Atoms and Stars
IST 2420
and IST 1990
Class 14
Winter 2006
Instructor: David Bowen
Course web site: www.is.wayne.edu/drbowen/aasw06
IST 1990 Moodle: techtools.culma.wayne.edu/moodle
4/19/06
Atoms and Stars, Class 14
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Agenda
• Assignments, passbacks, initial signin sheet
• Pick up:
o Notes for Class 14
• Class information
o Special Grade Request if much work will be late
•
•
•
•
Review of readings
Emphasizing main points one more time
Updates: natural disasters & bird flu
Lab 11: The Orbiting Bottle
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Upcoming …
• Tonight is the last regular class
o Essay 2 due
o Review for Final Exam
• April 26: nothing that night but the Final
Exam
• Opportunities for extra help:
o Review Session during class
o 5 – 6 PM before Final (April 26)
o Telephone, email, set up a time
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My new cell phone number
• 248-376-9848
• This is the number to call during 5 – 6 PM
office hours
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Semester is Ending!
• If you have been relying on being able to
turn work in late, it is late!
o Alternatives: D, E, I, X, drop – see counselor!
• Getting ready for Final:
o Read Information Sheet carefully – a lot of
information there
o Look at Final Topics carefully
o Use Review Session!
• Final Where-Is handed out at the previous class
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Course Grades
• If you are turning a bunch of work in at the
end, I may not get it graded in time for the
regular grades (see the Syllabus).
• If this is you (turning it in late), what grade
do you want for the regular grade? E, X, I
• Fill in the Grade Request form (get a copy
from me) to let me know – otherwise it’s
my choice.
• You can withdraw (W) through April 25
• Medical Withdrawal
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Your Current Status
• Grades I have for you:
o Online Grade Report, link off the course web
site (see first slide)
o Enter first name, last name, password the get
report
• Grade you are headed for:
o Grade What-If on course web site
• Ask for help with these if you are having
problems
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Makeup for Final Exam
• Let me know by email that you want a
makeup, within 24 hours after the Final
(University regulation)
• Date / Time Friday May 26 6 PM on
campus
• Watch for later email about building and
room (but I won’t send you an email unless
you send me the email at the top bullet)
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Lab 7 Questions at end
A.
B.
C.
D.
Weight does not set flotation
Specific Gravity < 1 (water)  float
Ice floats  Specific Gravity < 1
Specific Gravity useful in deciding what
material an object is made of
E. Archimedes right, displaced volume =
object volume
F. If S.G.object < S.G.liquid, then object floats in
liquid.  dumbbell floats in Mercury.
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Lab 11: Orbiting Bottle
• If your two results (A & B) for the
horizontal (inward) force, FH, agree, then
your data are consistent with Newton’s
Laws (including Universal Law of
Gravitation).
• See Theory section for the proof of this
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Brain Candy…
Wormhole
• A theoretical possibility within Einstein’s
General Theory of Relativity (1916)
o A shortcut through 4-D space-time that could
dramatically speed travel between points
connected by the wormhole, and into the future
o Requires an undiscovered form of exotic matter
that may not exist, with negative energy density
– a “white hole,” contrasts with a black hole
o Wormhole could collapse on the traveler
• http://en.wikipedia.org/wiki/Wormhole
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Wormhole
From Wikipedia (see link on previous slide)
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Global Warming (cont’d)
• What to do? Options:
o Nothing. Live with it. (Physical and ecosystem
consequences not known)
• Humans can adapt quickly, natural world cannot –
evolution is slow, but humans are free of evolution
• Many past examples of disasters from warming
• Natural world is too complex for us to make good
predictions in from our present science
o Cosmetic actions. Cite uncertainty in effects,
call for more research
• May never have 100% certainty of the effects
o “Invisible hand” of market
4/19/06
• Trade CO2 permits
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Global Warming (cont’d)
• Options (cont’d):
o Limit CO2 production
• Increase energy efficiency, use waste energy, switch
to low-carbon fuels (natural gas) away from coal
and petroleum
o Remove CO2 once it is generated
• Sequestration – pressurized underground or under
deep ocean (will warming release it?)
• (DB) Recent poll says US thinks scientists
are confused about Global Warming. NOT!
o Deliberate confusion caused by industry groups
opposed to controls – citing 2 or 3 out of 2,500
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Readings: Icecaps and Hurricanes
Evidence for Global Warming:
• Thawing icecaps
• Coral bleaching
• Hurricanes
• Melting glaciers
• Desertification
• Rising sea levels
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DB: That’s not all…
• Many worldwide resource issues – “the
human footprint”
o Water (drinking, irrigation, industrial), food,
farmland, population (6 billion  9 billion),
living in unsafe places, petroleum, trash,
development, health care, education, rights
• Managing the human footprint will be a
major, continuing issue
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Re-emphasizing Main Points
• Two pillars of science
o Experiment: makes science reliable
• Scientists led astray by logic (Aristotle) and belief
(church and geocentrism, Inquisition)
• Experiments base science on direct experience
o Theory: makes science valuable
• Once you have a reliable theory, it tells you the
answer in advance, can use it as technology
• Two quotes from Copi, Reader Pg 8
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Re-emphasizing Main Points
• I have the experiments in this course to:
o Give you direct experience
o Illustrate experiments described in class
o Illustrate social nature of science within the lab
groups
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Updates
• Bird flu:
o Some concern over transmission via domestic pets in
rich countries
o Also being spread through smuggling
o Anthony Fauci (NIH): probably no disaster here, BUT
• Natural disasters:
o Hurricane season of 2005: with better measurements,
more hurricanes
o In addition to hurricanes, warm Gulf of Mexico also
important in tornado formation
• Tornadoes generated when warm air from Gulf meets cold air
from Northwest
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Updates (cont’d)
• Plate tectonics:
o Determines location of mineral resources and
fossil fuels
• Mineral resources brought near surface by old zones
of rising magma
• Fossil fuels generated when organic matter covered
over before it rots, “cooked” when drawn down to
warmer depths (but not hot – like baking a turkey)
then brought back near surface so we can find it
– Temperatures increase going down into the earth
• Plate tectonics does both of these
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Updates (cont’d)
• Tenth planet?
o In Class 5, mentioned “tenth planet” 2003
UB313 nicknamed “Xena,” larger than Pluto
o That size based on inference from brightness
o New direct measurement says Xena about the
same size as Pluto
o Inference from brightness fooled because Xena
is highly reflective
o Now, Pluto and Xena will probably be either
accepted as planets or demoted, as a pair
o Meaning of “planet” still being debated
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Uncertainty Principle (Repeat)
• No practical
effect at
macroscopic level
o A philosophical problem with The Mechanical
Universe and with “The God’s eye view” or
The Clockwork Universe over age of universe
• Important at atomic and molecular level
o Uncertainties are large on atomic scale
o What underlies our reality is strange
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Readings: Knowledge or
Certainty
Jacob Bronowksi
• Absolute certainty is impossible in science
o Looking at an object with infrared, then visible,
then x-rays should yield greater detail. Infrared
is very blurry, visible is pretty good, but x-rays
are too high energy to be focused. Perfect detail
of “God’s-eye” view is impossible
o Statistical uncertainty in measurements - Gauss
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Knowledge or Certainty
• 1795
• Science is discussion and argument
preceding knowledge
• Also Uncertainty Principal 1927 Werner
Heisenberg – cannot locate particle exactly
o Irreducible uncertainty or fuzzy focus
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Knowledge or Certainty
• No practical
effect at
macroscopic level, but a philosophical
problem with The Mechanical Universe and
with “The God’s eye view”
• But certainty leads to tragedy – Nazis
• (DB) Certainty and power combined
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What is Science?
Moti Nissani, What Is Science?
• Difficult or impossible to give a dictionarytype definition for science
• (DB) Working scientists rarely think about
the history or philosophy of science
• Start with philosophy of Thales – free
inquiry
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What Is Science? (cont’d)
• Then hypothesis and experiment (Torricelli)
• Falsifiability – reason and logic have not
been not sufficient to discover the truth in
science (DB: belief, either)
o But contradiction by experiment does not
always mean rejection of hypothesis – can lead
to reexamination of experiment or modification
of hypothesis
o Scientists “on the trail” have personal concerns
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What Is Science? (cont’d)
o Scientists “on the trail” have personal concerns
• Argument and community lead to progress
o Semmelweiss and deaths in maternity ward
•
•
•
•
•
•
4/19/06
Neighboring ward far safer
Did priest’s visit scare patients?
Washing hands – doctors did dissections beforehand
This fixed the problem
Profession slow to accept this change
Even scientists can be closed-minded, resist change
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What Is Science? (cont’d)
• Theories unify many hypotheses and
experiments
o Price is often inaccessibility to non-scientists
• Scientists usually not concerned with these
issues or with philosophical uncertainty
• Science many not be perfect, but it can still
be very good
• Many use technology but not the scientific
foundation
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Physical Science: Current Status
• Newton’s Laws, Maxwell’s Equations and
similar classical theories (before ~ 1900)
describe world we know and see
• For things the size of molecules and
smaller, need Quantum Mechanics
• Very fast, need Special Relativity
• Very heavy, need General Relativity
• All three have weird things going on
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Special Relativity
• For fast-moving objects
o
o
o
o
Max speed = c (speed of light)
Objects foreshortened
Time slows down
But the traveling person says the same about
you!
o Space and time  space-time
o E = mc2
 light has mass, is bent by gravity
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General Relativity
• For very heavy objects
o Space and time warp, cause gravity
o Perihelion (closest approach to sun) of
Mercury’s ellipse not fixed as in Newton’s
Laws, but advances 43 seconds of arc per
century (observed), other effects in addition
o Light bent twice as much as Special Relativity,
observed 1918
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General Relativity (cont’d)
• “Einstein Halo” –
light from far
galaxy bent by near
galaxy
• Variation on
gravitational lens
• 12 found so far
•
Picture: New York Times, 12/6/05,
Pg D4 (Science)
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Quantum Mechanics
• At molecular level and smaller, waves and
particles merge – everything is both
o Wave – spread out, cannot contain it
o Particle – have it or don’t
o Q.M.: wave gives chance of “catching” particle
• Cannot be made certain
• Uncertainty Principle
o Carries over to regular world, makes clockwork
universe impossible over age of universe
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Quantum Mechanics (cont’d)
• Accounts for properties of ordinary
materials
o
o
o
o
o
Theoretical: keeps matter from collapsing
Color
Solid (strength), elastic, gaseous
Solid state electronics – semiconductors
Forces – due to exchanges of particles
• No Newtonian “action at a distance”
• E.g. electrical force carried by photons – particles of
light
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Combinations
• Fast (S.R.) and heavy (G.R.) – OK, since
Special Relativity contained within General
Relativity
• Fast (S.R.) and small (Q.M.) – these two get
along well – together, predict anti-particles
• Heavy (G.R.) and small (Q.M.) – conflict
o No “Quantum Theory of Gravity, ” union of both
• General Relativity is the theory of gravity
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Combinations (cont’d)
• Heavy (G.R.) and small (Q.M.) –
mathematical conflict
o Competing theories of gravity – “embarrassing”
• G.R.: gravity caused by masses warping space-time
• Q.M. – gravity due to exchange of “gravitons” (not
found yet)
o “String Theory” might unite these two
4/19/06
• “Theory of Everything” – accelerating expansion(!)
• Matter and energy composed of elemental vibrating
strings and membranes
• Eleven dimensions, seven curled up too small to
experience directly – may have indirect experience
• Theory still developing, no unique experimental
evidence yet Atoms and Stars, Class 14
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Three waves of science?
1. Physical science – the subject of this course –
mature, quantitative (95%)
•
Very controversial when it was new
• 1600 – 1800 AD, although very long roots & still developing
•
Now pretty much settled for everyday objects
2. Biological or life science – qualitative (30%?)
•
Much newer, still controversial publicly, but for
scientists it is settled
• 1800 – 1935 AD
•
•
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Coming into general use in society & economy
Will qualitative change to quantitative?
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Three waves of science?
3.Cognitive science – how emotions and the
mind work – just starting (5%)
o Will be as controversial, if not more
o Potential for controversy: Science of Desire :
The Gay Gene and the Biology of Behavior &
The God Gene (spirituality) / Dean Hamer
• Spirituality predestined for some, denied to others?
• A single gene is unlikely to be the sole cause
o Will call into question how we view ourselves
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The end of the ride
• Strong dose of the value of science here
• One more time, about science:
o Two pillars – repeatable experiment (what makes it
reliable) and explanatory theory (what makes it valuable)
• Developed 1600 – 1800 AD: Copernicus to Dalton
o Developing hypotheses and theories is creative
o Has a boundary but expands aggressively
 not a complete basis for living
o
o
o
o
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Now drives technology
We all use it
Conflicts with some, but not all, religious beliefs
People of all ethnicities have been able to contribute
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Review for Final
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