I did explain with an example.

I told you that gravity cause spacetime to curve.

That is not an example, that is the topic. I have no faith in your authority as a physicist. And you yourself said that Einstein was an eternalist.

I would say it is logically impossible for something to have no speed, and yet be dynamic.

I would say it is logically impossible for something to have no speed, and yet be dynamic. — hypericin

What if it's jumping around in a totally inconsistent manner, one moment here, the next moment over there, then somewhere else, etc.. How could this thing have any speed?

Are there dynamic abstractions...really??

You can measure it's average position, the rate of jumping, it's average instantaneous speed between jumps... I'm talking about speed in the sense of rate of change.

Another reason time can have no speed: change in time over time makes no sense.

One could view time as a product of extension, or physical change. A physical change which is going to happen anyway and does happen, but an unfortunate consequence of this, depending on your point of view, is the presence of time.

Any dynamic process, a chemical reaction for example, has a speed. "Rate", if you prefer.
Time, as you point out, cannot have a speed/rate.
Therefore, time cannot be a dynamic process. — hypericin

Processes (you don't need the word "dynamic"--processes are necessarily dynamic) have a speed relative to other processes. That includes time, because time is just process.

You can measure it's average position, the rate of jumping, it's average instantaneous speed between jumps... I'm talking about speed in the sense of rate of change.

Another reason time can have no speed: change in time over time makes no sense. — hypericin

Change in the rate of change is observed empirically, it is known as acceleration. You may be right, it may not make sense logically, and that's why physicists have found that it is a difficult subject. It is similar to the concept of "becoming", which doesn't make sense logically. It requires something in between two describable states, and this forces an exception to the law of excluded middle. But when things appear to disobey our laws of logic, this does not mean that they are unreal, it just means that they are not well understood.

Are you familiar with Aristotle's distinction of two types of change? There is change of place, locomotion, and change to an object. The latter is a change which is not a change of place. There is nothing to necessitate that change to an object must be consistent in the way that you describe. It is only when that object is related to another object, as the cause of that change, or as a standard of measurement for a "rate of change", that a change of place is established, and the consistency which you refer to is developed.

How can Process Itself have a speed relative to actual processes?

But I am arguing that time has no absolute speed. We can easily accept that motion can have only a relative speed, this accords more or less well with our intuitive understanding of motion. But with time, it is much more difficult. It clashes with the intuitive notion that time is plodding forward at a constant rate.

So the problem remains: there are at most minute measurable differences, in most cases, in the relative speeds of time. But there is no such thing as an absolute speed of time. And without a speed, how can time, as we understand it, operate at all? — hypericin

What you are dealing with is that change or flux can only be measured with absoluteness if we can establish some absolute backdrop of stasis or a complete lack of change. And in the end, we can't find such an absence of dynamism. We can only find a relative absence to construct our desired backdrop for measurement.

So our notions of time are an attempt to arrive at an image of "least change". That is is why you find yourself talking about a Newtonian model of time as a spatialised dimension - a line with points. And then why you worry about why motion along this temporal line should be itself constant and not variable in its speed.

But you give your own answer already on that. If everything was "sped up" or "slowed down" by time changing its speed, it would make no difference. It would be the same as if the speed of time was constant anyway. And so, the whole question of "what speed is time moving at" can be seen as irrelevant. Treating time as a Newtonian dimension is already as simple as it gets. To have a global dimension that is eternally there in always the same fashion is already the least amount of change that can be conceived.

This should be apparent from Newton's own classical laws of motion. Constant linear motion or constant angular momentum are inertial - a form of change that is not really a change in dynamics. A rolling ball can roll forever at the same speed. This is a consequence of time being a "statically existing" global symmetry. A realm of objects in eternal inertial motion is already as rock-bottom unchanging as you are going to get.

But Newtonian dynamics has been found to be too static even with its already irreducible degree of "constant change". Relativity required a more dynamical picture on the large and cold scale, quantum mechanics required it on the small and hot scale.

So time is just the way we talk about measuring change. And that in itself involves establishing some general backdrop of relative "no-change" against which we can then measure the other thing of some particular or local change.

This is why the very notion of time appears to be based on the "necessary self-contradiction" of being a static or unchanging backdrop thing. It is the fixed container of everything that changes.

But even with Newtonian time, critical aspects of the dynamics of things are made part of the global picture. Inertia - the kind of motion that is constant - is a universal property of masses. So Newtonian physics simplified our notion of time in putting the cause of constant motion "elsewhere" in its physics. But as we moved towards the kind of physics that could unify our notions of spacetime as a container, and matter as its contents, inertial motion came back to haunt everyone. Time had to be reimagined in the more dynamical fashion that could underpin relativity and quantum mechanics.

How can Process Itself have a speed relative to actual processes? — hypericin

I don't understand the apparent distinction you're making. There are only actual processes. "Process itself" is actual processes. "Process itself" makes sense in that you're just talking about the fact that something is changing or is in motion, and you're not talking about specifically what is changing or is in motion, but "process itself" only obtains via actual processes. The idea of processes that aren't actual (that is, the idea of them existing or obtaining somehow) makes zero sense in my opinion.

Thanks for the stimulating reply. I am still stuck though.

A realm of objects in eternal inertial motion is already as rock-bottom unchanging as you are going to get.

We can imagine space as a 3D euclidean space, divided into a mesh of invisible little points or cubes. Motion then has an absolute meaning, as moving with respect to this mesh.

But, this is a fiction. Motion is meaningful only relative to other frames of reference. That is fine, as objects are distributed throughout space, with their own separate velocities. But, if we were to claim that the *entire* universe is moving at some velocity, then, without this lattice of cubes to move against, this is exactly equivalent to saying that the universe is completely stationary.

But what if we treat time as a 1D line, analogous with space? Then, unlike with space, every object is at the same point, and moving through time at the same rate. Which, unless you imagine absolute points along this 1D line, analogous to the lattice of cubes in space, is also like saying that every object is motionless in time. Or, if you invoke relativity, then objects are only moving in time to the degree that relativistic effects are observed.

If we aren't moving through time, then how did I seem to start this at time t, and arrive at t + 20 seconds when I finished? Do we need the imaginary points, or some other unobservable, "unchanging backdrop thing"?

Or can we dispense with time altogether? Everything is just process, at rates relative to each other and nothing else, in an eternal present? I am ignorant as to whether physics actually requires an ontologically existent time, as opposed to a formal notion which makes the equations work.

When you said "time is just process.", I took that to mean that you regard time as somehow the abstract essence of processes. If not that, then what?

I took that to mean that you regard time as somehow the abstract essence of processes. — hypericin

Yeah, in a way, but that doesn't mean that it's not actual. It's process in general, not any specific process (like say just a clock ticking). Or in other words, it ranges over all actual processes.

Then how can a range over all processes have a speed relative to specific processes?

When I say it's not any specific processes, I'm saying that it's not just some subset of specific processes, while not being other processes. For example, someone might think it's the process of a clock ticking, say, but not a bird in flight. I'm saying it's both. It's every process, or the process part of every process--which just means that it's not the "feather" part of a bird in flight, for example, but the changing relations that amount to being in flight.

Hence "Processes have a speed relative to other processes. That includes time, because time is just process." In other words, each one of those processes is what time is. Every single process. They have speeds relative to other processes because we simply compare one to the other. "The bird flaps its wings x times per click of this clock" for example. That's what the speed of processes is--that comparative relation.

We can imagine space as a 3D euclidean space, divided into a mesh of invisible little points or cubes. Motion then has an absolute meaning, as moving with respect to this mesh. — hypericin

But you have then added the extra thing of a change in location to your static grid. So now there is something extra in the this grid world that is not fixed to a location. And its position can change in regard to location in a way that you would feel moved to describe as where it was "previously", where it is "now", and where it could be in the "future".

So you started with a spatial grid and smuggled in notions of matter and time to create a model of a world of objects in motion (or not, if their positions are seen to be unchanged during the time that other objects do change their position).

But what if we treat time as a 1D line, analogous with space? Then, unlike with space, every object is at the same point, and moving through time at the same rate. Which, unless you imagine absolute points along this 1D line, analogous to the lattice of cubes in space, is also like saying that every object is motionless in time. Or, if you invoke relativity, then objects are only moving in time to the degree that relativistic effects are observed. — hypericin

But that is just to treat time as a further spatial dimension. If time actually was just like that, we should be able to travel backward in time with the same ease we move forward. And we should be able to remain at rest in time.

So while a spatialised representation of time is useful, it doesn't seem true in a deep way.

What physics is working towards is a thermal model of time which accounts better for its apparent character. So time now becomes the rate at which the contents of the Universe in general are cooling as - spatially - the Universe expands. There is an entropic curve that the entire Universe is running down at a general rate.

So now we can look at the most general material feature of the Universe - the cooling and spreading bath of cosmic background radiation. Everywhere, the temperature of the CMB is falling at the same rate. It is changing at the same speed. And this now gives a concrete backdrop of steady change against which we can measure different local rates of change.

It defines simultaneity in terms of a standard temperature. Right "now" the cosmic time is 2.725 degrees above absolute zero. And there is a thermal arrow that points from when the Universe was hotter to when it will be even cooler still.

So time is how we can measure change in terms of whatever it is that we can find as not changing. And time also has some intuitive features - like a locked-in forward direction, and a universality in terms of there being some common "now" where everything in some sense stands in the one spot - that a spatialised Newtonian model is not good at representing.

Therefore we need better ways of modelling time that produced these other features in a more intuitive fashion. Talking in terms of temperature rather than location is a way to do that. Even if we are standing still, we can see that a process of entropification means we are getting older and colder at the same general rate as the entire Universe.

Or can we dispense with time altogether? Everything is just process, at rates relative to each other and nothing else, in an eternal present? I am ignorant as to whether physics actually requires an ontologically existent time, as opposed to a formal notion which makes the equations work. — hypericin

Don't forget that the rate of change we care about most is that of massive objects. Light travels at only its one speed (and so, for lack of comparison, radiation is pretty "timeless"). Massive objects are free to move at any speed between rest and c. So massive objects have the kind of variety relative to a pair of absolute bounds on motion that lets us talk about them moving at different rates in comparison to this backdrop difference.

So when you are talking about the speed of mass x, you are saying it is y times faster that being at rest, and z times slower than being at c. That is why masses appear to move "inside" time. There is both an upper and lower absolute bound that between them define a range of meaningful speeds.

Mass always thus exists somewhere on a spectrum of speeds. There is always a faster and a slower from wherever they are now.

Or at least this is the case for the Universe as it is thermally right "now" - a Universe that is largely in its classical regime being neither so hot and small that it is a Big Bang bunch of thermal fluctuation, nor so cold and large that it is just a "red-shifted to buggery" Heat Death sea of thermal fluctuations once again.

I don't understand the conflation of the measurement of time and time itself. CBR might be a universal clock. But does it make sense, in response to the question "What is Time?", to point to a clock? Is there any justification in believing that time itself would stop if the universe were to stop expanding?

But does it make sense, in response to the question "What is Time?", to point to a clock? — hypericin

Well if you believe a clock can actually measure time, then surely that answers your own question?Whatever a clock is, it represents the way you already conceive of time.

It defines simultaneity in terms of a standard temperature. Right "now" the cosmic time is 2.725 degrees above absolute zero. And there is a thermal arrow that points from when the Universe was hotter to when it will be even cooler still. — apokrisis

That's a damn cold universe! If this is the current temperature, and the passing of time is the universe cooling, and the temperature limit is absolute zero, then there must be a relatively small amount of time left for the universe.

Let me guess, it never reaches absolute zero, or in other words it takes an infinity of time to get there.

I was thinking that in these physical models time need not be short, if it's long then the matter can get on with its stuff regardless. If time just allowed matter some space(in time) matter would just get on with it anyway. Perhaps time is something which we as observers can't do without, but matter can.

Well if you believe a clock can actually measure time, then surely that answers your own question?Whatever a clock is, it represents the way you already conceive of time. — apokrisis

I would say that the clock actually IS time, just as all processes (all change/motion) are.

Yep. Except the entropic clock ticks in logarithmic units, not linear. It's cooling is an asymptotic curve.

So if the first tick was a second, the second tick is 10 seconds long, the third 100 seconds long, and so on, if you get my drift. Thus the last tick will last for bloody ever.

Remember the geometry that underlies this view. We are talking about an expanding sphere of gas. So the temperature or energy density drops fast if the sphere is an inch wide and grows by another whole inch. But once the sphere is a mile wide, growing an inch makes very little difference.

So to achieve constant temperature drop, each tick of the entropic clock must be exponentially longer than the last.

Well, I would say then, that time is passing incredibly slow right now, if the temperature is only 2.725 degrees above absolute zero, because when time started passing, the temperature must have been extremely high, in comparison.

Doesn't this seem extremely absurd to you, that time would all of a sudden start passing extremely fast, and then slowly slow down? What kind of reverse acceleration is that, something that all of a sudden starts extremely fast, then slows down? Even if you pack a huge amount of power into a small thing, then let it go, like a wind up toy, that thing has to accelerate to get up to top speed, before starting to slow down. How is time supposed to get up to top speed, before starting to slow down?

That seems over-broad though, like saying that "Time is the universe." What isn't a process, or a part of one?

A thermometer measures temperature and perhaps represents a conception of temperature, but in no way can you say a thermometer *is* temperature.

That seems over-broad though, like saying that "Time is the universe." What isn't a process, or a part of one? — hypericin

I don't see there being a requirement on a broadness scale. The only requirement seems to be that something is right. And this is right. Process--change/motion, is what time is.

What isn't process? Relations in general (though of course relations are often processual--but they're not always), the material changes/moves with respect to other material, structures that are not in process, although that may just be an abstraction.

Even if you pack a huge amount of power into a small thing, then let it go, like a wind up toy, that thing has to accelerate to get up to top speed, before starting to slow down. How is time supposed to get up to top speed, before starting to slow down? — Metaphysician Undercover

Yep, the Big Bang exactly represents the situation of a wind up toy. Your argument is devastating.

If time is every process in the universe, then how is a single number sufficient to tell us the current state of time?

then how is a single number sufficient to tell us the current state of time? — hypericin

You mean how is looking at 4:00 on your watch, say, sufficient to tell you that it's 4 o'clock? Maybe I'm misinterpreting your question though.

But you know that it being 4 o'clock is just a convention in your locale, right?