Some people wish that we lived in a recollapsing universe that would eventually stop expanding and start contracting. For this t
o be the case, which of the following would have to be true (based on current understanding)?)? (A) Dark energy is the dominant form of energy in the cosmos. (B) Dark energy does not exist and there is much more dark matter than we are aware of to date. (C) Neither dark energy nor dark matter really exist. (D) Dark energy exists but dark matter does not.
(B) Dark energy does not exist and there is much more matter than current evidence suggests.
Explanation:
The repulsive force which is accelerating expansion of the universe is called as dark energy. Most of matter present in the universe is the dark matter of about eighty five percent.
So, a collapsing universe would not have the dark energy and there is more matter which is not the dark matter. This theory is rejected because expansion of the universe is observable.
Gamma Radiation (γ): Also called gamma rays. Gamma radiation is made of electromagnetic waves, has zero charge and mass, continuously emits heat and has the ability to ionize air and make it conductive of electric current.
Beta radiation (β): Beta rays or beta particles, are electrons, negative particles with charge - 1 and mass number 0.
Alpha radiation (α): Also called alpha particles or alpha rays, are particles charged by two protons and two neutrons. They have positive charge +2 and mass number 4.
