In this book, the author introduces an alternative perspective to understand thermal phenomena, the concept of entransy and its relevant principles, applications and extensions, which have been widely used in the analyses and optimizations of many transport processes. The scientific significance and application value of the theory have been clearly demonstrated. The theory is inevitably questioned, and there are even accusations that are not academically valid. These controversies are also introduced and discussed comprehensively.This book is an introduction to the entransy theory; the author...