A diagram that shows the relationship between the two types of light sources. On the left side of the image, there is a curved line that goes from the top left corner to the bottom right corner. The line is labeled "Conformal Time" and has a green dot in the center. The green dot is the focal point of the diagram. On the right side, there are two circles, one labeled "Past Light-Come" and the other labeled "Last-Scattering Surface". The circles are connected by arrows, indicating the direction of the light source. The arrows are pointing towards the left and right sides of the circle, indicating that the light is passing through the last-scattering surface. There is also a triangle at the bottom of the triangle, which is labeled as "Recombination". This triangle is used to measure the frequency of light emitted by the light sources, as indicated by the green dot. The triangle also has a red arrow pointing to the right, indicating a decrease in the frequency. The diagram also has text that explains that the two light sources are the same size and shape as the last scattering surface.
User viviier uploaded the image
User viviier uploaded the image
