Known physics defeated by simple puzzle?
in [Relativity]
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From: Inertial on 5 Apr 2010 22:06 "Sue..." <suzysewnshow(a)yahoo.com.au> wrote in message news:43593489-ed06-42f6-b4e8-2005ee4cf120(a)k19g2000yqn.googlegroups.com... > On Apr 5, 9:25 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > =============== > >> >> Indeed, except that the lack of simultaneity here is a *visual* >> effect. And that's always where the monacles fall into the drinking >> glasses. > > Hint 1 > Einstein wrote of an *apparent* conflict with PoR and "c". > > Hint 2 > http://farside.ph.utexas.edu/teaching/em/lectures/node108.html Almost relevant.
From: Sue... on 5 Apr 2010 22:11 On Apr 5, 10:06 pm, "Inertial" <relativ...(a)rest.com> wrote: > "Sue..." <suzysewns...(a)yahoo.com.au> wrote in message > > news:43593489-ed06-42f6-b4e8-2005ee4cf120(a)k19g2000yqn.googlegroups.com... > > > On Apr 5, 9:25 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > =============== > > >> Indeed, except that the lack of simultaneity here is a *visual* > >> effect. And that's always where the monacles fall into the drinking > >> glasses. > > > Hint 1 > > Einstein wrote of an *apparent* conflict with PoR and "c". > > > Hint 2 > >http://farside.ph.utexas.edu/teaching/em/lectures/node108.html > > Almost relevant. Neanderthal http://farside.ph.utexas.edu/teaching/em/lectures/node50.html <replonk>
From: Inertial on 5 Apr 2010 22:24 "Sue..." <suzysewnshow(a)yahoo.com.au> wrote in message news:34561c17-8d4f-46eb-b3ab-da067cce63d4(a)q15g2000yqj.googlegroups.com... > On Apr 5, 10:06 pm, "Inertial" <relativ...(a)rest.com> wrote: >> "Sue..." <suzysewns...(a)yahoo.com.au> wrote in message >> >> news:43593489-ed06-42f6-b4e8-2005ee4cf120(a)k19g2000yqn.googlegroups.com... >> >> > On Apr 5, 9:25 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> > =============== >> >> >> Indeed, except that the lack of simultaneity here is a *visual* >> >> effect. And that's always where the monacles fall into the drinking >> >> glasses. >> >> > Hint 1 >> > Einstein wrote of an *apparent* conflict with PoR and "c". >> >> > Hint 2 >> >http://farside.ph.utexas.edu/teaching/em/lectures/node108.html >> >> Almost relevant. > > Neanderthal That's you > http://farside.ph.utexas.edu/teaching/em/lectures/node50.html Even less relevant .. unless you are pointing out that you have retarded potential > <replonk> You don't like when your irrelevance is pointed out, do you? Yet you keep doing it. You are a strange person.
From: Ste on 5 Apr 2010 23:03 On 6 Apr, 01:13, "Inertial" <relativ...(a)rest.com> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:a7d6645c-1261-4fc7-8528-69ff1cb56e33(a)v20g2000yqv.googlegroups.com... > > > On 5 Apr, 01:38, "Inertial" <relativ...(a)rest.com> wrote: > >> "Ste" <ste_ro...(a)hotmail.com> wrote in message > > >> > Incidentally, this book (which was a link from Wikipedia) confirms my > >> > statement that GR is how the paradox was apparently resolved (at least > >> > by Einstein and a few others): > >> >http://books.google.com/books?id=vuTXBPvswOwC&pg=PA165#v=onepage&q=&f... > > >> You CAN use GR .. which is a superset of SR. But SR 'solves' it as well > > > As I say, that's not how I understand it, > > That is your problem. You need to learn. Not flaunt your ignorance. Lol. I'm all for "flaunting". > > and the written evidence > > elsewhere (for example, in the link I've just provided) suggests that > > even Einstein clearly felt that GR was necessary to explain it. > > But it is NOT necessary. Einstein even gave it as an example in his 1905 > paper (though not with actual twins .. with moving clocks) > > > At the > > very least, you can see that I'm subject to contradictory evidence > > here, > > No contrary evidence. > > > and you can understand why I don't take your statement here at > > face value. > > Do you need links to the many SR solutions to the twins paradox? The only SR "solution" I've seen to the twins paradox is the one about "changing frames", but it's divorced from reality and therefore repugnant to me. And obviously, I don't want a purely mathematical explanation either. I want an explanation that involves words and meaningful concepts (or possibly pictures that represent real objects). > >> >> > but > >> >> > as I understand it, you need GR to account for acceleration (in > >> >> > other > >> >> > words, it's outside the scope of this discussion). > > >> >> Wrong .. you've had that told to you many times. SR handles > >> >> acceleration > >> >> just fine > > >> > As I say, the information I have suggests that GR is necessary to > >> > account for the (absolute) acceleration, > > >> That is wrong > > >> > whereas SR treats > >> > acceleration merely as a change of relative velocity > > >> It is a change in velocity > > > Yes, but do you mean a relative change of velocity or (shall we say) > > an "absolute" change of velocity? > > There is no difference There is in the sense that I mean, where a change of relative velocity can be accomplished without any acceleration (or "impulse" as I think we previously agreed to describe it). > > Remember, relative velocity can > > change without absolute acceleration. > > No Yes. I mean "impulse" btw. > > Indeed, a bullet that flies past > > your ear undergoes a dramatic change of relative velocity to you as it > > passes (it approaches and then recedes), > > No .. it doesn't I would argue that it does, if you make reference only to the bullet and the ear. How would you explain, say, the change in Doppler shifting unless there was a change of relative velocity when something passes you? Anyway, I suppose it's an aside. > > Clearly relative velocities can change with or without an > > application of force > > No I mean "without an application of force to both objects". > >> >> >> The ladder really does fit inside the barn. > > >> >> > But then it must fit inside the barn from *all* frames, > > >> >> Why? > > >> > Because "fitting" and "not fitting" are two mutually exclusive states. > > >> You haven't answered the question > > > I think I have. I've insisted that the two states are mutually > > exclusive, and I've elaborated on it below. > > You still haven't answered why 'fitting' must be absolute Because of the obviousness of the concept. A thing cannot fit and at the same time not fit, because there is a logical contradiction in the meaning of those words. And nor can the state be subjective for each observer, otherwise that isn't materialism (and it isn't causal either). Or to repeat my earlier analogy, you can't hit a person over the head with a hammer, and merely daze him *at the same time as* cracking his skull wide open. > >> >> It doesn't have the same speed in all frames. It doesn't have the > >> >> same momentum in all frames. It doesn't have the same kinetic energy > >> >> in > >> >> all > >> >> frames. Why must it have the same length? > > >> > Because the notion of "speed", "energy" and "momentum" are all > >> > inherently relative concepts. > > >> As are length and duration > > > I don't see how length can be inherently relative (although its > > appearance certainly can be, as I illustrated in a previous post). > > Because it is a frame dependent measurement. > > It is is your problem if you don't see how frame dependent measurements are > frame dependent. I personally think it's just a visual effect - that is, a consequence of how of how the source and receiver interact electromagnetically. I can understand frame dependence - I just don't see how you can call the resulting observation "real". > > You can't say "it > > fits according to some observers", > > Yes you can. Just like you can say a train whistle has different pitches > for different observers But I don't say that, do I? I say the train whistle has an inherent pitch, which then translates in different ways into a apparent received pitch. Remember I've just been discussing this at length with Peter Webb earlier in the thread. > > because that is absurd > > Its not .. its physics. It is not physics fault if you find it absurd I don't find "physics" absurd. I find certain people absurd. > > as saying > > "he was merely dazed according to some observers". > > That is not equivalent Why isn't it? If "kinetic energy" is "relative", then why, in your reasoning, can he not suffer differing degrees of injury depending on how you observe it? Because that's basically the sort of argument you're making with this length contraction. > >> > The same is true of this ladder problem. If the ladder contracts, then > >> > it will fit in the barn, and if it doesn't contract then it won't fit > >> > - but it cannot contract at the same time as not contracting, or fit > >> > at the same time as not fitting. > > >> Wrong > > >> > However, it can *appear* to do so by careful timing of the doors and > >> > careful placement of the observer, and so naturally I'm saying to > >> > myself "this must be what you mean". > > >> No .. it really fits. You really need to understand the scenario before > >> drawing conclusions from it > > > I do understand the scenario. It is explained by the apparent timing > > of the doors. > > The timing of the doors is PART of the scenario. It states that they shut > (briefly) at the same time according to any observer (or observers) at rest > wrt the barn. The pole fits between them when they are simultaneously shut Yes, but that depends on simultaneous *according to whom*, and because (as Paul Draper has noticed) I use a different definition of "simultaneous" to "most of the physics community". > >> >> > including the > >> >> > rest frame of the ladder. And I know that is not what SR predicts.. > > >> >> But you are insisting that only things that are frame independent are > >> >> real > >> >> (which rules out a large amount of what we measure and work with in > >> >> physics). > > >> > No, I'm insisting that observations/changes can have a "real" basis, > >> > or an "apparent" basis, at least for the purposes of this argument . > > >> So velocity, momentum etc do not have a real basis, according to your > >> logic > > > I didn't say that. > > You said that for anything to be real, it must be the same for all > observerse .. so yes .. you did It depends what we mean. All observers agree on, for example, the velocity between any two objects. > >> > And indeed, a lot of the things you may be working with and measuring > >> > in physics are "apparent" and not "real". And I will state the > >> > definition of "apparent": "appearing as such but not necessarily so".. > > >> So velocity, momentum etc do not have a real basis, according to your > >> logic > > > I didn't say that. > > You said that for anything to be real, it must be the same for all > observerse .. so yes .. you did Yes, but the opposite of "real" here is not "imaginary", it is "apparent". I want to avoid discussing unrelated topics, especially when I can tell intuitively that when you use phrases like "do not have a real basis", you have failed to grasp the meaning that I'm employing, and what is more, you now propose I spend time defining a word in relation to concepts that it did not need to be defined for. As I said, it seemed to me that everyone understood the meaning of the words "apparent" and "real" when I mentioned the spaceship on the television monitor. Why is it so hard to generalise from that, and accept that appearances do not always reflect reality, and what appears to be the case may not be the case? That's really all I'm getting at here, when I say that while length contraction may *appear* to occur, it is merely that, an appearance. There is no mechanical, physical, material, concrete contraction at all. And although you insist the length contraction is real, until you indicate convincingly that you even know how to discern between appearance and reality, I'm not going believe you when you simply assert that the contraction is real. > >> >> So if you stand on the the highway and a car travelling at 100km/h > >> >> runs > >> >> into > >> >> you, you don't need to worry, because it isn't really travelling fast > >> >> (velocity isn't real by your standard), and doesn't really have a > >> >> large > >> >> amount of momentum and kinetic energy (momentum and kinetic energy > >> >> isn't > >> >> real by your standard) that it imparts into you and your death isn't > >> >> real. > > >> > But I will be apparently dead. ;) > > >> So you die from apparent causes and not real ones. > > > No, I was just joking, as indicated by wink and the follow-on > > "seriously though"... > > But the point remains .. these things that are not 'real', according to your > defintion, really can kill you. Looks can kill. But that's not the point. Sunlight directed through a magnifying glass can burn, even though people can sit under the sun fairly harmlessly otherwise. But the sun only *appears* scorching to those under the magnifying glass. That's not to say the resulting burns are "not real", but there is a question as to whether the sun is "inherently" scorching, or whether it is because you have manipulated the sun's rays with a lens. Or perhaps to put it another way, when you look through the magnifying glass at the sun, does it "really" become inherently small and intense (and does looking through the lens "really" cause a contraction in the sun, despite it being millions of miles away), or are you just manipulating the rays again? > >> > Seriously though, I didn't say velocity was "not real", > > >> Yes .. you did .. when you said something is only real if it is the same > >> for > >> all observers > > > Yes, indeed. And the hammer hits the skull with the same velocity, the > > same force, and with the same effect, according to all observers. I > > really don't see what is difficult about this. > > But the velocity of the hammer is different in different frames .. and so, > by your definition, is not real No, the velocity of the hammer *relative to the skull* is invariant across all frames. Hence, by my definition, it *is* real. > > Or, you can > > think of it as an interaction between two objects that all observers > > agree about (and which is not relative, like the skull-cracking > > scenario). > > No .. they do NOT all agree about it, because it is, like velocity and > momentum and energy etc, a frame-dependent interaction Then you're back to saying that according to one observer, the hammer completely shatters the skull and kills the man, whereas according to another observer, the hammer blow merely dazes the man - because, after all, "energy and momentum are frame-dependent", and if there is a different amount of energy and momentum in the hammer, a therefore different amount of force applied to the skull, then by your own reasoning, the above is a valid argument. Except, of course, we both know it's absurd. > >> > about my "speaking > >> > clock" - I had previously said that it ticked loudly, but let's make > >> > it even more easy to imagine by saying that it consists of just black > >> > box with an audio speaker, and it "speaks" the time out loud every > >> > second. Do you not accept that the faster you move away from the > >> > speaking clock, the slower the clock appears to go? > > >> That's an audio illusion (or optical if you are reading the time) due to > >> delays in signal. > > >> That is NOT what happens in SR when we say clocks are measured as running > >> slow. > > > Well, do you accept that this is at least *one* of the causes of why a > > clock will appear to run slow? > > That you can ALSO have optical (and audio) illusion does not mean that that > is the cause of the SR effect being discussed Yes, but can we nail this down first. Is this optical/audio effect relevant to SR? Does it explain at least *partly* the observations in SR? I mean, you must concede, the parallels are startling.
From: Ste on 5 Apr 2010 23:07
On 6 Apr, 03:00, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > On 5 abr, 21:25, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 6 Apr, 01:38, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > > > > On 5 abr, 19:33, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 5 Apr, 21:59, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > > > > > > On 5 abr, 16:47, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 5 Apr, 17:37, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > I'm happy to make concessions, but I have to be able to ask questions > > > > > > and get meaningful answers. The ladder in the barn is a prime example. > > > > > > I'm told "the ladder contracts to fit in the barn". And I ask "so a > > > > > > person riding the ladder would see the barn expand", and the answer > > > > > > comes back "no, no, the person riding the ladder would see the barn > > > > > > *contract*". So I say, "well clearly in the latter case the ladder > > > > > > cannot possibly fit with both doors shut, so it must be a visual > > > > > > effect". "No, no" comes the reply, "the ladder *really* does fit > > > > > > according to a person standing in the barn, and it *really* doesn't > > > > > > fit according to the person riding the ladder". And I say, "well, it > > > > > > can't do both at once", and the reply that is merely asserted in > > > > > > response is "well, it does!". > > > > > > > And that sums up thousands of words in probably hundreds of posts > > > > > > exchanged between me and a quite a few posters on the ladder and barn > > > > > > paradox. It always comes back to a plain assertion that "this is how > > > > > > it works", but there is no attempt to explain *why*, or any attempt to > > > > > > show how a mere visual explanation would not suffice for some or all > > > > > > of the observed effects. > > > > > > There are plenty of places where this so called "paradox" is > > > > > explained. For instance,http://hyperphysics.phy-astr.gsu.edu/HBASE/Relativ/polebarn.html > > > > > > The relevant part is that the fact that two events are simultaneous in > > > > > one frame of reference does not imply that they are simultaneous as > > > > > seen by an observer moving at a relativistic speed with respect to > > > > > that frame. > > > > > As far as I'm concerned Miguel, I already understand the paradox. Even > > > > the page you reference says quite clearly: > > > > > "From the pole point of view, the front gate closes just as the back > > > > of the pole enters. The surprising result is that the back gate is > > > > seen to close earlier from the pole framework, before the front of the > > > > pole reaches it. The gate closings are not simultaneous, and they > > > > permit the pole to pass through without hitting either gate." > > > > > As it says, the simple explanation is that the gates don't close at > > > > the same time according to the pole, and hence the pole sails straight > > > > through. > > > > That is totally correct. It means the paradox is not a paradox at all, > > > since events that are simultaneous on one frame of reference (the > > > barn) are not simultaneous on the other frame of reference (the one of > > > the pole). Piece of cake.... > > > Indeed, except that the lack of simultaneity here is a *visual* > > effect. And that's always where the monacles fall into the drinking > > glasses. > > It is a measured effect (provided you could accelerate a pole to those > speeds and put some instruments on it). The relevant events are the > aperture/closure of the barn doors, which are as real as they can be. > On the barn frame of reference both doors could be safely closed, > simultaneously, for 1 nanosecond, with the pole inside the barn and > not touching any of the doors (those are two events, which in the > frame of reference of the barn are simultaneous). On the pole frame of > reference, these same two events do happen (as they should since any > two physical events happening on one frame have also to be observed in > any other frame), but this time they are not simultaneous (one door > closes-opens before the other door). I still fail to see any plausible explanation for the difference in simultaneity, except that it is due to a careful placement of the observer and a differential in the delay of propagation. Incidentally, do the doors shut at different times depending on *where* you sit on the ladder? |