Time geography and space–time prism

Time geography is a constraints-oriented approach to understanding human activities in space and time. Time geography recognizes that humans have fundamental spatial and temporal limitations: people can physically only be in one place at a time and activities occur at a sparse set of places for limited durations. Participating in an activity requires allocating scarce available time to access and conduct the activity. Constraints on activity participation include the location and timing of anchors that compel presence (such as home and work), the time budget for access and activity, and the ability to trade time for space in using mobility or information and communication technologies (ICTs). Time geography is a physical not a behavioral theory; it highlights the necessary spatiotemporal conditions for human activities, but does not explain the sufficient events that lead to specific activities. But since these necessary conditions vary by individual and situation, time geography supports an approach to understanding human and environmental systems that recognizes individual histories and the importance of geographic context. Time geography is consistent with some core ideas in fields such as geography, transportation, urban science, social sciences, and environmental sciences. These include an integrated perspective on human and physical phenomena, the need to build macro-level explanations from micro-level processing, and situating human activities within