What is the smallest thing in the universe? What is the biggest? Answer of these simple question can not be given by our common sense or classical mechanics. For the tiniest we have to take the help of Quantum Mechanics and for the biggest, General theory of Relativity.
From the analysis of 7 year of data collected by WMAP Satellite physicists found that the observable universe is about 93 billion light years across. Inflation theory suggests that the universe is 3×10^23 times larger than the observable universe. It is estimated that at least the universe is 250 times and at the highest it is ((10^10)^10)^122 times larger than the observable universe. It was found that the universe became 10^50 times larger than initial one at the time of inflation. Jhon Wheeler of Princeton University found that the smallest distance is 10^(-33) ( which is called plank length) analyzing Einstein‘s equations. The radius of an isolated neutral atom is between 30 to 300pm which is 1000 times larger than the radius of nucleus( 1 to 10 fm ). Radius of a quark is smaller than 0.43×10^(-16)cm ( about 2000 times smaller than a proton radius).
At the time of creation the gravitational force was so enormous that we have to take account of general relativity. On the other hand size of the universe was so small that we have to take the help of quantum mechanics. So, to know the origin of the universe we have to unify the two great theories which deals with totally opposite things. The most debated candidate of unification is String Theory. String theory suggests that you and I work differently because the strings that make us vibrates in 10 dimension at different frequencies. Isn’t that wonderful? I think it is.