owl

In my opinion it is not correct. (The emphasis goes for every thing I say. It should 'go without saying' for all of us.) "For the person flying by" then defines reality from his perspective. Idealism. The distance between Sun and Earth does not, in fact, change, "for" any hypothetical observer. This is idealism and it makes "reality" dependent on how observers see it, however limited their/our means of perception. No, in reality, Earth and Sun will remain about 93 million miles away from each other, on average, regardless of the homosapient model or the math.

I really don't give a damn who agrees with me. I just say it as I see it. Have done so all my life. Not likely to change that custom anytime soon.

My challenge to the theory is based on its reference to curved spacetime as the agent (medium, 'whatever...') which transfers the force of gravity from one mass to another... (and I challenge "length contraction" on world/cosmic scale.) My post 137 cited quotes from those maintaining that it is such a medium and Brown & Pooley's criticism of that assumption. This is an example of ontology's relevance to science. Btw, before I take off for the weekend (or while I am gone) will you please answer the following, now posed for the third time... very relevant to the "length contraction" part of relativity theory: “Do you really, truly deny that "...the distance to the Sun (remains) around 93 million miles, regardless of who is flying by at whatever speed measuring it?"... or that a squished nearly flat shape of Earth is equally valid with the well established nearly spherical shape?

Cap 'n R: I have studied general relativity *theory* minus the math for many years. Your assumption that I have not is false. There are other *theories* for how gravity works than GR’s “curvature of spacetime" (including quantum theory of “gravitons," recently discussed), so please do not continue to present it as a proven fact that I simply don’t understand. Thanks. Swansont, The rule you cite is based on non-Euclidean geometry which is not above criticism. It has replaced 3-D space (plus time) with various mental, conceptual models (manifolds) which still require ontological verification as to what they represent in the real world... which makes it part of this thread’s focus. For openers, Euclids’ fifth postulate has not been disproven, only sidestepped by claiming that, in a math model, parallel lines will intersect “in infinity.” In the real world, if lines intersect, they are not parallel lines. Second, the shortest distance between two points is still a straight line.* You can project a straight line onto a curved surface, and that projection becomes a curved line on that surface. But, as I said, ontology questions whether or not space it is anything that can have the property of curvature. It is not an established fact, i.e., that space is curved and has form (flat, parabolic or spherical,) though the *stuff in space* is distributed in whatever debatable form. These are fundamental questions asked by ontology, a division of the philosophy of science in which you have no interest, yet you claim expertise. Btw, the shortest distance between two points on a sphere is still a straight line through the sphere, point to point. The “rule” that the line must stay on the surface is only in the non-Euclidean, “space is curved” *model*. Finally, you challenged me to show who is claiming that spacetime is a medium. I quoted a few examples (and criticisms of them) in my focus on specifics in the Brown and Pooley paper, which you dismissed as a couple of philosophers expounding on varieties of theoretical categories (edit: principle vs constructive.) You never responded to those examples, which you had demanded. (Edit: “ Exactly. In fact they criticize those examples quoted which assert that it IS a medium of some sort. I agree.) I never said that there are no wrong answers in philosophy. Idealism... that reality depends on observation is wrong. And the conclusion, based on idealism, that Earth’s shape and the distance between (and length of) objects in the natural world depends on observation is also wrong. Glad to hear it. You will be happier sticking to the physics section and the axioms that you have learned as facts than trying to debate philosophy of science in this section. I in turn intend to stay out of the physics section. ( Cite the instance or retract.

Are you absolutely sure that photons are absolutely zero mass? I know the difference between the “momentum" of light, as with the box of mirrors experiment and laser gun recoil, solar wind, etc.... and ‘resting mass’ as applied to light in this case, but of course photons can not be arrested to measure ‘at rest mass.” In other words, the question remains, how can ‘mass-less light’ be “attracted’ by mass? If curved space is only a concept and not an operative entity, how is light bent by mass? I suspect that the answer lies in a not-quite-zero photon mass... which would, of course , violate the assumed “light speed limit” for “mass”, however infinitesimal. (Follow-up) Swansont; post 133; It was not a formal survey but a philosophical perspective; that a PhD in physics requires a lot of “right answers*” to pass all the tests. *(Textbook physics.) I was never burdened with those requirements. Just a difference in backgrounds here... relevant to ”credentials” as positive ad hominem support for arguments... i.e., not relevant at all.

Holy smoke! A new low in lack of communication! I have always argued that regarding "the fabric of spacetime," "The emporer has no clothes"... nothing there but the word. Brown and Pooley were discussing what spacetime is *supposed* to be, not, like myself, proposing that 'it' Is anything. That is my point. Cap'n R seems to agree.. As above, they argue that 'it' does not exist, not that 'it' IS something. They make the case that 'it' does not exist. What was that about me being "obtuse?" No, certainly nothing personal! Of course not. If you were actually saying that I am obtuse, that would be another personal ad hominem attack, in which of course you never indulge. Btw, I quoted quite a few substantive arguments above and you didn't reply to9 any of them. Ontologically, space is the empty volume between things, not counting forces as "things" for the moment. It has no surface. When speaking of a straight line, I recognize no such rule. The shortest distance between two points on the surface of a sphere is not along its surface but straight through it from one point to the other.

Editing problems... sorry.

Cap 'n R, I think this exchange is really getting to the essence of my ontological inquiry into 'spacetime': Me: You: Now, if you will just answer my bolded question above. Meanwhile, back to the Brown and Pooley challenge and Swansont's reply. Warning: The time has come to shift from generalities to specific details in this discussion, so maybe it should continue, after this, in my "Spacetime, the Scholarly Debate" thread. He answered my bolded question as follows: "Yes," the equations would be different without a non-existent entity, spacetime mediating... er... whatever a non-medium does? Yes. See below, but first, you also said: In fact they make the case that it is irrelevant to the math. Here are some quotes.(Btw, the focus was not just on whether relativity is a principle or constructive theory. The quotes below are from before that section of the presentation.)... my bold as usual and parenthetical interjections: The last statement would then require an analysis of the meaning of the "affine geodesics" involved. Anyway it involves "the generalization of the notion of "a straight line to curved space" (Wiki, I think, forgot to footnote) and that already assumes space curvature. (Edited for run-together transcription.) But, in the real world, the shortest distance is straight through the globe, not on the surface... The difference again between conceptual models and the 'real world'... more ontology.

Very "interesting." Good. Could 'it' just as well be called "whatever mass effects that then effects other masses," "whatever..." for short? Or why not just let mass attract mass without an unknown medium in between? Would the equations be different? Then quantum theory of gravity could just call their "graviton" (an alternative model/theory) "whatever-G" for whatever makes gravity work in "our model." Quite so. No objection to that part. Is this another argument by ridicule? If I don't like the tie died rabbit pelt metaphor, I can have a brown, fuzzy "whatever..." that smells like carrots? Can I get that in rainbow colors and tasting like mangos? But seriously folks! A paper on what spacetime IS was published by Brown and Pooley (cited many times.) They seriously charged that the whole concept was "parasitic" upon the existing observable material phenomena, asked what features of spacetime guided objects and light in curved paths, and concluded, as far as I can tell, that "it" added nothing to our understanding of gravity. (Paper title: Minkowski's spacetime, a glorious non-entity.) (This in case anyone here thinks that "what it is" matters anymore.) Well, science asked (something like) "what is an atom?"... and ended up with the atomic chart of elements, which added immensely to how we understand the material world and "what it is made of" in very specific detail, element by element. Of course the "what" was not settled with "atoms" as little billiard balls of matter. So subatomic physics went deeper and smaller... etc. But science is still asking what matter and energy IS at our deepest levels of understanding, even if you disdain the question as mere metaphysics. Is, 'what is a graviton?' also an unanswerable question? Then both camps can just shout their word for (whatever.. makes gravity work) at each other. "Spacetime!" "No, gravitons!" Then maybe the winner could be who shouts the loudest... or wins a worldwide "our favorite physics" popularity contest. (Just kidding.) Or... each could present what the hell each buzz-word means... i.e., (grimace!) what it is in the world as a transmitter of the obvious force of gravity. But I wax philosophical. Good night.

I must admit that you've got me there. I could cop to its common usage here (ad hominem) and admit the influence of context. But I do not apologize for my respect for credentials as I see their merit. I refer to credentialed authorities as everyone else here does. My 178 score on the WAIS does not entitle me to any personal ad hominem credentials other than the ability to think for myself, not programmed to give the "right answers" in physics classes to earn a PhD. Nothing personal. One wonders if model-creation without reference to empirical facts has been progress or regress. "The fabric of spacetime" seems to work well as a mathematical metaphor and conceptual aid without a real world reference to what it is (excuse the existential reference) or how it is effected by mass or how it effects the paths of actual objects. The same can be said of the string/M-theory model... all model and no referents in 'the world' of 'empirical science'... the apparently obsolete branch of merely verified facts in the out of date "Big Book of Facts." How is physics different from metaphysics in the above cases? Darn! Another demerit! How can I gain personal popularity here and therefore make my arguments more cogent? (a little 'ad hominem' humor there.)... spelling edit.

("Ad hominem") Ad hominem literally means referring “to the man” rather than to the substance of the argument. It works both ways. Usually, of course it refers to “attacking an opponent's character rather than answering his argument.” (Dictionary.com) But it works both ways, as in referring to “a man’s” credentials to support his argument, regardless of its substance. This forum uses the above a lot. That's news to me. I thought that was the meaning of "empirical science." Swansont: The point is that the cosmos exists and has intrinsic properties regardless of how it is observed. But that is the philosophy of realism which does not concern those who believe that reality depends on how it is observed. I've made this point dozens of times, but it is still lost on you.

Back to this point for further clarification: The focus here is philosophy’s relevance to science. Since realism says (in a nutshell) that Earth is as it is, and idealism (specifically the length contraction theory version of idealism as I have explained in depth) says that Earth is as it is seen from different frames of reference... I will ask you again: Does an observation of Earth from a near lightspeed frame of reference, seeing it as quite flattened rather than almost spherical, mean that Earth IS actually very flattened or that it just looks that way, distorted by the extreme frame of reference? The well worn phrases from relativity, “for the high speed traveler” vs “for the at rest observer” refer to Earth having a different reality (shape in this case) depending on how it is viewed. So either Earth changes shape with how it is viewed (idealism) or we can not know what its shape is because of the “no preferred frame” dictum. Which is it? Ps; Still waiting for a reply to: Another edit: Cap ‘n R; post 101: Are you really saying that science is not concerned with which is the more accurate description of Earth?

TAR, post 107: Yes. Same for physics and for math in this regard. My Wiki quote from post 3 bears repeating (my bold): Ad hominem. Well, if the world is as it is independent of how we look at it, and it is science's job to get accurate info from observation of it, then a close up look at an object 'standing still' in front of us (at rest frame) will "see it" more "like it is" than flying by it at near light speed. Don't you agree? Science must design experiments and observational points of view to maximize accuracy of observation. No?

(My bold) The operative phrase here which distinguishes relativity’s form of idealism from realism is ...”for other observers.” My three examples in yesterday's post either are what they are, objectively, intrinsically and independent of observation, or they depend on observation and either vary as observed or they can not be known for certain, if all frames of reference yield equally valid results. Depending on how we look at it, Earth might be squished nearly flat “for me” (traveling past at high speed) and nearly spherical “for you” observing from the space station. How we see it determines reality in idealism, a philosophy assumed,however unconsciously*, by the length contraction part of relativity theory. But which will "agree with nature" best? *My opening quote from Daniel Dennett in this regard bears repeating: So, since science’s job is to investigate “the true nature of the world” (not just the nature of and differences between different observational perspectives), we must determine which of the above frames of reference yields the more accurate observations and measurements. This is a “no brainer.” Any competent scientist familiar with experimental design will agree. At rest with an object observed will always yield a more accurate analysis of the object that observation of it from a frame of reference flying by at near lightspeed, if that ever becomes possible. Edit regarding your: From my last post:

I thought we had established that there is no empirical evidence for large scale length contraction, though DrRocket said that an experiment to test it was planned. I simply wondered how the accelerator results transferred to the scales spoken of above. You did insist that the 'squished nearly flat' version of Earth's shape is just as valid as the familiar nearly spherical one, so the philosophy behind that extreme perspective seems very relevant to the theory of length contraction, i.e., is a case of how relevant philosophy (realism vs idealism) is to science. Do you really, truly deny that "...the distance to the Sun (remains) around 93 million miles, regardless of who is flying by at whatever speed measuring it?" This is clearly not the realism that grants the world an objective, intrinsic reality of its own, independent of observation and measurement. What if there were no observers, no measuring rods, no clocks? That is a philosophical question very relevant to science.

Swansont: Maybe the Cap 'n will find time to present my previous questions (about how the particle accelerator experiments both prove length contraction on micro scale and apply to larger scale phenomena) to his boss... as this is a science forum open to such questions. But he is probably busy and tired of my challenges. Hey, Cap 'n...! And the "correct information"... about the astronomical unit of distance and Earth's shape and the length of a meter relative to Earth's surface quadrant... is readily available on line and in science textbooks, and that info will in fact "put the lie" to your "length contracted" version of all of the above.

PeterJ: Better than OK. Free thinking is encouraged in philosophy, even in philosophy of science. Agreed up to ...”we can not ask...” The root of physics is science of the physical universe, not just theories in various minds, however genius, given names as concepts only with no referents in the cosmos. ("What is curved spacetime?... oh... a coordinate system... right.") This must be just a quick pass-by, but I appreciate not only what you said but what you did not say... like about the taboo word “consciousness”, which can not be uttered in a science forum, even in the philosophy section, without certain ridicule. (Lets not go there.) But what keeps distant particles (entangled) and distant cosmic objects (gravitationally attracted to each other), "in touch" so to speak, sharing "information" and bonded by forces, like gravity? Not introducing metaphysical speculation here. Just open to "what it is" as both information and force of attraction between all things. I am not expecting answers from today's science, materialistic as it must be.

Yes, the question is loaded with the ontological challenge that when relativity says that spacetime is curved by mass, something besides a concept in our minds is supposed to actually be curved and influence masses and light to follow that curvature. It is convenient for you to ignore the philosophy of science as applied to math and physics, but that does not make it irrellevant. Here again are the most relevant ontological questions about the "philosophical assumptions, foundations, and implications of mathematics" regarding spacetime (ref; Wiki): You can continue to ignore them but they will not go away. The "track" here at hand is a philosophical inquiry into the validity of relativity's claim that science either can not know the exact shape of Earth, or average distance to the Sun, or length of a meter rod, ... or that they vary with how they are observed and measured... all based on hypothetical theory which has never been verified empirically. ( Cap 'n R once invited me to ask questions of his boss on how the particle accelerator "confirmation" of length contraction applies to the above measurements. I asked a few, but there was no reply. And the reality of Earths atmospheric thickness according to muons really does not establish an alternative measure of same.) I will dig up my unanswered questions referenced above if you like.* And calling a challenge to length contraction a "lie" is just nonsense! The "lie" is that Earth is (or could be) so oblate that its diameter is about 1000 miles, as seen from a near light-speed fly-by. * I get that the particle accelerator results on length contraction are extremely complicated. I do question whether they show distance traveled by particles actually shortened (as applied to atmospheric muons) or whether they just "lived longer" than expected, prompting the claim for "time dilation." I can say with certainty based on realism that the distance between Earth and Sun does not vary with how it is observed.* The measurement from at rest on Earth (one end of the distance) is precise and well published in many astronomical websites and texts. The bodies can not and do not move closer together and further apart with every possible extreme in the frame of reference from which they might, hypothetically, be observed and measured. Belief that they do is delusional. (That is a professional opinion.) * Obviously it varies with Earth's position in its elliptical orbit. What statement was a "lie" exactly? I have answered your question about holes... the lack of the physical substance around them. Enough already. Is absence of something "real?" In so far as "absence" has meaning, yes. What is the meaning of something that doesn't exist but is curved by mass? See Wiki quotes above... and continue to ignore the questions, as always. "Run and hide??" You are the one ignoring the ontological questions here, assuming that "what it is" doesn't matter, but mass makes "it" curve anyway! How "convenient" to simply ignore what the dynamics might be... what mass makes into a curved "region" around the mass and how that non-existent curvature makes objects and light travel in curved paths! A "philosophy" (or hypothesis) that Earth may be squished nearly flat, because an extreme frame of reference might see it that way is definitely "wrong." If a patient walked into my office and claimed the above... well, I would at least refer him to the correct information from a few of those astronomy sites. (late spelling edit)

Pantheory quoting Einstein: ..."Time and space and gravitation have no separate existence from matter." I agree that without matter moving around through space, time would be meaningless. But we do have a difference on what space is (and, more to the point, is not.) Einstein said, to the same point as above, that if all matter vanished, there would be no time or space either. I think that if there were nothing in space, as above, there would only be empty space left. I have used the example of a small scale to illustrate. If all objects were removed from a box (ignoring air for the moment), the box would 'contain' nothing. It would be empty. (Empty space.)

Swansont: Me: Do you think that the concept of spacetime requires no referent in 'the real world' even though GR constantly claims that "IT" is curved by mass? "What is curved by mass?" is the ontological question here posed as "relevant to science." A concept is not curved by mass. Me: "Realism asserts..." You: "Yes, it asserts. But it either does not test this assertion to see if it is true, or it fails the test." This thread asks whether or not philosophy is relevant to science. Epistemology, how we know what we know, is not limited to empirical data, but also includes reason. It is reasonable to believe (and 'realism asserts') that Earth has a certain intrinsic shape in and of itself, independently of how it is observed and measured. A mountain of empirical data from Earth science verifies that shape as nearly spherical and specifies the difference between its polar and equatorial diameters. There is no evidence for a severely oblate shape of Earth as seen from hypothetical extreme frames of reference, as posited by length contraction. In my previous post I just summarized yet again for you the difference between the form of idealism which claims that reality (shape of Earth, length of a meter rod, and distance to the Sun, in this case) depends on how it is observed, from whatever frame of reference... and realism, which 'realizes' that the reality of the cosmos does not depend on how it is observed, but is as it is, intrinsically, and would be not different (except sans technology) if it were never observed and measured. Another way to say it, as I did yesterday is that "...the distance to the Sun would remain around 93 million miles, regardless of who is flying by at whatever speed measuring it." This is the philosophical difference between idealism and realism as applied to relativity's theory of length contraction. You: "At some point...?"... not to say "at this point" (transparent hedge) ...you are saying, "that's a lie"... not to say I am a liar??... but to whom other than me might you be referring as the one who "lied?" Doesn't a lie require a liar? I will leave it to an hypothetical jury to decide whether or not the intent of the above is to call me a liar, stripped of the transparent hedge. I simply answered, That would be, "yes, a hole really is the absence of the material around it."

pantheory: Matter. Space is obviously not empty where it is occupied by matter. "...volume designated between specified coordinates..." is not infinite, as the specified coordinates designate its boundaries. We agree, I think, that empty space is no-'thing'-ness between "things" (on all scales), and therefore is not a medium with malleable characteristics. "Nothing there" IS empty space. How could the "volume of all space which would be equal to the volume of the universe..." be finite? Again, what boundary do you propose that would make the universe, all space and all that is in it, finite? And beyond that... more space. What end? Please re-read my challenge of reason again on this point:

Pantheory and I disagree (I think) on whether or not space is infinite... see the Big Bang Theory thread in Speculations. Since that was going off topic I will continue my answer here, as it concerns the ontological (philosophical) question, "What is space?" Some of us hammered on this question already in at least two threads: "If there is no end to space" in the Astronomy and Cosmology section and "Infinite Space" in the Relativity section. To very briefly summarize my argument on that, I "invoke" the a-priori reason branch of epistemology and ask you to consider what an "end of space" would be and describe it. What would be on the "other side" of that proposed end of space. Infinity means, in this case, "no end" or "not finite." Whoever proposes an end defining "finite space" must describe what that 'boundary' or whatever IS... in the ontological sense.

Agreed. No intention to "hijack" this thread. I suggest my "Is philosophy relevant to science?" thread in philosophy, where "What does infinite space mean?" will be an on topic question.

How is space an "extension of matter" rather than just the absence of it? Yes.

Ever since Minkowski came up with 'spacetime' and Einstein made it the (whatever) curved by mass to explain how gravity makes matter and light travel in curved paths, all explanations of general relativity refer to the curvature of spacetime. To what part of "malleable mystery medium" do you object? If mass makes 'it' curve, 'it' must be malleable. If no one knows "what it IS," 'it' is mysterious. What noun besides "medium" do you prefer? If 'it' is just a concept in a coordinate system, then to what does the concept refer in the cosmos which the theory attempts to describe? I argue that the "length contraction" part of relativity is based on a form of idealism which says that the length of a rod, the distance to the Sun and even the shape of Earth are not intrinsic properties of those objects and the distance between them (in the case of the Au), but rather they all depend on the frame of reference from which they are observed and measured. Realism asserts that 'the world' (cosmos and all its parts) exists and has intrinsic properties independent of how they are observed/measured... that if intelligent observers never evolved, cosmos would be the same (less our technology)... and the distance to the Sun would remain around 93 million miles, regardless of who is flying by at whatever speed measuring it... etc. for the other two examples. There is 'a world of difference' between the two philosophies. Yet you present realism as not only merely my personal point of view, but a "lie"... calling me a liar in the process. As to "Who are you...?," again, it is not about 'me' as you keep insisting. You continually insist on personally attacking me rather than discussing the substance of my arguments. If you are an expert in what a "strawman argument" is, as you claim, you know that this is a bogus and completely irrelevant argument. I have presented (many times) the ontological argument that space is simply the emptiness, the volume or distance, between particles/objects, both subatomic and on cosmic scale. "It" is not a "thing" that has shape/curvature or the ability to expand. So ontology examines "what it IS" (or is not) in each case. Yes, a hole is the absence of the material around it, and space is the absence of material in between things on all scales. Now, back to some of the questions I asked before T-day... What IS a dimension... etc... anyone? What direction does even one "extra dimension" signify after the three known directions? Or is "What do we mean by 'extra dimensions'", not a question relevant to the "scientific" theories which employ them?