Known physics defeated by simple puzzle?
in [Relativity]
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From: Ste on 7 Apr 2010 23:05 On 8 Apr, 00:13, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > On 7 abr, 17:39, Ste <ste_ro...(a)hotmail.com> wrote: > > > Like I said, the equations of audio Doppler predict that the received > > frequency will change depending on your velocity to the source. But it > > does not *explain* why this happens, and nor does it state whether the > > source frequency changes or not. All it describes is what you will > > observe, without *any* physical explanation at all. One must look > > *beyond* the mere maths of audio Doppler, in order to *physically > > explain* the effect. > > On the contrary, the mathematical model on that case does explain what > IT IS OBSERVED IN NATURE. But maths tells us nothing about what is real. It simply quantifies observations - it does not explain them. > You don't ask why the Earth, together with > the rest of the planets, move in a determined direction and not in the > opposite direction. I don't see why I wouldn't ask that. > > > and you > > > are just picking some so called "paradoxes" or in your language > > > "puzzles" to try to attack the model. > > > The truth is that I'm not "attacking" SR - in the sense of saying that > > it is inapplicable to reality. I'm actually arguing about *how* it > > applies to reality. > > Actually is quite clear, after over 2000 posts, It certainly feels like 2000 posts.
From: Inertial on 7 Apr 2010 23:09 "Sue..." <suzysewnshow(a)yahoo.com.au> wrote in message news:541c6f6d-a61d-4ea7-bf46-0c8e404289ec(a)11g2000yqr.googlegroups.com... > On Apr 7, 5:24 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> On 7 Apr, 15:49, "Inertial" <relativ...(a)rest.com> wrote: >> >> >> >> > "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> >news:cf5cd01b-0da3-41b0-88b5-69b2e678a011(a)z7g2000yqb.googlegroups.com... >> >> > > On 7 Apr, 05:08, "Inertial" <relativ...(a)rest.com> wrote: >> > >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> > >> >> > Again, hidden in the meaning here is 100km/h >> > >> >> > *relative to what*. An object cannot travel at *both* 100km/h >> > >> >> > *and* >> > >> >> > 50 >> > >> >> > km/hr *relative to me*. >> >> > >> >> I didn't say it could. But we are talking about things being >> > >> >> real.. >> > >> >> you >> > >> >> claim that all observers have to agree about the value for it to >> > >> >> be >> > >> >> real. >> >> > >> > Yes, I do say that! >> >> > >> So velocity is not real, momentum is not real, kinetic energy is not >> > >> real, >> > >> length is not real, time is not real etc etc. >> >> > >> Is that REALLY what you want to be saying? >> >> > > But I'm not saying that, am I? >> >> > By implication, yes, you are >> >> > > You're the one putting these words in >> > > my mouth. >> >> > No .. I am applying your definition. >> >> > If that is NOT what you want to be saying, then you should change yoru >> > definition >> >> No Inertial, you're not applying my definition, because you don't even >> understand my definition. > > We can't use your definition because Einstein's > definition puts the ballistic light that > W. deSitter never found on an imaginary axis. Umm .. no. There's no ballistic light required for SR. Only the time between light being emitted at the source and arriving at its destination gives a speed of c for all inertial reference frames. How it gets there is not really a matter for SR .. it is propagation method agnostic. OMG> Sue makes a quote that is actually on topic.... > <<There is only one demand to be made of the > definition of simultaneity, namely, that in > every real case it must supply us with an > empirical decision as to whether or not the > conception that has to be defined is fulfilled. > That my definition satisfies this demand is > indisputable. That light requires the same time > to traverse the path A �> M as for the path B �> M > is in reality neither a supposition nor a hypothesis > about the physical nature of light, but a stipulation > which I can make of my own freewill in order > to arrive at a definition of simultaneity.�>> > http://www.bartleby.com/173/8.html Of course, to be useful, such a 'stipulation' for simultaneity needs to be consistent, reflexive etc. Also note that the equal time required is indeed a direct consequence of the second postulate. That correctly synchronized clocks show those equal times as equal is almost self-evident. > The ballistic light only *appears* for people > of his time that applied Newtons mechanics to > light particles. > > http://en.wikipedia.org/wiki/Emitter_theory > > In the formal statement the ballistic > property vanishes. > > http://www.bartleby.com/173/17.html There was (and is) no need for ballistic light in SR. You seem confused that it ever did.
From: Inertial on 7 Apr 2010 23:12 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:d4ca2bc9-41ca-4854-aaef-c8c710490718(a)u34g2000yqu.googlegroups.com... > On 7 Apr, 23:18, PD <thedraperfam...(a)gmail.com> wrote: >> On Apr 7, 5:09 pm, Ste <ste_ro...(a)hotmail.com> wrote: [snip for brevity] >> > But certainly, there is no need to make reference to a "frame" in >> > order to calculate a "relative speed" between two objects. >> >> Yes, there is. > > Is there? (And I'm assuming we're disregarding SR). If you disregard SR, and assume only a galilean/newtonian model, then we can show mathemtically that closing velocity is not frame dependent. However, when we talk about SR (and the reality that it models far better than does the Galilean/Newtonian model), then we can no longer assume that to be the case. >> And it turns out that the relative speed between two >> objects as *measured* in different reference frames, is frame- >> dependent. Observationally. Whether you think this is nonsense or not. > > And of course, I do think that. And whether or not you do doesn't matter. What matters is what is found to happen in reality, and what the SR model predicts. They are both in agreement with what you regard as 'nonsense'.
From: Ste on 7 Apr 2010 23:17 On 8 Apr, 00:50, "Inertial" <relativ...(a)rest.com> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > I > > can even tell you what would happen, working within the same tenets, > > if with careful timing you sent in *two* ladders in *opposite* > > directions, and shut the doors simultaneously (according to the barn > > frame) so as to contain both ladders for an instant with an > > interference fit. > > 'interference fit' ? It's an engineering term. You know, where concrete reality counts. > > What I'm questioning is whether this "paradox" actually reflects > > reality at all. > > Why shouldn't it? Because of the prima facie contradiction with reality, and the deficiency (and indeed absurdity) of the explanation offered. > > It is easy to conceive of mathematical models that are > > internally consistent, ostensibly fit the existing evidence, but have > > no basis in reality > > If they predict what reality does, they are valid models A model can be valid and useful because it quantifies what you observe. But it can be invalid insofar as it offers an explanation for what is being observed. > > - mainstream economics abounds with such models > > (and is widely regarded as being empirically discredited, and the > > maths regarded as obfuscatory). > > > That leads on to my real question here. I'm not interested in being > > told *what* SR predicts - > > Clearly you aren't. Which is your first mistake. > > > which is what you've done here again for the > > umpteenth time. I'm interesting in an explanation of *why* these > > predictions would be what they are. > > Because that is how the geometry of the universe works Why not just say "Because. [full stop]"? It would have the same explanatory value. > > To > > explain *how* audio Doppler works, and to rule out the assertion that > > the source frequency "really" changes, involves an awareness of each > > step in which mechanical energy is transmitted through air to the > > receiver. > > > That's what this discussion is about. Repeating the paradox does not > > help further *explain* the paradox, or answer any of my questions in > > regard of it. When I say "why does the other object always contract", > > I don't expect to be told "because SR says it does" - that is no > > explanation at all. > > But you do not yet understand what SR says .. in particular about > simultaneity. I understand what it says about simultaneity. The problem is that I think its definition of simultaneity is absurd. > You also use ambiguous and loaded terms like 'real' and > 'subjective' in a deliberately confusing manner. No, I think it was accidentally confusing at first, but I've done everything humanly possible since to clamp down on the meaning of those words.
From: Ste on 7 Apr 2010 23:21
On 8 Apr, 02:39, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 7, 8:21 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 7 Apr, 22:45, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Apr 7, 4:24 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > But you still don't get it. "Fitting" is not a relationship between > > > > obsever and ladder. It is a relationship between ladder and barn. Why > > > > on Earth would the observer's presence and circumstances affect the > > > > fitting of these two objects, that are totally independent of the > > > > observer? > > > > To help you understand this, I'd like for you to give me a very > > > precise definition of what you mean when you say that one object A > > > will "fit" inside object B, when A and B are relatively moving. > > > Depending on the quality of your definition, I may probe it with some > > > additional questions and scenarios to see if it works. > > > It's relatively straightforward. "Fitting" is when the ladder is of > > such length that it would be possible to close both doors on the barn, > > and for the ladder to be contained completely inside. > > Remember the ladder is moving relative to the barn. > How does one determine that the ladder is contained completely inside, > exactly? By shutting the doors at the same time, of course. > For example, I could shut one door and open it, while the front of the > ladder is inside the barn, and then I could walk around to the back of > the barn and shut the other door, while the back of the ladder is > inside the barn. But by that time, the front of the ladder may have > struck the first door. Is it still true that the ladder fits inside > the barn? Indeed you could do this, but this would not prove that the ladder "fitted". |