Abstract: In this talk, we give a brief overview on the soliton resolution program for the energy critical wave equation and stress the importance of certain radiation lower bounds (also known as energy channel inequalities). Then we show how to prove radiation lower bounds using unique continuation theory, when the initial data is compactly supported (modulo soliton background). We also discuss the challenge in the general nonradial case. Based on joint work with Zhen Lei and Zhaojie Yang