1. Why is the surface of a white dwarf so much hotter than the surface of a main sequence star with the same mass? If it is so hot, why is it so dim?

2. Do nearby white dwarfs come from stars which were larger or smaller than the Sun? Why do you think so?

Extra Credit

Human life on the earth can only be a few thousand years old, as evidenced
by the present population.  Right now, the population of the earth is
almost 6 billion, and it is growing by about 2 per cent annually.  Even if
you assume that the rate of growth of the population in the past was much
smaller, say only 0.1 per cent, then starting with 2 people 50,000 years
ago, we would have reached a present-day population of 2x(1.001)^50,000,
or about 10^22 (ten thousand billion billon).  This means that the surface
of the earth would be completely covered with people about two million
deep, and the total mass of human beings would be about a tenth the mass
of the earth.  Since this is obviously not the way things are, it is
impossible for humanity to have existed on the earth for anywhere near as
long as 50,000 years.  In fact a growth rate of 0.5 per cent since the
Flood (ca. 2300 B.C.) gives a present population of about 4 billion.