The atomic bomb is the most powerful weapon in the world. It triggers a nuclear chain reaction, which can unleash the energy equivalent of a million, or even a billion, TNT.
The atomic bomb was developed in the Manhattan Project, under the leadership of General Leslie Groves. The first “test” explosion (called “Trinity”) happened on 16 July 1945 at New Mexico’s Alamogordo Test Range.
The atomic bomb is based on the concept that when neutrons are fired at atoms that have very heavy nuclei (like uranium or plutonium) the nuclei break down into lighter nuclei, which in term hit other nuclei. This leads to a “domino effect” and can generate an astounding 80 terajoules of energy per kilogram (TJ/kg). This process is called “fission” and means energy generated from breaking down a nuclei, vs. “fusion” which means energy generated from combining them.
The atomic bomb is powerful that a single blast can wipe out a city, as it did in the Second World War when two were detonated in Japan. While the bombs ended the war—Japan surrendered to the United States—many people fear that they could start another one, and obliterate the human race in the process. Today, seven countries have admitted to owning nuclear weapons: the United States, Russia, the United Kingdom, France, the People's Republic of China, India and Pakistan. It is feared that other countries may have undeclared nuclear weapons. In fact, the United States justified the invasion of Iraq by saying there was “reliable evidence” that the country had nuclear capabilities. (Incidentally, no weapons were found.)