Physics is

1
Physics is

• Physicists love to insist that ALL other sciences
  are built upon the foundational knowledge of
  physics.
• It used to be called Natural Philosophy which
  was the study of unanswered questions about
  nature.
• Since Physics studies Motion, forces, energy,
  matter, heat, light, sound, and elemental atomic
  particles it really does seem to be fundamental.
• Consider all the branches of science that you
  knowdoes each one begin its study with the
  principles studied in physics? Your text book is
  a pretty good outline of the entire field called
  physics. IF you can argue that the claim of
  physicists is unfounded, do so in a very specific
  essay for 20 EC pointsI will be amazed if you
  can do that.

2
Physics defined

• Generally, a good working definition of physics
  is the study of the way the universe works.
• A good definition of Chemistry would be the study
  of the way matter is put together.
• For 20 points, please choose 10 other branches of
  science and define the general purpose of each of
  those sciences. DUE____________

3
Out of the fog

• In the 16th C, science made a great leap forward
  out of the realm of whim, superstition, myth and
  into the measurable predictable explanatory realm
  of math and measurement and experiment.
• In 16th C it was discovered that Nature could be
  analyzed, predicted, measured. It was
  unambiguous. Its language was math. Its proof was
  experiment.
• In fact, we say that math and experimentation are
  the twin pillars of sciencethe search for
  knowledge.

4
Those words.

• We use a lot of words in sciencewe better come
  to some agreement as to their meaning so we can
  communicate with one another.
• A FACT I wonder if we went around the room what
  definitions we might get.
• Let us agree that a fact is a close agreement by
  trained observers of observations made of the
  same phenomena.
• A HYPOTHESIS we shall agree is an educated guess,
  a presumed fact until tested by experimentation.
  If it is tested often and not contradicted, a
  hypothesis tends to slide toward a law or
  principle. It is an accepted fact until
  contradicted by evidence. In science ONE
  verifiable, contradictory experiment outweighs
  ANY authority regardless of reputation.
• Science distinguishes between what is seen,
  measurable, factual, tested vs what we WISH to
  see, to believe is true.

5
The Urban Legends

• Most widespread assumptions are the least
  questioned
• For a long time, the notion was passed around
  that one could see the great wall of china from
  the moonnot so
• Alligators live in NYC sewers
• It is a law that you must pull over for an
  ambulance with lights and sirens going
• Heavy things fall faster than lighter things

6
Its only a theory..

• Guess what?
• A theory is a very powerful statement!
• What most people MEAN to say when they misspeak
  is its only a hypothesis.
• A THEORY in fact is a very large body of
  information that has been WELL tested and
  verified often, over and over without
  contradiction to date
• Theories include the theory that everything is
  made of atoms or parts of atoms.sort of the
  basis of chemistry!
• Theories include the cell theory which you
  studied extensively in biology
• Soif someone says such a thingyou might want
  towalk away..

7
Theories

• Even though theories are strongly supported, they
  remain open to change.
• The theory of the atom has been refined over the
  years, starting with the likes of Democritus and
  Dalton right up to the cloud models we use today.
• The cell theory continues to be refined as we
  learn more and more about the functioning of the
  parts of every cell.

8
In science

• A hypothesis is sort of the start point of the
  scientific method. You have a question, there is
  no published answer and so you draw your own
  conclusion as to cause and effect. That is a
  hypothesis when you say I think the cause is
  or I bet this will happen when I do that
• So you test it. Are you right or wrong? Prove it?
• There is a cardinal rule here about the
  hypothesis
• In science your hypothesis MUST have a means of
  proving it WRONG not just right.
• If there is no test possible for wrongness then
  it is not a scientific hypothesis and thus
  nothing more than a wild guess.
• Remember when you learned about the word
  hypothesis your teachers told you it was an
  educated guessthat is what they meant by that.
  There MUST be a way to test the wrongness of the
  guess.

9
Here is an example

• Hypothesis?
• Intelligent life exists on other planets
  somewhere in the universe.
• This is NOT scientific. It is only speculation.
• The cardinal rule is broken. It is not possible
  to prove the hypothesis WRONG. Can only prove it
  if correct.
• If we find life then indeed it is correct.
• BUT
• If we examine lots of planets and we find no life
  on any of them it does not PROVE that life does
  NOT exist somewhere in the universe.
• If a hypothesis can be proven right but cannot be
  proven wrong then is not considered scientific.

10
What about these?

• Hypothesis
• A. Atoms are the smallest particles that exist
• B. The universe is surrounded by a second
  universe which cannot be detected by any
  scientific instruments or scientists.
• C. Albert Einstein is the greatest physicist
  since Newton.

11
And the answers are.

• A. Can be proven wrongand indeed has been
• B. No test possible for wrongness
• C. This is an assertion, an opinion, not testable
  by any objective means. No criteria possible to
  test for wrongness.

12
Physics is all about Matter, Space and Time.

• Our study of matter includes observing and
  measuring matters interactions and changes.
• We have NOT been very successful in studying or
  even defining space and time.
• Can you clearly define spacetime??
• We can discuss matter in terms of its mass,
  charge, momentum, energy content and change, its
  behavior given conditions of heat and pressure.
• We use space and time to describe the location of
  matter in space-time. This involves displacement,
  velocity, acceleration.

13
Sometimes we measure without knowing

• We must agree to communicate. Man is always
  trying to bring order into or out of the
  universe.
• All measurements are just agreements. Just like
  all language is just an agreement among peoples.
• So even if we cannot define concepts, we can use
  operational definitions like measurements.
• Example 1 second.
• Does it exist in nature? We have agreed to this
  thing called a second.
• We also have agreed that 1 second is the time it
  takes for A cesium 133 isotope to vibrate
  9,192,631,770 times.

14
There are rules

• To study physics requires belief that there are
  rules in the universe, nature plays by those
  rules and we can know those rules.
• The language of science is math.
• Physics quantifies. It translates concepts into
  equations, numbers, measurements.
• Physics seeks to understand via observation,
  objective collection of datathat is finding out
  how much, how big, how fast, how many etc.
• Physics is a search for patterns in nature,
  relationships.
• We look for natures truths, the laws which are
  descriptions of relationships that DO exist in
  nature.

15
More historical notes

• Until the 1920s there was what might be called
  classical physics. It rested on 3 pillars of
  understanding
• Newtonian mechanicswhich is the bulk of this
  course
• The electromagnetic theory and
• Thermodynamics.

16
And more

• It was Einstein who revolted against the God
  Newton just as Newton had revolted against the
  God Aristotle.
• Einstein wrote the Special Theory of Relativity
  in 1905
• His General Theory of Relativity written later
  completed the revolution of thinking which led to
  
• Space-Time motion
• Curved space-time
• Black Holes
• Pulsars
• The Big Bang

17
Was Newton wrong????

• Newton was not so much wrong as he was simply
  limited.
• Newtonian mechanics works very well at the
  everyday, macroscopic level.
• It was Newtonian mechanics that got us to the
  Moon, got probes to Venus, Jupiter,Mars and
  beyond our solar system.
• It is Newtonian mechanics that allows me to
  predict that if I let go of a ball it will fall.
• If I exert an unbalanced force on an object it
  will accelerate.
• If I let a book sit on the desk, it WILL stay
  there until some net force acts on it.
• It is Newton who told us that Nature is totally
  predictable,

18
Modern Physics is a little startling

• Although Newtons laws work very well at the
  macroscopic level, it turns out that at the
  subatomic levelinside the atom itselfthings we
  thought were predictable become a little less so.
• It turns out that inside the atom nothing is as
  it seems. Processes may appear to be continuous
  but they are not. Light appears to be continuous
  but it turns out you are being pelted with
  little, discrete, packets of energy called
  photons.
• It turns out that in Modern Physics there is no
  such thing as empty space since we now consider
  light to have some of the properties of matter.
• You, in fact, are packaged energya collection of
  photons.
• Modern physics says that forces are actually the
  absorption and emission of photons and the forces
  are the recoils from either of those two actions.

19
Today we continue to organize and make sense of
nature

• Today we say there are only really 4 forces that
  act in the universe as agents of change.
• Gravity
• Electromagnetism
• Strong force
• Weak force

20
It may surprise you to learn

• Gravity is by far the weakest of the 4 forces.
• It acts between EVERY particle
• It is ONLY attractive
• It has an infinite range
• Indeed, though it is weak, its range is infinity
  so we can say
• GRAVITY RULES

21
Electromagnetism

• This force binds together atoms, molecules,
  trees, buildings, YOU!
• EM forces are responsible for all contact
  forcespushes and pulls, a fist hitting a
  punching bag, teeth cutting through a hamburger.
• EM generates FRICTION!
• This force creates drag, adhesion, cohesion.
• EM is responsible for elasticity and it governs
  all of chemistry.
• It rules life and death.
• And it keeps the Earth and everything riding on
  the Earth from being crushed by gravity. Gravity
  is not strong enough to overcome repulsive and /
  or attractive electrical forces.
• The EM forces are either attractive or repulsive.
  The range is infinite but the attractive/repulsive
  possibilities limits its effective range.

22
And the other two??

• The strong and weak forces are found within the
  atom. They tend to be beyond the scope of this
  course and are more generally taught in advanced
  chemistry courses.
• It will be a challenge enough for us to come to
  some understanding of the other two.