3/9/08Atoms and Stars, Class 81 Schedule: No signin Review (Q & A) up to 6 PM Midterm (about one hour) Return graded work and turning work in Class (about

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


Lab 8 Pt 2

• If hypothesis is given or asked for, it should be clearly separatedo New paragraph at least

3/9/08


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


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


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


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


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


Expanding Circles

• Implication #1: eventually, expanding circles must meet and overlap Q16o Different approaches, different theories – will

not agree

3/9/08


Expanding Circles

• Implication #2: circles could meet and fill the space Q16o What happens then?

3/9/08


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


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


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


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


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


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


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


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


• 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


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


24


• 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


25


• 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


26


• 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.


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• 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


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


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


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


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


Documents

3/9/08Atoms and Stars, Class 81 Schedule: No signin Review (Q & A) up to 6 PM Midterm (about one hour) Return graded work and turning work in Class (about