Universal Rate of Time - Yes. Universal Time - No

                                               A metronome sets a universal rate of time. 

Newton's theory of gravitation is commonly viewed to require instantaneous action at distance, with the gravitational force between two material bodies of matter being directed along the line between the instantaneous positions of the bodies, as if they are interacting at distance without time delay.

In the previous post we questioned this view as an illusion resulting from viewing the gravitational potential $\phi$ and gravitational force as the space gradient of the potential $\nabla\phi$, as somehow being generated by "force particles" or "gravitons" exchanged by the bodies, connecting $\phi$ to matter density $\rho$ as the solution to Poisson's equation $\Delta\phi =\rho$.

Instead we suggested to view the gravitational potential $\phi$ as the primary object from which mass was "generated" by the local operation of differentiation with $\rho =\Delta\phi$. In this optics there is no action at distance and there is no instantaneous action requiring simultaneity in time. Everything is local in space and time.

This is a considerable simplification since the notion of simultaneity is very troublesome, as identified by first Poincare and then Einstein leading to the special theory of relativity making common time keeping and simultaneity into an impossiblity.

Inevitably this clashed with Newtonian gravitation with instantaneous simultaneous action at distance, which sent Newtonian mechanics into the dustbin of modern physics based on an incompatible mix of relativity theory for large scale cosmology and quantum mechanics for atomic scales haunting modern physicists with no release or hope.

An alternative viewing of the relation $\rho =\Delta\phi$ thus relieves us from the burden of worrying about the impossibility of simultaneity, and thus may be worth exploring. Doing so we understand that the rate of time, as measured e.g. by a caesium will be the same anywhere in space under the same force conditions, in particular the same under inertial motion with no forces. In other words, there is a universal rate of time, set by a caesium clock, which is the same here as in a far away galaxy.

However, universal rate of time is one thing, and another is universal time, which would require simultaneous start of clocks in different galaxies, which is very tricky because of the time delay in any form of synchronization. But it is possible to a certain accuracy in the near field as shown by GPS which builds on time synchronization.

But with the alternative view, we don't need simultaneity: All action is local and there is no need to coordinate actions at distant places to occur at the same time.

We thus have universal rate of time, which can be useful, but we have no need of universal time, at least not to describe the physics of the world.

Further, there is no longer need of any special relativity theory beyond that of Galileo, since Einstein's special relativity theory was set up to coordinate the readings of different clocks in different inertial systems. We know with Galileo that the clock rate is the same, and we have no need of coordinating time to control simultaneity. The incompatibility of relativity with quantum mechanics then would disappear, which should be viewed as a relief but will probably not be welcomed since suffering from impossibility as become the physicists religion.

In any case, we understand that simultaneity requires time keeping which is a form of book keeping which humans carry out and use,  for navigation, GPS and high-frequency trading et cet, but a book keeping that physics cannot do and doesn't need to do, and which we thus do not need either to describe physics. The World goes around without GPS.

And GPS does not need relativity theory since satellite clocks are continuously synchronized with one stationary master clock on Earth setting universal time rate and local coordinated time around the globe but not in a far away galaxy.