owl Posted January 12, 2012 Author Posted January 12, 2012 Part of the title of Ross's paper doesn't make sense to me...what is the "Cosmology of Non-Euclidean Geometry"? It would make sense to me if it read; The Ontology of Non-Euclidean Geometry In Cosmology. Am I being thick here? The geometry is the conceptual aspect of locus points, lines, planes, and volume(s). The time factor is elapsed time for everything that moves... i.e., everything. So geometry is the mental map and cosmology is how that is projected into “the reality of the cosmos”... if that even matters for “modern mental models” of geometry. How it corresponds with the cosmos seems secondary to the magic of math and the internal integrity of the model... here in this forum, anyway. Good math that predicts events requires good understanding of the world that math attempts to describe. The latter is about meaning and relevance to "the real world"*... assuming, of course, that there is a real world. *But that is where philosophy of science comes in. If that is assumed to be a discredited field of study... as in this forum... object of ridicule and all, then there can be no serious discussion of 'what it is' and 'how it works' ... if idealism is the only prevailing 'ideology' here. The physicists here (the ruling body) are driven to dominate the philosophy forum. Too bad. I'm getting tired of it.
swansont Posted January 12, 2012 Posted January 12, 2012 Check the title of his paper against the title of this thread. You assume that all understanding of non-Euclidean geometry depends on being a mathematician. His paper is entitled: "The Ontology and Cosmology of Non-Euclidean Geometry." Ontology is the part of the philosophy of science which examines the meaning of the concepts (and existence of the entities) and assumptions which the math represents in symbols an formulae. Do the ontology of mathematics even make sense? I do not dispute that the latter was a reinvention of geometry, but I simply state that it was based on new *assumptions* dumping Euclid’s postulates. It also got rid of maybe the simplest principle in geometry, that the shortest distance between two points is a straight line. Swansont and I went a few rounds over this one. If you call the surface of a sphere a flat plane, then you can call lines drawn on it “straight lines,” but the shortest distance between two points on the surface of the sphere is still *straight through the sphere*, regardless of the intrinsic vs extrinsic curvature distinction made by non-Euclidean geometry, and covered in detail in Ross’ paper. Changing the conditions of an argument is an inherently dishonest tactic. A condition is that you stay on the surface. Ignoring that invalidates the response. Do you want to argue the semantics of “assumptions” or tell me where you think Ross was wrong, making his paper “crap?” While you are at it, how can parallel lines intersect and still be described as parallel? Simple. They fulfill the conditions described in Euclid's fifth postulate: they are both at right angles to a common line. On a flat surface they do not intersect. That fails on a curved surface. Again this is some semantics (a figurative description). Do you understand intrinsic vs extrinsic curvature? Do you deny that the shortest distance between two points is a straight line? Do you understand that a line in inherently two-dimensional, and leaving a surface violates the conditions of the math? You keep hammering on "lack of evidence" for the assertion that Earth is nearly spherical when in fact all known evidence verifies that, and there is no evidence to the contrary. It might appear very oblate from a high speed frame. The Cap 'n's last challenge to me in this context was to define "is." I contrasted "is" with "appears" and didn't hear from him again. Squeezed nuclei in an accelerator is not evidence that a squeezed Earth is equally valid. (Hundredth time or so on that point.) Squeezed nuclei is evidence for length contraction. I have agreed over and over that clocks slow down, etc., etc, but question the ontology of "time dilation" as a reification of time. To say that "time slows down" is quite different than to say that "clocks slow down." The difference is important. One implication is that, once time is reifiied, the "possibility" arises that we can "travel through it" to the past or future. You run and hide whenever I mention this. You don't exist in yesterday's future? What day is it in your world? Here it is again with the really beat to death example of Earth's diameter.** (Ref below) The diameter of Earth is a length, and Earth is not imaginary but a real body with an actual size and shape. You insist that "Length Is Not Invariant." The double negative means that length varies. So you insist that the diameter of Earth varies. That is the idealism of "no preferred frame of reference" in which the claim is that Earth IS how it is OBSERVED from different frames... therefore the shape of Earth varies with observation... which is false. Yes, the length varies. No the earth does not change shape, in any way that rigidity matters. What is length? What is it made of? OK. Again, I'm not an electrical engineer, and I will pick my brother's brain on it at first opportunity. This electrical nit picking was your derailment of my point, which still holds: that ammeters detect and measure the power of electric current in a wire or system... as a contrast with what clocks do (or not) with "time." Clocks tick. We can compare the conventional time units they tick off with other observed physical processes and then say that so much time elapsed. That is way different than the ammeter example. It's my example, with distractions removed. Don't change the subject. There is no explanation at all that I know of for "force across distance" in the examples I have used. That was my point. You and the other relativity advocates here are the ones saying that how it works doesn't matter as long as we can predict results. So it doesn't matter what 'spacetime' is or how mass curves it or how it guides objects into curved paths... as long as relativity is an improvement over Newtonian gravity theory... which it is. So, if Quantum theory of gravity with its "massless messenger particles", "gravitons" turns out to be another improvement, we can throw out GR's "spacetime." But we still will not know how mass attracts mass at a distance. I agree, we do not know, ultimately, how mass attracts other mass. Does that change the fact that it does? Instead of being paralyzed by the question we can't answer, I prefer to focus on the ones we can. But by all means, ponder away. Just don't tell me that gravity is a mystery. It may be a mystery to you, but you speak for nobody but yourself. You have in no way shown how (apparently) squeezed atomic nuclei in an accelerator transfers to an actually (not just apparently) "squeezed Earth." ... or how a massive rigid body like Earth could be so altered.... nor have you addressed the difference between "is very oblate" and "would appear very oblate", which is central to the difference between realism and the length contraction version of idealism which you promote. Again, length contraction is length contraction. ... more of the 'have you tested gravity in your living room' pseudo- argument. Yes. It is tested and verified with every step, as we all stick to what we are walking on. This is not an argument for flattened high speed nuclei applying to a flattened Earth, as seen from a high speed frame. This is going nowhere... still. I was referring to your insistence that length is a real thing, but that space is both empty and contains length. What is the density of length? What is it made of, this thing you call length? 1
owl Posted January 12, 2012 Author Posted January 12, 2012 Finally someone pointed this out. Anyone care to explain why the fact length can vary is worded as a double-negative? It's quite annoying and isn't the first time I've noticed such grammatical errors when reading scientific papers. An awful roundabout and clumsy way of saying that length can vary. [/Quote] Thanks for the supportive agreement... very rare here for me... boo hoo... nobody likes me... I'd like some clarification on this as well. In reading some of the responses in this thread it appears that they're saying the shape of the earth will depend on the frame of reference of the observer. Yes. It's basically belief that how we see it is how it is regardless of how extreme (velocity relative to what is observed, for instance) the frame of observation. Whether the object "changes shape" as in "length (of diameter) varies" or whether we just can not know an object's "true shape" (there is none in idealism)... has never been a clear consensus here among length contraction advocates. Now forgive me for being pedantic but seeing as we're the only sentient beings in the universe capable of observing anything, wouldn't that mean that there is only one relevant frame of reference. Where are these other frames of reference and who are these observers? The only ones asking about the shape of the planet are us humans and thus far, the correct answer remains "mostly spherical". Here is where we depart. How can you seriously assert that: "...we're the only sentient beings in the universe capable of observing anything, wouldn't that mean that there is only one relevant frame of reference." First there are very probably (statistically alone, even) uncountable systems in the universe capable of supporting not only sentient but intelligent life. Second: Frame of reference is an abstract perspective, not dependent on an intelligent observer. How it might look from various frames is the fallacy of appearance vs intrinsic properties, which I am debating with the length contraction advocates here. Somehow this discussion has devolved into a debate about the Theory of Relativity. So in that spirit, it should be noted that it is just a theory and that the recent findings at CERN are already casting shadows of doubt. Jus sayin' Please elaborate. This to the forum in general; a follow-up on TAR's sincere questioning of SR's invariability of the speed of light. Just to clarify: If length and time vary (length contraction and time dilation), how can we measure the speed of light in units of distance (length) and time (seconds) and call that velocity (miles per second, or whatever units) "constant?" Just askin'... along with TAR, who seems to have tired the usual run around with no answers, I presume.
tar Posted January 12, 2012 Posted January 12, 2012 Owl, Lurking about, with full intention of weaning myself off this forum, and getting back to my reading list, I see that my inability to make sense of Ross COULD be because he wasn't making any. And my inability to follow his reasoning was not because I couldn't think as deeply as he, but because he was looking at it wrong. In that light, I would like to add, as a (maybe) parting shot, a thought I had last night looking at the full moon on my drive home. I thought of you and your "real" sphere, and considered it odd that you would think such about the moon, being that it looked to me rather like a circle, with no third dimension at all. And being that the moon always has its same face to us, I was wondering why you would think it even had another side, much less a spherical shape. Where do you get such "ideas"? Maybe a cresent moon will remind me. But if light from the Sun reflects off the moon and gives the same pattern as light from a light bulb reflecting off a globe sitting on my sideboard, and I know the globe to be a sphere, I guess the moon might be as well. My thought is now, that if you are creating the idea of what shape a thing is, you have to model it, turn the model around in your hand or mind, and see if some similar characteristics and behaviors exist in the thing which is outside your reach, as those exhibited in the thing you have more information about. I don't think you can do this, but "over time". That is, put all the observations together, to get an idea of what the "thing" is, that you are describing or observing. In this "light", I would ask you to reconsider the "distance" between things, and consider the shadow of the Earth that the high speed traveler would pass through should she travel in such a way as the Earth would for a moment block the Sun. Is this shadow a "real" thing? What is its shape? Would she measure the shape of the Earth as a circle at any moment during its passage across the face of the Sun? I don't know the answer to this, but I think the question is useful, in considering the real "shape" of the Earth's shadow. I know there is an umbra and a penumbra because the Sun is not a point source, but if you were to project this shadow, in your "real" image of the solar system, would the shadow be straight or curved? You cannot exactly use experience of "straight" shadows you might note in a room. The solar system is quite huge and it takes light some time to cover the distance. And take the whole milky way. Which part of it is currently in the Earth's shadow? Tough to nail down in the "realist" camp. Don't you think? It would be sort of a spiral shape. Regards, TAR2
moth Posted January 12, 2012 Posted January 12, 2012 (edited) If length and time vary (length contraction and time dilation), how can we measure the speed of light in units of distance (length) and time (seconds) and call that velocity (miles per second, or whatever units) "constant?" Try a clock and a ruler. Then try comparing your result to another measurement made by somebody moving (say) away from you. You'll find both measurements agree on how much time elapsed while the light traversed how many rulers. Now explane how the same distance/time value is obtained in both measurements. Try contrasting these results with the results obtained with you standing on the side of the road and somebody (on a bike maybe)moving towards a car driving by on the road. Say the car is doing 100 m.p.h. the bike is doing 20 m.p.h and of course you're standing still. You measure the car going 100 the guy on the bike measures the car going 120. You've got to admit these situations are different or deny a constant speed of light. I looked at the paper you recommended. Maybe I should read it again though, because if anything the paper suggests to me: the fact we see 3-d geodesics as curves can only be because we are embedded in 4 dimensions. If we were only 3-d then 3-d geodesics should look straight. reason for edit: i've been in New Zealand for the last month. still kinda "fuzzy" Edited January 12, 2012 by moth
swansont Posted January 12, 2012 Posted January 12, 2012 This to the forum in general; a follow-up on TAR's sincere questioning of SR's invariability of the speed of light. Just to clarify: If length and time vary (length contraction and time dilation), how can we measure the speed of light in units of distance (length) and time (seconds) and call that velocity (miles per second, or whatever units) "constant?" Just askin'... along with TAR, who seems to have tired the usual run around with no answers, I presume. The changes are complementary, by the same factor. The observer in a moving frame (M) sees length contraction, while the stationary observer (S) see that M's clocks are running slow. The two changes cancel out, as they have to, to give c as a constant. (Of course, this was found the other way around — one starts with c being invariant and you derive these consequences, along with mass/energy equivalence.) I have agreed over and over that clocks slow down, etc., etc, but question the ontology of "time dilation" as a reification of time. To say that "time slows down" is quite different than to say that "clocks slow down." The difference is important. If time isn't real and as a result can't be measured, doesn't this affect more that relativity? Doesn't this throw all of physics that depends on time measurement onto the heap of "it's a mystery"?
owl Posted January 12, 2012 Author Posted January 12, 2012 (edited) The changes are complementary, by the same factor. The observer in a moving frame (M) sees length contraction, while the stationary observer (S) see that M's clocks are running slow. The two changes cancel out, as they have to, to give c as a constant. (Of course, this was found the other way around — one starts with c being invariant and you derive these consequences, along with mass/energy equivalence.) [/Quote] I'll let it go, since you already know my objections to "time dilation" and "length contraction." If distance traveled by light in a given elapsed time (say a year) varied as observed and clocked from different frames, then it would be meaningless to say that lightspeed is invariant. I understand the concept that your "time dilation" and "length contraction" are believed to be reciprocals of each other, i.e., complimentary. If time isn't real and as a result can't be measured, doesn't this affect more that relativity? Doesn't this throw all of physics that depends on time measurement onto the heap of "it's a mystery"? No. You continue to misrepresent my ontology of time. The concept of event duration of physical processes (my understanding of time) is a meaningful concept without the reification of insisting that time expands or dilates. Processes take more or less time in different situations. But I have repeated this ontology of time dozens of times and you still come back with, “If time isn’t real it can’t be measured." I’ve commented exhaustively on how we compare ticking clocks to observed natural events and say, in standardized units of time, that the event took so long. Yes, that is measurement without reifying time. swansont: I was referring to your insistence that length is a real thing, but that space is both empty and contains length. What is the density of length? What is it made of, this thing you call length? You belabor the obvious. We all know the answer to “How long is a meter stick?” (Duh.) “How long” is its length. A meter is a standardized unit of measure commensurate with the distance (another word for length) from equator to pole, i.e., one ten millionth of that distance or length on the curved quadrant of Earth. When you insist (over and over) that length is not invariant, it means that length varies, including Earth's diameter as an example of length. So you are insisting that the dimensions of objects change, i.e, Earth changes shape. Then you object to that statement. Owl, ... I thought of you and your "real" sphere, and considered it odd that you would think such about the moon, being that it looked to me rather like a circle, with no third dimension at all. And being that the moon always has its same face to us, I was wondering why you would think it even had another side, much less a spherical shape. Where do you get such "ideas"? Maybe a cresent moon will remind me. You can’t be serious! I get my ideas about the (nearly) spherical Earth, Moon, Sun, other planets, and other stars mostly from the well established science of astronomy. We have orbited the Moon quite a few times, and, sure enough, it is a ball of dirt and rock, not a flat circle/disk. We have directly seen all of the surface of the Moon and all of its features in great detail. If this is the level of your understanding and communication here in a science forum, it is just as well that you leave and study at least some basic Earth science and astronomy. My thought is now, that if you are creating the idea of what shape a thing is, you have to model it, turn the model around in your hand or mind,... Neither I nor science in general "create the idea of what shape a thing is" by mental modeling alone. We observe actual objects in the real world/cosmos, like in my example above. "...." ... and shadowy figures appear... so what is real? Enough already. What is the shape of Earth's shadow from various perspectives? Umm... that will depend on which perspective, for sure. swansont: Again, length contraction is length contraction. Aha! Now I get it! Why didn't you say so before? So when/if a meter rod appears to be only ten or fifteen cm long (its measured length from high speed frame) THAT is length contraction. Or like, similarly, the Sun appears to be only about a dozen or so million miles away... there it is again... length contraction. Thanks for clearing that up. swansont: I agree, we do not know, ultimately, how mass attracts other mass. Does that change the fact that it does? Instead of being paralyzed by the question we can't answer, I prefer to focus on the ones we can. But by all means, ponder away. Just don't tell me that gravity is a mystery. It may be a mystery to you, but you speak for nobody but yourself. You agree that we don't know how mass attracts mass, but I'm the only one who calls gravity a mystery? If it is not a mystery to you, then you are claiming to know how masses are mutually attracted! You contradict yourself. Ps: As per Brown and Pooley, they asked how "spacetime" functions... like what gets curved by mass and how does that 'whatever' guide objects in curved paths. If gravity is not a mystery to you, explain the above persistent ontological mystery of spacetime. (You've ducked this one many times before, though... so I expect that will continue.) Edited January 12, 2012 by owl
swansont Posted January 12, 2012 Posted January 12, 2012 I'll let it go, since you already know my objections to "time dilation" and "length contraction." If distance traveled by light in a given elapsed time (say a year) varied as observed and clocked from different frames, then it would be meaningless to say that lightspeed is invariant. I understand the concept that your "time dilation" and "length contraction" are believed to be reciprocals of each other, i.e., complimentary. You asked about the physics model, and that is the physics model. Why were you "just askin'" if you already knew the answer? No. You continue to misrepresent my ontology of time. I hope you will go back and notice those curly symbols at the end of the sentences in my post. We call those "question marks" and they indicate I was asking you to clarify, rather than making a statement. I submit that I cannot be misrepresenting your position while I am asking you to clarify it. The concept of event duration of physical processes (my understanding of time) is a meaningful concept without the reification of insisting that time expands or dilates. Processes take more or less time in different situations. But I have repeated this ontology of time dozens of times and you still come back with, “If time isn’t real it can’t be measured." I’ve commented exhaustively on how we compare ticking clocks to observed natural events and say, in standardized units of time, that the event took so long. Yes, that is measurement without reifying time. And here we see why I had to ask. because you have made it clear before that clocks don't measure time. Such as Clocks neither detect or measure anything. To claim that they do reifys time. When I asked you before about this, you didn't answer. I asked As for the other meters mentioned, the true ontological question is still a few layers deeper. But the topic of discussion here has been time and length, so the relevant comparison here is the meter stick. Doesn't a meter stick — a self-contained device — have a length, all by itself? So let's try this: clock are used for comparison. You compare the duration of an event to a clock. Is that a measurement? So I take it now that you can measure a duration, i.e. time. So if you have two identical events, and the duration of one event is smaller because it's in another frame of reference, what do we call this, without reifying anything? You belabor the obvious. We all know the answer to “How long is a meter stick?” (Duh.) “How long” is its length. A meter is a standardized unit of measure commensurate with the distance (another word for length) from equator to pole, i.e., one ten millionth of that distance or length on the curved quadrant of Earth. That's not what I asked. I asked what is length, not how long something is. i.e. I want the answer to the ontological question. I want to know how space can be empty and yet full of length, since you have said that length is a thing. I want the answer to the question I asked earlier, about whether a meter stick is simply an engineered device, since engineered devices don't measure anything (according to you). When you insist (over and over) that length is not invariant, it means that length varies, including Earth's diameter as an example of length. So you are insisting that the dimensions of objects change, i.e, Earth changes shape. Then you object to that statement. Yes, I object because you tied it into the rigidity of the earth, which has nothing to do with the subject. Relativity is not based on realism. Relativity is based on the postulates that the physics works the same in all frames and that c is the same in all frames, and this has a very sound foundation. I answer, based on realism, that the shape of Earth does not depend on how we look at it. The claim that it does is idealism, with "frame of reference" replacing "subject" (in subjective idealism), as the abstraction of 'frames' is understood. It behooves science to find the best way to look at it to determine its 'true shape.' That demands abandoning the dogma, "there is no preferred frame of reference", which length contraction advocates like you simply will not do. I implore you to look up the word dogma and learn the definition. If there were a preferred frame of reference, we could measure our speed with respect to it. This was debunked by the Michelson-Morley experiment, i.e. we have experimental confirmation of it, which means it cannot be dogma. Unlike philosophies that are not rigorously tested.
owl Posted January 12, 2012 Author Posted January 12, 2012 You asked about the physics model, and that is the physics model. Why were you "just askin'" if you already knew the answer?[/Quote] You know that I have always challenged time being something ('whatever') that dilates as contrasted with event duration in the natural world, which does not get longer or shorter just because the clocks "measuring it" go faster or slower. So we end up arguing about the meaning of the word "measure" and I contrast true meters with clocks... and off you go on another tangent about measurement. I also challenge the assertion that "real world lengths and distances" like between cosmic bodies or from one end of a meter stick to the other vary when observed from different frames of reference. You say frame of reference defines reality (idealsm) and I say reality is independent of frames of refererence from which it is observed. Therefore, Earth does not change shape (realism) just because you say "length is not invariant"* (a dogma of belief in denial of the reality of cosmos as it is... it all depends on observation... *meaning that length varies, meaning the diameter of Earth varies... (that means changes shape) with how you look at it. Do you believe that Earth changes shape with how you look at it or not? If not, do you believe that it is impossible to know its shape, because of the dogma that "there are no preferred frames of reference"... making all possible descriptions from different frames equal? If you will answer the above directly, we can proceed from there. Otherwise, I'll finish reply to your other points as "time" permits. Yes, it will take a few more minutes. I could "time" how long that takes, but you would take that wrong.
Cap'n Refsmmat Posted January 12, 2012 Posted January 12, 2012 Do you believe that Earth changes shape with how you look at it or not? If not, do you believe that it is impossible to know its shape, because of the dogma that "there are no preferred frames of reference"... making all possible descriptions from different frames equal? This rests upon the assumption that to "know" its shape means to have knowledge of the One True Shape. If one denies that there is a One True Shape, than this assumption is silly. I'd prefer to say I know the shape of the Earth, because I have made measurements and I can accurately predict what any observer will see when they look at the Earth. That is, functionally, it's silly to say I can't know its shape, because I can do everything you'd expect to be able to do if there were One True Shape: I can predict the results of experiments, make observations which accurately correspond to those of other observers, and so on.
owl Posted January 12, 2012 Author Posted January 12, 2012 (edited) swansont: I hope you will go back and notice those curly symbols at the end of the sentences in my post. We call those "question marks" and they indicate I was asking you to clarify, rather than making a statement. I submit that I cannot be misrepresenting your position while I am asking you to clarify it. I’ll be glad to clarify if you will be specific as to which of those little curly symbols you were referring. I have asked you so many questions that you have ignored, it’s hard to keep track... yet you expect answers. Be specific. And here we see why I had to ask. because you have made it clear before that clocks don't measure time. Such as View Postowl, on 4 January 2012 - 03:13 PM, said:Clocks neither detect or measure anything. To claim that they do reifys time. More bickering about the meaning of “measure.” See comparison of meters with clocks. s: When I asked you before about this, you didn't answer. I asked View Postswansont, on 6 January 2012 - 02:45 PM, said: As for the other meters mentioned, the true ontological question is still a few layers deeper. But the topic of discussion here has been time and length, so the relevant comparison here is the meter stick. Doesn't a meter stick — a self-contained device — have a length, all by itself? So let's try this: clock are used for comparison. You compare the duration of an event to a clock. Is that a measurement? You can call it that if you don’t meanwhile believe that clocks slowing down means that “time is dilating” as if you were "measuring" the rate at which "time" is slowing down. So I take it now that you can measure a duration, i.e. time. So if you have two identical events, and the duration of one event is smaller because it's in another frame of reference, what do we call this, without reifying anything? If you are comparing (clocking) natural events and comparing different clocks at different rates of oscillation (at different velocities, etc.), you can not say that one natural event was shorter in duration just because one clock slowed down while being compared to it (which you call “measuring.) View Postowl, on 12 January 2012 - 11:14 AM, said:You belabor the obvious. We all know the answer to “How long is a meter stick?” (Duh.) “How long” is its length. A meter is a standardized unit of measure commensurate with the distance (another word for length) from equator to pole, i.e., one ten millionth of that distance or length on the curved quadrant of Earth. s: That's not what I asked. I asked what is length, not how long something is. i.e. I want the answer to the ontological question. I want to know how space can be empty and yet full of length, since you have said that length is a thing. I want the answer to the question I asked earlier, about whether a meter stick is simply an engineered device, since engineered devices don't measure anything (according to you). Are you trying very hard to be difficult, or does it just come naturally?* Length is the concept of “from here to there” referring to objects in space or from one end of an object, say a stick, or from one side of Earth to the other. Not a difficult concept. Not a “thing” per se, but a concept describing real things and their dimensions or space between them, say in light years or meters or whatever. *“Full of length” just gave me a good chuckle. Thanks. View Postowl, on 12 January 2012 - 11:14 AM, said: When you insist (over and over) that length is not invariant, it means that length varies, including Earth's diameter as an example of length. So you are insisting that the dimensions of objects change, i.e, Earth changes shape. Then you object to that statement .s: Yes, I object because you tied it into the rigidity of the earth, which has nothing to do with the subject. Relativity is not based on realism. Relativity is based on the postulates that the physics works the same in all frames and that c is the same in all frames, and this has a very sound foundation. Whether Earth changes shape or not (not) has a lot to do with its rigidity. Does it or doesn’t it change shape? You say length varies. Its diameter is the distance (length) through it. Does it vary or not? View Postowl, on 7 January 2012 - 12:11 PM, said:I answer, based on realism, that the shape of Earth does not depend on how we look at it. The claim that it does is idealism, with "frame of reference" replacing "subject" (in subjective idealism), as the abstraction of 'frames' is understood. It behooves science to find the best way to look at it to determine its 'true shape.' That demands abandoning the dogma, "there is no preferred frame of reference", which length contraction advocates like you simply will not do. s: I implore you to look up the word dogma and learn the definition. If there were a preferred frame of reference, we could measure our speed with respect to it. This was debunked by the Michelson-Morley experiment, i.e. we have experimental confirmation of it, which means it cannot be dogma. Unlike philosophies that are not rigorously tested. Wiki on dogma: Dogma is the established belief or doctrine held by a religion, or a particular group or organization[1]. It is authoritative and not to be disputed, doubted, or diverged from, by the practitioners or believers. I’ll go with “particular group” above, that being length contraction/time dilation "believers." I have of course taken the license to liken your belief to religious dogma because you believe that how you look at things determines their reality, i.e., you don’t believe that Earth has a “true shape” of its own independent of that. I need not repeat what any scientist examining Earth would "prefer" as a frame from which to observe it and determine its true shape. To "examine" the effects of high speed travel past Earth as it might effect how it looks, of course your near 'c' fly by frame would be appropriate, if it ever becomes possible. This rests upon the assumption that to "know" its shape means to have knowledge of the One True Shape. If one denies that there is a One True Shape, than this assumption is silly. I'd prefer to say I know the shape of the Earth, because I have made measurements and I can accurately predict what any observer will see when they look at the Earth. No need to capitalize it and make it into a Diety or Platonic ideal. Yes, realism asserts that all cosmic objects have their own intrinsic shapes and properties, and they don't change with how we look at them. You length contractors believe otherwise. That is, functionally, it's silly to say I can't know its shape, because I can do everything you'd expect to be able to do if there were One True Shape: I can predict the results of experiments, make observations which accurately correspond to those of other observers, and so on. So did you get my distinction between "IS", as you challenged, and "APPEARS.?" If its shape doesn't depend on how it appears, it has intrinsic shape. (This is best known via close examination, as with all subject matter of science.) If it has no intrinsic shape... then it is as it appears... idealism. Edit; an afterthought on this swansont statement: "If there were a preferred frame of reference, we could measure our speed with respect to it." Neither the distance between nor the shape of objects in the cosmos depends on our frame of reference or our speed with respect to them. Measuring our speed (relative to whatever) changes nothing in the cosmos. "Relative to what?" does not describe the cosmos as it is... just how we see our little part of it. And our nice spherical (almost) planet will not change with how we look at it. Edited January 13, 2012 by owl
swansont Posted January 13, 2012 Posted January 13, 2012 You know that I have always challenged time being something ('whatever') that dilates as contrasted with event duration in the natural world, which does not get longer or shorter just because the clocks "measuring it" go faster or slower. So we end up arguing about the meaning of the word "measure" and I contrast true meters with clocks... and off you go on another tangent about measurement. Yes, it's abundantly clear that you have issues with physics. But you asked a question and I answered it, and I get static over having done that. I also challenge the assertion that "real world lengths and distances" like between cosmic bodies or from one end of a meter stick to the other vary when observed from different frames of reference. You say frame of reference defines reality (idealsm) and I say reality is independent of frames of refererence from which it is observed. Therefore, Earth does not change shape (realism) just because you say "length is not invariant"* (a dogma of belief in denial of the reality of cosmos as it is... it all depends on observation... *meaning that length varies, meaning the diameter of Earth varies... (that means changes shape) with how you look at it. And your assertion that realism is true is trivially falsified, but you change the subject whenever I introduce evidence that is more accessible. Instead, you insist on using a measurement that doesn't exist. It's reminiscent of Russell's teapot. If length varies, then any example is sufficient to show that length does not conform to realism. Do you believe that Earth changes shape with how you look at it or not? If not, do you believe that it is impossible to know its shape, because of the dogma that "there are no preferred frames of reference"... making all possible descriptions from different frames equal? dogma - a religious doctrine that is proclaimed as true without proof The existence of a preferred reference frame has been tested by attempting to measure our velocity with respect to it. We are not at rest with respect to it, but we are not moving with respect to it. Ergo, it is not proclaimed as true without proof. I’ll be glad to clarify if you will be specific as to which of those little curly symbols you were referring. I have asked you so many questions that you have ignored, it’s hard to keep track... yet you expect answers. Be specific. I asked If time isn't real and as a result can't be measured, doesn't this affect more that relativity? Doesn't this throw all of physics that depends on time measurement onto the heap of "it's a mystery"? And I asked because you said that clocks don't measure anything, and then said that they do. Then I find that you said that clocks do make measurements. So, which is it? More bickering about the meaning of “measure.” See comparison of meters with clocks. It's you bickering with yourself. If you are comparing (clocking) natural events and comparing different clocks at different rates of oscillation (at different velocities, etc.), you can not say that one natural event was shorter in duration just because one clock slowed down while being compared to it (which you call “measuring.) Ah, but that's not the scenario. I take two identical physical process, which have a duration, and measure them with the same clock. Or just compare them to each other. One of the physical processes takes place in a moving frame, so if the events started simultaneously, it will not end simultaneously. The durations are not the same. Are you trying very hard to be difficult, or does it just come naturally? My BS detector has been honed over the years. All I'm doing here is asking you to answer the same question that you ask of me (and others). Why is this a problem? * Length is the concept of “from here to there” referring to objects in space or from one end of an object, say a stick, or from one side of Earth to the other. Not a difficult concept. Not a “thing” per se, but a concept describing real things and their dimensions or space between them, say in light years or meters or whatever. So it's a concept now? OK. Now explain how a meter stick can measure length. A meter stick is simply an engineered device. According to your position, meter sticks detect/measure nothing. They are simply engineered to have a precise length … Do they create length and then measure it? (The italicized is from posts of yours with time-related words replaced with the appropriate length-related words) Whether Earth changes shape or not (not) has a lot to do with its rigidity. Does it or doesn’t it change shape? You say length varies. Its diameter is the distance (length) through it. Does it vary or not? It is different. Rigidity is not an issue — there is no force involved. It does not change in the way you are implying. It has a different value, because it does not have an inherent value. Wiki on dogma: I’ll go with “particular group” above, that being length contraction/time dilation "believers." I have of course taken the license to liken your belief to religious dogma because you believe that how you look at things determines their reality, i.e., you don’t believe that Earth has a “true shape” of its own independent of that. I have experimental evidence that supports my position. The notion is tested all the time, in fact, and it keeps passing the tests. You are free to dispute it by recreating the experiments that attempted to measure the preferred frame of the aether, or coming up with tests of your own. The way science disputes things is with scientific evidence. Anyone who taught about the scientific method should know this. I need not repeat what any scientist examining Earth would "prefer" as a frame from which to observe it and determine its true shape. Do we need to discuss what "preferred" means in this context? No need to capitalize it and make it into a Diety or Platonic ideal. Yes, realism asserts that all cosmic objects have their own intrinsic shapes and properties, and they don't change with how we look at them. You length contractors believe otherwise. Atoms and nuclei have intrinsic frequencies that they absorb and emit. But they change depending on the frame of reference one is in when observing them. And it doesn't matter if the source or detector is the one that is moving. How does that not falsify your assertion? And physics has lots of examples of properties that are not intrinsic. Kinetic energy is another obvious one. Edit; an afterthought on this swansont statement: "If there were a preferred frame of reference, we could measure our speed with respect to it." Neither the distance between nor the shape of objects in the cosmos depends on our frame of reference or our speed with respect to them. Measuring our speed (relative to whatever) changes nothing in the cosmos. "Relative to what?" does not describe the cosmos as it is... just how we see our little part of it. And our nice spherical (almost) planet will not change with how we look at it. That's what is meant by a preferred frame — where an object is absolutely at rest, and where the physics equations give the "true" answer that realism would seem to demand.
tar Posted January 13, 2012 Posted January 13, 2012 Owl, You know I know the shape of the moon. It is a different shape than it appears to be with the naked eye, from my car, when it is full. My point was that many measurements, at different times, taken from different perspectives, and from different sources are added up in my mind, and your mind, to determine what shape it always has. And from any one perspective, at any one time, it is still only a disc. You do not have any one "real" vantage point from which you can determine its sphereness. You have to hold an "ideal" that fulfills ALL the separate observations. You may think I am a dolt. But I am trying to point out to you, that you trust the measurements and observations of many, over spans of time, to fill out your understanding of the shape of the moon...then you stop trusting others, and figure you are holding the correct understanding and know the "real" shape of the moon...regardless of the continued observations, and idealizations that describe what that shape must be like. Yes it has a shape, regardless of who and when and from where it is observed. But your ideal of its real shape is your ideal, it is not the real shape. It is the understanding that you have of what its real shape must be, if all the information about it is added together. That is, from the best "god's eye" view you can manage. Together, people can manage a better "god's eye" view, than when acting alone. That is what science is about. Arriving at a better understanding of the shape of things. Don't know why you think that you can get there, without going along for the ride. And don't know why you think that scientists don't already know what they are looking at. Regards, TAR Underlying point being, that philosophy is relevant to science, but not "better than". You can form an ideal with philosophy. But it is not as good as testing it out, and seeing if it fits with reality. Like science does. 2
owl Posted January 13, 2012 Author Posted January 13, 2012 (edited) Swansont; I'll get back to point by point reply to your last post asap, but first some unfinished business. (from my notes... no time/ID stamp, sorry.) me: Do you believe that Earth changes shape with how you look at it or not? If not, do you believe that it is impossible to know its shape, because of the (edit: 'dictum') that "there are no preferred frames of reference"... making all possible descriptions from different frames equal? A direct answer for a change would be very much appreciated. You: dogma - a religious doctrine that is proclaimed as true without proof The existence of a preferred reference frame has been tested by attempting to measure our velocity with respect to it. We are not at rest with respect to it, but we are not moving with respect to it. Ergo, it is not proclaimed as true without proof. I explained the license I take in calling these phrases dogmas: A: “Length is not invariant,” i.e., it varies. B: “There are no preferred frames of reference.” “A” means that the shape of Earth varies (i.e., its diameter... a length.) “B” means that how we see it is how it is, from whatever frame, therefore we can not know its intrinsic, object shape, or if there is one. So, again, please answer my above questions. I edited out "dogma," replaced by “dictum”, a neutral word, so your answer need not endorse “A and B” as dogmas. Also,please explain your statement: “ We are not at rest with respect to it, but we are not moving with respect to it.” Seems one must be either moving or at rest with respect to any reference frame. Like in orbit around Earth is at rest with it, while flying by at near 'c' is obviously "moving with respect to it." Finally, I summarized realism yet again as follows: Neither the distance between nor the shape of objects in the cosmos depends on our frame of reference or our speed with respect to them. Measuring our speed (relative to whatever) changes nothing in the cosmos. Do you disagree? Do you think that “the world” and its properties and the distances between cosmic objects depend for their existence and properties, on frames of reference from which they are observed/measured or not? ydoaPs: A sphere is a two dimensional object-it has nothickness. I’m guessing you failed high school geometry. Summary review: A point is a locus with no “dimension.” A line is one dimensional. A plane is two dimensional. A volume ( all 3-D forms including a sphere) is three dimensional. ydoaPs: If we take a Euclidean space with a line on it and roll the space into a cylinder, the line is STILL straight. This is just you not understanding math. You don’t understand geometry, much less the transition from Euclidean to non-Euclidean. If you draw a line on a plane (lets not debate the ontology of “space” here now...) it is a straight line. If you roll the plane into a cylinder, the line becomes a circle, describing a “slice” of the cylinder, no longer a straight line. If you draw a line on the surface of a sphere, it is an arc, not a straight line. From the end points of that arc, a straight line is point to point through the sphere. I do not agree with non-Euclidean models of space nor the "rules" thereof, as swansont well knows from our debate over the above. This disagreement does not automatically make me (or other ontologists of geometry and cosmology) wrong, as you and swansont continue to assume... having no grasp of ontology* in the first place. *(Part of philosophy of science.) Edited January 13, 2012 by owl
moth Posted January 13, 2012 Posted January 13, 2012 If you draw a line on the surface of a sphere, it is an arc, not a straight line. From the end points of that arc, a straight line is point to point through the sphere. I do not agree with non-Euclidean models of space nor the "rules" thereof, as swansont well knows from our debate over the above. You see it this way because because you are looking at it from (at least) 3 dimensions, not the 2 dimensions of the surface. We have to be 3-d to see the arc in the 2-d surface, do you deny that we must be 4-d to see 3-d geodesics as curved?
owl Posted January 13, 2012 Author Posted January 13, 2012 (edited) You see it this way because because you are looking at it from (at least) 3 dimensions, not the 2 dimensions of the surface. We have to be 3-d to see the arc in the 2-d surface, do you deny that we must be 4-d to see 3-d geodesics as curved? There are only three dimensions of space. The rest are “theoretical/imaginary” models in theorists’ minds. (Time is about movement through/in space.) I am looking at the sphere I spoke of from the space beyond the sphere. This is still in 3-D space beyond the surface of the sphere. The surface of the sphere is curved. Obviously. Draw what you like on it, conceptually. The cosmos stays the same. All three spatial dimensions plus the time factor... moving between here and there. Gotta go again. Didn’t get to my point by point argument with swansont yet. Maybe later. One more piece before I go. You asked: "We have to be 3-d to see the arc in the 2-d surface, do you deny that we must be 4-d to see 3-d geodesics as curved?" Yes. There is no "4-d" space but in mental models. "Time" is a factor (movement) but not a dimension. Btw: Regarding your, "We have to be 3-d to see the arc in the 2-d surface,..." (Edit... details..): The arc was on the surface of the sphere, which is a 3-d object with a 3-d survace... not a flat 2-d plane. Science as it relates to the real cosmos is not about conceptual dimension shifting. It is not about the observer, "we." It is an objective focus in science at its best. How many dimensions do you think there are? Please describe them as best you can. Edited January 13, 2012 by owl
moth Posted January 14, 2012 Posted January 14, 2012 I am looking at the sphere I spoke of from the space beyond the sphere. This is still in 3-D space beyond the surface of the sphere. The surface of the sphere is curved. Obviously. Draw what you like on it, conceptually. The cosmos stays the same. All three spatial dimensions plus the time factor... moving between here and there. ... There is no "4-d" space but in mental models. "Time" is a factor (movement) but not a dimension. How do we see 3-d geodesics as curves if we are not also looking at volume from a hypervolume? How many dimensions do you think there are? Please describe them as best you can. At least 4: height, width, depth, and duration.
swansont Posted January 14, 2012 Posted January 14, 2012 A direct answer for a change would be very much appreciated. I'm sure you are familiar with the concept of equivocation. You are using change is a different way than I would use change, which you have made clear by introducing the concept of rigidity. As such, I can't answer the question the way you've worded it. The shape of the earth, indeed any length along the direction of travel, depends on your frame of reference. An observer on the earth will notice no difference — no change, as indeed he can't, due to the motion another observer. A "change" in the shape implies that there is an inherent shape to change, and you have demonstrated that you understand that this is not the position of physics. Physics is not based on and rejects realism. Physics/science is based on (among other things) the concept that measurement is reality, because that is our only source of information. You taught this, didn't you, as part of your course? To disprove a theory, one cannot rely on a thought experiment or assertion. (Something else you should have taught). To show length contraction wrong, you need to have an experiment where physics says it should be true and fails to hold. Similarly, all I need is an experiment that shows that properties are different if in a different frame. You've actually provided this — you agree that moving clocks slow down. Yet they are engineered to tick at a certain rate, and that changes. Doesn't realism say that this shouldn't happen? And there are all the other examples you keep ignoring. I explained the license I take in calling these phrases dogmas: A: “Length is not invariant,” i.e., it varies. B: “There are no preferred frames of reference.” “A” means that the shape of Earth varies (i.e., its diameter... a length.) “B” means that how we see it is how it is, from whatever frame, therefore we can not know its intrinsic, object shape, or if there is one. So, again, please answer my above questions. I edited out "dogma," replaced by “dictum”, a neutral word, so your answer need not endorse “A and B” as dogmas. These are conclusions from numerous experiments. You are free to challenge them, as indeed many people have done, by running an experiment. Funny thing is, all of the tests confirm relativity. Also,please explain your statement: “ We are not at rest with respect to it, but we are not moving with respect to it.” Proof by contradiction. It must be true that we are either moving or at rest with respect to a preferred frame. Since the answer is that neither is true, the logical conclusion is that there is no preferred frame. And there are literally millions of confirmations of this — physicists choose a calculationally convenient frame of reference all the time — they are not forced to do the calculation in one particular frame. And the physics works. Seems one must be either moving or at rest with respect to any reference frame. Like in orbit around Earth is at rest with it, while flying by at near 'c' is obviously "moving with respect to it." True. But neither one gets to say "my frame is right and yours is wrong" (if the frames are inertial). The physics works out either way. Finally, I summarized realism yet again as follows: Do you disagree? Do you think that “the world” and its properties and the distances between cosmic objects depend for their existence and properties, on frames of reference from which they are observed/measured or not? No, I do not. I can do numerous measurements that depend on the frame of reference, ones that are much more convenient to check. But these debunk realism, and there never seems to be any followup to them. The frequency of light depends on your frame of reference. The kinetic energy of a body depends on your frame of reference. I thought realism said that properties are inherent and not relative. I’m guessing you failed high school geometry. Survey says: owl failed geometry http://en.wikipedia.org/wiki/Sphere A sphere (from Greek σφαῖρα — sphaira, "globe, ball"[1]) is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point.… In mathematics, a careful distinction is made between the sphere (a two-dimensional spherical surface embedded in three-dimensional Euclidean space) and the ball (the three-dimensional shape consisting of a sphere and its interior). IOW, a sphere is a surface. This disagreement does not automatically make me (or other ontologists of geometry and cosmology) wrong, as you and swansont continue to assume... having no grasp of ontology* in the first place. *(Part of philosophy of science.) No, it's your flawed arguments that make you wrong. It's also kind of ironic that someone who admittedly "doesn't speak math" can pontificate about how others don't understand math.
DrRocket Posted January 14, 2012 Posted January 14, 2012 Finally someone pointed this out. Anyone care to explain why the fact length can vary is worded as a double-negative? It's quite annoying and isn't the first time I've noticed such grammatical errors when reading scientific papers. An awful roundabout and clumsy way of saying that length can vary. "Invariant" is a precise technical term which means that a quantity takes on the same value in all reference frames. Thus the spacetime interval is an invariant quantity. There is no double-negative involved, if one understands the language. To say that a quantity is "not invariant" has a precise meaning. To say that a quantity is "variant" is meaningless gibberish in the context of relativity. Like ow,l you seem to think that you can critique a scientific theory without first understanding what it says and the language, mathematics, in which it is formulated. That is ridiculous.
md65536 Posted January 14, 2012 Posted January 14, 2012 Survey says: owl failed geometry http://en.wikipedia.org/wiki/Sphere Perhaps you should brush up on how owl defines "sphere". Personally, I define sphere as "a perfectly round three dimensional thingy including the middle part". You'll notice that in your link, it says that "In mathematics, a careful distinction is made between the sphere [...] and the ball". We were talking about geometry here, not mathematics. It's common sense that a sphere has to have a middle part. You seem to be forgetting that we're in the philosophy forum. We're not "in" mathematics. owl was clearly talking about the Philosophy of Geometry. While you were busy failing Philosophy of Geometry, owl was probably teaching it. -2
swansont Posted January 14, 2012 Posted January 14, 2012 Perhaps you should brush up on how owl defines "sphere". Personally, I define sphere as "a perfectly round three dimensional thingy including the middle part". You'll notice that in your link, it says that "In mathematics, a careful distinction is made between the sphere [...] and the ball". We were talking about geometry here, not mathematics. It's common sense that a sphere has to have a middle part. You seem to be forgetting that we're in the philosophy forum. We're not "in" mathematics. owl was clearly talking about the Philosophy of Geometry. While you were busy failing Philosophy of Geometry, owl was probably teaching it. Last time I checked, geometry was part of mathematics. 1
owl Posted January 14, 2012 Author Posted January 14, 2012 How do we see 3-d geodesics as curves if we are not also looking at volume from a hypervolume?[/Quote] Take a basketball... a spherical shape with a curved surface. It is a 3-d object with 3-d space both inside and beyond it. An observer looks at the ball from the 3-d space beyond it, the room or a wide open space without walls. No "hypervolume" (whatever that is supposed to be) required. At least 4: height, width, depth, and duration. Me too, though I would rather not call elapsed time for movement (duration) another dimension. But that is common and I can get over it. But you say, "at least." Don't three spatial dimensions exhaustively describe space/volume? After front-back; left-right; and up-down, what other axis/dimension applies... what additional direction would a 4th spatial dimension describe? Some catch-up and follow-up before I take off for the weekend (Again from notes without time/ID stamps... just not convenient for me for review.): swansont: “Doesn't a meter stick — a self-contained device — have a length, all by itself?” Yes, it does. You are the one claiming that it's length varies with frame of reference. “All by itself” is a realist phrase... that it is intrinsic to the stick, not variable with how it is observed. me: “When you insist (over and over) that length is not invariant, it means that length varies, including Earth's diameter as an example of length. So you are insisting that the dimensions of objects change, i.e, Earth changes shape. Then you object to that statement.” you: Yes, I object because you tied it into the rigidity of the earth, which has nothing to do with the subject. Relativity is not based on realism. This is tedius. Given that the length of Earth’s diameter (which determines its shape) doesn’t change, you are wrong to insist that length is not invariant, i.e., that it varies. I have asked very directly many times, most recently, “Do you believe that Earth changes shape with how you look at it or not? If not, do you believe that it is impossible to know its shape, because of the (edit: dictum, not dogma) that "there are no preferred frames of reference"... making all possible descriptions from different frames equal?” Or again: “Whether Earth changes shape or not (not) has a lot to do with its rigidity. Does it or doesn’t it change shape? You say length varies. Its diameter is the distance (length) through it. Does it vary or not? You “answered”: It is different. Rigidity is not an issue — there is no force involved. It does not change in the way you are implying. It has a different value, because it does not have an inherent value.” Do you really call that an answer to “Does Earth’s shape vary or not?” No one is claiming that a squishing force is involved. You claim that the length of its diameter (shape) varies, i.e., “is not invariant.” I have a very good built in bs detector too, and this is a pile of it. Here it is again: me: you believe that how you look at things determines their reality, i.e., you don’t believe that Earth has a “true shape” of its own independent of that. You: “I have experimental evidence that supports my position.” Do you mean your position that Earth has no true shape ‘all by itself’ or that it changes shape or that we can not know its shape... all frames being equal and all? And again, me: I need not repeat what any scientist examining Earth would "prefer" as a frame from which to observe it and determine its true shape. You: Do we need to discuss what "preferred" means in this context? Yes. If relativity insists on the “no preferred frame” dictum, and we want to get the best possible info on Earth, it will not be by flying by it at very high speed. S: “We are not at rest with respect to it, but we are not moving with respect to it.” Review my challenge to the above. Are you sticking with this obvious contradiction or not?” Now back to time reification: S: Ah, but that's not the scenario. I take two identical physical process, which have a duration, and measure them with the same clock. Or just compare them to each other. One of the physical processes takes place in a moving frame, so if the events started simultaneously, it will not end simultaneously. The durations are not the same. We agree that physical processes like clock oscillations slow down when accelerated to different velocities. But if you are timing/clocking an event like say how long it takes a ball to drop 1000 feet, with different clock readings from clocks going different velocities... with “seconds” timing the drop differently, does not mean that elapse time for the ball dropping varied with the different “measurements” ... number of ‘ticks” simultaneous with the drop. Clocking an event differently as above does not mean that the event duration itself varied. If "time is that which clocks measure"* and they "measure" the same event differently, the fallacy of the tautology* becomes obvious. S: Now explain how a meter stick can measure length. A meter stick is simply an engineered device. According to your position, meter sticks detect/measure nothing. They are simply engineered to have a precise length … Do they create length and then measure it? (The italicized is from posts of yours with time-related words replaced with the appropriate length-related words) One more time... Yes, I can measure the length of a board with a tape “measure.” I can “measure” the duration of a race with a stopwatch. The length of the board will not vary under extreme observation yielding a very much shorter “length.” The elapsed time for the race will not vary with which of a variety of clocks in different frames “measure” it. The difference between “time dilates” and “clocks tick at different rates” is an important ontological distinction... which is lost on you. Ps; swansont: you agree that moving clocks slow down. Yet they are engineered to tick at a certain rate, and that changes. Doesn't realism say that this shouldn't happen? And there are all the other examples you keep ignoring. No, realism doesn't say that. Realism recognizes that various physical processes slow down for many reasons. I said that none of us knows what it is about different velocities* or different gravity fields that makes clocks slow down. I said that "relativity" is not such an explanation. It remains a mystery, like gravity... which, btw you claimed is not a mystery to you, but just to me... though you 'run and hid' every time I ask "what does mass curve and how does that 'whatever' guide objects in curved paths?" *Surely the acceleration required to move clocks into different velocities is a possible contender for what "force" might be involved, as is the force of gravity as another variable.
moth Posted January 14, 2012 Posted January 14, 2012 Take a basketball... a spherical shape with a curved surface. It is a 3-d object with 3-d space both inside and beyond it. An observer looks at the ball from the 3-d space beyond it, the room or a wide open space without walls. No "hypervolume" (whatever that is supposed to be) required. That is how we see 2-d geodesics as curves, by looking at them from a 3-d perspective. If you ignore the third dimension and stick with the 2 dimensions of the surface then the great circles in the surface of the basketball are not 2-d curves they are 2-d geodesics. If we see 3-d geodesics as curves, we must be looking from 4-d hypervolume. Don't three spatial dimensions exhaustively describe space/volume? After front-back; left-right; and up-down, what other axis/dimension applies... what additional direction would a 4th spatial dimension describe? This is basically the definition of 3-d volume, three axis' are all you need to fully describe a 3-d volume. Two axis' are all you need to describe 2-d area, there is no (meaningful) way to insert another axis in a 2-d surface, but that doesn't make 3-d volumes impossible. The fact that there's no "room" for a forth axis in a volume says nothing about a forth axis in a hypervolume.
swansont Posted January 15, 2012 Posted January 15, 2012 Yes, it does. You are the one claiming that it's length varies with frame of reference. “All by itself” is a realist phrase... that it is intrinsic to the stick, not variable with how it is observed. And I have evidence that it does, all consistent with relativity. But your objection to clocks measuring time is that clocks are simply "engineered devices". So, given that both are concepts, how is it that a meter stick can measure length, while a clock does not measure time? Do you really call that an answer to “Does Earth’s shape vary or not?” No one is claiming that a squishing force is involved. If you acknowledge that there is no force involved, why did you bring rigidity into the discussion? Do you mean your position that Earth has no true shape ‘all by itself’ or that it changes shape or that we can not know its shape... all frames being equal and all? The shape you measure depends on the frame of reference you are in. Yes. If relativity insists on the “no preferred frame” dictum, and we want to get the best possible info on Earth, it will not be by flying by it at very high speed. This is not about measurement error, a surprising mistake for someone who has taught these concepts — an expert — to make. Review my challenge to the above. Are you sticking with this obvious contradiction or not?” As I stated, the contradiction logically proves that there cannot be a preferred frame of reference. We agree that physical processes like clock oscillations slow down when accelerated to different velocities. But if you are timing/clocking an event like say how long it takes a ball to drop 1000 feet, with different clock readings from clocks going different velocities... with “seconds” timing the drop differently, does not mean that elapse time for the ball dropping varied with the different “measurements” ... number of ‘ticks” simultaneous with the drop. Why are you changing the conditions of the example (again)? I stated that the clock is at rest, and the identical physical processes take place in different frames. And yet the do not begin and end simultaneously. How does realism explain this — isn't event duration an intrinsic property of a physical process? I can measure the length of a board with a tape “measure.” I can “measure” the duration of a race with a stopwatch. The length of the board will not vary under extreme observation yielding a very much shorter “length.” The elapsed time for the race will not vary with which of a variety of clocks in different frames “measure” it. The difference between “time dilates” and “clocks tick at different rates” is an important ontological distinction... which is lost on you. "time dilates" is a figurative expression that apparently is lost on you. In physics, time is a legitimate variable. It, like length, is not invariant. But neither is a real, physical thing. The so-called reification happens when one takes literally that which is meant figuratively. I've given you the equation before, but you turned your nose up at it and never explained how it reified time. [math]\Delta{t'} = \frac{\Delta{t}}{\sqrt{1-\frac{v^2}{c^2}}}[/math] How does this reify time? This is the actual physics. Not the words. No, realism doesn't say that. Realism recognizes that various physical processes slow down for many reasons. I said that none of us knows what it is about different velocities* or different gravity fields that makes clocks slow down. I said that "relativity" is not such an explanation. It remains a mystery, like gravity... which, btw you claimed is not a mystery to you, but just to me... though you 'run and hid' every time I ask "what does mass curve and how does that 'whatever' guide objects in curved paths?" Answering a question, albeit not in a way that agrees with your philosophy, is not running and hiding. But since you seem to have missed it, the curvature is in the geometry we use to describe the 4D space. Why does realism not insist on physical processes staying the same when observed from a different frame of reference? i.e. we aren't discussing environmental effects here — only the observer's frame. Isn't that the essence of realism? If that property isn't the same in all frames then realism isn't an absolute, now is it? How can you insist on any other property being the same in all frames? And what about the other properties that you keep ignoring when I bring them up? Why don;t the stay the same in other frames of reference? Does realism only apply to length? *Surely the acceleration required to move clocks into different velocities is a possible contender for what "force" might be involved, as is the force of gravity as another variable. Yes, scientists are complete morons and never thought of this. Never tested it many, many times to see if there was a force that was the culprit.
owl Posted January 15, 2012 Author Posted January 15, 2012 That is how we see 2-d geodesics as curves, by looking at them from a 3-d perspective. If you ignore the third dimension and stick with the 2 dimensions of the surface then the great circles in the surface of the basketball are not 2-d curves they are 2-d geodesics. If we see 3-d geodesics as curves, we must be looking from 4-d hypervolume. [/Quote] You speak of "hypervolume" as if you have a clue what it means. To what dimension does it refer beyond 3-d space/volume? A curved line on a basketball surface (3-d, not a flat plane) is a 3-d curved line. If you ignore the third dimension, you are confined to a 2-d surface, a flat plane... but why ignore the fact that the ball/sphere is a 3-d object? This is basically the definition of 3-d volume, three axis' are all you need to fully describe a 3-d volume. Two axis' are all you need to describe 2-d area, there is no (meaningful) way to insert another axis in a 2-d surface, but that doesn't make 3-d volumes impossible. The fact that there's no "room" for a forth axis in a volume says nothing about a forth axis in a hypervolume. I agree. Once we define our geometry... line, plane, volume... of one, two and three dimensions, respectively, all confusion is clarified. You can stick to a 2-d plane and ignore the third dimension (volume), but that doesn't make it go away. And saying the word "hypervolume" does not describe another dimension. Theorizing seven more dimensions beyond 3-d space and time doesn't make them 'real' descriptions of 'more dimensions either'... as M-theory presents... pure metaphysics using esoteric math symbols and invented dimensions... as if it were real science.
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