2005- International Year of Physics


...The year 2005 has been declared the International Year of Physics by UN and the International Union of Pure and Applied Physics (IUPAP) with the mission of promoting the interest in this science and at the same time fight against the prejudices towards the scientific labour.
Why in 2005?
Because it is celebrated the 100 years of the birth of Modern Physics, a fact triggered by the 4 works by Albert Einstein, published in the German magazine "Annalen der Physik". These four articles are known as those of the "Annus Mirabilis" (Extraordinary Year). They are summarized below:

i) March 18th 1905: The Photoelectric effect
According to the experts, the four works by einstein in year 1905 deserved the Nobel prize. However, it was the first of those four "An heuristic point of view about the production and transformation of the light" the one who made Einstein receive the Nobel Prize in 1921. Five years before, Max Planck had dared himself to quatize the energy to explain the "Radiation of black body". The same did Einstein to explain the "photoelectric effect" , which consists in the collision between a photom or a "particle of light" and an electron of the surface of a metal (this phenomenom can't be explained in ondulatory terms)
... To the photoelectric effect happens that

Ekmáx = maximun kinetics energy acquired by the electron
hn = energy of the light particle
f = work function of the metal (minimum energy of an electron linked to a metal)

ii)May 11th 1905: The Brownian Movement
Under the title of "About the movement - recquired by the heat molecular kinetics theory - of little particles suspended in a stationary liquid", einstein provided an experimental irrefutable evidence about the existence of the atoms. The Physicist Wilhelm Ostwald (an anti-atomist), was converted to atomist then of knowing the work by Einstein.
... To the Brownian movement, happens that

<r2(t)> = medium quadratic displacement in the instant t
D = coefficient of difusion
t = time

iii) June 30th 1905: Special Relativity
In the third article titled "About electrodynamics of the bodies in movement", Einstein solved the incompatibility between Electromagnetism and Mechanics thanks to the theory of Special Relativity. In this work it was showed that the observers should measure the same speed c = 3*108 m/s to the light (independent of the movement)
... To satisfy the principle of the Special Relativity, the Galileans Transformations should be substituted by the transformations of Lorentz:

iv) September 27th 1905: Equivalence between mass and energy
In the article "Does it depend of innercy the content of energy?", Einstein deduced the existence of a third form af energy (apart of the kinetics and potential clasic). This "condensed" energy corresponds to the mass or "resting energy". In the absence of fields, the total energy of an object of mass m is:

Bruselas, 1927