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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>
- <font size="+1">
- Newton: Planets, Apples, and Scientific Revolution<br><br>
- <font size="+0">Theo Kalikow</font></font></font><p> </p>
-
- </font>
- <table border="0" width="60%" id="table2">
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- <td>
- <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>
- <td>
- <p align="left">
-
- <a href="pictures/Newton/1480wl.jpg">
- <img border="0" src="pictures/Newton/1480w.jpg" width="275" height="400"></a></td>
- </tr>
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- <td>
- <p align="left"> </td>
- <td>
- <p align="center"><font face="Verdana,Arial,Helvetica" size="-1">
- Newton shown behind an armillary sphere with Earth at the
- center. Click to enlarge.
- </td>
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- </table>
- </center>
- <font size="+0">
- <p><font face="Verdana,Arial,Helvetica" size="-1">
- The following is a summary of Dr. Kalikow's presentation:</font></p>
- </font>
- <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>!
- Newton, is of course, the person who made mass a scientific and lawful
- concept. 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. 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. All over the world, each civilization carried out
- traditions of astronomy whether for agriculture or travel. What is
- common to all of these traditions is the assumption that the earth is the
- center of the universe. If you get outside and look at the sky, that
- is what it looks like. This is called the two-sphere universe -- the
- earth in the center and a second sphere rotating around it. Very early
- in history, people realized that the earth was a sphere, not flat. 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. The earth was the center and all bodies would fall toward it.
- The heavens were perfect and motion in the heavens would be perfectly
- circular. If there were no planets we might still be there. The
- planets move in peculiar ways given the Aristotelian method. Ptolemy
- in 150 AD collected all the observations he could find and made ingenious
- mathematical models to explain the planetary motions. (<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. There was no physics to support it but Copernicus
- solved the problem of the planets with a sun centered universe. If
- Earth is a planet going around the sun, how do you explain the motions on
- earth and the motions in the heavens? Tycho Brahe attempted to solve
- the problem and refine the data by making more exact observations. He
- used very very large instruments to increase the degree of accuracy of
- positional measurements. 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. Kepler studied Brahe's data to
- create a system that would fit the data. 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. 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. 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. He used it to look at all sorts of things. 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. He
- saw the phases of Venus and the moons of Jupiter. The moons of
- Jupiter provide a model of how the solar system could work. Galileo
- had the first new data and method of seeing the universe. He didn't
- like the ellipses of Kepler, preferring circles. He still didn't have
- the physics to explain the motion of the planets. If the sun is the
- center of the solar system and the earth revolves around it, why don't
- things fall off the earth? That's how things stood until the time of
- Newton. </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. 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. In 1660 a group of scientists including Wren,
- Boyle, Hooke, and Moray who had been meeting to discuss scientific matters
- established the Royal Society. People in other countries were also
- working on similar issues -- Descartes, Spinoza, Leibnitz -- and carried on
- lively correspondence throughout Europe. </p>
- <p>In 1684 Halley goes to Newton to ask him about a question circulating at
- the time. If a force falls off as a square of the distance what shape
- would the orbit take? Newton said ellipse. How do you know?
- Newton said that he had proved it previously. Halley wants to see the
- proof and nags Newton until he finally sent it to him. Halley takes it
- to </p>
- <div align="center">
- <table border="0" width="30%" id="table3">
- <tr>
- <td>
- <font face="Verdana,Arial,Helvetica" size="-1">
- <img border="0" src="pictures/Newton/1554w.jpg" width="416" height="400" align="left"></td>
- </tr>
- <tr>
- <td>
- <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>
- </tr>
- </table>
- </div>
- <p>the Royal Society and continued to nag Newton to write out his major
- theories. 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. He didn't
- show any signs of genius at an early age. He graduated from Cambridge
- and would have stayed on but 1665-1666 was a plague year and the
- universities closed. Newton stayed home for two years and thought
- about things. This appears to be the time that he created much of his
- later work. He didn't write much and didn't publish anything. He
- returned to Cambridge and two years later became the Lucasian Professor of
- Mathematics at age 26. 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. He passed light through a
- prism to produce a rainbow of colors. 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. In 1671 he published his paper on optics and
- light.
- 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. His correspondence increased. But he
- found that when he wrote to other scientists they would write back and often
- wouldn't agree with him. He didn't like that. He tended to stay
- in Cambridge and avoid active contact with others. Thus, Halley had to
- come to him. History justifiably gives Halley great credit for the the
- <i>Principia</i>. 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. The book is set up like a geometry with propositions,
- proofs and diagrams. It looks like geometry, but in fact all through
- the book Newton is using the calculus. The fundamental concept is the
- concept of limits. What happens when a fundamental quantity, ratio or
- proportion moves toward a vanishing point or starts at nothing and
- increases. 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. He used observation but relied on mathematics to
- refine his physics. This is the first comprehensive use of what we
- call the scientific method: 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. These laws can be used to derive the predictions for
- all matter. For instance, he described the law of inertia: a
- body at rest tends to remain at rest, a body in uniform motion in a straight
- line will go on forever. It is indifferent which state of motion is
- true. Those are the only two natural states of motion. The
- circles of Copernicus are excluded from the natural state.</p>
- <p>Newton also invented the concept of mass. 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. Another law from
- Newton is universal gravitation. 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>
- <font face="Verdana,Arial,Helvetica" size="5">
- <p align="center">
- <img border="0" src="pictures/Newton/gravityformulaw.jpg" width="250" height="153"></p>
- </font>
- <font face="Verdana,Arial,Helvetica" size="-1">
- <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.
- The laws apply to everything, including apples. 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. The apple is
- just like the moon. It and the earth are also attracted to one
- another, so why doesn't it fall? 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. At every point on the orbit, both laws are at work.
- The result is that the moon is trapped into an orbit. 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. When the book came out, it caused a sensation.
- Within about 40 years or so everybody was a Newtonian.</p>
- <p>Newton became a celebrity. He became president of the Royal Society
- in 1703 and was knighted in 1705. He published <i>
- Opticks</i> in 1704. He produced revised editions of the <i>Principia</i> in
- 1713 and 1726.</p>
- <font size="+0">
- <p> </p>
- <p> </p>
- <p> </p>
- </font>
- <p> </p>
- <p align="center"> </p>
- <p> </p>
- <p>
- <img border="0" src="pictures/Newton/1525w.jpg" width="353" height="400" align="right"></p>
- <p> </p>
- <p>The <i>Principia </i>provided the solution to a 10,000 year old problem.
- It showed people what they could do with science. Using a system of
- laws, theorems and proofs it provided a universal system for understanding
- the physical world. It is taken as a model by other fields of science
- like chemistry but also as a model in the social realm. In politics it
- triggered a search for mechanisms or systems. It engendered a belief
- that there were systems which people could find that would be better.
- 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. The goal of philosophers like Voltaire, Rousseau, Locke,
- or Hume was to understand everything and that included the social world.
- The search was on to find universals, one of which was equality. 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.
- 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>. 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> </p>
- <p align="center"><a href="pictures/Newton/1630wl.jpg">
- <img border="0" src="pictures/Newton/1630w.jpg" width="400" height="380"></a></p>
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- <a href="pictures/Newton/1634wl.jpg">
- <img border="0" src="pictures/Newton/1634w.jpg" width="400" height="300"></a></td>
- <td align="right">
- <font face="Verdana,Arial,Helvetica" size="-1">
- <a href="pictures/Newton/1625wl.jpg">
- <img border="0" src="pictures/Newton/1625w.jpg" width="394" height="300"></a></td>
- </tr>
- <tr>
- <td colspan="2" align="center">
- <font face="Verdana,Arial,Helvetica" size="-1">Click on book images
- for enlargement</td>
- </tr>
- </table>
- <p><font face="Verdana,Arial,Helvetica" size="-1">
- </font><br><br><br>
- </p>
- <center><table border="6" cellpadding="0" cellspacing="0" style="border-collapse: collapse" width="80%" id="decorative" bgcolor="#cccccc">
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- <td width="100%"><center><table border="6" cellpadding="0" cellspacing="0" style="border-collapse: collapse" width="100%" id="credits" bordercolor="#111111" bgcolor="#cccccc">
- <tr>
- <td width="100%"><blockquote><font face="Verdana,Arial,Helvetica" size="-1"><br>Citation:<br><br>"Newton: Planets, Apples, and Scientific Revolution." Summary of a lecture by Theodora Kalikow.
- University of Maine at Farmington, September 28, 2005. Retrieved _______.
- <http://hua.umf.maine.edu/Reading_Revolutions/<br>Newton.html>. <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>
- </blockquote></td></tr></table></center>
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