Introduction to physics
• The Feynman Lectures on Physics Vol. I, II, III
• http://www.feynmanlectures.info/
Schedule
• 4 hrs lectures every week, mainly following
Feynman but also some other references: 赵凯华，
新概念物理教程
• 2 hrs recitations (辅导）
• + labs
• Homework
• Language: both English and Chinese (双语），will
use Chinese but encourage English
Rules of lectures
• Don’t be late：A piece of paper keeping record
• Don’t play with cell-phone, read other books
• Don’t talk to each other
• Don’t eat and drink
• Don’t sleep
•…
Lecture1：
What is physics?
First lecture
• The goal of physics is to find the simple principle (rules of
game) behind complicated phenomena. (Reductionist)
• Approach: observe (measurement), model (explanation),
model (prediction), verification (observe again): Scientific
method
• Model, approximation, use of math
• Observation, invention of instruments (Nobel prize)
• Reductionist approach (Amalgamate),
• emergent phenomena, human life
• Physics knowledge is useful
• Scientific method is useful
• limitations
Goal of physics
• Find the simplest principle (rules of game) behind
complicated phenomena. (Reductionist!)
• Real world is very complicated, all sorts of
phenomena
• Light, Color, motion, people, clouds, water flow, bird fly,
stars, winds, rain...
• Analogy: watching chess games…. There are a few
simple rules governing the games: secrets of
nature!
• Physicists want to find the secrets of nature!
Very useful skills
• Detectives！
• 007 (James Bond)!
• In fact, if you want to do anything well in life, you
need to find the simple rules behind phenomena,
such as complicated human relationships:
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Be courteous to others, do not offend people
Listen carefully, do good investigation
Be responsible
Care about others
• Physicists are in hot demand!
Reduction vs. emergent
phenomena
• If you just know a bunch of rules about chess
games, you may not be a good chess player.
• Just to find the secrets? well, some call these
people reductionist.
• One shall also learn to build beautiful things out of
the simple rules (art, human being)
• A pretty talking girl is not just a collection of atoms,
molecules and cells…
• Is emergent phenomenon fundamental? Some
argue “of course”
How do we find rules: scientific
methods
• Observe (measurements), eyes, instrumentations,
inventing new instruments, an extremely important
part of physics! (experimental physicists)
• Imagination (smart), approximation (art), models,
explanations, here math is very useful. We will talk
about more about math later. (theorists)
• Prediction (model or theory must be falsifiable.),
without prediction, the model is essential useless.
(theorists)
• Verification: observe or experiment again.
(experimenters)
Measurements
• Tools: money (rich)+invention, time (human resources)
• Inventing instruments
• 70% of Nobel prize is related to invention of
instruments for measurements. See what people have
not seen before!
• Not many Chinese students are interested in expt., not
a good phenomena. (no money before, but…)
• Experimental physics is directly related to new
technology!
• China needs more experimenters, more technology to
become a real world leader (not just money!)
Theorists and computation
• Making models needs math, one learns a lot of
math: Calculus, more complicated ones: geometry,
algebra, applied math… lot of tricks
• A lot of math tools were developed for physics
problems (differential and algebraic geometry).
• Another important tool is computer! Computer
simulations become indispensable. China has the
largest computer in the world. But computational
physics is not very advanced. I hope there are more
people devoted to computational physics.
What physics studies
• Matter (gas, liquid, solid) and their motion and
microscopic structure
• Mechanics (motion and force)
• Electricity and magnetism (force)
• Laws of physics at many distance scales, very small
one to very large one: such as the scale of the
universe
• One of the most important area is the microscopic
structure of matter (20th century)
Physics is very useful!
• The knowledge we obtained from physics has
changed our lives forever!
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Mechanics: cars, buildings, bridges
Electromagnetism: phone, bulbs, computer, information,
Heat: air-condition, refrigerator, energy sources
Atoms: new materials, medicine, energy sources,
quantum computers
• However, the original goal of studying physics is not
meant to be useful. It meant to understand how
nature works, curiosity driven research… Highenergy physics internet!
Scientific method is useful
Physics method is the origin of scientific method
which now has wide use!
• Engineering
• Astronomy
• Chemistry, biology
• Computer
• Social sciences
• Money market
• Medicine
• Archeology
• ….
Limitations of the scientific
method
• If you cannot measure or see, science cannot tell
you anything.
• One can speculate, or believe in something which
cannot be verified. That is called religion, or ideal!
• Science cannot tell you everything about life, for
example, philosophy
• Science is not a substitute for everything, for
example, love.
• Science can be a way of life!