Currently the most accepted theory that explains how ALMOST the entire universe works is ‘the standard model’. It answers the fundamental question — What is everything made of (particles), and how does it hold together (forces). It is a simple and comprehensive theory that explains all the hundreds of particles and complex interactions. It describes three of the four known fundamental forces (the electromagnetic, weak, and strong interactions) in the universe, as well as classifying all known elementary particles.
It is one of the greatest achievements by mankind by some of the most brilliant minds of the twentieth century. More than a quarter of the Nobel Prizes in physics of the last century are direct inputs to or direct results of the Standard Model.
Notice how I saw almost. This is because the standard model does not incorporate the fourth fundamental force — gravity. And the best theory to describe everything related to gravity is Einstein’s General Theory of Relativity. Combined, these two theories explain the entire universe. However, the standard model used to describe the micro world, and the general theory of relativity used to describe the macro world, are difficult to fit into a single framework (because of the difference in sizes).
Theory of Everything = General Theory of Relativity + The Standard Model
This hypothetical single, all-encompassing theory is called the theory of everything. Stephen Hawking was obsessed with the theory of everything in the latter part of his stellar career. hence the same name for his hollywood biography. In principle, if one had the equations of a Theory of Everything at hand, it would be possible to derive every other natural law from them, including all the laws of physics discovered till now! The hypothetical theory of everything is the biggest unsolved problem in the world of physics at the moment.
I will try to unravel these amazing theories bit by bit in the coming weeks and months, so stay glued! It is gonna be one hell of a ride.
