The atomic age history had begun, of course, before August, 1945 when the message about Hiroshima tragedy shocked the world.  Such scientists as Albert Einstein, Niels Bohr, Max Planck, Ernest Rutherford and others  had laid  a strong foundation of Science of Atoms made contribution in development of Nuclear Physics and mastering the secrets of nuclear energy. A pleiad of eminent scientists  from multiple world countries created harmonous Theory of Atoms.  The history of mastering the nuclear energy will look as follows when we chronologically  arrange major tractates and discoveries of great worth resulted in nuclear fission.

Paper of Wilhelm C. Roentgen on "New kind if rays"  had published  in Dec , 1895  laid a foundation of Nuclear Physics.  He called them as Х - rays later re-called as Roentgen rays.

In 1896 Antoine H. Becquerel discovered uranium ore lets out the invisible beams possessing the big getting ability. Later this phenomenon was called as Radioactivity.

In 1898 P. Curie and M. Sklodowska  separated few hundredths of a gram of new substance — an element radiated particles. They called it as Polonium.  In December the same year they discovered a new element - Radium.

In 1911 E. Rutherford  suggested a planetary model of atom. He proved  almost the whole atomic mass is located in its kernel.

In 1913  N. Bohr created model of Hydrogen atom and the Atomic Structure Theory. At that days  Quantum Theory began to grow rapidly so-called actual birth of Nuclear Physics.

In 1932 J. Chadwick  found out a neutral nuclear particle without electric charge - neutron later played  a role of  key to Big nuclear power.

In 1932 D.D.Ivanenko offered a hypothesis of a structure of an atomic nucleus from protons and neutrons.

In 1933 I. and F. Joliot - Curie  discovered an  Induced Radioactivity, a new kind of Radioactivity. It  was of great important in  creation of new radioactive elements.

In 1934 E.Fermi found out that  radioactive elements are formed when neutrons attack uranium . Italian researchers accepted them for heavier elements  than uranium and called as transuranium ones.

In 1934 S.I.Vavilov and P.A.Cherenkov opened one of the fundamental physical phenomena — a liquid luminescence during moving electrons inside  at a speed exceeding phase one.

In 1935 I. V.Kurchatov and all. opened the phenomenon of a nuclear isomerism of artificial radioactive nuclear kernels and developed Theory of this phenomenon.

In 1936 Ya.I.Frenkel offered drop model of a kernel and entered thermodynamic concepts into the nuclear physics; put forward the first theory of nuclear division.

In 1938 O. Hahn and F. Strassmann repeating Fermi's experiences found out that in the uranium irradiated with neutrons there are the elements standing in the middle of periodic system of elements of Mendeleyev and that at neutron hit in a kernel of uranium the kernel collapses — shares a pas two smaller kernels.

In 1939 Ju. B.Hariton and Ya. B.Zeldovich have theoretically shown possibility of realization of chain reaction of division of kernels of uranium-235. It has appeared that the energy allocated at splitting 1 kg of uranium, is equal to that which turns out at burning of the best coal of 2 500 000 kg.

In 1940 G.N.Flerov and K.A.Petrzhak opened spontaneous division of kernels of uranium, i.e. have proved that uranium kernels can spontaneously break up.

In 1940 Yu. B.Hariton and Ya. B.Zeldovich offered calculation of chain reaction of division of kernels of uranium, having established, thus, basic possibility of its realization. In article «Kinetika of chain disintegration of uranium» (the Experimental and theoretical physics, 1940, t. 10) they wrote: «... Mixing uranium with the substances possessing small section of capture (for example with heavy water), or enriching uranium with isotope U to which disintegration under the influence of slow neutrons is attributed, there will be possible a creation of conditions of chain disintegration of uranium by means of branching chains at which as much as weak irradiation neutrons will lead to powerful development of nuclear reaction...». And further «... molar warmth of nuclear reaction of division of uranium in 5-7 time exceeds heat-removing ability of coal...» . Problems of nuclear physics occupied for a long time minds of the Soviet scientists. In 1920 in the country the so-called Nuclear commission has been created. In 1932 at the Leningrad physicotechnical institute the special group on a kernel has been formed. A.F.Ioffe, its assistant — I. V.Kurchatov became the head of group.

In September, 1937 in Moscow the Second all-Union conference on an atomic nucleus has taken place, then meetings in 1938 have followed, 1939 and in 1940 the Indispensable organizer and the participant of these meetings was I. V.Kurchatov. At meeting on an atomic nucleus in November, 1940 Kurchatov discussed concrete ways of realization of chain nuclear reaction, leaning, in particular, against Ju. B.Haritona and Ja. B.Zeldovich's theoretical calculations. It was a question of creation of an uranium copper.