 Welcome back. The question in front of us quite often is that for the laws of thermodynamics, if there is a proof, the simple answer to this is that there is no proof because these are generalizations. If we were to have proof that means we would have derived these laws using deductive logic but we use generalization and hence we are in the domain of inductive logic. A large number of observations have been made and we have generalized. So why do we believe in these laws of thermodynamics? Well one can say that the belief is because of our faith in the laws of thermodynamics. But the fact is that these generalizations are so good that we have not yet discovered in control. We have not discovered a situation which violates these laws of thermodynamics. And over the years now although thermodynamics has been very properly formulated only in the last century, ideas of thermodynamics have existed for quite a few centuries. And in spite of a large number of observations we have not come across a situation which on the face of it violates any of the laws of thermodynamics. In fact our faith in those laws it is so great that if someone come across an apparent violation of any of these laws we do not conclude that there is something wrong in the laws of thermodynamics. We say that look in the observation in our deduction there must have been some error. So we repeat that experiment with great care with proper measurements and then we realize that yes we were wrong and that apparent contradiction is not really right. And more such things happen more our faith increases and hence we continue to believe in the laws of thermodynamics. Thank you.