What is time? According to Connes and Rovelli - Part 4
Connes and Rovelli continue:
In this paper, we consider a radical solution to this problem. This is based on the idea that one can extend the notion of time flow to general covariant theories, but this flow depends on the thermal state of the system.
Now, just think about it: what a radical solution! I propose even more radical and simpler solution: to extend the notion of time flow to general covariant theories, but this flow depends on the time flow!
More in detail, we will argue that the notion of time flow extends naturally to general covariant theories, provided that: i. We interpret the time flow as a 1- parameter group of automorphisms of the observable algebra (generalised Heisenberg picture); ii. We ascribe the temporal properties of the flow to thermodynamical causes, and therefore we tie the definition of time to thermodynamics; iii. We take seriously the idea that in a general covariant context the notion of time is not state-independent, as in non-relativistic physics, but rather depends on the state in which the system is.
"We interpret the time flow as a 1- parameter group of automorphisms of the observable algebra (generalised Heisenberg picture)" This is a radical solution indeed! Except that a) it is nothing new, and b) it applies only to closed system - while our universe seems to be an open system - otherwise nothing will ever ever ever happen - except of Cointon’s time evolution. No bit of information will ever be transfered or recorded. It is a radically dead world! We ascribe the temporal properties of the flow to thermodynamical causes, and therefore we tie the definition of time to thermodynamics. And what are thermodynamic causes ? Something related to heat? And what is heat? Is it related to chaotic motion? And what is motion? Is it, perhaps, change of a state with time? Wait, But what is time? We take seriously the idea that in a general covariant context the notion of time is not state-independent, as in non-relativistic physics, but rather depends on the state in which the system is. Now, question, is state a subjective or an objective property? There is a whole lot of arguments in the foundations of quantum theory that support the idea that there is no "objective state," and so there is no "reduction of the wave packet" - because what is being reduced, what jumps, is knowledge - which is subjective (or partly subjective). If so, then the flow of time is also subjective? Connes and Rovelli seem not to notice a serious problem here. Moreover, if state is objective, and if time is what they say time is, then, because our universe is evidently NOT in a thermodynamical equilibrium, therefore time does NOT flow in our universe. A radical concept indeed!
