Question

Why is a pinhead sometimes used as an analogy for the early universe?
a) Matter was destroyed during the big bang.
b) At time zero all matter was metallic.
c) At time zero all matter was contained in a very small volume.
d) Matter was rapidly dispersed by the big bang.

Answer 1

The answer is (C), The singularity that was the source of the big bang was really small. That is why it is refereed to as a "pinhead".  

Answer 2

Answer is c). At time zero all matter was contained in a very small volume.

All of the matter and energy in the universe was in a region smaller than the head of a pin and all of the energy and matter in the universe suddenly exploded out of a point smaller than the head of a pin.