| String Theory (Superstring Theory):
A theory which postulates that the fundamental ingredients of the universe are tiny strings of matter (on the tiny scale of thePlanck Length of around 10-35 metres) which vibrate in a space-time of ten dimensions. It is considered one of the most promising of the quantum gravity theories which hope to unite or unify quantum theory and the General Theory of Relativity, and apply to both large-scale structures and structures on the atomic scale.
Superstring theory (short for supersymmetric string theory) is a refinement of the more general theory of strings.
Strong Nuclear Force:
Also known as the strong interaction, this is the powerful but short-range force that holds protons andneutrons together in the nucleus of an atom despite the electromagnetic repulsion of same-chargeparticles, as well as holding together the constituent quarks which comprise neutrons and protons. It is one of the four fundamental forces of physics (along with the gravitational force, the electromagnetic force and weak nuclear force), and the most powerful, being 100 times the strength of theelectromagnetic force, about 1013 times as great as that of the weak force and about 1038 times that of gravity.
The force is mediated by elementary particles called gluons which shuttle back and forth between the particles being operated on and "glue" the particles together. Unlike the other forces, the strength of the strong force between quarks becomes stronger with distance, acting like an unbreakable elastic thread. However, it only operates over a very small distance (less than the size of the nucleus), outside of which it fades away abruptly.
Supernova:
A cataclysmic explosion caused by the collapse of an old massive star which has used up all its fuel. For a short time, such an explosion may outshine an entire galaxy of a hundred billion ordinary stars. It leaves behind a cloud of brightly coloured gas called a nebula, and sometimes a highly compressed neutron star or even a black hole.
Superposition:
The ability in quantum theory of an object, such as an atom or sub-atomic particle, to be in more than one quantum state at the same time. For example, an object could technically be in more than one place simultaneously as a consequence of the wave-like character of microscopic particles.
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