As far as I know, for something to be said to actually exist in a scientific way, it has to consist out of matter or energy. What about time then? Is it simply just a measurement for us? Kind of like how coordinates doesn't exist, but it's a way of helping us out with a lot of things. But time can be bent. So if what is real only consists out of matter or energy, how does time fit in? Also, dark matter, is that considered a type of matter?

I don't think that time is a fundamental feature of reality.

Paul Almond wrote:I don't think that time is a fundamental feature of reality.

As soon as you say that time emerges from or is produced by something more fundamental, you're contradicting yourself, because emergences and productions presuppose time.

"Everyone in string theory is convinced…that spacetime is doomed. But we don’t know what it’s replaced by. We have an enormous amount of evidence that space is doomed. We even have examples, mathematically well-defined examples, where space is an emergent concept…. But in my opinion the tough problem that has not yet been faced up to at all is, “How do we imagine a dynamical theory of physics in which time is emergent?” …All the examples we have do not have an emergent time. They have emergent space but not time. It is very hard for me to imagine a formulation of physics without time as a primary concept because physics is typically thought of as predicting the future given the past. We have unitary time evolution. How could we have a theory of physics where we start with something in which time is never mentioned?"

(David Gross, quoted in: http://www.iep.utm.edu/time/#SH3f)

If you want some entertainment on the nature of time, have a rummage through these essays

variable quality, but some good ones, like Fotini Markopolou's for example

Teuton wrote:

Paul Almond wrote:I don't think that time is a fundamental feature of reality.

As soon as you say that time emerges from or is produced by something more fundamental, you're contradicting yourself, because emergences and productions presuppose time.

I find that simplistic and disagree with it. I didn't say that time is "produced" by something that we could think of as a "process" occurring in "time". if I thought that - yes, I would be contradicting myself. I don't require that all explanations include a temporal aspect. I don't think that the explanation of a thing must be in terms of something happening. Rather, the explanation of a thing can simply be in terms of some feature of a more general structure of relations of which it is a part - and temporal and spatial explanations are a subset of all the possible explanations of this kind that can be conceived.

[i]But in my opinion the tough problem that has not yet been faced up to at all is, “How do we imagine a dynamical theory of physics in which time is emergent?"

and I say, "We don't!" I am not saying that there is any "dynamical theory of physics" down there, "underneath" time. I view things like "dynamical theories of physics" as special case explanations - admittedly, ones that work extraordinarily well in our local reality - the part to which we have access. To me, concepts such as "space", "time", "motion", "event", "happen", "cause" and so on can all be viewed as things that do not have to be fundamental.

As long as I can measure it, it exists. We have for instance geologic time.

personally I really like carlo rovelli because I have had thoughts very similar to his papers including his relational QM. But its very strange, why should our predictions match the experiments with the help of time in our equations. And how does it deal with causality?. The way I think is that causality now perhaps deserves greater attention than before, for all ideas of time are built on this foundation. The nature of causality shall perhaps lead us towards understanding the nature of 'time'.

cavarka9 wrote:personally I really like carlo rovelli because I have had thoughts very similar to his papers including his relational QM. But its very strange, why should our predictions match the experiments with the help of time in our equations. And how does it deal with causality?. The way I think is that causality now perhaps deserves greater attention than before, for all ideas of time are built on this foundation. The nature of causality shall perhaps lead us towards understanding the nature of 'time'.

Well, yeah, the causal structure of spacetime is defined by the null rays, so what you want to look at is the space of null rays....

but what about quantum entanglement and epr paradox.

Everything we can give a name to exists, and quite a lot of things we can't name exist as well. It's just a question of where they exist - in what domain of reality? Racism exists, Islamophobia exists, so do pleasure, pain and emotion. Even God exists. Some things exist in our imagination and some things exist in our external reality. Of course, our internal reality must create a model of our external reality in order to perceive it. To that extent, everything exists in our internal reality. You might say that's the point of the question - that when we say something 'exists', we mean more than it just being a figment of our imagination or a mere construct of our internal reality. But how do we tell the difference? Possibly the only way is to compare our perception of external reality with that of other people; the more people that agree, the more plausible it is that something is real in our external reality.

But that only works if we suspend our knowledge that other people we know are in our heads also as a model of the people we know in our external reality. We might like to reassure ourselves that although we can often predict what people will say, they nevertheless have freedom and can very easily step outside their patterns and give us a very unpredictable and surprising response to a question.

In a time when everybody in my country was Christian (I don't know if such a time ever existed) the general consensus would have been that God exists in the real external world and anybody who disagreed would have been thought a nutter. But is time a bit like God in that respect? We have moulded our whole sense of social reality around the concept of time. We read clocks. We write down dates. We perform scientific calculations based on the regularity of time. Our language has a past and future tense. Everybody uses time, everybody believes in it. It is, as has been said, the only thing that stops everything happening simultaneously.

But maybe we have misconstrued time. Maybe everything really is happening simultaneously. In that case, we should abolish the past and future tenses, and get rid of clocks and dates. It would be a great intellectual experiment to construct a new version of reality based on the non-existence of time. To be honest, I don't see a compelling reason not to try.

Paul Almond wrote:
I don't require that all explanations include a temporal aspect. I don't think that the explanation of a thing must be in terms of something happening. Rather, the explanation of a thing can simply be in terms of some feature of a more general structure of relations of which it is a part - and temporal and spatial explanations are a subset of all the possible explanations of this kind that can be conceived.

Not all possible explanations are causal explanations, but the only space- and timeless structures there are are abstract mathematical structures, which are by definition static, i.e. motion- and changeless. But the physical world is concrete and dynamic.

Paul Almond wrote:
I am not saying that there is any "dynamical theory of physics" down there, "underneath" time. I view things like "dynamical theories of physics" as special case explanations - admittedly, ones that work extraordinarily well in our local reality - the part to which we have access. To me, concepts such as "space", "time", "motion", "event", "happen", "cause" and so on can all be viewed as things that do not have to be fundamental.

What (meta)physical concepts are conceivably more fundamental?

cavarka9 wrote:personally I really like carlo rovelli because I have had thoughts very similar to his papers including his relational QM.

"Objects interact with other objects, and this is reality. Reality is the net of these interactions. We do not need an external entity to hold this net. We do not need Space, to hold the universe."
(p. 32)

"GR [= general relativity] inherits from SR [= special relativity] the melting of space and time into spacetime. Therefore the relational nature of space revealed by GR extends to time as well. It follows that in GR there is no background spacetime and therefore in particular no time along which things happen. GR teaches us that we must abandon the idea that the flow of time is an ultimate aspect of reality. The best description we can give
of the world is not in terms of time evolution. The dynamics of GR itself cannot be cleanly described in terms of evolution in time."
(p. 33)

"Some people find the absence of time difficult to accept. I think that this is just a sort of nostalgia for the old Newtonian notion of an absolute 'Time' along which everything flows, a notion already shown by SR to be inappropriate for understanding the real world."
(p. 35)

(Rovelli, Carlo. "The Disappearance of Space and Time." In The Ontology of Spacetime, edited by Dennis Dieks, 25-36. Vol. 1 of Philosophy and Foundations of Physics, edited by Dennis Dieks and Miklos Redei. Amsterdam: Elsevier, 2006.)

So the title should read more precisely "The Disappearance of Space and Time as Absolute and Substantial Background Containers". According to Rovelli, spacetime is ontologically reducible to spatial and temporal relations between physical objects which don't exist in spacetime and aren't occupants thereof.
Rovelli seems to combine spacetime relationalism with the tenseless B-theory of time, according to which there is no "flow of time".
Nevertheless, the concepts of spatiality and temporality still play an indispensable role. For instance, physical objects may not exist in space but they are still spatial in the sense of having a certain (nonzero) volume. (Zero-dimensional point-particles are nothing but mathematically idealized non-zero-dimensional physical objects.)

We never measure time. All we ever measure is change. Time seems to emerge from the concept of change and not be something fundemental.

I BELEIVE THIS THREAD SHOULD BE MOVED TO THE PHILOSOPHY SUB-SECTION.

zaybu wrote:I BELEIVE THIS THREAD SHOULD BE MOVED TO THE PHILOSOPHY SUB-SECTION.

Yes, but when?

zaybu wrote:I BELEIVE THIS THREAD SHOULD BE MOVED TO THE PHILOSOPHY SUB-SECTION.

Why?

I don't think we can say that time does not exist as a feature of our existence as it is obviously at the core of of our experience. It is the mechanism by which we are capable of experience. I think the proper question is: What is the true nature of time. At the moment I think we can only provide philisophical answers to this question.