The laws of physics impose constraints on the activities of intelligent beings regardless of their motivations, culture or technology. As intelligent life begins to extend its potential, information storage, processing and management will become extremely important. It has been argued that civilizations generally are information-limited and that everything intelligent beings do, not just thinking but also economy, art, and emotion, can be viewed as information processing. This means that the physics of information processing imposes limits on what can be achieved by any civilization. In the following I will look at the problems of very large computing systems. They represent the extremes of what an individual being or a culture can become.