Little atom history


From his beautiful Sicilian villa in Agrigente, the Greek Empedocle (around 492-432 BC.) divided matter into four elements, that he also called "roots":

earth air

These elements are walled in by the forces of love and hate.
With absolute love, they form an homogenous unity, whereas hate separates them. While these two continue to enter into conflict, the mixing of elements gives rise to all material things.
This vision of matter in some ways pre-empted our own, with the notion of elements bound by forces of attraction and repulsion.


The word "atom" comes from the greek "a-tomos" and signifies "indivisible". This notion was invented by Leucippe of Milet in 420 before J.C.

His disciple, Democrite of Abdere (around 460-370 BC.), explained that matter was made up of particles in perpetual motion and endowed with ideal qualities:

  • invisible because of their extremely small size
  • indivisible as their name indicates
  • solid (no void inside)
  • eternal because they are perfect
  • surrounded by an empty space (to explain their movement and changes in density)
  • having an infinite number of shapes (to explain the diversity observed in nature)
  • The atom is it Greek in origin?

    It seems that at the same epoque as that of Leucippe, there existed in India a philosophy (system Vaiseshika) which already taught that matter was formed from indestructible atoms: Their assemblies into visible things is degradable and, at the end of a worldly period, the atomic bonds dissolve, then after a period of rest, reunited themselves into a new world...No Greek monopoly on atoms then...

    3.7.2000: Adams James wrote to me:

    It is from a book on the Bhagavad Gita:
       "The phenomenal world or material world is also complete in itself because the twenty-four elements of which this material universe is a temporary manifestation are completely adjusted to produce complete resources which are necessary for the maintenance and subsistence of this universe. There is nothing extraneous, nor is there anything needed. This manifestation has its own time fixed by the energy of the supreme whole, and when its time is complete, these temporary manifestations will be annihilated by the complete arrangement of the complete. There is complete facility for the small complete units, namely the living entities, to realize the complete, and all sorts of incompleteness are experienced due incomplete knowledge of the complete."

       Today, We discovered there are 12 particles and the 12 corresponding antiparticles, from which we get 24 building blocks for all existing matter. 

    Isn't it incredible ?

    The Greek atomist doctrine lay forgotten in the dark throughout the long centuries and left in its place a durable triumph of the theory of four elements of Empédocle.


    Originating in the Middle Ages, alchemy was born from the progress of metallurgy and from the inadequacy of the theory of the 4 elements for representing the diversity of matter.

    The "grand plan" of alchemy was to achieve the transmutation of lowly metals (like copper) into "noble" metals such as gold. Without doubt because the success of such "Grand Works" (transmutation) opened up prospects of wealth and power, the activities of alchemists were surrounded by secrecy and were performed using extremely ancient processes of the esoteric and of the occult.
    The beginnings of alchemy (like those of astrology for that matter) established symbolic links which united the microcosme and macrocosme (the world of planets). For example, the element Lead was associated with the planet Saturn because Saturn appears to us have a "leaded" yellow colour.
    In spite of their esoteric beliefs, alchemists developed the observation, experimentation, measurement and classification of the elements: alchemy is therefore a respectable precursor of chemistry. Anyway, don't forget that Newton was adept at alchemy and that today's physics has turned the old dream of transmutation into reality by transforming certain atoms into other atoms.


    In 1869, the russian chemist Dimitri Mendeleïev constructed a table which classified all of the chemical elements known at that time according to their chemical properties. This table later served to methodically classify all of the atoms, both natural and man made, by their atomic number (that is to say the number of protons that they contain).


    Then in 1897, Thompson discovered the first component part of the atom: the electron, a particle with a negative electric charge.
    In 1904, he proposed an initial model of an atom, since nicknamed "Thompsons pudding".
    He imagined the atom as a sphere full of an electrically positive substance mixed with negative electron "like the raisins in a cake".


    In 1912, Rutherford (New Zealand physicist) discovered the atomic nucleus.
    His new model of the atom showed that its positive electric charge and the majority of its mass were concentrated in an almost point sized nucleus.
    The electron in an atom moves around this nucleus like planets around the Sun, and the attractive electric force (the - charge of the electron attracting the + charge of the nucleus) plays the role which gravity plays for the planets; which is where we get the name "atomic planetary model".
    It is worth noting that in contrast to the atom of the Greeks, Rutherford's is neither indivisible (because it's a composite structure), nor is it solid as it contains mostly empty space: The distance nucleus-electrons is 100,000 times greater than the diameter of the nucleus itself (diameter of the nucleus = 10-15 metres = 1 Fermi).


    Rutherford understood that the nucleus is itself composed of nucleons. These nucleons are of two types:

    The neutron was effectively discovered in 1932 by Chadwick.

    The planetary model of the atom has a serious deficiency. The electrons can emit light under certain conditions (in an electric light bulb for example); in doing so, they lose energy and should therefore get dangerously close to the nucleus right up until they crash into it!
    Such an atom would not therefore be stable.


    In order to take account of atomic stability, in 1913 Niels Bohr created a new model of the atom:
    The orbits of the electrons can't be just anywhere but are "quantified"; only certain particular orbits are permitted for the electron. It's not until one jumps from one orbit to another that it can emit (or absorb) light.



    Bohr's model is the last model obedient to classical physics, that is to say physics which explains movements and phenomena in terms of our human scale. These models of atoms are therefore easy to understand and to represent.
    What an intellectual pleasure (and what laziness!) to represent atoms in the form of little balls turning one around another...
    This model is, moreover, still the one which the general public has in their heads.
    In fact this model is false because at the atomic scale, new laws apply! These laws are part of a strange physics, very far from our current concepts: quantum physics.


    Before continuing our descent towards the constituents of the nucleus and discovering what quantum physics is and its consequence on the representation of the atom, let's just look at what physicists knew about the atom in the 1930s:

    For the lazy and as a world exclusive: the crazyflash, a quick summary of the web page:

    crazyflash: THE PREHISTORIC ATOM
    • The Greeks and the Indians are mediums: together they imagine that matter is made up of little unbreakable balls: the atoms.
    • In the Middle Ages, the 4 elements of father Empedocle come back into service: Alchemists get excited and dream of making gold bars by transmutation.
    • 1897: uncle Thompson (???? qui a une case en moins ???) sees electrons in his cake.
    • 1912: Rutherford (a New Zealander) cuts his teeth on the atomic nucleus: a cluster of protons and neutrons.
    • All that is 'Bohrdélique' (editors note -- french pun on Bohr meaning a shambles in a brothel like way --): electrons must stay on precise trajectories.