Atoms and Stars
IST 2420
and IST 1990
http://www.is.wayne.edu/drbowen/aasW05
Class 11: March 30
Plagiarism
• Starting tonight, all essays on diskettes
• I believe I am seeing plagiarism in Essays.
o
Primary effect: lack of self-confidence
• You should read the section on plagiarism in
the Syllabus before doing this
• If A copies from B, both are at fault.
o
o
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If I cannot tell who did what, I will be impartial
Plagiarism applies to (wrong) ideas as well as
words
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Plagiarism
• I have received plagiarized lab reports.
Memo to Department
o First time: treated as report not turned in (can
be redone)
o Second time: assignment failed, no re-do
o Third time: course failed
o
• Starting with this week’s lab session,
Reports must be turned in the following
week.
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Lab 9B
3
• C   (a  b) this is wrong, intentionally
7
o
Correct formula is very complicated
• Real point of lab – strength of authority
• Points for report
Realizing there is a disagreement
o Checking measurements and calculations
o Reporting the disagreement
o
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Lab Reports
• As of tonight:
Lab Reports that have only a data sheet get a
grade of “D.”
o Lab Reports without an original data sheet get a
maximum grade of “C”
o
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5
From Last Week
• Why do scientists think that space-time is
curved (i.e., General Relativity)?
Advance of the perihelion (point of closest
approach to sun) of Mercury – ellipse rotates in
space, not allowed if Newton is 100% right
o Bending of light by objects
o Gravitational and cosmological red shifts
o Black holes
o
• Many consistent with modifications to G.R.
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Error in Class 4
• Slide 18: Aristotle inferred spherical earth
from its shadow on the moon (phases of
moon). This is correct – he did.
o
I also said this was the modern explanation for
the phases of the moon – it is not
• Modern explanation is that the moon is
illuminated by the sun, and we see it from
different angles as it circles us and we circle
the sun
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About Science…
• Science involves discourse between
scientists – shared language, purpose,
methods. Variations within scientific fields.
o
Study science now by studying scientists
• When a new area is being explored,
common for consensus to change, even
drastically
• Even after things settle down, do not expect
100% agreement
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8
Epistemology
• Several times you have asked me “Is this
(absolutely) true?” I tend to hesitate with
questions like this – here is why.
• Epistemology – the study of knowledge –
why do we accept things as true?
• Properties we would like for knowledge/truth:
Eternal – unchanging
o Universal – the same everywhere
o (Also that it be understandable)
o (Also that it be right, of course)
o
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Epistemology
• Science flunks “eternal”
o
Scientific truth is provisional – subject to change
• Religions have problems with “universal”
How can different religions differ, if there is one
truth?
o For science and religion, Galileo agreed with
modern Catholic doctrine – there is one truth
o
• Reinterpret Bible if it disagrees with accepted science
o
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Today, religions generally ignore disagreements
with each other
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“Expanding Circles”
• So far, disconnected areas of knowledge:
Air and water pressure
o Speed of light
o Falling and sliding objects
o Motions of the planets and stars
o
• Each area (circle? blob?) expands
• What happens next?
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Expanding Circles
• Eventually, expanding circles must meet
and overlap
o
Before meeting, each area has a unique
approach and theories – areas will not agree
• Possible interactions:
Withdrawal (NOMA in science)
o One wins out over the other
o Compromise
o Synthesis
o
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Expanding Circles
• Case of Newton (and Kepler) uniting
terrestrial and celestial mechanics
New theory
o Each is understood more accurately and
causally
o A bonus – applies to all motion, calculus,
applied in technology, model for new science
o
• Other examples coming up
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Readings
Atomic Nature of Matter, Hewitt
• All matter is atoms
Atoms are elements – “indivisible” – mostly
empty
o 109 types total, 90 are natural, rest radioactive
o
• Each type has its own properties, e.g. weight,
reactions
o
Hydrogen most common atom in universe
• Rare by itself on earth
o
Life primarily C, H, O, N
• Atoms small enough to be invisible - waves
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Atomic Nature of Matter
• First direct evidence 1827 Robert Brown
Noticed spores jiggling under microscope
o “Brownian motion” – bombarded by molecules
o Now we have more direct evidence
o
• Atoms bond into molecules – many types
Molecules - compounds
o Molecules have separate properties from atoms
o Burning is combination with O
o
• New - modern automobiles very little CO
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Atomic Nature of Matter
• 1811 (Amedeo) Avogadro’s hypothesis
At same T & P, equal Vs of gas have equal #s
o Each atom, molecule heavier  gas heavier
o
• Amu = atomic mass unit
• C 12 amu, H  1 amu, O  16 amu, U  238 amu,
H2O  18 amu – also combine in gm, lb etc.
• Atom has electrons orbiting nucleus
Electrons – volume but very little mass
o Nucleus – mass but very little volume
o
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Atomic Nature of Matter
• Electron, e – negative charge, flow of electrons is
electrical current
• Nucleus has neutrons, n (no charge) and protons, p
(positive charge)
o
Cube 3/8” would weigh 133,000,000 tons
• Like charges repel, unlike charges attract
o
o
Nucleii positive, repel each other
Atoms neutral; #e = #p
• #e not = #p under special circumstances
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Atomic Nature of Matter
• Electrons in shells (2, 8, 18, …)
If shells filled, element is inert
o Unfilled shells determine activity
o #p = atomic number, chemical characteristics
o
• Same element even if atom loses or gains electrons
• Antimatter – anti-electron (1932), antineutron, anti-proton
o
Annihilate  100% energy (light)
• Nuclear reactions normally 1%
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Readings - Chemistry
• Chemistry developed after Newton (physics)
Alchemy – transmutation of elements
o Medicine
o Industry – much demand for chemicals 1700s
o Mechanical approach from Descartes & Newton
o
• 1700 still Aristotelian elements
Earth – fixed volume & shape
o Water – fixed volume only
o
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Chemistry
• 1700 still Aristotelian elements
Air – volume & shape expanded to container
o Fire passed through container walls
o
• 1727 – Stephen Hale: “fixed” air released
from solids, much interest
• 1749 Jean-Jacques DeMairan evaporated
liquids (e.g. ether) in a vacuum, froze water
But liquids supposed to evaporate into air
o Fire combined with liquid = air? Many types?
o
• Water could be solid, liquid, vapor –differ by fire?
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Chemistry
• How could “big four” be elements?
• 1750s Joseph Black experiments with
“magnesia alba,” gave off “fixed air” that
extinguished flame (CO2), denser than
“common air,” turned limewater cloudy
o
Use limewater test to show fixed air came from
fermentation & charcoal combustion, would not
support life
• “Fixed air” became specific name for this gas (CO2)
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Chemistry
• 1766 Henry Cavendish: “inflammable air” H
• 1772 Joseph Priestley obtained “fixed air” in
other ways, demonstrated solubility in water
(& taste – birth of carbonated beverage
industry)
o
Many other types of air – “dephlogisticated air” O
• Phlogiston theory of combustion – burning releases
phlogiston – from Germany, industrially useful
• When air is saturated with phlogiston, combustion and
life cease
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Chemistry
• Antoine Lavoisier (1743 – 1794)
Graduated in law but continued science studies
o Accurate weighing, also many practical results
o (Calcination – turn a metal to powder (“calx”) by
heating in air below melting point – phlogiston
theory explained this as driving off phlogiston)
o But Lavoisier’s weighing showed that weight
increased, for all metals – a problem for
phlogiston theory of combustion
o
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Chemistry
• Calx of mercury (oxide of mercury) when
heated gave off air (gas) but supported
combustion and life
o
Priestley found this air better (5×) for combustion
and life than “common air” (air) – “eminently
respirable air”
• Lavoisier had assumed it was common air
o
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Lavoiser confirmed this, but common air was
then a mixture
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Chemistry
• 1778 Lavoisier showed this air also formed
acids, named it oxygen (“acid former”) (but
we now know that hydrogen makes acid)
• 1783 Cavendish’s assistant told Lavoisier
about Cavendish’s experiment of applying
spark to inflammable air (H), finding dew
which was identified as water
o
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Lavoisier – water was not an element,
combination with oxygen for all combustion
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Chemistry
• Lavoisier named flammable air “hydrogen”
for “water former”
• Lavoisier and others formed new chemical
terminology – speaking well was like
reasoning well
Oxide – combination with oxygen
o Names indicated amount of oxygen (ous > ic)
o
• Sulfurous acid H2SO3
• Sulfuric acid H2SO4
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Chemistry
• Lavoisier terminology
Gas – any vapor
o Air – the atmosphere, a mixture (80% N, 20% O)
o Fire was caloric (no correct theory until 19th
century – started by Count Rumford)
o
• John Dalton (1766 – 1844), meteorologist
o
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Converted to chemistry when he understood air
was a mixture – why didn’t different gases
separate by gravity?
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Chemistry
• John Dalton (1766 – 1844), meteorologist
Also gases dissolved in water proportional to
pressure – why?
o Hypothesized gases composed of atoms, each gas
interacted with itself
o “Law of definite proportions” – chemicals
combined by weight in simple ratios
o Dalton proposed formulae based on these –
chemical atomism
o
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Common Writing Problems
• Functional grammar
o
o
o
o
o
o
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Rules of grammar have a purpose – to transmit
meaning
Rules of grammar are always changing
Different grammars for different groups
Get too far from the group’s grammar and you
are not understood (must change with changes)
The further you get from the group’s grammar,
the harder it is to understand you
Being able to use good standard grammar is
like dressing well for a job interview
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#1 Reason for Writing
• To organize your own thinking
#1 Way to Good Writing
• Have something you want to say
More Examples and Details
• www.is.wayne.edu/olgt or The Everyday Writer
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Organization
• Many possibilities for organization
Historical
o Logical
o Specific to general, or general to specific
o Combination
o
• Signal transitions from one topic to another
o
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Paragraphs help here
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Quick-and-Easy Organization
• Write body first
• One you have figured out what you are
going to say (the Body), write the
Introduction and Conclusion afterwards
• Body should have general statements and
specific examples and quotes
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Sentences
• A sentence:
Verb (easiest to find - action)
o Subject (did the action)
o Complete thought
o (starts with capital, period at end)
o
• (Y/N) Because he hit the ball.
• (Y/N) John hit the ball.
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Sentences
• Is it a sentence? Consider it all by itself.
• Common sentence problem #1:
o
Sentence fragment – something that starts with
a capital and ends with a period but is not a
sentence
• Because he hit the ball. John ran to first base.
• Fix by joining to main thought with a comma (,)
– Because he hit the ball, John ran to first base.
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Sentences
• Is it a sentence? Consider it all by itself.
• Common sentence problem #2:
o
Run-on sentence – two or more sentences
written as one
• John hit the ball he ran to first base.
• Fix by breaking into two sentences
– John hit the ball. He ran to first base.
• Or by joining with semicolon (;) to show causality
– John hit the ball; he ran to first base
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Number (singular/plural)
• Both subject and verb have number
o
If these are not the same, signals conflict
• Members join the club
• A member joins the club
• “One s”
• Without a reason, do not change number
from sentence to sentence
o
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(Bad) People should take care of their health.
You should take your vitamins.
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Tense (past, present, future)
• Without a reason, do not change tense from
sentence to sentence
Citations
• “Scientific investigation is not, as many
people seem to suppose, some kind of
modern black art.” (Huxley, 1)
• Cite the source even if you are paraphrasing
o
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Ideas: very important in academia, trace them
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Punctuation
• Apostrophe (‘)
o
o
Contraction
Possession (‘s or s’)
• Some words inherently possessive, no ‘ (e.g. theirs)
o
Never for pluralization (in 1600s, not in 1600’s)
• Lists
Separate list items with commas (last one is
optional)
o If any list has a comma inside an item, separate
items with semicolon
o List can be singular even if many members
o
• This group of authors travels by bus.
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Wrong Word
• Some words are commonly confused –
memorize or use list or dictionary
o
o
o
o
o
o
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its Vs it’s
whose Vs who’s
their Vs there
too Vs to
accept Vs except
Many, many more
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39
Lab – Experiment 10; Lenses
•
•
•
•
General – light is easier to see than bunny
Lenses are in tissue paper inside envelopes
Labels on envelopes do not mean anything
Each envelope has five lenses – keep track by
type
Three convex with
increasing thickness
o One concave
o Other types: plane, plano-convex, plano-concave
o
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Lab
• Exercise I.
o
For this part, start with the lens touching the
paper. As you move the lens towards you, if
you see a dramatic change in the image, keep
the lens closer to the paper.
• Afterwards – what happens as you move lens past
the point of dramatic change?
What type of lens is magnifying? Reducing?
o For magnifying lens, how does focal length
vary with curvature?
o
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Lab
• Exercise II: image properties
Real (can be projected on a screen) Vs virtual
(behind lens, can be seen but not projected)
o Inverted (upside down) Vs non-inverted
o Magnified (larger than object) Vs reduced
o
• Measure focal length in mm
o
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Measuring focal length
for reducing lens
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Lab
• Exercise III:
Two lenses are objective (closer to object) and
eyepiece
o Good telescope – focal length for objective is
longer than for eyepiece
o Good idea to make screen for objective: cut
hole in card, slightly smaller than lens, tape lens
to card, bend card to stand lens up
o
• Do not do the WRITING ASSIGNMENT
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For Next Week
• Reader: 254 – 275 (Bronowski and Nissani
articles)
• Lab Manual: Experiment 11, Pp 64 - 77 on
Centripetal Forces and Gravitational
Motions
• Turn in Lab 10 report
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Future Due Dates
• Essay 2 due April 13
o
The Everyday Writer (DIS standard) and
writing web site http://www.is.wayne.edu/olgt,
link to Writing Guide
• Last regular class April 20
o
Work turned in after this date may not be
included in regular grade
• April 27 Final Exam (NOT April 23)
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IST 1990
• Essays based on set questions, taking
readings into account
Get a set from me
o Tell me which question you are answering,
before title
o
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46
End
Lab starts now, for everyone! Not like last week.