Question

Positrons:

1. are a form of anti-matter
2. are destroyed by collisions with protons
3. have masses the same as electrons
4. A, B and C
5. A and C

[19] Which of the following is likely to be true if inflation did NOT happen in the very early universe?

1. The universe would not be expanding today
2. There would be no helium in the universe
3. The universe would be governed by a Theory of Everything Superforce
4. The CMB would vary significantly in its temperature from one side of the sky to the other E) The universe would have re-collapsed in less than 1 second

[20] If neutrons decayed into protons a bit more slowly than their 10 minute lifetime, so that the ratio of neutrons to protons tens of minutes after the Big Bang was larger:

1. We would see less helium in the universe than we see today
2. We would see more helium in the universe than we see today
3. Atoms would not be able to form in the current universe
4. Neutrons would have to be less massive than protons

Answer 1

E. A and C

Positrons are a form of anti-matter. They are the antimatter of the electrons.

They has the same mass as electrons. They are not destroyed by collisions with protons, they bounce off.

D.) The CMB would vary significantly in its temperature from one side of the sky to the other

If cosmological inflation had never happened, and radiation domination continued back until a gravitational singularity, then the mode would never have been inside the horizon in the very early universe.

C.) Atoms would not be able to form in the current universe