Cosmology upsc

How do we know that universe is expanding Upsc?
Edwin Hubble, in 1920, provided evidence that the universe is expanding.
As time passes, galaxies move further and further apart.
Similarly, the distance between the galaxies is also found to be increasing and thereby, the universe is considered to be expanding..
Is cosmology a branch of physics?
Physical cosmology is the branch of physics and astrophysics that deals with the study of the physical origins and evolution of the universe.
It also includes the study of the nature of the universe on a large scale.
In its earliest form, it was what is now known as "celestial mechanics", the study of the heavens..
Cosmology is the scientific study of the large scale properties of the universe as a whole.
It endeavors to use the scientific method to understand the origin, evolution and ultimate fate of the entire Universe.
Information about The Universe covers topics like The Universe, Origin of the universe, Stages in Big Bang Theory, Evidence in support of Big Bang Theory, Stars, Final Stages of a Star̛ s Life, This point will become clearer from the following discussion and The Universe Example, for UPSC 2023 Exam.

How do we know that universe is expanding Upsc?