The Question of What is Now?

     One of the cool things about physics is that every now and then a question comes up and it makes you go "what a fascinating topics for physics to look into and I'm surprised I've not heard more about it".  One of those moments happened earlier this year when in the March 2014 issue of Physics Today there was a commentary by N. David Mermin entitled "What I Think About Now".  It is a fascinating article and when I read it I wonder about that I know I've thought about my moments of Now but never really thought about what the physics meaning of Now means.  I'm capitalizing Now in the ways Mermin does to point out the Now that is being discussed.  Now being your personal conscious feeling about your Now.   Physics treats  objects as just things that don't perceive a Now.  Objects are a rock or baseball or a proton..  Physics tries to understand what these objects are made of and the forces that they interact with and the understanding of these forces.  The objects perception of Now then gets into the area of consciousness and self awareness.     In Mermin's article he mentioned about Einstein's feeling of the Now which is the following:

Einstein said that the problem of the Now worried him seriously. He explained that the experience of the Now means something special for man, something essentially different from the past and the future, but that this important difference does not and cannot occur within physics. That this experience cannot be grasped by science seemed to him a matter of painful but inevitable resignation. ²

This would seem to say that Einstein thinks physics cannot describe the Now as experienced by the individual.. The personal, conscience, self awareness of  Now..  It reads to me that Einstein didn't think that consciousness could be understood by science. Interesting.  The idea of the Now in physics is fascinating.  In the September issue of Physics Today there are third letters about Mermin's  Now commentary they are here, here, and here.  The last letter has a reference to an arxiv paper about the physics of the Now.  Finally there is a reply by Mermin to these letters.  

     There seems to be two Nows.  One the physics Now of a point in spacetime described by its coordinates i and the worldline that the objects experiences in spacetime as described by the laws of physics.  Very impersonal and sounds like the stuff that physicists do. The other is the personal, psychological, conscience Now that physicists are beginning to seriously study as mentioned in an earlier post entitled Quantum Consciousness.  

    The personal Now has to do with self awareness.  Self awareness is an emergent process of your consciousness.  It is something your consciousness develops with time./Somehow and sometime, which is not understood, your brain and body become conscious but not self aware.You then do not know the concept of Now until you are self aware.  Because Now is a subjective experience of your  self aware consciousness.  Now becomes the present state in spacetime of your self aware consciousness.  You as a person.don't know of Now until that self awareness turns on in your consciousnesses.  Then you have a feeling of time.  That the world is changing and that you perceive that change and that is what we call rime or the flow of rime.  So your subjective idea of Now starts when you become self aware.  This is probably obvious to everyone..