Tag Info

New answers tagged

2

Basically it means that in the case of OAM=0 the wave fronts make a structure similar to a stack of plates, and in the case of OAM=1 they make a helix-like structure, and 1 refers to the helix multiplicity (for a double helix it would be 2 and so on). One cannot be changed to the other continuously, so this is a topological feature. There are other ...


-1

Mantras like “the Bloch sphere contains all of the observable information about the system” are junk. This implicitly refers to the concept of a (pure) quantum state, and confuses it with an important concept of observable, but quantum states are a tricky stuff and the word “information” may become especially treacherous. Let us start from mathematics. ...


3

I think that "observable universe" is not defined precisely enough to make such statements about it. The spacetime events that we can see are the events on our past light cone. That light cone intersects the last-scattering surface (about 400,000 years after the big bang) in an approximate sphere. By convention the light cone is cut off there (because we ...


0

Richens & Berry [Physica 1D, 495-512 (1981)] give beautiful examples of such systems (with phase-space that is a surface of genus > 1), which they call pseudointegrable; their examples are invariant manifolds of billiards shaped as polygons with rational angles. These systems are interesting because there are two constants of motion, so invariant ...



Top 50 recent answers are included