Question

What is cosmological constant?

Answer 1

As per your grade the concept is a little complex , but still if you could understand the explanation .

Cosmological constant was introduced by Albert Einstein as an addition to his theory of general relativity to "hold back gravity" and achieve a static universe, which was the accepted view at that time. The gravitational effect of matter caused an acceleration in this model which Einstein did not want, since at the time the Universe was not known to be expanding . Thus Einstein introduced a cosmological constant into his equations for General Relativity. This term acts to counteract the gravitational pull of matter, and so it has been described as an anti-gravity effect.