What is "spacetime" really?

[Michael Mooney]

Hi AnssiH,

My reply to Modest, just posted may answer most of your points here as well, but, I'll have a go anyway.

 

A:I have to say I am quite puzzled by your reply. Decided to give it one go anyway

M: I'm interested in what puzzeled you.

 

Sorry if I'm restating something that's already been beaten to death, I admit I have not read through the whole thread.

 

M: No prob. I haven't read the "What is time" thread either , but threw in my $.02 anyway... near the end, if you are interested in my ontology of time per se.

 

Quote:

Originally Posted by Michael Mooney View Post

I think we all understand 3D space and the concept of time as the motion or "duration of event" factor in the cosmos... i.e., dynamic, not static.

 

A point is a locus. (no dimension) A line is a distance, one dimensional. A plane is an area, two dimensional. A volume is three dimensional space. It can either have a shape or be infinite space with no boundary in any direction (no "end of space.)

 

This clearly describes the real world/cosmos.

 

A: Yes we all understand 3 dimensional euclidean spaces easily. And yes, that form clearly describes reality in very useful way as we all succesfully use that interpretation every day.

 

But here's my first point of confusion; I don't know if you are jumping to conclude that us being so fluent in understanding reality in this form also means reality is ontologically a 3D euclidean space?

 

M: I mean that if "space" is other than 3D (aside from "time" for the moment...)then then it is up to theorists of curved space (and dilated time, if we include that parameter) to explain *what it is in the real world.*

 

A:I mean, surely you can also say that relativistic spacetime describes reality (and I mean that without implying any ontology to "spacetime" itself). But the point you seem to focus on is "what is the form we are intuitively fluent with"? That by itself leads to some interesting epistemological questions, but I'd advice you to not jump into any ontological conclusions.

 

M:I don't agree that "relativistic spacetime" describes anything which can be known about the real world, as it is a fabrication based on the premise that gravity can not act through empty space without the medium ("fabric") "spacetime."

 

A: While we intuitively and fluently see reality as 3 dimensional euclidean space, there must exist a great number of definitions (one way or another) in order for us to interpret patterns in form of objects that move in such a way that we can say they operate inside an euclidean space.

 

M: What does "curved space" add to what we can directly observe about the curved trajectories of objects and light through space? And what does a supposed "4th spacial dimension" add to our understanding of the cosmos as it obviously exists in 3D space? "Another dimension at a right angle to volume?"

Applying Occam's Razor, the answer is, "nothing."

 

How did we get a fourth "axis" as a spacial "metric?" Does making sense count in your sense of ontology, or is internal consistency of the "theoretical metric" enough without a "real world" referent?

 

You continue:

A: "We also intuitively and fluently interpret some patterns as sounds and language, but that doesn't mean that ontologically there exists sounds and language. It's just, whatever it is that we interpret as sounds... ...or whatever we interpret as objects in space."

 

M: Woah! "Sound" is the word for actual waves in the air caused by compressive forces... It is ontologically real, "whether anyone hears a given remote sound or not. (See "tree falling in forest" argument above.)

 

A: This all reminds me of:

Definitions on space

M:

Not yet read.

 

A: I think you've said "space is what is empty" a few times here, and I would advice you to weight your thoughts really carefully right there as well, as you need fairly carefully define what you mean by empty. (And that will lead to all the questions of how space, and "straight lines" through space are measured and what is the associated naive realistic idea in our head)

 

M: Between "things" is the lack of things, space. If there were no space between things, the cosmos would be a solid block of fantasy matter, because even matter has space within and between atoms, and same for the macrocosm of all objects *in space.* And space, btw, *must be infinite*, as no case for an "end of space" can possibly be made.

 

So, as I told Modest, the case for space being "something" other than the obvious emptiness between things (on all levels) must be made, by "spacetime" theorists. The fact that trajectories of objects through space are curved does not make such a case.

 

Quote:

M: How then is the leap made to four spacial dimensions?

How is it that in non-Euclidean "space" a straight line is no longer the shortest distance between two points? Drawing it on a spherical surface is cool, but then the shortest distance (in the "real world") is through the sphere... like the needle I put through the arched paper in that argument awhile back. (Not refuted... no reply.)

 

Then on to parallel lines... which converge/diverge in non-Euclidean "space." How is that "really?"

 

Then there is the "hypercube" which, in the link (by Watcher) above was illustrated as merely an enlargement of the original cube. This does not establish a "real fourth spacial dimension."

 

Same with all the different "shapes of space"... spherical, parabolic saddle or inverted saddle... torus, etc. What is it exactly in the "real cosmos" that has shape?" It is the "stuff" *in space* in all of its various forms, or taken as a whole as "the cosmos" expanding out *into space.*

 

A:

"I'm assuming you know the "straight line no longer being the shortest distance" etc, these are simply the logical consequences springing from whatever exact definitions have been given for whatever space is under discussion."

M:

Definitions do not create extant realities, the subject of ontology. They only define a "metric" which may or may not have any referent at all in the real world.

 

A: I'm guessing the point you are trying to make here is simply that no one is able to visualize or intuitively understand 4 spatial dimensions and/or non-euclidean spaces in their head. That is of course true. What is there to conclude from that fact?"

 

M: Unless a "4th dimension" denotes a referent in "the real world" it remains fantasy physics... just like string/M-theory with its multiple manifold "imaginary universes/dimensions." (Now somewhere between 11 and 26 "dimendions"... or is it higher by now?)

 

Quote (M):

These are the ontological challenges I present in this thread.

And, "Oh, it's just a theoretical matrix" does not answer the ontological challenge.

 

A:

"I'm not sure what else you would want to hear. I think "it's just a theoretical matrix" means; "it's not an ontological construct, it's an epistemological construct, inside our head."

 

M: Yes, and that's where "spacetime" remains in "mainstream science" today.

 

A: We can imagine all kinds of constructs in our head, and the only ontological challenge involved there would be when a "theoretical matrix" yields valid predictions of reality. Whatever the essential relationships of that theoretical matrix are, they can be expressed in many different sorts of spaces and forms. In the case of relativistic spacetime, the logical (epistemological) reasons of it being valid can certainly be investigated, without knowing anything about the real ontological form of what we are investigating.

 

M: Internal consistency of theoretical metrics or matrices is not sufficient if it uses terms which remain simply imaginary, i.e., without observable referents.

 

Even "E=MC squared" must quantify amount and kind of actual mass and then give the energy yield in meaningful terms in the real world as well. So, so many grams of hydrogen yield so much energy in terms of "megaton equivalents of TNT" or whatever.

 

Yes, AnssiH, there *is* a real world beyond our theoretical descriptions of it! :)

 

A: I guess you should be interested of the epistemological question; why is 3 dimensional euclidean space so intuitive for us? I think there was some interesting commentary about that issue at:

http://hypography.com/forums/philosophy-of-science/philoso...mensional.html

 

M: Have yet to peruse that.

 

A: I have to say it was really hard to try and figure out what you meant to say really, so my apologies if I'm reading you completely wrong.

 

I am open to specific questions for clarification of what I mean in any and all cases.

Thanks for your interest.

 

Michael

[Michael Mooney]

Modest:

]Michael, you're just arguing for the purpose of arguing now. I won't engage you because there's no utility in it. You're also being quite rude. Why would you consider telling me I don't know what ontology is when I'm the person who told you 6 months ago that your question and your argument was one of ontology? You got mad at me then for telling you the OP was a matter of ontology and now you're saying I don't understand that the OP is a matter of ontology. Think about that... you're just waving your hands and yelling for the purpose of waving your hands and yelling. I'm not interested.

 

As you continue your discussion with others in the thread please keep these site rules in mind:

 

For the record, in response to Modest's last post, I am challenging the ontology of "spacetime." My every sentence is based on that challenge... well, most of them anyway.:)

I do not waste my time with such "trivial pursuits" as 'just for the sake of argument.'

(Yet another misconception.)

Also I have sincerely resolved to quit being rude. Avoiding rudeness is low priority in the philosophy of "radical honesty," but I have consciously made that concession in favor of respectful dialogue in pursuit of what is True (or not) about "spacetime." I will, in the future try to be even more respectful in this regard.

 

I have already admitted my mistake and your correct perspective on putting this thread in the "Philosophy of Science" forum, as it is focused on the ontology of spacetime. Yet my misgivings turned out to be valid. All scientists here so far have continued to assume that the ontological question is irrelevant, as the epistemology is assumed to vindicate all aspects of relativity including its reification of space, time, and their unification as spacetime. Just as I suspected. Scientists usually don't have much "time" for philosophy, especially its ontological branch... usually considered "metaphysical," as often expressed in this thread.

For the record, I knew quite well what ontology is about when I started this thread. Your self image as the moderator who sets me straight with the real scoop is ot founded on what I actually understand already... as in evidence in my first statement in this thread, which you have consistently assumed to be false.

(Your being able to categorize my thread as an ontological inquiry does no in itself verify that you know better than I what ontology is.

 

(My "thesis" was entitled: "Existential Freedom as a Basis for Psychotherapy." My introductory background was a deep examination of existentialism , what "freedom" means in the ultimate philosophical sense, and how ontology approaches the question of what is real and what is merely bio-robotic, cultural programing/conditioning.)

 

Just for what it's worth.

 

PS: In all honesty, I do not know what the rule against "having an agenda" really means.

Obviously all moderators here have an agenda to support what the textbooks say about "spacetime," and I have an agenda to challenge this ever-so-well-established mainstream science. This is the nature of honest dialogue and debate. Seems like a bogus "rule."

Michael

[Erasmus00]

Michael, I've several times tried to give you observable referents for a curved space. Consider, again:

 

Pick three random galaxies, draw the straightest possible line between each, and measure the angles of the resulting triangle. They will not add to 180 degrees. This is what people mean by space being curved.

 

Also, I'm starting to think that much of the problems on this thread are communication related. Please define for me with as much specific detail what you mean by the following: metric,distance,curved space, geometry.

[AnssiH]

M: Woah! "Sound" is the word for actual waves in the air caused by compressive forces... It is ontologically real, "whether anyone hears a given remote sound or not. (See "tree falling in forest" argument above.)

 

This comment reveals a rather serious terminology problem that has probably plagued this thread for quite some time, and caused a lot of the confusion.

 

"Ontologically real" is not meant to refer to things that can be validly defined. If it did, the whole concept would become meaningless. (And btw would mean that spacetime is "ontologically real" as it too can be validly defined and cast onto the unknown reality)

 

It is meant to refer to how reality actually exists behind our definitions. I.e. if I were to claim "sounds are ontologically real", what I would be claiming is that sounds are fundamental entities of reality or just exists metaphysically as "sounds". As oppose to "sounds" being a specific interpretation of a specific motion (or manifestation) of something else. In this case, fluctuations on air pressure.

 

Following that tack, "fluctuations on air pressure" are not ontologically real either, as air pressure itself is just a specifically defined measurement of specific motion of matter.

 

The questions regarding the ontological reality of "motion", that is starting to touch the subject of this thread more closely. How we see motion is a function of how we define the identity of entities that get associated with motion. There does exist attempts where a moving tennis ball is not seen as a "moving tennis ball" at all, but instead a wave-like manifestation of some sort of background, which is the thing that's identified (much like you can either identify the surface of the pond as having ontologically persisting identity, OR you can identify a wave moving across the surface as the thing with persistent identity, but ontologically speaking BOTH cannot have persistent identity)

 

If you read the post about map-territory relationship that I linked to in my first post to this thread, you will see some more explanation about why and in what sense matter is also a human definition (you can't find the wall of an atom without defining what it means to find the wall of an atom). And likewise space, including 3D euclidean form, needs to be carefully defined, before there is any sense to any assertion regarding where so-called "matter" ends and so-called "space" begins.

 

"But we all know how it is just by looking at it" is what refers exactly to those human definitions; to some useful way of interpreting reality. Our perception is that interpretation of reality.

 

-Anssi

[Michael Mooney]

Michael, I've several times tried to give you observable referents for a curved space. Consider, again:

 

Pick three random galaxies, draw the straightest possible line between each, and measure the angles of the resulting triangle. They will not add to 180 degrees. This is what people mean by space being curved.

 

Also, I'm starting to think that much of the problems on this thread are communication related. Please define for me with as much specific detail what you mean by the following: metric,distance,curved space, geometry.

 

Erasmus,

A "straight line" by definition and in the real cosmos is "not curved." Actually, the "straightest possible line" between three galaxies will describe a triangular *plane* with a galaxy at each point.

Your claim that this triangle will be on a curved surface rather than a flat plane is based on your a-priori assumption of the ontological reality of curved space in the first place, i.e., a supposed non-Euclidean "fourth dimension," often described as being "at a right angle to 3-D space. "At a right angle to volume" is one of the nonsense assumptions of non-Euclidean space, which an ontological error... reification of a concept without a real world referent.

Your exercise is just a scaled up version of the triangle drawn on a driveway (assuming earth curvature) or my sccaled up version of that with apex at a pole and base on a segment of the equator. Yes, such a "triangle" will have curved sides totalling over 180 degrees. But the "straight lines" between the points of the triangle will still be *through the earth* (or globe... the sphere), not the lines "drawn on the surface.."

 

"Metric": In the link on "The Hole Argument" a distinction was made as follows:

"If one has two distributions of metric and matter fields related by a hole transformation, manifold substantivalists must maintain that the two systems represent two distinct physical systems."

 

The article goes on to show that "substantivalism" (making spactime a substance) is a error of confusing the "metric" with the matter field. The metric field is the map, the system of coordinates, not the territory, and the "matter field" is the actual territory, the "real cosmic stuff" being mapped by the metric.

 

"Distance": The one dimensional straight line between any two geometric points or actual objects (either surface to surface or center to center.) This remains constant, independent of relativistic perspective, until one or the other or both points/objects actually move through space in relation to each other.

 

"Curved space": A misnomer. Both geometric (virtual) surfaces (spheres and parabolas for instance) and actual objects (planets, stars, etc) have *curved surfaces*, but space is not a "thing" so "it" has no "surface" to be "curved"... or any other "property"... unless you want to call emptiness... no-thing-ness... a property.... being the lack of any content at all.

 

"Geometry": Hmmm... too simple to describe...:( The "metric" which describes all three spacial dimensions (oh, and the non-dimensional point) and their shapes.

Geometry progresses from the point to the line to the plane to volume. The latter can both be described as all geometric *shapes* or have no shape, being the infinite "volume" of empty space... into which the "whole cosmos" is now expanding.

 

OK?

Michael

[maddog]

I am beginning to see why Michael is a tad frustrated in this thread. :P

 

The point of the "tree in the forest" was NOT to make some clever observation on the definition of "sound". It was intended as straight metaphor. The tree falls. It disturbs the air, sending out "waves". This it does whether or not anybody "hears" the waves. The act of "hearing" does not "change" the "wave" into a "sound". Don't confuse semantics with physics. :eek2:

 

The ontological reality can ONLY present itself to us as a philosophical insight.

It CANNOT be "observed". We CANNOT "perceive" the ontological universe as Michael has described it.

That is fine. However, when one begins to make qualifications/constraints based upon that Ontology or derive some understanding from it. You are no depending upon which has no corroboration ability. At this point you are now about to quibble upon the most

perfect place to put the deck chairs when the Titanic hits the iceberg -- like that was relevant. It is for this reason I detest Ontologies for their own ends.

 

Our "organs of perception", being as they are bound by the laws of physics, the constant speed of C, Special Relativity, etc, can ONLY perceive the "subjective universe". Mind you, everything YOU have said in response to Michael is absolutely True! ;) Nothing you have said is false!

 

It's just that you are talking about the subjective universe that we can see, touch, smell, etc. Michael is talking about a Platonic Ideal -- the Ontological Universe -- the pure Beingness of the Existence of Reality Itself. This is philosophy, not physics.

These are reverse -- the physical world is Objective. The Platonic Ideal is Subjective,

without any corroboration.

You CANNOT observe the Ontological Universe. That would require that the speed of light be infinite, and consequently, that the energy density of the universe be infinite, which is obviously false.

 

Now, I'm still not sure that Michael's secondary conclusions are correct, but I'm willing to grant him that the Ontological Universe does in fact exist, it's out there. We will never be able to "see" it, but it's out there. :dog:

On this we totally agree -- they're not. :(

 

maddog

[maddog]

:umno:

 

I hate to be picky about this, but now that I understand Michael's point of view on this "Ontological Universe Thingie" (OUT), I find that I am "compelled" to help others understand it. :)

 

The OUT is exactly one and the same with the Perceived Universe Thingie (PUT). The difference is, we can only observe the PUT. The PUT is what we observe.

:umno:

 

I do like your OUT and PUT concepts. However, I don't see them as equal. Maybe

equivalent, yet unequal. What you have created is a duality. Similar to the duality of

the wave nature of light versus the particle nature. These are also Not equal. Phenominae in one paradigm can lead to a paradox explained by the other.

I do have a similar theory I am considering about realities being bifurcated. You could

consider an Objective Outer Reality (your PUT) which can be our perceived would view.

Another view would be the Subjective Inner Reality which is not viewed (nor viewable).

Yet a duality forming some type equivalence relation between the two realities would be possible.

 

In the second scenario, you are observing the OUT. Now you can see the doors opening and closing in real time, the cat going back and forth, the windows going up and down, and all in real time. In the Everywhere Eternal Now.

The only way I can think of this as "observing" would in the "Gnostic" method that Michael has alluded to.

Now, let's go back to the real universe we live in. We can ONLY observe the PUT, due to the huge distances and the high speeds. Nothing is faster than light. We can never, never, never "observe" the OUT in "instant time". We can never, never, never see where everything is in the Everywhere Eternal Now. It is forbidden to us.

To "know" in a Gnostic way would be by some inner subjective knowing and you are right would not be observable.

 

maddog

[Erasmus00]

Erasmus,

A "straight line" by definition and in the real cosmos is "not curved." Actually, the "straightest possible line" between three galaxies will describe a triangular *plane* with a galaxy at each point.

 

Everything you wrote after this is irrelevant to what we are talking about. If GR is correct our "galactic triangle" made of the straightest possible lines we could draw will have angles that total larger than 180 degrees. What does this mean? In the Earth/driveway example you say that we could make a straighter line by punching through the Earth, can we make a straighter line in our galactic case?

 

"Metric": In the link on "The Hole Argument" a distinction was made as follows:

"If one has two distributions of metric and matter fields related by a hole transformation, manifold substantivalists must maintain that the two systems represent two distinct physical systems."

 

I'm not asking for an argument, I'm asking for what you mean when you say metric. What is your definition of a metric?

 

"Distance": The one dimensional straight line between any two geometric points or actual objects (either surface to surface or center to center.) This remains constant...

 

Your definition of distance has no measure associated with it. i.e. you have no way to turn your definition into a number. So what do you mean by "this remains constant?"

 

"Curved space": A misnomer. Both geometric (virtual) surfaces (spheres and parabolas for instance) and actual objects (planets, stars, etc) have *curved surfaces*, but space is not a "thing" so "it" has no "surface" to be "curved"

 

This is at odds with what physicists and mathematicians mean when they say curved. A curved space is a space where a drawn triangle has other than 180 degrees. (or, equivalently, a space where Euclidean geometry does not hold).

 

"Geometry": Hmmm... too simple to describe...:umno: The "metric" which describes all three spacial dimensions...

 

Before you can use this, you'll need to give me what you mean by metric. When we can agree on definitions, maybe this communication will end.

[Pyrotex]

To all commenters to my posts,

(cause I don't have time to answer each individually)

 

I heartily approve your comments and criticisms. Rat Own!

 

The PUT is the objective universe because we know it from empirical evidence.

 

The OUT is the "subjective" one (rather a wierd use of that word here, anyway....) which we CANNOT EVER know from empirical evidence.

 

There are only TWO (2) (count 'em) purported ways of "seeing" the OUT, the Ontological Universe.

 

You either have to be satisfied with a purely philosophical, Platonic "concept" -- OR

You have to "see" it in a mystic vision, a revelation from on high, a gnostic ZAP to the brain.

 

The first is marginally possible, with lots of caveats.

The second, which Michael would like us to accept, is... aaahhhh... ummm...

I'm trying to think of the technical word that goes here.

ummm...

AHA!!!

It's "BOGUS"! :) :umno: :) :) :)

 

Now, I'm sorry Michael, I really am. But gnostic mystical paranormal ZAPs to the brain are generally <<<NOT>>> the result of Cosmic Universal Transfer of Data Recieved at Infinite Velocity.

(CUTDRIV). And, that's what we're talking about here, isn't it?

To "know" the shape and content of the universe all in one fell swoop, without being limited by all that photon-carrying-data-at-the-speed-of-light-and-relativity-****. Right? :umno:

 

Correct me if I'm wrong here. I do not want to misrepresent your position.

 

But I do think we should call a spade a ... shovel.

 

There are a number of brain disorders (and drugs) that give a really convincing simulation of a gnostic brain ZAP, but I won't go into that here.

 

So, I humbly suggest that what you had was a philosophical insight of a moderately mundane kind.

 

Finally, the universe that we see with our senses and telescopes and other devices, the one we have empirical data for, doesn't behave the way your gnostically revealed universe does. Sorry.

Others here have pointed out numerous differences between the two.

 

Empirical data and observations, I'm afraid, is on their side.

[maddog]

Most of us are probably familiar with Euclid's "definitions, notions, and postulates." I know I am. But you insist on lecturing me anyway, as usual, on what I already know.

I've made no claim that the parallel line postulate is based on previous postulates.

But it is impossible to make an ontological case for parallel lines converging or diverging (as in non-Euclidean "geometry") in the "real world"... or for the shortest distance between two points being other than a straight line. Think "real world" as in "ontology" rather than "according to a metric based on curved space..." etc.

 

Lobachevsky's or Riemann's geometry is based on the the latter "metric" the ontology of which is the subject of this thread's challenge!

You claim to be up on Euclid. It is the 5th Postulate which if failing defines Non-Euclidean

Geometry. If what you are saying is that you take the 5th as nonrefutable then you are definitely

stuck back in the Classical Greek period along with Euclid! I suppose that Topology is

out for you as well.

Ontology is not a "popularity contest" between belief systems. If you apply epistemology to non-Euclidean geometry, you come up with "Here is the theoretical metric... no referent in the real world required." Well ontology requires such referents to establish the reality of "things" like curved space and dilating time as existentially extant, i.e., as actually existing in "the real world."

Taken your logic as it is and I find it hard to apply this to an Ontology of thought. Since thoughts

have no "real" "existence" in the "Real World" either. 'Cause I would like to know how much

energy is in a thought... :confused:

 

maddog

[maddog]

(My "thesis" was entitled: "Existential Freedom as a Basis for Psychotherapy." My introductory background was a deep examination of existentialism , what "freedom" means in the ultimate philosophical sense, and how ontology approaches the question of what is real and what is merely bio-robotic, cultural programing/conditioning.)

 

Just for what it's worth.

 

PS: In all honesty, I do not know what the rule against "having an agenda" really means.

Obviously all moderators here have an agenda to support what the textbooks say about "spacetime," and I have an agenda to challenge this ever-so-well-established mainstream science. This is the nature of honest dialogue and debate. Seems like a bogus "rule."

Michael

You thinking "spacetime" is a bogus rule is fine with me. Welcome to your opinion.

When you challenge a forum as to whether a concept is bonafide and then repudiate

all the evidence as not being ontological is disingenuous. Your first post hear gave the

impression of innocently ask "what is spacetime" like you were genuinely interested in

an answer. However you later posts quickly descended into an "ontological" debate

on the nature of "spacetime" and defending Euclidean Geometry as the TRUE geometry

of Nature similar to the methodology of the Flat Earth Society.

 

I truly disdain pomposity. You must hold the Guiness Book of World Records for it!

 

:confused: :confused: :shrug: :naughty: :naughty:

 

I will continue to post here. I won't consider any notion of Euclid still being "right!" and

other mathematicians wrong. Neither side is right nor wrong. Euclidean Geometry is

as valid as any other. Yet your adherence to the universe behaving in a Galillean Relativity

won't get you points either. You are welcome to believe what you want Ontology or not. Don't expect me or anyone to go far down this road if you won't agree to a

scientific method and logic. By that form a hypothesis and work towards a conclusion.

Others will do in kind. Your methodology is falling off a slippery slope fast.

 

maddog

[maddog]

"Metric": In the link on "The Hole Argument" a distinction was made as follows:

"If one has two distributions of metric and matter fields related by a hole transformation, manifold substantivalists must maintain that the two systems represent two distinct physical systems."

The article goes on to show that "substantivalism" (making spactime a substance) is a error of confusing the "metric" with the matter field. The metric field is the map, the system of coordinates, not the territory, and the "matter field" is the actual territory, the "real cosmic stuff" being mapped by the metric.

I agree from what I read of the articles (#398).

 

"Curved space": A misnomer. Both geometric (virtual) surfaces (spheres and parabolas for instance) and actual objects (planets, stars, etc) have *curved surfaces*, but space is not a "thing" so "it" has no "surface" to be "curved"... or any other "property"... unless you want to call emptiness... no-thing-ness... a property.... being the lack of any content at all.

Only valid if you take the 5th Postulate of Euclid as an Axiom (Unrefutable).

 

"Geometry": Hmmm... too simple to describe...:confused: The "metric" which describes all three spacial dimensions (oh, and the non-dimensional point) and their shapes.

Geometry progresses from the point to the line to the plane to volume. The latter can both be described as all geometric *shapes* or have no shape, being the infinite "volume" of empty space... into which the "whole cosmos" is now expanding.

Not quite. Your think is quite Euclidean. There are many "metrics" and "geometries"

that can be defined (not all continuous), some of only a Topological nature.

 

maddog

[Michael Mooney]

AnssiH,

I still don't know what you find so confused or confusing about my presentation here.

Maybe if I focus in on one point at a time... the "ontology" of sound.

 

To review:

M: Woah! "Sound" is the word for actual waves in the air caused by compressive forces... It is ontologically real, "whether anyone hears a given remote sound or not. (See "tree falling in forest" argument above.)

A:

This comment reveals a rather serious terminology problem that has probably plagued this thread for quite some time, and caused a lot of the confusion.

 

"Ontologically real" is not meant to refer to things that can be validly defined. If it did, the whole concept would become meaningless. (And btw would mean that spacetime is "ontologically real" as it too can be validly defined and cast onto the unknown reality)

 

It is meant to refer to how reality actually exists behind our definitions. I.e. if I were to claim "sounds are ontologically real", what I would be claiming is that sounds are fundamental entities of reality or just exists metaphysically as "sounds". As oppose to "sounds" being a specific interpretation of a specific motion (or manifestation) of something else. In this case, fluctuations on air pressure.

 

Following that tack, "fluctuations on air pressure" are not ontologically real either, as air pressure itself is just a specifically defined measurement of specific motion of matter.

 

You seem to be contradicting yourself. You said on one hand that "ontologically real" goes beyond our definitions and refers to "how reality actually exists behind our definitions."

 

I totally agree.

"Sound" happens in the real world as air is compressed and "sound waves" then travel through the air. This is objective reality whether anyone "hears" a given sound or not.

But then you followed with:

" if I were to claim "sounds are ontologically real", what I would be claiming is that sounds are fundamental entities of reality or just exists metaphysically as "sounds". As oppose to "sounds" being a specific interpretation of a specific motion (or manifestation) of something else. In this case, fluctuations on air pressure."

 

My statements immediately above do not claim that "sounds are fundamental entities of reality or just exists metaphysically as "sounds". (Fundamental entities??) Just that sound waves a real physical (not metaphysical) effects of real forces compressing real air... in the real world... objectively... independent of our definitions or perceptions. They are obviously "real", not just "specifically defined measurement " of air pressure, etc.

 

Maybe just one step at a time here, OK?

 

Michael

[Pyrotex]

A quick note on straight lines in the universe.

There is the Platonic Ideal of a straight line, and I believe this is (I think) what Michael believes the universe can be "drawn" with.

 

There is the Constructed or Observed straight line that we (as non-deities) are limited to dealing with.

How do you define a straight line?

There is only one way I've ever heard of -- use the flight-path of a photon. Photons always take the minimum energy path between two points. That's also the minimum time path. It's also the path of zero effort, meaning that no additional force or energy is required by the photon. This is probably the ONLY "unique" path in our universe between two physical points.

 

But photons are affected by the Sun's gravity! :confused:

 

To make a long story short, the Sun doesn't "pull" on the photon with a force, but it distorts the normally "flat, Euclidian" space that the photon normally travels through. The path skirting the edge of the Sun, "curved" to our way of thinking, is STILL the minimum energy path between two points. That's also the minimum time path. It's also the path of zero effort, meaning that no additional force or energy is required by the photon.

 

We're in the same situation as Copernicus. Assuming that the Sun was the center of our solar system turned out to be a "simpler" explanation, that required "simpler" rules.

 

Assuming the Sun "curves" space so that the photon's path is ALWAYS a "straight line" with respect to the photon's point of view -- turns out to be a "simpler" explanation, that requires "simpler" rules

[Michael Mooney]

Erasmus:

Everything you wrote after this is irrelevant to what we are talking about. If GR is correct our "galactic triangle" made of the straightest possible lines we could draw will have angles that total larger than 180 degrees. What does this mean? In the Earth/driveway example you say that we could make a straighter line by punching through the Earth, can we make a straighter line in our galactic case?

 

Irrelevant huh? Seemed to be replying spot on to your exercise as having been addressed in previous "triangle" exercises and then answering your specific demand for my definitions of specific words/phrases.

 

If GR's *assumption* about the "curvature of space" is wrong, then the shortest distance between any two points or objects anywhere, on whatever scale, is still a straight line... or three of them in the case of "connecting the dots" or the galaxies... not cuved lines. Please understand that non-Euclidean "four dimensional space" (as a part of GR) is not, as you assume, already established as indisputable fact!

 

So re: " In the Earth/driveway example you say that we could make a straighter line by punching through the Earth, can we make a straighter line in our galactic case?"...

 

Yes, regardless of scale, a straight line is still not a curved line, and a curved line is the longer line or linesr between the galaxies. This is based on an ontology that "space itself" is simply empty volume, not actually an "itself" with any properties, including curvature.

 

I'm not asking for an argument, I'm asking for what you mean when you say metric. What is your definition of a metric?

I answered this in my next paragraph after the quote, as follows:

The metric field is the map, the system of coordinates, not the territory, and the "matter field" is the actual territory, the "real cosmic stuff" being mapped by the metric.

The metric field upon which GR is based assumes not only that space is a "thing" which curves but that time is a thing that dilates. You assume both are true... that the "spacetime metric" is valid without even entering the ontological debate.

(See references above to Doctordick's observations in this regard and AnssiH's concurrence.)

 

M: "Distance": The one dimensional straight line between any two geometric points or actual objects (either surface to surface or center to center.) This remains constant...

E:

Your definition of distance has no measure associated with it. i.e. you have no way to turn your definition into a number. So what do you mean by "this remains constant?"

Distance exists whether it is measured or not. If we want to measure the distance between two objects, we must first agree on a unit of measure. Take your pick. There is an objective, well known and precisely measured distance between, say, earth and sun. It of course varies with earth's orbital path at any given moment. It can be stated in earth diameters, miles, kilometers, light minutes... or whatever.

 

M: Curved space": A misnomer. Both geometric (virtual) surfaces (spheres and parabolas for instance) and actual objects (planets, stars, etc) have *curved surfaces*, but space is not a "thing" so "it" has no "surface" to be "curved"

 

E: This is at odds with what physicists and mathematicians mean when they say curved. A curved space is a space where a drawn triangle has other than 180 degrees. (or, equivalently, a space where Euclidean geometry does not hold).

 

You are not engaging in the ontological debate on spacetime here by simply asserting that my challenge is "at odds" with the "accepted" doctrine, metric, whatever of "curved space" as an element of "spacetime." Of course it is!

 

M: "Geometry": Hmmm... too simple to describe... The "metric" which describes all three spacial dimensions...

 

E:Before you can use this, you'll need to give me what you mean by metric. When we can agree on definitions, maybe this communication will end.

 

Well... I "used it" already, and I clarified what I mean by "metric"... "the map, not the territory" pages ago and again recently in reply to you.

 

Are we done yet?

Michael

[Michael Mooney]

General comment:

So... this forum will not sustain a *respectful dialogue* or debate on what spacetime actually is without indulging in the usual "know it all" attitude of emprical science and its materialistic worldview condescending with smug smirks on some faces and malicious mystic bashing by others, like "maddog", fighting his way to the top of a bloody battle/dogfight... to the top of the heap, his own mind.

 

I remind you all that I have never claimed that my visions, and resulting cosmology are founded in empirical evidence or even that they are "scientific." But, as philosophy of science, the question remains, "Is there an objective universe independent of relative perspectives or perception by intelligent life forms?" If you say "yes", as I do, then others can demand how you know this to be true without invoking your perceptions. It is not allowed to say that the objective existence of the universe is "self evident", as is my gnosis of the universal NOW and omnipresent consciousess is self evident.

 

So, tho Pyrotex dodged the question with a wink and a grin, it still remains. Are there any mature "philosophers" of science in this forum?

 

I will not engage in this vicious, snarling dogfight.

Michael

[freeztar]

Michael,

 

It seems that the only response that will make you happy is a denunciation of the concept of spacetime.

 

I fully understand your ontological arguments against spacetime. The gnostic sense of the eternal now is not lost upon me.

 

But...what then?

 

If everyone suddenly agreed with you, what would be the point of continuing this dialogue?

In this respect, I wholeheartedly agree with DoctorDick and AnssiH.