Joe Boswell in Scientia Salon:
Adam’s Opticks: Hi Lee, central to your thesis as outlined in Time Reborn, and in its recent follow-up The Singular Universe (co-authored with Roberto Mangabeira Unger) , is a rejection of the “block universe” interpretation of physics in which timeless laws of nature dictate the history of the universe from beginning to end. Instead, you argue, all that exists is “the present moment” (which is one of a flow of moments). As such, the regularities we observe in nature must emerge from the present state of the universe as opposed to following a mysterious set of laws that exist “out there.” If this is true, you also foresee the possibility that regularities in nature may be open to forms of change and evolution.
My first question is this: Does it make sense to claim that “the present moment is all that exists” if one has to qualify that statement by saying that there is also a “flow of moments?” Does the idea of a flow of time not return us to the block universe? Or at the very least to the idea that the present moment represents the frontier of an ever “growing” or “evolving” block as the cosmologist George Ellis might say?
Lee Smolin: Part of our view is that an aspect of moments, or events, is that they are generative of other moments. A moment is not a static thing, it is an aspect of a process (or visa versa) which generates new moments. The activity of time is a process by which present events bring forth or give rise to the next events.
I studied this idea together with Marina Cortes. We developed a mathematical model of causation from a thick present which we called energetic causal sets . Our thought is that each moment or event may be a parent of future events. A present moment is one that has not yet exhausted or spent its capability to parent new events. There is a thick present of such events. Past events were those that exhausted their potential and so are no longer involved in the process of producing new events, they play no further role and therefore there is no reason to regard them as still existing. (So no to Ellis’s growing block universe.)