Several e-mails were exchanged between Prof. Schick and I (YS) about our views of the periodic heating method. Prof. Schick has been working on the periodic heating method extensively and organized Lähnwitzseminar known as the leading conference in this field. I believe that the most suitable person gave contribution to this special issue. I hope that the readers will enjoy this discussion and I thank for the recent surprising development of the communication technology that enabled this discussion.