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What is "spacetime" really?


Michael Mooney

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(Note: I don't yet know how to make quote boxes with selected pieces from previous posts.)

 

Modest:

"The fundamental units of time, space (distance), and mass are arbitrary. As you say, there are seconds, minutes, days, years, etc. Putting units of time and space together into a coordinate system gives you a mathematical model that we can call "spacetime". I refer here to the model of reality and not reality itself. On this coordinate system we can model things like kinematics or electrodynamics and they should work regardless of which units of measure we decided to start out with. "

 

So, If "spacetime" is just a mathematical coordinate system, how is it that "it" has become *reified* into something that has curvature, geometry and shape?

We can certainly describe trajectories as vectors of a wide range of objects (including photons and such) without interjecting the superfluous concept of "curved spacetime."

 

Do you "buy in" to non-Euclidean space such that the shortest distance between two points is no longer a straight line? Even with the "line drawn on a sphere" model, the shortest distance between the two end points remains a straight line *through the arc of the sphere*... a straight "rod" shoved through the "globe" from one surface point to the other.

 

How about parallel lines? How is it exactly that they "meet" in non-Euclidean geometry. By mental gymnastics? How about in the "real world?"

 

Can you conceive of space being emptiness... between "quanta" on micro-scale and between masses and mass clusters of all macro-scales?

 

Can you describe an "end of space?" Of course not. Space as emptiness (filled with whatever beyond the cosmic event horizon... limited of course by lightspeed)... *must* be infinite. What would be beyond any imaginary boundary but more space... infinite space?

 

How then would space have "shape"? (Obviously the contents of space have shape.)

 

Finally (for this reply) you misunderstood my *aside* on the Bang/Crunch cosmological model.

As below...

 

MM:

"An aside:

What other model [besides an oscillating, "Bang/Crunch cosmos] accounts for the origin of cosmos... if "something out of nothing" is taken to be as absurd as religious "creation-ism"... where it all came out of "God's magic hat... a myth without scientific credibility?"

 

Modest:

"Big bang theory doesn’t describe “something out of nothing”. The theory doesn't make any claims regarding what (if anything or nothing) there was before (if there was a before) the big bang. Neither does the big bang theory “account for the origin of the cosmos”. Other theories such as loop quantum cosmology are attempting to answer these questions, but they are beyond the scope of the current big bang theory."

 

I was asserting that the only cosmology which can explain "where it all came from" is the two phase model, oscillating perpetually from expansion through gravitational reversal to implosive contraction into the primordial ball of all cosmic material, and then exploding back out again.... perhaps like a cosmic "juggling act" rather than all cosmic material exploding at once and then imploding all together.

This model operates in Euclidean space as actual material expanding into *empty space* and later contracting via a "gravitational net back from deep space. But this was, after all an aside... just the most *reasoable* cosmology I've come across. And it doesn't require a mentally fabricated "fabric, spacetime."

 

Gotta go again.

Michael

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duplicate post... attempting to delete

****! It deleted both posts,,, had a good hour into a reply to Modest.

I give up.

 

To avoid this in the future, it's recommended that you type your reply in notepad and copy and paste it to the site when you are finished. This will save you from experiencing time-out issues such as this.

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duplicate post... attempting to delete

****! It deleted both posts,,, had a good hour into a reply to Modest.

I give up.

 

I was deleting your second post while you were editing the first. By coincidence then, they both were axed. It's not a problem, I just undeleted the the one that I deleted—all's well that ends well :D

 

My question was labeled a philosophical one, specifically ontological, and the thread was moved to the "Humanities" section, "Philosophy of science."

 

There is no negative connotation with a thread being in philosophy of science—it’s simply appropriate in this case. The questions and answers forum wasn’t a good fit because it is intended for quickly referenced answers that end up being no more than 2 or 3 posts long. I didn’t see that happening in this case. Any kind of sustained debate isn’t a good fit there.

 

Your thread belongs here because it is fundamentally a philosophical question. It is the nature of philosophy of science to explain and understand the implications of scientific theories. It’s a very important part of science.

Philosophy of physics is the study of the fundamental, philosophical questions underlying modern physics, the study of matter and energy and how they interact. The main questions concern the nature of space and time, atoms and atomism.

(Note: I don't yet know how to make quote boxes with selected pieces from previous posts.)

 

I've added quote tags to your previous post. To quote another member's posts inside your response you can click the button marked "quote" underneath their post. That will then open up a reply that contains their entire post inside "quote tags".

 

Quote tags are just like quotes. If you wanted to quote Einstein you could do either of these two things:

  1. "God doesn't play dice with the universe"
  2. God doesn't play dice with the universe

The bottom one will render like this:

God doesn't play dice with the universe

 

There is also a button that quickly adds quote tags you'll see when writing your post. It looks like this:

Select the text you want quoted then hit that button.

 

 

Now that the procedural stuff is out of the way...

 

Michael,

 

You continually assert that space is just emptiness and therefore cannot have properties such as being curved. This is wrong (or at least unsupported) for a few reasons.

 

General relativity is not the only theory of physics that demands space is not just emptiness. QFT (quantum field theory) also describes fields that are present in all of space. This culminates in theories such quantum electrodynamics which have enjoyed enormous success. QED is tested accurate to ten parts in a billion. As wikipedia says: "This makes QED one of the most accurate physical theories constructed thus far". For you to declare that space is "just emptiness" is not just disagreeing with General Relativity—it's disagreeing with many physical theories in modern science.

 

The nature of emptiness as you envision it is a disconnection between entities. If nothing but emptiness (with no properties) exists between things that are spatially separated then simple thought experiments go awry.

 

For example, the earth is spinning compared to the stars in the sky. Either the earth spins and the stars remain fixed or the earth remains still and the stars rotate around the earth. If the earth is an island universe unto itself with no fundamental connection to those stars then there should be no way to determine which is the case. But, the earth does know it's spinning compared to the stars.

 

The earth has angular momentum and centrifugal force that is quite real. It is not just a mathematical construct. When things spin compared to the "background stars" or the background of "spacetime", mass is accelerated away from the axis of rotation. But, if such objects were disconnected from the rest of the universe there would be no way for them to know they are spinning or not. They can't very well spin compared to nothing. In the language of General Relativity, mass there affects inertia here. [see Mach's principle]

 

So, experimentally, we know there is some connection between mass here and mass there. It can't be nothing—it must be something.

 

You also assume incorrectly that if space is "just distance" then it is Euclidean. In other words, if space has no properties then it will be measured in an Euclidean way. But, saying space is Euclidean is giving it a property. Assuming parallel lines will never cross or diverge is no more of an assumption then assuming they will cross or diverge. There's nothing about Euclidean geometry that makes it the a priori first choice in describing how the universe works.

 

We certainly do measure distance and duration in a non-Euclidean way. If you emit a laser at the top of a building it will have a different frequency as when you detect it at the bottom. The measurements of distance and duration are different at the top as at the bottom. This was predicted with startling accuracy (and is still described best) by the 10 differential equations of general relativity. [see gravity probe a]

 

Therefore, to assume that that rules of the universe demand euclidean space and time is conjecture that appears not to be supported by evidence.

 

My question was and is very specifically inquiring as to whatever it is that mainstream science now posits as something (whether or not an actual existential *entity*) that is consistently described as being bent or curved or spherically enclosing a point ("singularity") or a massive ball (black hole)... having an actual "geometry" as if it were a malleable (as above) medium.

 

This question has been answered in unanimous agreement. Spacetime is not a malleable medium. It is not made of matter and it is not tied to a preferred reference frame. It is non-mechanical in nature. The analogies that you bring up are just analogies. They mean to relay characteristics of the theory in an easily envisioned way. They do not mean to imply anything ontological about any aspect of the theory.

 

In a general sense, the variables of space and time in GR are the same as the variables of space and time in special relativity. They are distance and duration. They are 'whatever' clocks and rods measure. Why these variables function in a way that is described by GR (in a way that is loosely described as curved) is a very interesting and difficult question that is at the heart of our discussion. I think it's a very thought-provoking and interesting topic. :phones:

 

~modest

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Modest,

Thanks for the technical pointers and restoring my deleted post.

 

As to whether my title question is philosophical... seems if science continually refers to the "curvature of space" as distinct from the curvature of trajectories of objects traveling through space, then the burden of explaining what it is that is curved (besides the obvious trajectory of objects) is upon the theorists positing the said curvature. (See the Nikola Tesla quote in my post two removed above.)

 

Does the agent of gravitational attraction also belong in ontological debate?

 

Likewise concepts like "time dilation." I went to some length to contrast the ongoing universal present with the "elapsed time" component of equations central to both SR and GR, but you have not addressed the above at all... nor the six pointed questions in my last post to you. I also spoke of the differences between *clocks slowing down* via the force of changes in inertia and "time slowing down."

 

If the argument is that time is that which clocks measure, it doesn't even address the inquiry into what forces might actually be at work slowing the clocks down... be it the slowing rate of radioactive decay in cesium (as in some atomic clocks) or the friction on the flywheel of a submerged wind-up clock. Surely you are not saying that time slows down under water too. It is after all, what the clock is measuring under altered conditions.

 

Then you argue as follows: (and I will comment in context in bold for easy reference)

 

You continually assert that space is just emptiness and therefore cannot have properties such as being curved. This is wrong (or at least unsupported) for a few reasons.

 

General relativity is not the only theory of physics that demands space is not just emptiness. QFT (quantum field theory) also describes fields that are present in all of space. This culminates in theories such quantum electrodynamics which have enjoyed enormous success. QED is tested accurate to ten parts in a billion. As wikipedia says: "This makes QED one of the most accurate physical theories constructed thus far". For you to declare that space is "just emptiness" is not just disagreeing with General Relativity—it's disagreeing with many physical theories in modern science.

 

I consider gravitational fields and electromagnetic fields operating across empty space as more reasonable than saying space is not actually empty but rather filled with some unknown medium/aether/whatever and calling it spacetime.

 

The nature of emptiness as you envision it is a disconnection between entities. If nothing but emptiness (with no properties) exists between things that are spatially separated then simple thought experiments go awry.

 

It seems more scientifically honest to admit that we don't yet know how "action at a distance" works than positing a mystery fabric which no one can explain... i.e., "what it is." "Action at a distance" including not only gravitation... which travels at lightspeed but is *constant*... no gaps waiting for the next "packet" of G-force... but also "entangled particles" in the quantum physics experiments. No one knows the medium of information exchange between them either.

 

For example, the earth is spinning compared to the stars in the sky. Either the earth spins and the stars remain fixed or the earth remains still and the stars rotate around the earth. If the earth is an island universe unto itself with no fundamental connection to those stars then there should be no way to determine which is the case. But, the earth does know it's spinning compared to the stars.

 

The "fundamental connection" is gravitation. There is no reason to posit the obvious absurdities of your "either/or" above or your "if/then." We still don't know how exactly the alignment of Sirius A and B every 50 or so years slows down Earth's rate of rotation measurably, but it happens, and the slowing happens in synch with observation of the passing alignment, i.e., the gravitational *change* travels to and effects Earth at the speed of light.

 

The earth has angular momentum and centrifugal force that is quite real. It is not just a mathematical construct. When things spin compared to the "background stars" or the background of "spacetime", mass is accelerated away from the axis of rotation. But, if such objects were disconnected from the rest of the universe there would be no way for them to know they are spinning or not. They can't very well spin compared to nothing. In the language of General Relativity, mass there affects inertia here. [see Mach's principle]

 

I am not disputing earth's angular momentum and centrifugal force. Again the emptiness of space allows gravitational, electromagnetic and quantum "fields" to travel *through space* without it being "filled* with the mysterious medium "spacetime."

 

So, experimentally, we know there is some connection between mass here and mass there. It can't be nothing—it must be something.

 

Gravitation is a field which acts as per the universal law thereof, "directly with massiveness and inversely with distance"... Just like Newton said. He didn't like "action at a distance" either, but the equations still work, as all astronomers and "rocket scientists" know. Maybe further investigation of the "dancing partners", the entangled particles mentioned above will shed new light on "action at a distance" *through empty space.* It is not mandatory that science *fill it with something indescribable* like "spacetime" in the meantime.

 

Thanks for the conversation.

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Michael,

 

I've just read through the thread, and I sympathise with your plight. What is spacetime? Some very good answers have been given, but I'll add some which, I hope will help.

 

Spacetime is an abstraction, it does not actually exist. What exists are physical entities. So spacetime can be looked on as a metaphor for the relationships betweens entities. As you rightly say, since spacetime does not actually exist, it cannot have properties like being curved. However, as Modest has pointed out, the idea that spacetime is curved is just an analogy.

 

You are wrong in assuming that because spacetime is an abstraction, this means that space must be linear, and time (now) must be universally the same. Hence it's just the trajectory that is bent, or the clock that is running slow. There is no reason why the fundamental relationships have to be linear and universal. That is a reasonable assumption, but is an assumption. Special and general relativity are based on the assumption that the velocity of light is the same in all frames of reference. That too is a reasonable assumption, but it leads directly to the conclusion that the temporal and spatial relationships between physical entities are not linear. And, as Modest has pointed out, there is evidence to support this view.

 

However, what I find difficult to understand about spacetime is the way that spatial distances and time intervals combine to form spacetime intervals. The spatial distancess combine according to pythagoras's law, so the square of the spatial distance is equal to the sum of the squares of the distances in the three spatial dimensions. I.e. d2 = x2 + y2 + z2.

Where d2 is the square of the spatial distance, and x2, y2 and z2 mean x squared etc...

 

But the square of the spacetime interval is equal to the difference between the squares of the spatial distance (in light seconds) and time interval (in seconds). I,e, s2 = d2 - t2 (if d is greater than t) or s2 = t2 - d2 (if t is greater than d).

Where s2 is the square of the spacetime interval (in seconds or light seconds), d2 is the square of the spatial distances (in light seconds), and t2 is the square of the time interval (in seconds).

 

Why is this? The answer "well the maths works out that way" does not seem to me to be philosophically satisfactory. Also, if the combined spatial distance and the time interval are the same (when measured in light seconds and seconds respectively) the spacetime interval is zero. What does that mean? Why should two events that are two light seconds apart that happen two seconds apart have a spacetime interval between them of zero? Does this mean that they happen at the same place (i.e. are co-located)? No. Does this mean that they happen at the same time (i.e. are simultaneous)? No. What does it mean???

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Why should two events that are two light seconds apart that happen two seconds apart have a spacetime interval between them of zero? Does this mean that they happen at the same place (i.e. are co-located)? No. Does this mean that they happen at the same time (i.e. are simultaneous)? No. What does it mean???

 

objects and space are discrete.

space/mass and time toggle out of existence alternatively.

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But the square of the spacetime interval is equal to the difference between the squares of the spatial distance (in light seconds) and time interval (in seconds). I,e, s2 = d2 - t2 (if d is greater than t) or s2 = t2 - d2 (if t is greater than d).

 

Once you pick a sign convention, the equation doesn’t change regardless if [imath]t^2 > d^2[/imath] or [imath]t^2 < d^2[/imath]. If you’re using [math]s^2=t^2-d^2[/math] and the resulting [imath]s^2[/imath] is positive (ie [imath]t^2 > d^2[/imath]) then the interval is time-like and there can be a cause/effect relationship between the events. If it is negative ([imath]t^2 < d^2[/imath]) then the interval is space-like with no cause/effect possible . If it’s zero then the distance is light-like (or null) which defines the light cone.

 

Why is this? The answer "well the maths works out that way" does not seem to me to be philosophically satisfactory.

 

The spacetime interval is a side effect of how we map space and time into a useful metric (Minkowski space). It’s useful because the spacetime interval is invariant—all observers agree on it regardless of their frame of reference. It’s easy to see that a null interval is invariant. It’s the same as saying all observers agree on the speed of light.

 

So, your question (philosophically) is probably equivalent to asking why the the speed of light is the same for everybody and maybe also having to do with the isotropy of spacetime.

 

There's a lively debate in 15674 where Erasmus advocates the normal Minkowski (-+++) while Doctordick proposes (++++).

 

~modest

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Thanks for your reply, Jediasoul.

I agree with your paragraph as follows:

 

Spacetime is an abstraction, it does not actually exist. What exists are physical entities. So spacetime can be looked on as a metaphor for the relationships betweens entities. As you rightly say, since spacetime does not actually exist, it cannot have properties like being curved. However, as Modest has pointed out, the idea that spacetime is curved is just an analogy.

 

I am directing this reply to your second paragraph below. (The rest of your post is technical math, to which I see Modest has replied. You two can hash that out, as I am not a mathematician.)

 

You are wrong in assuming that because spacetime is an abstraction, this means that space must be linear, and time (now) must be universally the same. Hence it's just the trajectory that is bent, or the clock that is running slow. There is no reason why the fundamental relationships have to be linear and universal. That is a reasonable assumption, but is an assumption. Special and general relativity are based on the assumption that the velocity of light is the same in all frames of reference. That too is a reasonable assumption, but it leads directly to the conclusion that the temporal and spatial relationships between physical entities are not linear. And, as Modest has pointed out, there is evidence to support this view.

 

I am just trying (and failing) to make sense of "spacetime" as a bendable entity/medium or what I have been calling its reification into a malleable medium, since sceince documents consistently refer to it as curved, expanding, etc.

I have yet to see why a common sense Euclidean model of cosmos and parts thereof will not work without the invocation of (what appears to me to be) non-Euclidean nonsense as models of time, space, timespace and cosmology in general. With the above in mind, I asked Modest several very specific questions (transcribed below) which he chose not to answer.

How about you?

 

 

MM questioning Modest:

So, If "spacetime" is just a mathematical coordinate system, how is it that "it" has become *reified* into something that has curvature, geometry and shape?

We can certainly describe trajectories as vectors of a wide range of objects (including photons and such) without interjecting the superfluous concept of "curved spacetime."

 

Do you "buy in" to non-Euclidean space such that the shortest distance between two points is no longer a straight line? Even with the "line drawn on a sphere" model, the shortest distance between the two end points remains a straight line *through the arc of the sphere*... a straight "rod" shoved through the "globe" from one surface point to the other.

 

How about parallel lines? How is it exactly that they "meet" in non-Euclidean geometry. By mental gymnastics? How about in the "real world?"

 

Can you conceive of space being emptiness... between "quanta" on micro-scale and between masses and mass clusters of all macro-scales?

 

Can you describe an "end of space?" Of course not. Space as emptiness (filled with whatever beyond the cosmic event horizon... limited of course by lightspeed)... *must* be infinite. What would be beyond any imaginary boundary but more space... infinite space?

 

How then would space have "shape"? (Obviously the contents of space have shape.)

 

For reference to the cosmological model which *does* make sense to me, please review my "aside* on the oscillating, "Bang/Crunch" model above.

This is about actual "stuff" expanding out from the "bang" into empty space in all directions... just like a fireworks display... and eventtually being caught in deep space by the cosmic "gravitational net" (assuming we find enough matter for the required critical density... more 'strange matter' being discovered all the time)...and pulled back (imploding into a "crunch") for another round. Note also my reference to a "cosmic juggling act" conwsisting of many smaller "bangs" and many phases of incoming matter into multiple "crunches."

 

Finally, do you have any comment on my take on the present (now) being *now everywhere simultaneously*, ongoing always and not naturally segmented into "time units?"

This is a perspective transcending relativity and local perspectives and applicable to the the whole Bang/crunch cosmology, i.e., not about what who can see when... depending of course on lightspeed, the basis of relativity theory.

It could be called a "thought experiment" from cosmic perspective... that "it" is now everywhere always, ongoing perpetually, eternally with no real beginnings or endings. (And it solves the problem of where "it all came from in the first place, there being no "first place" but an eternal two-phase cycle.)

Thanks for your interest.

Michael

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I consider gravitational fields and electromagnetic fields operating across empty space as more reasonable than saying space is not actually empty but rather filled with some unknown medium/aether/whatever and calling it spacetime.

 

It seems you have a bit of a paradox on your hands. You want space to be empty. You want distance between two objects to be “no-thing-ness”. Yet, you acknowledge there must be something connecting all this mass in the universe—a gravitational field of sorts. But, it can’t be the field Einstein proposes, because it is something rather than nothingness. Yet, there needs to be something... But, there can't be something...

 

I believe the problem might be less with general relativity than the preconceptions you have about general relativity.

 

For example, you continually claim that Einstein's spacetime is some kind of malleable medium made of bendable stuff. I (and others) have corrected you on this multiple times, yet you continue criticizing GR on that basis.

 

Gravitation is a field which acts as per the universal law thereof, "directly with massiveness and inversely with distance"... Just like Newton said. He didn't like "action at a distance" either, but the equations still work

 

You might mean "proportional to mass and inversely proportional to the square of the distance".

 

The theory of gravity that Einstein proposed gives different answers from the law of gravity that Newton proposed. Where these differences have been tested, the results always agree with Einstein. For example, general relativity predicts light will be deflected by mass at twice the amount Newton's law of gravity predict.

 

In order to convince you of this, I will quote material speaking to the subject. I hope you consider it. I hope you read the entire link following the quote.

3.4.1 The deflection of light

 

A light ray (or photon) which passes the Sun at a distance d is deflected by an angle

[math]\delta \theta = \frac{1}{2}(1 + \gamma) \frac{4M_{\odot}}{d} \frac{1+cos\Phi}{2}[/math]

It is interesting to note that the classic derivations of the deflection of light that use only the corpuscular theory of light (Cavendish 1784, von Soldner 1803), or the principle of equivalence (Einstein 1911), yield only the “1/2” part of the coefficient in front of the expression in Equation). But the result of these calculations is the deflection of light relative to local straight lines, as established for example by rigid rods;
however, because of space curvature around the Sun, determined by the PPN parameter [math]\boldsymbol\gamma[/math], local straight lines are bent relative to asymptotic straight lines far from the Sun by just enough to yield the remaining factor “[math]\boldsymbol\gamma[/math]/2”.
The first factor “1/2” holds in any metric theory, the second “[math]\gamma[/math]/2” varies from theory to theory. Thus, calculations that purport to derive the full deflection using the equivalence principle alone are incorrect.

The prediction of the full bending of light by the Sun was one of the great successes of Einstein’s GR.

 

...the development of radio-interferometery, and later of very-long-baseline radio interferometry (VLBI), produced greatly improved determinations of the deflection of light. These techniques now have the capability of measuring angular separations and changes in angles to accuracies better than 100 microarcseconds.

 

In recent years, transcontinental and intercontinental VLBI observations of quasars and radio galaxies have been made primarily to monitor the Earth’s rotation (“VLBI” in Figure 5 ). These measurements are sensitive to the deflection of light over almost the entire celestial sphere (at 90°from the Sun, the deflection is still 4 milliarcseconds). A 2004 analysis of almost 2 million VLBI observations of 541 radio sources, made by 87 VLBI sites yielded [math]\mathbf{(1+ \boldsymbol\gamma )/2=0.99992 \pm 0.00023 }[/math], or equivalently, [math]\mathbf{ \boldsymbol\gamma - 1 = (-1.7\pm4.5) \times 10^{-4}}[/math]
.

 

[my bold]

 

 

You are simply incorrect. Every conceivable test of general relativity (as above) has sided against Newton. We have moved past the question of "is general relativity correct" and moved on to "why is general relativity correct". There are many, many questions yet to be answered, but you are moving backwards rather than forwards in claiming Newton's law of gravity is sufficient.

 

~modest

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I asked Modest several very specific questions (transcribed below) which he chose not to answer.

 

Your six questions involved the reification of spacetime, non-Euclidean space, parallel lines, emptiness, the "end of space", and reification again.

 

I addressed all of these (with the exception of the "end of space") at length in post #37 right after you asked them. But, I'm not trying to debate you. Many of your questions are based on misconceptions and bad assumptions regarding scientific theories that I think need responding to directly. In other words, I'm answering you the best I know how.

 

~modest

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The spacetime interval is a side effect of how we map space and time into a useful metric (Minkowski space). It’s useful because the spacetime interval is invariant—all observers agree on it regardless of their frame of reference. It’s easy to see that a null interval is invariant. It’s the same as saying all observers agree on the speed of light.

 

So, your question (philosophically) is probably equivalent to asking why the the speed of light is the same for everybody and maybe also having to do with the isotropy of spacetime.

I largely agree with what you have said, but I don't agree that the zero spacetime interval is comparable to the speed of light. The speed of light being the same in every frame of reference is an axiom of special and general relativity. It is assumed to be true, and the Lorentz transformation and the spacetime metrics follow directly from that assumption. The zero spacetime interval is a conclusion from the spacetime metrics.

 

Anyway, I don't see that any of this answers my question. In my understanding, the spactime interval is taken to be the "distance" in spacetime between two events. But a zero spacetime interval does not mean that the events happen at the same place (co-located), nor that they happen at the same time (simultaneous). So what does a zero spacetime interval mean?

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I am just trying (and failing) to make sense of "spacetime" as a bendable entity/medium or what I have been calling its reification into a malleable medium, since sceince documents consistently refer to it as curved, expanding, etc.

 

I have yet to see why a common sense Euclidean model of cosmos and parts thereof will not work without the invocation of (what appears to me to be) non-Euclidean nonsense as models of time, space, timespace and cosmology in general. With the above in mind, I asked Modest several very specific questions (transcribed below) which he chose not to answer.

How about you?

I answered as best I can when I said that the relationships in spacetime are non-linear, which is why an Euclidean model simply won't work as a model of it. As to your specific questions, I'll leave that for Modest to reply...

 

Finally, do you have any comment on my take on the present (now) being *now everywhere simultaneously*, ongoing always and not naturally segmented into "time units?"

This is a perspective transcending relativity and local perspectives and applicable to the the whole Bang/crunch cosmology, i.e., not about what who can see when... depending of course on lightspeed, the basis of relativity theory. It could be called a "thought experiment" from cosmic perspective... that "it" is now everywhere always, ongoing perpetually, eternally with no real beginnings or endings. (And it solves the problem of where "it all came from in the first place, there being no "first place" but an eternal two-phase cycle.)

I happen to believe in an unitary "now" that is universal. BUT that is not compatible with special and general relativity. Here we are discussing spacetime, so my beliefs are basically irrelevant.

 

Even so, an universal "now" is nothing to do with the universe being "ongoing always and not naturally segmented into time units". The concept of an universal "now" is compatible with presentism and eternalism (which is what you seem to be describing). Though, on second thoughts, even eternalism does not require the universe to be never ending. It's just a view that all of time (for however long the universe lasts) is "ontologically on a par".

 

So I'm not sure what meaning can be ascribed to the universe being "ongoing always and not naturally segmented into time units". It certainly has little to do with modern cosmology, because that starts a fraction of a second after the big bang and ends a fraction of a second before the big crunch (if that happens). What may have happened before the big bang, and after the big crunch are outside current cosmology. I happen to like the cyclical big bang/big crunch idea, but I don't really have any strong feelings about it as I can't see that it really answers any questions. I prefer to think of time as starting at the big bang and ending at the big crunch. Then the universe exists "for all of time" but without necessitating "all of time" to be infinite.

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I'm sorry, I don't understand what this means. How can space/mass and time "toggle out of existence alternatively"?

 

how does an object moves in space?

it must disappear in an instant from its original position and randomly reappear to its next position. in the newtonian world objects appears to move smoothly and continuously like a car cruising along the road. but motions imo are actually more like "neon lights". there is an illusion that lights is "running", but actually it turns on and off in sequence to give an appearance that the neon lights are moving.

 

if we have to believe einstein that space is not an absolute background where objects exists but only spatial relationships between objects and also the it is not empty but also radiates energy. .. then matter and space can be imagined to be made of the same substance and appear and disappear with objects at the same time. there is a progression instant by instant from the eternal moment of non-locality to spacetime locality the same way the pc monitor refresh 60 times per second to "update" changes that are taking place.

 

what is the frame of reference in order for spacetime to be coherent, consistent or stable. if there is to be an absolute frame of reference, logically it must be outside the world of relativity. iow, outside spacetime. what is the ultimate constituent of spacetime if it is coming out from non-locality? it is by and large a process of emergence. a process is an action. the basic unit of the universe is an act.

 

so what is an act?

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.. then matter and space can be imagined to be made of the same substance and appear and disappear with objects at the same time. there is a progression instant by instant from the eternal moment of non-locality to spacetime locality.... ...it is by and large a process of emergence. a process is an action. the basic unit of the universe is an act.

 

This sounds similar to Whitehead's Metaphysics, and Process Philosophy.

Whitehead's Metaphysics

...and

Alfred North Whitehead (Stanford Encyclopedia of Philosophy)

http://en.wikipedia.org/wiki/Alfred_North_Whitehead

Concomitantly, Whitehead developed a keen interest in physics: his fellowship dissertation examined James Clerk Maxwell's views on electricity and magnetism. His outlook on mathematics and physics were more philosophical than purely scientific; he was more concerned about their scope and nature, rather than about particular tenets and paradigms.

....

The period between 1910 and 1924 was mostly spent at University College London and Imperial College London, where he taught and wrote on physics, the philosophy of science, and the theory and practice of education. He was a Fellow of the Royal Society since 1903 and was elected to the British Academy in 1931. In physics, Whitehead articulated a rival doctrine to Einstein's general relativity. His theory of gravitation is now discredited because its predicted variability of the gravitational constant G disagrees with experimental findings.[1]. A more lasting work was his Enquiry Concerning the Principles of Natural Knowledge (1919), a pioneering attempt to synthesize the philosophical underpinnings of physics. It has little influenced the course of modern physics, however.

... Process Philosophy

The genesis of Whitehead's process philosophy may be attributed to his having witnessed the shocking collapse of Newtonian physics, due mainly to Einstein's work. His metaphysical views emerged in his 1920 The Concept of Nature and expanded in his 1925 Science and the Modern World, also an important study in the history of ideas, and the role of science and mathematics in the rise of Western civilization. Indebted as he was to Henri Bergson's philosophy of change, Whitehead was also a Platonist who "saw the definite character of events as due to the "ingression" of timeless entities"[3]. -wiki

Whitehead's Metaphysics of Creativity [978-0-7914-0203-0] - $21.95 : flux: The Process-Relational Bookstore

 

... as well as the "creativity" theories of Stuart Kauffman.

Perspectives: Why humanity needs a God of creativity - science-in-society - 07 May 2008 - New Scientist

...and

Stuart Kauffman | Institute for Biocomplexity and Informatics (IBI)

 

Yes, seeing particles as simply a higher density "whirlpool," or some unique conformation of highly "wrapped-up" spacetime, is a helpful way to look at this stuff.

 

...those 'fractal wakes' would be a way of visualizing the sharp drop-off in "density" as we move away from the point-source of a whirlpool, conformation, disturbance, etc....

 

...I feel a disturbance in the....

 

~ :doh:

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Yes, seeing particles as simply a higher density "whirlpool," or some unique conformation of highly "wrapped-up" spacetime, is a helpful way to look at this stuff.

 

...those 'fractal wakes' would be a way of visualizing the sharp drop-off in "density" as we move away from the point-source of a whirlpool, conformation, disturbance, etc....

 

...I feel a disturbance in the....

 

~ :doh:

 

i'm not familiar with whitehead, but i do have a little readings of arthur young's theory process. perhaps the later theory is much contemporary with a better understanding of quantum physics.

 

perhaps fractal geometry can explain how things shape up. but the question still remains ... what is it that takes shape. what vibrates or what causes motion?

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i'm not familiar with Whitehead, but i do have a little readings of Arthur Young's theory process. perhaps the later theory is much contemporary with a better understanding of quantum physics.

 

perhaps fractal geometry can explain how things shape up. but the question still remains ... what is it that takes shape. what vibrates or what causes motion?

 

Yes, I carefully avoided your question of "what is an act?" :doh:

 

I assume it is the interaction of the so-called "higher" dimensions with each other, which then generates what we perceive as paticles/energy.

 

In my view those "higher" dimensions are the basics of existence, the truely lowest dimensions (without spacetime); and their conformation determines the placement of matter/energy in a new, emergent dimension (ours); which then generates spacetime as described previously.

 

"Basics" = FSM (spaghetti ball) = lower dimensions, or basic dimensions:

The basics interact and ...emerge as the artifact of 4D spacetime (a "true, higher" dimension).

 

The Eight Basic Dimensions (FSM):

 

Time/Stasis

Harmony/Dischord

Empathy/Apathy

Intention/Inertia

Synergy/Entropy

...???

 

...or any of the basic elements from Eastern or Western philosophies...

...(as a way of avoiding the spatial orientation of "dimensional" thinking)...

...but I suspect that if you pick the right eight, then you get a nicely integrated spiritual and material worldview.

=== :doh:

 

p.s.

...but I do see, maybe(?), time as the connection back from spacetime to the basic eight dimensions,

constraining how the eight can change (once they generated spacetime initially).

~~

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