Transcript Lecture 00 - TTU Physics

Welcome to Physics 5305
Statistical Physics!
Brief Overview of the
Structure of Physics
• Where does Statistical Physics fit in
to the overall organization
(structure) of Physics?
• What about Thermodynamics?
• How is Thermodynamics related
to Statistical Physics?
Occasionally, I’ll make comments on Physics
History, Famous Physicists & Physics
Trivia (interesting to me!)
Niels Bohr
1922 Nobel Prize
in Physics for
“His services in the
investigation of the
structure of atoms &
of the radiation
emanating from them.”
Interesting Trivia (to me)!
Niels Bohr is the only Nobel Prize Winner
to have ALSO been an Olympic Medalist!
In the 1908 Olympics, he
& his brother Harald*
were on the Danish soccer
team, which won a sliver
medal!
*Harald Bohr later became
a famous mathematician!
Interesting Trivia (to me)!
Neils Bohr’s son, Aage Bohr also received a
Nobel Prize in Physics!
He shared the 1975 Nobel Prize
with B. Mottelson & J. Rainwater
“for the discovery of the
connection between collective
motion & particle motion
in atomic nuclei & the
development of the theory of the
structure of the atomic nucleus
based on this connection”.
Overview of
The Structure of Physics:
Where do
Statistical &Thermal Physics
fit in to the structure &
organization?
The Structure of Physics
Classical Physics is The Foundation
of pure & applied (macroscopic) physics & engineering!
Newton’s Laws + Electromagnetism
+ Statistical Mechanics + Thermodynamics.
(The Latter Topics are what this course is about!)
These together give a good description of most of the macroscopic world.
Classical Mechanics
(Newton, Lagrange, Hamilton,..)
The Physics of the 17th & 18th Centuries.
Still useful in the 21st Century!!
Physics Structure
Classical Electromagnetism & Optics
(Newton, Coulomb, Gauss, Ampere,
Faraday, Maxwell,..)
The Physics of the 18th & 19th centuries.
Still useful in the 21st Century!
High Speeds (v ≤ ~ c) 
Special (& General) Relativity
(Einstein, ..) 20th Century Physics!
Physics Structure
Small Size (atomic & smaller):
Quantum Mechanics
(Bohr, Schrödinger, Heisenberg….)
20th century physics!
Relativity + Quantum Mechanics:
Relativistic Quantum Mechanics
(Dirac,…) 20th century physics!
Quantum Field Theory
(Feynman, Schwinger, ..) 20th century physics!
“Mechanics”
• HOW objects move (behave) under given forces.
• (Usually) Does not deal with the sources of forces.
Answers the question:
Given the forces, how do objects move?
• Forces in the universe are classified into 4 types:
The 4 Fundamental
Forces Of Nature!
Some version of Mechanics
applies to all four!
The 4 Fundamental Forces of Nature
The sources of the forces, in order of decreasing strength
The Strong Nuclear Force:
Binds nuclei together. Explained by the “Standard Model”
& Quantum Chromodynamics. Still being researched.
The Electromagnetic Force:
E&M phenomena. Chemical forces. Most everyday
forces. Maxwell, Coulomb, Ampere, Faraday, ...
The Weak Nuclear Force:
Nuclear decay. Fermi, Bethe, others. Electroweak Theory.
The Gravitational Force:
Newton (classical mechanics),
Einstein (general relativity), Hawking….
The 4 Fundamental Forces of Nature
The sources of the forces,
in order of decreasing strength
The Four Fundamental Forces
The “Electro-Weak” Force
Since ~ the late 1960’s, in some sense,
the 4 fundamental forces
have been reduced to three!
The Electromagnetic Force & the Weak
Nuclear Force were combined into one
theory. This was done by S. Weinberg & A.
Salaam. For this work, they received the
1972 Nobel Prize in Physics!
The Standard Model of Particle Physics
“Periodic Table for Elementary
Particles”! Quantum Chromodynamics
(QCD) & the Electroweak Theory
Protons & Neutrons consist of 3 Quarks each.
The Standard Model
The Standard
Model
The Standard Model
SUMMARY: THE STRUCTURE OF PHYSICS
Low Speed
High Speed
v << c
v<~c
Large size
Classical Mechanics
Special Relativity
>> atomic size (Newton, Hamilton,
(Einstein)
Lagrange)
Small size Quantum Mechanics
< ~ atomic size
(Schrodinger,
Heisenberg)
Atomic Physics
Molecular
Physics
Solid State
Physics
Nuclear & Particle Physics
Relativistic Quantum
Mechanics
(Dirac)
Quantum Field Theory
(Feynman, Schwinger)
Quantum Electrodynamics
(Photons, Weak Nuclear Force)
Quantum Chromodynamics
(Gluons, Quarks, Leptons
Strong Nuclear Force)
The Rest of Physics!
• What we’ve mentioned so far is  all of physics except:
Statistical Mechanics:
(This course ≡ “Stat Mech” )
“Stat Mech” is the mechanics of systems of
huge numbers (>> ~ 1023) of particles.
Stat Mech:
1. Uses Probability & Statistics to calculate macroscopic
properties from microscopic force laws.
2. Applies to BOTH the Classical & the Quantum worlds!
3. Is the major link between microscopic & macroscopic physics!
4. Contains Thermodynamics as a sub-theory!