I don't mean the state of physics in modern times, but the physical nature
of what we call the "present".
Does the "present" have a physical reality outside of conscious perception?
If no one existed to experience time and the present, would the present have
any physical meaning?
It seems to me that without our knowledge or perception of the present, there
would be nothing to determine it. On the other hand, if everyone suddenly
disappeared, it's hard to imagine that it still wouldn't be May 19 2012. But
that would mean that there's something special about May 19 2012. That
with or without us, there is some kind of physical pointer to this point in time.
And I can't imagine the nature of such a pointer.
So possibly time is a continuum, existing all at once, with no physical distinction
between any one point in time and another, as far as one being the "present".
It would only be our perception of that point in time as being "present". And that
would have been the individual perception for each person throughout history.
Or possibly there is no time continuum; there is only the "present", a single "point
in time" which undergoes constant change. We perceive the change as "past,
present and future".
There is of course, the physical quantity of time that shows up in so many physics
equations. The occurance of that term seems independant of "past, present, future"
except for the direction (sign) of the term.
So basically, my question, is there a formal physical definition of "the present"?