A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: bert on 15 Feb 2010 17:03 On Feb 13, 3:24 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 13, 1:43 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 13 Feb, 19:11, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Feb 13, 1:01 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 13 Feb, 18:45, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > On Feb 13, 11:51 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > Not really. I'm still struggling to understand what is happening > > > > > > physically to explain these phenomena (which is not helped by the > > > > > > dearth of interest in physics in physical, rather than mathematical, > > > > > > explanations). > > > > > > Oh, come now. You appear to have bailed on the discussion of > > > > > relativity of simultaneity, which I was doing with purely physical > > > > > explanations and a complete lack of math. > > > > > I think you're being just a bit disingenuous here. > > > > > I didn't bail on it. I said I felt that your train analogy had a lot > > > > of extraneous concepts, such as clouds and tracks, > > > > On the contrary, I *agreed* with you that the clouds (which I never > > > brought up -- you did) are extraneous, as are the tracks, which is > > > precisely why the velocities of the train with respect to the tracks > > > are irrelevant. > > > Indeed, and that is where the analogy ended as I recall. > > > > > and then you didn't > > > > really go on to say anything more about that analogy or about > > > > simultaneity. > > > > I'm sorry, read again. I laid out the plan for where we were going > > > next. Did you not see that? > > > I did read it again before replying to you, to make sure I hadn't > > missed anything. I couldn't see your response to me that dealt with > > the analogy any further. > > Here is where I think we last left things:http://groups.google.com/group/sci.physics/msg/26e91b6493e277e1? > andhttp://groups.google.com/group/sci.physics/msg/4a126a6622bac8b1- Hide quoted text - > > - Show quoted text - Photons do not change speed. They do not bounce, Think change only distance TreBert
From: kenseto on 15 Feb 2010 17:03 On Feb 15, 4:06 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 15, 2:38 pm, kenseto <kens...(a)erinet.com> wrote: > > > > > > > On Feb 15, 12:27 pm, mpalenik <markpale...(a)gmail.com> wrote: > > > > On Feb 15, 6:54 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 14 Feb, 23:46, mpalenik <markpale...(a)gmail.com> wrote: > > > > > > On Feb 14, 2:03 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > I'm afraid you're easily satisifed Tom. As I say, I'm not really > > > > > > interested in learning geometry, or talking about completely > > > > > > hypothetical "grooves in spacetime". > > > > > > And as many people have repeatedly tried to explain to you, the answer > > > > > simply is geometry. When you accellerate, you rotate in spacetime. > > > > > Why? Because that's what accelleration means. That's what it means > > > > > to be travelling with a certain velocity with respect to something > > > > > else. It means that you're both "facing different directions". Every > > > > > effect predicted by relativity can be explained simply by the fact > > > > > that two different observers at different speeds are "facing different > > > > > directions" in spacetime--because that's what it means to be moving > > > > > with respect to something else. It means that you have a different t > > > > > and x axis. > > > > > Mark, if you consider this an answer, then you simply haven't > > > > understood the question.- Hide quoted text - > > > > > - Show quoted text - > > > > And if you think there's more to it than that, then you haven't > > > understood the answer. The above explains everything about relativity > > > and there's no ambiguity when you understand it. > > > > Going back to the fitting a ladder into a barn analogy, it's like you > > > have a ladder to long to fit into the barn, you turn it at an angle, > > > and it fits, and then someone starts asking you what "physically" > > > happened to the ladder. You say "well, it got rotated, so it's > > > shorter in the horizontal direction". Then the person keeps demanding > > > a physical explanation, and you say you just rotated the ladder, so it > > > takes up a bit more space in the vertical and less in the horizontal > > > but the total length of the ladder didn't change. > > > In this case you are not fitting the length of the ladder through a > > narrow door way. You are fitting a skinny side of the ladder through a > > wider door way. > > This is not the same as an 80 ft long material pole can fit into a 40 > > ft long material barn with both doors close simultaneously. In this > > case material contraction must occur. That's thee reason why modern > > interpretation of length contraction in Sr is merely a geometric > > effect instead of material or physical effect as asserted by the > > runts of the SRians such as PD and you. > > "Material" does not mean the same thing as "physical", Ken. > This has been pointed out even in the common dictionary. > If you can't let go of your mistakes, Ken, you'll never get off square > one. Physical is material....is one of the definitions in my dictionary. > > > > > > > Ken Seto > > > > And then the person > > > you're talking to says that he refuses to believe that mathematical > > > things like angles can affect the things that you can put the ladder > > > inside of So then, you try to say that it's like trying to pack a box > > > and turning all of the objects so they fit into the box the best way. > > > And then he says "well, there's no doubt that rotating objects is > > > useful for packing boxes but it doesn't explain what physically > > > happened to the ladder," so you try to explain one more time and he > > > says you didn't understand the question. And when you tell him that > > > you can even *calculate* the length and height of the ladder after > > > rotating it, he says that's an abstract mathematical question and has > > > no bearing on what's physically happening. > > > > Velocity is rotation, just rotation in a way that you're not used to > > > being able to rotate. There's nothing else to explain. You > > > accellerate something, it rotates. That's a physical answer. - Hide quoted text - > > > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -
From: Inertial on 15 Feb 2010 17:16 "kenseto" <kenseto(a)erinet.com> wrote in message news:65b0b432-ea12-4f62-8dea-14b916d28a20(a)15g2000yqi.googlegroups.com... > On Feb 15, 4:06 pm, PD <thedraperfam...(a)gmail.com> wrote: >> On Feb 15, 2:38 pm, kenseto <kens...(a)erinet.com> wrote: >> >> >> >> >> >> > On Feb 15, 12:27 pm, mpalenik <markpale...(a)gmail.com> wrote: >> >> > > On Feb 15, 6:54 am, Ste <ste_ro...(a)hotmail.com> wrote: >> >> > > > On 14 Feb, 23:46, mpalenik <markpale...(a)gmail.com> wrote: >> >> > > > > On Feb 14, 2:03 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> > > > > > I'm afraid you're easily satisifed Tom. As I say, I'm not >> > > > > > really >> > > > > > interested in learning geometry, or talking about completely >> > > > > > hypothetical "grooves in spacetime". >> >> > > > > And as many people have repeatedly tried to explain to you, the >> > > > > answer >> > > > > simply is geometry. When you accellerate, you rotate in >> > > > > spacetime. >> > > > > Why? Because that's what accelleration means. That's what it >> > > > > means >> > > > > to be travelling with a certain velocity with respect to >> > > > > something >> > > > > else. It means that you're both "facing different directions". >> > > > > Every >> > > > > effect predicted by relativity can be explained simply by the >> > > > > fact >> > > > > that two different observers at different speeds are "facing >> > > > > different >> > > > > directions" in spacetime--because that's what it means to be >> > > > > moving >> > > > > with respect to something else. It means that you have a >> > > > > different t >> > > > > and x axis. >> >> > > > Mark, if you consider this an answer, then you simply haven't >> > > > understood the question.- Hide quoted text - >> >> > > > - Show quoted text - >> >> > > And if you think there's more to it than that, then you haven't >> > > understood the answer. The above explains everything about >> > > relativity >> > > and there's no ambiguity when you understand it. >> >> > > Going back to the fitting a ladder into a barn analogy, it's like you >> > > have a ladder to long to fit into the barn, you turn it at an angle, >> > > and it fits, and then someone starts asking you what "physically" >> > > happened to the ladder. You say "well, it got rotated, so it's >> > > shorter in the horizontal direction". Then the person keeps >> > > demanding >> > > a physical explanation, and you say you just rotated the ladder, so >> > > it >> > > takes up a bit more space in the vertical and less in the horizontal >> > > but the total length of the ladder didn't change. >> >> > In this case you are not fitting the length of the ladder through a >> > narrow door way. You are fitting a skinny side of the ladder through a >> > wider door way. >> > This is not the same as an 80 ft long material pole can fit into a 40 >> > ft long material barn with both doors close simultaneously. In this >> > case material contraction must occur. That's thee reason why modern >> > interpretation of length contraction in Sr is merely a geometric >> > effect instead of material or physical effect as asserted by the >> > runts of the SRians such as PD and you. >> >> "Material" does not mean the same thing as "physical", Ken. >> This has been pointed out even in the common dictionary. >> If you can't let go of your mistakes, Ken, you'll never get off square >> one. > > Physical is material....is one of the definitions in my dictionary. My dictionary says it is relating to the human body (as opposed to mind or spirit), or involving bodily contact. So if you mean length contraction in SR is not physical because it does not involve human body contact, then I'd agree. In any case, SR says the all the atoms of a moving rod are closer together (in the frame of a relatively moving observer). ie. that the spatial distance between them (at any given time) is shorter than when the rod is at rest. That sounds 'physically' shorter to me. But then .. you think that geometric things like rotation and translation are not physical .. so by your logic, when an object gets compressed, it is really just a geometric effect of the atoms translating closer together, but not a material change to the atoms themselves, so therefore it is not physical. You do realize that geometry is just a human model for what is happening 'physically' in reality (depending on which geometry you use .. you can have geometries that are not models of any reality we are aware).
From: mpalenik on 15 Feb 2010 17:48 On Feb 15, 3:38 pm, kenseto <kens...(a)erinet.com> wrote: > On Feb 15, 12:27 pm, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 15, 6:54 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 14 Feb, 23:46, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 14, 2:03 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > I'm afraid you're easily satisifed Tom. As I say, I'm not really > > > > > interested in learning geometry, or talking about completely > > > > > hypothetical "grooves in spacetime". > > > > > And as many people have repeatedly tried to explain to you, the answer > > > > simply is geometry. When you accellerate, you rotate in spacetime. > > > > Why? Because that's what accelleration means. That's what it means > > > > to be travelling with a certain velocity with respect to something > > > > else. It means that you're both "facing different directions". Every > > > > effect predicted by relativity can be explained simply by the fact > > > > that two different observers at different speeds are "facing different > > > > directions" in spacetime--because that's what it means to be moving > > > > with respect to something else. It means that you have a different t > > > > and x axis. > > > > Mark, if you consider this an answer, then you simply haven't > > > understood the question.- Hide quoted text - > > > > - Show quoted text - > > > And if you think there's more to it than that, then you haven't > > understood the answer. The above explains everything about relativity > > and there's no ambiguity when you understand it. > > > Going back to the fitting a ladder into a barn analogy, it's like you > > have a ladder to long to fit into the barn, you turn it at an angle, > > and it fits, and then someone starts asking you what "physically" > > happened to the ladder. You say "well, it got rotated, so it's > > shorter in the horizontal direction". Then the person keeps demanding > > a physical explanation, and you say you just rotated the ladder, so it > > takes up a bit more space in the vertical and less in the horizontal > > but the total length of the ladder didn't change. > > In this case you are not fitting the length of the ladder through a > narrow door way. You are fitting a skinny side of the ladder through a > wider door way. > This is not the same as an 80 ft long material pole can fit into a 40 > ft long material barn with both doors close simultaneously. In this > case material contraction must occur. That's thee reason why modern > interpretation of length contraction in Sr is merely a geometric > effect instead of material or physical effect as asserted by the > runts of the SRians such as PD and you. > > Ken Seto > Wow, SRian. . . that's a word that nobody in the real world uses. LOL--it's funny reading this group just for the ridiculous lingo the crackpots make up in an attempt to be insulting.
From: Ste on 15 Feb 2010 19:14
On 15 Feb, 19:37, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 15, 1:20 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > No, I'm saying that one should treat with utmost suspicion those who > > say the essential concepts of some theory cannot be understood in > > familiar everyday terms, and can only be understood within the terms > > of its own special language. > > I'm not sure why. It's a matter of economy. For example, when speaking > of rotation, you have in mind a *particular kind* of rotation -- a > spatial rotation -- because that's what so in everyday terms. But this > is a *special case* of what rotation means. Now, physicists have a > choice here: 1) They can cow to the everyday language and instead of > saying "rotation" they can say "generalized rotation which the > following broader meaning: [etc]" and repeating that phrase every time > they want to talk about rotation in general and not spatial rotations > in specific, lest someone get confused and think that "rotation" means > the same thing as the specific case; or 2) They can urge the reader to > broaden their understanding of the term "rotation" so that spatial > rotation thenceforth becomes recognized as the special case for the > reader as well, and so that "rotation" can be used to mean the > generalized term and "spatial" rotation" can mean the special case. > > There's a sound reason for preferring the latter, though it does pose > a learning curve for the reader. No I actually agree with you Paul. The use of the word "rotation" is perfectly legitimate in this context, to describe a geometric transformation. My argument is that those who claim knowledge here don't seem to emphasise strongly enough, when queried, that this geometric rotation into time bears *absolutely no resemblance at all* to the physical act of spatial rotation. > > I can understand "rotation" in geometric terms, and indeed I can > > immediately see how rotation into time involves no different a > > mathematical procedure than rotation in space. But in physical terms, > > it seems to me the differences are vast. > > And the differences between whales and tetrapod land mammals are vast, > even though in the abstract meaning of mammals, those differences > become ancillary details. > > And this is precisely the point -- the MEANING of "mammal" as > *properly* understood should make it apparent that the differences are > ancillary details, rather than huge and fundamental differences. Or > another way of looking it is that if someone thinks of mammals as > tetrapod land animals, using the specific class to mean the same as > the general term, and so that whales appear to be mammals "on paper > only" but obviously not of the familiar class of tetrapod land > mammals, then this person does not have a clear understanding of what > the term "mammal" means. I actually tend to avoid this sort of concrete classification - it only leads to trouble if you place strain on it. But even so, whatever physical characteristics mammals share in common, there is absolutely no common physical basis between spatial rotation and this alleged temporal rotation. Indeed time itself shares absolutely nothing physically in common with the 3 spatial dimensions. > > I'm not saying it meant either of those things. I'm just giving you an > > example of how you would describe something in terms of everyday > > language. Obviously, because you know the true nature of this > > "rotation into time" and I don't, then it's for you to describe (if > > you can and so wish to do so) the essential features in everyday terms. > > And that's the problem, you see. Everyday language attempts to > pigeonhole things that do not belong in any of the available > pigeonholes. This is the point that Feynman makes in "The Character of > Physical Law". Our everyday language categorizes physical things that > propagate into two disjoint categories: particles and waves. It is > therefore natural to ask, in everyday terms, whether so-and-so is a > particle or is a wave. Those are the only two available pigeonholes > from everyday experience. The problem is, we've learned that a large > group of physical things that propagate do not fall into either > category and have to be described by a new category. Yet, in an appeal > to everyday experience, this expansion opportunity is unavailable, as > there are only those two classes available from everyday experience. I'm not sure anyone has demanded that EM be either a particle or a wave. Indeed, I'd be open to any reasonable physical concept. But it's not good enough to say something is a particle and a wave, because those two things are mutually exclusive in physical terms. If something has both behaviours, then that's something that modern physics needs to explain coherently. > Yet, if we try to categorize any of these physical things as a > particle, we make mistakes, and if we categorize them as waves, we > make mistakes. There are things in nature, as Feynman says, that are > simply not like anything we've ever seen before, and so our everyday > categorizations and descriptions are simply insufficient. I'm ambivalent about Feynman. There's some things that I'd agree with him on, but this isn't one of them. I suspect there are some people who think very concretely in verbal terms (or even mathematically), and who need to learn to think a bit more vaguely and analogously, but I tend to consider my own understanding to be fluid enough already and my scepticism healthy, so I don't really need to be lectured about how my preconceptions are a bar to my understanding. As I've said, I can recognise that brilliant mathematicians are necessary for physics, but they are certainly not sufficient. |