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 HeatPhysics 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.

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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.