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C O U R S E 
Understanding Einstein: The Special Theory of Relativity
Larry Lagerstrom, Stanford University
C O U R S E   L E C T U R E 
Pre-Einstein Physics up to 1905
Notes taken on March 24, 2015 by Edward Tanguay
1800 is good place to start talking about physics
but the term "physicist" was not coined until about 1840
before that people who worked in physics might be called natural philosophers
1800 there was a split based on what "natural philosophers" worked on
organic matter
inorganic matter
the branch that became physics focused on inorganic matter
1800: battery
came out of experiments done on animal electricity
e.g. how we can stimulate nerves in frog legs
Alessandro Volta made an inorganic version of this
significance was that you could get a sustained electric current
before that you could get sporadic electric shocks
you could store limited amounts of electrical current but no sustained electrical current
this opened up many kinds of new inventions over the next 100 years
1800: wave theory of light
before this, Isaac Newton had the theory of gravity
became the greatest mind of the time
so scientist followed his lead on his concept of light as well, light being particles, or straight rays
around 1800, Thomas Young revived the theory of light as waves
1820s: electromagnetism
shown that if you have a sustained current through a wire and you brought a compass needle next to it, it would change directions
clearly a connection between electricity and magnetism
railroads because to carry passengers, connecting cities
electromagnetic induction
mentioned on the first page of Einstein's paper on the special theory of relativity
loop of wire, bar magnet closer to loop, you generate an electric current, as you move the bar magnet back and forth
if you have a wire and can send current down it, then you can make a communication device
Maxwell's equations
synthesized and explained the work that people had been doing with electricity in the past half century
allowed the prediction of electromagnetic waves traveling through space
the classical theory of electromagnetic radiation
traveled at a speed close to the known speed of light
the natural conclusion was that light was an electromagnetic wave
telegraph still expanding
under Atlantic Ocean
expansion of the railroads
in U.S., transcontinental railroad
telegraph and railroad went together
because you need a good signalling system for the trains
synchronizing of clocks
cities before that often had different times
mechanical models
water waves travel through something, disturbances through water
this analogy applied to light assumes that there must be some median that light waves travel through, referred to as "ether"
the French thought the British were going off in the wrong direction
derided their mechanical models, reminded them of the factory system
the French physicists prided themselves on clarity and rationality of thought
interesting to reading obituaries of these scientists
British: creativity
French: rationality and clarity of thought
physics division of labor
theoretical physicist
experimental physicist
Masters Degree in Engineering from MIT
19th century
experimental physicists were at the top
theoretical physicists really didn't exist
German universities you typically only had one physics professor
they were typically experimental physicist who ran the show
perhaps an assistant
this was the type of world Einstein was born into
by the time he was a physicist things started to change
1879: Einstein born
Incandescent lighting
Edison's great innovation was the whole system of electric lighting
the wires
the switches
the power
Einstein's father and uncle were entrepreneurs in Munich
specialized in incandescent lighting
won contract to supply lighting for Oktoberfest
discovery of electromagnetic waver
Heinrich Hertz
conclusively proved the existence of electromagnetic waves theorized by James Clerk Maxwell's electromagnetic theory of light
Hertz, became a term for units of cycles per second
died in his mid-30s
radio started almost immediately after this
Michelson-Morley experiment
if light waves are going to be traveling through the ether
as the Earth moves around the Sun
at the surface of the Earth, we should have an "ether breeze" in our face
therefore if you shine a light in that direction and in the opposite direct
they found nothing
there was not "ether breeze" effect
made people rethink their theories
the electromagnetic worldview
attempt to "get to the really real" and explain almost everything in terms of electromagnetism
looking at electromagnetism as the basis of physical reality
the electron was discovered in the 1890s
Einstein in college
nature of light
time and space
came at this from a different direction
career up to delivery of his most influential papers