It is probable that the radiation now being received as microwave background started when the universe changed "state" from opaque to transparent which may have occurred over years as opposed to seconds much less nanoseconds. The spectrum of this radiation was continuous and as that from the...
There may be a contribution of heat from the Earth's crustal flexing from the variation in the magnitude of the gravitational attraction of the moon and sun and the rotation dynamics of each of the bodies. How about heat generation from the interaction of the Earth's magnetic field and that of...