World Year of Physics 2005

Einstein wrote five research papers in 1905, which laid the foundation for Modern Physics. Coinciding with the centenary of Einsteinís ďMiraculous YearĒ, the United Nation has declared 2005 as the International Year of Physics.


Credit: American Institute of Physics

Albert Einstein was awarded the Nobel Prize for Physics in 1921 for "for his services to Theoretical Physics and especially for his discovery of the law of the photoelectric effect". Sir Isaac Newton wrote to his bitter rival, Robert Hooke, "If I have seen farther, it is by standing on the shoulders of giants".This is how breakthroughs in science are achieved, when giants stand on the shoulders of giants! Einstein was extremely smart to realize many important experimental results of his time. In this page we list the great experiments of 19th and 20th centuries that shaped what is known today as Modern Physics. Each listing is linked to a detailed site.

Important Experiments in Physics


Einstein resources


1.      Double-Slit Experiment

2.      Discovery of Helium (1868)

3.      J. J. Thompson Discovery of Electron (1887)

4.      Zeeman Effect (1902)

5.      Magnetic Field of the Sun (1908)

6.      Michelson-Morley Experiment (1887)

7.      Millikanís Oil Drop Experiment (1910)

8.      Raman Effect (1930)

9.      Rutherfordís Alpha Particle Scattering Experiment (1911)

10.  Sir Arthur Eddington Solar Eclipse Experiment (1919)

11.  Discovery of Neutron by James Chadwick (1932)

12.  Discovery of Cosmic Microwave Radiation byArno Penzias and Robert Wilson (1965)

13.  Discovery of Pulsar by A. Hewish Pulsar (1968)

14.  Detection of W and Z particles (1976)

15.  Achieving the Nanokelvin Temperature (1995)


1.      Five papers that shook the world

  1. Einsteinís random walk
  2. 1905: Einsteinís paper revolution
  3. Evicting Einstein
  4. Einsteinís papers
  5. Living Einstein
  6. Einstein Rings
  7. Discovery of the First "Einstein Ring" Gravitational Lens
  8. Visual Distortion Effects in a High Gravity Environment

(Nemiroff, R. J., American Journal of Physics, 61, 619 (1993))

  1. Why did Einstein not receive the Nobel Prize for the Theory of Relativity?
  2. Physics 2005
  3. A book ďThe Illustrated on the Shoulders of Giants: The Great Works of Physics and AstronomyĒ, by: Stephen Hawking


Great spirits have always encountered violent opposition from mediocre minds. - Einstein

Department activities for the International Physics Year

San Fernando Observatory | CSUN | College of Mathematics and Science | Department of Physics and Astronomy

The 1905 Papers


1. "A New Determination of Molecular Dimensions" (Einstein's doctoral dissertation) (30 April 1905)
Buchdruckerei K. J. Wyss,
Bern, 1906, Also: Annalen der Physik, 19 (1906), pp. 289-305.


This is Einstein's doctoral dissertation, submitted to the University of Zurich. Here, he uses available physical data on the diffusion of sugar in solution and the effect of dissolved sugar on the solution's viscosity to determine the size of sugar molecules and Avogadro's number. He gives a measure of the real size of the molecule that makes the kinetic theory of heat more robust. It is his least impressive and most cited work of 1905.


2. "On the motion of small particles suspended in liquids at rest required by the molecular-kinetic theory of heat." (Brownian motion paper) (May 1905; received 11 May 1905), Annalen der Physik, 17(1905), pp. 549-560.


In this paper Einstein relates the random motion small particles suspended in water to Brownian motion and develops the kinetic theory of heat. The prediction is a powerful test of the truth of the kinetic theory of heat. It provides a way to estimate Avogadro's number.


3. "On the electrodynamics of moving bodies" (special relativity) (June 1905; received 30 June 1905)
Annalen der Physik, 17(1905), pp. 891-921.

In this paper, Einstein develops the special theory of relativity. The absence of ether was already demonstrated by the Michelson-Morley Experiment. The result of this experiment was fully exploited in developing the theoretical idea here. Einstein shows that Maxwell-Lorentz electrodynamics has in fact always obeyed a principle of relativity of inertial motion. This is a classic example of how a negative result leads to profound idea.


4. "Does the inertia of a body depend on its energy content?" (E=mc2) (September 1905; received 27 September 1905)

Annalen der Physik, 18(1905), pp. 639-41.


A brief follow-up to the special relativity paper that derives famous relation E = mc2.


5. "On a heuristic viewpoint concerning the production and transformation of light." (light quantum/photoelectric effect paper) (17 March 1905),

Annalen der Physik, 17(1905), pp. 132-148.


In this paper, Einstein gives his famous theory of Photoelectric effect. He looks at the thermodynamic properties of high frequency heat radiation and finds that this radiation behaves just like a collection of many spatially localized "quanta" of energy of magnitude hf, where h is Planck's constant and f is frequency. This was a revolutionary idea leading to his Noble Prize.

Please send your comments to:

Debi Prasad Choudhary

Department of Physics and Astronomy

California State University Northridge

18111 Nordhoff Street, Northridge, CA, 91330-8268