A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Peter Webb on 16 Feb 2010 23:55 "mpc755" <mpc755(a)gmail.com> wrote in message news:3c8112b0-e86e-4fdb-a9f6-6c390200aa01(a)b2g2000yqi.googlegroups.com... On Feb 16, 9:26 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > > __________________________________ > > > My tabletop is not in a spaceship, and there is no train on the > > > spaceship. > > > > Here is my question. Lets just take the first half this time: > > > > 1. We place two atomic clocks on a tabletop at the centre of a 1 metre > > > ruler. We separate them very slowly so they are at either end of the > > > one > > > metre ruler. We record the time taken (according to the clocks) for > > > light > > > to > > > travel 1 metre in a vacuum. Will the speed of light measured in this > > > manner > > > be c or some other value? > > > Is the aether at rest with respect to the table top? > > > _________________________________ > > No. The tabletop is moving at speed of v relative to the ether. > > The the tabletop is the train. > > __________________________________ > No, a tabletop is a tabletop. Its not a train. And you haven't answered my > question. Will the speed of light measured in this manner be c or some > other > value? It is a pretty simple question. Why won't you answer it? I have answered it several times. If you want to understand how the clocks on the tabletop behave read my posts and replaced 'train' with 'tabletop'. _______________________________________ Or, you could simply answer my question. Its pretty simple. Will the speed be measured as c, or some different value. I will make it easy for you: If the earth is moving at velocity v with respect to the ether, and we perform the very simple experiment above, then will the measured speed of light in a vacuum be measured as c in a laboratory on earth? Well?
From: Peter Webb on 16 Feb 2010 23:58 "mpc755" <mpc755(a)gmail.com> wrote in message news:f6d7f0a4-a27c-476d-8098-8b877d62a849(a)b18g2000vba.googlegroups.com... On Feb 16, 9:26 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > > __________________________________ > > > My tabletop is not in a spaceship, and there is no train on the > > > spaceship. > > > > Here is my question. Lets just take the first half this time: > > > > 1. We place two atomic clocks on a tabletop at the centre of a 1 metre > > > ruler. We separate them very slowly so they are at either end of the > > > one > > > metre ruler. We record the time taken (according to the clocks) for > > > light > > > to > > > travel 1 metre in a vacuum. Will the speed of light measured in this > > > manner > > > be c or some other value? > > > Is the aether at rest with respect to the table top? > > > _________________________________ > > No. The tabletop is moving at speed of v relative to the ether. > > The the tabletop is the train. > > __________________________________ > No, a tabletop is a tabletop. Its not a train. And you haven't answered my > question. Will the speed of light measured in this manner be c or some > other > value? It is a pretty simple question. Why won't you answer it? How is the tabletop able to move at 'v' with respect to the aether? It's on a train. ________________________________ It is not on a train. It is on a tabletop. And it moves relative to the ether because I have already stated that it is moving at velocity v with respect to the ether. So, is the speed on earth measured at c or some other value?
From: Ste on 17 Feb 2010 08:14 On 16 Feb, 13:53, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > I never said it didn't *represent* physical reality, at least in some > way. But my ability to understand requires me to translate that > representation into something physical and concrete. > ___________________________ > A lot of people have trouble understanding abstract concepts. You shouldn't > feel shy about this, but you may take it as a sign that possibly physics is > not for you. I don't have too much trouble understanding abstract concepts within their own terms, if I'm inclined to familiarise myself with them. But if the abstract concept is supposed to describe something physical, then I wouldn't claim to "understand" unless I could indeed translate it into something concrete. Indeed when I say "I don't understand", I may sometimes be using it as a polite synonym for having actually made a judgment that "this theory is obviously ludicrous and unworkable as an explanation for the phenomenon that was to be explained".
From: Peter Webb on 17 Feb 2010 08:25 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:9b31d2c9-e699-41a8-a366-bc2f407ad017(a)o30g2000yqb.googlegroups.com... > On 16 Feb, 13:53, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: >> I never said it didn't *represent* physical reality, at least in some >> way. But my ability to understand requires me to translate that >> representation into something physical and concrete. >> ___________________________ >> A lot of people have trouble understanding abstract concepts. You >> shouldn't >> feel shy about this, but you may take it as a sign that possibly physics >> is >> not for you. > > I don't have too much trouble understanding abstract concepts within > their own terms, if I'm inclined to familiarise myself with them. But > if the abstract concept is supposed to describe something physical, > then I wouldn't claim to "understand" unless I could indeed translate > it into something concrete. > > Indeed when I say "I don't understand", I may sometimes be using it as > a polite synonym for having actually made a judgment that "this theory > is obviously ludicrous and unworkable as an explanation for the > phenomenon that was to be explained". Well, its obviously not ludicrous, because it works. The experimental evidence is overwhelming. That is seems ludicrous to you is because you don't understand some key concepts; one is the mathematics, and the other relates to the philosophy of science. I might add that I have never heard of anybody who understood the mathematics but thought SR (or GR for that matter) as being "ludicrous"; if you were somewhat less lazy or considerably brighter (or perhaps both) you could learn the maths as well and by the time you have learned Maxwell and Minkowski you won't think its ludicrous, you will think SR (at least) is obvious. But alas, lazy and stupid, that is a recipe for being a crank, not understanding science.
From: Ste on 17 Feb 2010 09:19
On 16 Feb, 13:54, mpalenik <markpale...(a)gmail.com> wrote: > On Feb 16, 7:59 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > You seem to insist that 4 dimensional spacetime is some abstract > > > philosophical thing when really, it's nothing of the sort. The real > > > world exists as a 4 dimensional manifold. That's not dependent on > > > mathematical tricks. You have a four dimensional space. We call one > > > of those dimensions time. > > > > You percieve a 3 dimensional world. But you have to realize that's > > > only your perception and that the universe exists outside of your > > > perception. > > > No we don't perceive a 3D world. We perceive a 4D world, and have done > > since the beginning of time (as it were). > > Which also exists independently of our perceptions. Yes I certainly agree that the world exists independently of our consciousness or our interpretation of it. > >That's what I'm saying to > > you: the real world existed long before geometry. And geometry is just > > a mathematical formalisation of basic concepts that were already > > physically obvious to anyone who ever considered the issue. > > This has nothing to do with rotation, which also exists independent of > human mathematics. Rotation and orientation are physical things with > physical consequences. > > I also think you might be confusing geometry with coordinate dependent > descriptions of geometry. For example, length is a geometric > property, which is independent of coordinate descriptions. Length is > a property that an object has--i.e. the rod is longer than this other > rod. It's not an algebraic or coordinate dependent property. Perhaps. I don't really understand the distinction that you're describing. > > > I understand relativity in the actual terms of the way the universe > > > really works. You're looking for something that conforms to your > > > specific desires, which relativity does not. > > > > Let's try it this way: what about the picture I drew for you do you > > > not think could represent physical reality? > > > I never said it didn't *represent* physical reality, at least in some > > way. But my ability to understand requires me to translate that > > representation into something physical and concrete. The idea that the > > representation means anything in itself is just absurd to me. > > So, the problem is actually that you find what the picture describes > absurd so you reject it off hand, despite the fact that it can be used > to recreate every prediction of relativity. I didn't say that the picture was absurd, and nor have I rejected it out of hand. It seems to me that one of the essential features of the theory is the need to account for propagation delays, but I keep getting told that it isn't, yet the only alternative explanation I'm given is that relativity reflects something "more real" than "mere propagation delays". So I've really just put the question into abeyance for now while I try to build some sort of consistent picture of how light behaves (which of course is what I'm doing on the thread "Known physics defeated..."), and I'm hoping that the pieces will eventually fall into place. > There's not that much > that needs to be interpreted in that picture. it means exactly what > it says it means, literaly--not in some abstract sense. Literally > think of a 4 dimensional space with that rotated rod in it. It was > not meant as a metaphor. As I say, it's something that I'll just have to put in abeyance for now. > > > It represents rotation, just like when I tell you that I rotated a > > > pole, that also represents a rotation. You just don't understand that > > > the two things are the same. You insist that they must be different > > > but in reality, they are not. They don't look quite the same to you > > > because of your perspective. It's exactly like the flatland example I > > > gave before. If you have people that live on a little, flat world > > > sitting in our 3 dimensional space, who can only percieve the things > > > that exist inside of their little 2 dimensional world, when something > > > rotates into that third dimension, they'll go "what the heck just > > > happened? That doesn't look like any rotation I've ever seen." > > > But there is no such thing as a two-dimensional "flatland" in reality. > > This is much like saying "imagine a place that is not real with people > > who are not real, and imagine what reality would look like to those > > people" (which I can only say is unimaginable), and then using this as > > some sort of proof of a "hidden reality" that is not apparent to > > people who *are* real. As I say, the four dimensions have been with us > > since the beginning of time, and people have in one way or another > > recognised their physical existence since the beginning of time. > > I don't think I can get you to visualize a 4 dimensional space, so I > took a 3 dimensional slice of 4 dimensions. I visualise 4D simply as 3D but with change - a bit like an animation, I suppose. But information also travels instantly in this visualisation, because I play the part of God, not of the human observer. > There's nothing invalid > about that. It's like looking at a building from the side and drawing > a 2 dimensional profile. But again, the 2D representation only means something because it can be translated into a 3D object. That's why every now and again you look at something and can't make sense of it until you identify the perspective and the nature of the objects depicted. 2D makes sense *precisely because* it can be translated into meaningful 3D objects. > In this case, we're looking at the universe > by taking a 3 dimensional slice--just a different 3 dimensional slice > than the one we're used to looking at. As I say, I can do 2D with time in my head. It just acts like a piece of paper, with the shapes moving. Or, if you wanted extra realism, you can build the pages up into a block of paper, and each level of the block represents a point in time, and if you remove/dissolve/make the paper transparent, then the 2D shapes build into 3D shapes. And if, for example, you had a 2D square moving spatially at a constant speed, then from a certain perspective it would make a trapezoid shape when formed into 3D. Of course, I can then understand this in terms of the shape becoming "shorter in space and longer in time", if we take that trapezoid and rotate it in time, so that the "points" of the trapezoid extend further into time, and the length of the shape contracts. But then I think to myself, space isn't 2D. But what sees only in 2D? The eye (or the camera, or whatever). And it becomes very convenient to view each "timeslice" as representing "what is visually observed". And believe it or not everything falls into place - relativity describes what is observed. > > > > > The picture I made for you wasn't supposed to represent an analogy--it > > > > > was supposed to represent physical reality (except with a slightly > > > > > different metric--but we don't need to worry about that just yet).. > > > > > If you don't recognise geometry as being an abstract *representation* > > > > of the physical world, as opposed to the physical world itself, then > > > > that is a clear difference in our understandings - and it's a > > > > philosophical difference which will not be reconcilable. > > > > It's no more or less geometry that showing you a picture of a pole > > > that's rotated in our regular 3 dimensional space. It's no more > > > abstract than that. Why do you insist on calling it something more > > > abstract than that? The picture I showed you is exactly the same > > > thing. > > > > Relable the axes x and y, instead of x and t. Now can you agree that > > > it's simply a picture of a rotated pole? Now, suddenly if I switch > > > the axes back to x and t, does it magically become more abstract just > > > because I changed the labels? > > > No, both are abstract. The difference is that a rotation in the y-axis > > translates into something quite physically different than a rotation > > in the t-axis. > > No, it doesn't. Take the picture exactly at face value. There is no > metaphor involved--it doesn't translate into anything other than what > the picture shows. Your problem is you're looking at the picture and > saying, "ok, on x and y, this is a rotation--exactly what it shows in > the picture," and then saying "ok, x and t, what does this mean in the > real world?" instead of saying, "ok, x and t, this is a rotation-- > exactly what it shows in the picture." Do not try to find some hidden > layer of interpretation. It is simply a "snapshot" of a 2 dimensional > slice of the universe. It doesn't matter what axis we take this slice > along. It does not represent anything different. I'm afraid we'll have to disagree. There is no argument that you make which will convince me that it is not necessary to ask "what does this mean in the real world". |