What is time?

[Overdog]

Originally Posted by modest

While I understand how an investigation into the nature of time can stray into issues of ontology, hopefully we can keep that in the context of Craig's thread here "what is time".
~modest

That was where I was heading...

So the fundamental question is does time exist outside and independently of the lens through which we view it?

[Overdog]

I think most would agree that it does, and Modest's post with respect to the relativistic view shows it doesn't make sense to think of it independently of Space. It appears to be a fundamental property of the Universe, as we know it.

[ldsoftwaresteve]

Originally Posted by Overdog

That was where I was heading...

So the fundamental question is does time exist outside and independently of the lens through which we view it?

I say no, it doesn't. It's a function of how we perceive and deal with change and how we relate one change to another.

And if that is an accurate description of the world outside of the lens viewing it, then the concept of time resides inside of the lens and is a coping mechanism.

Whatever it is that drives change, drives it the same simultaneously throughout the universe and it is extremely consistent. It is that consistency that allows mathematics to work and which also allows us to express one change in terms of another.

[Overdog]

Originally Posted by ldsoftwaresteve

I say no, it doesn't. It's a function of how we perceive and deal with change and how we relate one change to another.

And if that is an accurate description of the world outside of the lens viewing it, then the concept of time resides inside of the lens and is a coping mechanism.

Whatever it is that drives change, drives it the same simultaneously throughout the universe and it is extremely consistent. It is that consistency that allows mathematics to work and which also allows us to express one change in terms of another.

I'm having trouble grasping what you are saying.

Would you also say that Space has no independent reality as well?

Are you defining time as "Whatever it is that drives change..."?

[Doctordick]

Originally Posted by Overdog

It appears to be a fundamental property of the Universe, as we know it.

The problem with that statement is the fact that it is, nevertheless, an assumed property and not a demonstrable fact. I am starting a new thread stating my concern with the duplicity currently surrounding the common concept of “The Philosophy of Science”. I think this is a very serious issue and worthy of careful thought which is something which might interest you since you seem to take these issues seriously.

Have fun -- Dick

[Overdog]

Originally Posted by Doctordick

The problem with that statement is the fact that it is, nevertheless, an assumed property and not a demonstrable fact. I am starting a new thread stating my concern with the duplicity currently surrounding the common concept of “The Philosophy of Science”. I think this is a very serious issue and worthy of careful thought which is something which might interest you since you seem to take these issues seriously.

Have fun -- Dick

Thanks, Doctordick, I look forward to the discussion. I have been following your other threads with interest, but the math is way beyond me. I try to comprehend as best I can. It was my fascination with one of your threads that brought me to Hypography in the first place!

Yes, an assumed property and an arbitrary definition as well, but one such that the equations posted earlier by Modest and AnssiH work to describe what we observe.

Those expressions suggest that a "working" definition of time, whatever we assume about it, is a variable dependent on one's frame of reference, which as I understand it, is one's position and velocity in space. It seems logical then that if time depends on frame of reference, and frame of reference depends on space, that time depends on space.

Of course you know all this...my only reason for saying it is to clarify that what I'm aiming at here with the notion of time is simply a "usefull" definition.

But I believe your point is that we are simply pointing to the variable "T" in the expressions and calling it time?

[modest]

Originally Posted by AnssiH

Modest, in case you are wondering, that has got very little to do with the math of relativity. It just has to do with what kind of reality that math implies (or what sorts of realitites are still possible behind that math, many of which are not very evident from the math directly)

Agreed. Allow me to quote Dr. Kelly Ross (philosophy of science professor):

Just because the math works doesn't mean that we understand what is happening in nature. Every physical theory has a mathematical component and a conceptual component, but these two are often confused. Many speak as though the mathematical component confers understanding, this even after decades of the beautiful mathematics of quantum mechanics obviously conferring little understanding. The mathematics of Newton's theory of gravity were beautiful and successful for two centuries, but it conferred no understanding about what gravity was. Now we actually have two competing ways of understanding gravity, either through Einstein's geometrical method or through the interaction of virtual particles in quantum mechanics.

Nevertheless, there is often still a kind of deliberate know-nothing-ism that the mathematics is the explanation. It isn't. Instead, each theory contains a conceptual interpretation that assigns meaning to its mathematical expressions.

Originally Posted by AnssiH

The underlying "ontological" reality behind "time dilation" can be seen in many different ways,

Sure. There may well be no limit to variations on how it’s ”seen”. But, how many interpretations of space and time can derive time dilation, agree with all known observation, and be used to predict the future evolution of a system? It would not make good sense to me if the answer was greater than one in our one universe.

Originally Posted by AnssiH

though all different views can agree it is predictionwise quite valid to describe the situation as "Tommy ages more slowly".

We can safely take it one step further and say we know how much slower Tommy ages. This situation was tested experimentally and the equation in my last post proven empirically in 1977. Bailey, Borer, and Combley-‘77 tested time dilation of muons traveling in a circular path at relativistic speeds to very high accuracy.

In terms of deriving relativity there are many options. The consistency of the speed of light between inertial frames is reflective of the more fundamental postulate that all laws of physics are the same in all inertial frames. More fundamental would be deriving from Lorentz covariance which ultimately boils down to the single postulate of Minkowski spacetime. You can start at the 'geometry' of Minkowski spacetime and end up saying exactly how much older Sally will be than Tommy.

So, I look at this situation and say that space and time as described by Minkowski are the axiomatic reality of our universe. Being axioms, they cannot be directly tested; and that is an interesting conundrum for a student of philosophy. But a physicist or mathematician will acknowledge the entirety of physics that is built on that axiom as both internally consistent and in agreement with observation which verifies the axiom beyond a shadow of a doubt.

Originally Posted by AnssiH

E.g. are Sally and Tommy passing through "time dimension" of "relativistic spacetime" in real ontological sense, or is spacetime just mental construction and the actual ontology is perhaps closer to, say, all natural processes in Tommy's situation are moving more slowly than in Sally's (rather like clock slowing down under stress) ...or is the root of relativistic time description found from our methods of defining entities in unknown data. To investigate that route, you might want to take a look at that epistemological analysis.

Here I think you’re trying to describe different interpretations or perhaps foundations for relativity. Some things like “just mental construction” I understand and would be able to refute. Other things like “our methods of defining entities in unknown data” are completely lost on me. I will say: the relationship between space and time that allows relativity to work is very well defined. To reinterpret time or space and end up deriving relativity which agrees with observation would be something quite amazing.

Originally Posted by AnssiH

I was bringing up relativity of simultaneity instead of time dilation directly because that offers a fairly simple route to considering what ontological implications relativity makes on time and associated components;

Really, it’s all the same. The difference is between Galilean absolute time and Lorentz variable time. This is true regardless of which particular aspect of relativity you want to look at. The universe would work differently depending on which type of time it kept (I should say more properly - how the universe keeps time). By observation we know it isn’t Galilean or Newtonian absolute time but is truly relative in a way that follows the Lorentz transformations.

~modest

[ldsoftwaresteve]

Originally Posted by Overdog

I'm having trouble grasping what you are saying.

Would you also say that Space has no independent reality as well?

Are you defining time as "Whatever it is that drives change..."?

To the extent that 'nothing' exists as something, Space does have independent reality. But if it's truly nothing, then it would be more like a rainbow, i.e. something we attach identity to but which is really an illusion caused by how our perceptive ability functions.

I'm coming at the concept of 'time' as an effect of a conscious mind aware of change, not as the cause of change.

If we assume 'time' is the cause of change, we might make ourselves blind to the actual nature of change. It's just possible that the way we use time in our worldviews today stops us from seeing change in a different and more accurate light.

[ldsoftwaresteve]

Modest:

So, I look at this situation and say that space and time as described by Minkowski are the axiomatic reality of our universe. Being axioms, they cannot be directly tested; and that is an interesting conundrum for a student of philosophy. But a physicist or mathematician will acknowledge the entirety of physics that is built on that axiom as both internally consistent and in agreement with observation which verifies the axiom beyond a shadow of a doubt.

Beautifully expressed Modest. If, however, the accuracy of our observation is not 100%, then there still remains a shadow of doubt on all of our beliefs. Until we can see the underlying activity of particles and verify our current models by seeing them in action, there will be at least some shadow of doubt.

[AnssiH]

Originally Posted by Overdog

Ok AnssiH, I thought I understood the metaphysical sense in your use of the word "Ontology" in your previous post, which was why I said "I have to agree..."

So you are saying it all depends on your view, or "model" of reality, and that there may be different, yet equally valid, views of reality.

Did I get it right?

I would word it "...and it is always possible to model any system in many valid ways".

Hell, I have no idea how I see it...

Well, maybe start by spending some time thinking about what could be the real ontology behind a non-absolute simultaneity as it exists in special relativity, and see where all the different options take you. Just to open up your mind from the clenches of your worldview

Originally Posted by Overdog

Modest's post with respect to the relativistic view shows it doesn't make sense to think of it independently of Space. It appears to be a fundamental property of the Universe, as we know it.

Relativity is a model where space and time get somewhat entangled to each others (because of what I explained regarding how a different notion of "simultaneity" affects the supposed geometry of a "moving" object). It is only if you are talking about relativity when you can say "it doesn't make sense to think of time independently of space".

But note that it is quite possible to build models where time and space do not get entangled that way. We do not know what is the reality lurking behind relativity.

Let me give you another specific example of ontological unknown. At the times of Newton, many people would have been inclined to think that quite undeniably there is such a force as gravity; we see the effect of that force every day.

It would have been more objective to just say we see something that we explain by such a defined concept as "gravitational force".

As you are probably aware, in relativity - when space and time are defined little bit differently - there is no such "force" at all. What we call "gravity" is seen in quite a different light, rather like a side-effect of spacetime, or how we have defined spacetime to behave near "matter". This still should not be seen as ontologically real even though the model works. We still see something, and we explain it by having defined time and space in such and such manner.

Originally Posted by Overdog

Would you also say that Space has no independent reality as well?

I know I would.

The concept of space is meaningless without defined concepts like, "distance" (between things we have defined); the idea of "location" is meaningless unless we relate it to defined "things". And dimensionality hinges on a definition; the exploitation of that fact allows us to build valid models where reality is described with different number of dimensions than 3. (Relativistic spacetime can be seen as 4 spatial dimensions, in the sense that it is possible to see future and past existing in static manner)

Well, please read this, see what you think;
Definitions on space

-Anssi