As stated in the video, the universe was dense and hot after the Big Bang. It eventually
cooled and expanded enough that it became transparent (like we see today). If we look
far enough away (which is also looking back in time, see “lookback” time) we can see the
edge of that hot dense time of the universe. If we had been there during that time, we
would have been able to see it gave off light with our eyes! The wavelength emitted was
in the visible part of the spectrum. It is now billions of years in the future and that light
has been redshifted to the point that we can no longer see that light with our eyes.
- The light has been redshifted so much that the two astronomers in 1965 that found
the signal of this “cosmic microwave background” had to use what kind of telescope to
detect it?
Sample Solution
