A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: PD on 26 Feb 2010 13:17 On Feb 26, 1:21 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 26 Feb, 06:37, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: > > > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > > On 25 Feb, 09:46, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > > > wrote: > > >> And indeed, I said openly that I couldn't make that work, once I'd > > >> been able to construct a graphic where I could see the proof with my > > >> own eyes, and clearly the physical understanding on which that was > > >> based is untenable. As it stands, I don't really have any workable > > >> physical model for light under relativity. > > > >> _________________________________ > > > >> Relativity does not provide a workable physical model for light, in fact > > >> it > > >> says nothing about it at all. > > > >> The workable physical model for light is provided by Maxwell's eqns, > > >> which > > >> tell us *exactly* what light is; it is two out of phase electric and > > >> magnetic fields, and this uses the same maths and mechanisms as explain > > >> radio broadcasting, transformers, generators etc. > > > > You know I actually got as far as reviewing Maxwell's equations before > > > I started to fall over laughing at my gullibility. I really should > > > have realised at the outset that "Maxwell's equations" were not going > > > to involve anything physical. > > > You don't think electric and magnetic fields are physical? > > I was alluding to the "equations" bit. In any event, I think the > conceptual foundations of the electric and magnetic fields seems a > little unclear. Again, unclear to YOU. It is presumptuous to imagine that if you do not find them clear, then they are inherently unclear. > > > > And incidentally, after realising this, but before responding, I > > > actually scrolled down through the posts and found that Paul Stowe had > > > also made exactly the same argument. > > > You are therefore not alone in your ignorance. > > Touche. I personally fear for those who are not alone in their hubris > > > > > >> Most importantly, Maxwell's eqns are said to give rise to light waves, > > >> but > > >> these are fundamentally different what you think of as a wave. In water > > >> waves, there is a single variable - water height - and the wave exchanges > > >> energy with the medium through which it travels. Similarly with sound > > >> waves, > > >> where it is air pressure. In Maxwell, there are two waves always > > >> generated, > > >> the electric and the magnetic. The electric increases, it draws energy > > >> from > > >> the magnetic, the magnetic runs out, the electric collapses which feed > > >> energy into the magnetic, and so on ... multiply this by about 10^20 in > > >> speed and you have light. > > > > This is a bit wooly. Obviously there is some sort of oscillation going > > > on, but I suspect more work needs to be done on the concept. > > > Some more work has been done on the concept. About a 150 years worth. Its > > exactly how radio and TV transmitters work. You do concede that they do > > work, right? And that radio is a form of light? And radio waves can be made > > by simply oscillating electric and magnetic fields? > > > Just because you *nothing* about Maxwells eqns doesn't mean they need more > > work. It means you need to do more work, to bring your knowledge of physics > > up to where it was in the mid 19th Century. > > I think you misunderstand. I concede that light comprises some kind of > oscillation, and that many of its manifestations are well-understood, > but it seems to me (from what I've read) that it's conceptual basis is > a bit suspect. > > > > > >> The total energy of the photon/wave is constant, it simply exchanges > > >> energy > > >> between its electric and magnetic fields. If you ask what the electric > > >> wave > > >> is "waving through" - what is storing its energy as it goes up and down > > >> like > > >> a water wave - its the waves magnetic field, and the waves magnetic field > > >> is > > >> similarly beating against the electric field. This means there is no > > >> connection to any underlying medium which is waving, like in a water > > >> wave, > > >> it is self contained. This is ultimately why it has a Lorentz transform, > > >> and > > >> if you do the maths on Maxwell's equations you actually get the Lorentz > > >> contraction popping out automatically. The Michelson Morley experiment > > >> was > > >> specifically designed to compare the transforms for light and a physical > > >> object, and contrary to your opinion that physicists don't know how to > > >> design tests, was deliberately testing to the limits the prevailing > > >> understanding at that time, and found it to be wrong. > > > >> The rest is now over 100 years of history; you are a little late to find > > >> a > > >> problem. > > > > Lol. Perhaps a mistake more than 100 years ago is why there hasn't > > > been much theoretical or conceptual advance in 100 years? > > > Well, there was huge advance made when this was reformulated for > > non-inertial frames of reference in GR. > > > But the reason that SR has survived unchanged for 100 years is the same > > reason that Newtonian mechanics survived unchanged for 300 years - as far as > > we can tell with current measuring equipment, it works perfectly. > > Indeed. I suppose technologically there still plenty of shelf-life in > relativity.
From: PD on 26 Feb 2010 13:20 On Feb 26, 1:31 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 26 Feb, 06:00, "Inertial" <relativ...(a)rest.com> wrote: > > > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > >> > > I'm sorry, but in my mind there's a big difference between "adding > > >> > > detail to the picture" and "showing that the picture is self- > > >> > > contradictory". > > > >> > But you didn't show that it was contradictory. All you did was further > > >> > constrain the relationship between gravity and distance. > > > >> Oh, please. You said that a linear fall-off of gravity with distance > > >> was perfectly compatible with your mental image of gravity. But it > > >> ISN'T, because there are unexplored implications of those permitted > > >> assumptions that lead to contradictions. This is more than a detail > > >> refinement. > > > > I'm afraid it isn't Paul. I'm not so sure that this won't go anywhere > > > except just go back to what we agreed at the beginning, that my model > > > makes no firm predictions and is virtually unfalsifiable, and yet it > > > works > > > In what sense can it be said to work if it doesn't predict what is observed. > > It does predict what is observed, but only in a very loose way, No. It *accommodates*, it does not *predict*. And this is where there is a difference. It is one thing to say that a certain behavior is *conceivable* within a mental picture, it is another thing entirely to say that it is *demanded* from a model. A prediction is usually precise enough where it will be able to say, "you will see behavior X in quantity Qx, behavior Y in quantity Qy, and behavior Z in quantity Qz, but you will NEVER see behavior W and you will not see behavior Z in any other quantity." This your mental picture does not do. > and > really acts as the underpinning for further investigation or > refinement. Of course, philistines like yourself would look at a work > of art, and say "is the frame really necessary", "is the colour really > necessary", "is paint really necessary", and once all that is gone, > point out that there is nothing meaningful left. But of course while I > don't denigrate a mathematical formulation, there certainly seems to > be a great deal of denigration amongst physicists towards the physical- > conceptual aspects of their subject.
From: Ste on 26 Feb 2010 19:40 On 26 Feb, 12:31, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > About this gravity thing. I am having a great deal of difficulty forming a > mental picture of how it is supposed to work. At a fundamental level, I do too. > If the planets are separated > by vacuum, how could one object possibly pull on another object when there > is nothing between them? For that matter, how does one particle manage to > pull on every other particle in the Universe at the same time? Are you > positing some array of invisible springs, 10^160 of them, connecting the > 10^80 particles in the Universe? I think a more credible argument is that there *is* in fact something in between the objects. > Frankly, I find the suggestion that each time I move my finger to type these > invisible gravity springs cause every other particle in the Universe to move > ludicrous. Apart from anything else, how is this spooky action at a distance > supposed to work, physically? Springs and levers? What is gravity supposed > to be, physically? I don't find it hard to believe that every movement of the finger could have an effect on every other particle of the universe. In terms of what gravity is and how it works, that remains to be explained.
From: Ste on 26 Feb 2010 19:42 On 26 Feb, 12:50, "Inertial" <relativ...(a)rest.com> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > >> > I agree, but as I say I don't see how my model can be deemed as "not > >> > physics". > > >> Can you give me some details of your model. . this thread is too long to > >> go > >> back through it and try to find where you may have explained it > > > I've been more detailed in the past, but it basically just involved > > planets, orbits, and an attractive gravity force that had some > > relationship with distance. > > So you can't or won't give detail. OK .. fine. Well there wasn't a great deal more essential detail than that, although I might have included concepts like inertia.
From: Ste on 26 Feb 2010 19:46
On 26 Feb, 12:52, "Inertial" <relativ...(a)rest.com> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > Of course I'm not claiming to know anything profound about the solar > > system. The conceptual model has been accepted for centuries, and I'm > > not pretending to add anything new to it. The point I was making about > > it is that the conceptual model is required to give any real meaning > > to the equations. > > We already have such model .. that's the whole POINT of physics .. it is > modeling reality. How reality behaves is the meaning to the equations ... > they describe what is going on. Then show the equations to a child. Ask him if he understands what is going on. And remember, you're not allowed to mention the conceptual aspect, or appeal to sensory perception. You must only use the equations. If these equations alone describe what is going on meaningfully, then the child ought to understand immediately. |