of a loss he could not yet realize, in a village where people felt undecided on whether to believe that any fatherless newborn children would be born with supernatural powers, or doomed to die within their first month alive.
Isaac managed to survive, but he was soon abandoned by his mother, who made the forced choice of remarrying a much older man, in order to guarantee herself and her son an inheritance and some financial well-being.
In order to do this, he left his son in the care of his grandmother, who soon sent him to study with friends of the family. It was with them that Isaac began his new life as an apathetic student, marginalized by his fellow classmates and deemed as impatient and unintelligent by his teachers. From then on, he would feel different, alien, and excluded for the rest of his life.

There are many of us who, at some point in our lives, have felt at least once different, misunderstood, and sometimes not accepted by our peers. We may have been deemed as strange, out of touch with reality, perhaps rejected, treated pitifully, or simply ignored. All of us, at least once in our lives, have had to face the weight of our own passions, feeling belittled or judged for making a wrong choice for our aspirations, such as preferring art to a path of studying which would have granted us a safe place in society.
Isaac suffered the same anathema.
Considered strange due to his curiosity towards nature, a place where the boy loved to immerse himself in order to escape from the misfortunes of his life, Isaac began to isolate himself from others around the age of thirteen. He took comfort in his own world of thoughts and fantasies.

He was not very attentive at school, he usually lurked at the back desks, did not listen to lessons, and did not commit at all. His teachers considered him to be an inadequate and intolerant boy. Friends simply called him “stupid”. He loved to build small objects, which he then gave to his female peers, receiving harsh judgments from other boys for this. Precisely because of these attitudes, he was even targeted by a bully, among other things the son of the man who housed him. He was forced to fight him, and by a stroke of luck, he managed to subdue his opponent.

From that moment, Isaac began to feel a growing desire for retaliation and revenge. Realizing that the path of violence would not lead him far, he became convinced that he had to beat them on another level. He then began to study a way to ingratiate himself with the teachers and achieve an important role in his class, so that his classmates no longer had elements to discredit him.
The pre-adolescent Isaac Newton began to approach studies with passion, driven by a sense of revenge towards his companions, and not only: he did do it to face his three greatest enemies: the sense of inadequacy, inferiority, and loneliness.

Things gradually changed, but Isaac was never able to genuinely enjoy his position at the top of the class. Rather, he continued to isolate himself more and more, as he was afflicted by a very strong social anxiety.

His curiosity led him to ask unusual questions for a boy or a man not familiar with philosophy, and this convinced him that there was no place for him in that world. That he was doomed to loneliness and feeling marginalized.

One day in his home library, Isaac found answers to some of his questions: Why do objects fall? Why do spinning kids have their heads tilted back?
Why does the rainbow always have the same colors? But above all, he realized he was not alone in the world, that he wasn’t the only one having thoughts and curiosities which his companions considered to be quite bizarre.
Isaac found a family of his own in philosophers, thinkers, and scientists, in people similar to him, finally finding his place and his passion: natural philosophy, philosophical thinking applied to the study of nature, a very close sister of physics, which is the study of nature itself.

Thanks to these figures his sadness lessened, but not his social anxiety.
Once he discovered his passion, Isaac became practically unstoppable: he always gave it all in the study and application of the arts he loved so much and soon achieved the recognition he desired, as well as the love of teachers and family friends alike, who now considered him to be the pride of his village. Unfortunately, with his inability to overcome his anxiety, Isaac would soon fall into the trap of his loneliness. He usually felt alone, misunderstood, attacked, and hated by those he would have liked to have close.

Isaac’s life was not a simple one at all: despite his academic achievements, he was denied to study by his mother when she returned after the death of her second husband, accompanied by several siblings whom Isaac would have considered strangers.
The difficult relationship with his mother was a heavy burden for Isaac, who always failed to feel part of a family even as an adult, and ultimately returned to isolate himself in his thoughts, taking shelter in his inner world. However, Isaac’s mother would soon understand her son’s inadequacy in managing their estate, so she sent him back where he came from, back to his studies, much to Isaac’s delight.

Isaac’s mother was so kind to her son as to deny him even the bare minimum financial support he needed, reducing him to a state of poverty. In order to study, Isaac worked in the service of his own luckier peers, cleaning chamber pots and styling the hair of fellow students who were definitely not intellectually superior to him. The boy’s anger allowed him to continue his studies, but without achieving great results. Luckily for him, the university understood the boy’s unease and offered him a scholarship for completing the course.

Even though the war was over and England had decided to return to the monarchy with Charles II, the times that followed were not easy. The arrival of a pandemic forced Isaac to leave the College again and reunite with his hated mother.
During this pandemic, Isaac closed himself to his studies by excluding himself from forced family life, reaching his most important scientific results.

Thanks to the scientific results he achieved, Isaac was invited to join the Royal Society: at first glance we could say that Isaac could finally live in an environment favorable to him, surrounded by fellow scientists. It was not like that at all.

It is not unusual that the scientific academic world tends to be particularly hostile to speculation and rigid towards new ideas which are not adequately substantiated. Isaac saw in the Royal Society a veritable academic jungle, and in the figure of Hooke, the fiercest of predators. That young boy had entered the Royal Society talking about the splitting of a light beam, and he was rather excited by his discovery.
He understood that the white light beam was not pure – as other scientists intended – but rather the union of all colored beams, which on the contrary were pure and immutable. It so happened that years earlier Hooke had published a book that explained – and intended to prove – the exact opposite, and this put young Isaac in the jaws of a predator, who would then induce him into leaving the Royal Society shortly after and avoid talking about any of his researches or discoveries, almost for his entire life.
Social anxiety, discouragement, and a sense of exclusion had won once again.

2,300 years ago, in ancient Greece, Plato and then Aristotle intended to investigate the divine, define it, describe it and then discuss its implications for the earthly world.
Plato wanted to understand the scientific origin of the gods and advised to use astronomy, which was still in its infancy at the time.

For the first time, human beings were daring to try and understand divine behavior (that of celestial bodies), starting a scientific revolution that would reach its climax with Isaac Newton. For the first time, science and religion cooperated, and this would have been a very happy and profitable marriage for both spouses, although the divorce will not be one of the best.

Let’s go in order. Plato and then Aristotle go on to describe the behavior of the celestial world.

The sun and the stars revolve around the earth in a perfect and eternal way. The moon shares this behavior.
The celestial world, located beyond the moon, is an immutable, eternal, and perfect world. It was extremely regular: they would have called it the cosmos, which in Greek means “ordered”.

However, there were five planets (Planet means wanderer, in Greek) that which not follow circular movements and had a disconcerting behavior. Through some forcing and an imaginary ethereal wind that pushed planets, they too were eventually shown in a perspective of celestial perfection.

The celestial world was composed of ether, an incorruptible and eternal element, while the terrestrial one was composed of four elements: fire, air, earth, and water, which were corruptible and explained the behavior of terrestrial things. Everything was contained and moved by spheres, which were all enclosed by the outermost sphere, the Primum Mobile, the primary mover or God.

This meant that the celestial world was immutable and perfect, while the terrestrial one was changeable and corruptible. However, when asked to explain the behavior of comets, Aristotle said that they were not astral or perfect, but terrestrial exhalations that caught fire at high altitudes. He had placed them between the earth and the moon.

Now that science had provided a flattering explanation of the divine, religions began to use it in order to assert themselves. In particular, St. Thomas Aquinas reconciled Christianity with Aristotle’s geocentric universe. God could only be the primum mobile and the planets, stripped of their role as demigods, would have moved on spheres drawn by Angels.

But following the worst European plagues and epidemics, it happened that the church lost many of its most valuable men, and for this reason, those vacancies were filled by men with less virtuous intentions. This unleashed a series of shameful scandals that put the unity of the church to the test. Martin Luther and Copernicus would have pointed the finger at Catholicism: Protestants were born and divine geocentrism was questioned. The church responded harshly, as in 1572, a new star appeared in the sky (despite the sky having to be incorruptible, eternal, and perfect), and five years later a comet reappeared which through parallax was measured to be farther than the moon (another imperfect element was living in the celestial world?!).
The answer to all this was inquisition against the heretics: Giordano Bruno was burned alive, and many scientists began to prefer their own security to the dissemination of their ideas, although they were genuinely interested in reconciling the new Copernican science with the divine.

Kepler (a Copernican and Lutheran, so he was basically public enemy number one) was an astronomer who managed to discover three interesting things about wandering planets.

– The square of a planetary year is a multiple of the planet’s cube distance from the sun, and this applies to all planets. More distant planets have long years, while closer ones have short years.

– Planets did not have a constant speed, but they accelerated and slowed down.

– Orbits were not circles, but ellipses.

Furthermore, Kepler sensed that the planets were being attracted to the sun, almost by some kind of magnetic force. Heavenly perfection was seriously endangered.
Galilei built a rudimentary telescope and observed the Moon and its imperfections (the craters). Due to this, he was found guilty by a court of cardinals and forced to deny those discoveries, retracting them.

The Holy Church’s reaction pushed science away and led to a sharp and painful separation: that special bond would never be mended again. The dispute would never die out, and God would be banned from scientific discourse in the future.

The death of the celestial kingdom coincides with the death of Isaac’s mother, who had returned to Woolsthorpe to watch over her. In those moments of delicacy and emotion, the young man regretted many of his choices and cursed his stubbornness.
During one of these melancholic evenings, Isaac was deeply immersed in his thoughts as he was spending time in his garden when he realized he had a beautiful moon in front of his eyes. The same one he had seen fourteen years earlier and that had prompted him to ask himself many questions about celestial bodies and centrifugal force.

His doubts were these: why does an apple placed on a very tall tree fall to the ground, despite the moon not doing the same? The moon doesn’t fall due to centrifugal force, which opposes the gravitational force exerted by the earth.

Isaac imagined being a child with a rope tied around his torso. The other end of the rope would be tied to a pole or a tree. Running forward, this child would have made a circular journey, thanks to the tensioned rope. This rope is the gravitational force, the child is the moon and the pole is the earth.
Not enough, the moon is in perpetual and rectilinear motion, which becomes circular once again thanks to the centripetal force. As we already said, the centripetal force exerted by the rope attracts the child towards the pole, but its rectilinear motion cancels this effect: in the end, it is only the direction that changes, moment by moment.

But what if there was an elephant in place of the baby?
The tree, or the pole, would have been uprooted: so it all depends on the mass of the two elements involved. An elephant could not uproot a tower, but he would with a pole or a tree still young and thin: it’s almost like child’s play.
Certainly, the rope had a role: length seemed to matter. Earlier on, Kepler had discovered that a planet revolves around the sun thanks to a centripetal force.
Not only that, he had discovered that a planetary year squared was worth the cube of its distance multiplied by a constant. Isaac quickly realized that all these things were connected.

Isaac translated his thought into mathematics: a person of mass m attached to a pole with a rope of length d completes one complete revolution in time T.

Equation Box

This is how Isaac Newton went from the rough idea of Eq.1 to his final equation, basically using Kepler’s definition of the Yearly Period of a planet around the sun, and then generalizing it to all kinds of masses. To properly understand Hint 1, read about Vectors. Please keep in mind that Hints 1 and 2 are not about physics, but Linear Algebra.

(Eq.1)$\overrightarrow{F}= \frac{k_{1}m\overrightarrow{d}}{T^{2}}$

But Kepler had found that for planets:
(Eq.2) $T^{2}= k_{2}d^{3}$

Merging them together (a constitution of T in the first equation) Isaac Newton found this new equation:

(Eq.3)$\overrightarrow{F}= \frac{ k_{1}m\overrightarrow{d}}{ k_{2}d^{3}}$

We should remember that
(Hint 1)$\overrightarrow{d} = ||d||\widehat{d}$
so we can divide the magnitude/intensity of the vector from its directional part, that would take us to our equation.

(Hint 2)$\frac{\overrightarrow{d}}{d^{3}} = \frac{\widehat{d}}{d^{2}}$
and $\frac{k_{1}}{k_{2}} = k_{3} = k$

We can now compose the equation by merging the elements in Eq.3 to get a premature form of Gravitational Equation (as you will see, we only have one mass m):

(Eq.4)$\overrightarrow{F}= \frac{km}{d^{2}}\widehat{d}$

Isaac quickly understood that something was missing: an object falls perpendicularly to the earth, which is spherical. Considering two masses as points, and not thinking about their size, the idea of Gravitational attraction quickly took the scientist to imagine a reciprocal force. That made a lot of sense if we analyze it on a small scale. So now the mass m becomes:
$m =m_{1} m_{2}$

and k = G, it’s value is constant and equals to:

$G \approx 6.67428 \times 10^{-11} m^{3} kg^{-1} s^{-2}$

What we need to understand and appreciate about Isaac Newton is the fact that in the end, he is not at all different from any of us. He was not blessed with luck, nor was he considered a child prodigy or a role model for the family.

Far from it.

Isaac was bullied by his friends, pushed aside by his mother, he never had a real example to follow in terms of a motherly or fatherly figure. He was lonely, oppressed by his fervent curiosity, debilitated by social anxiety, and disarmed by the terror of the pandemic.

It is in human nature (and it also happens with many animals) to judge what is different, fear it, shy away from it or fight it. We all underwent the effects of this evolutionary “injustice”, perhaps even once in our lives.

Despite concepts such as those of gratitude, sharing and collaborations proving to be great evolutionary adaptations for the survival of our species and solidly backing the roots of our own society, everything that falls out of the scope of our habits is instinctively considered as potentially dangerous. All these scientists, artists, thinkers but also innovative, curious or extremely sensible or empathetic persons are well aware of that.

Isaac Newton is an example to follow, as he shows us that however difficult life is and no matter how many misfortunes seem to be magnetically attracted to us, if we’re driven by the right amount of desire for redemption and armed with plenty of patience, not only will we get what we want, but also make an important contribution to the entire world community.

It’s a given that Isaac did not discover the theory of universal gravity only to make his mother happy or for helping the English community, really. He did it for himself and for love of knowledge, in the same way that an artist doesn’t create for receiving applause or for selling his work, but only for the love and sake of art and for the joy of the process.

If we keep on moving nonchalant of any adversities, we too could be Isaac Newton.

Bibliography

Five Equations That Changed the World – Michael Guillen | Amazon Link
Never at Rest – Richard S. Westfall | Amazon Link
On the Heavens – Aristotle | Amazon Link