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Brendan Jordan
Frankie Clifford
Miller
Physics
4 October 2010
Intro to the History of Physics
1. Origins of Physics
When most of us look to the nighttime sky we don’t see the paths of stars etched out in
mathematical formulas across the inky blackness of space. We see lights and colors. These
heavenly orbs are inspirational not because of the sheer complexity of the numbers behind
them, but the simple beauty, the core aesthetic in the most basic of human terms. Modern
physics has developed to the point of what is, for some, incomprehensible complexity. It is a
rare few who can see math while they watch a meteor draw its hot, white trail for an instant
across the sky. For most of us, however, a meteor is just a meteor.
Early humans in a pre-technological world would have, obviously, inhabited an
environment devoid of complex scientific calculations. For them, the motion of the heavens
was not only a great mysterysome confusing dance which could not be grasped by the
human imagination; it was, in fact, truly beyond explanation. Like non-physicists in the modern
day, early man’s questioning about the nature of the sky would have gone largely unanswered.
They might come to conclusions about the basics: that the sun rises in different places
depending on the day, and sets on the other side of the horizon. But beyond this, any answers
would come in the form of myth.
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It seems an unlikely place for the birth of what is today the core of all quantitative
physical sciences, but thousands of years ago, this primitive urge to ponder the great mysteries
of the surrounding world is ultimately the spark that eventually led to modern physics. Of
course, such inquiry was not restricted to the sky. People might have been just as curious as to
why a spear only moved so far, or why water would not fall upwards. The fundamental
component of all of these questions, though, is the simple fact that at the time, humans could
not arrive at the answers.
Physics was not born in its scientific, evidence-dependant form. It began with thought,
based on observations of the surrounding world. From there it took a logical next step. Once a
question was asked, the answer was sought after, and for the earliest civilizations, thinking
about something long enoughkeeping careful mental notesmight lead to that answer. With
the invention of written language, this progressed a step further, giving humans the capability
to record their observations. Out of this came the ability for one person to access the
knowledge of another, which led to a greater means of answering questions.
Early human societies, once able to work out problems collectively, began the long road to
application of their learned knowledge. In some of the earlier forms, these applications looked like
maps or calendars. The druids in ancient England constructed Stonehenge, quite possibly a giant
calendar which “allowed for more efficient and successful agriculture” (Wilson). Once the druids
understood that the sun moved through the sky dependant on the seasons, and that its location could
mark the passage of time, they could have constructed this enormous structure to track the sun’s
progress. This is just one example. In the earliest forms of physics, this pattern repeats time and time
again. People observe a pattern, understand it, and then use that understanding for practical
application. For millennia, however, this understanding was restricted to the basicswhat happens,
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when, where, and on occasion how. Until the rise of Greek civilization, however, there was never an
answer for why.
2. Aristotle and the Greeks
Ancient Greek science grew first and foremost out of Mesopotamian astronomy. Much of
Babylonian science was devoted to the prediction of heavenly motion, and “by the 4th century
B.C.E., they had developed a complex system of arithmetic progressions” (Brush) which could
predict the motions of the moon, sun, and various constellations with a fair degree of accuracy. This
first mathematical treatment of scientific observation embodied one of the earliest developments in
what is today a more recognizable physics.
From this mathematical knowledge, the Pythagoreans became some of the earliest Greeks to
theorize that scientific knowledge of celestial events can be completely described through
mathematics. Expanding on earlier mathematical models, the Pythagoreans used this principle to
create “the first physical model of the solar system” (Brush). While merely a single aspect of
physics, the act of modeling the solar system held tremendous implications for future developers of
modern physics, such as Kepler and Galileo.
As Greek science progressed, more and more aspects of modern physics began to take shape.
For instance, at one point, three different Greek philosophers (Leucippus, Democritus, and Epicurus)
formulated an atomic theory with regards to the nature of all matter in the physical world. This
theory was astonishingly similar to the modern understanding of the atomic universe. The basics of
their atomic theory state that matter in the physical universe consists of innumerable, particulate
bodies. They called these small particles “atoms”, from the Greek word for “indivisible”. The name
is largely because they viewed atoms (rather falsely) as being completely solid objects that could not
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be divided into smaller particles (Berryman). While today’s science has proved this wrong, it was a
step in the right direction. The other basic aspects of the theory, however, are even more striking.
These atoms, according to their theory (which in this sense is now supported by modern science) are
particles which move in a void, an empty space. All that the universe is, then, is in essence a void
occupied by tiny atoms which constitute our physical realm. This revolutionary idea came about as a
method to explain the nature of change (Berryman), and perhaps the most surprising detail is that
there was no way for the Greeks to confirm or even test this theoryit was purely a philosophical
argument. Unfortunately, though, this theory at the time was harshly criticized by Aristotle, and
eventually became a historical obscurity for centuries, until it was revisited much later in the modern
age (Brush).
Aristotle’s winning argument is by no means even close to the scientific accuracy of the early
atom theory when we view these two through a modern lens, however it is quite possible that no
single theory has ever done as much to shape the nature and future of physics than this philosopher’s
view on the nature of existence. Aristotle himself is one of the greatest figures in the history of
Greek science, and his primary theory which influenced the world of physics was his concept of
four, pure elements which combine and interact to create the physical world which we inhabit.
Essentially, this revolutionary theory (for its time) dictates that there are four basic elements
that exist in nature of which everything else is made. These are Fire, Air, Water, and Earth. While
today we might associate these words with their physical manifestations, in Aristotle’s view these
elements were pure, and different than the sorts of fire, air, water, and earth we experience on a day
to day basis. For example, the air we breathe is not just air, but a combination of fire and air (this is
likely due to the fact that the air in Aristotle’s realm was warm). In essence, Aristotle theorized that
all things are made of a combination of these elements, something which gives each object a natural
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place and physical existence in the universe. While today we understand the major flaws in this
theory, it did one thing that essentially sparked a great deal of all the physics that was to follow.
Aristotle’s theory of elements was, first and foremost, an effort at explaining change and
motion. His concern was not so much to determine the origins or roots of matter itself, but to explain
why matter changes, and why things move. In his mind, motion could be categorized in two ways:
violent motion, and natural motion (Bodnar). The idea of natural motion was the driving force
behind his elemental theory. What he postulated was that the four elements each have their unique
natural home in the universe, a place or level in which each exists compared to the rest. Earth
constituted the first layer, water above that, air above that, and finally a heavenly layer of fire. The
basics of natural motion, then, are that all things move because the elements of which they are
comprised “tend to seek their natural place in the order of things” (Fowler). Smoke for example, a
combination of fire and air, rises because the fire within it is seeking to reach its natural home, the
highest layer of elements. The air as well is above earth, and so smoke would naturally rise, given
that both its elements exist above our own worldly level.
Aristotle’s other theory, his thoughts of violent motion, are perhaps the most influential of all
his ideas, however. In his mind, motion must have a cause, and while an object is in motion, there
must be a force acting upon it at all times. This rule is remarkably similar to Newton’s law of inertia
centuries later, and certainly Aristotle’s original views on motion carried through medieval physics,
at least in some respect, to affect Newton’s ideas. The problem that Aristotle faced, though, with this
idea of a constant presence of force for a moving object, was that of violent motion. If a ball is
thrown, the original hand which supplied the motive force releases it, and according to this theory
the ball should immediately fall to the ground in that case (Franklin). This, however, is clearly not
how the world works. The way Aristotle explained this conundrum, then, was that an object in
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violent motion receives a sort of incorporeal force from the original motive object, and this force
affects the air around the object being moved. The result, then, is that the air (or in some cases fluid)
surrounding the moving object is stirred by this force, and offers some continual propulsion to carry
the moving object for a period through the air (fluid), even once the initial motive force is removed.
This theory of violent motion was later harshly criticized by medieval and renaissance
scholars, namely because it would fail to explain motion in a theoretical void (a place without air,
fluid, or any other sort of matter with which to carry an incorporeal force). While much of
Aristotle’s ideas, then, were later disproved or discredited, he did establish for the first time in
western society a science based firmly in natural, observable phenomenon. And while he did not on
his own create the idea of actual experimentation (for his theories arose solely out of contemplation),
his methods nonetheless provided a great step down the path toward modern physics.
3. Galileo and Islamic and Medieval Physics
Galileo’s most work with Physics was his ideas on Motion. He disproved the ideas of
Aristotle, who believed that heavier objects fall faster than lighter ones. Through series of
experiments he concluded that all objects, regardless of their density, fall at the same rate. In his
experiment, The Leaning Tower of Pisa, he proved this fact. He dropped two different objects of
different weight (one ten pound, one that was one pound) off of the Tower of Pisa, both landed at the
same time. Therefore, they both, because of gravity, had the same speed coming down to earth. He
wrote a book, De Motu, “On Motion” which was never published, that described his observations
and discoveries.
He developed his theory on Atomism, disapproving Aristotle’s first arguments on the matter.
He wrote that we perceive matter with two qualities, of touch, the primary qualities, and what we
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perceive, color and taste which are secondary qualities. These qualities are more various, because
they are opinions, therefore there are secondary, because in observations theses can be inconsistent
from different perspectives. He came to the conclusion in Discourses on Two New Sciences of 1638.
that objects are made up of infinite numbers of small particles, which are held together by an infinite
number of small vacua, proving that “Atomism” is mathematical. He is also known for his creation
of the telescope. Galileo also did work with the pendulum, and his discovery that the period of time
in which the pendulum swings back and forth does not depend on the arc of the swing.
Early Islamic science is most notable for its work with navigation and maps, and continuing
the ideas about Science that the Greeks and Romans originally worked on. They did not change the
fundamental ideas, but helped to strengthen them, and form them. They translated countless books,
and journals of Roman and Ancient Greek scientists, this information would be essential to Europe
during the Scientific Revolution, after they were translated into Arabic, the Christians translated
them into Latin. They also coined the idea about zero, which without zero, we never would have
progressed in math or science. Before them, there was no such thing as zero. They were also famous
for their development of Universities, where many new scientists flocked to study and discover.
Early Europe used the same idea, and created many universities, which was important to the
developments of science, and especially the Scientific Revolution. The world became much more
interested in Science, when the information and study became more accessible, and worthy.
Medieval scientist worked a lot on the idea of mechanics. John Philoponus worked on
Aristotle’s idea on projectile motion, that motion requires a continuing cause. Aristotle believed that
the surrounding medium was pushed by the original mover, and continued the energy of pushing the
projectile. However, if the medium were noticeably less strong than the projectile, it would be heard
to prove that the motion could be continued as such. Philoponus believed that the motion of the
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projectile was influenced by an incorporeal force that was impressed on it by the original mover, it
would finish its motion as soon as the impressive force wore off. This is the common term of
“impetus”, when the impetus is impressed against the projectile, it can have continued motion unless
it is interrupted or dissipated.
Copernicus was famous for his idea on how the earth rotated the sun, not the other way
around. Johannes Kepler worked on the idea that the planet travels around the sun in elliptical orbits.
He also disproved the idea of uniform circular motion of the planets and their spheres. He believed
that magnetic force holds the planets in orbit, and that a planet moves in a manner in which the sun
always sweeps out equal areas in equal times. He created the mathematical equation that “the square
of the period in which a planet orbits the sun is proportional to the cube of its mean distance from the
Sun”. These two ideas disapproved the previous Aristotelian physics, that the earth was the center,
and the idea of circular motion.
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Works Cited
"Aristotle." UCMP - University of California Museum of Paleontology. Web. 06 Oct. 2010.
<http://www.ucmp.berkeley.edu/history/aristotle.html>.
Berryman, Sylvia. "Democritus (Stanford Encyclopedia of Philosophy)." Stanford Encyclopedia of
Philosophy. Web. 06 Oct. 2010. <http://plato.stanford.edu/entries/democritus/>.
Bodnar, Istvan. "Aristotle's Natural Philosophy (Stanford Encyclopedia of Philosophy)." Stanford
Encyclopedia of Philosophy. Web. 06 Oct. 2010. <http://plato.stanford.edu/entries/aristotlenatphil/>.
Brush, Stephen G. "Physical Science :: Islamic and Medieval Science -- Britannica Online
Encyclopedia." Encyclopedia - Britannica Online Encyclopedia. Web. 06 Oct. 2010.
<http://www.britannica.com/EBchecked/topic/458717/physical-science/32541/Islamic-andmedieval-science>.
Fowler, Michael. "Aristotle." Galileo and Einstein Home Page. Web. 06 Oct. 2010.
<http://galileoandeinstein.physics.virginia.edu/lectures/aristot2.html>.
Hooker, Richard. "Greek Philosophy: Aristotle." Washington State University - Pullman,
Washington. 06 June 1999. Web. 06 Oct. 2010.
<http://wsu.edu/~dee/GREECE/ARIST.HTM>.
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02 June 2005. Web. 06 Oct. 2010.
<http://outreach.atnf.csiro.au/education/senior/cosmicengine/renaissanceastro.html>.
"Physics--Causes of Motion: Medieval Understandings." Jrank.org. Web.
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"Structure of the Universe." Hans J. Haubold. Web. 06 Oct. 2010.
<http://neutrino.aquaphoenix.com/un-esa/universe/universe-chapter3.html>.
Van Helden, Al. "Science | On Motion." The Galileo Project. 04 Aug. 2003. Web. 06 Oct. 2010.
<http://galileo.rice.edu/sci/theories/on_motion.html>.
Wilson, Hugh. "BBC - History - Stonehenge Dig 2008." BBC - Homepage. Web. 06 Oct. 2010.
<http://www.bbc.co.uk/history/programmes/stonehenge/article1.shtml>.