In this work he came up with the idea that some galactic civilizations would be perhaps millions or billions of years ahead of us, and created the Kardashev classification scheme to rank such civilizations.
做这个工作的同时，他猜想有些银河文明有可能比我们先进几百万甚至几十亿年，为了给这些文明分等级，他创造了卡尔达肖夫分类法。