Is Time Static Like Other Dimensions?

[ThomasT]

As exemplified wrt SR's twins (when they're reunited they both agree on the elapsed time of the traveling twin's journey wrt the Earth-Sun frame of reference even though their personal clocks record different times for the same journey), there's a hierarchy of reference frames. A room. A house. The Earth. The solar system. The Milky Way. And so on, to the universe. Of course, we have to use our imaginations a bit when it comes to what the spatial configurations of some of these things correlated with our NOWS might be -- because the universe is in a continual state of flux and the speed of light is finite -- but that doesn't imply that there isn't a universal configuration that corresponds to our local and personal NOWS. Remember the trees and forests, etc. Not knowing the current state of the forest doesn't imply that there isn't a current state of the forest.

We define the current or present spatial configuration of the observable universe based on observations and what we know about the behavior of light. Of course, some of the assumptions and inferences involved might be wrong, but, again, that doesn't mean that there isn't a current spatial configuration of the universe.

The well founded idea that the universe is an evolving spatial configuration, which we are a part of and not just traveling through, and wrt which (due to the fundamental dynamic of isotropic expansion) no instantaneous configuration can be repeated, is clearly at odds with eternalism.

I don't think we should interpret the mathematical constructs of GR (and QM as well) literally, because there's no definitive reason to think of them as qualitative descriptions of deep physical reality, and there are reasons to think that they're not very accurate as qualitative descriptions of deep physical reality. They're a means of calculating quantifiable instrumental behavior, and they should be taken as descriptions only wrt the instrumental level.

Apparently we do select some slicings as present (and probable future) configurations rather than others, else GR wouldn't be of much use.

I agree that, observationally, there's no absolute present. But, as noted above, this doesn't mean that there's no set of spatial configurations in higher order frames of reference corresponding to the set of spatial configurations in my personal experience of the world that I refer to as the present. I might not know what these are (eg., I don't know if any trees fell in the forest last night), but that doesn't mean that there isn't a present configuration of the forest, or any other frame of reference, as well as a present configuration of the room I'm in.

If TIME is an index, an ordered record, of discretized, unique, and transitory spatial configurations of an expanding evolving universe, then none of the spatial configurations that collectively define TIME exist in any form other than as historical records of one sort or another.

So, what do the words NOW and the PRESENT mean? Obviously, they have some physical meaning. We all use these words, and their use elicits predictable responses.

Eternity, on the other hand, is a rather more sticky wicket.

 

[xantox]

We define the current or present spatial configuration of the observable universe based on observations and what we know about the behavior of light. Of course, some of the assumptions and inferences involved might be wrong, but, again, that doesn't mean that there isn't a current spatial configuration of the universe. [..]
I don't think we should interpret the mathematical constructs of GR (and QM as well) literally, because there's no definitive reason to think of them as qualitative descriptions of deep physical reality, and there are reasons to think that they're not very accurate as qualitative descriptions of deep physical reality.

In GR there is fundamentally no time and no space, but just pure dynamics. It's true that this could be wrong, but GR (or even Newtonian theory) offers a more fundamental and correct view on nature than common sense does.

So, if our positions are not going to converge further we shall acknowledge that one difference on our views is that while we both agree that both common sense and GR or QM have no last word to say on ontological issues such as the presentism vs eternalism debate, I consider that GR or QM have more, not less, to say than common sense, and that they can't be sidestepped. While their concepts may seem more abstract, they are in fact less abstract, as apart from modeling known phenomena they can predict new subtler ones which are confirmed by observation, and that modeling, prediction and observation feedback is exactly the same process that we (or anything having knowledge, say birds) use, to validate their own common sense models of reality too. So while the mathematical concepts of GR and QM are certainly not exact, and should not be taken too literally, the common sense models should be taken even less literally.

I agree that, observationally, there's no absolute present. But, as noted above, this doesn't mean that there's no set of spatial configurations in higher order frames of reference corresponding to the set of spatial configurations in my personal experience of the world that I refer to as the present.

If we use higher order representations, then different names have to be used too for them. Space and time is something quite precisely defined and a higher order present is not what we should call a present. And it would not lead to presentism, but to higher order presentism – already a first step away from the vanilla dichotomy we started with. In hamiltonian general relativity this higher order present could be some point in superspace, though there is still no mean to select a preferred foliation within the theory.

Here is where the best theories leave us today. A step forward, though we already enter speculation, is to consider causality as a more fundamental basis than spacetime. Or suppose some underlining process similar to a cellular automata. However quantum mechanics is at odds with such a view and causality itself. However a further step forward is possible by considering causal sets or quantum computation graphs. And another step forward is possible by considering superpositions of them. And these tortuous paths continue. So while no solution and no final word is offered by following them, it seems to me that this help at least to understand the non-trivial nature of these questions and the incredible deepness of nature.

 

[ThomasT]

In GR there is fundamentally no time and no space, but just pure dynamics. It's true that this could be wrong, but GR (or even Newtonian theory) offers a more fundamental and correct view on nature than common sense does.

So, if our positions are not going to converge further we shall acknowledge that one difference on our views is that while we both agree that both common sense and GR or QM have no last word to say on ontological issues such as the presentism vs eternalism debate, I consider that GR or QM have more, not less, to say than common sense, and that they can't be sidestepped.

While their concepts may seem more abstract, they are in fact less abstract, as apart from modeling known phenomena they can predict new subtler ones which are confirmed by observation, and that modeling, prediction and observation feedback is exactly the same process that we (or anything having knowledge, say birds) use, to validate their own common sense models of reality too. So while the mathematical concepts of GR and QM are certainly not exact, and should not be taken too literally, the common sense models should be taken even less literally.

Well put, and I agree. However, the idea that the universe is a spatial configuration in continual transition isn't a common sense idea -- and the eternalism suggested by a literal translation of GR constructs is at odds with this. Taking the observations and what I consider to be the most reasonable interpretations of the formal constructs of GR, QM, and Newtonian physics into account, I think that the observational and inferential evidence supports the transitory view, and hence, some version of presentism.

If we use higher order representations, then different names have to be used too for them. Space and time is something quite precisely defined and a higher order present is not what we should call a present. And it would not lead to presentism, but to higher order presentism – already a first step away from the vanilla dichotomy we started with. In hamiltonian general relativity this higher order present could be some point in superspace, though there is still no mean to select a preferred foliation within the theory.

I meant higher order in terms of scale, not dimension. Speaking of the present state of the 3D universe is conceptually the same as speaking of the present state of the room I'm in, or the present state of the forest in the park that's about a mile from my house.

Here is where the best theories leave us today. A step forward, though we already enter speculation, is to consider causality as a more fundamental basis than spacetime. Or suppose some underlining process similar to a cellular automata.

Or perhaps a fundamental wave mechanical dynamic(s).

However quantum mechanics is at odds with such a view and causality itself.

I don't think that QM is at odds with a wave mechanical view of things. Isn't quantization a function of harmonic ordering?

QM isn't at odds with causation, it just isn't a causal (ie., realistic) theory, but rather a correlational, probabilistic one.

However a further step forward is possible by considering causal sets or quantum computation graphs. And another step forward is possible by considering superpositions of them. And these tortuous paths continue.

Yes, tortuous, and, imho, essentially incorrect if what is being sought is a unifying conceptual basis for all physical theories.

So while no solution and no final word is offered by following them, it seems to me that this helps at least to understand the non-trivial nature of these questions and the incredible deepness of nature.

I agree that Nature is deeper than common sense -- that there's more to reality than meets the eye, so to speak. But, at the same time, we and what we sense are part of Nature -- and I see no reason to assume that the dynamics of processes in media that are invisible to us are essentially different than the dynamics which govern the world of our senses.

Quantum experimental phenomena seem to me to suggest that deep reality is as transitory as our (common) sensory reality seems to be -- at least, they don't provide any evidence that it isn't.

 

[ThomasT]

xantox, since writing the above I've learned a few more things and, I agree, the possible paths (steps) toward a deeper understanding of Nature that you mention (including info theory) will all come into play and have something to contribute.

This discussion has been very helpful for me, even if I don't fully understand all the issues, and ways of talking about them, that are involved (especially the ways that professional philosopher deal with it).