On 12/27/2013 9:55 AM, Edgar L. Owen wrote:
Brent,
Thank goodness, some sanity and clarity!
Yes, you are correct and that is pretty much what I'm talking about. It's quite easy to
understand really. There has to be something happening in Andromeda right now
simultaneously with what's happening here on earth for cosmology to make sense. The fact
that clock times cannot be instantaneously communicated between the two does not negate
that. That common, though admittedly non-communicable, 'right now' is the shared
universal present moment I keep talking about.
Except that it depends on choosing an arbitrary local reference frame. It's not one that
extends across the universe because different parts of the universe are moving (very
rapidly) relative to one-another due to expansion. In GR this implies the absence of a
time-like Killing vector and it is why there is no way to define globally conserved energy
in GR.
Brent
It's quite a simple straight forward and intuitive concept, nothing esoteric at all....
Basic common sense really.....
Thanks Brent, I should have mentioned this myself....
Edgar
On Thursday, December 26, 2013 3:26:28 PM UTC-5, Brent wrote:
On 12/26/2013 8:12 AM, John Clark wrote:
On Mon, Dec 23, 2013 at 2:10 PM, Edgar L. Owen <edga...@att.net
<javascript:>> wrote:
> The proof is simply the fact that the time traveling twins meet up
again with
different clock times, but always in the exact same present moment.
This proves
beyond any doubt there are two kinds of time, clock time which varies by
relativistic observer, and the time of the present moment (what I call
P-time)
which is absolute and common to all observers across the universe.
It's all a question of simultaneity, sometimes observers can agree that 2
events
were simultaneous, and sometimes they can not, it all depends on the
circumstances;
and the amount of disagreement can vary from zero to as large a value as
you'd care
to name. So I don't see why zero is more special or "absolute" than any
other number.
And nothing that happens in the Andromeda Galaxy 2 million light years away
can
have any effect on me for 2 million years, and nothing I do can have any
effect on
Andromeda for 2 million years. So even asking "what are things like right
now on
Andromeda?" is a ambiguous question. Does it mean how things look in my
telescope
when light left Andromeda 2 million years ago? Or does it mean Andromeda 2
million
years in the future when something I do here can make a change there? So
what does
"right now" even mean?
It does have a meaning in most models of cosmology. "Now" is defined by a
comoving
frame in the expanding FRW universe. Operationally it means anybody who
sees the CMB
at the same isotropic temperature is sharing the same "now". But this is
selecting
a preferred frame based on empirical boundary conditions. Edgar refers to
his
P-time as being related to curvature of spacetime, so maybe this is what
he's
talking about, but in spite of my asking several times he hasn't replied.
Brent
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