Inflation and the CMB   I have just applied a fairly significant edit to a new paragraph added on the CMB and inflation There is indeed an important role for inflation in explaining the exceptional smoothness of the CMB but the previous description had some subtle technical issues Its not actually correct to speak of inflation as expanding faster that light The rate of expansion is not a velocity in the normal sense of the word Even with a conventional linear expansion there are galaxies that are receding faster than the speed of light and which are still visible The distinguishing feature of inflationary expansion is that photons from a galaxy that is receding from an observer faster than the speed of light can never actually overtake the expansion and reach that observer But with other expansion rates photons can actually pass from a galaxy to an observer even when the galaxy is receding faster than the speed of light from that observer  The edit I applied can be reviewed here