MATTER IN EXTREMELY INTENSE LIGHT FIELDS

During the last few years, great progress has been made in the generat ion of extremely short, intense laser pulses. The electric-field stren gth in the focus of a laser beam reaches Values comparable with or eve n much greater than atomic fields. Under these circumstances the inter action of light with matter can no longer be regarded as a weak pertur bation, in contrast to most previous situations. In this article an at tempt is made to describe this new development and to present some ill ustrative examples from different areas of physics. The physics of ext remely high intensity light is interesting not only from the point of view of fundamental science but also because of promising applications , in particular new possibilities of generating very short X-ray pulse s.