Back in time to the Big Bang (cont.)

Ellen A satellite named COBE (COsmic Background Explorer) has taken a picture of the cosmic background radiation. Imagine: this picture shows the whole Universe! It is one of the great successes of the Big Bang model that it actually can explain the existence of this radiation. It comes from all directions, with very similar intensity.
Tim Isn't that radiation dangerous? It must be very energetic!
Ellen Only at the beginning. But now, the Universe has become more than a thousand times bigger since the time when this radiation was emitted. The waves have been 'stretched', and the energy of the light is now 1000 times less than before.
Tim I see. The cosmic background radiation is the leftover from the matter-antimatter annihilations. And we're all made from the leftover matter.