What is "spacetime" really?

[Pyrotex]

...And, Michael,

you are continuing to be as unclear as you were and I have no idea as to what you are thinking other than that “you are right”. Erasmus00 is quite correct; you are not working out the logical consequences of your position. That is, in fact, the major flaw in most all “belief systems”. Squirrel thought is a very powerful mechanism for making life and death decisions but you are just plain fooling yourself to think it is without flaw...

I'm with Doctordick and AnssiH.

Michael and others have not been very clear at all.

In fact, my posts weren't very clear either.

So, there!

[Michael Mooney]

Watcher:

think it this way michael.

if you take a snapshot of two point particles in space, there is a probability that you would capture 1. both in a picture 2. only either one in the picture 3. none. if you take lot of series of snapshots, then and only then you can know what is happening. what do you make of it.

Think of it this way, Watcher... (Forget the snapshot for the moment, as it was merely the elimination of the time factor as in "spacetime" for the purpose of illustration.):

Whether we are talking of virtual points or actual objects in space, the distance between them (which is a straight line) remains the same until one or the other or both move relative to the other or each other. This is just obvious. The whole bit about the "spacetime interval between" them assumes the "reality" of spacetime as something that expands, contracts, dilates, curves, has shape, etc., which ontology this thread is challenging, ergo not to be assumed as a given fro0m the git-go. See?

 

This should also answer your challenge, Erasmus. This is "the philosophy of science", specifically a thread challenging the ontological reality of "spacetime," not the empirical discussion of experiments and their results you keep throwing at me. Seems that you are totally ignoring Doctordick's and AnnsiH's comments (and mine) on this point of your ontological assumptions about spacetime. Your stuck on a 'show me your evidence' challenge, whereas the "burden of proof" for an assumed medium, spacetime, as above is on the theorists who invented it.

Please notice my repeated references to "the matrix field" as a conceptual overlay and math as its analytical tool as contrasted with the "matter field" or the actual "territory"... the manifest cosmos which the matrix field merely *re-presents .* Now, this matrix (relativity theory) and its math are mighty fine tools for various purposes, including describing the effects of gravity way better than Newtonian physics, as I've said frequently, and correcting for lightspeed time delay between various relative perspectives, to yield the *actual distance* between things at any given time, simultaneous to both or all "things" in question.

 

I hope this is clear. It is as clear as I can make it.

Michael

[Michael Mooney]

Doctordick:

you are continuing to be as unclear as you were and I have no idea as to what you are thinking other than that “you are right”. Erasmus00 is quite correct; you are not working out the logical consequences of your position. That is, in fact, the major flaw in most all “belief systems”. Squirrel thought is a very powerful mechanism for making life and death decisions but you are just plain fooling yourself to think it is without flaw.

 

What exactly, say in my post #422 above is unclear. It's easy to take potshots at me without specifics and quite another to engage in a "mature" dialogue focusing on specific points of disagreement or asking for clarification on what is "unclear."

This is the same point I made to you in your original criticism of me as not understanding relativity. I had given several points of agreement with both SR and GR and hammered away as always on the ontological assumptions of the "spacetime" aspect of relativity. I asked you then to be specific on what exactly you were criticizing, but you refused. (I am sorry I "gave you the finger.")

 

So do you want to just assume a superior understanding or talk about our differences?

Michael

[Michael Mooney]

To the forum,

Just to re-focus on the basic question this thread poses:

Ontologically speaking, what is it exactly that "science" claims to have such properties as curvature (as distinguished from the surface of various Euclidean geometric shapes) expand/contract-ability (as distinguished from cosmic "stuff" expanding outward from the Bang into empty space,) and dilation (as per the "slowing down of time" as distinguished from the slowing down of clocks.)

 

And, While I am "back to basics", what is the reality of non-Euclidean space in "the real world. This question goes back to my repeated challenge, never answered, starting with "the shortest distance between two points being a straight line... See my "line on paper" example awhile back... then bent into an arch with a needle through the points... the new "shortest distance.

Then go to how parallel lines intersect in non-Euclidean geometry... as visualized on a curved surface, ontologically assumed to be "space itself" rather than the surface of an actual sphere, "saddle" parabola, torus, etc .

 

Then there was the recent offering in this thread of the "triangle" drawn on a spherical surface, like Earth, having more than 180 degrees, therefore proving the "reality" of "curved space." See my reply. I'll find it if requested.

 

Then there was the geometry lesson as to what a line, plane, and geometric volume are... a cube in this case. The argumnet was then that if you grow the cube bigger, it illustrates another "spacial dimension." (It in fact merely enlarges the dimensions of the cube. Neat computer graphics tho!:smilingsun:

 

I know that moderators here believe that the "advance beyond Euclidean space" is a given, long ago established and verified by the experimental and measured results of testing relativity theory.

So, humor me. There seems to me to be a huge ontological assumption, now totally taken for granted, that non- Euclidean space describes *reality* better than Euclidean. Given the examples above, point by point... clarify the *reality* of the leap to non-Euclidean.

 

And if you posit "higher" or "additional dimensions," please know what it is in the real world that you are talking about... not just matrix models and its math!

 

Thanks.

Michael

[maddog]

Ontologically speaking, what is it exactly that "science" claims to have such properties as curvature (as distinguished from the surface of various Euclidean geometric shapes) expand/contract-ability (as distinguished from cosmic "stuff" expanding outward from the Bang into empty space,) and dilation (as per the "slowing down of time" as distinguished from the slowing down of clocks.)

Your first post was asking "what is spacetime" ? I can address that better first.

 

As has already been said elsewhere on this veerryy long thread:

Spacetime is a construct of putting 3 coordinates of "space" and one of "time" together.

This is done with a Minkowski metric. As you well know distance is measured in say

meters or feet and time in seconds, etc. Since these are not the same, we can make

them similar by multiplying time t by ic (where c = speed of light and i = sqrt(-1)).

This is how the metric distance function ds^2 = x^2 + y^2 + z^2 - (ict)^2.

I'm not ontologically sure what one can say of curvature with any realistic meaning.

However, in the context of Differential Geometry (that which includes all forms of

Non-Euclidian and Euclidian Geometry) - Curvature is the bendedness of your current

Coordinate system. You cannot deny this being done in mathematics as it is what Differential Geometry is all about. I suppose you could say that such is meaningless to

reality. Most physicists would disagree. Yet without the fabric of mathematics you

can't really discuss much better that moving the deck chairs on the Titanic -- which

appears what I have read from this thread so far.

And, While I am "back to basics", what is the reality of non-Euclidean space in "the real world. This question goes back to my repeated challenge, never answered, starting with "the shortest distance between two points being a straight line... See my "line on paper" example awhile back... then bent into an arch with a needle through the points... the new "shortest distance.

Then go to how parallel lines intersect in non-Euclidean geometry... as visualized on a curved surface, ontologically assumed to be "space itself" rather than the surface of an actual sphere, "saddle" parabola, torus, etc .

All part of a Non-Euclidean Geometry where the coordinate system itself is deformed.

Then there was the recent offering in this thread of the "triangle" drawn on a spherical surface, like Earth, having more than 180 degrees, therefore proving the "reality" of "curved space." See my reply. I'll find it if requested.

It turns out this is true a triangle mapped onto a sphere will subtend all angles to more than 180 degrees.

Then there was the geometry lesson as to what a line, plane, and geometric volume are... a cube in this case. The argumnet was then that if you grow the cube bigger, it illustrates another "spacial dimension." (It in fact merely enlarges the dimensions of the cube. Neat computer graphics tho!:)

In which type of Non-Euclidean geometry ? In a hyperbolic space the corner of the cube closest to you would appear larger than farther away.

I know that moderators here believe that the "advance beyond Euclidean space" is a given, long ago established and verified by the experimental and measured results of testing relativity theory.

Theory worked out in 19th Century by Lobachevsky and Reimann.

So, humor me. There seems to me to be a huge ontological assumption, now totally taken for granted, that non- Euclidean space describes *reality* better than Euclidean. Given the examples above, point by point... clarify the *reality* of the leap to non-Euclidean.

Fact can be stranger than fiction.

1. Eddington's measure of the bending of light - Eclipse 1917.

2. 45 sec or arc is procession of perihelion of Mercury by Einstein.

3. Gravitational Lensing predicted by Einstein and observed for about 200 galaxies so far.

4. Error calculations used to calibrate GPS to such high accuracy.

I could go on.

 

And if you posit "higher" or "additional dimensions," please know what it is in the real world that you are talking about... not just matrix models and its math!

In higher dimensions matrices are about the Only way to handle all the coordinate indices.

 

That answers your questions.

 

Now as to the fallacies you are playing with.

 

1. Spacetime is not Just Space and Time put together like I described above.

That is a simple approximation.

Spacetime puts real-world constrainsts on causality already deeply discussed by Modest above.

 

I will have to cut it off there as my wife will be demanding me home any moment.

 

maddog

[Michael Mooney]

maddog:

Spacetime is a construct of putting 3 coordinates of "space" and one of

"tim

e" together.

Maybe you are not clear on what *ontological* inquiry into the *reality* of "spacetime* in the "real world" means. Yes. I agree that it is just a "construct" in service to relativity theory. I've affirmed 3-D space and event duration (time) maybe 100 times in this thread. So, unaware of this you repeat the obvious.

This is done with a Minkowski metric. As you well know distance is measured in say

meters or feet and time in seconds, etc. Since these are not the same, we can make

them similar by multiplying time t by

... by the following math... Hey... units of measure are not the issue here. We all know the conversion factors for these units, whether light seconds/minutes/years or kilometers, miles, earth diameters, astronomical units or whatever. ic (where c = speed of light and i = sqrt(-1)).

This is how the metric distance function ds^2 = x^2 + y^2 + z^2 - (ict)^2.

I'm not ontologically sure what one can say of curvature with any realistic meaning.

Well... that is the challenge of this thread... the ontology of "curved space", etc., etc. I have asked for commentary on the ontological assumptions behind "spacetime" and you are just giving me more of what the moderators here keep hammering on: That the "metric field" and its math are internally consistent, and a great tool for predicting "relativistic" phenomena. This does not address the ontology of spacetime. You are back to something like 'I dunno about ontology but...'here again is the epistemology, assuming that spacetime need not be question... being just a "construct" after all. You totally miss the point of my inquiry/challenge inb this thread.

However, in the context of Differential Geometry (that which includes all forms of

Non-Euclidian and Euclidian Geometry) - Curvature is the bendedness of your current

Coordinate system.

So the "matrix" is a "curved concept of space." Ontologically, what, in the real world, is "curved?"[/QUOTE]

 

You cannot deny this being done in mathematics as it is what Differential Geometry is all about. I suppose you could say that such is meaningless to

reality. Yes you could... until the ontological referents in the real world are made explicit. Most physicists would disagree. Yet without the fabric of mathematics you

can't really discuss much better that moving the deck chairs on the Titanic -- which

appears what I have read from this thread so far.

"The fabric of mathematics" must connect with the concepts it purports to elucidate, and these concepts must then be explained as accurate descriptions of the "real world. "Most scientists"... all, I think so far contributing to this thread, neglect the last two steps... and just assume the matrix and its math have counterparts in the "matter/energy matrix" of "the real world... ignoring the ontological question ("spacetime??" completely![/quote]

 

All part of a Non-Euclidean Geometry where the coordinate system itself is deformed.

So the "matrix" is "deformed." How does this describe real "space" ("real" in the sense of that emptiness/volume in which actual things exist?)

 

Yet without the fabric of mathematics you

can't really discuss much better that moving the deck chairs on the Titanic -- which

appears what I have read from this thread so far.

 

I think you have math as primary reality and that which it attempts to describe as secondary. Par for the course for most mathematicians. You have screened your reading of this thread through exactly this error/bias. If "spacetime" is just a metaphore/concept then what is it that "curves" etc. in the real world the concept attempts to describe?

 

It turns out this is true a triangle mapped onto a sphere will subtend all angles to more than 180 degrees.

 

I granted that in the original debate. Then I asked how such a "triangle" on a curved slice of earth's surface (apex at pole and base on a segment of the equator) is evidence for "curved space" as an entity other than surfaces of geometric shapes. No reply. I assumed concession of the point. Are you "caught up" yet?

 

In which type of Non-Euclidean geometry ? In a hyperbolic space the corner of the cube closest to you would appear larger than farther away.

 

Please go to the "geometry lesson" link which Watcher provided above. It is exactly what I said... an enlargement of a cube posing as an illustration of a fourth spacial dimension. This is the kind of argument I'm getting here for the validity of "non-Euclidean space."

 

In which type of Non-Euclidean geometry ? In a hyperbolic space the corner of the cube closest to you would appear larger than farther away.

 

Ontologically speaking, one must first establish that space is *something* that can curve, rather than being emptiness (in between "things.) Then one is philosophically "allowed" to theorize what *shape* this "fabric" or whatever might be. Do you get this point or not?

 

Theory worked out in 19th Century by Lobachevsky and Reimann.

 

So it is a given that Euclidean is proven wrong and non-Euclidean the correct description of reality? This totally avoids the ontological questions I am here asking. So Einstein and Minkowski invented "sapcetime," and who would question such genius.?

See my comments on the "hole argument" above. I have lots of notes on the link that one came from if you want to go into detail about the ontology of the conceptual/ model/map matrix as contrasted with the "matter/energy matrix" of the real world.

But the ontological difference will elude you, if I read your bias here correctly, as above.

 

Fact can be stranger than fiction.

1. Eddington's measure of the bending of light - Eclipse 1917.

2. 45 sec or arc is procession of perihelion of Mercury by Einstein.

3. Gravitational Lensing predicted by Einstein and observed for about 200 galaxies so far.

4. Error calculations used to calibrate GPS to such high accuracy.

I could go on.

 

You could, but I have already agreed in principle that all of the above are well established aspects of relativity theory, and you clearly are not aware of what I accept, as for instance the examples above, and what I reject, as for the several hundredth time, the reification of "spaceitme" as a required axiom of relativity theory. Whew!

 

In higher dimensions matrices are about the Only way to handle all the coordinate indices.

What "higher dimensions?"... really... as per my challenge to non-Euclidean space as a basis of the medium "spacetime." I asked that respondents know what such "dimensios" actually are in the real world and give clear evidence/arguments for their actual existence. Just saying " higher dimensions matrices" does not in fact establish their ontological vaslidity, but in fact simply *assumes* such validity without addressing the ontology.

 

That answers your questions.

You might have asked if this answers my questions rather than assuming what you can not know about me. No it does not. I have exposed that you are a novice in ontology, totally clueless about what this thread is actually challenging... yet you assume (you *assume* volumes without ontological examination!) that you have set me straight.

 

Now as to the fallacies you are playing with.

No judgmental bias there! Of course your "take" is the last word on reality here, tho you are unfamiliar with the disciplined study of "What is real... What actually exists?)

 

1. Spacetime is not Just Space and Time put together like I described above.

That is a simple approximation.

Spacetime puts real-world constrainsts on causality already deeply discussed by Modest above.

How does a "construct" ("spacetime") "put real-world constraints" on causality. You so obviously have the cart before the horse here, that I don't think any ontological argument, as above can make it through your screen of pre-conceptions.

 

I will have to cut it off there as my wife will be demanding me home any moment.

Later,

Michael

[Michael Mooney]

Originally Posted by Michael Mooney

Sounds like logic, but what is the logical necessity? There is none. It is nonsense. All events are happening right now simultaneously, regardless of how far apart they are. An event that happened last year is not happening now. Uh, yeah, ok...

 

Erasmus:

If the speed of light is constant for all observers, then this is deductively not possible. In special relativity its not just that events are observed in a different order, its that the events must have happened in a different order

.

 

With what part of the above are you disagreeing? I agree that the speed of light is constant for all observers. So "this" what is deductively not possible?

 

I keep hammering on the universal, omnipresent NOW... that the present is present universally, everywhere.

 

So, for instance the actual distance between objects does not depend on relative perspectives, their velocities, or who (figuratively) sees what and when. The latter will obviously be different with lightspeed time delay in conveying images.

 

So what one relative perspective can "see" relative to another is well and accurately handled by relativity. This does not even address the ontology of universal simultenaity... that the present is present everywhere... right now.

 

Modests "logic" had no logical necessity between his "If" and his "then." Hope you know what "logical necessity" means. Beyond that, if the assumption is not true the conclusion will not be true either just because the assertion is stated in formal logical sequence.

Edit:

Here is his quote again, to which I responded in the first quote above:

If there exists an inertial frame of reference where spatially separated events are simultaneous then there must exist another equally valid inertial frame of reference where the events are not simultaneous

 

Modest has "inertial frame of reference" as the only and absolute reality. He can not comprehend universal simultenaity... that Now is omnipresent everywhere. It just doesn't register for him as reality now everywhere transcending his central importance of time, specifically the time it takes information to travel through space... which is obvious. His "if" above makes simultenaity a special case, whereas it is the universal NOW. Then he affirms the obvious: that things that happened in the past or will happen in the future are not in fact happing now... not simultaneous.

Yup, everything happening now is happening simultaneously ... regardless of "spacial separation." And things that happened at different times were not simultaneous or are not simultaneous with what's happening now... everywhere/anywhere.

This is just so obvious....

 

Michael

[watcher]

Think of it this way, Watcher... (Forget the snapshot for the moment, as it was merely the elimination of the time factor as in "spacetime" for the purpose of illustration.):

Whether we are talking of virtual points or actual objects in space, the distance between them (which is a straight line) remains the same until one or the other or both move relative to the other or each other.

 

yes, i think we have agreed on that already.

like in my snapshot illustration, when you chanced upon a picture that both particles appeared, you can make measurement. straightline between points, empty space between points. no problem.

 

now. in case number two or three, what do you make of it? how can you make measurement of distance if one particle or both particles are nowhere to be found ? you must locate first the other particle to complete the measurement, but to locate it you have to wait for it to appear which requires another instant of time. so where is simultaneity between the two particles if they wont meet eye to eye? iow, to whom or what is simultaneity except to the idea of now. not for particles and not for events because objects dose not only occupy space they lso have temporal locations! i suspect that the non simultaneity of objects has something to do with multi dimensionality of spacetime. so i think space as multi dimensional rather than 3 dimensional. and to go towards ontology, we need to ask ourselves what are these dimensions represent.

 

This is just obvious. The whole bit about the "spacetime interval between" them assumes the "reality" of spacetime as something that expands, contracts, dilates, curves, has shape, etc., which ontology this thread is challenging, ergo not to be assumed as a given fro0m the git-go. See?

 

it is also obvious that behavior of particles in space does not follow what you would like them to believe that objects are things just floating in space. like a ship cruising the ocean when it shows that they are more "LIKE" vortices that appear here then there, gain and dissipate energy.

 

first let us understand that whether it is euclidean or non euclidean, let's agree that they are first and foremost coordinate systems that are both use in physics. QM uses euclidean N space coordinate system ( i think) and relativity non euclidean. the point is it is not entirely strange that lots of models use euclidean space. but what is common is they do their math in configured n-dimension space. so the challenge is not to dismiss the curving, dilating contraction and expanding of spacetime but to find further understanding as to what they mean.

 

what i don't understand is how do you arrive to say that real space is euclidean and time is an imaginary except as seeing it with the third eye. but of course euclid derived it from the everyday common sense experience as we still "feel" our space is today.

[Pyrotex]

...I keep hammering on the universal, omnipresent NOW... that the present is present universally, everywhere.

...Yup, everything happening now is happening simultaneously ... regardless of "spacial separation." And things that happened at different times were not simultaneous... This is just so obvious....

Michael,

well, I finally had to go out and read up on "ontology". I found a good primer here in Wikipedia, and then perused a few of its sublinks outward, until I felt somewhat comfortable with the word and its concept.

 

And here is what I'm left with, as per your quote above.

 

That "there is a universal, omnipresent NOW" is not refutable. Intuitively, it should be true. However, this leads to the question, "What is a NOW?" IOW, what is the physical referent (ontology) for the word "NOW"? If one takes this path (and I'm not suggesting you have to), then it leads to the conclusion that "NOW" is the name that Humans give to an experience of the local and immediate state of Reality. So, without a Human-like sentience to experience "NOW", there is no NOW. :eek_big: :lol:

 

I'm pretty sure that's not what you intended, and I prolly made some logical error. Back to my first conclusion.

 

That "there is a universal, omnipresent NOW" is not refutable. I will assume this is true as a given. Now, you say that "this omnipresent NOW is happening everywhere simultaneously".

 

This leads to the question, "What is simultaneity?" How do you go about demonstrating that any two NOWs are simultaneous? What does it MEAN for two NOWs to "be simultaneous"?

 

I cannot think of ANY way to answer these questions that AVOIDS the necessity of MEASUREMENT.

Another way of saying this, IMO, is to ask "What is the physical referent (ontology) of simultaneity?"

 

:eek_big: ;) :hihi: :confused:

[AnssiH]

But that its terminology offers you a way to draw correct predictions, does not mean it is the only valid map that can be built. Certainly it is possible to see the same exact raw data in completely different terminology, i.e. in terms of completely different ontological entities and their definied behaviour, still offering equally valid predictions.

First of all, great post AnssiH.

 

The paragraph above invokes my curiosity. Can you offer an example?

 

Thank you. Thanks to everyone else too for your kind words, I appreciate it. And sorry I'm a bit slow to reply. It is very time consuming for me to try and be clear, but I'd hate to contribute to the unintelligible noise with something quick and dirty.

 

I was referring to "relativistic spacetime ontology" as a "terminology for comprehending reality". Meaning; if you order the raw data in the "terminology" of relativity, you will see "relativistic simultaneity", you measure isotropic C, there is length contraction (as geometry is obviously also function of definition of simultaneity), and so on and so forth.

 

That measurement was understood in terms of relativity; the results are understood according to how relativity tells you they should be understood. But of course you can't really see the light while it is on its way, and your definition for "distance" and "time" (incl. simultaneity) gives you the meaning of "speed" (including the speed of that light), as per their algebraic relationships. Your definitions give you the means to interpret the results of your measurements.

 

If you think about a spacetime diagram that has got bunch of different simultaneity planes marked down, no observer is going to really see any of those planes directly. If you were to arbitrarily choose a single simultaneity plane and insist (without real justification) that it's the "real ontological simultaneity", then that definition would force you to say the speed of light is not isotropic anymore (as per the algebraic relationships between isotropic C and relative simultaneity). And that would actually change the way you'd see many things (like geometry).

 

Likewise, you could choose to insist that the ontological simultaneity plane is in any shape (instead of straight line), and draw out the rest of the definitions accordingly. Your worldview would probably be very complicated, but it would be self-coherent and it would still plot the exact same data; just your language and comprehension about what is happening looks very different.

 

Another way to put it; Note that the definitions of spacetime are algebraically associated to each others, so it should be pretty obvious that its entirely possible to change one thing in it, draw out the logical consequences to the associated definitions, and have something that is still self-coherent and still plots the same data (i.e. it still has got the exact same algebraic relationships embedded to itself).

 

That I think should be enough to convince anyone that it is indeed logically possible to understand reality in terms of multitude of different (but individually self-coherent) "sets of definitions" that each still plot the same raw data.

 

Sometimes you hear physicists say that "relativity is a convention", and I suppose that comment comes from the realization that the implied ontology is not really objectively justified as the actual logic is embedded simply into the algebraic relationships. It is geometrically very simple data tracking method, but does reality care about that? Don't think so.

 

But, as prediction machines, we certainly care about simplicity. From an epistemological standpoing simplicity is very important thing. So an interesting question at this junction would be, are there alternative, but still simple data plotting methods?

 

I've been convinced for a long time that an infinite number of valid worldviews can always be built to fit any raw data (because the essence of our self-made definitions is not in the individual definitions but in the relationships between the definitions), and even though I knew it to be quite trivially true that relativistic situations can be validly plotted with universal simultaneity, I had no idea whether it could be mathematically simple or not.

 

According to the findings of Doctordick, it is actually very, very simple. And mind you, his investigation has got nothing to do with insisting on a specific ontology, but it is instead entirely about the algebraic relationships that exist in our heads; everything he talks about is commentary on the epistemological reasons of why we understand reality this way. In this context, why we classify raw data into entities that behave relativistically.

 

The starting point of his analysis is just few completely immaterial requirements on any reasonable world model, springing from us being ignorant about the "real meaning" of the data*, and the requirement of self-coherence. When the impact of those requirements is expressed in terms of their effect on the probability of our expectations about the futures, a lot of modern physics seem to fall out from that relationship.

 

So for an exact answer on your question, try;

 

http://hypography.com/forums/philosophy-of-science/18861-an-analytical-metaphysical-take-special-relativity.html

 

I have not followed that through in detail yet, but I'm certainly meaning to. Skimming it through, looks not only valid, but at the end of the day seems like a reasonably expected result.

 

It can be little bit tricky to understand the philosophical justification for its starting point for anyone who looks at reality as naive realistic space and time. It should be pointed out here that the exact definition for space (and time) has got very concrete relationships to how we happen to define "objects". It is the behaviour of the objects that we have defined, that ultimately gives us the meaning of "space" (that's how we "see" space). The raw data to be explained does not have explicit objects to it; we just see certain patterns as "objects". We define what constitutes the identity of a "thing".

 

DD's work actually includes an explanation for the epistemological mechanisms that allow "objects" to be self-coherently defined from raw data... ...and lo and behold, the "common sense" definitions for "space" and "time", and also all the relativistic relationships appear to fall down from that self-coherence, without paying any attention as to what the content of the explained data is. The data simply needs to be ordered that way, whatever the content is.

 

Also it can be little bit tricky to understand the validity of that alternative data plotting (alternative to spacetime ontology), if you don't take the time to understand the terminology of this paradigm. If you are very much used to think in terms of relativistic spacetime, then understandably (and evidently) it is easy to mis-interpret many things there. Just be careful and take the definitions for what they are.

 

-Anssi

 

* "Meaning" itself is of course an epistemological concept and in my mind it's fair to say that devoid of human definitions, there is no meaning to anything. We assign a specific meaning to specific data pattern in order to draw predictions; some patterns are seen to be ontological objects persisting through time, as per our definitions of what constitutes an object. That is useful for drawing expectations about reality, without really knowing the ontological basis of any of it. (And btw leads to semantical understanding and whatnot, but this is really getting way too long already)

[AnssiH]

This should also answer your challenge, Erasmus. This is "the philosophy of science", specifically a thread challenging the ontological reality of "spacetime," not the empirical discussion of experiments and their results you keep throwing at me. Seems that you are totally ignoring Doctordick's and AnnsiH's comments (and mine) on this point of your ontological assumptions about spacetime. Your stuck on a 'show me your evidence' challenge, whereas the "burden of proof" for an assumed medium, spacetime, as above is on the theorists who invented it.

 

I can't be sure, but I think Erasmus is talking about logical consequences of specific definitions, and he is talking about it in terms of relativistic spacetime without necessarily meaning it as an ontological assertion. I am assuming so because of his post #424, as he seems to be asking you to focus on the logical consequences of your ontological standpoint, and quite correctly points out that it is possible to draw out those logical consequences. So, like DD, I would say Erasmus is quite spot on with that comment.

 

The problem with communication here is, that even when someone has stopped looking at relativistic spacetime as an ontological thing, they tend to persist to talk about physics with that terminology because it is practical. So, communication about ontology can become somewhat confusing as you never really know how people mean their assertions.

 

Your commentary is not very clear either. At least I get the feeling that you are insisting on some ontological starting point simply out of "common sense", in which case you need to think about what is meant by common sense and where you get it.

 

For example, you talked about distance measurements. But of course you have to first carefully define all the aspects of what it means to measure some distance, and different definitions simply lead you to different results.

 

The funny thing with relativity, as you well know, is that by its definitions the distance is seen as a function of the velocity of the observer. I think the real purpose of this thread is to talk about, what is the ontological meaning of such a circumstance (including the circumstance regarding simultaneity), yes? The answer has been voiced few times already :hyper:

 

Btw, to improve your communications, perhaps try E-prime?

 

-Anssi

[Michael Mooney]

Michael,

well, I finally had to go out and read up on "ontology". I found a good primer here in Wikipedia, and then perused a few of its sublinks outward, until I felt somewhat comfortable with the word and its concept.

 

And here is what I'm left with, as per your quote above.

 

That "there is a universal, omnipresent NOW" is not refutable. Intuitively, it should be true. However, this leads to the question, "What is a NOW?" IOW, what is the physical referent (ontology) for the word "NOW"? If one takes this path (and I'm not suggesting you have to), then it leads to the conclusion that "NOW" is the name that Humans give to an experience of the local and immediate state of Reality. So, without a Human-like sentience to experience "NOW", there is no NOW. :) ;)

 

Well... I keep going back to the actual existence of the cosmos, objectively, in and of itself, independent of "relative perspectives", whether by sentient observers or theoretically. If you review what I have said about the reification of time (debunking its "reality quotient" as an entity/event itself (which can speed up or slow down... or have a beginning and end...) Both in this thread and at the end of the "What is Time" thread, you will see how I arrived at the conclusion that time is a human artifact. (This does not deny that all motion can be said to happen with an assigned "duration", as in velocity, obviously.)

So, all this is getting to the ontology of "time" as the concept of "event duration" while actually, really, absolutely truly... "It" is always now... everywhere, ongoing, always!.... Honest!;)

So there is no "physical referent" per se, for The Perpetual Omnipresent Present

"It" is not a thing. When we say "It is raining," there is no physical referent for "It." Rather it just means that rain is happening. Likewise, all "happening" is happening right now[/i That's what [i]is means, as contrasted with was[/i or [i]will be.

 

I'm pretty sure that's not what you intended, and I prolly made some logical error. Back to my first conclusion.

 

That "there is a universal, omnipresent NOW" is not refutable. I will assume this is true as a given. Now, you say that "this omnipresent NOW is happening everywhere simultaneously".

 

This leads to the question, "What is simultaneity?" How do you go about demonstrating that any two NOWs are simultaneous? What does it MEAN for two NOWs to "be simultaneous"?

 

"Two Nows" is a misconception of the universal Present, as above. Now is omnipresent... not one "now" here and another "now" there. This is the misconception of relativitiy's "time frames" as being actuall different "nows" in different places. Like "now" for the sun is also "now" for the earth, but we will not see the light of the sun's "now" for over eight more minutes. Therein lies the fallacy. Not two different "nows" but a time lapse in conveyance of the light from there to here.

 

I cannot think of ANY way to answer these questions that AVOIDS the necessity of MEASUREMENT.

Another way of saying this, IMO, is to ask "What is the physical referent (ontology) of simultaneity?"

All phenomena in the universe exist and are happening all by themselves, whether sentient beings anywhere are "measuring them or not. As with the Present (Now), there is no physical referent component of simultaneity, as the word simply denotes that events are happening at the same time, i.e., either "right now" or sharing the same moment, no matter their location in space, in the past.

 

:hyper: :naughty: :( :(

 

Hope this clarifies what I'm talking about.

Michael

[maddog]

Maybe you are not clear on what *ontological* inquiry into the *reality* of "spacetime* in the "real world" means. Yes. I agree that it is just a "construct" in service to relativity theory. I've affirmed 3-D space and event duration (time) maybe 100 times in this thread. So, unaware of this you repeat the obvious.

Though you didn't mention Ontological as your criteria basis for the original question of "what is spacetime", I will engage you.

To study up I went an looked it up (just so as not to be misquoted):

 

Ontology - Wikipedia, the free encyclopedia

 

refers Ontology to being the study of "being, existance or reality in general".

 

Spacetime is not an entity so no being is going on. Is spacetime per se present in the

real world. I would say Not as you think "Real World" any more than a coordinate

system I lay on a map is. They are equivalent.

 

... the challenge of this thread... the ontology of "curved space", etc., etc. I have asked for commentary on the ontological assumptions behind "spacetime"...here again is the epistemology, assuming that spacetime need not be question... being just a "construct" after all. You totally miss the point of my inquiry/challenge inb this thread.

I am still read what I think in #436 posts to this that I know what your point is other than throwing "ontology" or "epistimology" around a lot without being all that clear. You ignore the science yet expect us to answer a deep philosophical question and do so without any such construct. I find that odd.

Quoting from you in post #1

What is "spacetime" really?

In answering, you may correctly assume that I have thorougly studied the background of the "spacetime" component of relativity theory. Yet the actual nature of the "medium" (or whatever it is *supposed* to be) has never been explained to my satisfaction.

So the "matrix" is a "curved concept of space." Ontologically, what, in the real world, is "curved?"

Again, the coordinate system itself -- aka Differential Geometry.

Yes you could... until the ontological referents in the real world are made explicit.

Already answered.

"The fabric of mathematics" must connect with the concepts it purports to elucidate, and these concepts must then be explained as accurate descriptions of the "real world. "Most scientists"... all, I think so far contributing to this thread, neglect the last two steps... and just assume the matrix and its math have counterparts in the "matter/energy matrix" of "the real world... ignoring the ontological question ("spacetime??" completely!

The mathematics is intended to always relate back to something describing what is in existence (your) "Real World". String Theory to date may be one exception in that there mathematics has outstripped what underlying theory can describe. I am not ignoring

any ontology here. I am using mathematics as a tool to describe what we see in this

real world.

I think you have math as primary reality and that which it attempts to describe as secondary. Par for the course for most mathematicians. You have screened your reading of this thread through exactly this error/bias. If "spacetime" is just a metaphore/concept then what is it that "curves" etc. in the real world the concept attempts to describe?

I may have a bias -- that is what I know of physics and mathematics and logic.

They are tools for the trade.

Then I asked how such a "triangle" on a curved slice of earth's surface (apex at pole and base on a segment of the equator) is evidence for "curved space" as an entity other than surfaces of geometric shapes. No reply.

I accept your concession. I was under the impression you disagreed. The curved space is the surface of our earth's surface when looking at the representation of a

2-surface mapped onto a 3-sphere.

Please go to the "geometry lesson" link which Watcher provided above. It is exactly what I said... an enlargement of a cube posing as an illustration of a fourth spacial dimension. This is the kind of argument I'm getting here for the validity of "non-Euclidean space."

May be you can point out which post# that would be, I'm a bit busy.

Rereading this maybe you are referring to a hypercube as the frame of a cube translated

through space -- creating a fourth dimension. This is one way.

Ontologically speaking, one must first establish that space is *something* that can curve, rather than being emptiness (in between "things.) Then one is philosophically "allowed" to theorize what *shape* this "fabric" or whatever might be. Do you get this point or not?

Actually, I think the ontological aspects are unessecary. Non-Euclidean Geometry comes

about by not assuming all the axioms that Euclid did. In particular the notion of parallel

lines never crossing. This cannot be proved and is an axiom of Euclid. This however

does not make Euclid wrong (nor right). This is just a different Geometry than Euclid's.

So it is a given that Euclidean is proven wrong and non-Euclidean the correct description of reality? This totally avoids the ontological questions I am here asking. So Einstein and Minkowski invented "sapcetime," and who would question such genius.?

dAnyone can be questioned -- If said theory doesn't agree with the facts. Aristotle was

questioned eventually. Gallileo eventually came up with a better description of motion.

Newton extended on that. Einstein himself eventually questioned Newton's ideas.

I don't feel anyone is so sacrosanct. All must allow their theories to bear the crucible

of evidence gathering and checking of facts.

See my comments on the "hole argument" above. I have lots of notes on the link that one came from if you want to go into detail about the ontology of the conceptual/ model/map matrix as contrasted with the "matter/energy matrix" of the real world.

But the ontological difference will elude you, if I read your bias here correctly, as above.

I am not sure what you are talking about here. Hole ? -- Black Hole ?

You could, but I have already agreed in principle that all of the above are well established aspects of relativity theory, and you clearly are not aware of what I accept, as for instance the examples above, and what I reject, as for the several hundredth time, the reification of "spaceitme" as a required axiom of relativity theory. Whew!

Reification definition (word I do not often use) as "process of misunderstanding an abstraction as a concrete entity" (borrowed from Ansewers.com).

If I understand this right, I think you reified "spacetime". As I understand it -- this is an

abstraction, and a useful one.

What "higher dimensions?"... really... as per my challenge to non-Euclidean space as a basis of the medium "spacetime." I asked that respondents know what such "dimensios" actually are in the real world and give clear evidence/arguments for their actual existence. Just saying " higher dimensions matrices" does not in fact establish their ontological vaslidity, but in fact simply *assumes* such validity without addressing the ontology.

That actually is a good question. One I don't have a definite answer for. Best I can say

is "depends".

You might have asked if this answers my questions rather than assuming what you can not know about me. No it does not. I have exposed that you are a novice in ontology, totally clueless about what this thread is actually challenging... yet you assume (you *assume* volumes without ontological examination!) that you have set me straight.

Novice maybe in that I haven't yet read a complete book on Heidigger. I have begun to

think that you are some reincarnation of Arisotle himself!

No judgmental bias there! Of course your "take" is the last word on reality here, tho you are unfamiliar with the disciplined study of "What is real... What actually exists?)

I ask myself that every day. Or more fundamentally, what is the basis of existence

in reality. I am not sure there actualy is a "real world", so I leave it there.

How does a "construct" ("spacetime") "put real-world constraints" on causality. You so obviously have the cart before the horse here, that I don't think any ontological argument, as above can make it through your screen of pre-conceptions.

To answer that question you would have to understand some of the physics which you

shun. Causality is constraint by spacetime though I ammend by only what is visible.

 

maddog

[Michael Mooney]

Watcher:

now. in case number two or three, what do you make of it? how can you make measurement of distance if one particle or both particles are nowhere to be found ? you must locate first the other particle to complete the measurement, but to locate it you have to wait for it to appear which requires another instant of time

 

I am becoming frustrated with the huge communication gap between us.

 

For general reader clarity, you are referring to your following statements:

if you take a snapshot of two point particles in space, there is a probability that you would capture 1. both in a picture 2. only either one in the picture 3. none. if you take lot of series of snapshots, then and only then you can know what is happening. what do you make of it.

My "snapshot" was not looking for missing geometric (virtual) points or objects or waiting for them to appear. The "snapshot", as I already said, was a device through which to focus on "the actual distance between the two loci at a given moment" rather than the "spacetime interval" (sic) between one locus where it was a year ago and the other locus where it is now.

It was *my snapshot* and I'll just say to make the point as simply as possible that it was taken equidistant from two "real objects in empty space" and both objects were already clearly in the picture. I don't care what units of measure are applied. Since you and I are Earthlings, "earth diameters" (ED) will do as a meaningful reference. So, there are a certain exact, fixed number (and an exact fraction) of ED between... say earth and sun... just to give the argument some substance.

Of course this *actual distance* changes with the out-of -round earth orbit, as earth actually moves closer and further from the sun. The exact distances, both max and min are well known and published... as in a link I shared quite a few pages ago.

This distance does not change with the dfferent relative velocities or fixed positions of different cameramen or with aliens approaching our solar system at near lightspeed with telescope focused on both earth and sun. (Thanks to Pyrotex for this image.) The point is that *relative perspective* has no effect whasoever on the actual distance between sun and earth.

 

Hope this clarifies my "snapshot" illustration.

 

Michael

[maddog]

Sounds like logic, but what is the logical necessity? There is none. It is nonsense. All events are happening right now simultaneously, regardless of how far apart they are. An event that happened last year is not happening now. Uh, yeah, ok...

Erasmus:

If the speed of light is constant for all observers, then this is deductively not possible. In special relativity its not just that events are observed in a different order, its that the events must have happened in a different order

With what part of the above are you disagreeing? I agree that the speed of light is constant for all observers. So "this" what is deductively not possible?

 

I keep hammering on the universal, omnipresent NOW... that the present is present universally, everywhere.

Your quote above would only be that way to a massless particle like a photon. Those

kinds of particles have no time sense.

Erasmus also misunderstands SR.

So what one relative perspective can "see" relative to another is well and accurately handled by relativity. This does not even address the ontology of universal simultenaity... that the present is present everywhere... right now.

No it does not. Omnipresence per se is godlike so physics does not even attempt to represent it in any way.

Modest has "inertial frame of reference" as the only and absolute reality. He can not comprehend universal simultenaity... that Now is omnipresent everywhere. It just doesn't register for him as reality now everywhere transcending his central importance of time, specifically the time it takes information to travel through space... which is obvious. His "if" above makes simultenaity a special case, whereas it is the universal NOW. Then he affirms the obvious: that things that happened in the past or will happen in the future are not in fact happing now... not simultaneous.

Inertial frames of reference are the mechnanism of choice if the desire is to model the equations of motion of objects within this universe.

Yup, everything happening now is happening simultaneously ... regardless of "spacial separation." And things that happened at different times were not simultaneous or are not simultaneous with what's happening now... everywhere/anywhere.

Everything happening now that means anything is what you can observe "right now".

Taken to it's extreme: then nothing is happening right "now" -- because it already happened. You cannot speak with any authority on what is happening in the Andromeda galaxy as it is more than two million light years away. Something is happening. Just no knowledge of what.

 

Therefore meaningless.

 

maddog

[Pyrotex]

....Inertial frames of reference are the mechnanism of choice if the desire is to model the equations of motion of objects within this universe.

 

Everything happening now that means anything is what you can observe "right now"....

Maddog,

I think I am getting a glimmer of what it is that Michael is getting at.

 

In the "ontological view" of the Universe, the existence of each and every particle, photon, field and object is totally independent of observation. That is, the reality of those things is not affected by whether or not they are being observed or measured.

 

If there's nobody in the forest to hear, the falling tree STILL makes a sound! :)

 

Everything exists as it is, wherever it is, independent of subjective measurement or judgement of any kind whatsoever. And this "existence" occurs in the everywhere-eternal Now. The universe doesn't need us to tell it what it is. End of the "ontological view".

 

Correct me if I'm wrong, Michael.

 

Aside from that --- in addition to that --- separate from that, we have humans. Us. And we observe the universe and try to understand it. We derive equations, such as SR, to "explain" what we observe. We create concepts such as "spacetime" and "elapsed time" and "local time" to, again, help us understand what we experience and observe.

 

But, says the "ontological view", our observations and minkowski spaces and equations and telescopes and thought experiments do NOT IN ANY WAY have ANY AFFECT on the ontological reality of the universe. Our observations cannot cause a distance to change or a mass to increase or an elapsed time to slow down. On the other hand, this all means that we cannot observe the ontological universe as it really is.

[watcher]

Michael,

 

Likewise, all "happening" is happening right now[/i That's what is means, as contrasted with [i]was[/i or will be.

 

a happening to be a happening has 4 components.

1. energy

2.mass

3.space

4. time

 

so happening is the interaction of mass and energy in space and time.

to say that a happening is happening in the now is totally redundant.

 

the statement there is only a happening should suffice.

to place this happening in the "NOW" is already an overlaid of your mind.

in reality there is no now, there is only an instant by instant flow.

proof is the moment you say NOW, that moment was gone already.

 

"Two Nows" is a misconception of the universal Present, as above. Now is omnipresent... not one "now" here and another "now" there. This is the misconception of relativitiy's "time frames" as being actuall different "nows" in different places. Like "now" for the sun is also "now" for the earth, but we will not see the light of the sun's "now" for over eight more minutes. Therein lies the fallacy. Not two different "nows" but a time lapse in conveyance of the light from there to here.

 

relativity does not refute that the sun and earth exists simultaneously as of this moment as we speak. it only says that the sun's existence is related to earth's existence in all aspect. in the microworld, this relation is more pronounced. simultaneous existence are not for all objects. so the now or the instant of one particle is not the same now for another object. but if you say that the instant of one particle that exists and the instant that the particle does not exist is the same instant that exists in the now, you are correct. but that is pure subjective.

 

All phenomena in the universe exist and are happening all by themselves, whether sentient beings anywhere are "measuring them or not.

 

this is a true statement but then you added this one:

"events are happening at the same time, i.e., either "right now" or sharing the same moment"

again you make idea convulated. the passage of moment to moment is already incorporated to the thing called "happening". so again to say that happening is happening now is a redundancy. why? because when we say there is only a happening, all frame of reference for the sake of discussion are being ignored, but when you insists that all this unreferenced events are happening now, you pinpointing the happening to your subjective point of view. your time frame!

 

As with the Present (Now), there is no physical referent component of simultaneity, as the word simply denotes that events are happening at the same time, i.e., either "right now" or sharing the same moment, no matter their location in space, in the past.

 

i am not discounting your ability to see things differently about the universe. but as you have already realized by now, what is being questioned by so many here is the logical consistency of your interpretation of your cosmic observations. as i have already explained to you, the present moment is not the same present moment for all particles/frame of reference/ observers. and you unavoidably is also an observer.

 

now suppose there is an observer that can go with the flow of time, this will mean that it will be present in every instant of time and can observe every happening in the universe. this is what you probably mean by saying that everything is happening in the now. right?