Law of conservation of energy

In classical mechanics space and time were considered independent of each other while according to the theory of relativity given by Einstein, space and time are interrelated.

Space is homogeneous and isotropic and hence we have the laws of conservation of linear momentum and angular momentum. Similarly, time is also homogeneous and isotropic. Due to homogeneity of time we have the law of conservation of energy. According to P.A.M. Dirac, one of the great theoretical physicists of 20th century, the law of conservation of charge may be due to the isotropy of time.

This laws are as under:

⇒ Law of conservation of energy:

The amount of total energy in the universe remains constant. The energy can neither be created nor be destroyed; it can just be converted from one form to the another.

⇒ Law of conservation of charge:

During any process taking place in an electrically isolated system, the algebraic sum of the charges always remains constant.

⇒ Law of conservation of linear momentum:

If the resultant external force on a system is zero, the total linear momentum of the system remains constant.

⇒ Law of conservation of angular momentum:

If the resultant external torque acting on a system is zero, the total angular momentum of the system remains constant.