Is Length Contraction in SR physical??
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From: kenseto on 1 Feb 2010 09:55 Is Length Contraction in SR physical?? According the most informed SRian, Tom Roberts, the answer to this question is NO. His answer is that length contraction is the geometric projection effect of the length of a moving meter stick onto the SR observer's frame. When a moving meter stick rejoins the stay at home meter stick they will have the same physical length. Furthermore if length contraction is physically real how come SR does not predict length expansion? Is that becasue SR assumes that the observer is in a state of absolute rest? So what does it mean when SR says that a moving meter stick is contracted? The answer: 1. An SR observer assumes that the light path length of his meter stick is the same as the physical length of his meter stick. 2. Using this standard the light path length of a meter stick moving wrt an SR observer is shorter than the light path length of the stay at home meter stick. Why? Because light generated at the front end of the stick will reach the rear end of the stick sooner for a moving meter stick (c+v) according to the stay at home SR observer. 3. So according to the SR observer the light path length of a moving meter stick is as follows: L' = L_o/gamma. 4. The above interpretation avoids all the paradoxes that arise due to the bogus interpretation that a moving meter stick is physically contracted. However, the above interpretation is incomplete. Why? Because the light path length of a meter stick moving wrt the observer may be longer than the observer's meter stick. In that case the light path length of such meter stick is calculated as follows: L' = L_o(gamma) This interpretation is included in a new theory of relativity called Improved Relativity Theory (IRT). IRT includes SRT as subset. However, the equations of IRT are valid in all environments, including gravity. A complete description of IRT is available in the following link: http://www.modelmechanics.org/2008irt.dtg.pdf Ken Seto Reply to author Forward You must Sign in before you can post messages. To post a message you must first join this group. Please update your nickname on the subscription settings page before posting. You do not have the permission required to post.
From: Igor on 1 Feb 2010 10:11 On Feb 1, 9:55 am, "kens...(a)erinet.com" <kens...(a)erinet.com> wrote: > Is Length Contraction in SR physical?? > According the most informed SRian, Tom Roberts, the answer to this > question is NO. His answer is that length contraction is the geometric > projection effect of the length of a moving meter stick onto the SR > observer's frame. When a moving meter stick rejoins the stay at home > meter stick they will have the same physical length. Furthermore if > length contraction is physically real how come SR does not predict > length expansion? Is that becasue SR assumes that the observer is in a > state of absolute rest? > > When people walk away from me, they appear to get smaller. Is that physical? And no matter which direction, they walk away from me, they always get smaller. How come nature doesn't allow them to appear to get bigger?
From: eric gisse on 1 Feb 2010 11:08 kenseto(a)erinet.com wrote: > Is Length Contraction in SR physical?? No, just as it has been explained to you repeatedly since the mid 90's. [...]
From: Dirk Van de moortel on 1 Feb 2010 11:09 Igor <thoovler(a)excite.com> wrote in message 36f39b8d-b930-487a-9a3d-fbfae25c24ea(a)g1g2000yqi.googlegroups.com > On Feb 1, 9:55 am, "kens...(a)erinet.com" <kens...(a)erinet.com> wrote: >> Is Length Contraction in SR physical?? >> According the most informed SRian, Tom Roberts, the answer to this >> question is NO. His answer is that length contraction is the geometric >> projection effect of the length of a moving meter stick onto the SR >> observer's frame. When a moving meter stick rejoins the stay at home >> meter stick they will have the same physical length. Furthermore if >> length contraction is physically real how come SR does not predict >> length expansion? Is that becasue SR assumes that the observer is in a >> state of absolute rest? >> >> > > When people walk away from me, they appear to get smaller. Is that > physical? And no matter which direction, they walk away from me, they > always get smaller. How come nature doesn't allow them to appear to > get bigger? When Chuck Norris walks away from you, he appears to get bigger. Dirk Vdm
From: PD on 1 Feb 2010 12:25
On Feb 1, 8:55 am, "kens...(a)erinet.com" <kens...(a)erinet.com> wrote: > Is Length Contraction in SR physical?? > According the most informed SRian, Tom Roberts, the answer to this > question is NO. Two comments: 1. You are taking a survey among those people that choose to respond to you on sci.physics, a hobbyist newsgroup. Tom is one of a few physicists that frequents the newsgroup. This may make him one of the better informed people about SR *on this newsgroup*, but it by no means indicates that he is "the most informed SRian", any more than if you took a survey of who was the tallest person on your block in Xenia, that this person would be the tallest person in Ohio. 2. Secondly, he did NOT say that the length contraction is not physical. What he did say is that the word "physical" has an ambiguous meaning at best and does not mean what you think it means. What he did say is that physics deals with what is MEASURED, and what is measured is therefore physical in that sense. It was you and ONLY you that said that if it is a geometric effect (which it is), then it CANNOT be called a physical effect. Tom did not make that statement. You did. > His answer is that length contraction is the geometric > projection effect of the length of a moving meter stick onto the SR > observer's frame. When a moving meter stick rejoins the stay at home > meter stick they will have the same physical length. Furthermore if > length contraction is physically real how come SR does not predict > length expansion? Is that becasue SR assumes that the observer is in a > state of absolute rest? > > So what does it mean when SR says that a moving meter stick is > contracted? > The answer: > 1. An SR observer assumes that the light path length of his meter > stick is the same as the physical length of his meter stick. > 2. Using this standard the light path length of a meter stick moving > wrt an SR observer is shorter than the light path length of the stay > at home meter stick. Why? Because light generated at the front end of > the stick will reach the rear end of the stick sooner for a moving > meter stick (c+v) according to the stay at home SR observer. > 3. So according to the SR observer the light path length of a moving > meter stick is as follows: > L' = L_o/gamma. > 4. The above interpretation avoids all the paradoxes that arise due > to > the bogus interpretation that a moving meter stick is physically > contracted. > > However, the above interpretation is incomplete. Why? Because the > light path length of a meter stick moving wrt the observer may be > longer than the observer's meter stick. In that case the light path > length of such meter stick is calculated as follows: > L' = L_o(gamma) > This interpretation is included in a new theory of relativity called > Improved Relativity Theory (IRT). IRT includes SRT as subset. > However, > the equations of IRT are valid in all environments, including > gravity. > A complete description of IRT is available in the following link:http://www.modelmechanics.org/2008irt.dtg.pdf > > Ken Seto > > Reply to author Forward > > You must Sign in before you can post messages. > To post a message you must first join this group. > Please update your nickname on the subscription settings page before > posting. > You do not have the permission required to post. |