1. A computer controlled method comprising: logging a first entity onto a server computer of a persistent virtual environment, by a client computer of the first entity participating in the persistent virtual environment, wherein the client computer comprises a first microprocessor and a first display for presenting the persistent virtual environment to the first entity; responsive to the first entity participating in the persistent virtual environment over a computer network, updating, by the server computer of the persistent virtual environment, a first temporal profile for the first entity to represent an updated presence history of the first entity within the persistent virtual environment; updating, by the server computer, a first coefficient vector responsive to updating the first temporal profile for the first entity, and updating, by the server computer, a second coefficient vector responsive to updating a second temporal profile for a second entity participating in the persistent virtual environment, wherein a second client computer comprises a second microprocessor and a second display for presenting the persistent virtual environment to the second entity, wherein the first and second coefficient vectors comprise coefficients to one or more basis functions, wherein a respective basis function corresponds to a specific time interval in the presence history, and wherein a respective coefficient corresponds to a general least-squares fit value to the one or more basis functions for the specific time interval; generating, by the server computer based on the first and second coefficient vectors, a third temporal profile which indicates a temporal similarity of the first and second entities; performing, by the server computer, a predictive function that provides a strength of prediction and a probability value associated with a future time during which the first and second entities are likely to both be virtually present in the persistent virtual environment based on the third temporal profile that indicates the temporal similarity between the first and second coefficient vectors, wherein the strength indicates a confidence level associated with the probability value of the prediction; sending, by the server computer, the future time, the probability value, and the strength of prediction associated with the probability value to the client computer; and presenting, by the client computer on the first display, a representation of the future time, the probability value, and the strength of prediction associated with the probability value that are derived from the predictive function.