Universe is the easiest thing to define, yet nobody can fathom.

Universe includes you and all matter, energy, space and even time.

All atoms and molecules consist of about 5%  of the total mass of the universe and 95% has to be made up of something mysterious. At this time those have been named as ‘dark energy’ and ‘dark matter’.

Since the 17th Century, the nature of the Universe as we understand had been changing. In 1686 Sir Isaac Newton presented the 'Law of Universal gravity”. It reveals the fact that matter attracts matter and that gravitational force can act over a very great distance.

He showed that the force of gravity increases  directly with  the masses (directly proportial) while decreases according to the square of the distance (Inversely proportional to square of the distance).

According to this phenomenon all matter, galaxies and space dust must ultimately aggregate into a single enormous mass.

This is not happening.

In 1917 Albert Einstein showed that the universe is static. He introduced a force opposing gravity called a ‘cosmological constant’.

In 1922 Alexandrovich Friedmann (Rus) showed that even according to the Laws of Einstein, Universe could be expanding.

Einstein disagreed with him at first, but later he said, “Introducing a cosmological constant was my biggest mistake”.(Friedman unfortunately died at the age of 37)

Seven years later Edwin Hubble found concrete evidence for the expansion of space.

The rate of expanding helped the astronomers to calculate the size and time of the beginning of the universe. This came to be known as the ‘Big Bang’ theory.

Entire Universe, including time has started 13.8 billion years ago.

By 1998 astronomers discovered that the Universe was not only expanding but the galaxies are accelerating. For this discovery, the Nobel Prize in Physics 2011 was awarded to Saul Perlmutter,  Brian P. Schmidt and Adam G. Riess.

It is obvious that such acceleration could occur only due to a force acting against gravity.

Although this has not been properly understood it is named as ‘Dark energy’or (Vacuum energy). Estimates show that this can account for 68% of the mass of Universe. The estimates also show that this is equivalent to Einstein’s cosmological constant.

After all Einstein may not have made a blunder.

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