Dated Age of Earth at
4.55 billion years old
Geologists, like Clair Paterson,
are going to use the concept of
a half-life to calculate the age of
the earth.
Darn useful stuff, this chemistry
238 Uranium - parent
207 Lead - daughter
Half life - 4.5 billion years
(convenient, isn’t it).
Image from the Iowa Geoscience Education Information Network.
Clair Patterson (1922-1995)
So, 1/2 of all uranium was
converted to lead in meteorites,
which is why we know age of
Earth.
True scientific discovery renders the brain incapable
at such moments of shouting vigorously to the world
"Look at what I've done! Now I will reap the benefits
of recognition and wealth." Instead such discovery
instinctively forces the brain to thunder "We* did it" in
a voice no one else can hear, within its sacred, but
lonely, chapel of scientific thought.
- C. Patterson on discovering the age of the Earth
* "the generations-old community of scientific minds."
Image removed
due to copyright:
Thomas Midgley
(available here).
T. Midgley
T. Midgley discovered that by
adding lead to the gas reduced
engine knocking.
The problem is that this put an
enormous amount of lead in the
atmosphere. When tested in
1965, lead amounts were 1000
times higher than background
levels.
Used his prominence as a
scientist to get lead removed
from gasoline. Lead is a
neurotoxin, particularly for children*.
It is estimated that the
amount of lead in Americans
has gone down by 80%.
Image from the Iowa Geoscience Education Information Network.
*Low level effects are IQ
deficits, learning disabilities,
behavioral problems, stunted
or slowed growth, and
impaired hearing
In the 1965 paper entitled "Contaminated and Natural
Lead Environments of Man," Patterson made his first
attempt to dispel the then prevailing view of lead not
being a major problem.
Image from the Iowa
Geoscience Education
Information Network.
Paterson’s letter to an science journal editor about
his role:
The enclosed manuscript does not constitute basic research and it lies within a
field that is outside of my interests. This is not a welcome activity to a physical
scientist whose interests are inclined to basic research. My efforts have been
directed to this matter for the greater part of a year with reluctance and to the
detriment of research in geochemistry. In the end they have been greeted with
derisive and scornful insults from toxicologists, sanitary engineers and public
health officials because their traditional views are challenged. It is a relief to
know that this phase of the work is ended and the time will soon come when
my participation in this trying situation will stop
A super nice guy!
I got nothing bad to say.
Image from the Iowa Geoscience Education Information Network.
Clair Patterson (1922-1995)
Scientific Ways of Knowing
Induction -> Approach is observing (Empiricists)
1. Natural Observation – observation of natural system
without manipulation
2. Experimentation – observation of natural system with
manipulation
Deduction -> Approach is modeling (Theoreticians)
1. Numerical modeling –quantitative models designed to
make predictions of geometry or behavior of natural
systems
Major problems with doing “hard stuff” (or, how to
succeed in life)
-ability to concentrate
-ability to prioritize (do not underestimate the time
needed to master the more quantitative material)
- willingness to undertake tasks that are not
overtly enjoyable or entertaining
-willingness to accept criticism
-willingness to accept the fact that one may not
immediately succeed in all tasks
Now on to a big deal in the development of modern science
I dig the wig.
Image source: Wikipedia.
Isaac Newton (1642-1727)
Time’s People of the Century
20th: Albert Einstein
19th: Thomas Edison
18th: Thomas Jefferson
17th: Issac Newton
Every day is a bad hair day.
Image removed due
to copyright: Time
magazine coverEinstein as Person
of the Century.
“Newton is the man of the century for this reason: by
imagining--and proving--a rational universe, he in effect
redesigned the human mind. Newton gave it not only
intellectual tools undreamed of before, but with them,
unprecedented self-confidence and ambition.
Image source: Wikipedia.
… In a sense, all the
change that shaped the
world until the onset of
modernity had its origins in
Newton's mind. For what he
showed was this: the
universe is knowable and
governed by universal laws-therefore predictable,
therefore perfectible by
human reason and will.”
- from Time magazine
Random person stuff:
-Newton never married, had children, or had a romantic
relationship.
-Had a dog named “Diamond”.
-Was an alchemist (people who
wanted to turn lead into gold).
Probably had mercury poisoning.
-Secretly did not believe in the
divine trinity, but would have been
removed from his post if he had
admitted it. He did believe in God.
Image source: Wikipedia.
- He was a bit of a jerk to other
scientists (o.k., he apparently had
an ego the size of Oklahoma).
In short, Newton almost single-handedly invented
a new “way of knowing”…
NUMERICAL MODELING
Modeling uses a theoretical approach, which in
turn uses deductive logic
Deductive logic - using rules to understand
examples
Given Model/Concept  Expected Data
Therefore, theoretical approaches set up a set of
rules and predict the consequences of those
laws given a particular situation.
Analysis requires pretty good math skills, because it is
only in quantitative analysis that one can rigorously
follow through the consequences of a set of general
laws.
Luckily, Newton was reasonably good at math (ok, he
was really good - he invented calculus)
"Taking mathematics
from the beginning of
the world to the time
when Newton lived,
what he has done is
much the better
part." —Gottfried
Leibniz
..and I hate
his guts (and
I didn’t steal
calculus from
him)
Image source: Wikimedia Commons.
Leibniz
So, what’s the deal with the apple
Image source: Wikipedia, courtesy of Gregory H. Revera.
Newton saw an apple fall and the
moon, and realized that the same
force that made the apple fall also
kept the moon in orbit.
Image source: Wikipedy.com.
A definite
“aha” moment
Image source: Wikipedia,
courtesy of Abhijit Tembheka.
Newton did a lot, but the most significant was the book:
Philosophiae Naturalis Principia Mathematica (1687), but
referred to by those in the know as “Principia”
"The Principia is pre-eminent
above any other production of
human genius."
—Pierre-Simon Laplace
Image source: Wikipedia.
And here is the amazing thing it is written in plain English.
The Three Laws of Principia
Law #1: Every body continues in its state of rest, or of
uniform motion in a right line, unless it is compelled to change
that state by forces imposed on it.
Law #2: The change of motion is proportional to the motive
force impressed; and is made in the direction of the right line
in which the force is impressed.
Law #3: To every action there is always opposed an equal
reaction; or, the mutual actions of two bodies upon each other
are always equal, and directed to contrary parts.
So simple
Image source: Wikipedia,
courtesy of Abhijit Tembheka.
A talking fruit
Newton’s Law #1:
It took centuries for scholars to collectively shake off the
notions that the “natural state” of an object was “at rest” and
that the constant motion could only happen with continual
pushing. It was not so obvious to realize that in fact, constant
motion only happens with no pushing at all. The abstract
concept of an object moving at uniform velocity (constant
speed and direction) in the absence of any outside force
crystallized with the work of Galileo, but Newton said it the
best.
Luckily, the first law is now
simple to understand
because of the advent of
air hockey.
Image source: Wikipedia, courtesy of Tbuckley89.
Newton’s Law #2:
This law defines what a force is, and suggests that it is
proportional to the acceleration of the object. It also suggests
that Force has both a magnitude and a direction.
Oh, and the constant of proportionality is the mass of the
object. Hence,
Force = Mass x acceleration
In truth, this was probably already figured out by Galileo.
A good portion of engineering
is based on this idea (for
better or worse)
Image source: Wikipedia, courtesy of Paul Anderson.
Newton’s Law #3:
The third law is the most subtle and surprising of the three
laws. As Newton adds, “Whatever draws or presses another
is as much drawn or pressed by that other.” It says that forces
always come in pairs, action and reaction. There is no such
thing as a single, isolated force vector, alone without another
partner somewhere. The implication is that nothing – no
outside agent – is capable of acting on things while being
immune from being re-acted on in turn. That is, no action can
be taken in isolation.
Like, man, I feel so connected to the
world because, like, everything is
interwoven and the sun and the moon
and even Neptune is a little attracted to
me and so, like, that means….
Image source: Wikipedia,
courtesy of Abhijit Tembheka.
A new-age fruitcake
fruit
The laws (short form)
• Law #1: Every body continues in its state of rest, or
of uniform motion in a right line, unless it is compelled
to change that state by forces imposed on it.
• Law #2: The change of motion is proportional to the
motive force impressed; and is made in the direction
of the right line in which the force is impressed.
• Law #3: To every action there is always opposed an
equal reaction; or, the mutual actions of two bodies
upon each other are always equal, and directed to
contrary parts.
Theoretical approaches
They are as useful, insofar as they make
useful predictions.
All models are wrong;
some models are useful
Image source: Faculty page at UW-Madison.
G.E. Box
So, for example, let’s say that we want to figure out what
Galileo could not measure accurately enough: How long
does it take a object to fall vertically (55 m)?
Law #1: There must be a
force on the ball, because
it starts to move downward
Image removed due to
copyright: Man
appearing to kick Tower
of Pisa (available at
Flickr).
Law #2: It must move
downward at a constant
acceleration, because
F=ma (IMPORTANT!)
Law #3: The Earth is
moved very slightly toward
the ball, because forces
come in pairs.
If acceleration is constant, we
can make some calculations
Distance = initial position
+ initial velocity * time
+ ½ (acceleration * time2)
OR, if position = 0 and initial velocity= 0,
then:
Distance = ½ (acceleration * time2)
acceleration = 9.8 m / sec2
Notice how the dropped ball moves farther during the
same time steps, as it moves downward.
The same equation can be used to calculate
the ramp experiments, to see what the answer
should “theoretically” be:
Distance = ½ (acceleration * time2)
But, in this case,
acceleration = (9.8 m / sec2) sin (q)
q is the inclination of the ramp
This was Galileo’s trick; he slowed down the experiment by using
the inclined ramp to decrease the constant acceleration.
How do we know this equation?:
Newton’s second law!
After Newton’s three laws were understood, the universe
became a predictable place. For example, people
immediately started using this approach to hurl
cannonballs at each other.
Note that the cannonball shot at 45° goes furthest.
Are Newton’s three
laws really laws?
Image source: Wikipedia.
A brief review:
• A scientific law attempts to describe an observation in
nature
• Whereas a scientific theory attempts to explain it
• A scientific hypothesis is an educated guess
Are Newton’s three
laws really laws?
Yes! Newton’s three
laws describe
observations. In this
example, they also
provide the framework
for how to usefully
think about them.
Image source: Wikipedia.
But, Newton’s laws are not correct (in detail).
Newton’s three laws aren’t technically correct. Albert Einstein
hypothesized that if material travels really fast, really weird
things can happen.
Laws, as well as theories, are subject to change!!
But, Newton’s laws are still
extremely predictive tools for
relatively slow speeds.
186,000 miles per
second isn’t just a
good idea, it is the
law*.
*Note this is funny
– if it is funny –
because it equates
a scientific law with
a law law.
Image source: Wikipedia, courtesy of Alfred Eisenstaedt, Life magazine.
Science is:
1. tentative and subject to change;
2. influenced by social and cultural
norms; and
3. the product of human imagination and
creativity.
Should we just give up because science
is tentative and subject to change?
"The young specialist in English Lit ... lectured me
severely on the fact that in every century people
have thought they understood the Universe at
last, and in every century they were proved to be
wrong. It follows that the one thing we can say
about our modern 'knowledge' is that it is wrong.
... My answer to him was, '... When people
thought the Earth was flat, they were wrong.
When people thought the Earth was spherical
they were wrong. But if you think that thinking
the Earth is spherical is just as wrong as thinking
the Earth is flat, then your view is wronger than
both of them put together.”
- Isaac Asimov
Science is uncertain
History has taught scientists some humility: If
something as obvious as Newton’s three
laws is incorrect (as Einstein showed),
then one must retain an attitude of
skeptism.
As a result, good scientists (and thinkers of
all traits) share some common intellectual
traits, including:
1. Intellectual humility
2. Intellectual integrity
3. Confidence in Reason and Evidence
Image source: Wikipedia.
4. Fairmindedness
“I do not know what I
may appear to the
world; but to myself, I
seem to have been
only like a boy,
playing on the
seashore, and
diverting myself in
now and then finding
a smoother pebble or
prettier shell than
ordinary, while the
great ocean of truth
lay all undiscovered
before me.”
Image source: Wikipedia.
Science is the process of
separating the
demonstrably false from
the probably true.
Michael Zimmerman,
Minnesota Citizens for Science Education.