# Ann Varela: Isaac Newton- Mathematician, Philosopher, and Optician?

An Interview with Ann Varela: Isaac Newton- Mathematician, Philosopher, and Optician?

Michael F. Shaughnessy –

1) Ann, the name Isaac Newton is perhaps well known in many spheres of influence, so it may be difficult to categorize this famous person- but in your mind- what were his greatest contributions?

This is a difficult question to answer because Isaac Newton has made so many contributions to mathematics and science. Obviously, his laws of motion have played a key role in the development and understanding of numerous other theories. His invention of the reflecting telescope in 1668 also ranks high on my list as does his experiments on the composition of light, beginning in 1665. His use of prisms showed how white light is composed of the colors of the rainbow. I see this experiment in action each afternoon when the setting sun shines through a west-facing window in my home, passes through a hanging chandelier, and results in numerous rainbows on the ceiling, as well as the east-facing living room wall. Who doesn’t like a rainbow?

2) Let’s start at the beginning, where was he born, and sadly, what happened to him in his early years?

One would think a birthdate is a straight forward question, but in the case of Sir Isaac Newton’s birthday, it depends on which calendar one uses. According to the Julian calendar, his birthday was December 25, 1642; however, the Gregorian calendar places his birth on January 4, 1643. Regardless of the date, the place was Woolsthorpe, Lincolnshire, England. Newton was born before his due date in a weakened state. He was not expected to live for even a day. Despite his grim prognosis, he lived for eighty-four years.

Newton’s father had been deceased for about three months before Newton was born. His mother remarried before Newton was two years old, but he was raised by his maternal grandmother. It is thought that this abandonment by his mother made him feel rejected by his family. Newton did not have much of a relationship with his mother until his step-father’s death in 1653. It is speculated that Newton’s traumatic youth was responsible for his psychotic inclinations in his later years. Newton even kept a diary of sorts confessing his desire to burn down his mother’s and step-father’s home, with them in it. Newton’s vehement defense of his life’s work is often associated with his anxiety during his youth.

3) Apparently, his family tried to make him a farmer- but with little success. What were his early years like?

When Newton’s step-father died, his mother had her mind set for her son, Isaac, to take on the responsibility of overseeing her property, which was a rural estate, including livestock and orchards. Taking care of cattle did not seem to interest Newton. There are accounts if Newton being found under a tree reading books, instead of tending to his duties on the estate.

Luckily, for Newton, his uncle saw to it that Newton was returned to The King’s School in Grantham, where he excelled at mechanics and technology and ultimately, completed his education. While at King’s School, he constructed windmills and a sundial which was precise to the minute. Not surprisingly, Newton was at the top of his class academically.

4) On to higher education–where did he start his university studies and what were his initial interests?

At age 19, Newton began his studies at Trinity College in Cambridge. Newton performed valet duties for faculty and well-to-do students for three years in exchange for tuition, until he was awarded a scholarship. The scholarship allowed Newton to continue his studies for four more years, whereupon he earned a master’s degree.

During Newton’s tenure at Trinity College, threat of the Great Plague (bubonic plague) emerged, so the college temporarily closed. More than 100,000 people were killed by bubonic plague in London. Infected rat fleas were the carriers of the dreaded *Yersinia pestis bacterium,* which were responsible for the plague.

Newton returned home and studied mathematics and physics under his own direction during the two year closure of the college. Apparently, Newton admitted that he first understood the theory of gravitation and optics during this sojourn. Newton was the first to discover that white light constitutes the colors of the rainbow. More specifically, he mapped out the spectrum by splitting white light through a prism. He also pressed on with his study of mathematics, including integral and differential calculus and infinite series.

Mathematics, chemistry, alchemy, and physics consumed Newton’s interest while in Cambridge. He was known to concentrate on a problem of interest unceasingly until he could fully comprehend everything about it. This personality trait made him a bit removed from the world around him though. This may be another reason why he never married; it seems he devoted his time and effort to his own academic interests and did not make time for a social life or put much effort into including outsiders into his personal life. He did, however, make time to meet with a few colleagues on occasion in the coffeehouses of London. Just imagine, more than 300 years ago, people were hanging out at a coffee joint discussing what interested them and today, similar conversations live on.

5) I suppose we will never know, but in terms of rumors, gravity, and the apple that fell on his head- how does this all fit together in terms of math?

I suppose it makes sense to think that Newton was hit on the head with an apple; after all, he did grow up on a vast acreage of farmland with abundant orchards. One account stated that his inspiration for the theory of gravitation came from watching the falling fruit. According to his colleague, William Stukeley, Newton frequently drank tea under the shade of apple trees while in an introspective state. One never knows when inspiration will “hit.”

So, what does falling fruit have to do with mathematics? Well, gravity is defined as the attraction of objects with mass or energy towards each other. This attraction presents itself as a force. Objects that are further away have a lower attraction, while objects of greater mass have a higher attraction. Newton devised a mathematical formula for describing such a force. See Figure 1.

Figure 1

_{http://thumbs.dreamstime.com/z/gravity-28972892.jpg}

6) Now, specifically math and calculus, what were his investigations and calculations?

Some of Newton’s mathematical discoveries include: the generalized binomial theorem, devising a method for finding the roots of mathematical functions, using mathematics to model the movement of fluids (*Newtonian fluid*), and the discovery of calculus. See Figure 2. It is important to note that Gottfried Wilhelm Leibniz is also credited with the invention of calculus. Apparently, Newton and Leibniz used different notations while describing their methods, making it difficult to see that they were actually describing the same concept. Their chosen terminology for naming their methods was also different. For example, Leibniz’s notation and “differential Method” was similar to Newton’s geometrical form of calculus. Scholars do believe the two mathematicians developed calculus autonomously. Although Leibniz published his ideas about calculus as early as 1684, Newton used his calculus concepts when he described fluxions in 1666 and again in 1687 in his *Principia* manuscript. Perhaps Newton should not have waited until 1693 to publish his calculus notation. Leibniz’s calculus notations are traced back to 1675. Some critics say that Leibniz saw some of Newton’s publications and stole his ideas and used different notations.

Figure 2

http://www.lightmypump.com/images/newtonian.jpg

7) Apparently he was mentored and had some great colleagues, some of which he admired, some of which he challenged, and some of which he fought with- What can you tell us in this area?

Newton’s closest colleagues included Robert Hooke, Edmund Halley, and Christopher Wren.

One of Newton’s better known disputes concerned his work on improving telescopes. Newton’s ideas were criticized by Hooke. This irritated Newton so much that he held feelings of animosity toward Hooke for the rest of his life and the stress of the situation apparently ignited a pattern of non-collegial behavior in Newton. The death of his mother and mercury poisoning are also considered life-changing events which might have played a role in his agitated behavior, although the mercury poisoning was not known about until after his death.

8) Supposedly, he vehemently defended his publications. Was this generally done at that time?

As you may have noticed, Newton had a big ego and did not like to be criticized. Even while he was appointed Warden and then Master of the Mint in London, Newton’s reign was considered to be dictatorial and domineering, and extremely controlling over the occupations and personal lives of younger students.

There could be a link between being a famous mathematician or scientist and having to defend your work. Newton was so gifted, that sometimes his own colleagues did not even understand some of the explanations and details of his work. Leibniz’s calculus manuscript was under fire and he was accused of plagiarism. Peter Mitchell’s work was also under scrutiny in the field of biochemistry. I’m sure that other disciplines have similar accounts of rivalries.

9) He apparently had one very major book- about “bodies in motion and three basic laws”

1) A stationary body will stay stationary unless an external force is applied to it;

2) Force is equal to mass times acceleration, and a change in motion is proportional to the force applied; and

3) For every action, there is an equal and opposite reaction.

These all seem somewhat self-evident today- but why were they so well received back in his time, and what is the relevance today?

Newton’s book, “*Principia*” was published in 1687; Halley funded this publication, by the way. It is widely thought to be the greatest scientific manuscript ever written. Within *Principia*, Newton tried to explain the motion of planets in simplistic terms. He felt there should be a mathematical rule to calculate the motion of the planets. Newton’s laws were accepted because they accounted for correlations. Newton’s laws had reference to the interconnectivity of the laws of motion; that is, his laws were differential. Although the German mathematician and astronomer Johannes Kepler already described laws of planetary motion, Kepler could not explain *why* the planets held in their orbits, only *how* they held their orbit. Newton’s differential laws explained *why*.

Newton’s laws have been a stepping stone for numerous developments made in modern-day theoretical physics. Newton’s laws not only helped to explain how outside forces influence falling objects, but also formed the course of all speculative research. Only the law of force had to be adapted, by Einstein, to the type of physical curiosities which were being measured. Newton’s law of motion made it possible to devise the kinetic theory of heat, recognize the laws of conservation of energy, and supplied a theory of gases confirmed in its smallest details, and deepened the understanding of the second law of thermodynamics.

10) His later years- where were they spent and how were they spent?

Near the end of his life, Newton resided in Cranbury Park with his niece and her husband. He died in his sleep in 1727. Mercury poisoning is thought to be the cause of death, as mercury was detected in his hair in the postmortem examination. He was known to experiment with mercury and even held it in his hands. Obviously, the poisonous nature of the element was not known at the time.

11) What have I neglected to ask?

Many of us have heard Newton called by another name, “Sir Isaac Newton”. He was knighted in 1705 by Queen Anne.