Is Time Truly a Dimension or Something Else Entirely?

[Alfi]

My favorite definition of Dimension is as follows:


For the purposes of defining events in space-time, one of the variables included into the equation is time, which causes it to become a dimension by serving as a property that can be described by a real number and that defines the location of an element within an event in space-time in conjunction with other such properties that can be described by real numbers.

So from the preceding deductions, we can see that time is in fact a dimension,

I can see where time is defined as a dimension, for the purposes of defining events, but, is it really a cause and effect though?
What is the 'it' ?in, the inclusion of a variable into an equation that causes 'it' to become a dimension?

my reading skills may be impaired this morning. Happy birthday to me. :)

My favorite definition of Dimension is as follows:

or was that tongue in cheek? favorite.

I'm starting to think that science has a gap between the math of time and the perception of time in a conscience being. Same as Quantum has a hard 'time' expanding into the Macro.
The 'now', I perceive, can only be part of me opening the silly box and looking at the cat in real time.

 

[ChadRichens]

What is the 'it' ?in, the inclusion of a variable into an equation that causes 'it' to become a dimension?

For the purposes of defining events in space-time, one of the variables included into the equation is time, which causes it(time) to become a dimension by serving as a property that can be described by a real number and that defines the location of an element within an event in space-time in conjunction with other such properties that can be described by real numbers.

 

[Fredrik]

I'm starting to think that science has a gap between the math of time and the perception of time in a conscience being.

The time perceived is the same as the time measured.

There is always a "gap" between measurements and what corresponds to them in the appropriate mathematical model. A set of postulates (yes, postulates) that tell us how to bridge that gap is a theory of physics.

This is true about all measurable quantities, not just time, and the only connection with consciousness is that a conscious human can be thought of as a really bad clock.

 

[Dale]

This is true about all measurable quantities, not just time

I agree. That is why I mentioned mass earlier in this thread. It is not as easy to define as john 8 thinks, and once you understand mass it makes time easier to understand.

 

[atyy]

The time perceived is the same as the time measured.

There is always a "gap" between measurements and what corresponds to them in the appropriate mathematical model. A set of postulates (yes, postulates) that tell us how to bridge that gap is a theory of physics.

This is true about all measurable quantities, not just time, and the only connection with consciousness is that a conscious human can be thought of as a really bad clock.

Surely time measured by an ideal clock is more like a microscopic quantity, but time perceived is more like a macroscopic effective quantity? Does our perception even resolve time differences of less than 1 ns? I know barn owls can do ~1 micro-second.

 

[Fredrik]

That's why I said humans are really bad clocks.

 

[atyy]

That's why I said humans are really bad clocks.

Just like a proton is a really bad point charge?

 

[atyy]

That's why I said humans are really bad clocks.

How about cases where temporal order becomes ambiguous?

Try the first and second demos here. The physical temporal order of the high and low pitches is the same in both cases - but not the perceptual temporal order.
http://www.tc.umn.edu/~cmicheyl/demos.html

 

[atyy]

A physical mechanism will be made of electrons, protons and neutrons, physical mechanisms are not made of symbols.

Observational evidence means that it can be seen by our eyes.

Here's an interesting quote from Pauli that seems close to what you're saying. The symbol "gik" is usually cconsidered "spacetime". Although the statement is made in the context of GR, I am reminded that even in SR, it is different "events" (Ludvigsen gives the example of lightning striking a tree) which are primary, and spacetime is constructed by assigning different numbers to different events.

‘The generally covariant formulation of the physical laws acquires a physical content only through the principle of equivalence, in consequence of which gravitation is described solely by the gik and these latter are not given independently from matter, but are themselves determined by field equations. Only for this reason can the gik be described as physical quantities’ (as translated by Giulini, http://arxiv.org/abs/gr-qc/0603087)

But what is matter? Ehlers (in Stamatescu and Seiler, Approaches to Fundamental Physics) says: Here “matter” is used to denote all physical entities besides gαβ, i.e. everything which carries localizable energy and momentum. ... this specification always contains the metric. Matter models studied in some detail include perfect fluids, electromagnetic fields, collisionless particle systems idealized by kinetic theory and, to a lesser extent, elastic bodies. In these cases the system of partial differential equations ... the relevant matter law admits a (locally) well-posed initial value problem.

 

[chiro]

Hi everybody. I just recently joined this forum because I have been reading through the various sections and find it a lot more stimulating than other discussion forums.

I have been thinking about this subject myself and I may have some idea of what john 8 is trying to get at so here's my two cents.

To define time in both a mathematical and a physically measurable sense in a unified form we turn to geometry.

Now I'm not going to repeat the disccussion on general relativity and how time is defined through the change in events because that has already been well discussed. What I will do however is state that given a universal geometry G which contains the set of all events (usually in mathematics we denote it as omega) possible in accordance with global set of processes in the universal system, contains the starting point for which I define time.

Given this geometry G, a time-line is defined as the path taken from an initial event A to a final event B. Any mathematical expression will suffice as long as they unambiguously differentiate one unique time-line from another.

So in this respect time is defined as the distance traversed within the global space-time. This distance is measurable using the same notion of length that is used in normal euclidean geometry (in this case the metric is given by the square root of the sum of the squares).

If one event lies in the global geometry G at a point P and a possible future event lies at point F in the geometry then time is defined purely as the path taken to reach F from P. We can measure this using advanced geometric techniques.

In a multidimensional geometric theory we can use a few tools that we have developed as a result of mathematics. The notion of relative measure (or angular measure) is important as well as the notion of absolute measure (defined from the metric). With angular measure we are defined a form of measure of two points relative to some origin. By using the properties of given geometries and by measuring as accurately as possible the results that are the projection onto our currently perceptible 3-space, we can infer a particular geometry that corresponds to a set of physical processes P and thus through a metric define what we mean by "time".

Now if we build the relation between our universal geometric structure G and a local intuitive
structure (i.e. a local R^3 structure with orthogonal axis) then we can relate distance in
the global structure G to corresponding distance in the intuitive structure. This essentially
establishes a link between "intuitive" time and "universal time". The process I describe is
akin to linking a string theoretic definition of time in multidimensional universe or one of time
in an einsteinian universe to that of a Newtonian universe.

Once the link has been made between the various theories all you need to do is use a geometric physical measuring device (eg a ruler) and a known physical process (such as the behaviour of light) to measure time as time directly correlates to distance.

If I'm wrong I welcome any comments as I have only really just started to learn this kind of thing properly so if I'm wrong I'd welcome a seasoned expert to fix up where an amendment is needed.

I hope this helps.

Matthew

 

[nutgeb]

This topic is not capable of a definitive answer. One can somewhat arbitrarily but perfectly reasonably create a coordinate system with 3 spatial dimensions and 1 time dimension. It happens to be useful in simplifying the mathematical portrayal of certain concepts of relativity. But the fact that it is mathematically useful for that purpose imparts it no unique significance to "spacetime" as a physical concept or system. For example, one could imagine an alternative coordinate system in which the defined "dimensions" include 3 spatial dimensions, 1 time dimension, 3 color dimensions, 3 density dimensions, 3 temperature dimensions, 3 pressure dimensions, etc. But our ability to define that coordinate system and use it in calculations does not mean that this system of "space-time-color-density-temperature-pressure" is somehow more physically "real" or "unique" than the individual categories of dimensions from which it is built. In the same sense, the concept of "spacetime" is no more real or meaningful than treating the spatial dimensions separately from the time dimension.

 

[Dale]

In the same sense, the concept of "spacetime" is no more real or meaningful than treating the spatial dimensions separately from the time dimension.

I disagree. If it can predict the results of experiments better then it is more real and more meaningful.

Otherwise why would we bother doing experiments? If the results of scientific experiments don't tell us anything about the "meaningfulness" of our scientific theories then we should have just stayed with pre-scientific superstitions.

 

[nutgeb]

I'm just saying that although coordinate system based on a "bent" spacetime with a "straight" geodesic traveling through it is convenient and useful, that happenstance doesn't disprove that on the contrary the geodesic is "bent" and the spacetime is "straight." We can disagree in our opinions about this but there is no way currently to come to a definitive conclusion because we don't know the physical mechanism by which gravity works. Both possibilities should be treated as scientifically reasonable.

 

[atyy]

I'm just saying that although coordinate system based on a "bent" spacetime with a "straight" geodesic traveling through it is convenient and useful, that happenstance doesn't disprove that on the contrary the geodesic is "bent" and the spacetime is "straight." We can disagree in our opinions about this but there is no way currently to come to a definitive conclusion because we don't know the physical mechanism by which gravity works. Both possibilities should be treated as scientifically reasonable.

I think what you said is true even with in GR.

Thorne, Black Holes and Time Warps, 1994: Is spacetime really curved? Isn’t it conceivable that spacetime is actually flat, but clocks and rulers with which we measure it, and which we regard as perfect in the sense of Box 11.1, are actually rubbery? Might not even the most perfect of clocks slow down or speed up, and the most perfect of rulers shrink or expand ...? Wouldn’t such distortions of our clocks and rulers make a truly flat spacetime appear curved? Yes.

 

[Dale]

Both possibilities should be treated as scientifically reasonable.

In this post you are referring to different interpretations of the same theory, that is not what I was objecting to above. I (perhaps mistakenly) understood you above to be talking about Newtonian mechanics and special relativity, where there are experimental differences.

Personally, I have never been terribly interested in different interpretations of the same theory, all that matters are the predictions a theory makes and how well those predictions agree with experiments. The stories we tell ourselves are not terribly important. I think that a person should be aware of all of the different interpretations and use each of them when convenient. The "default" interpretation should always be the simplest one.

That said, in the math of all modern physical theories time is a dimension, and the theories agree very well with experiment. The interpretation you use does not change the math. Therefore, IMO, the topic is capable of a definitive answer in the affirmative.

 

[Sjorris]

I don't agree with you DaleSpam,
Interpretating a theory allows for completing, expanding or otherwise enhancing it, because you can venture qualitatively where you usually wouldn't go mathematically. QM in it's early days profited from this, and when Einstein tried to interpret Maxwell's equation he stumbled upon certain ideas which would later lead to SR (I'm referring to the thought-experiment said to be performed by Einstein in which he imagined himself being in the frame of reference of a photon, 'riding a beam of light' so to say).

Momentarily, no one has a clue how to distinct the two earlier named interpretations of how exactly spacetime is curved (spacetime itself or the geodesic), but when both interpretations excist, one might sooner or later come up with some way to verify which interpretation is the 'right' one, which one more closely resembles reality (or it may turn out the two interpretations are in fact effectively identical). Qualitative interpretation is, in my opinion, far more important than mathematical, as math is 'just' a tool (be it a very good one) and usually less understood by humans than thought in native language.

If you see a theory just as a complicated calculator to verify experiments with, then what is the point of having the theory?

 

[Fredrik]

If you see a theory just as a complicated calculator to verify experiments with, then what is the point of having the theory?

The point is that there's no better alternative. There's no way to directly obtain knowledge about the universe, so the best we can do is to come up with a theory that predicts the (probabilities of) results of experiments, and then perform the experiments. The only real facts in science are of the form "prediction A of theory B agrees with experiment C with accuracy D".

This doesn't mean that I disagree with your view that it might be useful to examine the interpretations more closely. It's certainly possible that one interpretation suggests a generalization of the theory in a more obvious way than the others.

 

[Dale]

Momentarily, no one has a clue how to distinct the two earlier named interpretations of how exactly spacetime is curved (spacetime itself or the geodesic), but when both interpretations excist, one might sooner or later come up with some way to verify which interpretation is the 'right' one, which one more closely resembles reality (or it may turn out the two interpretations are in fact effectively identical).

There is never any way to experimentally choose between two interpretations of the same theory, that is what distinguishes a new interpretation of an existing theory from a new theory.

Qualitative interpretation is, in my opinion, far more important than mathematical, as math is 'just' a tool (be it a very good one) and usually less understood by humans than thought in native language.

I guess here is our real disagreement. I find the math far more important than the qualitative "story" that we tell around the math. The reason is that both are "just tools" for understanding the universe, but the math is inherently logical, whereas the English is open to illogic, misunderstanding, and confusion. The vast majority of the posts on this forum are a direct result of something being mistakenly lost or added in the math-to-English translation. The universe doesn't "speak" English, but if it behaves logically then math is its language.

 

[Sjorris]

There is never any way to experimentally choose between two interpretations of the same theory, that is what distinguishes a new interpretation of an existing theory from a new theory.

Of course both interpretations are initially effectively the same, however as Frederik pointed out certain interpretations can more easily lead to generalizations and/or expansions, offering the possibility of predictions the other interpretation doesn't. Technically you are right though, the moment one interpretation yields different results it's in fact a different theory.

I guess here is our real disagreement. I find the math far more important than the qualitative "story" that we tell around the math. The reason is that both are "just tools" for understanding the universe, but the math is inherently logical, whereas the English is open to illogic, misunderstanding, and confusion. The vast majority of the posts on this forum are a direct result of something being mistakenly lost or added in the math-to-English translation. The universe doesn't "speak" English, but if it behaves logically then math is its language.

Ok, I might have been talking too much in absolutes. English is the language of english people, math and logic is the language of the universe. A mathematical formulation of a theory is far more rigid and not really open for confusion and/or misunderstanding, however when 'speculating' I tend to think in my own human language, and not in mathematics, especially in fields where I'm not experienced. Ideally, it would be superior when I could speculate and extrapolate theories purely in mathematics, however humans are limited in their understanding and use of mathematics, so that's why I prefer human language for such cases.
Obviously, for well explored fields of science a mathematical formulation is far better in every way.

I'm not finished with this post but I have to go, I'll post again later.

 

[Dale]

Ok, I might have been talking too much in absolutes.

No problem. I am very guilty of the same!

 

[yinfudan]

I hope I could try to answer boysherpa's question, although I just learned Special Relativity lately. Boysherpa has a very good point - what is the definition of time. It is important to understand what makes time before we discuss if time is a dimemsion.

I have a feeling that physics cannot measure the absolute value for anything; it can only measure the relative value against other things. For example, when you measure the length, you are measuring how many ticks on the ruler. So eventually, the length is defined as how far the light travels in a second, (say one meter is 1/300000 of the distance the light travels in a second). Probably the length can also be defined as how big is a fixed sized object, (say one meter is the length of n neutrons put side by side).

Because physics only measure the relative value, not the absolution one, we cannot even tell if the universe is changing if the measurement unit is changing as well. For example, can we tell if everything in the universe shrinks by half last night? The ruler will shrink by half as well; the atom size will shrink by half; the light will travel slower by half - but one light second is still 300000 times as long as a meter ruler. So probably we will notice nothing has ever changed.

Now let us go back to time, how is time defined? I think time is defined in a relative way as well. It is a measurement of how fast other things happen compared to a standard motion - for example, a clock tick. Similarly, if other things take only half time, but a clock runs double speed, we will not notice anything changed.

Traditionally, clock is made of mechanic devices, for example, a spring oscillator. A second is defined as how many times the oscillator runs a full cycle. Thus, clocks having higher frequency oscillators tend to have higher precision. In Special Relativity, Einstain defines time using light with a light clock. It counts how many time a light point bounces between two mirrors.

But the idea to define time with light is actually a concern to me: Since we define length with light and time (the distance light travels within a certain time), now we are defining the time with light and distance again (the amount of time the light travels between two mirrors). Is there any circular definition?

Or can I think this way: since the propagation of light creates both distance and takes time. Both length and time are defined with the help of light. So that it is inevitable that space and time are not separatable, and form so called spacetime, even though space and time are totally different things?

 

[atyy]

But the idea to define time with light is actually a concern to me: Since we define length with light and time (the distance light travels within a certain time), now we are defining the time with light and distance again (the amount of time the light travels between two mirrors). Is there any circular definition?

Or can I think this way: since the propagation of light creates both distance and takes time. Both length and time are defined with the help of light. So that it is inevitable that space and time are not separatable, and form so called spacetime, even though space and time are totally different things?

Yes, we cannot do that. Ohanian talks about this in his book "Einstein's Mistakes". Originally, we defined time in a way such that Newton's laws are true in a class of reference frames which we call "inertial". Then using those laws we measure the speed of light to be the same in all inertial frames. Then we know about Lorentz invariance. Nowadays we are so confident of Lorentz invariance and the constancy of the speed of light, that we define the speed of light to be constant without fear that we will cause objects moving at low velocities to disobey Newton's laws.

 

[Makep]

Time is the fourth dimension of existence and must be expressed by all moving systems. What would happen if relativity is not true and everything / systems in the universe stop moving. They would, probably, regress into oblivion. Matter would disappear, and space would disappear as well, then existence would also mean nothing.

 

[Sjorris]

That's highly unscientific and doesn't really mean anything... Time also is a fundamental quantity in non-moving systems, because nothing is in fact stationary, Only simplifications sometimes are called steady state, but obviously on the quantum level there is a lot going on which is dependant to time. Also, non-moving systems is kind of a absolute system, but we know only inertial can be absolute, systems moving at a constant speed might as well be standing still, or the other way around, there's no way to tell.
When relativity is not true, nothing really changes. Newtonian motion also desribes most of the observed behaviour very well, it was only after the discovery of relativity that effects caused by SR/GR were observed, not before (except that c is a constant). I don't really see any fundamental problems with GR/SR being not-existent.
For the universe to 'stop moving', well, we don't really know what happens then I guess, at the moment we don't even know if the (visible) universe is expanding or collapsing (as far as I'm concerned, there's a lot of conjecture in this topic and it seems to change from year to year), let alone predict what happens when everything is instantenously stopped everywhere in the universe. If you imply that everything will stay stationary, well, I don't think that's possible, where would all the energy come from to stop the huge amount of mass everywhere from accelerating?

 

[Austin0]

Well, I'll give it a shot. Distance isn't made of particles or waves. Is distance physical?

Time, like distance, isn't composed of particles or waves, but is used to describe intervals between physical events. This is why time is referred to as a dimension, because, like distance, two events can be separated by it. And this simple fact is the reason time (and distance) are useful concepts.

And any useful definition of time will be very similar to a useful definition of distance, in the sense that both are intervals between "physical things", not "physical things" themselves.

So, yes, time is a dimension instead of a substance.

Just a comment from the onlookers. I think your comments were very relevant and insightful.
But it appears to me that the main thrust of this debate is not about time as a concept like distance but about time as a concept like space. SO this is equivalent to trying to agree on the nature of space. I. e. Is it nothing [vacuum] ,aether, quantum foam ,etc, etc.
So some of you are talking about time [like distance] as a system of measuring intervals
[between events] and some of you are talking about time as an entity like space and considering its possible qualities or even existence outside of human abstraction.
Not much hope of a meeting of the minds here it would seem.

 

[Makep]

That's highly unscientific and doesn't really mean anything... Time also is a fundamental quantity in non-moving systems, because nothing is in fact stationary, Only simplifications sometimes are called steady state, but obviously on the quantum level there is a lot going on which is dependant to time. Also, non-moving systems is kind of a absolute system, but we know only inertial can be absolute, systems moving at a constant speed might as well be standing still, or the other way around, there's no way to tell.
When relativity is not true, nothing really changes. Newtonian motion also desribes most of the observed behaviour very well, it was only after the discovery of relativity that effects caused by SR/GR were observed, not before (except that c is a constant). I don't really see any fundamental problems with GR/SR being not-existent.
For the universe to 'stop moving', well, we don't really know what happens then I guess, at the moment we don't even know if the (visible) universe is expanding or collapsing (as far as I'm concerned, there's a lot of conjecture in this topic and it seems to change from year to year), let alone predict what happens when everything is instantenously stopped everywhere in the universe. If you imply that everything will stay stationary, well, I don't think that's possible, where would all the energy come from to stop the huge amount of mass everywhere from accelerating?

Am I confused or are you confusing in your opening statements with regard to movement. Consider your statement,

Time also is a fundamental quantity in non-moving systems, because nothing is in fact stationary, Only simplifications sometimes are called steady state, but obviously on the quantum level there is a lot going on which is dependant to time

.
There really can' be an existence without time. To generate time, a body must move - whether accelerating or at a constant velocity is not the issue.To exist without time is to be in the inertial frame of a bigger system - hence, still moving.

 

[Makep]

Just a comment from the onlookers. I think your comments were very relevant and insightful.
But it appears to me that the main thrust of this debate is not about time as a concept like distance but about time as a concept like space. SO this is equivalent to trying to agree on the nature of space. I. e. Is it nothing [vacuum] ,aether, quantum foam ,etc, etc.
So some of you are talking about time [like distance] as a system of measuring intervals
[between events] and some of you are talking about time as an entity like space and considering its possible qualities or even existence outside of human abstraction.
Not much hope of a meeting of the minds here it would seem.

Distance is space isn't it? Only that distance is the intervening space between two or more physical entities or events. So speaking about time as a concept like space is just like speaking about time as a concept like distance. In, fact both are same.

 

[john 8]

Hi everybody. I just recently joined this forum because I have been reading through the various sections and find it a lot more stimulating than other discussion forums.

I have been thinking about this subject myself and I may have some idea of what john 8 is trying to get at so here's my two cents.

To define time in both a mathematical and a physically measurable sense in a unified form we turn to geometry.

Now I'm not going to repeat the disccussion on general relativity and how time is defined through the change in events because that has already been well discussed. What I will do however is state that given a universal geometry G which contains the set of all events (usually in mathematics we denote it as omega) possible in accordance with global set of processes in the universal system, contains the starting point for which I define time.

Given this geometry G, a time-line is defined as the path taken from an initial event A to a final event B. Any mathematical expression will suffice as long as they unambiguously differentiate one unique time-line from another.

So in this respect time is defined as the distance traversed within the global space-time. This distance is measurable using the same notion of length that is used in normal euclidean geometry (in this case the metric is given by the square root of the sum of the squares).

If one event lies in the global geometry G at a point P and a possible future event lies at point F in the geometry then time is defined purely as the path taken to reach F from P. We can measure this using advanced geometric techniques.

In a multidimensional geometric theory we can use a few tools that we have developed as a result of mathematics. The notion of relative measure (or angular measure) is important as well as the notion of absolute measure (defined from the metric). With angular measure we are defined a form of measure of two points relative to some origin. By using the properties of given geometries and by measuring as accurately as possible the results that are the projection onto our currently perceptible 3-space, we can infer a particular geometry that corresponds to a set of physical processes P and thus through a metric define what we mean by "time".

Now if we build the relation between our universal geometric structure G and a local intuitive
structure (i.e. a local R^3 structure with orthogonal axis) then we can relate distance in
the global structure G to corresponding distance in the intuitive structure. This essentially
establishes a link between "intuitive" time and "universal time". The process I describe is
akin to linking a string theoretic definition of time in multidimensional universe or one of time
in an einsteinian universe to that of a Newtonian universe.

Once the link has been made between the various theories all you need to do is use a geometric physical measuring device (eg a ruler) and a known physical process (such as the behaviour of light) to measure time as time directly correlates to distance.

If I'm wrong I welcome any comments as I have only really just started to learn this kind of thing properly so if I'm wrong I'd welcome a seasoned expert to fix up where an amendment is needed.

I hope this helps.

Matthew

Hi Matthew.

You have stated much in your explanation of time. In all that you said you did not state if time was a physical thing or not. You said that you have recently join this form. Well I have to say that I have been asking the simple question of someone who thinks that time is a physical thing to just give evidence of this. A reference, a definition, something.

Some state that time is a real physical thing and never point to a real physical perception or reference. Look, either time is a physical thing or it isn't. If you say that time is a physical thing than give some supporting evidence, simple as that.

All physical things in this universe are made of energy. This energy comes in two forms,either a particle or a wave. If you know of a different form please say so. Otherwise, if you think time is a physical thing than just use scientific references or observations to back up your claim that time is a real physical thing.

There may be those on this form that know me and discount what I have to say about time not being a real physical thing, that is fine, but these same people who say that I am wrong, an idiot, that I am just "trolling" have never given any scientific evidence that I am wrong and they are right that time is a real physical thing.

This whole discussion can be put to rest if someone can provide any shread of evidence that time is a physical thing. Simple as that.

Just because someone believes or hopes that time is a real physical thing does not make it so. Where is the science that time is a physical thing.

Look, I have been saying that time is not a physical thing on this form for a while now. If anybody has given any evidence of the physical nature of time on this form or any form for that fact, than just post that link so that I can be shown that I am in error.

I will state for the record one more time, time is not a physical thing due to the lack of evidence that it is and the fact that those who state that time is a physical thing will not give any evidence to back up their assertion.

If you say time is a physical thing than just give some supporting data.

 

[Al68]

All physical things in this universe are made of energy. This energy comes in two forms,either a particle or a wave.

Time isn't a particle or wave, so no one would claim that time is a physical thing by your definition.

Some might want to use a different definition, like calling a dimension that separates events "physical", so that time and space are physical, but that's a matter of semantics only. And you know what they say about arguing about semantics.

 

[john 8]

This topic is not capable of a definitive answer. One can somewhat arbitrarily but perfectly reasonably create a coordinate system with 3 spatial dimensions and 1 time dimension. It happens to be useful in simplifying the mathematical portrayal of certain concepts of relativity. But the fact that it is mathematically useful for that purpose imparts it no unique significance to "spacetime" as a physical concept or system. For example, one could imagine an alternative coordinate system in which the defined "dimensions" include 3 spatial dimensions, 1 time dimension, 3 color dimensions, 3 density dimensions, 3 temperature dimensions, 3 pressure dimensions, etc. But our ability to define that coordinate system and use it in calculations does not mean that this system of "space-time-color-density-temperature-pressure" is somehow more physically "real" or "unique" than the individual categories of dimensions from which it is built. In the same sense, the concept of "spacetime" is no more real or meaningful than treating the spatial dimensions separately from the time dimension.

I disagree, this topic is capable of a definative answer. Things are either physical or they are imagined. If it is physical there will be perceptable evidence of it's existence. Simple as that. Is it real or imagined? Come on people, use science to figure this out.

Would you say that the topic of whether a rock is a real physical thing is a topic that has no definative answer? What about light? Is that topic up in the air, no definative answer?
What about air for that matter? Is that too just a topic that has no definative answer as to if it is a real physical thing? Come on! If something physically exists there is no debate, It exists due to it's actual physical nature.

Dimensions, space-time are either real physical thing or they are not. It is that simple. Where is the confusion? Here are your choices in solving this mystery for you.

Dimensions, space-time are real physical things (here is where you give scientific evidence).

If there is no evidence to support your assertion that dimensions or space-time are real physical things than either there is no evidence or it has not been found.

If you say that these things are real physical things but the evidence has not been found, than explain how you came to this conclusion.