What Do We Expect to Learn from Very High Energy Cosmic Ray Observations?

Abstract

By a short tour through the exciting field of very high-energy and ultra high-energy cosmic rays studies, a brief review is given about the current questions approached, in particular by the KASCADE experiment and the Pierre Auger project. The present status of the investigations of the knee region of the cosmic ray spectrum by KASCADE is presented and open problems are discussed.

16 pages, Presented at the XVII Mazurian Lakes School of Physics "Growth Points of Nuclear Physics A.D. 2001", September 2--9, 2001 Krzyze, Poland. To be published in Acta Physica Polon.B