Ciro Santilli @cirosantilli 37

Sets are unordered, but we can use them to create ordered objects, which are of fundamental importance. Notably, they are used in the definition of functions.

Describes perfect lossless waves on the surface of a string, or on a water surface.

Uniqueness: math.stackexchange.com/questions/1113622/uniqueness-of-solutions-to-the-wave-equation

As mentioned at: math.stackexchange.com/questions/579453/real-world-application-of-fourier-series/3729366#3729366 from solving partial differential equations with the Fourier series citing courses.maths.ox.ac.uk/node/view_material/1720, analogously to the heat equation, the wave linear equation can be be solved nicely with separation of variables.

Combination of other sub-Lagrangians for each of the forces, e.g.:

Precursor organization to the Oak Ridge National Laboratory, name that it took in January 1948.

Produced the enriched uranium used for Little Boy, located in the area/predecessor of Oak Ridge National Laboratory.