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Thursday, March 20, 2014

Denying present time

I have mentioned how Einstein, Greene, and others deny the flow of time. Now also Present time, by Gustavo E. Romero, an Argentina astrophysics professor:
The idea of a moving present or `now' seems to form part of our most basic beliefs about reality. Such a present, however, is not reflected in any of our theories of the physical world. I show in this article that presentism, the doctrine that only what is present exists, is in conflict with modern relativistic cosmology and recent advances in neurosciences. I argue for a tenseless view of time, where what we call `the present' is just an emergent secondary quality arising from the interaction of perceiving self-conscious individuals with their environment. I maintain that there is no flow of time, but just an ordered system of events.
I don't know what to say to this nonsense. First, the present now, and the flow of time, are intuitively obvious and self-evident. Second, our physical theories involved differential equations in time, where the present is used as an initial condition and the flow of time is given by solving the equation.

Thus our beliefs about present time are directly reflected in our physical theories.

Romero writes:
There is no passage of time. There is no moving present. The mere idea of a flowing time simply does not make any sense. An additional problem is that if time flows, it should move with respect to something. If we say that there is a super-time with respect to which time flows, then we shall need a super-super-time for this super-time, and we shall have an infinite regress. In addition, there is no flow without a rate of flow. At what rate does time go by? The answer 1 sec per sec is meaningless. It is like saying that a road extends along a distance of one km per each km that it extends!
You could make this silly argument against anything.
On the physical side, the theory of special relativity seems not to be friendly to the idea of an absolute present, at least in its usual Minkowskian 4-dimensional interpretation. Special relativity is the theory of moving bodies formulated by Albert Einstein in 1905 (Einstein 1905). It postulates the Lorentz-invariance of all physical law statements that hold in a special type of reference systems, called inertial frames. Hence the ‘restricted’ or ‘special’ character of the theory. The equations of Maxwell electrodynamics are Lorentz-invariant, but those of classical mechanics are not. When classical mechanics is revised to accommodate invariance under Lorentz transformations between inertial reference frames, several modifications appear. The most notorious is the impossibility of defining an absolute simultaneity relation between events. Simultaneity results to be frame-dependent. Then, some events can be future events in some reference system, and present or past in another system. Since what exists cannot depend on the reference frame adopted for the description of nature, it is concluded that past, present, and future events exist. Consequently, presentism, the doctrine that only what is present exists, is false.
Others have made this argument,b ut it is wrong. First, the Minkowskian 4-dimensional interpretation of special relativity is due to Poincare and Minkowski, and Einstein had nothing to do with it. Second, it is possible to define an absolute simultaneity relation between events. One can say that events are simultaneous if they have the same proper time since the big bang, just as we do when we speak of the age of the universe. Third, relativity paradoxes have little to do with our sense of now. We have have a sense of now even if someone else has a clock that is not synchronized. Fourth, Maxwell's euqations are differential equations in time, and hence describe a flow in time.

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