Author Question: The flatness problem states that a. the density of the Universe is very close to the critical ... (Read 109 times)

SO00 · **on:** Jul 27, 2018

The flatness problem states that

a. the density of the Universe is very close to the critical density.
b. the density of the Universe is much larger than the critical density.
c. the density of the Universe is much less than the critical density.
d. the Universe is two-dimensional.
e. the Universe is one-dimensional.

Question 2

Why can't a massive star generate energy through iron fusion?

What will be an ideal response?

poopface · **Reply #1 on:** Jul 27, 2018

Answer to Question 1

a

Answer to Question 2

Iron is the most tightly bound of all atomic nuclei. Nuclear fusion is able to release energy by combining less tightly bound nuclei into a more tightly bound nucleus, but once the gas in the core of the star has been converted to iron, there are no nuclear reactions that can combine iron nuclei and release energy. The iron core is a dead end in the evolution of a massive star.