Einstein
“the essence of his science lay in his artistry –his phenomenal sense of beauty”
Banesh Hoffman, 1975
Ulm, Germany
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Ulm
Ulm
Germany
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“you will never amount to anything”
In 1880, the Einsteins moved to Munich
Albert developed an intense dislike of school and dropped out at age 15
Albert & Maja, 1893
“I believe in Spinoza’s God who revealshimself in the orderly harmony of whatexists, not in a God who concerns himselfwith the fates and actions of human beings”
Albert Einstein, 1929
Surfing a beam of light
At age 16, Einstein asked himself: what would a light wave look like if one could keep abreast of it ?
He would provide ananswer ten years later……but first he wentto college in Aarau, then Zurich
Aarau class of ‘96MarcelGrossman
Later that year, Einstein entered the EidgenössischeTechnische Hochschule, Zurich. Graduated in 1900.
Technical Expert, Third Class
Einstein got a job at the Swiss Patent Office in Bern, on the 23 June 1902
Six months later, he married his Serbian girlfriend, Mileva
A gathering stormLorentz (1853-1928)Maxwell (1831-1879)
FitzGerald (1851-1901) Max Planck (1858–1947)
1905 – Annus Mirabilis
• 17 March– A new theory of light
• 30 April– A new method to infer size of molecules
• 11 May– A new theory of Brownian motion
• 30 June– A new theory of space and time
• 27 September – m = E / c2
The Photoelectric Effect
No current flows however intense the light
A current flows only if each lightquantum is sufficiently energeticto knock an electron from the metal.
E = h n - W
-
Special Relativity
Principles– The laws of physics are the same in all
inertial frames the principle of relativity
– The velocity of light is independent of the motion of its source or of the observer
Newton’s 5th Deduction
“The motion of bodies in a given vehicle are the same among themselves whether that vehicle is a rest or in uniform motion”
Sir Isaac Newton (1642 – 1727)
Time
d = c t
d = distance between A and Bt = time to go from A to Bc = speed of light in vacuum
The speed of light in vacuum isalways the same
A
B
Time
(c T)2 = (v T)2 + d2
c T
v T
d
T = time to go from A to B
But d ≠ c T
2
cv1 ÷øö
çèæ-=Tt
A B
It isd = c t !!!
Moving clocks run more slowly!
But, what Einstein recognized is that this effect must, by the principleof relativity, be perfectly symmetricalbetween different frames of reference.
Cosmic Ray Muons
Time to the ground 20km / 300,000 km/s ~ 7070 microsecond
For every 35microseconds ofour clock, themuon’s “clock” advancesonly 1 microsecond!
~ 20 km
Muon lifetime ~ 22 microsecond
“The happiest thought of my life”In 1907, it suddenly dawned on Einstein that a person falling off a building would be weightless!
http://nssdc.gsfc.nasa.gov
Herr Professor Dr. Einstein
News of Einstein’s radical ideas spread quickly among the leading physicists
This led to many offers of professorships from across the world
In 1914, he became a full professor at the University of Berlin, just at the outbreak of the “War To End All Wars”
Arrows of hate
1920: At the instigation of the Nazi Party, a group of German philosophers was convened to discredit Einstein’s theories.
January 1933: The Nazis come to power in Germany. The Einsteins leave for the USA, never to set foot in Germany again.
Descent into darkness
Einstein, pacifist though he was, concluded that the Nazis were an evil that could be vanquished only by force
2 August, 1939, a month before the start of World War II, he wrote to Roosevelt warning of the grave danger to the world should the Nazis acquire atomic weapons.
we should take care not to make the intellectour God….It cannot lead, it can only serve; andit is not fastidious in its choice of leader
The Global Positioning System
• What is it ?– A system of 24 satellites in orbit about
Earth that provides accurate world-wide navigation
– Each satellite contains an atomic clock, accurate to ~ 1 nanosecond
– Each satellite emits a unique signal giving its position
GPS – ClocksvSatellite
vEarth rSatellite
rEarth
T = time far awayt = time at radius rrS = Schwarzschild
radius
rrTt S−−=
2
cv1
Without correction,the satellite clockswould run fast by 39 microseconds/day39 microseconds/day