This is the most & powerful theory,which help me about nature of universe

                   Theory of relativity

The theory of relativity, or simply relativity in physics, usually encompasses two theories by Albert Einstein: special relativity and general relativity.^[1]
Concepts introduced by the theories of relativity include:

• Measurements of various quantities are relative to the velocities of observers. In particular, space contracts and time dilates.
• Spacetime: space and time should be considered together and in relation to each other.
• Space is a physical entity that can be changed, space is not just nothing, space can affect mass (gravity)^[2]
• The speed of light is nonetheless invariant, the same for all observers.

The term "theory of relativity" was based on the expression "relative theory" (German: Relativtheorie) used in 1906 by Max Planck, who emphasized how the theory uses the principle of relativity. In the discussion section of the same paper, Alfred Bucherer used for the first time the expression "theory of relativity" (German: Relativitätstheorie).
 

Scope:-

The theory of relativity transformed theoretical physics and astronomy during the 20th century. When first published, relativity superseded a 200-year-old theory of mechanics created primarily by Isaac Newton.^[5][6][7]
In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in the nuclear age. With relativity, cosmology and astrophysics predicted extraordinary astronomical phenomena such as neutron stars, black holes and gravitational waves.