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Tar, Here is the Wikipedia link to presentism: http://en.wikipedia.org/wiki/Presentism_%28philosophy_of_time%29 It contrasts the well known “light cone” concept of relativity to a very common sense version of time, with which I agree. As I've argued repeatedly in this thread (and it seems absolutely obvious to me), the past is dead and gone, and the future is not yet present (duh!) Time is not such an entity as the "light cone" or spacetime concept assumes. The "block universe" has everything that has ever existed and everything that will ever exist as "real" and dependiing only on point of view from individual points of perception in each possible "light cone." In contrast, one version of presentism (with which I agree) asserts that now is ongoing, everywhere, i.e., that the present is present everywhere, that there are not an infinite number of "time environments" as in the "light cone" model. Philosophically this perspective transcends relativity's focus on (and obsession with, I would say) what frame of reference sees what images (or gets what information) from where and when. In other words this version of presentism does not take the speed limit of light and resulting "signal delay" to be the ultimate limit and ontological absolute for what is real and existing in the present in the whole universe. Relativity can not be denied for for what it covers (leaving length contraction and time dilation out of it for now.) Once we get over the reification of time as an entity (see my argument for time as only event duration for physical processes, EDPP) we can begin to see that the present is omni-present. We must begin by realizing that "is" means now... the present, and there are no local "time environments" for each supposed "point in spacetime" at the apex of each imaginary "light cone."

First, You did not clarify the apparent contradiction detailed in my post 16 above. Is it not a legitimate concern of physics to have a consensual understanding of such a core and fundamental element of relativity as spacetime, since the claim is that gravity morphs "it" without any clarity on what "it" is? What do you think all the fuss is about (conferences, papers, hot debate) over the last decade on spacetime ontology? You can continue to ignore it but it is not about to go away. From the conclusion of the Ross paper linked above: Back to the length contraction issue as it pertains to subjective vs objective, again from md's Wikipedia link on conventionalism above: The above denies an “objective universe” in which things and the relationships between them exist independently of observation/measurement. Rather it asserts that everything is relative to to the frame of reference from which it is observed, length contraction being the immediate case in point. So, when the two rods of equal length ( as observed side by side) are separated and one appears shorter than the other (length contracted), the philosophy of subjective idealism (substituting frame of reference for subject) prevails. This philosophy claims that one rod magically actually gets shorter when so observed/measured, and then, when both are brought back together again, the “shorter” one is magically restored to its previous longer length, now the same length as the other rod. This makes length contraction no different in principle than a stage magic trick (illusion) of perception. Same for the perception of earth as flattened in the direction of movement of the often belabored high speed frame of reference. If we agree (big "if," it seems) that earth does not actually deform from spherical, then that leaves the length contracted perspective/measurement in error, one would assume due to the relativistic effect.

Shall we have a dialogue consisting of questions in reply to questions? With “it” as spacetime ontology, how could we test to verify spacetime as an existing entity without which gravity would not work? Can we experimentally verify that gravity does not work without spacetime? Or is the “fabric of spacetime” that material of which the Emporer’s New Clothes are made? If only physicists fluent in math can "see" spacetime, does that make the rest of us stupid and unsophisticated, or simply childlike and in need of higher education in math/physics?

?????? Clarification needed. me: Cap ‘n R: me: Cap 'n R: I get your repeated statements that the flattening (length contraction) as seen/measured from a near 'C' fly-by frame of reference does not involve any mysterious force crushing earth out of its nearly spherical shape... but... Are you saying that we do or do not know that earth does not actually flatten out? In your first quote above you "do not" deny the common knowledge "that earth never actually flattens out." Then, immediately above, you do deny the same. Very confusing. On spacetime ontology; me: Cap ‘n R: Knowing the nature of what it is that physics claims as something(?) that guides moving objects is not a subject of relevance to physics?? If "it" has "grooves or ruts," what is it that has grooves or ruts? How can this not be relevant? If "it" is not that substantial, what is it anyway?... a return of the "luminiferous aether" or what... a metaphysical concept without being any kind of entity in the "real world?" Why does gravity require "spacetime" as a medium by which objects are guided, like into orbits around stars or whatever?

So you use the word spacetime like it was an established reality and comfortably ignore all the debate on what the heck it actually is. Ok, there can be no conversation on it in that case. If you look at my near-last entry in the spacetime ontology thread you will see some discussion of the possibility of "grooves or ruts" in spacetime which guide objects in their movements. Do you ever wonder what kind of 'whatever'... substance, entity, ether, medium... this "fabric of spacetime" actually is, as something (?) which guides moving objects? This is the focus of the International Society for the Advanced Study of Spacetime (ISASS), and it is a legitimate sub-field of the philosophy of science as relevant to relativity. To my : ... you answered, "No, we don't. How could we?" We "know" through earth science that earth is not like malleable silly-putty; rather that it is a relatively rigid, near spherical object,... that earth never actually flattens out as the above extreme frame of reference "sees" it. Do you deny that we know the above about earth? I know the difference between classical subjective idealism and positivism which you have distinguished above. My argument is that frame of reference is like the subjective perspective in idealism in that relativity claims that high speed fly-by frames are equally as accurate as frames at rest with what is measured; which yield the absurdities of a flattened earth and an extremely short astronomical unit as "just as real" as the actual shape of earth and actual distance to the sun (as measured from at rest frames.) Relativity theorists here have said that "for a photon" there is no distance and no travel time between sun and earth. Yet we know that 'C' is constant in space and that it takes 8+ minutes for sunlight to reach earth. But no intelligent person will say that there is no distance between earth and sun, just because the "photon's perspective" is just as real as actual travel time and distance traveled by sunlight. You defined positivism above as: We can know from earth science that earth is not malleable enough to squish or flatten, so we can know that such "length contracted" measurement is due a distortion effect of the near light speed frame using light as the medium carrying the image. And philosophically, as in a-priori epistemology, we know that the tree falling in the forest makes "real" sound waves in the air whether we hear and measure them or not. I'm on the run again, but... I've read a lot of Deiks' edited volumes of papers from the ISASS without taking notes to support my argument. The last reference to spacetime as a medium with "ruts and grooves" for guiding objects (in my spacetime ontology thread) was, I think, from the paper on Minkowski's spacetime; a glorious non-entity. (Brown and Pooley) You mentioned the jump to non-Euclidean geometry in another post. Here is my often posted link to Kelley Ross's paper, The Ontology and Cosmology of Non-Euclidean Geometry: http://www.friesian.com/curved-1.htm Thanks for your Wikipedia link on conventionalism. I just have time for a brief comment on the following: If the universe is “objective” in the sense that reality is as it is, independent of local frames of reference from which distances are measured, then it doesn’t matter what you call the actual space (distance) between objects (through which light travels at constant velocity)... “absolute space” or whatever..., and whatever label for that space/distance like “luminiferous ether” is irrelevant . It stays the same no matter how or from where or at what velocity it is measured. Relativity takes into account these SR effects and yields useful and very well documented results... none of which make actual distances between objects, or sizes or shapes of objects vary with extremes of frames of reference from which they are measured. If extreme frames of reference in measurement were equal and "just as real" criteria for describing the universe as at rest frames of reference, then relativity would be very similar to subjective idealism in that one subject's perspective would be just as accurate as another's... like how loud was the sound of the falling tree, from miles away as contrasted with right under it... the last sound the person with "accurate perception" heard! But we have a formula, as does relativity, for knowing the actual decibel level at the tree, even from far away, if we know exactly how far. I'll find specific ontology links if you want, as requested, but first, please read those cited in my "Spacetime Onbtology: the Scholarly Debate" thread. I had barely begun to cite references for discussion there when it went off on a specific tangent.

I am very interested in your perspective on the ontology of spacetime as referenced in my thread on the subject. I am also very interested in your relies to the specific points made in my opening post on frames of reference as "subject" in subjective idealism. For instance, don't we we all know that earth does not actually flatten out (in the direction of motion) as seen/measured from a near 'C' fly-by frame of reference? Gotta go.

First, "spacetime" is the subject of a lot of debate in the philosophy of science community. Please check out my old thread (here in the Philosophy section) on Spacetime Ontology, the Scholarly Debate, specifically the volumes of papers from the International Society for the Advanced Study of Spacetime conferences. I understand 3-D space plus the time factor, as things move around in space, which "takes time." But it seems to me that you move from the "objective" ("immutable") universe into the "subjective" realm of mental concepts without objective referents when you start slicing up a debatable 4-D "spacetime" and viewing "different three-dimensional sections out of the four-dimensional (immutable) whole." In what I am calling the objective world we can focus on a specific volume ("section?") of 3-D space and observe whatever is moving around in that space and measure the elapsed time as an object moves from A to B, and that looks to me like solid empirical science. But once you speak of "spacetime" and sliced up sections of it, you have introduced a debatable element and entered the conceptual, mental, metaphorical realm of "slicing" 4-D spacetime (like your loaf of raisin bread in the other thread.) It seems like a thought experiment without objective referents "in the real world" to me (ontologically speaking, of course.) Ps: I'm gone 'til Mon.

pantheory: Ask the physicists here, but compacting of molecules under extreme acceleration is not what the relativity measurement effect called length contraction is about... as I understand it. I know that a bullet gets a bit shorter (and fatter) when fired from a gun. But that is not what "they" mean by length contraction. Editing to box the quote. Better clarity.

I will reply in my new thread on the philosophical basis of relativity's assertion that all frames of reference yield equally valid measurements. (Just info for the interested... a small plug.) (philosophy section, yet another ontology thread.)

The point of departure for this thread comes from my comments in the Ontology of Time thread in the Speculations section about the insistence in relativity that there are no "preferred" frames of reference, no "correct" or "objective" measurements when comparing one frame of reference (FOR) to another. From post 182, 7/2 in that thread: So, applying the above argument to "length contraction," if there is no objective "reality" independent of various FORs, then as discussed at length in the former thread, the distance between earth and sun varies with FOR, shortening radically with high speed fly-by FORs, for instance. Likewise, earth itself, measured as above, is flattened in the direction of the motion from which it is measured. My argument then as now is that one astronomical unit stays the same length and earth stays the same shape and size, in the objective world of what is, independent of extreme platforms (FORs) from which they are measured. To claim otherwise, i.e., that "there is no preferred FOR... those measurements are equally correct" means that one perspective is just as accurate as another, and therefore, there is no objective universe. It all depends on how we look at (and measure) it. So, accordingly the "at rest" frame with what is being measured will be the accurate FOR and yield the actual size and shape and distance between objects (measured from one of the end points.) I know this is relativity "heresy" but I believe it is sound philosophy of science. It is not an attempt to "debunk relativity" but to bring clarity to the confused subjective idealism of relativity regarding FOR as "subject." I'll leave it there for now and open it up for discussion.

Ontology is the study "of that which is" (Wikipedia), i.e., what "exists," its nature as an entity (or not), whether as a concept only (like event duration) or existing independently, on its own, as a naturally occurring object or process, etc. The application of ontology to time, therefore, must examine "what dilates" and what dilation means when we say (usually automatically, without a second thought to such considerations), "time dilation." That has been my intended focus in this thread. Often times it seems that "time dilation" is taken to mean that time is an entity, an environment of some kind that surrounds moving objects or objects in different gravity fields and expands or contracts with those fields or velocities. My ontology and coinage of "EDPP" is simply an attempt to demystify such references to time in relativity theory. All of the above also applies to the use of the phrase "length contraction" in relativity, though not specifically the topic here. Ontologically speaking wide variations in measurement at high speeds (from different frames of reference) does not mean that objects and distances/lengths being measured actually shrink (or deform) and expand as so measured. I will start a new thread in the philosophy section to discuss this and how the philosophy of subjective idealism applies to such frame of reference variation and to discuss more generally objective vs subjective perspectives on "reality."

TAR2: Relativity has shown (and I accept) that clocks at high speed "tick" slower. I assume that all physical processes including the human aging process "proceed" more slowly at high speed. (This does not mean that some undefined thing, "time" "dilates," whatever that means besides clocks ticking slower... the focal point of this thread.) So, if a space ship with the most accurate possible clock on board, and its voyagers go on a near 'C' round trip from earth and back, and their slowed down clock shows that only five years have elapsed (and they show only five years of aging), ... and meanwhile earth has orbited sun ten times, I maintain that "in the real world" ten years have passed. Maybe it makes no difference whether we say that "time has dilated" for the voyagers. But the above explanation does not require that "time" be "something that dilates." We can stick to what we observe and just say that high speed makes the spaceship's clock slow down as well as the passengers' aging process. Its about "the ontology of time." swansont: Of course "clocks can tick slower for a multitude of reasons that do not include time dilation..." They can also slow down because they are traveling at high velocity, as above, without "making something" malleable out of time. But I see you prefer to return to name calling rather than addressing the latter point. I've said dozens of times that I do not deny the above observed effects of relativity (including also clocks in different gravitational environments.) Your smear tactic of calling my argument a "relativity denial complex... in misplaced hopes of overturning relativity theory"... ignores all of the above yet again.

TAR2: Absolutely. The whole universe is not about who can see what from where and when as limited by light-speed. Presentism. Now IS everywhere, not an infinite variety of local "time environments" throughout the universe. . I think we all agree that the near ‘C’ fly-by perspective will get a different earth (or AU) measure than the at- rest frame on earth or from orbiting satellites. I simply insist that the at- rest frame is accurate, and that earth does not “actually” shrink or get squished/ flattened out-of round (or the AU shorten to 1/8th) as so measured (and taken as“equally correct.”) Understood and agreed. Here again is my argument on time ontology relative “the year” and high speed measures of it: The time it takes for one earth orbit does not change (much) in the “real, objective universe” (if I may be so bold) regardless of how space voyagers measure time, say, as previously, on a 10 earth year round trip. They record 5 years elapsed time, and have only “aged” 5 years while all of us here on earth have meanwhile recorded and aged 10 years. High speed slows down physical processes, both clocks' ticking and probably the aging process. I have many times agreed that relativity has the correct formulae for such “transformation” of measurements, so that we all end up “on the same page”... and keep GPS positioning accurate, etc. swansont. I understand, up to the semicolon. But how is, “time slows down...” different than “clocks tick slower”... the observable physical process which claims a longer “event duration” (dilated time?) Ps: I would like to return to the argument, for a moment, against relativity's claim that all measurements, as above, are equally correct. I suggested that this claim puts relativity squarely in subscription to the subjective idealism philosophy. (See Berkeley and Hume, the most well known proponents.) I reiterated the old cliche' about the tree falling in the forest (see above recent post.) The falling tree makes sound waves whether heard and measured or not. I call this real objective nature in this case, independent of perception and measurement. And, to the finer point, measuring the decibel level of that sound from further away, resulting in lower sound level, does not mean that the sound level at the falling tree diminishes. (The recorded decibel level diminishes with the square of the distance.) Again, the accurate measure of sound level is at the falling tree, and, we can adjust for further distances and quieter sound levels with the 'square of the distance' formula and not claim that the quieter measure is "equally accurate." This is philosophy as relevant to physics.

Swansont: How do you see the difference, in meaningful language, between expansion and dilation?

I agree that "We're limited to what can be empirically observed..." That's why I suggested EDPP as an observable, meaningful substitute phrase for "time." Physical processes are, of course, (mostly) observable and their duration can be measured by clocks. But when a process slows down (whether the rate of a clock's ticking or the aging process of high speed space voyagers) and we say, "therefore time dilates," we introduce an unobservable element, the expansion of "time," the nature of which is still in a state of hot ontological debate (not just in this thread.) This would seem like a clear improvement in the way we communicate about time, which is one reason that ontology is relevant to physics in this case. swansont: You are right that my original comments about time were in another thread which I didn't originate. I think it is harsh to call it a hijack of that thread, however, because the thread was addressing the nature of time. It was just a question of protocol in that regard, but now, of course, I wish I had started this thread in philosophy. I don't think it is "wrong" to distinguish the observable slowing of physical processes (including clocks' ticking), for instance at high speeds or altered gravitational fields, from the assertion that "time dilates," as explained above.

Back later with a full reply. Just a quick reply to your last statement: That is why this thread belongs in the philosophy of science department as the ontological inquiry it is. I've asked and practically begged, just because it is what it is, ontology. "Thanks" for nothing. Even saying "How time behaves..." assumes that everyone already knows what time is! "It" doesn't "behave" at all if it is, as I've argued simply the event duration of physical processes. They "behave" by slowing down and speeding up in various environments. That does not make time something which expands (dilates.) That, however is about the ontology of time... the subject of this thread, if reminders are required.

The following basic question has not been answered, and it is the take-off point for non-Euclidean geometry. From post 166: Or, in a nutshell, what about extending parallel lines “far enough” makes them converge and intersect? (Ontology.) Then, regarding a mini-earth as equally accurate with what I am calling the real, full sized earth: Cap ‘, R: How is this different from the philosophy of subjective idealism (applied to relativity), as I asked before, referencing Berkeley and Hume? Summary: There is no objective reality independent of perception/measurement from different reference frames. Perception/measurement creates reality. An aside for illustration: (Cliche' ref): "If a tree falls in the forest and no one hears it, does it make a sound?" Of course it makes sound waves in the air whether or not they strike human ears. And the actual at- site decibel level will not change with various distances from the tree from which it is measured.) This is where ontology as part of the philosophy of science is absolutely relevant to the questions at hand. A mini-earth of diameter 1/8 th “actual size” is just as correct as the size of the earth we all know and love? I really can’t imagine a more absurd assertion calling itself science. Regarding the previous conversation about whether length contraction applies to objects in the macro-world (beyond the subatomic results from particle accelerators): DrRocket said that a planned experiment on the above has not yet been done. Is your statement above based on faith alone or experimental evidence not yet published? I hope you don’t actually believe that Euclidean geometry is confined to 2-D planes. So why dismiss it as if it were so confined? Actually, one faction in non-Euclidean geometry does assert this mystery forth spatial dimension. Yet it remains a concept without a referent in the “universe.” I have no problem with 3-Space plus time as the movement factor as “it takes time” for stuff to move around in 3-D space. Then there is malleable spacetime (as a math/physics *concept*) with time and space combining into something that gravity curves... that without a definitive answer to what either or both combined is in the first place. (Ontology. See reference sources earlier in the thread.)

swansont: Lines that intersect are not parallel lines. Non-Euclidean geometry "re-invents" the meaning of parallel. Lines drawn on a sphere and intersecting at the poles (longitudinal lines) are not "parallel at the equator." They are widest apart at the equator and steadily converge until they intersect at the poles. You might try actually reading Ross's paper on the Ontology and Cosmology of Non-Euclidean Geometry. The focus of this thread is, after all the ontology of time as an aspect of the ontology of relativity. Cap ,n R; Parallel lines, by definition, do not intersect. Non-Euclidean geometry "re-invents" the definition of parallel lines... which was my point above as to who is re-inventing what in reply to your "inventing" comment. Ontology is the inquiry into what exists in the real world, not just in the minds of mathematicians/physicists. I asked you, for instance, to explain what a fourth spatial dimension is in the real world, since the three axes of 3-space already have volume covered... a line being one dimensional, a plane being two dimensional, and volume (my understanding of space, being three dimensional. Ontology asks what referent a "fourth spatial dimension" has in the real world. You refuse to answer or explain. Math is not the explanation. Ross covers this in detail. Have you read him? As above, what is the evidence for a forth spatial dimension. Again (and again)... so which is the correct measurement of earth: the 1589 million km diameter mini-earth or the 12713 million km diameter earth, if "all frames of reference are equally good. Do you think that there is any possibility that flying by at near light speed and depending on light to convey the image of earth might possibly distort the image to a 1589 million km diameter earth, or do you insist that the very small earth is an equally correct determination of earth's size. This is a valid ontological question. I am asking for a clear and straight forward answer. Same for the diminished distance between earth and sun and the obvious catastrophic consequences of a 1/8 AU distance, if "equally valid." Your extensive math/physics reply totally avoided the ontological questions I keep raising here. The extensive equations you worked up do not address the reality questions above. The math does not address the meaning.

The reason I was trying to get you and the forum to read the ontology sources referenced above is because they do often focus on what seems "invented" about time, space, and spacetime since the non-Euclidean revolution in physics (and geometry and cosmology.) For instance the fundamental departure from Euclidean geometry was based on tossing out his fifth postulate on parallel lines. Can anyone here explain what it means to say that parallel lines do eventually intersect "in infinity?" I get that math can easily deal with the latter, but how is it that if those lines are extended far enough (to "infinity") that they do actually intersect (at which point they are no longer parallel lines, by definition?) Maybe just a baby step at a time as above will get the focus back on ontology here. Then maybe someone will eventually answer how relativity convinces folks that a 1589 million km (1/8 the established figure) measure of earth's diameter, as measured from the near 'C' fly-by frame of reference, the "mini-earth" above is just as accurate as the well established 12756 million km polar diameter. I just can't believe that anyone thinks earth shrinks to accommodate the "accuracy" of such a measure. If it does not, then the 12756 million km diameter is accurate, and the 1589 million km is in error.

Cap 'n R: Yes. More like the impossibility of "visualizing" a fourth spatial dimension, since three axes fully describe "space" as a 3-D matrix. (What direction is signified by a fourth axis?... not "time" as a fourth spatial dimension.)) This will make little sense until you understand the ontological debate about space and time. I have provided links (many times) to the ontology of the spacetime debate. Little response. The International Society for the Advanced Study of Spacetime has presented many scientific/philosophical papers on the subject over the last decade of conferences on the subject. Mostly ignored as I have presented links in this forum. I suggested that you read my favorite author on this Euclidean/ non-Euclidean debate, (as pertains to relativity) but you have not commented on the paper linked above. Too busy to read new information? I don't know. Just guessing. You must be busy as a science website administrator. Please put this thread in the philosophy section where it can be formally ignored by physicists who don't care about the ontology of time.. or space.. or "spacetime." Thanks.

me: Cap ‘n R: Is this a snub from the assumption that math trumps conceptual understanding (ontology) and requires no explanation as to how it explains astronomical distances... and their thermodynamic and gravitational ... and mini-sized earth... consequences? Are you consciously ignoring my statement above and just assuming that math is superior to ontology in the overall perspective and that the subject of the thread is irrelevant and subservient to the magical math/physics you just presented? These are honest and sincere questions from my 'frame of reference.' Please answer as honestly as you can. I will study your reply in depth when I have "time", but you can not be seriously implying that relativity is the scientific version of subjective idealism* (see Hume and Berkeley) with the “subject” being “frame of reference”, by which everything shrinks and expands with high speed platforms of measurement. *...Most briefly, that REALITY depends on perception/perspective, with no existence in and of itself (the objective cosmos which for which I always argue.) But of course this is philosophy of science... wrong section... and no one yet will put the thread where it belongs.

Cap ‘n R: (my bold) Yes, and especially the magical math of physics, quite literally it seems! So how does all that math/physics address the (excuse the phrase) reality of the situation as expressed in your statement above: In other words, on the one hand you seem to agree that earth does not actually move closer to the sun, as length contracted measurements would have it. On the other hand, all that physics seems to be an argument for the opposite, i.e., that the 19 million km distance, as seen from the fly-by frame is accurate in ‘the real world’ and that, by the above “magic” somehow the heat diminishes with the shorter distance and time of exposure. Again, I do not deny that the voyager “will see the earth as being closer to the sun.” But it still looks like a distortion effect of relativity to me. Same with earth’s diameter. It does not shrink just because extremely high speed frames of reference from which it is measured make it look like a 1/8 sized mini-earth. As admitted many times, I do not understand the advanced math, but I do understand the concepts of closer vs further away and that, in reality, the closer anyone (or anything) gets to the sun, or any other star (or hot object) the hotter it gets. It seems to me (and, I would argue, from the ontological perspective, inquiring into what is real here) that the complex physics in this case is mental magic, smoke and mirrors of the mind, for the reasons just stated. Ps: What did you think of Ross's ontology (if you read it) as an analysis of how non-Euclidean geometry (as basic to relativity) developed?

Which of these statements is true: Earth is 19 million km from sun... or Earth is 150 million km from sun? Clearly the latter, as posted on all astronomy sites that give distances between bodies in our solar system. The near ‘C’ fly -by measures the former because of the relativity effect (distortion), but that does not mean earth is actually 19 million miles from the sun during the fly-by. As I said in post 107 "We would fry if we got that much closer to our sun. It simply is not true. Measurement does not make the distance change!” I asked, to no avail, how perspective makes the distance change, and if it changed to 1/8 AU (19 million km) why would we not fry? We don’t fry because the actual distance remains 150 million km from the sun and the former is a distortion due to the effects of relativity. Likewise Earth obviously does not shrink when a similar fly-by measures the diameter as one eight of what we measure from satellites at rest with earth. To claim that it does shrink or that the AU shrinks because relativity promotes length contraction and insists that there is no preferred frame of reference... so near ‘C’ fly by frames are just as accurate as at rest frames in either case is simply nonsense. Earth does not get closer to sun because relativity insists on length contraction and the dictum, "no preferred frame of reference." In post 141 Cap ‘n R said: So what he sees is distorted, i.e., earth is not actually closer to the sun just because that is how he sees it. Cap ;n R: How would they account for the fact that they are not fried by such close proximity if the shorter measurement is not just a distortion. It remains a hot ball of fire not just a concept. You did not answer my question: (“Your perspective makes the distance change? Again, how is that different from measurement.”)... with your question. I agree that there is no way to tell.... unlike all the sophisticated measurements of Earth and our solar system from at rest frames relative to what is measured.... and the lack of shrinkage, as above with every supposed length contracted measure. As a matter of practical application, say for placing a satellite close to the sun, the preferred frame to measure the distance (and not let the satellite burn up) will not be the one that gets 19 million km for earth’s distance from it, but the standard as measured from earth (at rest at an end point of the distance measured.) md65536: Yes you got my meaning wrong. Event duration is from one instant to another, regardless of what arbitrary units of time we apply to this “elapsed time.” Physical processes in nature, on all scales and in clocks of all kinds proceed at various rates in different environments. When a clock slows down and we say “time dilates” it reifies time. The observable event is simply that a clock slows down, say at high speed or in altered gravitational field. My EDPP simply refers to time as the observed event duration of any physical process... which avoids “making something of time” as something that expands around objects as above. swansont: Yes I have, quite a few times, and again above. If 19 million km were the correct distance from sun to earth (as above) we would all be fried. If earth’s diameter were 1589 km (1/8 actual diameter) rather than the precisely measured 12713 km (pole to pole)... well... it wouldn’t be Earth anymore, would it?

swansont: What am I missing here? If the 1/8 AU measurement were correct, earth would be about 19 million km from the sun rather than 150 million (one AU), the at -rest measurement, but it isn’t. Why does this fact require a new “physics test” to establish its validity? No astronomer in the world will scratch his head and wonder, "Is earth 19 million km from the sun or 150 million?" The latter is correct, and all astronomers know it without devising novel physics tests to prove it. md65536: There is no need to belabor the point that a moving frame of reference results in a shorter measurement than the at rest one. Not disputed. I repeat: The meter was derived as an earth- commensurate standard of measure, being one ten millionth of earth’s surface distance from equator to pole. I contend (and am certain) that neither the length of the meter nor the size of the earth are changed by measurements made from moving frames of reference. swansont: DrRocket, post 106: I will be as interested as anyone else if/when the results of the planned experiment are in. Anticipating such positive results do not count as support for length contraction in the macro-world. I am not disputing the effects of high speed frames of reference on measurement. I call it a distortion when such a measurement yields a small fraction of the known distance to the sun or earth diameter. It is a very good thing that relativity can make adjustments as needed for navigation, GPS accuracy, astronomical measurements, etc. Ontologically speaking (as per thread topic), the well established evidence that "They live longer when moving fast” (both muons and probably space travelers) does not equate to “time dilates” or expands around them on their journey. Astronauts and muons aging more slowly and living longer and clocks ticking slower are physical processes that slow down with higher velocity. (No dispute.) This does not make time something that expands (which dilation means.) Likewise, traveling further than expected does not equate to length traveled contracting... both points being the primary focus of ontology in this thread. Ps; I'm still looking for clarification of this statement by Cap 'n R (post 107): Your perspective makes the distance change? Again, how is that different from measurement. How is it that a 1/8 AU (19 or 21..?.. million km measurement or perspective (?) of sun-earth distance is not a distortion due to the relativistic effects of super high velocity?

Cap ‘n R, Please help me sort this out: Me: You: Obviously, as I have been insisting. So this answers, for me, the question, “Who is right: the whole population of earth, the at- rest frame of reference at one end of the length/distance in question, measuring the standard one AU, or the voyager traveling at near ‘C’ and measuring the distance as 1/8 th AU? And I must repeat the “reality check” that if the distance was “actually” 1/8 AU, we would all fry as increased gravity crushes the earth. I am left wondering how anyone can claim that both measurements are equally correct just because of the relentless dictum of relativity that there are no preferred frames of reference. The same argument applies, of course, to the meter stick (in hand, at rest frame) staying one meter long even while the near ‘C’ fly-by guy measures it as a tenth (or an eighth) of a meter. As to your loaf of raisin bread: First, a plane is two dimensional and volume (space or a loaf of bread) is three-dimensional. Imagining otherwise, for me is like imagining unicorns. I can do it, but that does not make them "actually" exist. Four dimensional space is nonsense to my (I think rational) mind. The three axes of 3-D space describe volume, and a fourth would be nonsense... no fourth dimension to space. Time, of course is a factor, usually called a “dimension,” but it just refers to “elapsed time” as objects move through 3-D space from A to B. I have frequently quoted from Kelley Ross’s paper on that subject. If you have not yet read it, you might find it interesting, as it speaks directly to these dimensional shifts in thinking and how/if they apply to “the real world.” You will find his The Ontology and Cosmology of Non-Euclidean Geometry at: http://www.friesian.com/curved-1.htm And while you are at it (as space and time are so intertwined in physics)... please also focus on Ross’s analysis of intrinsic vs extrinsic curvature as it relates to different *conceptual* manifolds. This is where non-Euclidean “curved space” came from in the first place, summarized briefly as follows: A curved line creates (requires) a plane; A curved surface (no longer a plane) creates (requires) volume; A supposed “curved volume or space” must, therefore create (require) a fourth spatial dimension. But now it becomes a mental concept without a referent, as we have run out of spatial dimensions with 3-D space. The ontology of such dimensions as in your loaf metaphor is, of course, a deep study... and I have often criticized "extra dimensions" beyond 3-D as metaphysical or imaginary... like the 7 extra ones in M-Theory (beyond 3-space + time.) What I like about ontology is that it questions things like "time" and "space" rather than taking them for granted as presented in textbooks... Like: "spacetime is curved by gravity"... assuming the components as taught in school ever since Minkowski and Einstein made the concept integral ingredients in relativity theory.