A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Ste on 27 Feb 2010 05:06 On 27 Feb, 07:02, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:f1c82fe9-c833-4262-9bca-d62d9181c8b0(a)i39g2000yqm.googlegroups.com... > 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. > > ___________________________________ > Why a child? > > Why not try and explain the equations of SR to a nematode worm? If they > really do encompass SR, then the nematode worm should understand SR > immediately. Or so your logic would suggest. No, my logic wouldn't suggest that. My logic says that these equations are meaningless without a conceptual model that gives them meaning. > Here are the facts. To fully understand SR, you need to be reasonably > intelligent, have a basic maths ability, and have some knowledge of physics. > > A child, a nematode worm, and yourself all miss out on some or all of these. > > If you want to understand SR, you are going to need to learn some maths and > physics. Some things actually require work. Sorry. You can teach the child maths. But you can't tell him anything about the nature of the universe (because otherwise you're providing the conceptual model by the back door, when it is your argument that this is not necessary to understand physics, only the maths is required).
From: Peter Webb on 27 Feb 2010 07:15 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:24fcda5b-da02-4f35-bb34-2ad7f368d399(a)t23g2000yqt.googlegroups.com... > On 27 Feb, 05:50, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: >> > My only contention is that it is *not realistic* to say that from the >> > barn frame frame the ladder contracts and fits inside, while saying >> > that from the ladder frame it is the barn that contracts and the doors >> > actually never shut simultaneously. It is simply not realistic. If >> > such a thing appears to happen, then it is obviously an artefact of >> > subjective observation. >> >> Better not tell GPS units, particle accelerators, space probes, or light >> from distant stars that length contraction is not realistic, or they >> might >> all suddenly decide not to undergo length contraction, with obvious huge >> problems for navigation, particle physicists, astronomers etc all of whom >> rely upon things behaving in a not realistic manner which you don't >> understand for correct operation. > > Why? If we assume that GPS satellites (or whatever) are taking the > position of "subjective observers", Whatever that means. > then there is absolutely no > problem. The point, perhaps, is that there is more to relativity than > meets the eye. Your eyes, certainly. You know almost nothing about it.
From: Peter Webb on 27 Feb 2010 07:19 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:c12d7ec0-bd6d-44a0-941a-c5c31cc02c71(a)g28g2000yqh.googlegroups.com... On 27 Feb, 05:54, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Paul Stowe" <theaether...(a)gmail.com> wrote in message > > news:73c93327-144e-4595-ada1-4bfff749884c(a)e19g2000prn.googlegroups.com... > On Feb 26, 5:00 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 26 Feb, 18:20, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Feb 26, 1:31 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > 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. > > > But it does for example. My mental picture says that gravity will > > never become stronger with increasing distance. That is a firm > > prediction. > > But, in both the center of a spiral galaxy and the center of mass the > gravitational potential is zero, increasing in strength until one > reaches either the surface of a solid planet or, in the case of a > galaxy the rotation speed verses area density starts to drop off. So, > while I understand where you are coming from, technically, you're > wrong. > > _____________________________ > In fact, the earth's gravity increases for a period as you go further > underground. As you said, the exact opposite of the only prediction we > have > heard from the model. The Earth's gravity increasing as you go underground I presume is due to density layers. In any event, this is not the "exact opposite" of the prediction, because the idea of having two planets "go underground" towards each other's centres is absurd - we were, after all, discussing a conceptual model of the solar system. ________________________________ Here is what you said in full, as shown above: "But it does for example. My mental picture says that gravity will never become stronger with increasing distance. That is a firm prediction." I know you'll say "ah, you're just making it up as you go along", but we both accept I knew this fact (not least because I'd asked the question on this group previously, about exactly how gravity drops off as one goes underground into a spherical mass, and it was discussed at some length), but once again instead of being sensible you seize on a statement which was not tailored towards addressing this specific point. _______________________________ It is the *only* property you ascribed to gravity in your model. Interesting its wrong.
From: Ste on 27 Feb 2010 07:36 On 27 Feb, 12:19, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > But, in both the center of a spiral galaxy and the center of mass the > > gravitational potential is zero, increasing in strength until one > > reaches either the surface of a solid planet or, in the case of a > > galaxy the rotation speed verses area density starts to drop off. So, > > while I understand where you are coming from, technically, you're > > wrong. > > > _____________________________ > > In fact, the earth's gravity increases for a period as you go further > > underground. As you said, the exact opposite of the only prediction we > > have > > heard from the model. > > The Earth's gravity increasing as you go underground I presume is due > to density layers. In any event, this is not the "exact opposite" of > the prediction, because the idea of having two planets "go > underground" towards each other's centres is absurd - we were, after > all, discussing a conceptual model of the solar system. > > ________________________________ > Here is what you said in full, as shown above: "But it does for example. My > mental picture says that gravity will never become stronger with increasing > distance. That is a firm prediction." > > I know you'll say "ah, you're just making it up as you go along", but > we both accept I knew this fact (not least because I'd asked the > question on this group previously, about exactly how gravity drops off > as one goes underground into a spherical mass, and it was discussed at > some length), but once again instead of being sensible you seize on a > statement which was not tailored towards addressing this specific > point. > > _______________________________ > It is the *only* property you ascribed to gravity in your model. Interesting > its wrong. You're just being obtuse Peter. If I wanted to be stubborn, I could point out that a spherical mass like a planet is in fact an aggregation of particles, and the increasing gravity (as one ascends to the surface of a spherical mass) is a function of that aggregation, rather than a fundamental behaviour of gravity. In that way, the basic premise as stated remains tenable, which is that gravity falls off with distance.
From: Peter Webb on 27 Feb 2010 07:53
"Ste" <ste_rose0(a)hotmail.com> wrote in message news:f47fb4af-7f73-420b-b61b-73a4ce42b1e5(a)q15g2000yqj.googlegroups.com... > On 27 Feb, 06:55, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> news:2268f44a-518e-43b4-a3f8-a610f4e89e89(a)o30g2000yqb.googlegroups.com... >> >> >> >> >> >> > 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. >> >> Ohhh, so your mental model of the solar system contains "gravity", yet >> your >> mental model of the solar system provides no physical explanation of what >> it >> "really" is. >> >> Funny, you complained about SR and Minkowski for having components for >> which >> you have no physical model. Yet your own theory of the solar system >> contains >> concepts such as gravity which have no physical explanation at all within >> the model. > > Yes, but I readily concede this, and accept that there needs to be > work done to find out what gravity actually is. For the time being, I > have a model that operates at a macro level, where gravity is assumed > to be a fundamental manifestation of reality. Yet you speak as though > I've let the cat out of the bag or something. > So you have no *physical* idea of what gravity really is, but that doesn't stop you using it in a model. Funny, the fact that SR contains things which you have no *physical* explanation of was a huge problem for SR, but the same problem doesn't worry you for your own model. > > >> Newton's theory of gravitation and SR are not at all different in that >> respect. Newton's theory of gravity says nothing at all about what >> gravity >> "really" is. SR says nothing about what length contraction "really" is. >> The >> theories don't need to. The equations all work; the rest is philosophy. >> In >> your case, bad philosophy. > > And you're an idiot if you think anything other than equations is > "philosophy, not physics", and you typify the explanation for why > theoretical physics won't move an inch until your kind are steadily > retired out of the dominant positions in academia. Theoretical physics is doing quite well without your advice, thanks all the same. |