GST 2420: Atoms and Stars
An Historical Introduction to Astronomy, Physics, and Scientific Discovery.
Fall 2002, Section 983, Call Number 16050
Agenda 12 for 11/20

  1. Announcements:
    1. Day scheduled as a Friday (no Atoms and Stars class) - November 27
    2. Student Evaluation of Classes (SET) on December 4.
    3. Course web site: http://www.cll.wayne.edu/isp/drbowen/aasf02 (also links from Pipeline).
    4. Online Life at WSU with links at http://www.cll.wayne.edu/isp/drbowen/OnlineLife.
    5. For Essay 2, article by Bronowski starts on Reader Pg 254, article by Nissani on Pg 261. Read these for next week.
    6. Online grade reports are working. To enable yours, give me a password on the small slips of paper provided.
      1. To get your online grade report, go to the course web site (see above), click on the link "Get online grade report," type in your first name, last name (both as the University has them, or as they are on the name checkoff sheet) and password, then click on the "Get grade report" button. The reports are updated by me, manually, so may lag behind the work you just turned in, and attendance for the last class. Also, note the date above the report; this is the date that the database was last updated.
      2. Attendance grade assumes that your attendance pattern remains unchanged.
      3. The lab grades are entered as "OK" = 95, "+" = 100 and "-" = 70. The overall lab grade assumes that you will turn in all labs, and that your pattern of grades will continue.
      4. The assumption is also that your Essay 2 grade will be the same as your Essay 1 grade, and your Final grade will be the same as your Midterm grade. A missing Essay 1 gets averaged in as a zero.
  2. Science in the news
    1. Protecting earth from meteorite strikes. First thought was to blast them with nuclear explosions, but now astronomers are thinking about a gentler nudge while the meteorite is very far away. Accurate knowledge of orbits required.
  3. Final exam
    1. New questions for list - fields coming together, example of light, carry over from old
      1. Describe one case in which two expanding fields of science met. What happened within each field. What happened outside of these fields?
      2. (#10 from Midterm list) Compare the contributions of Aristotle and Archimedes to modern science. How did their approaches or methods differ? How does each compare with modern approaches to science?
    2. What should be on info sheet? My goal here.
    3. Start review.
  4. Readings: Atomic theory of Matter. "Second Scientific Revolution"
    1. Steps:
      1. Invention of classical chemistry and Antoine Lavoisier (1743 - 1794, pronounced lah vwahz YAY). Up until this time, chemistry was almost entirely a black art. It was important economically, but chemistry was mainly done through recipes. Lavoisier's edge seems to have been twofold: (a) a strong interest in theory, and (b) excellent technique in weighing  accurately and completely enough to detect missing gases.
      2. The idea of an element - cannot be broken down, other substances are made up of it, but it is not made up of anything else. Still the Aristotelian elements - air, earth, fire and water.
      3. Stephen Hale, 1727 - could heat many substances and drive off large quantities of "air" (we would call it gas today) - air was not a single substance.
      4. Long path to Lavoisier's reformulation of chemistry. Some key events:
        1. Discoveries of different airs (gases), modern names in parentheses:
          1. common air (air), flammable air (hydrogen), good air (oxygen), fixed air (carbon dioxide). Air was not a simple element but a mixture (roughly 80% nitrogen and 20% oxygen). Also, flammable air formed water when burned, so water was not an element.
        2. Electrolysis of water to produce flammable air and good air - water was not an element but a mixture.
        1. Oxygen theory of combustion (combustion is combination with oxygen), new set of names for chemicals based on this. Changed "air: to "gas" and used "air" for former common air.
      5. (Idea of an atom. Very small, gas is mostly empty space. At same temperature and pressure, all gases have the same number of atoms in each volume, different densities are due to the different weights of the atoms. In a solid, atoms are fixed rigidly to each other, in a liquid the atoms stay close together but can slide around. Atoms have different weights and shapes, but mostly just blobs. 90 naturally occurring types, these are the elements.)
      6. Atomic model, for gases. John Dalton (1766 - 1844)
        1. (From Gerald Holton, Introduction to Concepts and Theories in Physical Science, 1973) Dalton apparently became convinced of the existence of atoms through a misreading of Newton's Principia. Dalton was interested in why gases did not stratify by density in the atmosphere, and thought that Newton wrote that atoms in a gas attracted each other gravitationally, and that this is what kept them up.)
        2. General "Law of Definite Proportions." Chemical reactions always involved fixed proportions, supported the idea of atoms.
        3. Noticed that running a current through water gave off twice as much hydrogen as oxygen, assumed (correctly) that this was because of the number of atoms of each; water had two atoms of hydrogen for every atom of oxygen. But oxygen weighed more, so oxygen atoms weighed more than hydrogen atoms. In this way, worked out the atomic compositions of many chemicals, and the relative weights of atoms., without ever detecting an atom directly.
      7. Ludwig Boltzmann, end of 19th century. Physicist had never accepted idea of atoms, did not believe in them. Boltzmann, a physicist, was one of the first. Worked out Newtonian mechanics for a gas of atoms and molecules - Statistical Mechanics, together with J. Willard Gibbs. Found that it gave the same results as Thermodynamics, but also explained how those results came about. But physicists sharply rejected these ideas, and this may have contributed to Boltzmann's suicide in 1906. But now Boltzmann is honored as a pioneer, ideas are very important, although significantly modified by Quantum Mechanics.

        This is a second example of expanding circles of scientific knowledge meeting - Newtonian mechanics (three laws) meeting the atomic theory of matter.
    2. Global warming from the early elements C, H, O, N.
      1. Fossil fuels are C and H, air is O and N. C and 2 O's combine to give CO2, carbon dioxide, H and O combine to give H2O, water. Everything else, such as N and O forming NO2, is a poison or severely degrades the environment. But CO2 is a greenhouse gas, traps heat in atmosphere, warms up the earth. Sunlight and heat radiation (infrared) are both electromagnetic radiation, but light can penetrate the atmosphere, while infrared (given off by warm objects) cannot, and gets reflected back to earth.
      2. Facts:
        1. CO2 will do this.
        2. The earth is warming.
        3. Strong scientific consensus that man-made CO2 is causing the warming. There is a serious question about how much heating is going on.
      3. If second and third world industrialize to our level (and it is their announced intention to do this, and our announced intention to help them do it), then levels of CO2 will rise to six times current levels.
      4. We know enough about the physical world to know that significant warming will occur.
      5. We do not know enough about biological world to predict what the effects will be, but there will be many.
      6. Also, we do not know enough about our society, including our economy, to predict what those effects will be.
  5. Readings (Bronowski and Nissani on the nature of knowledge and science.
    1. For me, Bronowski's chapter is very powerful, but personally I am not ready to blame all evil on those who claim certain knowledge. (Example)
    2. Both readings emphasize the uncertainty in scientific knowledge - it is what I have called "provisional" - just the best we can do at the present time, subject to revision.
    3. Both emphasize the social nature of science, Nissani more explicitly, when he says that science is conducted by people (scientists) who are just as fallible as other people, and that the progress comes through discussion, disagreement (often vigorous) and debate. Bronowski implicitly recognizes the social nature of science in describing the discussions in Gottingen.
    4. Both describe the incremental nature of science, accumulating knowledge bit by bit. I describe this with the ?expanding circles" analogy. For me, the expanding circles suggest the additional questions of what happens when expanding circles collide (many examples, two presented in this course), and what happens as the expanded and merged and circles fill the plane of facts - i.e. will scientific knowledge just take over?
    5. Bronowski introduces statistical analysis, used today in industry for Quality (Demming) and Six Sigma. Demming said to monitor the width of this curve; if sigma increases, something is wrong in your manufacturing process. Six Sigma is based on the fact that only one in a million cases lies outside the six-sigma range (-3 to +3).
    6. Bronowski also introduces the famous Heisenberg Uncertainty Principal that is one of the foundations of Quantum Mechanics.

      The uncertainty (sigma) in position x times the uncertainty in velocity is equal to Planck's constant (1.0545 × 10-34 in metric or mks units) divided by the mass of the object or particle whose mass and velocity are on the left side of the equals sign. This is "exceeding small" unless the mass is also very small. The mass of an electron is 9.11 × 10-31 kg, and we often want to know its position very well, say one billionth (10-9) of a meter.

      The Uncertainty Principal undercuts the idea of the Newtonian "clockwork universe:" if we know the positions and velocities of all of the objects, accurately enough, and the forces between them, at any one time, we can project them forward to any future time. The Universe, in this picture, is deterministic. The Uncertainty Principal says that we cannot know the positions and velocities accurately enough in order to have "clockwork" determinism.
    7. Nissani deals at length with the falsifiability criterion, and with the many and diverse views of science, from outside of the scientific community, and also (correctly, in my view) says that these outside views are largely ignored inside the scientific community. In addition he says (correctly, in my view) that we all rely on the technological products of science, even while some dismiss and others ignore the scientific basis of those technologies. I think it deserves to be pointed out that science and technology were largely disconnected throughout most of history, or worse. Technology often "drove" science (e.g. Torricelli). Only in the twentieth century did science start to drive technology in a pervasive way. In my description of expanding circles of scientific knowledge, this is due to the expanding circles of science filling up such a great part of the plane of knowledge.
  6. Lab IV - electrolysis of water - splitting water into hydrogen and oxygen.
    1. The electrolysis takes awhile. Start the experiment going, then we will continue reviewing for the Final, and interrupt the review when the test tubes are full of "air."
    2. Equipment is better than what is described in the lab manual. AC Power Supplies replace batteries. Be careful with the little strips at the free ends of the wires. These are the aluminum electrodes - no need to cover wires with aluminum foil.
    3. Lay the experiment out carefully. Plan how you will remove the test tubes, strike the match and insert it in the test tubes. Keep the test tubes upside down to trap the gas, especially when removing them from the apparatus. No sense in taking any chances; be careful to hold the test tubes away from your body, and not pointed at your face, when inserting the match.
    4. Fill the beaker most of the way with water. dissolve baking soda first, then fill up test tubes and invert them in the water. Then connect wires. Make sure to use the DC connections, not the AC connections. After the connections are made, dry everything off, turn the power supply on, and set it for about 12 Volts.
    5. Be gentle when removing the tubes from the apparatus for testing with the matches. Waving them around, or letting water just splash out may dissipate the gases you have collected.
    6. When I did this at home, the volumes were equal, not 2:1. I don't have an explanation for this. There was a pop when putting a burning match in the tube over the positive wire (hydrogen) and a strong but brief flame in the tube over the negative wire (oxygen).
    7. Cleanup: douse matches in water, let me take that trash home to throw away. Rinse glassware. Wipe up spills and stains. Thank you.