Ascientist who studies the structure of the earth

Ascientist is explaining how background cosmic radiation gives evidence of the big bang theory. she says that radiation has been detected everywhere equally as heat in the universe and is increasing. this has been shown to be residual radiation from the big bang. what error did the scientist make?

The desert expands by hundreds of square miles each year.

What man-made lake was created by the building of the hoover dam?