scale: The relative size of a quantity as compared to some other quantity in a given context. (see above aside and the def of order of magnitude)

scientific notation: A style of expressing numbers in a convenient manner. The number 524 is written as 5.24e2 or 5.24x10² which is 5.24 multiplied by 10 squared: 5.24 x 10 x 10 = 52.4 x 10 = 524. While this may not seem convenient for numbers near one or ten, it is more obviously convenient for numbers like 0.000000524, which is 5.24e-7, or 5.24x10^-7, or 5.24 divided by 10, seven times. (The negative in the exponent means that you should divide instead of multiply.) If this is not clear, and you are interested, feel free to e-mail me.

semi-conductor: A material which has a medium-sized energy gap is a semi-conducting material. A semi-conductor may conduct electricity; while it conducts better than an insulator, it does not conduct as well as a conductor. (See also doping)

solstice: As the orientation of the Earth (relative to the sun) varies through the year, the sun appears to move across the sky a little higher in the sky or a little lower.  During the winter, the sun is lower; in the summer, higher.  During the northern hemisphere summer, the southern hemisphere sees the sun lower in the sky and experiences winter.  During the northern hemisphere winter, the southern hemisphere sees the sun higher in the sky and experiences summer.  The word solstice came to Middle English from the Latin solstitium (via Old French) combining sol- (sun) and -stitium (a stoppage), meaning "the sun stands still."  This is the time of the year when the Sun stops drifting north or south and begins moving in the opposite direction.  The solstice, thus marks the half-way point for the long days of summer and the short days for winter.   The northern hemisphere's summer solstice (when the Earth's north pole is tilted its maximum amount towards the Sun) is the southern hemisphere's winter solstice.  And vica versa (when the south pole is tilted its maximum amount towards the Sun).   (See also equinox)

spacetime:

spacetime, Euclidean: This description of spacetime treats only the geometry of flat surfaces such as a tabletop. The surface of a globe, for example, is not a two-dimensional Euclidean surface; it is a three-dimensional Euclidean surface.

spacetime, non-Euclidean: This description of spacetime treats a more general case than that of Euclidean spacetime. In non-Euclidean geometry, one can treat the surface of a sphere, for example, as a two-dimensional surface.

speed (see also velocity, and vector, scalar, and magnitude)

spin: (see angular momentum)

standard model:

statistical mechanics: (See mechanics, statistical; statistics, Maxwell-Boltzmann; statistics, Fermi-Dirac; statistics, Bose-Einstein; boson; fermion)

statistics, Maxwell-Boltzmann: statistics which describe the motion of particles without accounting for their spin.

statistics, Fermi-Dirac: statistics which describe the motion of particles with half-integral spin. (ie fermions)

statistics, Bose-Einstein: statistics which describe the motion of particles with integral spin. (ie bosons)

strong force: (see force, strong interaction)

symmetry:

system, electrical: A collection of electrical devices connected with electrical circuits to achieve some end. A communication system can contain a microphone (transducer), an oscillator, a modulator, a transmitting antenna, a receiving antenna, a detector, amplifiers, and a speaker (transducer).