ay45c3-page2 - each point that matters, but also the...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: each point that matters, but also the distribution of which way they are going, and of what energies they have. Since the momentum vector p encapsulates both the latter concepts (direction and energy) it is useful to think, at some instant in time, of each photon being at a point in a 6-dimensional space of position and momentum: (x; y; z; px; py ; pz ) : (I can only draw 2 of the dimensions:) dx dpx p x x The phase space density N is the number of photons dN per 6-dimensional unit phase space: dN = N dx dy dz dpx dpy dpz  N d3x d3p : Things get more interesting if we decide to keep track of the momentum part of phase space in spherical, not Cartesian coordinates. p z d3p = p 2dpd Ω py dΩ is a solid angle px 26 ...
View Full Document

Ask a homework question - tutors are online