What is "spacetime" really?

[Pyrotex]

Seems to me that Michael denies the ontological existence of Space (and Time) just because of their attributes.

Space can't be "seen" -- it's transparent.

Well, so is pure glass that has been highly polished.

Space can't be "felt" -- it's immaterial.

Well, so is air on a clear, still day.

Space can't be interacted with chemically.

Well, neither can Helium.

Space doesn't have any boundaries.

Well, neither does the surface of a sphere.

Space just "contains" Nothing.

Well, you have Nothing to be thankful for.

;)

[Michael Mooney]

Freeztar:

Time seems much more tenuous than space from a philosophical standpoint, imho.

....

FWIW, that thread did not really harp on the ontology of time too much (iirc), so it would be great to bring some of the ideas expressed there into this thread. Hopefully we can accomplish this without requiring the actual physics of relativity and common scientific theory regarding time.

 

Transcribed from my "time piece";) in the "What is Time" thread:

Two answers to consider simultaneously...

One:

It is the *concept/measure* of event duration, like

A: one rotation of earth (day and standardized divisions thereof... hours, minutes, seconds... nanoseconds)

B: one earth orbit around sun (measured three different ways giving three technically different *spans of time*)

C: the great cycle of the precession of the equinox

D: a complete "bang/crunch" cycle, if my favorite comology is true...

...You get the idea.

Two: Now, the present is always present, not sliced into units of time in the real world/cosmos. As I've said many times, future is not yet real and present and past is not still real and present, and there is no "time" between future and past. Therefore "time" is not a natural reality in the strict ontological sense of what is real.

So, "spans of time", as above are as real as we make them. There is no cosmic counter clicking at every complete earth rotation, year, etc. Yet we can "be on time" to work by common consensus on the convention, time. and we can plug in "time" as a component of velocity and calculate and execute a round trip to the moon.

 

It is also conventional to call "time" the fourth dimension added to the obvious spacial three which describe volume. Then we can avoid having two airplanes at the same coordinates in air-space at the same time. A very useful convention.

But it doesn't expand and contract as an actual entity of any kind... See Two above.

 

So, as a "component of spacetime" what is it that we are actually talking about?

 

Michael

[Michael Mooney]

Freezetar:

Are you suggesting something like a cyclic universe theory?

 

Yes. A modified version of the old "Bang/Crunch" One of the major criticisms leveled against the "bang/crunch" cosmology was the "missing matter" argument... That not enough matter has been found to reach the critical cosmic density required for the gravitational net to reverse the outward expansion and commense the implosion half of the two-phase cycle. But mush more matter is now being detected now (for instance, by NASA's Chandra Observatory)... and various types of "mystery matter" as well as more simply not emiting or reflecting light.)

Another criticism was the entropy argument... losing energy and running down. But nothing is ultimately "lost in space." Matter/energy is neither created nor destroyed but just changes form... and in this model, it all comes back for another bang... again and again.

Another criticism is that all matter coming back at once could not be "launched" again by known dynamics... that the crushing force of gravity could not be overcome by fusion at the core. But a scaled down version, with many incoming phases and smaller balls of matter "crunching"... more like greatly scaled-up supernovae explosions... could make my "multiple bangs and crunches" (The Great Cosmic Juggling Act ) cosmology work.

 

But, if one can imagine infinite nothingness, then it can be used to contrast what we consider the ontological reality of all "things

 

Here again there is no possible "end of space" regardless of what it may contain beyond our cosmic event horizon. Yet the ontology of space I am most focused on here is simply that which is between "things" on all scales... and that can be any designated "volume" which will have some "things" in it but mostly empty space between... whether within atoms, between them, or between celestial bodies/ masses.

 

His (Einstein's) revelations are incredibly useful to us in a practical manner. This is where the disconnect between physics and philosophy is apparent, as you've pointed out many times.

Yes. The math of relativity certainly predicts the effects of gravity as effecting the *trajectories of actual objects through space* way better than a strictly Newtonian paradigm. It's just that he went off the deep end ontologically by reifying "spacetime" as a medium with all those "properties" which Pyrotex and I just debated.

 

So space, in this case, is full of repulsive and attractive forces and hence is not really a void. The space is not empty, yet, it's also not a thing (hence I used the container analogy before).

Agreed. Gravity and electromagnetic waves obviously travel through space. I am not saying it is a void in that regard. Just not a medium "itself" with such properties as curvature, shape, expandability/contractability, "time dilation" etc. Big difference!

 

CMBR is a common acronym in physics that stands for Cosmic Microwave Background Radiation.

Thanks for the reminder. I was "all over" the results of the COBE satellite and the later pictures and mapping of background radiation from the Bang.

However, the theory that "space itself" expands... and did so way faster than lightspeed soon after the "beginning of time" ;) (inflationary cosmology) is based on the erroneous ontology of space and time reification, as I been harping on here for over 50 pages.

 

I just posted my take on "time" again above. Eager for yours.

Michael

[Pyrotex]

I think it all boils down to "dimensions of freedom".

In other words, any object or particle can be "located" somewhere in space.

If you want a specific "event", say the location and time the particle emitted a photon,

then you can "locate" the event in space and time.

You need four parameters to do this.

"Spacetime" becomes shorthand for the set of all possible space-time event locations.

 

I disagree that Space is Nothingness. I deny that you can even define "nothingness" in any meaningful way that still allows it to be "observed" and have non-zero volume.

 

Here's something to ponder. We do not argue that the air is "nothingness" or that it has no ontological existence. We have organic senses with which to "feel" air as it moves or we move through it.

 

Perhaps this argument about Space and its ontological existence would evaporate just as quickly if we had the appropriate senses.

[Michael Mooney]

Erasmus:

Lets instead talk about curved three dimensional space-

 

If space is truly the emptiness between "things" then there is nothing to "curve."

Obviously spheres and such have *curved surfaces.* These are geometric forms, and many are actually bodies in the real cosmos. I though your original exercise with the triangle drawn on the driveway... having over 180 degrees... was an illustration of a very small slice of earth's surface, which of course has curvature, and I agreed it would have more than 180 degrees because the arcs were not actually straight lines. Then I scaled it up to emphasize the curvature on a "triangular" slice of earth, pole to equator. Then you scaled up to the lines between three galaxies. This exercise was ostensibly to show that the "space itself" between the galaxies has curvature. Ooopse! Back to square one... Space is not a "thing." "It" is not an "it." The (relative) emptiness between the three galaxies has no curvature. If "Kosmos";) drew three straight lines between the three galaxies, the angles would total 180 degrees, just like a little one "on paper"... a flat surface on earth. The plane your three straight lines between galaxies will create is a very large flat plane, not a big curved taco chip.

That's how I "see" it.

I know you disagree. I don't know where to go with the triangle exercise from here.

 

Michael

[Michael Mooney]

Seems to me that Michael denies the ontological existence of Space (and Time) just because of their attributes.

Space can't be "seen" -- it's transparent.

Well, so is pure glass that has been highly polished.

Space can't be "felt" -- it's immaterial.

Well, so is air on a clear, still day.

Space can't be interacted with chemically.

Well, neither can Helium.

Space doesn't have any boundaries.

Well, neither does the surface of a sphere.

Space just "contains" Nothing.

Well, you have Nothing to be thankful for.

;)

Maybe space can't be seen 'cuz there is nothing to see in empty space. I'm sure we can see the molucules of the glass under an electon microscope.

 

If space is the absence of "things", it's a lot different than air, which is a variety of actual gases.

Chemistry requires actual molecules of stuff interacting. An empty test tube contains no chemisty... but can be filled with helium.

 

The surface of a sphere is its boundary. Space has no surface.

 

The nothingness between things is empty space.

Thanks for nothing.:hihi:

 

Btw, maybe we can do some serious ontology if you are willing to back up and answer my reply to your:

 

Yes, if I understand the word correctly, we physicists do "reify" space-time, giving it an independent existence, like any other "thing" or "object", such as a photon, an elm tree, the house next door, and the woman who lives in the house."

 

... as follows:

 

Well, therein lies the confusion, "right off the bat." I challenge the assumption that spacetime is a "thing" from the git-go, hence, "reification." Obviously there is a difference between the word for( and concept of) "a photon, an elm tree, the house next door, and the woman who lives in the house... and the actual photon, elm tree, etc. Ontologically, there are actual photons, etc.... which the words simply denote. I contend that there is no parallel ontology for the actual existence of "spacetime" as also a "thing in the real world." The objects you mention do have actual independent existence, whereas "spacetime does not.

 

OK?

Michael

[Michael Mooney]

Pyrotex:

I think it all boils down to "dimensions of freedom".

In other words, any object or particle can be "located" somewhere in space.

If you want a specific "event", say the location and time the particle emitted a photon,

then you can "locate" the event in space and time.

You need four parameters to do this.

"Spacetime" becomes shorthand for the set of all possible space-time event locations.

This is what I've been saying through this whole thread.... that space has three dimensions, and "time" is when an event happens.

 

So then.... what "curves", etc., etc, in this common sense explanation of three dimensional space as locating stuff and "time frame" as simply the "when?"

 

I disagree that Space is Nothingness. I deny that you can even define "nothingness" in any meaningful way that still allows it to be "observed" and have non-zero volume.

 

If there were no space between "things", the universe would be "solid stuff", not just matter, 'cuz matter has lots of empty space in it. The space between the "things" is lack of such things, or no-thing-ness.

What is your problem with this?

Michael

[freeztar]

Yes. A modified version of the old "Bang/Crunch" One of the major criticisms leveled against the "bang/crunch" cosmology was the "missing matter" argument... That not enough matter has been found to reach the critical cosmic density required for the gravitational net to reverse the outward expansion and commense the implosion half of the two-phase cycle. But mush more matter is now being detected now (for instance, by NASA's Chandra Observatory)... and various types of "mystery matter" as well as more simply not emiting or reflecting light.)

Another criticism was the entropy argument... losing energy and running down. But nothing is ultimately "lost in space." Matter/energy is neither created nor destroyed but just changes form... and in this model, it all comes back for another bang... again and again.

Another criticism is that all matter coming back at once could not be "launched" again by known dynamics... that the crushing force of gravity could not be overcome by fusion at the core. But a scaled down version, with many incoming phases and smaller balls of matter "crunching"... more like greatly scaled-up supernovae explosions... could make my "multiple bangs and crunches" (The Great Cosmic Juggling Act ) cosmology work.

 

Well, I'd rather not get into this discussion here (though a new thread on this might be appropriate) but suffice it to say that there are valid objections to the cyclic universe theory. Mind you, I think it is certainly the coolest option for the universe to take. :hihi:

 

Here again there is no possible "end of space" regardless of what it may contain beyond our cosmic event horizon.

 

I'm not so sure about that. How can you be so sure?

I know it makes sense to consider any "void beyond" the same way we typically think about space, but I'm suggesting we don't think of it as space. The closest analogy I can come up with is imagining a one-dimensional space. It's certainly counter-intuitive in many ways, but it's a great mental exercise imho, especially for this topic.

 

Yet the ontology of space I am most focused on here is simply that which is between "things" on all scales... and that can be any designated "volume" which will have some "things" in it but mostly empty space between... whether within atoms, between them, or between celestial bodies/ masses.

Yes, I understand.

 

The math of relativity certainly predicts the effects of gravity as effecting the *trajectories of actual objects through space* way better than a strictly Newtonian paradigm. It's just that he went off the deep end ontologically by reifying "spacetime" as a medium with all those "properties" which Pyrotex and I just debated.

I don't know that I'd say "off the deep end".

I do understand your problem with the reification of spacetime.

 

Agreed. Gravity and electromagnetic waves obviously travel through space. I am not saying it is a void in that regard. Just not a medium "itself" with such properties as curvature, shape, expandability/contractability, "time dilation" etc. Big difference!

Indeed, but then we must ask...so what does cause the apparent effects of curvature, time dilation, etc.?

 

Thanks for the reminder. I was "all over" the results of the COBE satellite and the later pictures and mapping of background radiation from the Bang.

However, the theory that "space itself" expands... and did so way faster than lightspeed soon after the "beginning of time" :hihi: (inflationary cosmology) is based on the erroneous ontology of space and time reification, as I been harping on here for over 50 pages.

Well, I must be missing something. Why is inflationary cosmology at odds with your cyclic cosmology? A cyclic cosmology still needs an inflationary (and deflationary) period, correct?

 

But of course, to assume an inflating universe, we must attribute at least one property to space, that it can expand (and possibly contract). The other option is that the universe doesn't expand or contract. Space just is and has always been. But data we've collected on the CMBR tells us that this theory is not possible. ;)

 

I just posted my take on "time" again above. Eager for yours.

Michael

 

Ok, I'll post over there initially. I need to reread the thread so it might 'be awhile'. :lol:

[Michael Mooney]

Freezetar:

Well, I'd rather not get into this discussion here (though a new thread on this might be appropriate) but suffice it to say that there are valid objections to the cyclic universe theory.

Agreed, it was an aside, but I just offered the three primary objections to the old "Bang/Crunch" and showed how I see them as not valid.... at least not as precluding the posibility of the cosmology.

Me:

Here again there is no possible "end of space" regardless of what it may contain beyond our cosmic event horizon.

You:

I'm not so sure about that. How can you be so sure?

I know it makes sense to consider any "void beyond" the same way we typically think about space, but I'm suggesting we don't think of it as space. The closest analogy I can come up with is imagining a one-dimensional space. It's certainly counter-intuitive in many ways, but it's a great mental exercise imho, especially for this topic.

 

I can be sure because any boundary one posits as "an end of space" will be an arbitrary mental construct, and still one can ask, "What then is on the outside of this supposed boundary? The only and obvious answer is, "more space... infinite space."

Seems I still don't know what you mean by space. I mean the empty volume between the things that do occupy space. In the case of infinite space it is volume with no defined boundary... which will just have more space beyond the boundary.

"One-dimension" is the line or distance designation of the 3 spacial dimensions, no?

Me:

Agreed. Gravity and electromagnetic waves obviously travel through space. I am not saying it is a void in that regard. Just not a medium "itself" with such properties as curvature, shape, expandability/contractability, "time dilation" etc. Big difference!

You:

Indeed, but then we must ask...so what does cause the apparent effects of curvature, time dilation, etc.?

 

Seems to me that gravity attracting masses and light is the cause of their curved trajectories, so there is no need to "make something out of nothing" (space) and attribute curvature to "it."

I know that clocks slow down under well known conditions... that even atomic clocks slow down as the rate of decay of their atoms slows down. Given what I've said about time , transcribed above, I obviously don't believe that time is "itself" an event "happening" which can slow down or "dilate" to create "more time" for a specific event that it's natural "elapsed time" we call its "duration"... between clicks of the stopwatch, so to speak.

 

You:

Well, I must be missing something. Why is inflationary cosmology at odds with your cyclic cosmology? A cyclic cosmology still needs an inflationary (and deflationary) period, correct?

 

As I understand inflationary cosmology, it posits that "space itself expands." No go if space is is emptiness, etc. My cosmology sees the actual stuff, of cosmos exploding out from a ball of cosmic stuff (a series of them actually) which have come back from their outward explosion/expansion. This is "real stuff" expanding out into empty space and contracting back after reversing its outward expansion.

You:

 

But of course, to assume an inflating universe, we must attribute at least one property to space, that it can expand (and possibly contract). The other option is that the universe doesn't expand or contract. Space just is and has always been. But data we've collected on the CMBR tells us that this theory is not possible.

 

As above. Big difference between real stuff (matter/energy/plasma) exploding/expanding outward into space and "space itself" exploding/expanding. (But I'm repeating myself.)

 

So, anyway, I'll be looking forward to your take on what "time" is.

Michael

[watcher]

The nothingness between things is empty space.

 

empty space turned out to be not empty at all.

there is always a minimum amount of energy present in a vacuum.

[Erasmus00]

If "Kosmos";) drew three straight lines between the three galaxies, the angles would total 180 degrees, just like a little one "on paper"... a flat surface on earth.

 

In this statement you disagree with predictions of general relativity. GR unambiguously predicts that such a triangle WILL not have 180 degrees. This is an empirical prediction. You aren't just disagreeing with reification here, but actual predictions

 

This is what I've been trying to get at- your ontology contradicts predictions made by GR. You are welcome to do this, but you should realize you are.

[jedaisoul]

I can be sure because any boundary one posits as "an end of space" will be an arbitrary mental construct, and still one can ask, "What then is on the outside of this supposed boundary? The only and obvious answer is, "more space... infinite space."

If space is nothing, then I accept that it could be boundless. However, there cannot be more of it. You can't have more nothing! And to be infinite, something has to exist. "Nothing" cannot be infinite.

 

So it seems that, no only are you contradicting GR (as mentioned in Erasmus00's post), you are also reifying space. Now that may simply be because you are using the terms "more" and "infinite" loosely, but if you make claims like this, you must expect them to be picked up on.

[Michael Mooney]

Seems to me that I've answered the questions/criticisms of the last three posts (by Watcher, Erasmus, and Jedaisoul) many times already in this thread.

Must be close to "breaktime"... or time to leave.

Just on this page alone, I think I've replied*, to the best of my ability, to all of the objections raised on this page, including the last three posts.

 

Here is is a review of those replies*:

 

A: If space is truly the emptiness between "things" then there is nothing to "curve."

 

B: If there were no space between "things", the universe would be "solid stuff", not just matter, 'cuz matter has lots of empty space in it. The space between the "things" is lack of such things, or no-thing-ness.

 

C: Yet the ontology of space I am most focused on here is simply that which is between "things" on all scales... and that can be any designated "volume" which will have some "things" in it but mostly empty space between... whether within atoms, between them, or between celestial bodies/ masses.

 

D: Agreed. Gravity and electromagnetic waves obviously travel through space. I am not saying it is a void in that regard. Just not a medium "itself" with such properties as curvature, shape, expandability/contractability, "time dilation" etc. Big difference!

 

E: I mean the empty volume between the things that do occupy space. In the case of infinite space it is volume with no defined boundary... which will just have more space beyond the boundary.

 

F:Seems to me that gravity attracting masses and light is the cause of their curved trajectories, so there is no need to "make something out of nothing" (space) and attribute curvature to "it."

 

So... One at a time...

Jediasoul:

]If space is nothing, then I accept that it could be boundless. However, there cannot be more of it. You can't have more nothing! And to be infinite, something has to exist. "Nothing" cannot be infinite.

So it seems that, no only are you contradicting GR (as mentioned in Erasmus00's post), you are also reifying space. Now that may simply be because you are using the terms "more" and "infinite" loosely, but if you make claims like this, you must expect them to be picked up on.

 

How is it that you believe that nothingness, emptiness can not be infinite? What do you propose as its finite boundary, and what's on the other side?

 

" And to be infinite, something has to exist." (??)

This defies the meaning of "infinite" as without end or boundary. All "things" are defined by their boundries.

Reification is making something out of nothing in our own minds... like "spacetime" into a medium with various attributes.

--------------

 

Erasmus:

Replying to my:

If "Kosmos" drew three straight lines between the three galaxies, the angles would total 180 degrees, just like a little one "on paper"... a flat surface on earth.

 

In this statement you disagree with predictions of general relativity. GR unambiguously predicts that such a triangle WILL not have 180 degrees. This is an empirical prediction. You aren't just disagreeing with reification here, but actual predictions

 

This is what I've been trying to get at- your ontology contradicts predictions made by GR. You are welcome to do this, but you should realize you are.

 

One of the two aspects of relativity with which I disagree (contradicting GR) is that "space has curvature." Is it not true that this is the tenant upon which the triangle with over 180 degrees is based? I know that a 3-d curved triangular slice of a curved surface has over 180 degrees.

This in turn falls back on the first departure from Euclidean space in asserting that the shortest distance between two points is no longer a straight line but rather the path of light from source to destination... which is curved by the pull of gravity of the masses it passes.

A triangle on a flat plane still has 180 degrees.

-------------------

 

To my:

"The nothingness between things is empty space."...

Watcher wrote:

empty space turned out to be not empty at all.

there is always a minimum amount of energy present in a vacuum.

 

See review of my statements above. It would be absurd to deny the existence of all things and say "all space is empty." I've repeated ad naseum that objects exist and move *through space.*

Space is emptiness.... the absence of things between things.

I just can not say it any more clearly.

 

Thanks, everyone. Intending to take that break from the site for awhile now.

 

Michael

[Erasmus00]

One of the two aspects of relativity with which I disagree (contradicting GR) is that "space has curvature." Is it not true that this is the tenant upon which the triangle with over 180 degrees is based? I know that a 3-d curved triangular slice of a curved surface has over 180 degrees.

 

By throwing this out (i.e. insisting the triangle has 180 degrees), you throw out nearly all of general relativity. The triangles with other than 180 degrees are central to the theory, and required to get other predictions right.

 

You are of course, welcome to do this. But you need to realize your ontology has real, physical consequences.

[watcher]

See review of my statements above. It would be absurd to deny the existence of all things and say "all space is empty." I've repeated ad naseum that objects exist and move *through space.*

Space is emptiness.... the absence of things between things.

I just can not say it any more clearly.

 

residual energy in empty space or in physical system in general is not an object. energy is not a thing. you reify energy when you equate that the energy that can't be removed in an empty space is a thing.

 

ontologically, it's more likely that there is no such thing as space at all, only energy, or at least in cosmogenesis, energy is more fundamental than space.

[Michael Mooney]

By throwing this out (i.e. insisting the triangle has 180 degrees), you throw out nearly all of general relativity. The triangles with other than 180 degrees are central to the theory, and required to get other predictions right.

 

You are of course, welcome to do this. But you need to realize your ontology has real, physical consequences.

 

OK, intended a break, but "looked back" and saw the misunderstanding more clearly.

Hopefully this will resolve it.

I am very glad that my ontology has real physical consequences. One will be that the path of light no longer defines "a straight line through space" (as gravity obviously bends it into a curved path.)

 

Of course "curved space" is "central to relativity." I'm saying that the math does not need the "bogus model" or "metric" of "curved space" to *work!* The math and all calculations can work on the *model* of curved space... for telemetry, etc., without reifiying *the emptiness between things in space* into "curved spacetime."

 

Maybe my most cogent argument here is based on my 40 years of transcending both personal identity/perspective and the scientific equivalent of religion, TIDE (about half tongue-in-cheek)... Thoroughly Indoctrinated Disciples of Einstein.

 

Straight lines are actually straight... Not curved, just because that is what light does as it travels throiugh space.

"Triangles" are actually three sided shapes on flat planes with straight lines connecting three points. The have 180 degrees as the tolal of their angles.

 

Now... you can create any three sided, three dimensional slice of a curved surface you want and it will total more than 180 degrees of angles. What have you proved? You have redefined the straight line and the triangle in service to relativity.That the path of light is now the definition of a straight line, tho its path is curved by gravity. BOGUS.

 

Space is not a thing. "It" is lack of "it-ness." Emptiness. No attributes. No curvature.

 

Again ... the math does not require the BOGUS metric of curved space.

 

Gotta go now. Its Sat night an my wife is ready to go out and dance!

 

Goodnight.

Michael

[Erasmus00]

Of course "curved space" is "central to relativity." I'm saying that the math does not need the "bogus model" or "metric" of "curved space" to *work!* The math and all calculations can work on the *model* of curved space... for telemetry, etc., without reifiying *the emptiness between things in space* into "curved spacetime."

 

There is a disconnect- the whole of GR is contained in one equation, an equation that says that the curvature of space (the metric) (i.e. how different the angles of a triangle are from 180 degrees) is proportional to the amount of energy in the space. There is no mathematics of GR without a metric, no model without our triangles that don't have 180 degrees.

 

From knowing how local triangles differ from 180 degrees, we can work out all the observational consequences of GR, but make no mistake, it is strictly based on this idea that triangles can have other than 180 degrees. Your ontology strictly disallows this, and so it strictly disallows GR.

 

Maybe my most cogent argument here is based on my 40 years of transcending both personal identity/perspective...

 

The problem with using meditation/visions as a basis for physics is that two people meditating can experience and report on very different things. Whose vision gets priority?

 

"Triangles" are actually three sided shapes on flat planes with straight lines connecting three points. The have 180 degrees as the tolal of their angles.

 

But why? Can you prove it?

 

That the path of light is now the definition of a straight line, tho its path is curved by gravity. BOGUS.

 

I'm not suggesting redefining a straight line using a light path, I'm saying take a straight edge, or however, and draw the absolute straightest lines you can. You still won't get 180 degrees.

 

Again ... the math does not require the BOGUS metric of curved space.

 

Actually, yes, it does.