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 27 Feb 2010 08:00 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:2726fc2b-b860-4c84-96a9-3776df684de4(a)e7g2000yqf.googlegroups.com... > 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. > What's wrong with Minkowski space-time? It gives me and lots of other people a very clear conceptual model of SR. > > >> 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). That was not my argument. But I still don't get what your problem is with the conceptual model of SR provided by Minkowski space-time? It is isomorphic to SR, uses only simple geometry, and all the key equations of SR become simple geometric constructs. Minkowski contributed nothing to SR except a superb conceptual model, apparently exactly the thing you want. So why not learn it?
From: Jerry on 27 Feb 2010 08:42 On Feb 27, 7:00 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > 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). > > That was not my argument. > > But I still don't get what your problem is with the conceptual model of SR > provided by Minkowski space-time? It is isomorphic to SR, uses only simple > geometry, and all the key equations of SR become simple geometric > constructs. Minkowski contributed nothing to SR except a superb conceptual > model, apparently exactly the thing you want. > > So why not learn it? You should give Ste a specific book recommendation: Spacetime Physics, by Taylor and Wheeler The second edition can generally be picked up used for about $25. The first edition is frequently found on eBay with a "Buy it now" price of $5 to $10. To Ste: I actually prefer the first edition. It is a relatively thin, large format paperback that is deceptively easy to skim through without understanding. It is not a book for skimming. It has lots of problems with solutions, and the only way to truly learn the subject is to WORK THE PROBLEMS!!! None of the problems uses advanced math. If you can work the problems and get the correct answers, only then will you really understand what relativity is all about. As Peter pointed out, Minkowski spacetime is a superb conceptual model, and not at all difficult to understand provided that you take the time to learn it properly. There is no shortcut to learning how to do the math. But the math is simple! Jerry
From: Androcles on 27 Feb 2010 09:17 "Jerry" <Cephalobus_alienus(a)comcast.net> wrote in message news:ed4a3f66-304c-474b-88e7-5ac987bdbd3d(a)d2g2000yqa.googlegroups.com... On Feb 27, 7:00 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > 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). > > That was not my argument. > > But I still don't get what your problem is with the conceptual model of SR > provided by Minkowski space-time? It is isomorphic to SR, uses only simple > geometry, and all the key equations of SR become simple geometric > constructs. Minkowski contributed nothing to SR except a superb conceptual > model, apparently exactly the thing you want. > > So why not learn it? You should give Ste a specific book recommendation: Spacetime Physics, by Taylor and Wheeler The second edition can generally be picked up used for about $25. The first edition is frequently found on eBay with a "Buy it now" price of $5 to $10. To Ste: I actually prefer the first edition. It is a relatively thin, large format paperback that is deceptively easy to skim through without understanding. It is not a book for skimming. It has lots of problems with solutions, and the only way to truly learn the subject is to WORK THE PROBLEMS!!! None of the problems uses advanced math. If you can work the problems and get the correct answers, only then will you really understand what relativity is all about. As Peter pointed out, Minkowski spacetime is a superb conceptual model, and not at all difficult to understand provided that you take the time to learn it properly. There is no shortcut to learning how to do the math. But the math is simple! Jerry ===================================================== So simple that it's pathetic enough to treat time as if it were a vector as if it were magic. You should give Ste a specific book recommendation: Harry Potter and the Philosopher's Stone, by J. K. Rowling. The second edition can generally be picked up used for about $2.50. The first edition is frequently found on eBay with a "Buy it now" price of $1 to $2. To Ste: I actually prefer the first edition. It is a relatively thin, large format paperback that is deceptively easy to skim through without understanding. It is not a book for skimming. It has lots of problems with solutions, and the only way to truly learn the subject is to WORK THE PROBLEMS!!! None of the problems uses advanced math. If you can work the problems and get the correct answers, only then will you really understand what magic is all about. As the fuckwit pointed out, magical physics is a superb conceptual model, and not at all difficult to understand provided that you take the time to believe in nonsense. There is no shortcut to learning mathematics, take a course in vector algebra.
From: PD on 27 Feb 2010 10:46 On Feb 26, 6:46 pm, Ste <ste_ro...(a)hotmail.com> wrote: > 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. I'm not sure I buy the argument that anything should be fundamentally understandable to a child.
From: PD on 27 Feb 2010 10:54
On Feb 26, 6:54 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 26 Feb, 17:34, PD <thedraperfam...(a)gmail.com> wrote: > > > On Feb 25, 9:05 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > I also doubt one exists at the moment, but I see that as a problem. > > > It's utterly irreconcilable, within any conceptual framework that I > > > know of, to have situations where, for example, a large ladder can end > > > up in a smaller barn according to an observer stationary in the barn, > > > but not according to an observer riding the ladder. > > > Why? And here we can systematically trace back to the assumptions you > > are making and then question them. In this case, you have a firm > > belief that length is definable in such a way that it is intrinsic to > > the object and frame-independent, and that physical "fitting" is a > > function of the *intrinsic* lengths of two objects (or an object and a > > container). > > 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. I don't know what basis you have for judging whether something is "realistic". I'm guessing that it means that it is consistent with your intuition, and that your intuition tells you that something cannot fit in one frame and not fit in another, or that two events are simultaneous in one frame and not simultaneous in another. If this is accurate, then I would ask on what basis you trust your intuition. Or, even more aptly, why do you trust your intuition so much that you rule out other possibilities as real if they conflict with your intuition? > If > such a thing appears to happen, then it is obviously an artefact of > subjective observation. I disagree. In science, if there is a conflict between experimental observation and intuition, then it is *intuition* that becomes suspect, not the experimental result, especially if the latter is confirmed independently and by complementary means. This is basic in science. The principle at work is this: 1. Nature behaves a certain way consistently, because the rules of nature are consistent. 2. There is a way to make a measurement and account for biases so that what you are measuring is in fact the "real" behavior exhibited by nature. 3. The way to tell if you've succeeded in (2) is to make the measurement by complementary means, and by independent investigators. If both measurements have had the biases properly corrected, then the two results will agree. This confidence increases when additional measurements are made. 4. Once it is established that the experimental result is the underlying behavior truly exhibited by nature, and that the measurements all consistently measure that behavior, then there is no arguing with nature. If what nature exhibits is contrary to our expectations, then it is our expectations that are amiss, not nature. > > > > > Your disbelief of SR stems from the fact that you don't understand it. > > > > My disbelief, really, stems from the blatant lack of conceptual > > > understanding of the theory. I mean, as I repeatedly point out, I > > > don't know a single equation of relativity, and yet I can root out the > > > conceptual contradictions immediately when people here have a crack at > > > making meaningful qualitative statements in SR. The classic example, > > > of course, was Paul's contention that "what is simultaneous in one > > > frame can never be simultaneous in another", which of course isn't > > > true according to SR. > > > I'm sorry? It is very much true in SR that two spatially separated > > events that are simultaneous in one frame are not simultaneous in > > another frame moving relative to the first. > > But I contradicted that when I pointed out that two observers can be > moving relative to each other, and yet undoubtedly events can be > simultaneous for both. Not spatially separated ones, no. > I seem to remember you conceded that point when > I gave you a situation where it was true. |