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Welcome to
Physics 43!
Classical Mechanics!
Study of the motion of objects and
mechanical systems that are large
relative to atoms and move at speeds
much slower than the speed of light.
You can’t get to Modern Physics
without doing Classical Physics!
The fundamental laws and
principles of Classical Physics
are the basis Modern Physics.
Some
Physical Models
of the Universe
A Brief History
of Physics
Physics seeks a single theory of
Everything….and it always has…
Bubble Universes
Superstrings
Theory of Everything (TOE)
History is IMPORTANT
The historical development of science shows us the
process of discovery and the way our brains work
and POSSIBLY the inherent biases and limitations
of the rational mind. By studying the historical
development of science we learn about the
mistakes that have been made so hopefully we do
not repeat them...and maybe we discover old ideas
that still have something to teach us about the way
the universe works…or at least, how our brains
work…
Let no one unversed in geometry enter here.
The Universe is made of pure mathematical ideas – the Platonic
Solids. Plato believed that the stars, planets, Sun and Moon move
round the Earth in crystalline spheres.
Earth and the universe were seen as constructed out of five basic
elements: earth, water, air, fire, and ether. The natural place of the
motionless Earth was at the center of that universe. The stars in the
heavens were made up of an indestructible substance called ether
(aether) and were considered as eternal and unchanging. The laws of
nature of the Earth were different from those of the Heavens.
The Sun and the planets would
revolve in small circles whose
centers revolve in large circles about
the Earth ("epicycles") which is at
rest and at the center of the Universe.
From our perspective, the sun and stars appear
to orbit us!
Ptolemy's geocentric
system, adopted by
the Roman Catholic
Church, dominated
western thought until
the time of
Copernicus, 14
centuries later…..
th
th
5 -15
Centuries
Developed science & medicine
based on observation and
experiment, rather than on
conjecture creating the basis of
what would later be called
The Scientific Method.
European Enlightenment
Renaissance
14th & 15th Century
The Vitruvian Man 1490
Copernicus put the Sun at the center of the solar system with the Earth
orbiting around the Sun, thus proposing a heliocentric cosmology. Like
Aristotle and Ptolemy, Copernicus retained the conventional idea that
the planets moved in perfectly circular orbits and continued to believe
that the stars were fixed and unchanging.
REVOLUTION!
I hold that the Sun is located at the centre of the
revolutions of the heavenly orbs and does not change
place, and that the Earth rotates on itself and moves
around it.
Galileo Challenged The Dogma
Of Natural Motion with
Experiments
Heliocentric Heretics
Rome, Campo de'fiori: The monument to
Giordano Bruno, burnt at the stake here.
The Trial of Galileo
June 22, 1633: Galileo was convicted and sentenced to life
imprisonment by the Catholic Inquisition.
In 1992, the church finally lifted its edict of Inquisition against
Galileo, who went to his grave a devout Catholic, despite the
church’s treatment of him.
Based on observational data he derived three laws of
planetary motion that put the sun at he center of the
universe with elliptical orbits.
Kepler’s 3 Laws of
Planetary Motion
1: The orbit of each planet
about the sun is an ellipse
with the sun at one focus.
2. Each planet moves so that it sweeps
out equal areas in equal times.
3. The square of the orbital period
of any planet is proportional to the
cube of the semimajor axis of the
elliptical orbit.
T12
 constant
3
r1
Planet Orbits are Elliptical
"The next question was - what makes planets go
around the sun? At the time of Kepler some people
answered this problem by saying that there were
angels behind them beating their wings and pushing
the planets around an orbit. As you will see, the
answer is not very far from the truth. The only
difference is that the angels sit in a different direction
and their wings push inward."
-Richard Feynman
Isaac Newton
(1642 -1727)
Using his Calculus, Newton derives Kepler’s
three laws of planetary motion from his own
three laws of motion and his Universal Law of
Gravity. Newton is the man of the millennium.
In Principia (1687 ) Newton
•Invented Calculus
•3 Laws of Motion
•Universal Law of Gravity
Newton’s Principia in 1687.
Galilean Relativity
Space and Time are ABSOLUTE!
u= u‘+v
Velocities add:
Newton’s First Law
(Law of Inertia)
An object will remain at rest or in
a constant state of motion unless
acted upon by external net forces.
Newton’s 2nd Law
 F  ma
Fnet
a
m
The acceleration of object is directly
related to the net forces acting on it and
inversely proportional to its mass.
Newton’s 3rd Law
Fhand on wall   Fwall on hand
To every force there is an equal but
opposite reaction force.
Universal Law of Gravity
1687
Every particle in the Universe attracts every other particle with a
force along a line joining them. The force is directly proportional to
the product to their masses and inversely proportional to the square
of the distance between them.
d
m
mM
F~ 2
d
M
Conservation of Energy
Energy can neither be created nor destroyed.
It may change in form or be transferred from
one system to another.
The total amount of energy in the Universe
is constant and can never change.
Ei  E f
Except for VERY brief amounts of time according to the Heisenberg Uncertainty Principle.
Robert Hooke (1635-1703)
•Leading figure in Scientific Revolution
•Contemporary and arch enemy of Newton
•Hooke’s Law of elasticity
•Worked in Physics, Biology, Meteorology, Paleontology
•Devised compound microscope
•Coined the term “cell”
1800’s: Atomic Emission of Light
Each chemical element produces its own
unique set of spectral lines when it burns
Fraunhofer Lines: 1814
The English chemist William Hyde Wollaston was in 1802 the first
person to note the appearance of a number of dark features in the
solar spectrum. In 1814, Fraunhofer independently rediscovered the
lines and began a systematic study and careful measurement of the
wavelength of these features. In all, he mapped over 570 lines, and
designated the principal features with the letters A through K, and
weaker lines with other letters.
Kirkoff’s Rules for Spectra: 1859
German physicist who developed the spectroscope and the science of
emission spectroscopy with Bunsen.
Bunsen
Kirkoff
* Rule 1 : A hot and opaque solid, liquid or highly compressed gas emits a continuous spectrum.
* Rule 2 : A hot, transparent gas produces an emission spectrum with bright lines.
* Rule 3 : If a continuous spectrum passes through a gas at a lower temperature, the transparent
cooler gas generates dark absorption lines.
Anders Jonas Ångström 1869
Ångström measured the wavelengths on the
four visible lines of the hydrogen spectrum,
obtained with a diffraction grating, whose
dispersion is linear, and replaced
Kirchhoff's arbitrary scale by the
wavelengths, expressed in the metric
system, using a small unit (10-10 m) with
which his name was to be associated.
Line color
red
blue-green
violet
violet
Wavelength
6562.852 Å
4861.33 Å
4340.47 Å
4101.74 Å
Balmer Series: 1885
Johann Balmer found an empirical equation that correctly
predicted the four visible emission lines of hydrogen
Johannes Robert Rydberg generalized
it in 1888 for all transitions:
1
 1 1
 RH  2  2 
λ
2 n 
RH is the Rydberg constant
RH = 1.097 373 2 x 107 m-1
n is an integer, n = 3, 4, 5,…
The spectral lines correspond to
different values of n
Hα is red, λ = 656.3 nm
Hβ is green, λ = 486.1 nm
Hγ is blue, λ = 434.1 nm
Hδ is violet, λ = 410.2 nm
Why a discrete spectrum?
Why THIS spectrum?
Why this shape?
Why the drop?
Sadi Carnot: Father of Thermo
(1796 –1832)
1824: A heat engine
operating in an ideal,
reversible cycle (now
called a Carnot cycle)
between two reservoirs is
the most efficient engine
possible. This sets an
upper limit on the
efficiencies of all other
engines.
Kinetic Theory/Thermodynamics
• Gas Particles are in constant RANDOM motion
• Particles have different speeds
• Pressure : momentum transferred by particles colliding
• Average KE of each particle is ~ T
•Heat flows from hot to cold: Entropy
Young’s Double Slit:
Light is a Wave 1803
y bright
y dark
λL

m (m  0,  1,  2
d
)
λL 
1

 m   (m  0,  1,  2
d 
2
)
Oscillating Charges Produce
Radio Waves: 1887
Heinrich Hertz
“I do not think that the wireless
waves I have discovered will have
any practical application."
Frequency of EM wave is the same as the frequency of oscillation.
1896: Zeeman Effect
The Zeeman Effect is the splitting of spectral lines when a
magnetic field is applied.
photo Zeeman took of the effect named for him
Einstein visiting Pieter Zeeman in
Amsterdam, with his friend Ehrenfest.
(around 1920)
1860: E&M was Solved!
(Vector Form)
James Clerk Maxwell
1860s
Light is wave. The medium is the Ether.
c
1
0 o
 3.0 x108 m / s
Measure the Speed of the Ether Wind
The Luminiferous Aether was imagined by physicists since
Isaac Newton as the invisible "vapor" or "gas aether" filling
the universe and hence as the carrier of heat and light.
Michelson-Morely
Experiment
1887
The speed of light is independent of the motion and
is always c. The speed of the Ether wind is zero.
OR….
Lorentz Contraction
The apparatus shrinks by a factor :
1 v / c
2
2
A Problem with Electrodynamics
The force on a moving charge depends on the Frame.
Charge Rest Frame
(moving with charge)
F 0
Wire Rest Frame
(moving with wire)
F  qvB sin 
Einstein realized this inconsistency and could have chosen either:
•Keep Maxwell's Laws of Electromagnetism, and abandon Galileo's
Spacetime
•or, keep Galileo's Space-time, and abandon the Maxwell Laws.
On the Electrodynamics of Moving Bodies
1905
Time is Relative!
Space is Relative!
Only the SPEED
OF LIGHT is
Absolute!
Other Unsolved Mysteries of 1800’s
that gave birth to Modern Physics
•What is the ether?
•Is light particle or wave?
•What is matter made of?
•How and why do atoms radiate discrete
spectra?
•Are nebulae within our galaxy or are
they other galaxies?
•Is space & time finite? Infinite?
This is where our class begins….
Classical vs Modern
•Laws of Physics are deterministic.
•Space and time are absolute.
•Particles are Localized in Space and
have mass and momentum.
•Waves are non-localized in space and
do not have mass or momentum.
•Superposition: Two particles cannot
occupy the same space at the same
time! But Waves can! Waves add in
space and show interference.
•Laws of Physics are statistical.
•Space and time are relative.
•The speed of light is absolute.
•Particles are wave-like
•Waves are particle-like
Cosmic Quest(ions)
What is the Universe?
How did it come into existence?
What is Consciousness?
What is the fate of the Universe?
Is there a theory of everything?
Modern Physics:
Quantum & General Relativity
Albert Einstein
1916
Mass warps space-time.
The Field Equation:
Milky Way Galaxy
At the turn
of the 20th
century we
did not know
that there
were other
galaxies in
the
Universe!!!
Orbital Speed of Solar System: 220 km/s
Orbital Period: 225 Million Years
Cepheids
Hubble
V = Ho d
Observations made in 1922–1923 - the first to
support extra galactic galaxies, and the Big Bang.
Andromeda
Galaxy
Space and Time were created in
the Big Bang!
Evolution of Life in the Universe
Black Holes & Worm Holes
Gravity Waves
LISA
What is the World Made of? Atoms?
Atomic Theory
Super Strings: Particles are string
vibrations in resonance
Parallel Universes
Multiverse
The Universe is made of…
Regular Matter: 5%
Dark Matter: 25%
Dark Energy: 70%
Casimir Effect: Proof of the Zero
Point Energy of the Quantum
Vacuum
Dark Energy: The New Ether?
Accelerating the Universe toward
the Future
Future Evolution?
Quantum Entanglement
Quantum Computing
The Qubit
At the heart of the realm of quantum computation is the
qubit. The quantum bit, by analogy with the binary digit, the
bit, used by everyday computers, the qubit is the quantum
computer's unit of currency. Instead of being in a 1 or zero
state, a qubit can be in a superposition of both states.
Quantum Teleportation
Entangled photons are used to teleport other photons.
Quantum Encryption
Quantum Teleportation??
Quantum Quackery?
The Final Frontier: Consciousness
Each caged electron is a
qubit in a nanoscale
quantum dot. We have a
billion billion of them
enslaved by coherent near
electromagnetic brain fields
of low frequency . This
forms a mind-brain
hologram. There is direct
back-reaction of the
coherent phased array of
single electron dipoles on
their mental pilot landscape
field. This generates our
inner conscious
experience.
- Jack Sarfatti
A Quantum Model of
Consciousness
Leonard Mlodinow
Feb 9th!