Known physics defeated by simple puzzle?
in [Relativity]
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From: Sue... on 6 Apr 2010 14:34 On Apr 6, 12:02 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 6, 10:39 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 6 Apr, 16:28, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Apr 5, 6:41 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 5 Apr, 22:10, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > On Apr 5, 3:47 pm, Ste <ste_ro...(a)hotmail.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". > > > > > > It contracts to fit the barn in the rest frame of the barn, which is > > > > > why the ladder makes no marks on the barn doors when the doors are > > > > > shut at the same time. In the rest frame of the ladder, the ladder > > > > > does not contract and indeed does not fit inside the barn at all. In > > > > > the rest frame of the ladder, the reason why there are no marks on the > > > > > barn doors when they are shut is that they were not shut at the same > > > > > time in this frame. > > > > > This logic is easily defeated Paul, because if we contracted the > > > > ladder's length *just* enough so that it marked the door in the barn > > > > frame (in other words, the ladder has contracted just enough to manage > > > > an interference fit with both doors shut), then this cannot be > > > > accounted for in the ladder frame (because, in the ladder frame, if > > > > the ladder is *even larger* relative to the barn than when it started, > > > > then the ladder could not possibly mark the doors in the same way). > > > > I'm not sure what the fuss is. The observation is that the doors are > > > shut and open without striking the pole, and this is true in both > > > reference frames examined (as well as any other inertial reference > > > frame). The account in the ladder frame is, however, not because the > > > ladder fits inside the barn. It is exactly as I described above. Why > > > is this difficult? > > > It isn't difficult for me. I can explain it, in its entirety, in terms > > of a "visual effect" and the careful timing of the doors. It's other > > people here who keep insisting that it is not a visual effect, and > > hence the fuss. > > I don't believe it's a "visual effect" at all. The doors are closed > and opened by a common trigger, electronically. If the measuring device (barn) fortuitously changes shape to resolve the apparent light speed conflict with the principle of relativity, then you are a Lorentz ether theorist. http://en.wikipedia.org/wiki/Lorentz_ether_theory#Length_contraction Why not hang out your shingle and be done with it? It might earn you a few extra candles on you next birthday cake and a few books written since 1905 under your Christmas tree. Sue... > > Is it your claim that the doors are "really" closed and opened > simultaneously, but they only visually appear to close and open > nonsimultaneously in the ladder frame? Then how does the 80 foot > ladder fit into the 40 ft barn without the doors striking the ladder, > if the doors are "really" closed simultaneously? > > PD
From: PD on 6 Apr 2010 14:44 On Apr 5, 10:03 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > 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. > This business about a thing fitting and not fitting being a contradiction... A penny on the armrest of a plane is at rest in one reference frame and not at rest in another reference frame. Is it not obvious to you that there is a logical contradiction in those claims? How does the penny change from being at rest in one frame to not being at rest in another frame, without there being some physical interaction with the penny to cause that change? And what is it then that is interacting with the penny? And if I switch from the second frame to the first frame, can I see that physical interaction with the penny in reverse? Penny dropping from the armrest of the plane falls down in a straight line to the floor of the plane in one reference frame, but in another reference frame its path is a parabolic arc. Is it not obvious to you that there is a logical contradiction in those claims? How does the path change from being in a straight line to a parabolic arc? Doesn't the introduction of curvature to a straight line path involve the application of a force? If so, what is the new force that has been introduced? And if I switch from the second frame to the first, what have I done to make that force disappear? You see how easy it is to fool yourself with statements you believe are contradictory... PD
From: Androcles on 6 Apr 2010 15:25 <paparios(a)gmail.com> wrote in message news:0e88e02a-c0b0-4185-a187-7a021d642299(a)v20g2000yqv.googlegroups.com... On 6 abr, 12:28, Ste <ste_ro...(a)hotmail.com> wrote: > On 6 Apr, 05:54, "Inertial" <relativ...(a)rest.com> wrote: > > > > A thing cannot fit and at > > > the same time not fit, > > > yes it can.. just as it can be travelling at 100km/hr and 50 km/hr at > > the > > same time. > > But that's not true. 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*. > > And by the same token, if we are talking about the relationship > between the barn and the ladder, it cannot fit and not fit. > Again you are misunderstanding the purpose of using these inertial frames of reference on SRT. SRT says that: First postulate � The laws by which the states of physical systems undergo change are not affected, whether these changes of state be referred to the one or the other of two systems in uniform translatory motion relative to each other. ===================================================== "Take, for example, the reciprocal electrodynamic action of a magnet and a conductor. The observable phenomenon here depends only on the *** relative motion *** of the conductor and the magnet" "Examples of this sort, yada... yada... yada...". First postulate = relative motion, you disgusting LIAR!
From: Sue... on 6 Apr 2010 15:36 On Apr 6, 2:44 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 5, 10:03 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > 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. > > This business about a thing fitting and not fitting being a > contradiction... > > A penny on the armrest of a plane is at rest in one reference frame > and not at rest in another reference frame. Is it not obvious to you > that there is a logical contradiction in those claims? How does the > penny change from being at rest in one frame to not being at rest in > another frame, without there being some physical interaction with the > penny to cause that change? And what is it then that is interacting > with the penny? And if I switch from the second frame to the first > frame, can I see that physical interaction with the penny in reverse? > > Penny dropping from the armrest of the plane falls down in a straight > line to the floor of the plane in one reference frame, but in another > reference frame its path is a parabolic arc. Is it not obvious to you > that there is a logical contradiction in those claims? How does the > path change from being in a straight line to a parabolic arc? Doesn't > the introduction of curvature to a straight line path involve the > application of a force? If so, what is the new force that has been > introduced? And if I switch from the second frame to the first, what > have I done to make that force disappear? > > You see how easy it is to fool yourself with statements you believe > are contradictory... Good move PD. Change the subject from material objects to an imaginary frame of reference. Your reader surely doesn't know a picture frame from an inertial frame. <eyes rolling> <<Pseudoscience depends on arbitrary conventions of human culture, rather than on unchanging regularities of nature. For instance, the interpretations of astrology depend on the names of things, which are accidental and vary from culture to culture. If the ancients had given the name Mars to the planet we call Jupiter, and vice versa, astronomy could care less but astrology would be totally different, because it depends solely on the name and has nothing to do with the physical properties of the planet itself.>> http://www.quackwatch.org/01QuackeryRelatedTopics/pseudo.html > > PD
From: Edward Green on 6 Apr 2010 18:13
On Apr 5, 4:47 pm, Ste <ste_ro...(a)hotmail.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. It's definitely not "optical" or "visual". Relativistic length contraction and time dilation is an effect left over when all corrections for the finite speed of light have been removed. Part of resolving the paradox involves the finite speed of light also, but in a different way. Say the ladder fits from the viewpoint... ahem... "frame of reference" of the barn. What is going on in the frame of the ladder? Well, this short little barn is approaching at nearly the speed of light. The barn is too short to contain the ladder. However, the barn is going so fast that light speed impulses traveling down the ladder from the impact with the first closed barn door cannot reach the other end of the ladder before it passes through the second, open, barn door, which then closes. Viola, the ladder is in the barn. Now, if you wish to repeat the experiment with the barn doors left open, so that the ladder is not destroyed, we must have recourse to the differing time scales in the two frames, and how they interact with distance. The observer on the barn concludes that there is a moment when the ladder is completely contained in the barn, whereas the observer on the ladder, with his differing time scale, concludes there was no such moment. Ditto for a mixed version of the experiment, where we close the barn doors with a flourish, and reopen them before the ladder collides with them: the observer on the barn thinks both doors were closed simultaneously at least for a moment, whereas the observer on the ladder sees no such thing -- he sees the leading door of the shortened barn opened before he hits it, and the trailing door close after all his ladder has passed through it. Hope this helps. |