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<TITLE>Reading Revolutions -- Newton -- Intellectual History</TITLE>
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    <font face="Verdana,Arial,Helvetica" size="-1"><b><a href="lectures.html">INDEX</a></b><br><br><font size="+1"><center><i>Reading Revolutions:  Intellectual History</i><br><br>
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	Newton:&nbsp; Planets, Apples, and Scientific Revolution<br><br>
	<font size="+0">Theo Kalikow</font></font></font><p>&nbsp;</p>
	
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			<p align="left"><font face="Verdana,Arial,Helvetica" size="-1">The scientific progress from Ptolemy's geocentric 
			universe to Newton's mathematical definition of the elliptical 
			orbits of the planets produced multiple revolutions, but none so 
			far-reaching as that of Newton's physics. </td>
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			<p align="left">&nbsp;</td>
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			Newton shown behind an armillary sphere with Earth at the 
			center.&nbsp; Click to enlarge.

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&nbsp;<p><font face="Verdana,Arial,Helvetica" size="-1">
The following is a summary of Dr. Kalikow's presentation:</font></p>
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	<p>I<font size="+0"><font face="Verdana,Arial,Helvetica" size="-1">
	heard on the radio yesterday that it was the 100th anniversary of e=mc<sup>2
	</sup> but it was also the 318<sup>th</sup> birthday of <b>m</b>!&nbsp; 
	Newton, is of course, the person who made mass a scientific and lawful 
	concept.&nbsp; But before we get into that we have to look at the history of 
	the problem.</p>
	
	<p>Even before there was a written record there was an oral tradition of 
	astronomy.&nbsp; In caves we find marks indicating that people followed the 
	phases of the moon, kept track of stellar objects and paid attention to the 
	sky above them.&nbsp; All over the world, each civilization carried out 
	traditions of astronomy whether for agriculture or travel.&nbsp; What is 
	common to all of these traditions is the assumption that the earth is the 
	center of the universe.&nbsp; If you get outside and look at the sky, that 
	is what it looks like.&nbsp; This is called the two-sphere universe -- the 
	earth in the center and a second sphere rotating around it.&nbsp; Very early 
	in history, people realized that the earth was a sphere, not flat.&nbsp; A 
	librarian, Eratosthenes, actually measured the circumference of the earth in 
	the third century BC.<img border="0" src="pictures/Newton/1619w.jpg" width="336" height="350" align="right"></p>
	<p>Around 300 BC, Aristotle codified all of the traditions into a single 
	system.&nbsp; The earth was the center and all bodies would fall toward it.&nbsp; 
	The heavens were perfect and motion in the heavens would be perfectly 
	circular.&nbsp; If there were no planets we might still be there.&nbsp; The 
	planets move in peculiar ways given the Aristotelian method.&nbsp; Ptolemy 
	in 150 AD collected all the observations he could find and made ingenious 
	mathematical models to explain the planetary motions.&nbsp; (<a href="Galileo.html">Chris 
	Magri </a>went into this in some detail).</p>
	<p>This was the situation up until 1543 when Copernicus proposed the 
	heliocentric system.&nbsp; There was no physics to support it but Copernicus 
	solved the problem of the planets with a sun centered universe.&nbsp; If 
	Earth is a planet going around the sun, how do you explain the motions on 
	earth and the motions in the heavens?&nbsp; Tycho Brahe attempted to solve 
	the problem and refine the data by making more exact observations.&nbsp; He 
	used very very large instruments to increase the degree of accuracy of 
	positional measurements.&nbsp; If you have a measuring stick on the side of 
	a building rather than a small ruler, you are going to be able to measure a 
	degree of arc much more accurately.&nbsp; Kepler studied Brahe's data to 
	create a system that would fit the data.&nbsp; Kepler tried to make circles 
	work but they were only accurate to 8 minutes to degree of arc and Brahe's 
	data was accurate to 4 minutes to degree of arc.&nbsp; After many years of 
	work Kepler found that the only thing that would work was elliptical orbits 
	for the planets going around the sun at the center.&nbsp; There still was no 
	physics to back it up, still no understanding of why it should work.</p>
	<p>Galileo (1564-1642) was the first to have a new astronomical instrument -- 
	the telescope.&nbsp; He used it to look at all sorts of things.&nbsp; He 
	pointed it at the moon and was actually able to see that it had mountains on 
	it and was able to measure their height by the shadows they cast.&nbsp; He 
	saw&nbsp; the phases of Venus and the moons of Jupiter.&nbsp; The moons of 
	Jupiter provide a model of how the solar system could work.&nbsp; Galileo 
	had the first new data and method of seeing the universe.&nbsp; He didn't 
	like the ellipses of Kepler, preferring circles.&nbsp; He still didn't have 
	the physics to explain the motion of the planets.&nbsp; If the sun is the 
	center of the solar system and the earth revolves around it, why don't 
	things fall off the earth?&nbsp; That's how things stood until the time of 
	Newton.&nbsp; </p>
	<p>During the 16<sup>th</sup> century, the locus of scientific and political 
	power had shifted from the south of Europe to the north primarily due to the 
	building of ships for trade and defense.&nbsp; As this shifted the economy 
	toward import/export and urbanization, it was recognized that the economy 
	would do better if they knew more about navigation, natural phenomena, and 
	of course astronomy.&nbsp; In 1660 a group of scientists including Wren, 
	Boyle, Hooke, and Moray who had been meeting to discuss scientific matters 
	established the Royal Society.&nbsp; People in other countries were also 
	working on similar issues -- Descartes, Spinoza, Leibnitz -- and carried on 
	lively correspondence throughout Europe.&nbsp; </p>
	<p>In 1684 Halley goes to Newton to ask him about a question circulating at 
	the time.&nbsp; If a force falls off as a square of the distance what shape 
	would the orbit take?&nbsp; Newton said ellipse.&nbsp; How do you know?&nbsp; 
	Newton said that he had proved it previously.&nbsp; Halley wants to see the 
	proof and nags Newton until he finally sent it to him.&nbsp; Halley takes it 
	to </p>
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				<p align="center"><font size="2">A page from t</font><font size="2" face="Verdana,Arial,Helvetica">he
				<i>Principia</i> in Latin</font></td>
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	<p>the Royal Society and continued to nag Newton to write out his major 
	theories.&nbsp; Finally, in 1687 the <i>Principia</i> (full title<i> -- 
	Philosophiae Naturalis Principia Mathematica</i>) was published in Latin 
	with the formal proofs of Newton's physics. </p>
	<p>Newton was born the same year that Galileo died, 1642.&nbsp; He didn't 
	show any signs of genius at an early age.&nbsp; He graduated from Cambridge 
	and would have stayed on but 1665-1666 was a plague year and the 
	universities closed.&nbsp; Newton stayed home for two years and thought 
	about things.&nbsp; This appears to be the time that he created much of his 
	later work.&nbsp; He didn't write much and didn't publish anything.&nbsp; He 
	returned to Cambridge and two years later became the Lucasian Professor of 
	Mathematics at age 26.&nbsp; His most famous early work is a paper on optics
	in which he showed that light was made up of waves.</p>
	<p>
	<img border="0" src="pictures/Newton/1621w.jpg" width="450" height="338" align="left" hspace="5" vspace="7">He 
	did a very simple experiment to prove it.&nbsp; He passed light through a 
	prism to produce a rainbow of colors.&nbsp; This had been seen often enough, 
	but he got a second prism and was able to show that by passing the rainbow 
	of light through it he could rejoin the different colors to produce the 
	original white light.&nbsp; In 1671 he published his paper on optics and 
	light.&nbsp; 
	It was his first scientific publication and it was the first scientific 
	paper on the physics of colors.</p>
	<p>In the meantime, Newton continued to lecture on mathematics and began to 
	get quite a reputation.&nbsp; His correspondence increased.&nbsp; But he 
	found that when he wrote to other scientists they would write back and often 
	wouldn't agree with him.&nbsp; He didn't like that.&nbsp; He tended to stay 
	in Cambridge and avoid active contact with others.&nbsp; Thus, Halley had to 
	come to him.&nbsp; History justifiably gives Halley great credit for the the
	<i>Principia</i>.&nbsp; He not only nagged Newton but edited and bore the 
	cost of publication himself.</p>
	<p>The <i>Principia</i> described the entire physical world using a single 
	set of laws.&nbsp; The book is set up like a geometry with propositions, 
	proofs and diagrams.&nbsp; It looks like geometry, but in fact all through 
	the book Newton is using the calculus.&nbsp; The fundamental concept is the 
	concept of limits.&nbsp; What happens when a fundamental quantity, ratio or 
	proportion moves toward a vanishing point or starts at nothing and 
	increases.&nbsp; That's the underlying mathematical thinking underlying the
	<i>Principia</i> and of course, Newton invented it.</p>
	<p>Newton invented what he called mathematical philosophy but what we call 
	mathematical physics.&nbsp; He used observation but relied on mathematics to 
	refine his physics.&nbsp; This is the first comprehensive use of what we 
	call the scientific method:&nbsp; creating hypotheses, doing experiments, 
	refining the hypothesis and going back to make it into a theory.</p>
	<p>The end product was not a collection of disjointed laws that applied to 
	specific problems, but a cohesive set of laws within the theory that applied 
	to all matter.&nbsp; These laws can be used to derive the predictions for 
	all matter.&nbsp; For instance, he described the law of inertia:&nbsp; a 
	body at rest tends to remain at rest, a body in uniform motion in a straight 
	line will go on forever.&nbsp; It is indifferent which state of motion is 
	true.&nbsp; Those are the only two natural states of motion.&nbsp; The 
	circles of Copernicus are excluded from the natural state.</p>
	<p>Newton also invented the concept of mass.&nbsp; The quantity of matter 
	that adheres in a body is important, its weight will vary depending on 
	conditions, but its mass will remain the same.&nbsp; Another law from 
	Newton is universal gravitation.&nbsp; Between any two bodies in the 
	universe there is a force of attraction which is mutual, and is directly 
	proportional to the product of the two masses and inversely proportional to 
	the square of the distance between the two bodies.</p></font>
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	<p>With these tools and a few others Newton could explain the planetary 
	orbits, the behavior of falling bodies near the earth and the tides.&nbsp; 
	The laws apply to everything, including apples.&nbsp; Basically what Newton 
	said is that the apple falls from the tree because it and the earth are 
	attracted to each other and the earth is a lot bigger.&nbsp; The apple is 
	just like the moon.&nbsp; It and the earth are also attracted to one 
	another, so why doesn't it fall?&nbsp; Newton says because it is affected by 
	another law, the law of inertia.
	<img border="0" src="pictures/Newton/1584w.jpg" width="454" height="450" align="left"></p>
	<p>The moon is trying to fall toward the earth and it is also trying to fall 
	into outer space.&nbsp; At every point on the orbit, both laws are at work.&nbsp; 
	The result is that the moon is trapped into an orbit.&nbsp; A similar 
	explanation describes the effect on the planets as they revolve around the 
	sun.</p>
	<p>Newton was able to apply the same laws to describe the apple, the moon, 
	and the planets.&nbsp; When the book came out, it caused a sensation.&nbsp; 
	Within about 40 years or so everybody was a Newtonian.</p>
	<p>Newton became a celebrity.&nbsp; He became president of the Royal Society 
	in 1703 and was knighted in 1705.&nbsp; He published <i>
	Opticks</i> in 1704. &nbsp;He produced revised editions of the <i>Principia</i> in 
	1713 and 1726.</p>
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	<p>The <i>Principia </i>provided the solution to a 10,000 year old problem.&nbsp; 
	It showed people what they could do with science.&nbsp; Using a system of 
	laws, theorems and proofs it provided a universal system for understanding 
	the physical world.&nbsp; It is taken as a model by other fields of science 
	like chemistry but also as a model in the social realm.&nbsp; In politics it 
	triggered a search for mechanisms or systems.&nbsp; It engendered a belief 
	that there were systems which people could find that would be better.&nbsp; 
	By extension it supported the growth of the belief that there should be more 
	revolutions, more change, as people discovered better systems.</p>
	<p>The Enlightenment of the 18th century was strongly influenced by Newton's 
	revolution.&nbsp; The goal of philosophers like Voltaire, Rousseau, Locke, 
	or Hume was to understand everything and that included the social world.&nbsp; 
	The search was on to find universals, one of which was equality.&nbsp; The 
	application of equal rights, a universal set of principles, as well as the 
	concept that our understanding of the world could change underlay a century 
	of political, social, and economic revolution and our own Constitution.</p>
	<p>The 19th century built upon Newtonian physics with each science working 
	toward finding and describing the system that connected the minutia of 
	observation and away from minor models that described limited sets of data.&nbsp; 
	Newton is responsible for the physics behind the space program, meteorology, 
	hydrology, and a vast array of other scientific and social changes that 
	depended on the model in the <i>Principia</i>.&nbsp; Even the Einsteinian 
	revolution follows the Newtonian model of searching for a set of universal 
	laws that will govern everything and supports the principle that revolutions will continue to 
	happen as knowledge is not static.</p><hr width="60%"><hr width="40%">
	<p>The audience was able to examine a copy of the first English edition of 
	the <i>Principia</i> published in MDCCXXIX.</p>
	<p>&nbsp;</p>
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          <td width="100%"><blockquote><font face="Verdana,Arial,Helvetica" size="-1"><br>Citation:<br><br>"Newton:&nbsp;  Planets, Apples, and Scientific Revolution."&nbsp;  Summary of a lecture by Theodora Kalikow.&nbsp;
University of Maine at Farmington, September 28, 2005.&nbsp;  Retrieved _______.&nbsp; 
&lt;http://hua.umf.maine.edu/Reading_Revolutions/<br>Newton.html&gt;.  <br><br>URL:  <a href="http://hua.umf.maine.edu/Reading_Revolutions/index.html">http://hua.umf.maine.edu/Reading_Revolutions/index.html</a>  <br><br>Marilyn Shea, 2005<br><br>

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