Physics 249 introductory handout: Lecture 1, Sep 5th 2012
Reading: Chapter 3
Course:
Physics 249 Fall 2012: A Modern Introduction to Physics
MWF 9:55-10:45am
2223 Chamberlin Hall
Web site: 249 web site
http://www.physics.wisc.edu/undergrads/courses/fall2012/249/
Faculty:
Professor Matthew Herndon
Office Hours: Wednesdays 11-12
Office: 4279 Chamberlin Hall
Phone: (608) 262-8509 (office)
Email: herndon at hep.wisc.edu
Teaching Assistant:
Chien Seng
Office Hours: Wednesdays 2:25pm, Thursdays 4:35
Email: cseng at wisc.edu
Office: 5264 Chamberlin Hall
Text Book:
Modern Physics 6th Edition
Paul A. Tipler by Ralph Llewellyn
Link: Modern Physics
http://www.amazon.com/Modern-Physics-PaulTipler/dp/142925078X/ref=sr_1_11?s=books&ie=UTF8&qid=1345671086&sr=1-11
Web Site: Modern Physics 6e
http://bcs.whfreeman.com/tiplermodernphysics6e/
Lectures:
Covers concepts, derivation some example problems for complex topics.
Lecture notes handed out in class and available on the course web site after each lecture.
Homework:
Weekly homework except exam week. Homework due on Friday at the beginning
of lecture. Generally covers material from proceeding Wednesday, Friday, and Monday
lectures. First homework due Friday September 13th.
Discussion section and quizzes:
Discussion sections:
M 1:20-2:10pm, 2:25-3:15pm
2116 Chamberlin Hall
Quizzes:
Weekly quizzes given in discussion section except for exam week.
Exams:
Two in class midterm exams and a final exam will be given.
Midterm exams Friday Oct 12th and Friday Nov 16th
Final exam Friday Dec. 21st 10:05-12:05
Grading:
30% Homework
10% Discussion Quizzes
30% Midterm exams
30% Final Exam
Honors:
A 5 page (double spaced) term paper describing the work of a Nobel prize winner in
physics is required for Honors credit. The paper should summarize the award winning
work itself and present day research in the area including two recent papers from the
ArXiv as well as references to the original research papers that resulted in the prize. Due
Friday Dec. 7th. Please submit your paper by email in word or pdf format.
Syllabus topics.
1 Quantization of Charge Light and Energy
2 The Nuclear Atom
3 The Wavelike Properties of Particles
4 The Schrödinger Equation: 2 weeks
Midterm Exam 1
5 Atomic Physics: 2 weeks
6 Statistical Physics
7 Molecular Structure and Spectra
8 Nuclear Physics
Midterm exam 2
10 Review of Relativity
11 Particle physics: 3 weeks
The idea of particles as discrete entities with quantized charges seem obvious today to
anyone who has learned some basic physics. We understand that the atom is composed
of protons and neutrons in a compact nucleus with and orbiting electrons. We know that
the electrons have one unit of negative electric charge while the protons have one unit of
positive electric charge. The idea of discrete matter particles can be extended to photons,
which carry a quantized amount of energy.
However these ideas were revolutionary at the time and they bring up questions that
require an extensive introduction to modern physics to understand. Even today
fundamental questions that are brought up by the ideas of quantization as explained by
Quantum Mechanics are not understood.
An example of a question we have an answer to is why does the discrete or quantized
particle, the photon, exist. Though fully answering this question takes the full framework
of particle physics, which is based on a version of quantum mechanics that obeys
Einstein’s theory of relativity.
An example of a set of questions we don’t have an answer to is why the electron has the
exact value of electric charge that it has and why does the proton have an equal
magnitude but opposite charge. This question is actually made more difficult by particle
physics which has shown that the proton is made up of three particles called quarks with
charges -1/3e 2/3e and 2/3e.
In this class we will examine the experimental discoveries that led to the theory of
quantum mechanics. We will then solve the equations of quantum mechanics in order to
understand the physics of atoms and molecules. Finally we will expand the ideas of
quantum mechanics to include relativity and study nuclear and particle physics. This will
take us on a journey that starts with the paradigm shifts that fundamentally revised our
understanding of physics (Quantum Mechanics and Relativity) and takes us to the
forefront of modern research on those subjects.
We will go from the ideas of classical physics, which covered macroscopic and slow
moving physics, to Quantum Mechanics, which explains microscopic physics, relativity,
which explains physics near or at the speed of light, to particle physics, which explains
microscopic physics near or at the speed of light.
Understanding of physics in ~1850
1) Forces: We understood the ideas of forces as defined by Newton’s laws. Also we
understood the ideas of forces acting as a distance as in Newton’s theory of gravitation.
We didn’t understand why actions at a distance should take place.
2) Electricity and magnetism. We newly understood another force that acted at a
distance. Maxwell’s theory of electricity and magnetics as explained by Maxwell’s
equations. We didn’t understand the source of electric or magnetic fields.
1 and 2 covered much of the ideas we classify as classical physics.
3) Matter: We understood that matter probably made up of fundamental building blocks
typically called atoms (or molecules). Thus matter was discrete on the microscopic scale.
However, these discrete atoms had not been directly observed. Rather they were inferred
from evidence that gasses acted in a way consistent with being composed of discrete
small solid objects. Note that the study of thermodynamics and statistical phenomena
was key in understanding a fundamental property of microscopic matter. The exact
structure of these discrete atoms was not understood.
4) We understood that a solution of Maxwell’s equations existed in which oscillating
electric and magnetic fields could reinforce each other and travel through space at a
constant speed (the wave solution for light). Evidently no source need in this case.
We were already seeing hints of non classical physics but did not understand them yet.
Given these tools we had a framework to understand the results of some very surprising
experiments in a quantitative way and start to develop answers to the questions posed by
those results and what had been understood up to that point.