Einstein 1905 and the birth of modern physics

Einstein Year Einstein 1905 w Nature of Light w Atomic Theory w Special Theory of Relativity

Early Years w Born in Ulm (D) 1879 w Primary and secondary school (MUC) w Family move to Milan 1894 w Aarau Gymnasium (SCH) 1895 w ETH (ZUR) 1896

Student Years w Not a model student w Lack of interest w Diploma in maths and physics 1900 w Unable to find University assistantship w Temporary schoolteaching

Bern 1901 - 1905 w Tech expert in Swiss Patent Office (Bern) w Swiss citizenship in 1901 w w Daughter with Mileva Maric in 1902 Adoption Married in 1903 Son in 1904

Bern 1901 -1905 w Engineering problems (day) w Fundamental physics problems (night) w Olympia Academy of Philosophy w Arrival of Micheal Besso w Five scientific papers on thermodynamics

Contemporary Physics w Mechanics w Electromagnetism F = ma Law of Gravity Elec +Mag =EM Light = electromagnetic wave w Radiation Planck’s Law w Radioactivity Energy mystery

Einstein 1905 w The Nature of Light (cornerstone of quantum theory) w Atomic Theory (reality of atoms) w Special Theory of Relativity (physics of relative motion)

I Atomic Theory w Greeks – matter composed of atoms w Dalton – atoms of the chemical elements differ w Avogadro –atoms and molecules w Mendeleev – Periodic Table w Maxwell – Kinetic theory of gases No direct evidence

Einstein and Atomic Theory w Molecular dimensions in liquids w Well received w Statistics of molecular motion in liquids w Fluctuations w Effect on immersed particle - Brownian motion w Mean free path calculation

Einstein and Atomic Theory w 1906 -08 Perrin’s Brownian Motion experiments w 1908 : Confirmation of Einstein predictions Atomic theory = reality w Role of probability and statistics in nature w Einstein established w Nobel Prize for Perrin

II Problems with Light w Radiation studies w Ultraviolet Catastrophe w Planck’s Radiation Law (1900) “Radiation emitted/absorbed in chunks (quanta)” w Mathematical artefact w Applies only to oscillators

Einstein and Light w Einstein : inconsistency in Planck’s Law w Einstein : new statistical approach (1905) “Light itself behaving like particles (quanta)” w Explained Planck’s law, Photoelectric Effect w Conflict with wave theory of light w Rejected for 17 years

III Relativity w Galileo: Principle of Relativity w Laws of mechanics independent of uniform motion w Impossible to detect motion internally w No absolute frame of reference for motion w Newton : absolute space

Relativity and Electromagnetism w Maxwell : electromagnetic theory w Radiation = electromagnetic waves (speed 3 x 108 m/s) light = em wave of speed 3 x 108 m/s w Speed relative to ether ? w Absolute frame of reference for light ? w Experiments

Einstein’s Relativity 1905 w Relativity applies to all laws of physics (includes electromagnetism) w Speed of light = universal constant (general principle) Implication: time and distance not absolute

Implications of Special Relativity w Length of a body w Time interval w Mass of a body

Implications of SR w w Time is relative Time + space = spacetime w Mass is a form of energy E = mc 2

Response to relativity w Controversy (1905 -08) w Kaufmann experiments (1908) w Bucherer experiments (1909) By 1911 Special Relativity accepted

Career Progress w 1905 Ph. D (ETH) w 1908 Privatdozent (Univ Bern) w 1909 Assoc Prof (Univ Zurich) w w 1911 Prof (Univ Prague) 1912 Prof (ETH Zurich) 1914 Prof (Univ Berlin), Director (FW Institute) 1913 Separation

Middle Years (1908 -1916) w Relativity and accelerated bodies (1908 -15) w Principle of Equivalence w General Relativity (1915) “Gravity = curvature of space-time” w Bending of light by gravity w Slowing of time by gravity w Cosmological implications

After the War w 1916 Photoelectric effect w 1919 Evidence for GR 1921 Nobel Prize (Millikan) (Eddington) (Photoelectric effect) w 1923 Compton Effect (light quanta) w 1925 Electron waves (quantum duality)

Between Wars w 1919 w 1920 s w 1930 -33 Remarried Anti-semitism in Germany Einstein’s work attacked Rise of Nazi Party w 1930 -33 Visiting Prof at Caltech (US) w 1933 Hitler assumes power w 1933 Flight to Princeton (US)

Princeton Years (1933 -55) w w Hero’s Welcome American Icon Letter to Roosevelt (1939) Manhattan Project w Regret at Hiroshima (1944) w Nuclear disarmament (1940 s) w Mc. Carthyism (1950 s)

Princeton Years (1933 -55) w Interpretation of quantum theory w Relativity and electromagnetism Unified Field Theory w Evidence for relativity (1950 s) w New York Times Iconic figure

Einstein Today Atomic Theory Reality of atoms Stat. applications Quantum Theory Wave/particle duality Applications Special Relativity Particle physics Nuclear fission and fusion

Einstein Today General Relativity Unified Field Theory Underlies cosmology Evolution of Universe Still not solved Holy grail of physics