Is Length Contraction in SR physical??
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From: funkenstein on 15 Feb 2010 09:28 On Feb 5, 11:06 pm, Tom Roberts <tjrob...(a)sbcglobal.net> wrote: > Juan R. González-Álvarez wrote: > > Tom Roberts wrote on Thu, 04 Feb 2010 22:54:29 -0600: > >> No. How could arbitrary human choices of coordinates possibly affect the > >> physical phenomena that underlie the things one measures? > > > ^^^ Here is the origin of your misunderstanding :-D > > How so? > > That is, please explain how choice of coordinates does affect physical > phenomena. Well let me start by saying this looks like entirely a semantic discussion so not really important in my view. That being said, let me try to justify my comment :) The choice of coordinates clearly affects the coordinates which come out of the observation of physical phenomena, of that we agree. Perhaps more interesting is that the choice of a coordinate system which is based on electromagnetism, i.e. defining the meter in terms of the speed of light, produces the Lorentz-invarance and indeed all of SR. Tom is right that the phenomena don't care how we are observing them (provided we aren't interfering with the phenomena by making the observation) but in terms of how the equations look and how our measurements look, we'd better be careful because the choice of coordinates is very important.
From: kenseto on 15 Feb 2010 15:20 On Feb 14, 7:46 pm, "Inertial" <relativ...(a)rest.com> wrote: > "kenseto" <kens...(a)erinet.com> wrote in message > > news:e5b854b1-989a-4a1f-8bb2-b322a5bebbee(a)f34g2000yqc.googlegroups.com...> On Feb 14, 5:57 pm, "Inertial" <relativ...(a)rest.com> wrote: > >> "kenseto" <kens...(a)erinet.com> wrote in message > > [snip for brevity] > > > > > > >> >> > and thus it is not merely the geometric projection is > >> >> > shorter. > >> >> >> Do you see now? > > >> >> I guess not. > > >> >> If a ladder can fit thru a shorter doorway due to tilting (without > >> >> getting > >> >> materially shorter) then a pole can fit in a barn (without getting > >> >> materially shorter). You can't have you cake and eat it to .. if one > >> >> example is valid, so is the other. > > >> > The problem is: You can't tilt the materially longer pole enough to > >> > make it fit into a materially 1 ft tall barn. > > >> The tilt is not in just 3 dimensions in this case .. but is still a > >> tilting. > > > WE live in 3D space. > > WE live in 4 dimensions .. 3 spatial and one time. Spatial dimensions are separated from time. > > > Also if tilting is what make the pole fit into > > the barn....why can't the pole observer tilt the pole to make it fit > > into the barn? > > Its not the observers that do the tilting. Why don't the pole observer says that the barn is tilted in the time dimension and thus it become longer and thus it is able to encase the pole completely? > > > Ken Seto > > >> > Furthermore length > >> > contraction in SR is in the direction of motion....so where is this > >> > tilting of the pole comes in? > > >> It is a tilting in time. But just as much a geometric projection as > >> tilting > >> a ladder. > > >> So .. are you going to continue to run away from simple direct questions. > >> Of course you are. In case you forgot what questions you are avoiding: > > >> 1) > > You ran away again .. so to repeat the questions you continue to ignore > (both *only* in the context of tilting a ladder to fit thru a doorway): > > 1) In the case of tilting a ladder to fit thru a doorway .. Is that tilting > something physical? If not, how can tilting it change whether of not if > physically can get from one side of the doorway to the other? It is not physical or material.....iow nothing physically happening to the ladder. It is geometrical. > > 2) Do you agree that the rotation (titling) of the ladder changes something > physical about the combination of ladder and doorway (the combined system of > two objects) Nothing is changed to the ladder. What you are doing is fitting a narrow ends of the ladder through a narrower door way. ;-) Ken Seto
From: JT on 15 Feb 2010 15:43 On 15 Feb, 21:20, "kens...(a)erinet.com" <kens...(a)erinet.com> wrote: > On Feb 14, 7:46 pm, "Inertial" <relativ...(a)rest.com> wrote: > > > > > > > "kenseto" <kens...(a)erinet.com> wrote in message > > >news:e5b854b1-989a-4a1f-8bb2-b322a5bebbee(a)f34g2000yqc.googlegroups.com....> On Feb 14, 5:57 pm, "Inertial" <relativ...(a)rest.com> wrote: > > >> "kenseto" <kens...(a)erinet.com> wrote in message > > > [snip for brevity] > > > >> >> > and thus it is not merely the geometric projection is > > >> >> > shorter. > > >> >> >> Do you see now? > > > >> >> I guess not. > > > >> >> If a ladder can fit thru a shorter doorway due to tilting (without > > >> >> getting > > >> >> materially shorter) then a pole can fit in a barn (without getting > > >> >> materially shorter). You can't have you cake and eat it to .. if one > > >> >> example is valid, so is the other. > > > >> > The problem is: You can't tilt the materially longer pole enough to > > >> > make it fit into a materially 1 ft tall barn. > > > >> The tilt is not in just 3 dimensions in this case .. but is still a > > >> tilting. > > > > WE live in 3D space. > > > WE live in 4 dimensions .. 3 spatial and one time. Bullshit then we live in the dimension of senses and scent to you can not just label anything you want a dimension a dimension is spatial extension. Timelike extension is by change. > Spatial dimensions are separated from time. Correct if they had it their way flavours of turds, bananas and cucumbers would have own dimensions. > > > > > Also if tilting is what make the pole fit into > > > the barn....why can't the pole observer tilt the pole to make it fit > > > into the barn? > > > Its not the observers that do the tilting. > > Why don't the pole observer says that the barn is tilted in the time > dimension and thus it become longer and thus it is able to encase the > pole completely? > > > > > > > > > > Ken Seto > > > >> > Furthermore length > > >> > contraction in SR is in the direction of motion....so where is this > > >> > tilting of the pole comes in? > > > >> It is a tilting in time. But just as much a geometric projection as > > >> tilting > > >> a ladder. > > > >> So .. are you going to continue to run away from simple direct questions. > > >> Of course you are. In case you forgot what questions you are avoiding: > > > >> 1) > > > You ran away again .. so to repeat the questions you continue to ignore > > (both *only* in the context of tilting a ladder to fit thru a doorway): > > > 1) In the case of tilting a ladder to fit thru a doorway .. Is that tilting > > something physical? If not, how can tilting it change whether of not if > > physically can get from one side of the doorway to the other? > > It is not physical or material.....iow nothing physically happening to > the ladder. It is geometrical. > > > > > 2) Do you agree that the rotation (titling) of the ladder changes something > > physical about the combination of ladder and doorway (the combined system of > > two objects) > > Nothing is changed to the ladder. What you are doing is fitting a > narrow ends of the ladder through a narrower door way. ;-) > > Ken Seto- Dölj citerad text - > > - Visa citerad text -- Dölj citerad text - > > - Visa citerad text -
From: Inertial on 15 Feb 2010 16:01 <kenseto(a)erinet.com> wrote in message news:d8eac96d-d0b0-4d5b-bc09-8f7f2d32ca16(a)u9g2000yqb.googlegroups.com... > On Feb 14, 7:46 pm, "Inertial" <relativ...(a)rest.com> wrote: >> "kenseto" <kens...(a)erinet.com> wrote in message >> >> news:e5b854b1-989a-4a1f-8bb2-b322a5bebbee(a)f34g2000yqc.googlegroups.com...> >> On Feb 14, 5:57 pm, "Inertial" <relativ...(a)rest.com> wrote: >> >> "kenseto" <kens...(a)erinet.com> wrote in message >> >> [snip for brevity] >> >> >> >> >> >> >> >> > and thus it is not merely the geometric projection is >> >> >> > shorter. >> >> >> >> Do you see now? >> >> >> >> I guess not. >> >> >> >> If a ladder can fit thru a shorter doorway due to tilting (without >> >> >> getting >> >> >> materially shorter) then a pole can fit in a barn (without getting >> >> >> materially shorter). You can't have you cake and eat it to .. if >> >> >> one >> >> >> example is valid, so is the other. >> >> >> > The problem is: You can't tilt the materially longer pole enough to >> >> > make it fit into a materially 1 ft tall barn. >> >> >> The tilt is not in just 3 dimensions in this case .. but is still a >> >> tilting. >> >> > WE live in 3D space. >> >> WE live in 4 dimensions .. 3 spatial and one time. > > Spatial dimensions are separated from time. Reality behaves as if they are not. >> > Also if tilting is what make the pole fit into >> > the barn....why can't the pole observer tilt the pole to make it fit >> > into the barn? >> >> Its not the observers that do the tilting. > > Why don't the pole observer says that the barn is tilted in the time > dimension and thus it become longer and thus it is able to encase the > pole completely? Because the pole observers become tilted. The pole observer does not tilt the pole .. he is tilted with it. The tilting occurs due to the relative motion. Gees .. you just have no idea, do you >> >> > Furthermore length >> >> > contraction in SR is in the direction of motion....so where is this >> >> > tilting of the pole comes in? >> >> >> It is a tilting in time. But just as much a geometric projection as >> >> tilting >> >> a ladder. >> >> >> So .. are you going to continue to run away from simple direct >> >> questions. >> >> Of course you are. In case you forgot what questions you are >> >> avoiding: >> >> >> 1) >> >> You ran away again .. so to repeat the questions you continue to ignore >> (both *only* in the context of tilting a ladder to fit thru a doorway): >> >> 1) In the case of tilting a ladder to fit thru a doorway .. Is that >> tilting >> something physical? If not, how can tilting it change whether of not if >> physically can get from one side of the doorway to the other? > > It is not physical or material.....iow nothing physically happening to > the ladder. It is geometrical. Again, you refuse to answer the actual question. Is *tilting* physical. I did not ask if there was a physical change in the ladder itself .. I asked if tilting is physical. Does it change physical reality. >> 2) Do you agree that the rotation (titling) of the ladder changes >> something >> physical about the combination of ladder and doorway (the combined system >> of >> two objects) > > Nothing is changed to the ladder. What you are doing is fitting a > narrow ends of the ladder through a narrower door way. ;-) Again, you refuse to answer the actual question. Is there a physical change to the combined system of ladder + doorway? So once again 1) is tilting physical (NOT is there an intrinsic internal material change to a tilted object)? 2) does tilting a ladder make a physical change to the combined system of ladder and doorway? Maybe you'll have the decency to answer the questions asked this time.
From: JT on 18 Feb 2010 08:56
On 14 Feb, 12:09, JT <jonas.thornv...(a)hotmail.com> wrote: > On 13 Feb, 19:19, PD <thedraperfam...(a)gmail.com> wrote: > > > On Feb 13, 9:54 am, kenseto <kens...(a)erinet.com> wrote: > > > > On Feb 12, 11:32 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 11, 5:37 pm, kenseto <kens...(a)erinet.com> wrote: > > > > > > On Feb 11, 10:32 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > On Feb 11, 9:07 am, kenseto <kens...(a)erinet.com> wrote: > > > > > > > > On Feb 10, 8:49 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > On Feb 10, 4:57 pm, kenseto <kens...(a)erinet.com> wrote: > > > > > > > > > > On Feb 10, 9:39 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > > > On Feb 10, 8:06 am, kenseto <kens...(a)erinet.com> wrote: > > > > > > > > > > > > On Feb 9, 5:56 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > > > > > On Feb 9, 4:29 pm, kenseto <kens...(a)erinet.com> wrote: > > > > > > > > > > > > > > On Feb 9, 11:32 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > > > > > > > On Feb 8, 2:58 pm, kenseto <kens...(a)erinet.com> wrote: > > > > > > > > > > > > > > > > On Feb 8, 3:25 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > > > > > > > > > On Feb 7, 8:39 am, kenseto <kens...(a)erinet.com> wrote: > > > > > > > > > > > > > > > > > > > When Ken started asking these questions 15 years ago, they were > > > > > > > > > > > > > > > > > > reasonable questions. When after a couple of years it was clear he was > > > > > > > > > > > > > > > > > > not listening to the answers given to his questions, the tone of the > > > > > > > > > > > > > > > > > > responses became a little different. > > > > > > > > > > > > > > > > > > Why should I listen to what you said when you did made sense.?? > > > > > > > > > > > > > > > > > Ken, it isn't wise to stop listening to people if you do not > > > > > > > > > > > > > > > > understand what they are saying. It would be important in that case to > > > > > > > > > > > > > > > > say, "I don't understand what you are saying. Can you explain it > > > > > > > > > > > > > > > > differently so I can understand it?" > > > > > > > > > > > > > > > > I don't listen to you because you keep on making contradictory claims. > > > > > > > > > > > > > > > For example the pole is physically contracted to fit the barn and at > > > > > > > > > > > > > > > the same time the pole does not fit into the barn because it is not > > > > > > > > > > > > > > > physically contracted. > > > > > > > > > > > > > > > Those are not contradictory claims. > > > > > > > > > > > > > > Yes they are. > > > > > > > > > > > > > > >Those are different accounts made > > > > > > > > > > > > > > in different reference frames. There is no requirement that the > > > > > > > > > > > > > > accounts be identical in different reference frames, and therefore > > > > > > > > > > > > > > they are not contradictory. > > > > > > > > > > > > > > They have to agree whether the physicallengthof the pole can fit > > > > > > > > > > > > > into the shorter barn. > > > > > > > > > > > > > No, they do not. There is no such requirement. > > > > > > > > > > > > There is the requirement that if you claim physicalcontractionthen > > > > > > > > > > > the pole is really contracted > > > > > > > > > > > I have no idea what you mean by "really contracted". It is physically > > > > > > > > > > contracted in one frame because it actually fits between the doors > > > > > > > > > > when the doors are closed. How can that be called anything other than > > > > > > > > > > physical? It does NOT mean *materially* contracted though -- as in > > > > > > > > > > squeezing or cooling. > > > > > > > > > >Contractionby cooling is "really physically contracted", or > > > > > > > > > "materially contracted", and it is NOT a geometrically contracted > > > > > > > > > effect. > > > > > > > > > Indeed, but you act as though this is the ONLY way something can be > > > > > > > > physically contracted. Not so at all. > > > > > > > > > > IOW, when a meter stick is "really physically contracted" or > > > > > > > > > "materially contracted" its physicallengthor materiallengthis > > > > > > > > > "physically" or "materially" shorter than the observer's meter stick. > > > > > > > > > "Physically" does not mean "materially". Never has, Ken. Get that out > > > > > > > > of your head. It's wrong. > > > > > > > > > > I don't understand why you insist on hijacking the word "physical" and > > > > > > > > > give it a different meaning than the standard meaning. > > > > > > > > > The standard meaning is the meaning given by physicists, since that > > > > > > > > which is physical is what is studied by physics. > > > > > > > > Electric field is physical, but it is not material. This should be > > > > > > > > enough to tell you that what you think is the "standard meaning" has > > > > > > > > something wrong with it, Ken. > > > > > > > > > So much of your difficulty in understanding physics, Ken, is that you > > > > > > > > insist that words mean what you want them to mean and you never ask > > > > > > > > what they really do mean. If you only asked what some words meant in > > > > > > > > physics, so much of your misunderstandings would be quickly resolved. > > > > > > > > > > I don't > > > > > > > > > understand why you don't except the correct phrase thatlength > > > > > > > > > conraction in SR is a "geometric projection effect". > > > > > > > > > > BTW the physicallengthor materiallengthof the pole DOES NOT > > > > > > > > > actually fits between the doors when the doors are closed.. The > > > > > > > > > *geometric projection* of the pole can fit into the barn with both > > > > > > > > > doors are closed.....the reason is that geometric projection is not > > > > > > > > > physical or material. > > > > > > > > > Oh, Ken, Ken, Ken. The doors are both closed at the same time, and the > > > > > > > > ends of the pole do not touch the doors. The pole is completely inside > > > > > > > > the barn. > > > > > > > > Yet you want to insist that the pole is only geometrically inside the > > > > > > > > barn and not physically inside the barn? Is it physically sticking out > > > > > > > > of the barn? How does it physically do that without physically making > > > > > > > > marks on the barn doors where the pole physically hits them? > > > > > > > > Here's the problem: What you wrote here means that there is material > > > > > > > or physicalcontraction. Why? Because the only way that the material > > > > > > > pole can be completely inside the barn with both doors closed > > > > > > > simultaneously is that it is physically or materially contracted. > > > > > > > That is not so, Ken. You see, that is the only way YOU can think of > > > > > > this happening, and so you assume it IS the only way it can happen. In > > > > > > this way, you prevent yourself from learning anything new. > > > > > > > Things can be physically contracted without being materially > > > > > > contracted. > > > > > > However, YOU can only think of one way something can be physically > > > > > > contracted, and that's if it's materially contracted. That's YOUR > > > > > > limitation, and yours only. > > > > > > No things cannot be physically contracted without materially > > > > > contracted. > > > > > I'm sorry, Ken, but that is simply wrong. It's YOUR limitation, and > > > > yours only. > > > > Why do you insist that there is physical or materialcontraction > > > It is a physicalcontraction, not a materialcontraction. > > "Physical" does not mean "material", even in the dictionary. I pointed > > that out to you. > > > > when > > > you know damn well that it is merely a geometric projection effect? > > > It's a physical effect. > > > > > > The word physical has the meaning of "of matter; material" > > > > > in the dictionary. > > > > > That certainly isn't the meaning of "physical" as understood by > > > > physicists for *hundreds* of years. > > > > However the most knowledgeable physicists, such as Tom Roberts, > > > discard the obsolete idea of physical or materiallengthcontraction > > > in favor of geometric projectioncontraction. > > > First of all, people who visit this newsgroup are not representative > > of the physics community. If you think that as the newsgroup says, so > > says the physics community, I'm afraid you're deluded. > > Secondly, you're not in a position to judge who is the most > > knowledgeable. All that is true is that you've decided who you want to > > trust on the newsgroup, a personal choice that you've made from a > > hunch. > > Third, if you'll READ what Tom has told you, he has said that it IS a > > physical effect AND a geometric effect. Only YOU have decided that > > both can't be true and decided to ignore one of the things he told > > you. > > Dear PD please learn the difference between contracted physical matter > and contracted units. > > 1. You see if only the unit contract within the frame *physical matter > seems elongated*, but unfortunatly for SRIANS units do not contract. > 2. If only the physical matter is contracted the *material seem > contracted* within frame.' > 3. If both the unit and the matter is contracted you would not notice > within frame, but unfortunatly for SRIANS units do not contract. > 4. If both the unit and the physical matter is contracted within frame > and you decide to compare the physical matter of frame with another > restframe with physical restframe, you are juggling cucumbers and > bananas because you love intermingling ECDT. > > From this we can learn that UNITS can not be contracted only physical > matter. When you finally learn that contracted UNITS in a frame > elongates relative matter in another frame feel free to come back and > vent your missunderstandings about physics. > > Only contracted UNITS can make difference frame B,C,D,E,F to give > different measures of frame A. You see matter is not really contracted > within SPECIAL RELATIVITY within the frame. No some idiot decided to > let the units be interchangable, starting juggling cucumbers and > bananas as they belonged to same set of measurements. > > And that is wrong very wrong even so wrong that even the most smart > people on the planet have a hard time to understand what is going on > between the difference frames in SR. > > But once you acknowledge that SR gives framedependent measures oflengthand distances you can start, to bone the hoax and dismantle to > core of confusion. And it turns our that what is going on within > theory is nothing else then plain old Newtonian relativity and that > lights moves with c from emitter and c+v and c-v relative the > observer. > > So disrobe the theory from framevariant meters, and the truth will be > clear for anyone who want to understand SR. > > JT> > > If you'd like something more accurate, you can look here:http://en.wikipedia.org/wiki/Physical_property > > > > > Even in the dictionary, the definition that is relevant to physics is > > > > listed as follows: > > > > "3. Of or relating to matter and energy or the sciences dealing with > > > > them, especially physics." > > > > Note that energy is NOT matter, and so physical is not limited to > > > > matter, even in the dictionary. > > > > You can find that here:http://www.thefreedictionary.com/physical > > > You see, Ken? Physical does NOT mean material. > > > > > > I don't understand why you insist to give the word > > > > > physical a new meaning that is not associated with material. > > > > > It is not a new meaning. The meaning that includes more than material > > > > has been in use for *hundreds* of years. > > > Get this through your gears. > > > > > > Furthermore in SR there is geometriccontractioneffect....why don't > > > > > you use that instead of "physicalcontraction"? > > > > > Ken, it is not the obligation of science to describe things using > > > > terms about which you could not possibly be confused. Part of the work > > > > in studying physics is learning the jargon -- that means learning the > > > > specialized meanings of the words as they are used in physics. You > > > > will note that in your freshman physics book, there is a lot of > > > > attention spent on defining words very carefully because they mean > > > > things other than the dictionary definitions. > > > > > I get that you think this is unfair. It's not. You just have to work > > > > with it. > > > > > > > > If > > > > > > > this is true then why do you need the explanation thatlength > > > > > > >contractionin SR is a geomrtical projection effect? > > > > > > > > > Do you see what kind of nonsense your word games get you into? > > > > > > > > ROTFLOL....it is you who is > > > ... > > > läs mer » I just feel you let the unit hangin again...... JT |