Welcome to PHYS 201Modern Physics
Fall 2017
Meeting times:MWF 10:00-10:50am; F 2:00-2:50pm
Co-requisite PHYS 251Experimental Atomic Physics
Textbook
Required text:Modern Physics by R. A. Serway, C. J. Moses, C. A. Moyer,
Possibly useful math resource:M. L. Boas, Mathematical Methods in the Physical Sciences, 3rd Ed.
Necessary background
Prerequisites: This course assumes a solid background in first year physics and math.- Full year of calculus-based general physics PHYS
101-102. Algebra-based general physics courses PHYS 107-108 are less optimal . AP Physics is not usually sufficient.
- Full year of calculus at the level of Math 111-112 (and here AP credit is sufficient).
This is a fast-passed and challenging course. Judge your preparedness before you dive in!
Grading
Past years grade assignment
25%30%
20% 20%
A 92 B- 74
A- 87 C+ 69
B+ 84 C 64
B 79 C- 59
This assignment
is likely to be adjusted
for the test scores.
There will be extra credit opportunities!
Homeworks
12 assignments, due beginning of the corresponding Friday class.
Late assignments will be accepted with a 50% penalty when submitted on or before Monday class following the due date.
Any assignment turned in after that time will not be accepted (unless you obtained a permission form me beforehand).
http://www.physics.wm.edu/~inovikova/phys201/CourseSchedule.htm
Homeworks
Comments/responses :“Modern Physics” is a COLL200course, reaching out into CSI(Cultures, Societies, and Individuals).There will be weekly readingassignments regarding the historicalsignificance of the events discussedin class.After each discussion, you shouldread these essays and write roughly½ page of thoughts, comments, andquestions about the material.
http://www.physics.wm.edu/~inovikova/phys201/CourseSchedule.htm
My contact information
Office : Small 251E-mail : ixnovi[at]wm.edu or inovikova[at]physics.wm.eduOffice hours : Wednesday 11am – 12pm; Thursday 1-2pmWeb-site : http://physics.wm.edu/~inovikova/phys201/phys201.htm or in Blackboard
Area of research: experimental atomic physics and quantum opticsResearch projects: quantum memory and slow light, miniature atomic clocks, “squeezed” light, optical microresonators, optical properties of thin films, etc.Lab location: Small 65, 34 (basement)Web-site: http://physics.wm.edu/~inovikova/group.html
Birth year of modern physics - 1895
Telephones
Automobiles
Industry (steam engine-driven)Electricity
And now back to physics!
The more important fundamental laws and facts of physical science have all been discovered that the possibility of their ever being supplanted in consequence of new discoveries is exceedingly remote… Our future discoveries must be looked for in the sixths place of decimals.
There is nothing new to be discovered in physics now. All that remains is more and more precise measurements.
Lord Kelvin, 1900
A. A. Michelson, 1900
“Classical” physics – XIX century
√ Mechanics
√ Electromagnetism
√ Thermodynamics
√ Optics
Log (size)
Spe
ed
0
c
19th-century physics
Gen
eral
rel
ativ
ity
Qua
ntum
mec
hani
cs Special relativity
“Classical” physics – XIX century
XX century – “Modern” physics√ Special and general relativity
√ Quantum mechanics
√Atomic and molecular physics
√ Nuclear and particle physics
√ Mechanics
√ Electromagnetism
√ Thermodynamics
√ Optics
“Classical” physics: Conservation laws
• Conservation of energy : The sum of energy (in all its forms) is conserved (does not change) in all interactions.
• Conservation of linear momentum : In the absence of external forces, linear momentum is conserved in all interactions.
• Conservation of angular momentum : In the absence of external torque, angular momentum is conserved in all interactions.
• Conservation of charge : Electric charge is conserved in all interactions.
“Classical” physics: Mechanics
Newton’s first law:
An object in motion with a constant velocity will continue in motion unless acted upon in some net external force.
Newton’s second law:
Newton’s third law:
( )dt
vmdamF
rrr
==
2112 FFrr
−=
“Classical” physics: Mechanics
Galilean transformation:
Relates the time and space coordinates between two inertial systems in relative motion.
“Classical” physics: Mechanics
Galilean transformation:
Relates the time and space coordinates between two inertial systems in relative motion.
“Classical” physics: Electromagnetism
Gauss’s law (electricity)
Gauss’s law (magnetism)
Faraday’s law
Ampere’s law
2
0
10
BE E
t
EB B
c t
∂∂∂∂
∇ ⋅ = ∇× = −
∇ ⋅ = ∇× =
rr r r r
rr r r r
Differential form in vacuum
“Classical” physics: Electromagnetism
22
2 2
10
EE
c t
∂∂
∇ − =r
r
Wave equation solution:
Maxwell’s equations simplify to the wave equation for the electric (and magnetic) fields:
( , ) cos( )E r t t k rω∝ ± ⋅rr r r
/c kω=r
which has a simple sine-wave solution:
“Classical” physics: Wave optics…but what’s waving???
A wave needs a medium to propagate -“ether” or “aether.” Light waves were found to be solutions to Maxwell’s Equations, showing that light is electromagnetic wave, propagating at the speed c:
But in what reference frame?
Another problem with Maxwell equations – their form changes under Galilean transformation!
“Classical” physics: Thermodynamics
First law of thermodynamics:
The change in the internal energy ∆U of a system is equal of the heat Q added ti the system plus the work Wdone on the system.
∆U = Q + W
Second law of thermodynamics :
It is impossible to convert heat completely into work without some other change taking place.
Ideal gas equations:
PV=nkBT
Ultraviolet catastrophe
As an object gets hot, it radiates energy. Black body absorbs and emits radiation on all frequencies. An ideal blackbody radiator can beconsidered as a black box with a tiny hole.
Classical thermodynamics failed to explain the spectrum of the blackbody radiation.
Birth of “modern” physics
In a speech to the Royal Institution in 1900, Lord Kelvin himself described two “dark clouds on the horizon ” of physics:
The question of the existence of an electro-magnetic medium—referred to as “ether” or “aether.”
The failure of classical physics to explain blackbody radiation.
Special relativity
Quantum mechanics
Birth of modern physics (cont)
• Discovery of the X-rays (Roentgen, 1895)• Discovery of Radioactivity (Becquerel, 1896)
• Discovery of the electron (Thomson, 1896)• Discovery of the Zeeman effect - splitting of atomic
spectral lines in magnetic field (Zeeman, 1897)
Nuclear physics
Quantum mechanics, atomic physics
• Special relativity• Basics of quantum mechanics• Introduction to atomic physics and
spectroscopy• Briefly: molecules, solid state physics,
semiconductors, nuclear and particle physics
What we are going to do this semester…
• The effects we are going to discuss are outside of our everyday experiences.
• We have no intuition to guide us!• The correct solution may seem as weird
as any incorrect one.
Why it is challenging?