What is "spacetime" really?

[maddog]

Hi Michael,

okay, I went back and read several of your posts, including the one you specified.

 

How in the world did this thread get so gnarled up? :lol: :hihi: :lol:

 

oh, well. :lol: so, is the whole "issue" just the reification of "space-time"?

Is that what this is all about?

 

:huh: :doh:: :D :lol: :(

 

I can address that to some extent if that is the issue here.

and I apologize for the confusion. :hihi:

I am beginning to think so myself. I might have missed something (using Wiki's definition of

"reification" I don't see how physicists using the concept of spacetime in GR or allowing

Euclid's 5th Postulate to be ignored is in some way "reifying" spacetime. It's a concept,

pure and simple and it works it makes the theory agree with the data. When it stops

doing this we look for a new theory with new concepts.

 

Good example is attempting deal with GR on a Planck Scale using concepts from QFT.

Penrose so aptly puts in his book already mention in my posts above (doesn't work well). Thus is the desire to add to GR in this domain. One given is that spacetime

must have a metric that discrete like QM.

 

maddog

[maddog]

At the beginning of the thread the argument was: "why are you treating my question philosophically?", and the argument has now become "why won't anyone address my philosophical question?" The only constant through all that is the argument, and that has no purpose.

 

~modest

Modest,

 

It was that reason why I made the joke reference to the Monty Python skit about an Argument.

 

maddog

[maddog]

Michael,

 

I have one simple question which you can answer or not.

 

Do you feel that a Euclidean Geometry is the only valid geometry that can represent space

in any way and that the Euclid's 5th Postulate must always be true ? (Yes/No)

 

I am just curious.

 

maddog

[Michael Mooney]

Hi Michael,

okay, I went back and read several of your posts, including the one you specified.

 

How in the world did this thread get so gnarled up? :lol: :hihi: :lol:

 

If you examine all details I mentioned in post #462 and then examine all criticisms which Modest just made above... in detail, point by point, then you will see exactly [i"]how this thread got so gnarled up."[/i] I have countered his *every argument*, sometimes several times, yet he repeats the same links and his attending arguments over and over. t We have already debated all the issues he just raised again, yet it is as if he didn't register a word I've said in each and every case.

 

He drools with contempt, disrespect and arrogant condescension in his every reply to me... always assuming he has the "right answer, which I am just too stupid to understand.

I am ready for a break or "permanent leave" here, but whether that is immediate, or I do come back, I will refuse to ever again answer one of his posts.... for the very obvious reasons just explained.

 

He even hammers on my original discontent with this assigned section, tho I've granted his correctness and my mistake in that regard repeatedly... along with my well verified misgivings (that ontology "don't get any respect" among most hard core scientific materialists .) He is a disrespectful basher.

 

oh, well. :lol: so, is the whole "issue" just the reification of "space-time"?

Is that what this is all about?

 

If you include the specifics I just mentioned above**, then, yes it is about making something out of nothing... "spacetime."

 

** What then? Then "curved space" would be replaced, in all textbooks on relativity with "curved trajectories of objects traveling through space" without reifying "space itself" as a "thing" with curvature and shape.

Likewise "time dilation" would be replaced with precise descriptions of the conditions under which clocks slow down, and science could then focus on investigating why forces which change a clock's velocity make the rate of atomic decay slow down... rather than reifying "time" as some "thing" which "in itself" slows down.

Then I would be a very happy camper.

 

Oh... also... relativity would "get over" the bogus claim that distances vary with relative perspective rather than being physical facts all by themselves. And "length contraction*" will go out the window along with "time dilation."

(* Not referring to a "rod" being compacted by accelleration.)

 

:huh: :doh:: :D :lol: :(

 

I can address that to some extent if that is the issue here.

and I apologize for the confusion. :hihi:

 

Maybe it's time for that break, but thanks anyway.... or go ahead if you like.

Michael

[Pyrotex]

...If you include the specifics I just mentioned above**, then, yes it is about making something out of nothing... "spacetime."

...Maybe it's time for that break, but thanks anyway...

You're welcome.

 

For starters, I apologize again. it seems I did not read ALL the posts, and those I did, I didn't always read in chronological order. And I still haven't. My time is at a premium these days. :doh:

 

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.

 

To some extent, we are perfectly justified. Objects have attributes. For example, the photon is massless, the elm tree is 48 feet tall, the house is blue and contains furniture, and the woman is 26 years old.

 

Space-time has attributes. For one, it has volume; in fact, space can be arbitrarily segmented into any number of regions, each having any desired volume. Or we can measure the volume of a region of space.

 

Space can "contain" other objects. "locations" can be idenified within a region of space, and the distance between those points can be measured.

 

So, even though "space" is usually regarded as empty, or even as "nothing", it is not "nothing". Only a "something" can have attributes, IMHO.

 

Space has an electrical permitivity and a magnetic permeability. Constant, non-zero values. How about that? Space even has an index of refraction, although it is 1.000, and probably by definition, so that doesn't count.

 

It appears that it is space itself that defines the speed of light -- NOT some inherent property of the photon.

 

It appears (according to Einstein) that space, in some "geometrical" way that we usually refer to as "curvature", manifests Gravity. However, the word curvature is quite frankly arbitrary; we could just as easily have said that it is the "bloximetry" of space that manifests Gravity. That gets rid of some of the baggage, and makes it clear that we have no clue what "bloximetry" is.

 

And finally, at the scale of the teensy-tiny, space even has quantum properties, appearing to be, as one science author said, "frothy, like an ocean of soap suds".

 

Okay. That's my first move. Anything here worth your comments or criticisms? Or have I totally missed the question yet again? :hihi:

[Michael Mooney]

Pyrotex,

Thank you for your civil and apparently sincere and respectful reply.

I'll reply as usual in context in bold for contrast.

 

You're welcome.

 

For starters, I apologize again. it seems I did not read ALL the posts, and those I did, I didn't always read in chronological order. And I still haven't. My time is at a premium these days. :(

Thanks for your efforts to understand what I accept of relativity and what I reject. My critique sometimes requires subtle discernment, especially regarding the ontology of "what is it, really.?"

 

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.

 

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.

 

To some extent, we are perfectly justified. Objects have attributes. For example, the photon is massless, the elm tree is 48 feet tall, the house is blue and contains furniture, and the woman is 26 years old.

 

Agreed. Objects have attributes. If "spacetime" is not such an object, but rather the emptiness *between objects*... on all scales, micro to macro, then "it" is not an "it", even tho we call "it" an "it," and has no attribute... unless you call emptiness or no-thing-ness an attribute... which is a stretch.

 

Space-time has attributes. For one, it has volume; in fact, space can be arbitrarily segmented into any number of regions, each having any desired volume. Or we can measure the volume of a region of space.

 

OK, there is the "stretch." If volume is emptiness and extents infinitely (no "boundary" to space) then it is just the arbitrary designation of this volume (with this shape and size) and that volume (with that shape and size) that is *assigned such attributes* by the said arbitrary "designation."

 

Space can "contain" other objects. "locations" can be idenified within a region of space, and the distance between those points can be measured.

 

Of course space contains objects and the rest just mentioned. Is this an "attribute," that emptiness can can contain things... obviously no longer empty at each location of a thing? Let's not argue the semantics of the meaning of "attribute", ok? If space is empty... one conclusion... If it is a thing "itself" (curving, expanding, contracting, having shape, etc.), then those would be "it's" attributes... which I say are ontologically "bogus." ;) (I like that word!)

 

So, even though "space" is usually regarded as empty, or even as "nothing", it is not "nothing". Only a "something" can have attributes, IMHO.

 

So here you assert that calling space emptiness is in error, 'cuz in your belief system "it" is "not 'nothing'" Yet you will not say what "it" is other than arbitrary volumes and shapes and how real "things" *in space* act.

 

Space has an electrical permitivity and a magnetic permeability. Constant, non-zero values. How about that? Space even has an index of refraction, although it is 1.000, and probably by definition, so that doesn't count.

 

Yes, a vacuum containing no "thing" (as nearly as possible) "permits" magnetic attraction across it, even in a near vacuum in a lab. This does not validate that the vacuum is not empty but filled with a mystery medium, "space."

 

It appears that it is space itself that defines the speed of light -- NOT some inherent property of the photon.

 

How is it that you assume that light does not travel at its well known constant speed through empty space? How is it " NOT some inherent property of the photon" to travel from its source through *empty space* without some help from said "space" to "define" its speed. You are simply not addressing such ontological questions. Iow, how does "space" define lightspeed rather than light simply traveling at lightspeed... period?

 

It appears (according to Einstein) that space, in some "geometrical" way that we usually refer to as "curvature", manifests Gravity. However, the word curvature is quite frankly arbitrary; we could just as easily have said that it is the "bloximetry" of space that manifests Gravity. That gets rid of some of the baggage, and makes it clear that we have no clue what "bloximetry" is.

 

We know that gravity is the force of attraction between masses (and that it bends light as if it had mass.) Mass "manifests" this force by being massive. The question of how this force is propagated through space (with or without "attributes") is still an open question. Einstein "attributed" curvature to space as a convenient "metric" with which to describe trajectories of *objects through space* as effected by gravity.

Ontologically, there is no foundation whatsoever to posit that, "therefore, curved space manifests gravity."

 

We could just as well say that it is "god's omnipresence throughout space which propagates (or manifests) gravity"... but that would not be scientific. ;)

 

And finally, at the scale of the teensy-tiny, space even has quantum properties, appearing to be, as one science author said, "frothy, like an ocean of soap suds".

 

Yup, theorists can arbitrarily "attribute" the "property" "frothiness" to the empty space within and between atoms as well in like manner to "the attributes of space" on macro scale as above. The same ontological argument applies.

 

Okay. That's my first move. Anything here worth your comments or criticisms? Or have I totally missed the question yet again? :(

 

No, not "totally"... just partially, as detailed above. But thank you for not making me into a pathetic "hand waving," raving caricature who is here grandstanding for the sake of argument.

Boo hoo!:) I feel so misunderstood! ;)

 

Michael

[Michael Mooney]

Michael,

 

I have one simple question which you can answer or not.

 

Do you feel that a Euclidean Geometry is the only valid geometry that can represent space

in any way and that the Euclid's 5th Postulate must always be true ? (Yes/No)

 

I am just curious.

 

maddog

My experience is that "space" is three dimensional, i.e., distance, area, and volume.... and that ultimately space has no limit or boundary. The "burden of proof" for more spacial dimensions (*in the real world*... not just computer-generated models!) is on the "non-Euclidean space" theorists.... ontologically speaking... not just "my opinion."

 

I would also like to clarify that "geometric shapes" can take the whole variety of forms as we all know... but that fact does not mean that "space has shape." The "stuff in space" has shape, and ultimate, cosmos, as it expands out *into space* has (whatever) shape. I "see" cosmos as expanding spherically, balloon-wise (with a "thickness of rubber" extending beyond our "cosmic event horizon!")..., outward from the Bang or series of Bangs... tho the non-Euclidean folks thingksuch a cosmology is "outdated." (The jury will remain "out" on that one... maybe "forever!")

 

Michael

 

Parallel lines never intersect. Any representation of parallel lines that has them intersecting misrepresents what the phrase "paralell lines" means.

[freeztar]

"Spacetime is not a thing"...check

"The ontological arguments for spacetime are separate from our perceived measurements that are attributed to spacetime"...check

 

Your argument is all too clear to me now, but it raises a question in my mind. Consider the big bang. The universe is considered to be everything that emerged from this cosmic expansion (empty space, blackholes, stars, clouds of gases, etc.).

 

What if we consider that which exists (or rather doesn't exist) outside of the universe? I know this is an invalid argument in physics, but this is philosophy. :)

 

To me, logically, it would imply that space actually is a thing, a something that is separate from the no-thing that exists outside of the universe.

 

I'm curious as to your thinking regarding the CMBR. Also, we have performed measurements that show that space is not really empty (iow, it's not a perfect vacuum). Hence, space can be seen as a "container" which holds H atoms and various other particles.

 

I know this isn't a strong argument for the ontology of spacetime (in fact you might well say that it is not an argument for the ontology of spacetime (OoST) at all), but it's interesting to consider and may provide clues into the OoST.

 

Actually, thinking about it some more, it does not seem that space is really the problem (which has been the topic of several of the latest posts). It seems that time is a much bigger hurdle for the OoST. Intuitively, it seems that this is where the OoST needs to be attacked. Iirc, this was the same line of thinking that made me post a link to the "What is time" thread for your review. Time seems much more tenuous than space from a philosophical standpoint, imho.

[Michael Mooney]

Hi freeztar,

Good questions. I'll do my best at honest answers, as I see things.

 

"Spacetime is not a thing"...check

"The ontological arguments for spacetime are separate from our perceived measurements that are attributed to spacetime"...check

 

Your argument is all too clear to me now, but it raises a question in my mind. Consider the big bang. The universe is considered to be everything that emerged from this cosmic expansion (empty space, blackholes, stars, clouds of gases, etc.).

 

I am very focused on the meaning of words. What do you mean by "all too clear?"

 

I "see" the cosmos (real stuff we know about... as contrasted with " the universe"... all there is...) as exploding, in a series of explosions, like supernovae, from balls of matter returned from the outward expansion by gravitation... a kind of cosmic "juggling act." So I think my cosmology is quite different from what you suggest already.

 

What if we consider that which exists (or rather doesn't exist) outside of the universe? I know this is an invalid argument in physics, but this is philosophy. :)

 

If we call "the universe" "all there is" then there is nothing but infinite space beyond what we can call "Things Which Exist." Outside our cosmic event horizon, "what exists" is an eternally open question.

 

To me, logically, it would imply that space actually is a thing, a something that is separate from the no-thing that exists outside of the universe.

 

Einstein's genius and his validation in the results of "E=MC squared (The Bomb) hypnotized "science" into the new religion of reified spacetime as an axiom of relativity. So "Spacetime" became a "thing" in the minds of all believers. The new religion could be called TIDE... Thoroughly Indoctrinated Disciples of Einstein. ;) Just kidding... mostly.

No-thing-ness is that which lies between all "things'... energy systems... on all levels... subatomic, between atoms, between molecules... etc. to between all "objects" on macroscopic scale. Beyond the "whole cosmos" (as I have "seen" it is infinite space... which probably "contains" infinitely more cosmi.... as far as the omnipresent "I" can see. But that must remain speculative.

 

I'm curious as to your thinking regarding the CMBR. Also, we have performed measurements that show that space is not really empty (iow, it's not a perfect vacuum). Hence, space can be seen as a "container" which holds H atoms and various other particles.

I'm nearly 64 and am not presently aware of what the acronym "CMBR" stands for. Please spell it out. Of course "space is not empty." It contains the whole cosmos and all little parts thereof. Each atom takes its place *in space*, and where each "thing" exists, space is not empty but occupied by even single hydrogen atoms... with may be "zillion" of light years apart... the empty space between them.

 

I know this isn't a strong argument for the ontology of spacetime (in fact you might well say that it is not an argument for the ontology of spacetime (OoST) at all), but it's interesting to consider and may provide clues into the OoST.

 

Actually, thinking about it some more, it does not seem that space is really the problem (which has been the topic of several of the latest posts). It seems that time is a much bigger hurdle for the OoST. Intuitively, it seems that this is where the OoST needs to be attacked. Iirc, this was the same line of thinking that made me post a link to the "What is time" thread for your review. Time seems much more tenuous than space from a philosophical standpoint, imho.

 

Yes. If space can be called the emptiness between things, as "above" (this whole thread) then "time" becomes the issue of debate. Please re- read my ontology of time at the end of the thread, "What is Time"... and get back to me on that.

I'll go back and find your post in that thread in the meanwhile, an we can pick up the dialogue on "time" from there.

 

Thanks for an intelligent reply.

Michael

[freeztar]

Hey Michael,

 

I highly recommend using quote tags when quoting others. It makes it much easier to read and also to respond. Here are my responses.

 

I am very focused on the meaning of words. What do you mean by "all too clear?"

 

That simply means that I understand what you are saying. It's clear to me what you are trying to convey. The "all to" qualifier expresses that it's a revelation that exceeds the common standard (ie most people still have not caught on).

 

I "see" the cosmos (real stuff we know about... as contrasted with " the universe"... all there is...) as exploding, in a series of explosions, like supernovae, from balls of matter returned from the outward expansion by gravitation... a kind of cosmic "juggling act." So I think my cosmology is quite different from what you suggest already.

It does seem that we have different views here, but I'm unsure what exactly you mean by your words. Are you suggesting something like a cyclic universe theory?

 

If we call "the universe" "all there is" then there is nothing but infinite space beyond what we can call "Things Which Exist." Outside our cosmic event horizon, "what exists" is an eternally open question.

I agree it remains speculative. It's a thought experiment and has no ontological validity in and of itself. But, if one can imagine infinite nothingness, then it can be used to contrast what we consider the ontological reality of all "things".

 

Einstein's genius and his validation in the results of "E=MC squared (The Bomb) hypnotized "science" into the new religion of reified spacetime as an axiom of relativity. So "Spacetime" became a "thing" in the minds of all believers. The new religion could be called TIDE... Thoroughly Indoctrinated Disciples of Einstein. Just kidding... mostly.

 

Well, I can certainly understand the objection from an ontological standpoint, but we must remember that Einstein did not approach the subject this way. His 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.

 

No-thing-ness is that which lies between all "things'... energy systems... on all levels... subatomic, between atoms, between molecules... etc. to between all "objects" on macroscopic scale. Beyond the "whole cosmos" (as I have "seen" it is infinite space... which probably "contains" infinitely more cosmi.... as far as the omnipresent "I" can see. But that must remain speculative.

I'm glad you mentioned sub atomic space because I was making the mistake of only thinking about this problem on the macroscopic level.

 

This raises some interesting thoughts in my mind. If we consider an electron orbiting a nucleus, there is a bunch of space between the two (relative to their sizes). Even though we cannot accurately pinpoint where exactly the electron is at any given moment, we know that it must be separate from the nucleus. The forces that dictate this extend into the space between the two. 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).

 

I'm nearly 64 and am not presently aware of what the acronym "CMBR" stands for. Please spell it out. Of course "space is not empty." It contains the whole cosmos and all little parts thereof. Each atom takes its place *in space*, and where each "thing" exists, space is not empty but occupied by even single hydrogen atoms... with may be "zillion" of light years apart... the empty space between them.

CMBR is a common acronym in physics that stands for Cosmic Microwave Background Radiation. Wiki has a nice article on it.

 

Yes. If space can be called the emptiness between things, as "above" (this whole thread) then "time" becomes the issue of debate. Please re- read my ontology of time at the end of the thread, "What is Time"... and get back to me on that.

I will do that. I think now is a perfect "time" to review that thread. ;)

 

I'll go back and find your post in that thread in the meanwhile, an we can pick up the dialogue on "time" from there.

 

That sounds good. :)

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.

[watcher]

If we call "the universe" "all there is" then there is nothing but infinite space beyond what we can call "Things Which Exist." Outside our cosmic event horizon, "what exists" is an eternally open question.

I agree it remains speculative. It's a thought experiment and has no ontological validity in and of itself. But, if one can imagine infinite nothingness, then it can be used to contrast what we consider the ontological reality of all "things".

 

if that is the case then an infinite empty no thing space is not ontologically satisfactory.

because a nothing does not explain how things in it begins to exist.

[freeztar]

if that is the case then an infinite empty no thing space is not ontologically satisfactory.

because a nothing does not explain how things in it begins to exist.

 

:)

 

Good point, but I think it's important to consider duality. We can't know bad without good. We can't know hot without cold. It follows that in order to examine ontology, there must be some contrast.

[watcher]

My experience is that "space" is three dimensional, i.e., distance, area, and volume.... and that ultimately space has no limit or boundary.

 

some entities does not experience 3 dimensional space. sub atomic particles has 2 or even only 1 degree of freedom. photon has more that 3 degree of freedom or worse it has no respect for 3d space at all.

 

you cant based your ontology on your experience. you are not the universe.

and different entities experience space differently than you do. you only experience 3d space as an evolutionary adaptation. there is nothing ontological about 3d space. we experience being stationary or at rest. does it mean we are not in motion?

 

The "burden of proof" for more spacial dimensions (*in the real world*... not just computer-generated models!) is on the "non-Euclidean space" theorists.... ontologically speaking... not just "my opinion."

 

mathematical proofs are more reliable than experience.

otherwise we would still believing that earth is flat , still and the center of the universe,

these are our common experiences after all.

 

Yes. If space can be called the emptiness between things, as "above" (this whole thread) then "time" becomes the issue of debate. Please re- read my ontology of time at the end of the thread, "What is Time"... and get back to me on that.

 

for the convenience of all...why don't you just post here your take on what is time, just one paragraph would suffice. thanks

[watcher]

:)

 

Good point, but I think it's important to consider duality. We can't know bad without good. We can't know hot without cold. It follows that in order to examine ontology, there must be some contrast.

i agree, but that is why nothingness cant be ontologically satisfactory because it has no meaning without the idea of somethingness. it is already part of the duality and therefore not a summation of the whole. ontologically satisfactory must be irreducible and whole from which things can begin. empty space is not. it needs things for it to have a meaning and perceived as nothing.

 

the truth is that nothingness as an ontology is the mother of all reification. its a dead end to ontology.

[watcher]

Thank you. Please explain to Watcher that "Now" is perpetually ongoing (everywhere)

 

the concept of now as " perpetually on going " implies motion. motion therefore is more ontologically satisfactory because an imaginary time that is perpetually ongoing is ridiculous.

 

not a static snapshot of a cosmos without movement.

 

i said now as a perception of being at rest in time is self evident and self verifiable. if your now is dynamic, the more time is not imaginary and space ain't emptiness.

 

there is no such thing as a dynamic nothing.

[Erasmus00]

The "burden of proof" for more spacial dimensions (*in the real world*... not just computer-generated models!) is on the "non-Euclidean space" theorists.... ontologically speaking... not just "my opinion."

 

Lets not talk about more spatial dimensions, as no one claims there is any evidence for them as yet. Lets instead talk about curved three dimensional space- you claim to accept the conclusions of GR, just not the "reification of spacetime". One of those conclusions is that a triangle drawn between three galaxies will have other than 180 degrees? What does this mean? You are repeatedly ignoring or redefining this inquiry. If you cannot draw a triangle with 180 degrees, what does this tell you? Further, you draw a circle, and find that its ratio of circumference to diameter is not 3.14.. What does this tell you?

[watcher]

If you cannot draw a triangle with 180 degrees, what does this tell you?

 

that a straight line in outer space is just a wishful thinking? hahahahahaha