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Physics Before Galileo in the 13th Century

Leonard Kelley holds a bachelor's in physics with a minor in mathematics. He loves the academic world and strives to constantly explore it.

The biggest drive towards what we consider the scientific mindset was driven initially by religious ambitions. One who best exemplified this was Peter of Abano, who wanted to take the physical concepts that Aristotle had developed in antiquity and somehow marry them to the ideas in Catholicism, as driven by his Dominican Order. Abano commented on the collective works of Aristotle, not being shy to state when he disagreed with him because man was fallible and prone to making mistakes in his search for the truth (yet he himself was exempt from this). Abano also expanded on some of Aristotle's work, including noting how black objects heat up easier than whiter ones, discussed thermal properties of the sound and noted how sound was a spherical wave emitted from a source. He was the first to theorize how light waves cause rainbows via diffraction, something that would be explored more in the following century (Freely 107-9).

Other areas that Abano covered included kinematics and dynamics. Abano subscribed to the idea of impetus as the driving force behind all things, but its source always being external rather than internal.Objects fell at a faster rate because they were trying to get to their nautral state, according to him. He also discussed astronomy, feeling that the phases of the moon was a property of it and not a result of Earth's shadow. And as for comets, they were stars trapped in Earth's atmosphere (110).

One of Abano's students was Thomas Aquinas, who carried on the work of his predecessor with Aristotle. He published his results in Summa Theologica. In it, he talked about the differences between metaphysical hypotheses (what must be true) and mathematical hypotheses (what corresponds with observations of reality). It boiled down to what possibilities existed for a situation, with only one option belonging to metaphysics and multiple paths belonging to mathematics. In another book of his entitled Faith, Reasoning, and Theology, he delved deeper into the comparisons between science and religion by discussing the realms of exploration both offered (114-5).

Thomas Aquinas

Thomas Aquinas

One important aspect of science is its ability to stand up to repeated testing of the experiment to see if the conclusion is valid. Albertus Magnus (also a student of Abano) was one of the first to do so. In the 13th century, he developed the notion of repetition of experimentation for scientific accuracy and better results. He also was not too big on believing something just because someone in authority claimed it to be so. One must always test to see if something is true, he contended. His main body of work though was outside of physics (plants, morphology, ecology, entryology, and such) but his concept of the scientific process has proven to be of immense value to physics and would lay the corner stone for Galileo’s formal approach to science (Wallace 31).

Another forefather of the modern scientific frame of mind was Robert Grosseteste, who did a lot of work with light. He described how light was at the beginning of everything (per The Bible) and that this motion outward dragged matter with it and continues to do so, implying that light is the source of all motion. He talked about the progression of light as a set of pulses, extended the concept to sound waves, and how one action determines another and so can stack up and go on forever...a paradox of sorts. A big area of exploration he led was on lenses, at the time a relative unknown topic. He even had some precursor work in the development of a microscope and a telescope, almost 400 years before their formal invention! Now this is not saying that he got everything right, especially his ides on refraction which involved bisectors of different rays with relation to the normal line to the surface of the refractor. Another idea of his was that the colors of the rainbow are determined by the purity of the material, the brightness of the light, and the quantity of the light at the given moment (Freely 126-9).

One of Maricourt's illustrations.

One of Maricourt's illustrations.

Petrus Peregrinus de Maricourt was one of the first to explore magnets and wrote about his discoveries in Epistola de magnete in 1269, following scientific procedures his predecessors like Grosseteste did by taking care in order to reduce systematic errors. He talks about many magnetic properties including their north and south poles (attraction and repulsion) and how to distinguish between the two. He even goes into the attractive/repulsive nature of the poles and the role that iron plays in all of this. But the coolest bit was his exploration of breaking up magnets into smaller components. There he found that the new piece wasn’t just a monopole (where it’s just north or south) but in fact acts like a minute version of its parent magnet. Petrus attribute this to a cosmic force permeating in magnets arising from the celestial sphere. He even hints at a perpetual motion using the alternating poles of magnets to spin a wheel – essentially, an electric motor of today (Wallace 32, IET, Freely 139-143)!

In a step towards data analysis, Arnold of Villanova (a student of medicine) hinted at the exploration of trends within data. He tried to show that there was a direct proportion between the sensed benefits of medicine to the quality of the medicine given (Wallace 32).

Jordanus Nemorarius and members of his school explored statics as they looked into the lever that Aristotle and Archimedes had developed in order to see if they could understand the deeper mechanics. Looking at the lever and the concept of the center of gravity, the team developed “positional gravity” with parts of a force (hinting at the eventual development of vectors by Newton’s era) being distributed. They also used virtual distance (really an indivisible-like small distance) as well as virtual work to help develop a proof for the lever law, the first to ever do so. This led to the axiom of Jordanus: "motive power that can lift a given weight a certain height can lift a weight k times heavier to 1/k times that prior height, where k is any number." He also extended the lever law ideas to a system of weights and pulleys on different inclines (Wallace 32, Freely 143-6).

Gerard of Brussels in his De motu tried to show a way to relate “curvilinear velocities of lines, surfaces, and solids to the uniform rectilinear velocities of a moving point.” While that is a bit wordy, it foreshadows the mean-speed theorem, which shows how different “rotational motion of a circle’s radius can be related with a uniform translational motion of its midpoint.” Which is also wordy (Wallace 32-3).

As we moved into the 14th century, the methodology grew more complex, and one of the precursors to calculus was born. But that is for another article....

Works Cited

Freely, John. Before Galileo. Overlook Duckworth, New York. 2012. Print. 107-10, 114-5, 126-9, 139-146.

IET. “Archive Biographies: Pierre de Maricourt.” Theiet.org. Institute of Engineering and Technology, Web. 12 Sept. 2017.

Wallace, William A. Prelude to Galileo. E. Reidel Publishing Co., Netherlands: 1981. Print. 31-3.

© 2021 Leonard Kelley

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