Is Length Contraction in SR physical??
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From: kenseto on 2 Feb 2010 12:54 On Feb 2, 10:19 am, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 2, 8:45 am, kenseto <kens...(a)erinet.com> wrote: > > > > > > > On Feb 1, 11:36 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > > > > kenseto wrote: > > > > On Feb 1, 6:42 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > > > >> This is a LINGUISTIC issue. When someone asks "Is length contraction in SR > > > >> physical?", they invariably don't have a definite meaning of "physical" in mind > > > >> (if they did, they could answer the question themselves). Generally, they would > > > >> consider a "physical length contraction" to mean that the object ITSELF gets > > > >> physically shorter. This is manifestly not so in SR. But it is indeed what > > > >> kenseto has repeatedly failed to understand. > > > > > The general public know what physical length means.....the length of a > > > > ruler is physical. > > > > You clearly haven't a clue. In SR, length is most definitely not "physical" in > > > the usual sense. In the USUAL sense, physical attributes of an object do not > > > change with the way someone looks at it. > > > Right the physical length (or material length) of a ruler does not > > change no matter who is look at it. > > You are not listening. Tom *just* got through telling you that > "physical length" and "material length" are not necessarily > synonymous, and yet you just repeated your assumption that they are. > > > > > >But the length of an object DOES change > > > with the way one looks at the object (i.e. which inertial frame one uses to > > > measure its length). > > > This length change is not physical (or material) length change....it > > is a projection effect or a rotational effect. > > It is not a material effect, but it IS a physical effect. Material and > physical do not mean the same thing. > > > > > > > Much like I see you to > > be shorter from a distance. BTW no measurement of length contraction > > ever been made so you do you keep on using the word measure? > > > >The related PHYSICAL attribute is proper length -- that is > > > an attribute of an object that is intrinsic to the object (and does not change > > > with how one looks at it -- it is an invariant). > > > Right....the proper length of a ruler is the physical or material > > length of the ruler. It is invarient. > > > > > If you don't like the word physical how about > > > > "material" length contraction? In any case you stated above that > > > > material length contraction does not occur in SR and I agree with that > > > > fully. So I don't know why you accused me of repeatly failed to > > > > understand!!!!!! > > > > Indeed, you clearly do not understand why I say you fail to understand this, > > > because you STILL don't understand it. Your statement three sentences earlier > > > ("the length of a ruler is physical") CONTRADICTS your claim here. > > > I didn't fail to understand anything. You said that in SR length > > contraction is not physical and I agreed. > > > > The word "physical" has at least two different meanings that could be applied here: > > > So why bother to invent a new meaning for the word physical that > > contradicts the dictionary meaning for the word physical??? > > Words used in physics have more precise meanings than the ones found > in the dictionary. If you want to communicate with physicists about > physics, then it is extremely important to DROP the meanings of words > as listed in the dictionary and LEARN the meanings of those same words > as they are used by physicists. > > > > > > > Why not > > just stick to the correct meeaning of length contraction in SR: that > > length contraction is a geometric projection effect??? > > > > A) the object itself contracts > > > B) the object itself does not change, but the measurements have > > > physical consequences (such as a long pole fitting in a short barn > > > when moving rapidly enough wrt the barn). > > > > (A) is not correct in SR; > > > I agree. > > > > (B) is correct in SR. Both COULD be called "physical" > > > so one MUST specify what they mean when they use that word in this context. > > > No both cannot be called physical or material.... > > They are both physical. Only (A) is material, but (B) is also > physical. "Physical" does not mean "material". The electric field of a > charged object is not material but it is very physical. > > > remember physical > > length or material length is invariant as you said in A. You invented > > a new meaning for the word physical that is contradictory to the > > dictionary meaning for for the word physical or material. B is correct > > if you said that the geometric projection of a moving rod is > > contracted. > > It is not contradictory. It's just DIFFERENT. Physics uses certain > words to have very precise and special meanings that are DIFFERENT > than the definitions you will find in the dictionary. Sure it is contradictory. 1. Physical length is invariant as per the dictionary. 2. Physical length is observer dependent as per SR . These are two contradictory definition for Physical Length. Ken Seto > > > > > > > > When you use the word "physical" without saying what you mean by it, people get > > > confused. ESPECIALLY YOURSELF. > > > There is no confusion on my part. There is only one correct meaning > > for the word "physical" and I agree with you that physical length or > > material length is invariant. > > > Ken Seto > > > > Ditto for "material"-- changing the word does not change the problem. > > > > > BTW your SR brothers PD and other disagree with you. They insisted > > > > that a moving meter stick itself gets physically (materially) > > > > shorter. > > > > Again you demonstrate your inability to read or understand. PD most definitely > > > did NOT say that. I'm not sure what "others" you mean. In any case, you _REALLY_ > > > _REALLY_ _REALLY_ need to learn how to read. You have no hope whatsoever of > > > understanding subtle concepts like SR until you learn how to read. > > > > [I give up. It's hopeless until you LEARN how to read..] > > > > Tom Roberts- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -
From: rotchm on 2 Feb 2010 13:26 > > Define 'physical' > > Look up the dictionary. Ken, words have meanings depending of contexts. Here 'physical' in the english language in *physics*, is not defined. If you dont believe me, look it up in the dictionary. That word is not there. (Look it up in the appropriate dictionary!)
From: PD on 2 Feb 2010 14:14 On Feb 2, 11:54 am, "kens...(a)erinet.com" <kens...(a)erinet.com> wrote: > On Feb 2, 10:19 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 2, 8:45 am, kenseto <kens...(a)erinet.com> wrote: > > > > On Feb 1, 11:36 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > > > > > kenseto wrote: > > > > > On Feb 1, 6:42 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > > > > >> This is a LINGUISTIC issue. When someone asks "Is length contraction in SR > > > > >> physical?", they invariably don't have a definite meaning of "physical" in mind > > > > >> (if they did, they could answer the question themselves). Generally, they would > > > > >> consider a "physical length contraction" to mean that the object ITSELF gets > > > > >> physically shorter. This is manifestly not so in SR. But it is indeed what > > > > >> kenseto has repeatedly failed to understand. > > > > > > The general public know what physical length means.....the length of a > > > > > ruler is physical. > > > > > You clearly haven't a clue. In SR, length is most definitely not "physical" in > > > > the usual sense. In the USUAL sense, physical attributes of an object do not > > > > change with the way someone looks at it. > > > > Right the physical length (or material length) of a ruler does not > > > change no matter who is look at it. > > > You are not listening. Tom *just* got through telling you that > > "physical length" and "material length" are not necessarily > > synonymous, and yet you just repeated your assumption that they are. > > > > >But the length of an object DOES change > > > > with the way one looks at the object (i.e. which inertial frame one uses to > > > > measure its length). > > > > This length change is not physical (or material) length change....it > > > is a projection effect or a rotational effect. > > > It is not a material effect, but it IS a physical effect. Material and > > physical do not mean the same thing. > > > > Much like I see you to > > > be shorter from a distance. BTW no measurement of length contraction > > > ever been made so you do you keep on using the word measure? > > > > >The related PHYSICAL attribute is proper length -- that is > > > > an attribute of an object that is intrinsic to the object (and does not change > > > > with how one looks at it -- it is an invariant). > > > > Right....the proper length of a ruler is the physical or material > > > length of the ruler. It is invarient. > > > > > > If you don't like the word physical how about > > > > > "material" length contraction? In any case you stated above that > > > > > material length contraction does not occur in SR and I agree with that > > > > > fully. So I don't know why you accused me of repeatly failed to > > > > > understand!!!!!! > > > > > Indeed, you clearly do not understand why I say you fail to understand this, > > > > because you STILL don't understand it. Your statement three sentences earlier > > > > ("the length of a ruler is physical") CONTRADICTS your claim here. > > > > I didn't fail to understand anything. You said that in SR length > > > contraction is not physical and I agreed. > > > > > The word "physical" has at least two different meanings that could be applied here: > > > > So why bother to invent a new meaning for the word physical that > > > contradicts the dictionary meaning for the word physical??? > > > Words used in physics have more precise meanings than the ones found > > in the dictionary. If you want to communicate with physicists about > > physics, then it is extremely important to DROP the meanings of words > > as listed in the dictionary and LEARN the meanings of those same words > > as they are used by physicists. > > > > Why not > > > just stick to the correct meeaning of length contraction in SR: that > > > length contraction is a geometric projection effect??? > > > > > A) the object itself contracts > > > > B) the object itself does not change, but the measurements have > > > > physical consequences (such as a long pole fitting in a short barn > > > > when moving rapidly enough wrt the barn). > > > > > (A) is not correct in SR; > > > > I agree. > > > > > (B) is correct in SR. Both COULD be called "physical" > > > > so one MUST specify what they mean when they use that word in this context. > > > > No both cannot be called physical or material.... > > > They are both physical. Only (A) is material, but (B) is also > > physical. "Physical" does not mean "material". The electric field of a > > charged object is not material but it is very physical. > > > > remember physical > > > length or material length is invariant as you said in A. You invented > > > a new meaning for the word physical that is contradictory to the > > > dictionary meaning for for the word physical or material. B is correct > > > if you said that the geometric projection of a moving rod is > > > contracted. > > > It is not contradictory. It's just DIFFERENT. Physics uses certain > > words to have very precise and special meanings that are DIFFERENT > > than the definitions you will find in the dictionary. > > Sure it is contradictory. > 1. Physical length is invariant as per the dictionary. Really? You'll have to cite a dictionary definition for "physical length" that includes the word "invariant". As usual, you are *assuming* connections that ought not to be made. I'll remind you that "physical" does NOT mean "material". > 2. Physical length is observer dependent as per SR . Yes, indeed. > These are two contradictory definition for Physical Length. SR is right. Statement (2) is right. Statement (1) is not right, and there is no reference you can point to that makes statement (1). It came out of your head. > > Ken Seto > > > > > > > When you use the word "physical" without saying what you mean by it, people get > > > > confused. ESPECIALLY YOURSELF. > > > > There is no confusion on my part. There is only one correct meaning > > > for the word "physical" and I agree with you that physical length or > > > material length is invariant. > > > > Ken Seto > > > > > Ditto for "material"-- changing the word does not change the problem. > > > > > > BTW your SR brothers PD and other disagree with you. They insisted > > > > > that a moving meter stick itself gets physically (materially) > > > > > shorter. > > > > > Again you demonstrate your inability to read or understand. PD most definitely > > > > did NOT say that. I'm not sure what "others" you mean. In any case, you _REALLY_ > > > > _REALLY_ _REALLY_ need to learn how to read. You have no hope whatsoever of > > > > understanding subtle concepts like SR until you learn how to read. > > > > > [I give up. It's hopeless until you LEARN how to read.] > > > > > Tom Roberts- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -
From: "Juan R." González-Álvarez on 2 Feb 2010 14:17 Tom Roberts wrote on Mon, 01 Feb 2010 22:36:35 -0600: > kenseto wrote: >> On Feb 1, 6:42 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: >>> This is a LINGUISTIC issue. When someone asks "Is length contraction >>> in SR physical?", they invariably don't have a definite meaning of >>> "physical" in mind (if they did, they could answer the question >>> themselves). Generally, they would consider a "physical length >>> contraction" to mean that the object ITSELF gets physically shorter. >>> This is manifestly not so in SR. But it is indeed what kenseto has >>> repeatedly failed to understand. >> >> The general public know what physical length means.....the length of a >> ruler is physical. > > You clearly haven't a clue. In SR, length is most definitely not > "physical" in the usual sense. In the USUAL sense, physical attributes > of an object do not change with the way someone looks at it. But the > length of an object DOES change with the way one looks at the object > (i.e. which inertial frame one uses to measure its length). The related > PHYSICAL attribute is proper length -- that is an attribute of an object > that is intrinsic to the object (and does not change with how one looks > at it -- it is an invariant). (...) Above you are *not* giving the USUAL (standarized) definition used in both science and engineering. I would recomend you a try to http://physics.nist.gov/cuu/Units/introduction.html specially the definition of *physical quantity*, the definition of *value of a physical quantity*, and the example of the height of the Washington Monument (h_W = 169 m) as physical quantity. Moreover, your claim that proper lenght is "an attribute of an object that is intrinsic to the object" is wrong, but I will be not discussing this now. -- http://www.canonicalscience.org/ BLOG: http://www.canonicalscience.org/en/publicationzone/canonicalsciencetoday/canonicalsciencetoday.html
From: "Juan R." González-Álvarez on 2 Feb 2010 14:23
kenseto(a)erinet.com wrote on Tue, 02 Feb 2010 09:54:48 -0800: (...) > Sure it is contradictory. > 1. Physical length is invariant as per the dictionary. 2. Physical > length is observer dependent as per SR . These are two contradictory > definition for Physical Length. Only if you insit on using the same term for denoting different concepts... P.S: Your argument involving "the dictionary" is excellent crackpot stuff. -- http://www.canonicalscience.org/ BLOG: http://www.canonicalscience.org/en/publicationzone/canonicalsciencetoday/canonicalsciencetoday.html |