Physics 20
Introduction to Physics
What is Physics?
• a branch of Science
• What are some other branches we
know?
• Chemistry, Geology, Biology,
Astronomy, Environmental Science,
Social Sciences…..
What is Physics?
• Physics comes from the Greek word
“Physis” which means “nature”
• So is Physics the Science of Nature?
• Wait a sec! What is Biology?
• Bios-life
• logos- the study of.
• So biology is the Science of Life.
• If we use the word “nature” to refer to
the whole external universe, then we are
getting close.
What is Physics?
• It is the science of matter, it’s
motion, as well as space and time.
• Physics can be thought of as
humanity’s attempts to describe and
explain our universe.
What is Physics?
• Physics has many different branches within
it:
•
http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html
• Some of the topics commonly
covered in Physics 20 :
Waves, Light, and Heat
Physics 30: Kinematics and Dynamics,
Electricity, Mechanical Energy, Nuclear
Physics
What is Physics?
• Is this all of Physics?
• Not by a long shot! But all of the
topics that we discuss here are
relevant and used everyday by
researchers!
What is Physics?
• One interesting way to look at Physics is
the scale which it encompasses.
• Physicists are concerned with the most
elementary of particles that make up
matter in the quantum realm; the pieces
that make up atoms!
• They are also concerned with the stars and
other heavenly bodies that are amazingly
large and far, far away.
What is Physics?
• Here we have a number of galaxies,
each contains somewhere between
ten million and one trillion stars.
• The universe itself is estimated to
have 9 × 1021 stars (9 billion trillion
stars)
What is Physics?
• When we really start to look for
Physics, we can find that it is
everywhere!
• Medicine, Cell-phones, cars, TV’s,
sports, that’s right sports! (think of
the “sweet spot” on a bat, that’s
Physics)
Is Physics only for
Physicists?
• A Physics education is a key to
understanding science, and can only help to
open doors for the future.
• The lines between Physics and other
science areas like Biology become blurred
in many areas of study. For example
Medical Physicists and Ultrasound
Technichians have a great amount of
knowledge of both Biology and Physics
(they also make lots of money).
• The point is, many of the disciplines of
science (if not all) are interrelated.
The Nature of Science
• Physics relies upon empiricism.
• Empiricism: the practice of relying on
observation and experiment especially in
the natural sciences.
• In Science, we make observations, and
from these observations questions are
often raised.
• These questions can lead to
experimentation with more observations,
which can then lead to more questions. It’s
an ongoing cycle!!
Where Did Physics Start?
(by no means is this complete)
• Since Astronomy is a sub-field of Physics, we can
say that our earliest records of Physics come from
Babylonia (modern day Iraq) around 2000 B.C.
Here astronomers looked up and recorded what
they saw on stone tablets.
• Later came the Greeks.
• 384 B.C. Aristotle tried to write laws which
governed the motion of objects. Although they
were wrong, they were an attempt. He also
believed in a geocentric universe.
•
Where Did Physics Start?
Where Did Physics Start?
• Nicolaus Copernicus receives his copy of his book
“De Revolutionibus Orbium Coelestium” (On the
Revolutions of the Celestial Spheres) on his death
bed.
• It set forth the notion that the Earth rotates
around the sun. (Heliocentric model). Note that
he wasn’t the first to suggest this, he was just the
first person that anyone listened to.
• His book sparked the Scientific Revolution, a
great leap forward in scientific discoveries and
theories.
Where Did Physics Start?
Where Did Physics Start?
• Galileo “The Father of Modern Physics”
• Creates the telescope to further support the
heliocentric model.
• Threw things off of the Leaning Tower of Pisa to
show that all things accelerate downwards at the
same rate regardless of their mass.
• In trouble with the church who supported the
geocentric model.
Where Did Physics Start?
Where Did Physics Start?
Where Did Physics Start?
• Sir Isaac Newton
• Widely regarded as the most influential scientist
of all time.
• Three laws governing motion (Physics 30) which
are the groundwork for classical mechanics.
• Developed a theory of colour when he noticed that
white sunlight could be split into spectra using a
prism
• Mathematical genius, he created calculus (at the
same time as someone else Leibniz)
• Jerk, often people would be working on things that
he had discovered earlier and he refused to share.
• He also developed the milled-edge coin to prevent
counterfeiting.
• What do you think of when you think of Newton?
Where Did Physics Start?
Where did physics start?
• Marie Curie was a physicist and
chemist
• she was a pioneer in the field of
radioactivity,
• the only person honoured with Nobel
Prizes in two different sciences
• the first female professor at the
University of Paris.
Where Did Physics Start?
• Am I missing someone?
• Who is the most famous scientist of all
time?
• I will give you a hint, Time magazine
declared him the person of the century in
1999
Where Did Physics Start?
• Albert Einstein (1879-1955)
• The “Miracle Year” of Physics occurred in 1905
when Einstein published four papers.
• His paper on Special Relativity gave us some
amazing implications for mechanics, For example,
now we knew that moving clocks (very fast)
actually registered a slower passage of time.
• Finally, Einstein gave us the famous equation
E=mc2 which tells us that mass and energy are
equivalent.
Where Did Physics Start?
Genius
Is Physics Done?
• No! There are still many, many questions
that we don’t know the answer to. Some
people argue if Physics will ever be
complete.
• Perhaps the greatest goal of Physics is a
“Theory of Everything”, a single set of
equations that describe all the forces and
matter in the universe.
• It hasn’t been easy; we’ve been looking for
over 150 years!!
So What Can You Do As a
Future Physicist?
• Ask questions!
• Try new things!
• Try to remember the questions you
wanted the answer to when you were
a child, “Why is the sky blue?”,
“Where do people come from” (note,
I’m talking about the human race) etc.