Transcript 14, The Modern World – we owe it to Physicsx

THE MODERN WORLD – WE
OWE IT TO PHYSICS
Michael Bass
Emeritus Professor
CREOL, The College of Optics and Photonics
University of Central Florida
MY DEBTS
Outstanding students:
At USC: M-J Soileau and S-T Wu
AT CREOL: Alexandra Rapaport and T-Y Chung
Outstanding Post-Docs/Colleagues:
At USC: Eric Van Stryland
At CREOL: Ying Chen and Scott Webster
And many others!
CREOL where I had the opportunity to do my research and to
explore my interest in the Culture and History of Science.
IN THE BEGINNING
God said let there be light – God was the first physicist and an optics person !!
Actually about 28,000 years ago someone made notches on a bone
counting the lunar months – he/she was keeping time.
4236 BC – Egyptian calendar showing that the star Sirius rose next to
the sun every 365 days.
1400 BC – first water clocks. This is critical break from measuring time by
astronomy to measuring it by a mechanical device.
~1550 AD Nicolas Copernig (Copernicus)
revises the calendar by assuming the earth
goes around the sun – starts a revolution.
WHERE AND HOW DID SCIENCE GET STARTED?
Near 600 BC Thales of Miletus suggested that things may follow consistent principles that
humans could figure out.
No myths or Gods were required, just human intelligence.
Pythagoras (580 to 490 BC) when he developed the Pythagorean theorem
relating the lengths of the sides of right triangles.
This simple mathematical formula is the first instance of theoretical
physics.
Logic- it was essential in a democracy (limited though it was)
such as Athens. Logical thinking was essential to scientific inquiry.
Euclid – plane geometry, conical sections, spherical
geometry and rigor in proofs.
Archimedes – levers, buoyancy and reflection of light.
In ancient Greece by some very bright thinkers!
ARISTOTLE’S COSMOLOGY – THE CELESTIAL ORBS
With the earth at the center, 8 spheres carried all else.
fixed stars
5 known planets
moon
sun
The earth was a sphere since that was the perfect shape.
With some
perturbations
known as epicycles
by Ptolemy this
worked quite well
for nearly 2000
years.
THE INDISPENSABLE INVENTION

THE PRINTING PRESS

1041-1048 CHINA

1234 KOREA

1450 GERMANY – JOHANNES GUTTENBERG

Invents a way to make moveable metal
type to enable affordable books and
widespread distribution.

Leads to the Protestant movement and
blossoming of science – puts ideas in the
hands of the people.
It was to the 15th century what the Internet is to the 21st.
THE JULIAN CALENDAR BASED ON ARISTOTLE’S
UNIVERSE WAS GETTING OUT OF SYNCH.
This would embarrass the church. So in 1514 the Pope asked Copernicus to look into
calendar reform.
Copernicus did and discovered that Aristotle was
wrong. The earth had to move around the sun.
This was heretical even if it was correct.
In 1543 he published his work “On the Revolution of
the Celestial Orbs” and 2 months later he died.
In 1582 the Gregorian (Copernican)
calendar was adopted .
His work was followed by Brahe, Kepler and
Galileo all showing that humankind was not at
the center of the universe. In fact the orbits
were not even circles.
Then came Newton!!
ISAAC NEWTON (1643-1727)
Together with Albert Einstein one of the two greatest scientists that ever lived.
Except for the time wasted trying to perform alchemy and find the
Philosopher’s Stone (~ 30 years) Newton was the
Lucasian Professor of Mathematics at Trinity College at Cambridge.
Invented Calculus (actually co-inventor with Liebnitz and a little with
DesCartes).
Laws of Motion.
Applied inverse square law of gravity to derive planetary orbits.
Invented the Newtonian telescope.
Showed that white light was made of light of different colors.
Observed Newton’s rings – an interference effect due to wave nature of
light.
Equally important was his demonstration of using fundamental principles to
solve physics problems.
This was the Newtonian synthesis. It was the critical tool needed to kick start
the modern world.
CONSERVATION LAWS AND THERMODYNAMICS
There was a quantity called temperature that had to
be defined to enable the discussion of heat.
Newton’s law – if there is no external force acting on a body the
quantity mass times velocity (momentum) does not change.
Total mass (today we say total mass-energy) is conserved.
After Nicholas Leonard Sadi Carnot in 1824 published
one of the most important papers in history others
realized that his most efficient engine was one in which
entropy did not change. In all others it must increase.
P
isoth.
adiab.
adiab.
isoth.
V
THE LAWS OF THERMODYNAMICS
0. YOU ARE ALLOWED TO PLAY - (THERE IS A QUANTITY CALLED TEMPERATURE.)
1. THE BEST YOU CAN DO IS BREAK EVEN – (MASS-ENERGY IS CONSERVED)
2. IF YOU PLAY LONG ENOUGH YOU ARE SURE TO LOSE – (IN A
CLOSED SYSTEM UNDERGOING A THERMODYNAMIC PROCESS THE
CHANGE IN ENTROPY CAN EITHER BE ZERO OR POSITIVE.)
THE INDUSTRIAL REVOLUTION –
SCORE 1 FOR PHYSICS
The ideas just mentioned enabled
inventors of
steam engines,
farm machines,
factory machines,
interchangeable parts,
food processing techniques,
transportation by ship and train,
improved water supply and sanitation,
the flush toilet and
advances in construction to flourish.
These to name a few.
THE IMPACT
Human population which from 1500 to 1700 had been pretty
constant at about 425 M grew to about 1 B by 1800.
There was:
Better housing,
cleaner water,
better sanitation,
clothing and
cleanliness (people used soap – probably the
most important medicine prior to antibiotics).
There were abuses – child labor,
slavery, unsafe working conditions
and so on but improved
transportation made it cheaper and
people could leave places where life
was harsh to try for something better.
They came to the Americas and
eventually this led to the United States.
THE ELECTROMAGNETIC REVOLUTION
During the industrial revolution another revolution was taking place.
The physics of it began way back in Greece when people rubbed one thing against the
other and found that they became attracted to each other.
2000 years later Coulomb, Franklin, and Biot and Savart, demonstrated critical properties
of electricity and magnetism.
The force laws
The properties of charges
MICHAEL FARADAY
Then in 1831, an uneducated bookbinder’s
assistant, Michael Faraday, performed incredibly
crucial experiments demonstrating that you
could turn mechanical motion into electric
current and vice-versa.
He had shown how to make an electric
generator and an electric motor.
He invented the concept of fields to describe his
results since he didn’t have the math skills.
Without Faraday there would be no
modern world.
MAXWELL, ELECTROMAGNETISM AND
ELECTROMAGNETIC WAVES
Without James Clerk Maxwell in 1861 at the age of 22 the
electromagnetic revolution would have taken much
longer to happen.
His famous equations describe electromagnetic fields that
result in electromagnetic waves that propagate at the
speed of light. These give access to the whole
q
E 
electromagnetic spectrum.

0
This is probably what god said.
B  0
E  
B
t
  B   0 J   0 0
Without Maxwell there would be no
modern world.
E
t
THE ELECTROMAGNETIC REVOLUTION
– SCORE 2 FOR PHYSICS
To the industrial revolution add
electricity to the factory and the home,
safer street lighting,
reduced fire risk,
telegraphy,
telephones,
radio,
television,
radar,
improved automotive electronics,
improved aircraft,
improved medical instrumentation and diagnostics, and
so much more including greatly improved optics and
spectroscopy.
THE IMPACT
In 1850 human population was about 1.2 B in 1950 it was 3.0 B.
Another huge impact of physics on the
modern world. Prior to this period
almost everyone was born, lived and
died within a 10 mile radius.
Transportation and mass manufacturing
made huge cities possible.
THE PROBLEM
The progress of science in the industrial revolution and the
electromagnetic revolution was put to use in WW I and WW
II and by some of the most evil dictators in history.
That is the problem. Scientists may do their work but
politicians, dictators and crackpots too often get to use it.
THE QUANTUM MECHANICS REVOLUTION
In the early 1900s there were Max Planck,
Neils Bohr and Albert Einstein who
quantized electromagnetic fields and
atoms, and showed that Bohr’s transitions
and Planck’s quantized energies led quite
naturally to the “black body” distribution
that Planck hypothesized.
There had to be something to quantum
mechanics!
IT GETS CURIOUSER AND CURIOUSER
Werner Heisenberg, Erwin Schrodinger, Wolfgang Pauli, Paul A. M.
Dirac and many others fleshed out the mathematics and
interpretations of this very strange subject.
All you could know is the likelihood of something happening. You had to
give up causality because in the quantum world, the world of the atom
and smaller, things were statistical. And most distressing was the
uncertainty principal:
iℏ∂Ψ/∂t=-(ℏ2/2m)∂2Ψ/∂x2+V(x)Ψ
px  h
SO WHAT DID QUANTUM MECHANICS DO?
Besides nuclear weapons and nuclear power?
Lasers,
computers,
solid state electronics,
medical imaging technology (NMR and MRI),
global positioning systems,
more reliable aircraft and navigation systems,
cell phones,
the internet,
electronic automotive ignition systems ,
LED lighting,
solar energy systems,
bio-medical instrumentation
THE IMPACT
Between 1950 and 2015 the world’s population went from 3 B to 7 B.
Quantum mechanics contributed to this growth through the
effects of the technologies indicated and will through the
developing field of miniaturized and personalized technologies.
It will play a role in leading to more efficient solar energy
systems, higher temperature superconductors, continuing
Moore’s Law and many other things we can’t even imagine just
now.
One area all three critical contributions of Physics can be used is
to find ways to bring clean water and better waste disposal to all
people. Water borne diseases are endemic and easy to
prevent but hard to deal with in all societies.
THE QUANTUM MECHANICS REVOLUTION –
SCORE 3 FOR PHYSICS
There may be more.
ARE WE ALONE ?
Is the earth the only rock in the universe that is aware of the universe?
Whether it is yes or no, the answer to this question is the most awe inspiring
humanity seeks. Hence the Search for Extra-Terrestrial Intelligence or SETI.
Until now SETI has been underfunded and “under-technologied”!
Except for the movie Contact and an occasional Nova
program the public knows little about SETI.
This is about to change. Yuri Milner, a multi billionaire has
donated $100 M to SETI and in 2016 the effort will
expand dramatically.
THE NEW SETI
Quantum mechanics has made possible new technologies that will
allow a dramatic expansion of SETI in 2016 to scan over 100 M star
systems for signals at 10 B radio frequencies.
These are in the Milky Way and outside it.
There will also be optical scanning to look for laser signaling.
The data rate will be 10 Gbytes/sec so many supercomputers
and distributed computers will be used to examine the data for
signals. The Internet is critical.
2016 will be the start of a 10 year effort.
THE TOOLS OF THE NEW SETI
The new SETI will use :
the 100 m Green Banks
Telescope in West Virginia,
the 64 m Parkes Telescope in
New South Wales, Australia,
and
the 2.4 m Optical telescope
at the Lick Observatory near
San Diego, California.
WE HAVE TO GET OUT OF HERE
As you can see if nothing else
happens (in 3 B years the Milky
Way and Andromeda will
collide) the sun will warm up
and boil off of all the earth’s
water in less than 3 B years.
If humanity lasts long enough and is to survive it must
spread out to other planets.
Since we don’t yet know how to exceed c it will involve
multi-generational, one way trips.
PHYSICS, BIOLOGY, CHEMISTRY, ENGINEERING, MATERIALS
SCIENCE AND PSYCHOLOGY ALL WILL HAVE TO HELP
Contribute to longer human lifetimes. Maybe miniaturize humans.
Greatly miniaturized and more efficient propulsion systems.
Reliable quantum computing for data storage and access.
Techniques to make humans and animals more efficient in
use of resources (food and water) and in waste reprocessing.
I doubt that warp drives or worm hole travel will
actually happen but given time and creative minds
something might happen to allow for travel nearer
to c than we can now imagine.
BEFORE GETTING OUT OF HERE
Unlike any other species of any sort except microbes we
have to survive long enough to accumulate the skills and
wills to try to move on.
It will be very expensive and psychologically difficult.
None of us will be here when that time comes, if it ever
does, but in the meanwhile we can contribute to the
knowledge base that might help.
MY CLASS
If you found this sort of stuff interesting and
would like more in depth discussion
please sign up for my special topics class
in the spring of 2016. It is called “The
History of Physics, Cultural Connections
and Other Issues”
Thank you.