DOI: 10.1007/s10701-005-9016-x Foundations of Physics, Vol. 36, No. 2, February 2006 (© 2006) Physics and the Real World George F. R. Ellis 1 Received July 22, 2005 / Published online February 11, 2006 Physics and chemistry underlie the nature of all the world around us, includ- ing human brains. Consequently some suggest that in causal terms, physics is all there is. However, we live in an environment dominated by objects embody- ing the outcomes of intentional design (buildings, computers, teaspoons). The present day subject of physics has nothing to say about the intentionality resulting in existence of such objects, even though this intentionality is clearly causally effective. This paper examines the claim that the underlying phys- ics uniquely causally determines what happens, even though we cannot pre- dict the outcome. It suggests that what occurs is the contextual emergence of complexity: the higher levels in the hierarchy of complexity have autono- mous causal powers, functionally independent of lower level processes. This is possible because top-down causation takes place as well as bottom-up action, with higher level contexts determining the outcome of lower level functioning and even modifying the nature of lower level constituents. Stored information plays a key role, resulting in non-linear dynamics that is non-local in space and time. Brain functioning is causally affected by abstractions such as the value of money and the theory of the laser. These are realised as brain states in individ- uals, but are not equivalent to them. Consequently physics per se cannot caus- ally determine the outcome of human creativity, rather it creates the possibility space allowing human intelligence to function autonomously. The challenge to physics is to develop a realistic description of causality in truly complex hier- archical structures, with top-down causation and memory effects allowing auton- omous higher levels of order to emerge with genuine causal powers. KEY WORDS: Physics; emergence; causality. 1. PHYSICS AND THE EVERYDAY WORLD Physics is the model of what a successful science should be. It provides the base for the all other physical sciences and biology because all objects we 1 Mathematics Department, University of Cape Town, Rondebosch, Cape Town 7701, South Africa; e-mail: ellis@maths.uct.ac.za 227 0015-9018/06/0200-0227/0 © 2006 Springer Science+Business Media, Inc.