"THE MOST INCOMPREHENSIBLE OF THE UNIVERSE IS THAT WE CAN COMPREHEND IT..."
...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
Where:
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
Where:
<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