Radioactive_(of such metals as radium or uranium) having atoms that break up, and in so doing, send out rays in the form of electrically charged particles capable of penetrating (going deep into) opaque (not allowing light to pass through) bodies and of producing electrical effects.
Radioactive dust (e.g. as carried by winds) from explosion of nuclear bombs etc.
Fission splitting or division (e.g. of one cell into new cells, of the nucleus or central parts of certain atoms, e.g. uranium when an atom bomb is exploded.)
The twentieth century has witnessed the development and use of atomic or nuclear energy for destructive and peaceful purposes on a vast scale. Now, when we are afraid of atomic wars which can cause unthinkable destruction, we feel the satisfaction of enjoying comforts given by cheap electricity by nuclear reactors and ships run on atomic energy, and many more besides. It is surely the destructive use of atomic energy in the production of weapons of mass destruction like the atomic and hydrogen bombs that dominates the world scene today.
Atomic Energy in 21st Century
When the nucleus (central part) of the atom is broken up, tremendous energy is produced. Radioactive elements like uranium have a large number of protons, and they give out radiations (energy in rays, energy or heat waves). These elements are used for producing nuclear energy. The nuclei of these elements are bombarded with high-speed particles, and this result in nuclear fission (splitting or division). This conversion of a small amount of radioactive substance into a very great amount of nuclear energy is the basis of the explosion of an atomic bomb. This explosion produces intense shock waves and radiations highly damaging to living beings The surrounding areas to long distances become contaminated (poisoned) with radio-active fission products.
Atomic Attack on Hiroshima
So, when the first atom bomb was dropped by the USA on Hiroshima in Japan in 1945, 3 square miles of the city were destroyed and 160 thousand people were killed. The second atom bomb dropped by America on Nagasaki in Japan caused even greater destruction. The sky changed from blue to black and black rain began to fall. The walls of the buildings turned into rubble (broken stone and bricks) to miles around the point of explosion. The air was full of radiations.
Now, besides the modem aircraft, short and long-range missiles are in possession of nuclear states. Missiles can -easily be equipped with atomic warheads. The missiles are thrown on enemy territory with their payloads (warheads of missiles). It is not possible to build complete defenses against nuclear explosions except to have anti-missile and anti-aircraft systems to stop the arrival of nuclear warheads.. Unluckily, so many nuclear weapons are available with the nuclear powers that their use can destroy our world several times over. The most painful aspect (facet) of a nuclear war is that its destruction does not remain confined (restricted) to the time during which it continues. After the nuclear explosions the particles radio-active substances in the air go on emitting (giving out) radiations for weeks together. When these particles are carried far by blowing winds, the radiations spread to areas which are not even engaged in war.No country can win a large-scale nuclear war with another nuclear power as both will get destroyed in the process. Besides, the countries affected by the radioactive fallout, even when not participating (taking part) in the war, will suffer unnecessary destruction. A nuclear war, in effect (as a result), will take away human, animal and food resources from the people of the world in large areas and for a very long time. It will bring untold (immeasurable) suffering, uncontrollable disease, unbearable hunger and an unbelievable number of deaths.
Surely, it is in the interest of all humanity to bring all nuclear preparations to an end and to destroy the stockpiles of nuclear weapons everywhere through mutual agreement (consent). The tremendous efforts and huge amounts of money now being spent on nuclear war preparations can well be used for peaceful uses of nuclear energy. The need to have a world-wide agreement on banning the preparation and use of nuclear weapons is the need of the hour. Perhaps much more than a mere (only) signing of the CTBT (Comprehensive Test Ban Treaty) by all countries is