Doubts I Have

This past weekend I was wondering about our ability to estimate time, how the hell can we do that? Do we have an internal clock somewhere? How does it tick?

We all have somehow a notion of time. Good musicians are able to keep a perfect tempo, respect the music pauses and respect the notes length. Dancers synchronize their body movements with the rhythm of the music. The most evident examples of our internal clock are related with music but a notion of time might be necessary for all sort of things. When a volleyball player receives a pass he needs to decide the perfect timing for him to jump and hit the ball. He might have a very good idea of what are the dynamics of a falling object (he has seen it many times) and together with an internal clock he would be able to predict the ball’s trajectory and decide the best instant for him to jump and meet the ball. There are , however, other options to achieve this that don’t require the use of an internal clock. For example, the volleyball player could analyze at each instant the ball’s state history and decide if there would be a better instant to jump in the future or not based on past experience, he would then jump when his prediction said that there wouldn't be a better instant for him to do it. This last method seems to be very inefficient method in terms of memory and ability to generalize. It’s a very hard problem to be able to learn a value for each state in the huge state space, composed by the history of the ball state, and it seems even harder to reuse this learned knowledge in a similar situation but with slightly different conditions (e.g. playing with wind). Having an internal clock would certainly simplify the learning and generalization of the task so we will assume for now that we do have this internal clock. This assumption raises another number of questions: do we only have one internal clock or do we have many and we apply them to different tasks? how precise is this clock? is the clock delayed or in advance by a fixed amount of time? is the rate of time different? what is the behaviour of the error of this clock?