Select all hypotheses that can explain the accelerated expan

Select all hypotheses that can explain the accelerated expansion of the universe. 1)The cosmological constant is proportional to the difference of dark energy and the energy of gravitational effects 2)The cosmological constant is a form of dark matter that would create a positive pressure, thereby leading to a constant-rate expansion of the universe. 3) The cosmological constant is a form of dark energy that would be inherent in space itself and would create a negative pressure, or a repulsive gravitational effect, thereby leading to an accelerated expansion of the universe. 4)The cosmological constant used by Einstein in his general theory of relativity may be adjusted to give a universe that expands at an accelerating rate.

Solution

(3) is correct.

A positive vacuum energy density resulting from a cosmological constant implies a negative pressure, and vice versa. If the energy density is positive, the associated negative pressure will drive an accelerated expansion of the universe, as observed.

(2) is wrong since (3) is correct.

(4) is correct.