Notes on Relativity and Cosmology - Physics Department, UCSB

4.4. 2+1 DIMENSIONS: ABERRATION 113
There is one light ray traveling outward in each direction, and of course the
set of all directions (in two space dimensions) forms a circle. Thus, we may
talk about the circle of light rays. It us convenient to dispense with all of the
other parts of the diagram and just draw this circle of light rays. The picture
below depicts the circle of light rays in the same reference frame used to draw
the above diagram and uses the corresponding colored dots to depict the front,
back, left, and right light rays. I have also added a few more light rays for future
use and I have numbered the light rays to help keep track of them in the black
and white version.
Back
4
6
5
Left
3
7
Right
2
8
1
Front
Light Circle in the Original Frame
Now let’s draw the corresponding circle of light rays from the moving observer’s