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3/9/08 Atoms and Stars, Class 8 1
Schedule:• No signin• Review (Q & A) up to 6 PM• Midterm (about one hour)• Return graded work and
turning work in• Class (about 1½ hour)• Lab 13 (Pg 77, Lab Manual)
Atoms and StarsIST 2420
Class 8, March 9Winter 2009
Instructor: David BowenCourse web site: www.is.wayne.edu/drbowen/aasw09
Atoms and Stars, Class 8 3
Agenda day: Saturday 3.14• Assignments and passbacks• Handout: Questions for Final• “Expanding circles” – a model of scientific
progress• Physical Science and natural disasters• Upcoming assignments• Lab 13: Parallax
3/9/08
Atoms and Stars, Class 8 4
Lab 8 Pt 2
• If hypothesis is given or asked for, it should be clearly separatedo New paragraph at least
3/9/08
Atoms and Stars, Class 8 5
Lab 8 Part 2
Dropping objects• Can from different heights
o Impact increases with greater height (speed), not weight
• Can and blocko Aristotle said heavier object would fall faster, in
proportion to the weight, because the force is the weight
o Did not turn out this way: why waits for Newton
3/9/08
Atoms and Stars, Class 8 6
Expanding CirclesWhat Happens When Science Progresses?
• “Science is Progressive” (two meanings)• Science always has a boundary• Science makes progress beyond boundary
o Past discoveries become new tools (barometer)o Extend theories beyond current experiments
• Important in science, but can be misleading• Some scientists say that any religion is incompatible
with science, but actually, that is an extension (more)
• Old questions still important; new answers
3/9/08
Atoms and Stars, Class 8 7
Expanding Circles
• After rise of science, most revolutionary scientific advances (late 19th and 20th centuries) extend scope, leave core valid (at least numerically – watch for Quantum Mechanics later)1. Newton (our common idea)2. Special relativity (max speed, energy = mass)3. General relativity (gravity, creation of space)4. Quantum Mechanics (uncertainty at atomic
level and smaller)3/9/08
Atoms and Stars, Class 8 8
Expanding Circles Q16• “Expanding circles of
knowledge” (DB)o Exact shape (circle)
unimportant – “blob”o Science moves boundary
outo Progresses (expands) by
extending known into new territory• Theory and experiment
3/9/08
Atoms and Stars, Class 8 9
Expanding Circles
Review:• Greek and later science developed isolated
areas of knowledgeo Air and water pressureo Speed of lighto Falling and sliding objectso Motions of the planets and stars
3/9/08
Atoms and Stars, Class 8 10
Expanding Circles
• Implication #1: eventually, expanding circles must meet and overlap Q16o Different approaches, different theories – will
not agree
3/9/08
Atoms and Stars, Class 8 11
Expanding Circles
• Implication #2: circles could meet and fill the space Q16o What happens then?
3/9/08
Atoms and Stars, Class 8 1212
Expanding Circles
• Implication #1: eventually, expanding circles must meet and overlap
• Three examples in this course: Q15o Isaac Newtono James Clerk Maxwello Ludwig Boltzmann
3/9/08
1313
Expanding Circles
• Implication #1: eventually, expanding circles must meet and overlap
• Possible interactions:o Withdrawalo One wins out over the othero Compromiseo Synthesiso ???
Atoms and Stars, Class 83/9/08
1414
Expanding Circles
• Expanding Circles – my conclusion Q15o When two domains meet, become fused into one with a
bonuso Not a compromise – both areas transformed
• Implications:o This is additional evidence for science
• If theories were imaginary, different imaginations would ruleo Hard to attack just one area of science, since they are
becoming more tightly tied together• Creationists and Intelligent Design advocates finding they have
to attack 4.5 billion year age of earth, Big Bang, etc. (readings), radioactive dating
Atoms and Stars, Class 83/9/08
1515
Expanding Circles (Review)
• Implication #2: circles could meet and fill the spaceo What happens then?o DB: what happens is what makes science
valuable
Atoms and Stars, Class 83/9/08
1616
Expanding Circles
• Implication #2:o Joined circles expand to fill plane of
knowledge (Q17)• In earlier times, science and technology developed
independently– When there were interactions, technology drove science– Some improvement of scientific instruments resulting
from theory in Newton’s time (1687 Principia, 1704 Opticks)
• In 19th century, influence became mutual– Example: contribution of Thermodynamics (movement of
heat) to steam engine efficiency
Atoms and Stars, Class 83/9/08
1717
Expanding Circles
• Implication #2: (Q16, Q17)o In 20th century, science began to drive
technology. These 20th-century technologies were predicted by science well ahead of time:• Atomic / nuclear energy (didn’t understand until
later that E = mc2 made this prediction)• Laser• Computer, transistor, microchip, Internet• Radio, TV, telephone, cell phone• Jet and rocket engines
Atoms and Stars, Class 83/9/08
1818
Expanding Circles
• Implication #2: (Q16, Q17)o Science driving technology (cont’d):
• Industry uses science to develop products better-faster-cheaper
• Designs are science-based, often simulated on computers before prototyping
• Theory – what makes science valuable, not only for scientists, but for society
• WMU study: Michigan has to do better at this to be competitive– Manufacturing– Life sciences
Atoms and Stars, Class 83/9/08
1919
Expanding Circles
• Implication #2:o Science driving technology (cont’d):
• Many scientists believe that US lead in science and technology is disappearing– Degrees granted– Science prizes e.g. Nobel– Scientific articles published– Patents granted, etc.
• … and that this threatens our technology and economy
• Probably need at least a core of people who understand “big picture” for innovation
Atoms and Stars, Class 83/9/08
20
Natural Disasters #1
• Hurricanes, tornadoes, earthquakes, tsunamis, mudslides, avalanches
• Hurricanes best understoodo Rising air over warm ocean – spirals
counterclockwise as seen from above in Northern Hemisphere due to earth’s rotation
o Picks up water vapor, condenses out higher up
Atoms and Stars, Class 83/9/08
21
Natural Disasters #2• Hurricanes best understood
o When water condenses, air heats again – “fuel”o Strength: indicated by low pressure in the eye
• No storm, 30” Mercury – if eye gets to 27”, get out of there! (Katrina)
o Very large size, winds to about 200 mpho Called typhoons in Asia
• Tornadoes also circular, form over land, smaller but higher winds (about 300 mph)o Less well understood than hurricanes
(“supercell”)Atoms and Stars, Class 83/9/08
22
Natural Disasters #3
• Earthquakeso “Plate Tectonics” gives general explanationo Earth molten when formed ~ 4.5 BYAo Cooled, surface condensed into continents (thin
“plates”) floating on molten core (“magma”)o Currents in core, like currents in boiling water,
carry plates, like the skin on cooking puddingo Plates crash into each other earthquakes
Atoms and Stars, Class 83/9/08
23
Example: North & South America were joined to Europe and Africa, magma is boiling up at Mid-Atlantic Ridge, pushing them apart.
Geography and species from before split match across Atlantic ocean
Atoms and Stars, Class 83/9/08
24
Natural Disasters #5
• Earthquakeso As plates crash, tension in “crust” builds up longer time between quakes larger quakeo Cannot presently tell when quake will happen
• Tsunami – wave formed from underwater earthquakeo Sensors, warning system, disaster network can
move population out – Hawaii and Alaska monitoring centers
o No such system in Asian 2004 tsunami, in place now
Atoms and Stars, Class 83/9/08
25
Natural Disasters #6
• Mudslideso Deforestation and development mean
vegetation on hillsides being cut backo People living in these areas due to growth in
populationo Heavy rains weaken hillsideo Depth of mud can be hundreds of feet or moreo Can be foreseen, but weak societies cannot act
Atoms and Stars, Class 83/9/08
26
Natural Disasters #7
• Avalanches• Depends on layers of snow resting on icy
crustso Each melt, freeze, snow cycle adds a layero Then a sharp loud sound can trigger avalancheo We can tell when conditions are righto We can trigger avalanches by, say, firing a
cannon. Makes area safe at that time.
Atoms and Stars, Class 83/9/08
27
Natural Disasters #8
• Natural Disasterso At present, we cannot predict or control theseo We are learning a lot about them
• Earthquake and hurricane construction codes• Modern buildings in California much better against
quakes, in Florida against hurricaneso Prediction will come first, control is a maybe
Atoms and Stars, Class 83/9/08
28
For next class
• Next classReader: “The Planet Mars and Kepler’s Three Laws of Planetary Motion,” “The Crime and Punishment of Galileo Galilei”o Read the manual, Experiment 10 (Lenses and Telescope)o Turn in report on Experiment 13 (Parallax)
• Essay 2 review coming up next classo Summing up the whole semester, does this course have a
core, and if so, what is it?• Also Questions for Final, Information Sheet
Atoms and Stars, Class 83/9/08
29
Experiment 13• Pg 77, Lab Manual• Parallax – line of sight changes angle when object
viewed from different positionso Geocentric – no parallax for stars, earth does not
change position (fixed at center)o Heliocentric – earth does change position, we should
see parallax for stars.o Lack of observed parallax an early argument against
heliocentric systemo But really, stars too far away for crude angle
measurements then – we see it now• Also, the most direct distance measurement for
objects we cannot travel to
Atoms and Stars, Class 83/9/08
30
Experiment 13
• Follow lab manual, answer all questions• Two measurements of distance to an object:
parallax measurement and direct measuremento Are the two equal? Angle measurement is
“weak link.” Can probably measure to ½ºo Repeat distance calculation with larger angle -
½º• Check and show all calculations• Check with Instructor if results disagree
Atoms and Stars, Class 83/9/08
31
Experiment 13 - Parallax• A-B = “Baseline”• Measure distance from Baseline
to Po Two methods, direct and parallax
• Parallax measurements:o Distance A to B (ruler)o Angle A (protractor)o Angle B (protractor)o (Check: one angle > 90º, other < 90º)o Then calculate distance to P using formula in
manualAtoms and Stars, Class 83/9/08
32
Experiment 13
Atoms and Stars, Class 83/9/08
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