Its Time to Reinvent Introductory Physics

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Its Time to Reinvent Introductory Physics
It is first about Nature, and only later about
History, Mathematics and Philosophy
Larry Curtis
Distinguished University Professor of Physics
and Astronomy University of Toledo
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What we are doing now?
Prof. Robert Holcomb, Cornell University The
current standard model syllabus reflects a 1950
world view. New topics are simply draped
across the existing skeleton. Left untouched
are evolutional ways of thinking about physics
developed over the past 60 or 70 years.
Physics Education Research accepts the current
model focuses on ways to teach within
the confines of the status quo.
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John Rigden the only way departments of
physics touch future national leaders is through
introductory physics courses. Those
equation-driven courses do not, in my judgment,
qualify as a science education. the value of
an introductory physics course, 6 months after
the final exam, is negligible. I wager that
adults who once took an algebra- or
calculus- based introductory physics course are
unable to discuss common physics phenomena and
cannot demonstrate a better understanding of
basic physical concepts than can those who never
saw the inside of a physics classroom.
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HOW PHYSICS LOOKS TO A BEGINNING STUDENT
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What should be the public awareness of Physics?
Is Physics a coherent body of useful contemporary
knowledge? Or
only a Method of Inquiry unchanged since the Age
of Enlightenment?
Intro. Phys. I to American
Revolution Intro. Phys. II to American Civil
War Modern Phys. to the Great Depression
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Relearning the ignorance of the Enlightenment
Planetary motion (Copernicus, Galileo, Brahe,
Kepler 1500-1600)
Newtons laws (Newton 1687)
Electricity (Coulomb 1777)
Magnetism (Gilbert 1600, Oersted 1819)
Line spectra (Kirchhoff 1859)
Kinetic theory (Maxwell 1860)
Relativity EM (Voigt 1887)
Atomic confirmation (Einstein 1905)
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 The only justification for a historical
treatment is when you must explain how things got
to be so messed up.   Many textbooks introduce
the topic through history. Why? Because there
is a compelling need to explain how things came
to be so muddled and confused, and you won't
understand the situation unless you appreciate
the history.
- Gary
Bradshaw
Until you know it yourself, it doesnt matter who
discovered it!
First things first, but not necessarily in that
order.
- Dr. Who
(J.
Flanagan A. McCulloch, Meglos)
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Stephen Jay Gould We have to extract meaning
out of the confusion of the world around us. We
do it by telling stories, and by looking for
patterns. And whenever we see a pattern, we have
to tell a story about it.
David Layzer There is a peculiar synergy
between mathematics and ordinary language.
Without adequate verbal support, formulas and
diagrams tend to lose their meaning without
formulas and diagrams, words and phrases refuse
to take on new meanings.
Richard Dawkins if solid things are mostly
empty space, why don't we see them as empty
space?" The answer lies in our own evolution.
You might think that our sense organs would be
shaped to give us a true picture of the world
as it really is. Instead they have been shaped
to give us a useful picture, designed to
understand the mundane details of how to survive
in the stone-age African savannah
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Discover Magazine - October 2005 Issue
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The Force Concept Inventory
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the concept of force has reached the end of its
life cycle (suggesting) its disbarment from the
inventory of fundamental concepts in
physics. Max Jammer, Concepts of Force, 1957
In all methods and systems which involve the
idea of force there is a leaven of artificiality
there is no necessity for the introduction of
the word force nor the sense-suggested ideas
on which it was originally based.
Peter G. Tait,
Dynamics, 1895
If people were to learn to conceive the world in
a new way, without the old notion of force, it
would alter not only their physical imagination,
but probably also their morals and politics.
Bertrand
Russell, The ABC of Relativity, 1925
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Quotes from Force-Trained students
How can a rocket work in outer space where there
is nothing for the force to push on?
The moon doesnt fall to earth because the
centrifugal force holds it out.
If weight is gravitational force, and orbiting
astronauts are weightless, then they must be
outside the range of gravity.
We know that nuclei are small because
?-projectiles miss them and go mainly forward.
If nuclei were large, ?-particles would hit them,
feel a force, and bounce backward.
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(Ohio State Board of Education 12/10/02)
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Are the problems we assign even realistic?
____________________________________
Am. J. Phys. 71, 1152 (2003) dispute / R.K.
Adair 73, 184 (2005).
1. Viscous drag nonlinearly couples horizontal
vertical solve numerically.
2. Aerodynamics of backspin dominates the range
achieved.
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A lousy approximation!
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THE NATURE OF MATTER _____________________________
____________________________ All matter consists
of little bits of positive and negative
electricity in perpetual motion attract each
other at short distances repel each other when
pressed too close together. ______________________
__________________________________ The most
important discovery ever made. If all other
scientific information we know were lost in some
cataclysmic event, and only this information
survived, all could be rediscovered in a very
short time.  
- Richard P. Feynman
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Iron atoms positioned on a carbon surface
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Second Quantization - The Discrete Photon
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700 keV Li beam (v4.4 mm/ns) incident on a thin
(3 ?g/cm2) carbon foil. The blue light is
H-like 4f-5g in Li2 (?4500Å, ?3 ns, ?x1.3
cm). The green light is He-like 2s 3S-2p 3P in
Li (?5485Å, ?44 ns, ?x19 cm).
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Can we pictureattractive and repulsive
interactions without the force concept?
Quantum Field Theory is conceptually easy!
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ACTION-AT-A-DISTANCE Exchange of a gauge boson
Particle exchange can produce both attraction and
repulsion. It is intermittent, like rain on the
roof. The Force concept requires an average
over a time interval.
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Interactions between any two particles involves
all the particles in the universe.
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Strike a billiard ball so it rolls w/o slipping?
If we use the line of action of the impulse as
the fulcrum, there are NO torques !
The angular momentum is the same before and after
the impulse.
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Speed at which a sliding ball rolls w/o slipping ?
at release
alley exerts friction
rolls w/o slipping
Use conservation of angular momentum about the
point-of contact with the floor, so there are
no torques.
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Intrinsic Action
? Quantized h/2 building blocks
? Odd 1st quant. (inter. Part.) / Even 2nd
quant. (gauge bosons)
? Odd FD stat. / Even BE stat. /
Together MB stat.
? Least Action gives conservation laws,
dynamics
? Energy Action/Time Momentum
Action/Length
? Least Action Quantization Uncertainty
Principle
? A Lorentz Invariant
? Mechanical action ? parity
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LEAST ACTION What is the path between
(x1,y1,t1) and (x2,y2,t2) ?
Total Energy Kinetic Energy Potential Energy
Action Kinetic Energy
Potential Energy ?t The particle does
whatever it wants, but we see the path where the
Total Action summed over all points adds up to
the smallest value.
On this path the Total Energy is the SAME for
each point
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Principle of Least Action Interactive
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Nature chooses the space-time path of minimum
action
and that path must contain an integer number
action quanta
Action canonically welds Momentum-to-Length

Energy-to-Time This leads to an Uncertainty
Principle between
them
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Nature has revealed a beautiful secret!
The behavior of the Universe becomes very simple
if it is described in a way in which space and
time are symmetric.
What makes it seem hard, is the fact the we must
live our lives by standing at a point in space
and watching time pass, but not the reverse.
Its like our perspective in riding the Earth
around the Sun, which seems as if the Sun were
going around us. However, the heliocentric
equations are much simpler.
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Model for a current in a wire
Woldemar Voigt 1887
Variously delayed photon arrivals make lengths
appear shorter and charge appear denser.
If q moves with the electron drift, the positive
charge appears denser, giving a repulsion.
If q moves opposite to the electron drift, the
negative charge appears denser, giving an
attraction.
This is magnetism, and results from relativity at
speed 0.1 mm/sec !
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TIME Time is what keeps everything from
happening at once.
- Attributed to John Archibald Wheeler
Quoted by
Woody Allen
Time flies like an arrow fruit flies like a
banana.
- Groucho Marx
Backward turn, turn backward, O time in your
flight. Make me a child again, just for
tonight.
- Elizabeth Akers Allen
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Electron-Positron Pair Creation and Annihilation
Once created, e and e- are stable until
annihilated
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time
Are they all really the same electron?
Future
Here-Now
space
Past
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Laplacian Determinacy A Costly Mistake
Pierre Simon Laplace - 1776 An intelligence
that knows all of the relations of the entities
of the universe at one instant could state
their positions, motions, and general effects any
instant in the past of future.
Henri Poincare 1903 Small differences in the
initial conditions can produce very great ones
in the final phenomena prediction Then becomes
impossible (1st recognition of chaos).
Werner Heisenberg 1924 There is a fundamental
limit on the accuracy to which position and
velocity can be co-determined.
Stephen Hawking 1988 In the cosmology of the
Big Bang and Black Holes, space and time
themselves break down.
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Position Probability Density Dwell Time
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Why didnt Isaac Newton think about the
possibility of getting hit on the head when he
sat under the apple tree?
? ?x ?
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Where does the pendulum spend the most time? The
least time?
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Dwell time
Time exposure
High many / slow
Low Few / fast
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Equal time inside No time outside
Most time at end points Least time at center
Most time at aphelion and perihelion
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The secret of life, computers, transitors
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1-D Periodic Motion
Non-relativistic conservative potential
Periodic motion with turning points
Distribution (xm? x ? xm)

Box
SHO
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So in general
Where V(x) can be any algebraic or numerical
function.
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Solve Numerically First normalize
Then evaluate
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Einstein-Brillouin-Keller Action Quantization
(1917) (1926) (1958)
Bohr-Sommerfeld-Wilson quantization used fuzzy
math, neglecting caustics at turning points in
librations. The correct semiclassical action
quantization condition is
where
?i 0 (rotations) 1 (tunnelling)
Topological Maslov Index
2 (librations) 4 (square well)
It yields astonishingly accurate results !!!
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Average Values of Powers of the Coordinate
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