owl

Well, my theory is that, anywhere in the universe, the most accurate description/measurements of any object (or distance between objects) will be from the at rest frame relative to the object or distance described/measured. This seems like an unnecessary repeat, but I think the theory is verified by both kinds of epistemology mentioned in my "theory of common sense" post above. For one thing, length contraction on large scale has never been experimentally verified. (Also mentioned above.) Further, earth can not be both spheroid and radically flattened, so one shape must be true and the other false (or say a distorted image.) My money is on the spheroid for all the reasons recently argued. If we defined length contraction as the distorted optical image of objects due to the extreme frame of reference of flying by at near light speed and yet depending on light to convey the image... there would be no dispute here. But consider again the high speed voyagers flying by, seeing earth as squished at the poles... then (second pass) squished at the equator, and then, from orbit (at rest frame) as nearly spherical. Say they are on a mission to report the shapes of bodies in our solar system. What will they report? That earth changes with the three frames above? No. All agree that it does not radically change shape. So what will they report as good objective scientists? To the last challenge: I keeping with all of the above,... If dwellers near galactic center want to know earth's shape, they had best come close, preferably into earth orbit and find out without all those high speed (and long distance) image distortions. Say the voyagers above were on such a mission. I'm betting they reported a nearly spherical earth.

Swansont: I will be glad to if I can find out if I did in fact make a false accusation. This will require a detailed review of the posts in question. Here goes. (Bold added) my post 55 : I agree that I did not (obviously) ask specifically "What is spacetime?" in the above post. swansont post 56: “GR does” how with spacetime curved as compared to without curved spacetime? Not answered. me in 57: “Swansont lists the most often quoted successes of relativity theory above without addressing exactly how "spacetime" is a necessary element. my repeat quote in post 57: swansont in post 59: Again, you answered that "GR does", not how curved spacetime is essential to how it does. me in 64: Here, the question in dispute, "what IS spacetime" appears as an "in other words" to clarify the repeated question above it, which you still have not answered. Ontologically, if one claims that spacetime curvature is essential to those quoted successes of GR, it would be essential to establish what spacetime IS, as "it" manifests the property of curvature. swansont post 65: So our spatiotemporal coordinates get warped, as distinguished from an existing malleable medium getting warped by mass? Is that kind of a mind warp or what?... (a little humor, very little maybe, but essentially an honest question.) ...mass and energy warp what?... the essential ontological question presented in this thread. swansont, post 65: Got it. It was a later "in other words" to clarify my question in post 55. Should I apologize for the attempt at clarification. OK, sorry. Now, do you want to continue to whip me over our differences in the significance of the above dispute (a technical detail point for you as I see it) or are you interested in addressing the thread topic, starting with the unanswered questions immediately above?

My argument that earth is in fact nearly spherical and not squished nearly flat (as the disputed frame of reference would have it) is based on a lot of earth science and common experience among earthlings since the "flat earth" era before science knew anything about earth's shape. And now we have the beautiful view of a spherical earth from space. Even epistemology (how we know what we know) confirms this knowledge from not only the above mountain of empirical evidence (a-posteriori) but from reason* itself (a-priori.) *(That earth can not possibly be both spherical and radically flattened in Reality, regardless of extreme claims from extreme frames with clearly distorted images of earth.) So, along come the famous thought experiments extrapolated from sub-atomic physics (in particle accelerators) trying to apply length contraction to the larger world, unsuccessfully so far. One of your fav's is the near 'C' travelers for whom earth IS nearly squished flat... not just "appears" that way. I have appealed to the obvious absurdity of believing that earth is actually squished out of spherical, to no avail. I have said it can not be (objectively speaking) both spherical and squished, so it must "actually, objectively" be one or the other... to no avail. I give up. Believe what you (and length contraction theory in general) want, but it is clear to me that the at-rest frame of reference (with what is measured) will always be the accurate, objective frame anywhere in the universe. If travelers through our solar system want to know the distances between objects at any given moment, they will need their Lorentz transformation equations to translate what they see, zipping by at near 'C' (maybe seeing 1/8th of our AU, for instance) into the actual, objective, intrinsic, as it is, independent of various observational differences... distances. (The latter are of course best known from the end points, at rest with the distances measured.) Anyway, all of the above must stand as my "theory of common sense." If you (generally speaking) have abandoned common sense, science is the poorer for it. Enough already.

We know that a lot of situations will slow down a clock. Among them are traveling at different velocities. This is not a mechanism, but it does require differences in acceleration... a force... to get them into different velocities. Putting them in different gravitational environments will change their rate of ticking too... Still not a "mechanism" but certainly a difference in force field. The ontological question this thread poses is, "What is time that 'it' slows down "dilates" in the above circumstances? Show how time is verified to be such an entity. I don't believe that it is... i.e., that there is no difference between "time dilation" (assuming that time is something) and clocks slowing down (observable/empirical.) I have no problem with the Lorentz transformations (LT) making sense of the differences between clocks as above so that we end up in the same moment in a plane heading toward a mountain and in a GPS telling the plane where it is in relation to the mountain. (In other words, please don't keep citing LT as a proof of time dilation.)

from my post 57: swansont, post 59: How did you answer what spacetime curvature adds to the mix? The spacetime- critical quotes in this thread do not attempt to debunk relativity in general, but rather question the nature of (ontology) and need for (Occam’s razor) spacetime to make those “successes” you listed work. You said in post 56: What part of spacetime curvature is required for the improved description of the above provided by GR. In other words, first (always), what IS spacetime, then how is spacetime curvature essential to GR? I know that all explanations of GR open with the assertion that mass curves “spacetime.” None, that I know of start with a consensus on what it IS. (The International Society for the Advanced Study of Spacetime has still not arrived at such a consensus after a decade of conferences and reams of papers on it.) The quoted critics in this thread (and many, many more, as above) ask, what is this stuff, spacetime supposed to be, that “it” is curved by mass. We know that gravity is some kind of pull between masses that makes, among other things, planets orbit the sun and light’s path get bent around masses, i.e., it acts as if it has mass. You said, “ “GR is a geometrical description.” No doubt... a system of coordinates for tracking and predicting the movements of particles/bodies through space over time. No problem. GR does it well. But what IS spacetime in all of that, that “it” is a malleable medium rather than just a system of coordinates? This is the topic of this thread. How about addressing it for a change? Ps; One, "for instance" among many: The "frame dragging" you mention as a curved spacetime confirmation can easily be explained by earth's topographical and crust density irregularities (not a smooth surface), which complicate the orbital positions of satellites... usually attributed to "frame dragging." (Spinning black hole "frame dragging" lacks enough evidence... re: the way stuff is sucked in... to be such a confirmation.)

TAR, You are off topic. Iggy, The clock in orbit, say on a GPS, ticks slower than one on the surface, because of its relatively higher velocity (they call it "time dilation")... and the gravitational difference (which requires adjustment), so relativity makes the corrections to give travelers (and their clocks) accurate positioning information. That is my point...clocks ticking slower with no need to claim that something called time slows down. The above does not concern itself with earth's velocity relative to our galactic center or our whole system relative to Andromeda. This is a red herring. Nobody cares, and it's off topic, how our clocks' velocities, on the surface or in orbit, compare to the velocity of clocks in to Andromeda Galaxy.

In a real conversation or debate, the argument that I am presenting logical fallacies would require some specifics about what makes my argument fallacious. You seem to like the cryptic answer without addressing the above at all. It's your choice but it is empty of substance. You clearly dislike ontological criticism of spacetime, and have totally dodged all arguments of that nature in this thread. If that is not bias, what else can it be called, and still be civil?

How about philosophical realism as an alternative... "objective reality?" So earth is either nearly spherical or almost squished flat, or various other shapes. How is that a false dichotomy? It can't be all of the above unless we discard realism (the possibility of an objective world) and just stick with, "It all depends on the way you look at it. Who knows?" And how is that not subjective, with frame of reference=subjective perspective? Here is where science could benefit from some serious philosophy... or not.

Cap ‘n R: The way I am using objective vs subjective in this thread is that objective refers to an object as it is, independent of observation, and subjective refers to how we see an object. So I have “amended” subjective idealism to apply to relativity with “frame of reference” substituted for “subjective.” Idealism still applies because the claim is that “how I see it is how it is,” or “how it looks to me from my perspective is how it actually is.” This is a form of idealism. It could be called relativity’s frame of reference idealism. Whatever we call it, it does not acknowledge an objective world (earth) or universe (realism) independent of perception or frames of observational reference. Cap ‘n R: I think it is reasonable and true that the earth’s shape has changed very little over the eons, as known through straightforward earth science physics. The spinning has caused the equator to bulge a bit, making that diameter longer than its polar diameter, but both are know to a very precise degree. Flying by at near ‘C’ and seeing earth as 1/8th of either diameter (depending on direction of flight) does not make it so. Idealism says, “What I see is what/how it actually is," but that is not what it objectively IS intrinsically, in and of itself (as per philosophical realism.) I think it would be an honest admission for relativity theory to acknowledge this difference between how we see it (from different frames of reference) and how it is objectively, and that the latter is more accurately known from at rest with with what is measured than from extreme velocity flying by, i.e., with probable visual image distortion. Going back to the meter rod again for the sake of simplicity... surely no one believes that with two identical rods, side by side, moving one away at near ‘C’ until it looks like 1/8th meter long actually means it IS 1/8th meter long for that period of observation... and then, when returned to rest frame, side by side with its “twin”, it becomes one meter long again. If you think the one gets shorter and then longer again (or earth morphs as above) just because it looks that way from the extreme frames, then I will no longer try to convince you otherwise, as I accept that length contraction is based on the above form of idealism. We can acknowledge relativity for what it does well without throwing common sense clear out the window. me: Cap ‘n: This sums it all up. It says that there is no objective world independent of reference frames... Clearly idealism as contrasted with realism as the basic philosophy of science behind the length contraction aspect of relativity.

Cap 'n R: Do you agree that the above means that there is no objective, as-it-is shape of earth? Every time you amend the description of earth to depend on frame of reference, as above, you subscribe to my amended version of subjective idealism which equates "subjective" with "frame of reference (FOR.)" The objective earth philosophy of science says it's shape is not dependent on who sees it from where and at what speed and vector. The FOR=subjective perception philosophy says that earth is (in fact) shaped in the various ways described above, depending on how it is seen from various angles and speeds. How is the above not an endorsement of the "FOR=subjective perception" philosophy as contrasted with the objective philosophy that the shape of earth does not depend on how it is seen. And, as I said before in reply to your earth-as-a-statue metaphore, the earth, unlike your statue, has been seen from all perspectives at rest with it, from surface measures to orbiting observation at all possible angles... So it still seems to me that your statue metaphor is totally irrelevant ("bogus" in the common vernacular.) If you flew by at near lightspeed, your statue would turn into a nearly two dimensional image, maybe 1/8the the thickness through the body of the actual stone from which it was carved. And I say "actual" as the close-up measurement I have been advocating as "more accurate" than thought experiments looking at it from "ridiculously high speeds."

Iggy, I mean that clocks in orbit are traveling at higher velocity relative to earth's center than clocks on the surface, and they slow down compared to the latter, (and the gravity factor is different.) Now, if you will re-read the "what slows down" point above again (clocks or "time") you will have the gist of my reply as per this thread's topic. I will not here repeat my take on Big Bang cosmology. I have covered that in detail in other threads. Leave it that cosmos is expanding outward at whatever velocity, and that its rate of expansion is accelerating. Point: There are many different scales considering what is traveling at what velocity relative to what.

So, according to what you just said, does the world-as-it-is (not changing) have an intrinsic, objective shape or does its shape depend on the frame of reference from which it is viewed?... which would make length contraction a form of 'frame of reference idealism.' Your above statement does not sort out and address the options in the quote: To include the spherical option, all four of the following statements can not be true. #1: Earth is nearly spherical. #2: Earth does not change shape. #3: Earth is flattened between the poles. #4: Earth is flattened through the equator. The 'all frames give equally valid descriptions' dictum clearly runs into a brick wall here. You really can't have all of the above be true. I get that no one sees earth morph as as you said. So (a little humor here) it must have changed (violating statement two above) when the ship was turning around (and the observers' backs were turned), because the first observation saw it as in #3 above, and second observation saw it as #4 above. And, of course, had they landed, as TAR suggested, they would have seen it as earth science sees it (from at rest frame), as #1 above. ????? An objective vs subjective ("subject"=frame of reference dependent) world is at stake here in terms of philosophy of science. Here is another way to address the contradiction, as I see it. You have said that earth does not change (in this context.) Then you said," The shape is only different between reference frames." It can not be different and yet not change. ????

Clocks on GPS satellites (I guess "satellites" is redundant here) are traveling at higher velocity around the center of earth than clocks on the surface. Of course earth is traveling at extremely high velocity around the center of the galaxy, and the latter at unknown but ultra-high velocity of expansion outward from the bang. But I don't think all of that is relevant to my point about clocks slowing down (observable) vs time slowing down (can't see "time".) The ongoing ontological question is, what slows here besides clocks?

This is a repeat of my challenge from post 78 (not addressed), directed to Cap 'n R, who introduced the thought experiment, later extended by TAR, bringing the contradiction into clear focus: This is a sincere challenge to the 'all frames of reference are equally valid' dictum of relativity (length contraction here specifically). I edited out the "Deal with it. (Please.)" For more civility and less confrontational attitude on my part. But avoidance of the question is not a mature scientific attitude.

swansont: No, I don't "want positive points." I wanted to (and did) criticize a "social network site" type popularity rating in a science site. How was my post bad, other than the obvious jugement from your bias, that you don't like ontological criticism of spacetime, even by well credentialed experts in the field?

A process question for admin: What is the point of the popularity rating function here by which I get another demerit for the above post quoting and commenting on ontological criticisms, the thread topic? The more I question mainstream time dilation, length contraction, and the nature of spacetime, the more demerits I get. What part of science is a popularity contest?

Swansont lists the most often quoted successes of relativity theory above without addressing exactly how "spacetime" is a necessary element. So, I hope to kick-start this thread again by repeating some quotes from the thread which were never addressed. me: (I've edited “space” to “spacetime” for more general application... my quote): From the Brown and Pooley paper:,"Minkowski’s spacetime: a glorious non-entity": (Abstract) me: Brown quoting Einstein: “It seems to me . . . that a physical theory can be satisfactory only when it builds up its structures from elementary foundations." (Ein- stein, 1993)12 “. . . when we say we have succeeded in understanding a group of natural processes, we invariably mean that a constructive theory has been found which covers the processes in question.” (Einstein, 1982, 228) me: Deeper into the text is the following Einsteinian perspective from Brown: me (again): “Ruts or grooves in what?”

TAR: I have agreed many times in many different ways that clocks slow down at high velocity and changes in gravity field. This is empirical science. We observe the above physical process in clocks. But the claim of time dilation is that "time itself slows down" under these conditions. The difference is of paramount importance to the ontology of time... "what is it?" We also observe that natural incoming muons have a longer than "expected" (from observing their lab cousins) "lifespan" during which they travel further than "expected." ("Time dilation" and "length contraction" are considered reciprocals in the above observations.) So the longer lifespan is called "time dilation" as if "time expanded" for these high speed particles, rather than simply seeing that they live longer. And the atmosphere through which they travel, well known to be around 200 miles, is "seen" as "contracting" to much less distance "for the muons." This is how time dilation and length contraction are examples of what I call "frame of reference idealism," negating an objective world independent of observation, and making all frames of reference ("for the muons" etc.) into equally accurate descriptions of the world. So, Earth IS various shapes, according to various frames of reference; Meter rods ARE way shorter as viewed from high speed frames... and "time expands" at high speed, etc. All of the above is ontology, about which most physicists don't give a hoot. Seems that the "objective nature of the world/cosmos" ( and philosophical realism) is not a relevant interest to many of them... and I though it (quoted) was the essence of science!

swansont: Cap 'n R originated the scenario above of high speed voyagers seeing earth as oblate (flattened) as per length contraction in the direction of their vector. He said that the shape of earth does not change but rather that it is flattened "for them." The flattened earth, he claimed, is just as accurate as the spherical earth, because 'there are no preferred frames of reference.' So, TAR's thought experiment, having them change vectors (frames of reference) seemed an excellent challenge to the assertion that, for them, earthis flattened in one direction... that it didn't become flattened but rather it always is flattened, from that FOR. So, the switch makes it obvious that the flattened shape first in one direction, then in the opposite is not "earth as it is" for one pass-by and then "earth as it is" for another pass at right angle to the first... unless, objectively, it's shape changed between passes. It can not be both ways: "Earth does not change shape...", and "Earth is flattened between the poles..." (for one FOR), *and* "Earth is flattened through its equatorial diameter" (for another FOR.) Deal with it. (Please.) I have never claimed that I am never wrong. Reference my "Another Far Out Cosmology" thread in Speculations. Here is a representative sample from the last page of that thread... to save you the trouble: Ps; You: Me: From #73: Seems that you agree with the above, saying that "Ideology does not drive reality," but that agreement must certainly be some kind of "distortion." Can you explain how length contraction is not "frame of reference idealism" (i.e., describes the real,objective world) considering the above "two passes" take on earth's two different shapes?

Just a quickie, the rest later. swansont: Seeing earth as flattened one way (say polar diameter 1/8 its earth- science- known length looking pole to pole) and then passing by again on a vector with its equatorial axis (nominal/theroretical) and seeing it flattened that way, say soon after the first pass... would give the theoretical, hypothetical, thought-experimental voyagers a very strong indication that the earth did not respond to their different vectors (frames of reference) by changing shape in response to their observational (FOR) shift. To be radically honest with your question, what puts me " in a position to say what science need or need not do?"... Maybe it has been my freedom from mainstream scientific indoctrination (as a lifelong amateur scientist) ... freedom from studying to get the answers "right" on all the physics tests and then getting the approval of the doctoral committee for a physics PHD, etc. My intense interest in things like, "What is time, space, and spacetime... the ontological part of philosophy of science keeps on investigating, and finding that there are many out there investigating the same ontological questions. And a physicist may not even care about the above if his/her focus is all on how the equations fit the theories, without a second thought to such obvious philosophical absurdities as an earth with no objective shape independent of various observational frames of reference. Finally, as to what "puts me in" such a position to criticize time dilation, length contraction and spacetime curvature (I will soon cite other spacetime critics, specifically if not banned first)... But you asked, so... one time only, because it draws extreme heat!... Heredity. Inherited genes. I am a free thinker with a measured IQ of 170 (SBIS); 178 (WAIS.) You can look up the "rarity of occurance" tables if you are interested, but statistically... ... never mind!

No. It was a comparison of the *principle* (the focus of this thread) that various perceptions do not create various corresponding objective properties of objects perceived. One must be a "frame of reference idealist", in this context, to believe the above, as I have argued. I thought that TAR gave an excellent example of Cap 'n R's spaceship voyagers perceiving earth as flattened in one direction in one pass, and then flattened in another direction in another pass, 90 degrees from the first. In that case, the change of reference frame and the corresponding change of perception of the "true shape of earth," (assuming it has an objective shape independent of perception) is even more obvious. I thought my analogy demonstrated the same principle without making sound wave compression into a "theory" asserting that the sound is a accurate indicator of engine rpm... like length contraction "theory" claims for earth's shape, even quite "distorted" from what earth science knows about its shape. To your last point, I do know that everything is in motion at all kinds of various velocities relative to everything else. But we can describe the relative velocities of bodies in our solar system (relative to each other)... and make very good and accurate sense of it all... without obsessing on all possible frames of reference, like: "relative to the center of our galaxy, earth is traveling at (whatever velocity)" added to its velocity in orbit around the sun, etc. We could even add estimated velocity of cosmic expansion and add that into a very complex "earth's actual velocity" scenario. But we can and do know its average velocity around the sun as a frame of reference without the larger scale frame. Likewise we know, "up close and personal", precisely the shape of earth from at rest frame without granting equal accuracy to a thought experimental perspective flying by at near light speed. We know, reasonably speaking from a-priori epistemology, that it isn't "actually, objectively" flattened out as seen above, but rather distorted by the extreme viewpoint from which it is so perceived. Science need not become a carnival of the absurd over the relativity dictum, "There are no preferred frames of reference." At rest with what is measured will always be the "preferred frame," according to the philosophy of realism here presented, not zipping by the measured object at near 'C.'

Well, TAR, I must say that it sounds like you didn't even read (or understand) my last post, beginning with the following: Of course it "takes time" for light/information to travel across any/all distance...signal delay. That does not create some medium, "time" through which light must travel or different "nows" at separated points/locations. But you seem to totally ignore the above, saying: The following statements are all true, according to presentism: Now, the present IS the present, not the past, not the future. The present is not a local phenomenon in each and every different "point/locus" in the universe. However, "it takes time" (event duration) for light and information to travel between loci. I gave the example that now is the same now (events happening in the ongoing present) here and on the sun, and that, of course what we now see on the sun happened over eight minutes ago. This all seems to me to belabor the obvious**, but the point relative to the thread subject is that neither time nor the omni-*present* now is a medium of any kind with malleable properties, for instance, in the case of "time" or local boundaries in the case of now, the present. ** I simply can not get your sense of meaning in: (My bold.)Must we re-define "is" to make sense of it? In what sense can either the past or the future be considered, "now, the present?" (The first is not still present; the second is not yet present!) Stuff happens. It "takes time." But events happening doesn't create something called time. I hope this clarifies presentism and time ontology, because I can think of no better/clearer way to present it.

How flawed? And how is a squished earth not an appearance error, given the precision of what earth science KNOWS, as above, about earth's shape, as a body, objectively speaking?

Could you give me an example of "how things behave" (say Mercury orbiting the sun... a classic relativity success story) with "spacetime" being curved in contrast to the mutual gravitation between the two bodies without the curved medium, spacetime? What does spacetime curvature add to gravity between them without it?

Bump.