A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: PD on 18 Feb 2010 11:08 On Feb 18, 9:56 am, "Simple Simon" <pi.r.cubed-nos...(a)gmail.com> wrote: > PD wrote: > > > The rest length of the rod is unchanged. Since this rest length is the > > length measured in only one frame (the rest frame), I'm reticent to > > call it an intrinsic property. > > Of two rods, the one with the greater rest length is "larger". Or, iif you > prefer, the set of possible lengths of the rod with greater rest length is > greater (and its supremum is its rest length). I like this operational definition.
From: PD on 18 Feb 2010 11:18 On Feb 18, 9:22 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > I don't hold that alternate dimensions are a real possibility, so of > course I don't accept that theories that employ them are credible. > > ____________________________ > > Well, firstly that is because you have no real idea of what a dimension is > in physics. Well, I don't know whether that's the case with Ste or not. What does seem to be true is that, whatever the meaning of dimension is, he would like to be able to *relate* that meaning to the meaning conveyed by the "everyday" usage of the word. This is what's full of peril. The example I've been using is "mammal" when the "ordinary man" might typify mammals with cows, dogs, apes, bears, giraffes. Such a mental concept becomes ensnarled with the features or context of land- dwelling creatures with four limbs. Then when whales are brought up, it becomes difficult to connect the word "mammal" with whales precisely because of the dissonance with land-dwelling, tetrapod creatures. This points out two problems. First of all, what makes a mammal a mammal is not clearly understood, since other extraneous baggage is being dragged in and is obscuring the essence of being mammalian. Secondly, it reveals the inherent unreliability of the mental strategy of trying to relate a general meaning to an "everyday" meaning, attractive though that might be. > > Also, you are not used to the mathematical representation of surfaces of > different dimensions being equivalent to equations, so you don't easily > "see" how dimensions pop out of Special Relativity as rotations - lets be > frank here, your knowledge of rotation matrices is pretty slim I'm guessing. > So you can't "see" whats going on because you are not sufficiently > mathematically sophisticated. > > Secondly, SR does not postulate any additional dimensions - just the four > normal one of three in space and on in time that probably even you have > noticed, its just that you think you have an orthogonal view; you don't, > your view is tilted by the speed you are going ... a fact quite easily > demonstrated by SR and proved a thousand times a day. > > If you are having trouble understanding the concepts of different > dimensions, read Flatland by Edwin Abbott. You will be relieved to hear that > it contains almost no mathematics in the sense you probably understand it, > but a great deal in a sense you don't.
From: mpalenik on 18 Feb 2010 11:32 On Feb 18, 9:32 am, JT <jonas.thornv...(a)hotmail.com> wrote: > On 18 Feb, 11:08, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 17, 2:14 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 17 Feb, 18:04, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 17, 12:51 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > On 17 Feb, 16:07, mpalenik <markpale...(a)gmail.com> wrote: > > > > > > > On Feb 17, 10:04 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > > > As we discussed earlier, it may be that we are only AWARE of four > > > > > > > > dimensions. It may well be that there are more. Then the way to > > > > > > > > entertain this notion is to ask the question, how would something that > > > > > > > > is only AWARE of two dimensions become convinced that there is a third > > > > > > > > dimension? This turns out to be very answerable. > > > > > > > > I'm afraid that was not my conclusion. As I've said, these > > > > > > > possibilities only seem credible to those who already hold them to be > > > > > > > credible. > > > > > > > Well, how could they seem credible to people who don't hold them > > > > > > credible? > > > > > > I fear the answer follows naturally from the question: they don't seem > > > > > credible, to people who don't hold them to be credible. > > > > > That is true by definition > > > > I know, which makes one wonder why you asked the question in the first > > > place. > > > I was trying to find out why you even made the statement in the first > > place. You might as well have said "the only people who are tall are > > the ones who aren't short."- Dölj citerad text - > > > - Visa citerad text - > > At least he do not use tall meters and short meters like you. Length > units can not be shorter and longer. > > Just as their can be no mutual timedilation time units can not be > shorter and longer because of their state of motion, the units remain > the same although there can be effects on the measuring equipment. > > JT > > JT The only reason I'm using tall meters today is because I ran out of my short meter sticks and the supplier couldn't send any new ones before I needed to measure something. But to convert tall meters to short meters you just divide by 1.5 anyway. It's when you use the super short meters that you run into trouble because nobody even knows where to buy the damn meter sticks to go with them, so the best you can really do it give it a guess.
From: mpalenik on 18 Feb 2010 11:35 On Feb 18, 9:43 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 18 Feb, 10:08, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 17, 2:14 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 17 Feb, 18:04, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 17, 12:51 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > On 17 Feb, 16:07, mpalenik <markpale...(a)gmail.com> wrote: > > > > > > > On Feb 17, 10:04 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > > > As we discussed earlier, it may be that we are only AWARE of four > > > > > > > > dimensions. It may well be that there are more. Then the way to > > > > > > > > entertain this notion is to ask the question, how would something that > > > > > > > > is only AWARE of two dimensions become convinced that there is a third > > > > > > > > dimension? This turns out to be very answerable. > > > > > > > > I'm afraid that was not my conclusion. As I've said, these > > > > > > > possibilities only seem credible to those who already hold them to be > > > > > > > credible. > > > > > > > Well, how could they seem credible to people who don't hold them > > > > > > credible? > > > > > > I fear the answer follows naturally from the question: they don't seem > > > > > credible, to people who don't hold them to be credible. > > > > > That is true by definition > > > > I know, which makes one wonder why you asked the question in the first > > > place. > > > I was trying to find out why you even made the statement in the first > > place. You might as well have said "the only people who are tall are > > the ones who aren't short." > > I'm confused Mark. > > My position is that someone must hold a priori that alternate > dimensions are a real possibility, in order to hold that any theory > that employs alternate dimensions is credible. Some here do hold that > alternate dimensions are a real possibility, so of course they hold > theories that employ them as credible. > > I don't hold that alternate dimensions are a real possibility, so of > course I don't accept that theories that employ them are credible. The problem is, you act like everybody in this group went into physics classes knowing and believing everything that was taught in the physics classes. The point is, your argument boils down to "the only people I see convinced of alternate dimensions are the people who believe in alternate dimensions," but that's a circular argument. The only way for that to hold water would be if the people who believe in them had always believed in them. Nobody is born knowing these things. We all had to learn and change our opinions at some point. If your argument is that there are some people who will never be convinced, I completely agree with that. There are also some people who will never be convinced of evolution. And you could make the same argument "the only people who believe in evolution are the people who believe in evolution." It's a circular argument and it means nothing.
From: mpc755 on 18 Feb 2010 11:39
On Feb 18, 2:30 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "mpc755" <mpc...(a)gmail.com> wrote in message > > news:8e724cb5-1db0-47c2-aa3d-5ed7150295ea(a)f15g2000yqe.googlegroups.com... > On Feb 18, 12:40 am, "Peter Webb" > > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > "mpc755" <mpc...(a)gmail.com> wrote in message > > >news:c7b417f4-cdc4-414a-a24c-3f2e7fc4c67d(a)t42g2000vbt.googlegroups.com.... > > On Feb 16, 11:55 pm, "Peter Webb" > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > > "mpc755" <mpc...(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? > > > Replace 'earth' with 'train' and read my responses if you want to know > > the answer. > > > ____________________________ > > So you refuse to answer (again). Shows how much confidence you have in > > your > > own theories. > > I have a great deal of confidence in my theory but why am I going to > waste my time having to go back through my posts and replace 'train' > with 'tabletop', or replace 'train' with 'Earth'? > > __________________________________ > Nobody is asking you to. I am asking you a very simple question about your > theory. Say the earth is moving at speed v relative to the ether. The speed > of light in the direction the earth is travelling is measured in a > laboratory on earth. What is its measured speed? > > If you think the clocks being moved on a moving tabletop or the clocks > being moved on the flat bed cars of a moving train makes a difference > then this 'conversation' is pointless. > > _________________________________ > There are in fact 4 possibilities: > > a) c > b) c+v > c) c-v > d) something else. > > You could just answer 'a', 'b', 'c' or 'd'. That is only typing a single > character; that's not too much work for you, is it? d) Something else. In order to understand the something else read my posts discussing the simultaneity of lightning strikes as determined by Observers on the train and on the embankment. |