supergravity
Class of models that generalize Einstein's general theory of relativity in a way that it satisfies the requirements of supersymmetry. Today, supergravity is of interest in the context of string theory: In the limiting case of low energies (where low ...
sun
The central (and most massive) body of our solar system; the star closest to us; a ball of gas with a radius of ca. 700000 km (for comparison the radius of the earth: 12756 km) and a mass of 1.989·1030 kilograms [see exponential notation]. In the interior ...
strong force
One of the four fundamental forces in our universe (the others are electromagnetism, weak nuclear force and gravity). The strong force binds the quarks to form compound particles such as protons and neutrons. Indirectly, it is also responsible for holding ...
string theory
Candidate for a theory of quantum gravity; a quantum theory, where the fundamental building blocks are tiny, one-dimensional, oscillating entities, called strings. A brief description can be found on the page String theory in the chapter Relativity and ...
straight line
In the plane, in three-dimensional everyday space or in more general flat spaces: Any line that forms the shortest connection between two given points. In the spacetime of special relativity: The world-line of an object moving with constant speed on a path ...
stellar black holes
Stellar black holes are black holes with between a few and a dozen solar masses that are formed when the core of a massive star collapses. Basic information about black holes can be found in the chapter Black holes & Co. of Elementary ...
Stefan-Boltzmann law
One of the laws governing the properties of the simplest form of thermal radiation - that emitted by a blackbody: The total energy emitted by such a body is proportional to the fourth power of its temperature (measured in Kelvin). ...
stationary
Roughly speaking, in relativity, a situation or a spacetime is stationary if there is no change over time. To be more precise, one has to take into account that, in general relativity, time can be defined in many different ways, all of them equally valid ...
