Einstein 1905

and the birth of modern physics

Einstein Year

Einstein 1905

Nature of Light Atomic Theory

Special Theory of Relativity

Early Years

Born in Ulm (D) 1879 Primary and secondary school (MUC) Family move to Milan 1894

Aarau Gymnasium (SCH) 1895 ETH (ZUR) 1896

Student Years

Not a model student Lack of interest Diploma in maths and physics 1900

Unable to find University assistantship Temporary schoolteaching

Bern 1901- 1905

Tech expert in Swiss Patent Office (Bern) Swiss citizenship in 1901

Daughter with Mileva Maric in 1902 Adoption Married in 1903 Son in 1904

Bern 1901-1905

Engineering problems (day) Fundamental physics problems (night) Olympia Academy of Philosophy

Arrival of Micheal Besso Five scientific papers on thermodynamics

Contemporary Physics

Mechanics F = maLaw of Gravity

Electromagnetism Elec +Mag =EM Light = electromagnetic wave

Radiation Planck’s Law

Radioactivity Energy mystery

Einstein 1905

The Nature of Light(cornerstone of quantum theory)

Atomic Theory(reality of atoms)

Special Theory of Relativity(physics of relative motion)

I Atomic Theory

Greeks – matter composed of atoms Dalton – atoms of the chemical elements differ Avogadro –atoms and molecules

Mendeleev – Periodic Table Maxwell – Kinetic theory of gases

No direct evidence

Einstein and Atomic Theory

Molecular dimensions in liquids Well received

Statistics of molecular motion in liquids Fluctuations

Effect on immersed particle - Brownian motion Mean free path calculation

Einstein and Atomic Theory

1906-08 Perrin’s Brownian Motion experiments 1908 : Confirmation of Einstein predictions

Atomic theory = reality

Role of probability and statistics in nature Einstein established Nobel Prize for Perrin

II Problems with Light

Radiation studies Ultraviolet Catastrophe Planck’s Radiation Law (1900)

“Radiation emitted/absorbed in chunks (quanta)”

Mathematical artefact Applies only to oscillators

Einstein and Light

Einstein : inconsistency in Planck’s Law Einstein : new statistical approach (1905)

“Light itself behaving like particles (quanta)”

Explained Planck’s law, Photoelectric Effect

Conflict with wave theory of light Rejected for 17 years

III Relativity

Galileo: Principle of Relativity Laws of mechanics independent of uniform motion

Impossible to detect motion internally No absolute frame of reference for motion

Newton : absolute space

Relativity and Electromagnetism

Maxwell : electromagnetic theory Radiation = electromagnetic waves (speed 3x108 m/s)

light = em wave of speed 3x108 m/s

Speed relative to ether ? Absolute frame of reference for light ? Experiments

Einstein’s Relativity 1905

Relativity applies to all laws of physics

(includes electromagnetism)

Speed of light = universal constant

(general principle)

Implication: time and distance not absolute

Implications of Special Relativity

Length of a body

Time interval

Mass of a body

220 /1)( cvLvL

220 /1/)( cvtvt

220 /1/)( cvmvm

Implications of SR

Time is relative Time + space = spacetime

Mass is a form of energy

E = mc2

Response to relativity

Controversy (1905-08) Kaufmann experiments (1908) Bucherer experiments (1909)

By 1911 Special Relativity accepted

Career Progress

1905 PhD (ETH) 1908 Privatdozent (Univ Bern) 1909 Assoc Prof (Univ Zurich)

1911 Prof (Univ Prague) 1912 Prof (ETH Zurich) 1914 Prof (Univ Berlin), Director (FW Institute) 1913 Separation

Middle Years (1908-1916)

Relativity and accelerated bodies (1908-15) Principle of Equivalence General Relativity (1915)

“Gravity = curvature of space-time”

Bending of light by gravity Slowing of time by gravity Cosmological implications

After the War

1916 Photoelectric effect (Millikan)

1919 Evidence for GR (Eddington)

1921 Nobel Prize (Photoelectric effect)

1923 Compton Effect (light quanta)

1925 Electron waves (quantum duality)

Between Wars

1919 Remarried 1920s Anti-semitism in Germany

Einstein’s work attacked 1930-33 Rise of Nazi Party

1930-33 Visiting Prof at Caltech (US) 1933 Hitler assumes power 1933 Flight to Princeton (US)

Princeton Years (1933-55)

Hero’s Welcome American Icon Letter to Roosevelt (1939) Manhattan Project

Regret at Hiroshima (1944) Nuclear disarmament (1940s) McCarthyism (1950s)

Princeton Years (1933-55)

Interpretation of quantum theory Relativity and electromagnetism

Unified Field Theory

Evidence for relativity (1950s) 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 Underlies cosmology

Evolution of Universe

Unified Field Theory Still not solved

Holy grail of physics