Entropy is important in philosophy of science,but some fallacies originate from the misunderstanding entropy increases.The basis of thermodynamics is the statistics and its basic principle of statistical independence.We proposed possible entropy decrease due to fluctuation magnified and internal interactions in isolated systems,and discuss this possibility of various aspects on science and nature.Further,we derive quantitatively a total formula of entropy change for universal evolution of any natural and social systems,and discuss entropy decrease in economics and social sciences.Entropy change is a testable science.As long as we break through the bondage of the second law of thermodynamics,the rich and complex world is full of examples of entropy decrease.We believe world is not pessimistic always.