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Natural Science Forum / Physics / Relativity / July 2008New version of a relativity FAQ
Hi folks A new version of the FAQ "Does mass increase with speed?" was written and is now online at http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html This is a well written article on this whole relativistic mass thing. The author makes a great point ------------------------------------------------------------------------------- A common argument against the use of relativistic mass is the fact that the equation E=mc^2 says that a body's relativistic mass equals its total energy, so why should we use two terms for what is essentially the same quantity? We should just stay with energy, and use the word "mass" to refer only to rest mass. But this argument neglects the definitions of the words mass and energy. Mass is a property of a body that we have an intuitive feel for; its definition as a resistance to acceleration is very fundamental. Energy, on the other hand, is defined in physics in rather ad hoc ways. Neither concept is even remotely understood by modern physics. ------------------------------------------------------------------------------- sniff sniff. I'm getting all misty at the quality of his writing :) To the author - Well done sir! Best wishes Pete > sniff sniff. I'm getting all misty at the quality of his writing :) > > To the author - Well done sir! Well, you see, Pete if you wanted to do any useful physics, like calculating the trajectory of a charged particle in a seprator, the "relativistic mass" is of no use to you, but \gamma*m_0 , where m_0 is the rest mass and \gamma=1/sqrt(1-(v/c)^2)) is instrumental. Along the same line, try calculating the mass of a photon gas cloud. I think that the "new" FAQ article is unfortunately very "retro" :-) On Jun 21, 8:21 pm, "Pmb" <peter.m.br...@somewhere.net> wrote: > sniff sniff. I'm getting all misty at the quality of his writing :) > > To the author - Well done sir! >Well, you see, Pete if you wanted to do any useful physics, like >calculating the trajectory of a charged particle in a seprator, the >"relativistic mass" is of no use to you, but \gamma*m_0 , where m_0 is >the rest mass and \gamma=1/sqrt(1-(v/c)^2)) is instrumental. And you think that's all there is to relativity? Wrong. The author changed it with a much better understanding of the subject than you have > On Jun 21, 8:21 pm, "Pmb" <peter.m.br...@somewhere.net> wrote: > [quoted text clipped - 8 lines] > > And you think that's all there is to relativity? I didn't say that. > The author changed > it with a much better understanding of the subject than you have You don't know that. Clearly. >> The author changed >> it with a much better understanding of the subject than you have > > You don't know that. Clearly. First off, I didn't mean that as an insult. If you took it that way that I apologize. I stated that because you provided the same old argument that has been provided for the last 20 years and that is an argument which is simply wrong. There is a very good reason that the FAQ was changed. Unfortunately the reasons are too complex/extensive to discuss in that FAQ. The author wanted to keep it simple and within SR only. However I can tell you the details if you're interested? As far as your question >Along the same line, try calculating the mass of a photon gas cloud. Its answered in a previous post and is trivial. But as far as the more complex question "What is the mass density of a gas cloud" I await your response. Pete On Jun 21, 8:21 pm, "Pmb" <peter.m.br...@somewhere.net> wrote: > sniff sniff. I'm getting all misty at the quality of his writing :) > > To the author - Well done sir! Well, you see, Pete if you wanted to do any useful physics, like calculating the trajectory of a charged particle in a seprator, the "relativistic mass" is of no use to you, but \gamma*m_0 , where m_0 is the rest mass and \gamma=1/sqrt(1-(v/c)^2)) is instrumental. --------------------------------------------------------------------- Einstein would disagree if the question were asked in terms of GR. Read his text "The Meaning of General Relativity" and see for yourself >Along the same line, try calculating the mass of a photon gas cloud. Its not what you think it is. If you calculate the total mass of the cloud then its inertial mass is proportional to the proper mass. The proper mass determined solely from the total energy as measured in the zero momentum frame. However if the cloud is not of finite size and you're looking for the mass density then I'll let you take a guess and see if you know what you're talking about >I think that the "new" FAQ article is unfortunately very "retro" :-) You're certainly entitled to your opinion. Too bad you're not finding out the reason for the change and basing your opinion only on the fact that it was changed. Big mistake Tell you what. Calculate the mass density of photon gas Calculate the inertial mass, and the proper mass, of a uniform magnetic field. Calculate the inertial mass and proper mass of a rod under stress. > On Jun 21, 8:21 pm, "Pmb" <peter.m.br...@somewhere.net> wrote: >> sniff sniff. I'm getting all misty at the quality of his writing :) [quoted text clipped - 6 lines] > the rest mass and \gamma=1/sqrt(1-(v/c)^2)) is instrumental. > --------------------------------------------------------------------- That's kind of a silly comment since \gamma=1/sqrt(1-(v/c)^2)) is iinsufficient to determine the world line of a particle in general since the mass is also required. And p = \gamma*m_0*v only holds under special circumstances Since you know all there is to know of this subject please give an example of when p = \gamma*m_o*v does not hold. Pete ps - Please don't get the idea that I'm insulting you. I never had that intention in mind. I'm criticizing you, which is very very different. I'm addressing only your knowledge, and not your person > Tell you what. Calculate the mass density of photon gas > > Calculate the inertial mass, and the proper mass, of a uniform magnetic > field. > > Calculate the inertial mass and proper mass of a rod under stress. I asked you first, let's see you do it :-) >> Tell you what. Calculate the mass density of photon gas >> [quoted text clipped - 4 lines] > > I asked you first, let's see you do it :-) I already did. You failed to be more precise so I gave you both responses. The (invariant) mass of a gas of photons equals the total energy, as measured in the zero momentum frame, over c^2. If you're talking about the mass density then you need to say that. You only said the mass. > I already did. You failed to be more precise so I gave you both responses. > The (invariant) mass of a gas of photons equals the total energy, as > measured in the zero momentum frame, over c^2. Correct. Now, let me show you a more elegant way of computing it without using any mass at all: http://www.savefile.com/files/1625448 I also asked you to compute the trajectory of a charged particle moving in a electro-magnetic field (E>0, B>0). >> I already did. You failed to be more precise so I gave you both >> responses. [quoted text clipped - 3 lines] > Correct. Now, let me show you a more elegant way of computing it > without using any mass at all: Calculate the mass without using the mass? That question doesn't even have a meaning! > http://www.savefile.com/files/1625448 > > I also asked you to compute the trajectory of a charged particle > moving in a electro-magnetic field (E>0, B>0). The trajectory is dependant on the field. Without stating the field the trajectory can't be given. Plus, I'm not someone who is here to do problems for you. I had asked you a question and you asked me to answer yours first. That has now been done. I await your response. Pete > >> I already did. You failed to be more precise so I gave you both > >> responses. [quoted text clipped - 6 lines] > Calculate the mass without using the mass? That question doesn't even have a > meaning! The photon is a massless particle , Pete. You didn't know that? > >http://www.savefile.com/files/1625448 > [quoted text clipped - 3 lines] > The trajectory is dependant on the field. Without stating the field the > trajectory can't be given. Let's make it easy for you. Make E=0 , B aligned with the z axis and the initial velocity of the particle of mass m and charge q aligned with the x-axis. > Plus, I'm not someone who is here to do problems > for you. Well, it's a challenge. I bet you cannot do it by using relativistic mass. Let's see you solve this simple problem. >> >> I already did. You failed to be more precise so I gave you both >> >> responses. [quoted text clipped - 21 lines] > the initial velocity of the particle of mass m and charge q aligned > with the x-axis. Trivial. Childs play. Its even on a web page that I constructed. Its there waiting for you to answer my question. >> Plus, I'm not someone who is here to do problems >> for you. > > Well, it's a challenge. I bet you cannot do it by using relativistic > mass. That's silly. You're attempting to prove something which is not meaning full. F = dp/dt = q[E + vxB] is the equation of motion where p = mv = gamma*m_0*v. Like so many people in the past you are once again repeating their flawed arguement that one can write the equation of motion as F = d(gamma*m)/dt = q[E + vxB] where m = proper mass and as such the "relativistic mass" never appears in the equation. The problem with that kind of arguement is that the relativistic mass *is* there. You simply didn't give it a symbol. Its M = gamma*m This is one of those problems in which the relativistic mass is proportional to the proper mass. That isn't always the case and its for that reason the new FAQ was created. >Let's see you solve this simple problem. I will not answer another question until you answer mine. I had already explained that to you. Continued refusal by you at this point will be ignored and taken as an indication that you simply can't answer the problem > >> "Dono" <sa...@comcast.net> wrote in message > [quoted text clipped - 43 lines] > kind of arguement is that the relativistic mass *is* there. You simply > didn't give it a symbol. Its M = gamma*m OK 1. So , what is m? (Hint : rest mass) 2. You provided the BEGINNING of the solution, you need to calculate the full differential equation. So, calculate d(gamma*m)/dt and set up the full differential equation. 3. Now, in order to have the trajectory, you need to SOLVE the equation. Do you think you can do that? > >Let's see you solve this simple problem. > > I will not answer another question until you answer mine. I had already > explained that to you. Continued refusal by you at this point will be > ignored and taken as an indication that you simply can't answer the problem You haven't solved anythingyet, you just STARTED solving the problem. Try solving it for real, ok? > You haven't solved anythingyet, you just STARTED solving the problem. > Try solving it for real, ok? Why don't you answer his question? He showed an effort. > [...] F = dp/dt = q[E + vxB] is the equation of motion where p = mv = > gamma*m_0*v. Like so many people in the past you are once again repeating [quoted text clipped - 3 lines] > kind of arguement is that the relativistic mass *is* there. You simply > didn't give it a symbol. [...] A better way of writing that is: F = dP/d\tau = Faraday(.,U) or in components: F_i = dP_i/d\tau = Faraday_ij U^i Where F is the 4-force, P is the 4-momentum, Faraday is the EM field tensor, and U is the 4-velocity. There's no "relativistic mass" anywhere, with a symbol or without one -- EVERY symbol in those equations is an invariant or the components of an invariant tensor (NONE of your symbols are invariant). This way is better because the underlying Lorentz symmetry is manifest. In your equation is it present, but is hidden extremely well. Exercise for the reader: prove that PMB's equation is Lorentz invariant. Then do so for mine. Hint: these are the same equation using different notation. I estimate about a page of algebra vs 1 line. After doing that exercise, think about how one would search for a Lorentz-invariant Lagrangian of a new theory of physics. Which concepts and notation would make that be easier? Note that this was precisely the problem facing the architects of the standard model; they did not use "relativistic mass".... Tom Roberts >> I already did. You failed to be more precise so I gave you both >> responses. [quoted text clipped - 5 lines] > > http://www.savefile.com/files/1625448 I just read that link.That's as old as the hills. I did that *years* ago and its been on my website ever since.Its amount the first thing someone learns when they're learning SR!! What you've calculated there is the invariant mass of a system of photons. Since that calculation can be done in any frame of reference whatsoever I choose the rest frame. In that frame the invariant mass is simply the energy/c^2. Just as I have already explained to you. My web page that describes this is at http://www.geocities.com/physics_world/sr/invariant_mass.htm See Eq. (6) Look at the bottom of that page to see the problems that arise with that definition in more complicated situations. Pet > >> I already did. You failed to be more precise so I gave you both > >> responses. [quoted text clipped - 7 lines] > > I just read that link. You couldn't have because: 1. It talks about something more complex than the problem I gave you 2. There is a counter associated with the downloads, there is no indication that you have downloaded the file. I thought that you were a religious man, right? I thought religious people don't lie. Why are you telling such a silly lie, Pete? >That's as old as the hills. I did that *years* ago and > its been on my website ever since. Couldn't be since it talks about something that doesn't exist on your website. I checked :-) Why would you post such silly lies? > What you've calculated there is the invariant mass of a system of photons. Nope, I didn't. But you wouldn't know since you didn't read the file :-) > My web page that describes this is at > > http://www.geocities.com/physics_world/sr/invariant_mass.htm > > See Eq. (6) Yes, it does. But this is not what the file that you didn't read is about :-) >> Tell you what. Calculate the mass density of photon gas >> [quoted text clipped - 4 lines] > > I asked you first, let's see you do it :-) I already did, i.e. ----------- The proper mass determined solely from the total energy as measured in the zero momentum frame. ---------- If E_0 is the total energy of the photon cloud as measured in the zero momentum frame then the invariant mass m_0 is given by E_0 = m_0*c^2. The inertial mass (aka relativistic mass) m is given by m = gamma*m_0 Your turn. :) Pete > On Jun 21, 8:21 pm, "Pmb" <peter.m.br...@somewhere.net> wrote: >> sniff sniff. I'm getting all misty at the quality of his writing :) [quoted text clipped - 18 lines] > the mass density then I'll let you take a guess and see if you know what > you're talking about Dono - I answered your question yesterday in this post. See above. Why did you ignore it and why didn't you respond to my questions? If you don't want to discuss the subject then I understand and as such I won't ask you more questions. Pete > > Well, you see, Pete if you wanted to do any useful physics, like > > calculating the trajectory of a charged particle in a seprator, the > > "relativistic mass" is of no use to you, but \gamma*m_0 , where m_0 is > > the rest mass and \gamma=1/sqrt(1-(v/c)^2)) is instrumental. > > --------------------------------------------------------------------- So, I keep asking you to use relativistic mass in order to calculate the trajectory of a charged particle in a (E,B) field and you keep giving the runaround. Is this because you are unable to do it? >> > Well, you see, Pete if you wanted to do any useful physics, like >> > calculating the trajectory of a charged particle in a seprator, the [quoted text clipped - 5 lines] > the trajectory of a charged particle in a (E,B) field and you keep > giving the runaround. Is this because you are unable to do it? Its because you refused to answer my question > >> > Well, you see, Pete if you wanted to do any useful physics, like > >> > calculating the trajectory of a charged particle in a seprator, the [quoted text clipped - 5 lines] > > the trajectory of a charged particle in a (E,B) field and you keep > > giving the runaround. Is this because you are unable to do it? Pete, There is a reason for asking you to solve the problem. Tom already tried to show you how the "relativistic mass" doesn't work very well in the context of more modern fields, like QED. His argument flew over your bald spot :-) I am challenging you to solve a simple electrodynamics problem using the concept of relativistic mass. This is not a quid pro quo in solving problems, this is an effective way of showing that your antiquated concepts are insufficient when it comes to solving modern problems. If you cannot do it, why don't you admit it and be done with it? Why give all this runaround? > Dono - I answered your question yesterday in this post. See above. Why did > you ignore it and why didn't you respond to my questions? If you don't want > to discuss the subject then I understand and as such I won't ask you more > questions. > > Pete We are past this , Pete You have been asked about 4 times to calculate the trajectory of a charged partcle in an electromagnetic field (E>0, B>0) by using relativistic mass. Stop trying to give the runaround :-) >> Dono - I answered your question yesterday in this post. See above. Why >> did [quoted text clipped - 9 lines] > charged partcle in an electromagnetic field (E>0, B>0) by using > relativistic mass. Stop trying to give the runaround :-) You refused to answer my question. Why on earth would I answer yours if you refuse to answer mine? The only reason I can think of is that you don't know the answer. And your question is incomplete. You didn't specify the field Dear Pmb: > Hi folks > [quoted text clipped - 23 lines] > sniff sniff. I'm getting all misty at the quality of > his writing :) How funny that we caution newbies not to let "intuition" and "common sense" guide them through relativity, then we splice the bullsh*t of a "mass" that is different to different axes of acceleration in as having an "intuitive feel". And try and justify it by glancingly referring to E=mc^2 (or even Newton's E = 1/2mv^2), which is *not* where the "intuitive feel" of mass comes from. 'Twas Mr. Koks' idea to resurrect this particular slant. > To the author - Well done sir! I just publish the links, I don't have to agree with them. Personally, I feel it to be a giant step backwards. It yields yet another arcane formulation that will stand between the newbie and understanding, with *none* of the "intuitive feel" sought. But hey, I am just a mechanical engineer. And I understand you (and Don) do not agree. David A. Smith > I just publish the links, I don't have to agree with them. Personally, I > feel it to be a giant step backwards.> That's due to your incomplete understanding of the subject matter. > And I understand you (and Don) do not agree. Wrong. That's more of a lie than being in error too since its absolutely wrong. Don and I agree very much. We have disagreed in the past on minor things but we always came to a common agreement and understanding. On everything as a matter of fact. Don certainly has a better understanding of the subject that you do that's for sure. There are more erroneous assertions that occur because of the other definition of mass than I care to list. Intuition is important. That's why terms are defined as such Dear Pmb: >> I just publish the links, I don't have to agree >> with them. Personally, I feel it to be a giant >> step backwards.> > > That's due to your incomplete understanding > of the subject matter. No, that is due to my having to explain it. Mass that is different for different directions of acceleration, is not the scalar quantity the newbie (and Newton) had in mind. >> And I understand you (and Don) do not >> agree. > > Wrong. That's more of a lie ... I left the sentence incomplete, and you assumed what I did not intend. I stated my opinion, then in this sentence I observed that you and Don did not agree (with me). Not each other. Pull your claws back in. David A. Smith > Dear Pmb: > [quoted text clipped - 8 lines] > different directions of acceleration, is not the scalar quantity the > newbie (and Newton) had in mind. Nonsesnse. I know of all of these arguements, seemingly much better than you do as a matter of fact. That has nothing to do with why it was changed. And your assertion that mass is different in different directions is based on an invalid assumption about how mass is defined. Mass is *not* defined as m = F/a. That is merely an equality which holds under special circumstances. Its accredited to Euler who stated it under special circumstances (constant mass motion). Newton defined mass as the m in p = mv and that's how its defined in relatity too. Proper mass is defined similarly in that P = m_0 U where P = 4-momentum, U = 4-velocity and m_0 = proper mass. That mass was a scalar quantity in Newtonian mechanics is not found in its definition. It is deduced from observation. Definitions need not be based on observations but only to describe a theory. If the theory changes that doesn't mean that the definitions need to change. The definition of 3-velocity never changed even though its transformation properties did. >>> And I understand you (and Don) do not >>> agree. [quoted text clipped - 4 lines] > stated my opinion, then in this sentence I observed that you and Don did > not agree (with me). Not each other. I noticed that you snipped off the important part. The whole thing read "That's more of a lie than being in error too since its absolutely wrong." Okay. Its not a lie. So you're merely understand. If you state something like "I understand.." then that is *not* an opinion, its an assertion. Please learn the difference. An opinion is something which is "a view, judgment, or appraisal formed in the mind about a particular matter". So what is your view? Tell me something - On what did you base your "understanding" about whether Don and I agreed or not? I'm sure the class would love to hear it! > Pull your claws back in. Oy! You're seeing claws where none exist. Trying to read my mind are you? So (Stuff) Dave - As I said to Dono; Please don't get the idea that I'm trying insulting you or put you down. I never had that intention in mind. I'm criticizing you, which is very very different. I'm addressing only your knowledge, and not your person. It seems that you assumed I was trying to insult you or that you thought I was attacking or getting emotional due to your response about the claws. That was never the case. If you want to know how I feel then ask me, please don't assume it. Don't try to be a mind reader. Okay? When I say that you don't understand the subject then that is not an insult but an evaluation of your knowledge based on the content of what you've posted. Pete ps - If you'd like to read what Don and I talked about I'd be more than happy to forward those e-mails to you if you get Don's permission. Don did point something out to me which I'm thankful for. It was more of reminding me of something I had forgotten at the moment. Don's a very smart man. Please give him more credit than you have. If you disagree with what he wrote then why don't you do something about it. I.e. e-mail him and relay your concerns. Dear Pmb: Have a nice Sunday. I refuse to have an argument with you today. David A. Smith > Dear Pmb: > > Have a nice Sunday. > > I refuse to have an argument with you today. No problem. I wasn't looking for one. I have a web page to create on the derivation on time dilation regarding an accelerating frame so my time is best spent there. Have a nice Sunday yourself David. Pete > Dear Pmb: > [quoted text clipped - 30 lines] > "mass" that is different to different axes of acceleration in as having an > "intuitive feel". As the FAQ points out at the end, "relativistic mass" has an intuitive feel and is NOT direction dependent. Of course force and acceleration are not along the same line, but that's how nature works and relativistic mass even gives an understanding of why this is the case. > And try and justify it by glancingly referring to E=mc^2 (or even Newton's > E = 1/2mv^2), which is *not* where the "intuitive feel" of mass comes > from. 'Twas Mr. Koks' idea to resurrect this particular slant. Actually, the FAQ misses the important point that since c is not constant in the way it was assumed in SRT, E and m are not only physically different entities, but they are in general not even proportional. http://groups.google.com/group/sci.physics.research/msg/dcd13814f4019d50 >> To the author - Well done sir! > > I just publish the links, I don't have to agree with them. Sure. If you find an error in the FAQ, just tell the author what the error is. However, if you find no error, there can be no scientific disagreement either. And if you can think of another advantage of invariant mass that isn't mentioned, you can ask him to add that in order to make it more balanced (but watch out for faulty arguments). > Personally, I feel it to be a giant step backwards. It yields yet another > arcane formulation that will stand between the newbie and understanding, > with *none* of the "intuitive feel" sought. But hey, I am just a > mechanical engineer. Instead I agree with Feynman that it is very helpful. Cheers, Harald | > Dear Pmb: | > [quoted text clipped - 53 lines] | Sure. If you find an error in the FAQ, just tell the author what the error | is. Ok. The error is: If the speed of light from A to B is c-v, and the speed of light from B to A is c+v, the "time" each way is NOT the same, DUMBFUCK! 1/2[tau(A)+tau(A')]= tau(B) where A = (0,0,0,t) A' =(0,0,0,t+x'/(c-v) +x'/(c+v)) B = (x',0,0,t+x'/(c-v)) x' = x-vt Ref: http://www.fourmilab.ch/etexts/einstein/specrel/www/figures/img22.gif "Easy: he did NOT say that." - cretin harald.vanlintelButNotThis@epfl.ch According to moron van lintel, Einstein did not write the equation he wrote. > As the FAQ points out at the end, "relativistic mass" has an intuitive feel > and is NOT direction dependent Yes. But that is inconsistent with the author's claim "its definition as a resistance to acceleration is very fundamental", as resistance to acceleration is NOT given by "relativistic mass" except in one specific case: magnetic force on a charged particle (i.e. 3-force is always perpendicular to 3-velocity). And worse, it is also inconsistent with the author's statement that "Mass is a property of a body" -- I agree with that particular statement, but disagree with the entire approach and conclusion of the page. > course force and acceleration are not > along the same line, but that's how nature works and relativistic mass even > gives an understanding of why this is the case I see no such "understanding" at all, merely ad-hoc equations. As I said before, this new version of this FAQ page misses the point entirely, and does not present the mainstream viewpoint adequately at all. In actual usage among physicists who use relativity daily, "mass" is an invariant, and "relativistic mass" is an anachronism. And the reason for this is completely absent in the webpage: kinematical terms and notation should incorporate the underlying symmetry, so the description of dynamics is simplified. Tom Roberts >> As the FAQ points out at the end, "relativistic mass" has an intuitive >> feel and is NOT direction dependent [quoted text clipped - 4 lines] > case: magnetic force on a charged particle (i.e. 3-force is always > perpendicular to 3-velocity). David repeated a collossal error of the old FAQ that now has been corrected. About the inconsistency, I partially agree; see my reply to your message. > And worse, it is also inconsistent with the author's statement that "Mass > is a property of a body" -- I agree with that particular statement, but > disagree with the entire approach and conclusion of the page. I'm afraid the page oscillates too much around neutral, let's hope the oscillation will fade. At least the big errors were removed. >> course force and acceleration are not along the same line, but that's >> how nature works and relativistic mass even gives an understanding of why >> this is the case > > I see no such "understanding" at all, merely ad-hoc equations. Those who never used the concept don't have the understanding that goes with it... > As I said before, this new version of this FAQ page misses the point > entirely, and does not present the mainstream viewpoint adequately at all. IMHO, opinions that are a matter of taste should not even be expressed in a science FAQ; moreover, it is debatable what "mainstream" is here (according to the recent stats I saw, it's rather equal). However, it does appear to be lacking explanation of the advantages of using invariant mass and I do agree that it needs to be more balanced. > In actual usage among physicists who use relativity daily, "mass" is an > invariant, and "relativistic mass" is an anachronism. That's what you say; I disagree. :-) > And the reason for this is completely absent in the webpage: kinematical > terms and notation should incorporate the underlying symmetry, so the > description of dynamics is simplified. That "should" is intolerant and based on taste, which is just what a science FAQ should avoid! Cheers, Harald Dear harry: ... >>> course force and acceleration are not along the >>> same line, but that's how nature works and [quoted text clipped - 6 lines] > Those who never used the concept don't have the > understanding that goes with it... Gentlemen, recall this is a FAQ. It is not a wiki entry. It is not a textbook section. It is not a product advertisement page. We are answering the questions of someone that does not know, or has forgotten. I suspect in these cases, that a single webpage cannot present all that is necessary to impart the necessary "understanding". David A. Smith > Dear harry: > [quoted text clipped - 16 lines] > I suspect in these cases, that a single webpage cannot present all that is > necessary to impart the necessary "understanding". Yes indeed - it can only summarize some of the main points. And in that respect, it appears to be now a bit lacking in mentioning the perceived benefits of the use of invariant mass. Almost certainly the author will be willing to elaborate a little more on that. Regards, Harald > Gentlemen, recall this is a FAQ. It is not a wiki entry. It is > not a textbook section. It is not a product advertisement page. > We are answering the questions of someone that does not know, or > has forgotten. > I suspect in these cases, that a single webpage cannot present > all that is necessary to impart the necessary "understanding". Yes. But I think the FAQ pages should present the mainstream terminology and understanding of physics, and not pander to a few loudmouth wannabes. "Relativistic mass" simply is not part of mainstream physics today, as a perusal of the relevant literature shows -- all references to usages of "relativistic mass" around here have been to TEACHING physics, not DOING physics. I think the FAQ page should say this. It should also refer to historical usages of "relativistic mass" and "mass varying with speed", and explain why those phrases are no longer used, and why "mass" today refers to an invariant. If they want to influence the terminology, advocates of "relativistic mass" should explain why it is better, in ways that count for DOING physics, not just teaching it. To start, they should display the Lagrangians for classical electrodynamics and QED using "relativistic mass", and show why they are better than the conventional methods (which use invariants). Absent that, they have no leg to stand on. Tom Roberts Dear Tom Roberts: >> Gentlemen, recall this is a FAQ. It is not a wiki >> entry. It is not a textbook section. It is not a [quoted text clipped - 4 lines] >> cannot present all that is necessary to impart >> the necessary "understanding". [the "understanding" was how to use relativistic mass without getting fried, and how to know when an author was referring to relativistic mass and not rest mass.] > Yes. But I think the FAQ pages should present > the mainstream terminology and understanding [quoted text clipped - 4 lines] > usages of "relativistic mass" around here have > been to TEACHING physics, not DOING physics. Arxiv.org filed last year (excluding Pete's paper) http://arxiv.org/abs/astro-ph/0702667 http://arxiv.org/abs/astro-ph/0702055 http://arxiv.org/abs/0709.3690 http://arxiv.org/abs/0708.4289 http://arxiv.org/abs/0707.2426 Granted they are not all doing particle physics, or trying to find a road between the classical and the discrete. ~56 total papers on file. > I think the FAQ page should say this. It should > also refer to historical usages of "relativistic mass" > and "mass varying with speed", and explain why > those phrases are no longer used, and why > "mass" today refers to an invariant. ... If for no other reason than "dimensional analysis". Collect the mass-associated terms separate from the velocity-associated terms... > If they want to influence the terminology, > advocates of "relativistic mass" should explain > why it is better, in ways that count for DOING physics, not > just teaching it. I don't think that needs to be in the page. > To start, they should display the Lagrangians > for classical electrodynamics and QED using > "relativistic mass", and show why they are > better than the conventional methods (which use invariants). > Absent that, they have no leg > to stand on. Maybe this "search for purity" is what drove Chris Hillman from the newsgroup. Tom I respect you, and your opinion. I think your objections are far beyond the needs / target-audience of a FAQ page. I find Pete's and harry's arguments uncompelling, and yours only marginally so. They like to have mass as m(v), because they find it "intuitively" attractive. I like to handle the velocity (as a vector) in the formulae (where I expect rules to be applied), and have mass as an invariant. Since this is not a holy war, let us define a webpage that is equally unsatisfying to both camps, or delete the web page. David A. Smith On Jun 23, 7:10 pm, "N:dlzc D:aol T:com \(dlzc\)" <dl...@cox.net> wrote: > Granted they are not all doing particle physics, or trying to > find a road between the classical and the discrete. ~56 total > papers on file. Dave, This is all nice an dandy EXCEPT when you start dealing with particle physics. Tom wrote: "A better way of writing that is: F = dP/d\tau = Faraday(.,U) or in components: F_i = dP_i/d\tau = Faraday_ij U^i " You can't solve the above by clinging to relativistic mass. I challenged Pete and he gave me one full day of runaround. On the other hand, the solution is quite straightforward in the fully invariant formulation, when relativistic mass "m" is replaced by \gamma*m_0 where "m_0" is the invariant mass. Dear Dono: > On Jun 23, 7:10 pm, "N:dlzc D:aol T:com \(dlzc\)" > <dl...@cox.net> [quoted text clipped - 6 lines] > This is all nice an dandy EXCEPT when you > start dealing with particle physics. Some of those papers are done by people that do particle physics. I ran into one on sci.astro, and he about chewed my ear off. ... > You can't solve the above by clinging to > relativistic mass. One formulation does not a theory make. Can you see: 1) I also dislike relativistic mass, and 2) It is purely a matter of taste? We will go around and around for another week, and no result will obtain, because ultimately IT DOESN'T MATTER. Whatever floats your boat, gives you the "intuitive feel" you think everyone should feel, that is what you are going to run up the flagpole. Nature could care less what mathematical gyrations you go through to get your answer. You could invoke an aether, phlogiston, stick pins in little dolls. Just get an answer, and let Her handle the rest. Now is this a community where everyone has a voice, has a say, or do we only preach one gospel? We can play it either way... but I think there *must* be room and tolerance for both. Seems to me better to display it, recognize it, and move on. David A. Smith On Jun 23, 7:39 pm, "N:dlzc D:aol T:com \(dlzc\)" <dl...@cox.net> wrote: > Some of those papers are done by people that do particle physics. > I ran into one on sci.astro, and he about chewed my ear off. Fine, can this guy solve any trajectory of a charged particle by using relativistic mass? This would be something short of a miracle. > ... > [quoted text clipped - 4 lines] > 1) I also dislike relativistic mass, and > 2) It is purely a matter of taste? Not really, I think it is a matter of usability. Relativistic mass is unusable in trying to solve the simple problem of charged particles moving in a (E,B) field > We can play it either way... but I think there *must* be room and > tolerance for both. Seems to me better to display it, recognize > it, and move on. > > David A. Smith Sure :-) > I find Pete's and harry's arguments uncompelling, .. You haven't heard mine yet. Pete Dear Pmb: >> I find Pete's and harry's arguments uncompelling, .. > > You haven't heard mine yet. Oh, has it changed in the last, what, five years? David A. Smith > Dear Pmb: > [quoted text clipped - 3 lines] > > Oh, has it changed in the last, what, five years? Very much so. Do you think that people stop learning for some reason? Pete Dear Pmb: >> Dear Pmb: >> [quoted text clipped - 6 lines] > Very much so. Do you think that people stop learning > for some reason? It is not a matter of "learning" on your part Pete, but an "obsession" on the "pro-relativistic mass side", and the penchant to speak about its "benefits" at every chance. I suppose every Don Quixote needs his windmill. David A. Smith > Dear Pmb: > [quoted text clipped - 12 lines] > the "pro-relativistic mass side", and the penchant to speak about its > "benefits" at every chance. The only obsession on my part was to learn the truth, regardless of what that meant. And that required painstaking research. But call it what you like. It makes no difference to me what you think in this respect > Arxiv.org filed last year (excluding Pete's paper) > http://arxiv.org/abs/astro-ph/0702667 That abstract includes the phrase "relativistic mass shift" -- this is not at all the same as "relativistic mass" in the sense PMB means it. This abstract is COMPUTING the mass of several ions using a RELATIVISTIC theory rather than the usual non-relativistic theory, and comparing the two computations. Their "relativistic mass shift" is the difference between the two theories, NOT anything at all related to the "relativistic mass" of a moving object. > http://arxiv.org/abs/astro-ph/0702055 This is a plasma paper, notable for the unusual need to include relativistic effects. > http://arxiv.org/abs/0709.3690 This is a completely new theory that is NOT relativity, and the use of "relativistic mas" is NOT what PMB means. In particular, the abstract discusses a change in the PROPER mass of an object, and says this "gets reflected in its relativistic mass". > http://arxiv.org/abs/0708.4289 This is a pedagogical paper. And its abstract states explicitly that the mass of the 2-photon system discussed is a relativistic invariant. > http://arxiv.org/abs/0707.2426 Thisis another pedagogical paper. > Granted they are not all doing particle physics, or trying to > find a road between the classical and the discrete. But NONE of them support the usage of "relativistic mass" except in TEACHING physics. >> If they want to influence the terminology, >> advocates of "relativistic mass" should explain >> why it is better, in ways that count for DOING physics, not >> just teaching it. > > I don't think that needs to be in the page. No. that is what such advocates need to do to influence the terminology physicists actually use. > Since this is not a holy war, let us define a webpage that is > equally unsatisfying to both camps, or delete the web page. IMHO small changes would satisfy me. It should state unequivocally how terminology is actually used, and relate that to historical usages. In some ways, methinks the author doth protest too much.... Tom Roberts Dear Tom Roberts: ... >>> If they want to influence the terminology, >>> advocates of "relativistic mass" should explain [quoted text clipped - 5 lines] > No. that is what such advocates need to do to > influence the terminology physicists actually use. That and actually make it work easier, for those applications. >> Since this is not a holy war, let us define a >> webpage that is equally unsatisfying to both [quoted text clipped - 3 lines] > should state unequivocally how terminology is > actually used, and relate that to historical usages. Pete, harry, would this be acceptable? > In some ways, methinks the author doth protest > too much.... David A. Smith > Dear Tom Roberts: > [quoted text clipped - 20 lines] > > Pete, harry, would this be acceptable? Sure, although I suspect that with "how terminology is actually used" Tom may have something else in mind as I do. And correct reference to historical usages is one of the improvements that I also suggested: the current FAQ still mixes up relativistic mass with the directional mass concepts that Lorentz and Einstein used. Cheers, Harald >> Dear Tom Roberts: >> [quoted text clipped - 20 lines] >> >> Pete, harry, would this be acceptable? Its actual usage is often wrong. That's the problem. people have the wrong idea about mass. A soundbite won't solve that problem Pete > Sure, although I suspect that with "how terminology is actually used" Tom > may have something else in mind as I do. And correct reference to [quoted text clipped - 4 lines] > Cheers, > Harald Dear harry and Pmb: ... > >>> IMHO small changes would satisfy me. It > >>> should state unequivocally how [quoted text clipped - 6 lines] > problem. people have the wrong idea about > mass. ... relativistic mass .... > A soundbite won't solve that problem Not looking for a soundbite solution, looking for an "answer" for a FAQ entry. Not a solution, just a description. I don't see the need for clear differentiation between rest mass and relativistic mass going away, and would need to be part of the entry. David A. Smith Dear harry and Pmb: On Jun 24, 10:41 am, "Pmb" <peter.m.br...@somewhere.net> wrote: > "harry" <harald.vanlintelButNotT...@epfl.ch> wrote in message > > news:1214325958_260@sicinfo3.epfl.ch... ... > >>> IMHO small changes would satisfy me. It > >>> should state unequivocally how [quoted text clipped - 6 lines] > problem. people have the wrong idea about > mass. >... relativistic mass .... nope. What do you know about mass density, the mass of a stressed body and time varying mass of an *extended* object? >> A soundbite won't solve that problem >Not looking for a soundbite solution, looking for an "answer" for a >FAQ entry. Not a solution, just a description. I'm happy with the FAQ accept with the "resitance to acceleration" thing. Pete Dear Pmb: > Dear harry and Pmb: > [quoted text clipped - 17 lines] > > nope. What do you know about mass density, "mass density"? Density is mass per unit volume. Other than that... > the mass of a stressed body and > time varying mass of an *extended* object? I know a little about deformable solids, and the storage of energy in deformation of extended bodies. These energies are very small, and discussion of "mass gain" essentially are beneath the ability to measure. Order of magnitude, about what you would expect for a "mass gain" by heating a body. David A. Smith Dear Pmb: On Jun 24, 11:08 am, "Pmb" <peter.m.br...@somewhere.net> wrote: > "dlzc" <dl...@cox.net> wrote in message > [quoted text clipped - 18 lines] > > nope. What do you know about mass density, >"mass density"? Density is mass per unit volume. Other than that... To define mass density one first has to define mass. If you are going to use "rest mass" then that becomes a problem. Here is an example http://www.geocities.com/physics_world/sr/mass_mag_field.htm This is also why Dono refused to respond - I doubt he ever considered something like this. This problem (mass density of a magnetic field) is in Ohanian's new SR text. > the mass of a stressed body and > time varying mass of an *extended* object? I know a little about deformable solids, and the storage of energy in deformation of extended bodies. These energies are very small, and discussion of "mass gain" essentially are beneath the ability to measure. Order of magnitude, about what you would expect for a "mass gain" by heating a body. =================== A stressed body is not related to its momentum as p = gamma*v (m = rest mass) An extended body which has a time varying mass also does not have its momentum related to its rest mass as p = gamma*v Hence my comments about the usage of rest mass. > This is also why Dono refused to respond - I doubt he ever considered > something like this. I responded. Right here: http://groups.google.com/group/sci.physics.relativity/browse_frm/thread/e70f2f44 e272db52/4875fd36f655bcc3#4875fd36f655bcc3 > Dear Pmb: > [quoted text clipped - 49 lines] > > Hence my comments about the usage of rest mass. I made an example of this too. See the bottom of this page after "An Incorrect Application of Proper Invariant Mass " (Title is wrong. The term "Invariant " shouldn't be in there) http://www.geocities.com/physics_world/sr/invariant_mass.htm > Dear Pmb: > [quoted text clipped - 49 lines] > > Hence my comments about the usage of rest mass. General question (not necessarily to David): Has Dono accepted my challenge? :) > > Dear Pmb: > [quoted text clipped - 54 lines] > > - Show quoted text - Yes, I even answered by correcting the many errors in your solution: http://www.geocities.com/physics_world/sr/cyclotron.htm You need to take your blinders off, Pete, the errors are quite embarassing. Pmb wrote on Tue, 24 Jun 2008 19:26:01 -0400: > General question (not necessarily to David): Has Dono accepted my > challenge? :) Pete, you already met Dono previously and he lied you. But then Dono was using another nickname. http://groups.google.com/group/sci.physics.relativity/msg/3e85302f61a6aae3 http://groups.google.com/group/sci.physics.relativity/msg/d5d8d8561738eba3 Dono continues using the same old tactics and insults as then and would caught now.  SignatureCenter for CANONICAL |SCIENCE) http://canonicalscience.org > Pmb wrote on Tue, 24 Jun 2008 19:26:01 -0400: > [quoted text clipped - 10 lines] > Dono continues using the same old tactics and insults as then and would > caught now. Whoa! Are you saying that Dono and Bilge are one in the same person? Pete Pmb wrote on Wed, 25 Jun 2008 05:17:21 -0400: >> Pmb wrote on Tue, 24 Jun 2008 19:26:01 -0400: >> [quoted text clipped - 7 lines] >> >> http://groups.google.com/group/sci.physics.relativity/msg/ d5d8d8561738eba3 >> Dono continues using the same old tactics and insults as then and would >> caught now. > > Whoa! Are you saying that Dono and Bilge are one in the same person? Don't sure about that because once Dono simulated be a hundred of different people before being caught in public by group administrators. But Dono is the same Karandash saying nonsense about potentials energy and you correcting all them (Bilge, Bill Hobba, Eric Gisse, Kanrandash- Dono) at once in that thread. The own Dono recognized he is Karandash a few days ago when i put a simple trap to him. You already had a bunch of discussion with Dono (aka Karandash) on the topic of relativistic mass. He is using now the same 'arguments' like that of "massless photons" http://groups.google.com/group/sci.physics.relativity/msg/a34886e54628677e http://groups.google.com/group/sci.physics.relativity/msg/d5d7d4c133c836e8 that Dono (aka Karandash) used in the past http://groups.google.com/group/sci.physics.relativity/msg/8376b187b2893a2d http://groups.google.com/group/sci.physics.relativity/msg/d97567213c1a51d7 http://groups.google.com/group/sci.physics.relativity/msg/95050b81f3f5d5c5 He is lying you again Pete. Have care. You also asked then, "is karandash and androcles one in the same person?" http://groups.google.com/group/sci.physics.relativity/msg/99288021878f57c5 Since Karandash is Dono, the question is today: are Dono and androcles the same person? Dir has also asked to dono: "Are you Androcles in disguise?" http://groups.google.com/group/sci.physics.relativity/msg/a133d3ab0c7dab89 and after reading Dono reply then assured that Dono acts exactly as Androcles: http://groups.google.com/group/sci.physics.relativity/msg/2995518406a7977e Maybe then bilge Karandash dono and androcles are the same person i don't know. I am helping you on this bizarre stuff of who he is because you kindly help when I was attacked. My advice is that you would just ignore him and others and continue with your work. SignatureCenter for CANONICAL |SCIENCE) http://canonicalscience.org On Jun 25, 1:59 am, "Juan R." González-Álvarez <juanREM...@canonicalscience.com> wrote: [snip] Why are your past posts disappearing? Good thing you can't delete posts that aren't yours. Eric Gisse wrote on Wed, 25 Jun 2008 03:53:13 -0700: (snip) Your mistakes were corrected by me and Pete in above cited links. You may read both me and Peter arguments and extra info. I recommend you to learn something from above. You may also find useful information on http://canonicalscience.blogspot.com/2007/07/generalized-potential- energy.html where some other strong mistakes from you are corrected. SignatureCenter for CANONICAL |SCIENCE) http://canonicalscience.org "Juan R." González-Álvarez wrote on Wed, 25 Jun 2008 13:18:10 +0200: > Eric Gisse wrote on Wed, 25 Jun 2008 03:53:13 -0700: > [quoted text clipped - 11 lines] > > where some other strong mistakes from you are corrected. After noticing several people here confounding the f in (f = ma) with the F in (F = dp/dt) It is possible i will write a micro-thought about forces and equations of motion. It would include some extra remarks on well-known PUNS by tom. SignatureCenter for CANONICAL |SCIENCE) http://canonicalscience.org On Jun 25, 4:23 am, "JuanShito R." González-Álvarez <juanREM...@canonicalscience.com> wrote: > After noticing several people here confounding the f in > [quoted text clipped - 3 lines] > > (F = dp/dt) Embarassing attempt at covering up, Shito :-) > After noticing several people here confounding the f in > (f = ma) > with the F in > (F = dp/dt) Dont forget the f' in f'=ma for rotating systems, and the f" in f"=ma for linearly accelerated systems, and the f''' in f'''=ma for helically accelerated systems, and ... What good does such extended and non-standard notation do? The underlying equation, valid in all cases of Newtonian mechanics, is F=dp/dt (there's a similar equation for SR and GR). Taking some piece of the time derivative, christening it as a "force" and moving it to the left hand side and re-labeling that side with a new type of "f" does nothing useful, and is practically guaranteed to confuse people [#]. Note that in EVERY case the "force" involved is not directly measurable (measuring a force directly requires a two-terminal device, but such "forces" never have a second reference point). [#] Just note how many people are still confused by "centrifugal and Coriolis force", and those are several centuries old. Tom Roberts >> After noticing several people here confounding the f in >> (f = ma) [quoted text clipped - 6 lines] > > What good does such extended and non-standard notation do? Well, you have a point but so does he, see further. > The underlying equation, valid in all cases of Newtonian mechanics, is > F=dp/dt (there's a similar equation for SR and GR). The IDENTICAL equation in SR (valid in all cases) was probably part of nearly every physics course in the eighties. > Taking some piece of the time derivative, christening it as a "force" and > moving it to the left hand side and re-labeling that side with a new type > of "f" does nothing useful, and is practically guaranteed to confuse > people [#]. Note that in EVERY case the "force" involved is not directly > measurable (measuring a force directly requires a two-terminal device, but > such "forces" never have a second reference point). Interesting! I haven't thought about that, but at first sight that is only true for gravity. Here's a counter suggestion (assuming that we call the use of Hooke's law "directly"): W /\/\/\/\/\ S O -> W= wall /\/\/\/\/\ = spring S = sensor O = object > [#] Just note how many people are still confused by > "centrifugal and Coriolis force", and those are several > centuries old. Indeed - and that's due to NewSpeak. No such confusion existed with Newton. Cheers, Harald >> The underlying equation, valid in all cases of Newtonian mechanics, is >> F=dp/dt (there's a similar equation for SR and GR). > > The IDENTICAL equation in SR (valid in all cases) was probably part of > nearly every physics course in the eighties. It is not "identical" -- the symbols have different meanings (3-vectors => 4-vectors, time coord. => proper time). >> Taking some piece of the time derivative, christening it as a "force" and >> moving it to the left hand side and re-labeling that side with a new type [quoted text clipped - 5 lines] > Interesting! I haven't thought about that, but at first sight that is only > true for gravity. Not true. Consider trying to "measure" the "centrifugal force" on the popcorn stand next to a rotating carousel, in the carousel's coordinates. That "force" is truly enormous (mega Newtons or more), but the booth attendant is completely unaware of it. It is, of course, a pure artifact of the rotating coordinates. Or more to the point, how could one possibly measure "v*dm/dt" as a FORCE? To what would one connect the two terminals of the sensor? Tom Roberts >>> The underlying equation, valid in all cases of Newtonian mechanics, is >>> F=dp/dt (there's a similar equation for SR and GR). [quoted text clipped - 4 lines] > It is not "identical" -- the symbols have different meanings (3-vectors => > 4-vectors, time coord. => proper time). No, those physics courses used 3-vectors. >>> Taking some piece of the time derivative, christening it as a "force" >>> and moving it to the left hand side and re-labeling that side with a new [quoted text clipped - 5 lines] >> Interesting! I haven't thought about that, but at first sight that is >> only true for gravity. > Not true. Consider trying to "measure" the "centrifugal force" on the > popcorn stand next to a rotating carousel, in the carousel's coordinates. > That "force" is truly enormous (mega Newtons or more), but the booth > attendant is completely unaware of it. It is, of course, a pure artifact > of the rotating coordinates. I don't consider recognized artifacts and don't call them forces. > Or more to the point, how could one possibly measure "v*dm/dt" as a FORCE? > To what would one connect the two terminals of the sensor? No, an equality is not an identity - it is F that one can measure in certain situations. Please comment on my counter example. Harald Tom Roberts wrote on Wed, 25 Jun 2008 15:22:36 +0200: >> After noticing several people here confounding the f in (f = ma) >> with the F in [quoted text clipped - 3 lines] > for linearly accelerated systems, and the f''' in f'''=ma for helically > accelerated systems, and ... This straw man argument is fantastic and clearly indicates you did not understand the utility for (F = dp/dt) and the utility for (f = ma). > What good does such extended and non-standard notation do? No hope to you to understand this. But for the rest of people i will write something about the use of F F = dp/dt == \partial V / \partial q the use of f f = ma == m {{r,H},H} where "==" mean defined and the use of Q forces, defined on F. E. Udwadia; R. E. Kalaba. Analytical dynamics: a new approach. (1996). See definition of Q on http://canonicalscience.blogspot.com/2007/07/generalized-potential- energy.html > The underlying equation, valid in all cases of Newtonian mechanics, is > F=dp/dt (there's a similar equation for SR and GR). This remark is of not help. There is not need to repeat this because already was noticed in Micro- thoughts before, including generalizations of that equation *beyond* SR and GR. See for instance http://canonicalscience.blogspot.com/2007/08/relativistic-lagrangian-and- limitations_20.html The second canonical equation after "the classical equations of motion are derived from a natural covariant generalization of the Hamiltonian equations" defines a F force cannot be derived from SR or GR. That relativistic force F is being used to model relativistic many-body phenomena beyond SR and GR. > [#] Just note how many people are still confused by "centrifugal and > Coriolis force", and those are several centuries old. Good remark. Your traditional confusion regarding those forces will be also addressed in some way, with useful references (you do not know obviously) on certain research programs listed. SignatureCenter for CANONICAL |SCIENCE) http://canonicalscience.org "Juan R." González-Álvarez wrote on Thu, 26 Jun 2008 13:28:30 +0200: For axiomatic rigor better rewrite some equations. > F = dp/dt == \partial V / \partial q dp/dt = F == \partial V / \partial q > f = ma == m {{r,H},H} ma = f == m {{r,H},H} > This remark is of not help. This remark is of no help. SignatureCenter for CANONICAL |SCIENCE) http://canonicalscience.org On Jun 26, 4:36 am, "JuanShito R." González-Álvarez <juanREM...@canonicalscience.com> wrote: > "Juan R." González-Álvarez wrote on Thu, 26 Jun 2008 13:28:30 +0200: > [quoted text clipped - 7 lines] > > ma = f == m {{r,H},H} Still trying to cover up the monumental gaffe of thinking that f=ma can be used in relativity, JuanShito? On Jun 26, 4:36 am, "JuanShito R." González-Álvarez <juanREM...@canonicalscience.com> wrote: > "Juan R." González-Álvarez wrote on Thu, 26 Jun 2008 13:28:30 +0200: > [quoted text clipped - 14 lines] > -- > Center for CANONICAL |SCIENCE) http://canonicalscience.org Juanshito, Still trying to cover up the idiocy you came up a few days ago? On Jun 25, 3:18 am, "Juan R." González-Álvarez <juanREM...@canonicalscience.com> wrote: > Eric Gisse wrote on Wed, 25 Jun 2008 03:53:13 -0700: > [quoted text clipped - 14 lines] > -- > Center for CANONICAL |SCIENCE) http://canonicalscience.org Now explain how this post is a relevant response to: Why are your past posts disappearing? Good thing you can't delete posts that aren't yours. Eric Gisse wrote on Wed, 25 Jun 2008 05:32:45 -0700: (snip) You may correct your mistakes and learn some physics or you may continue by that way, you choose. SignatureCenter for CANONICAL |SCIENCE) http://canonicalscience.org On Jun 26, 3:39 am, "Juan R." González-Álvarez <juanREM...@canonicalscience.com> wrote: > Eric Gisse wrote on Wed, 25 Jun 2008 05:32:45 -0700: > [quoted text clipped - 5 lines] > -- > Center for CANONICAL |SCIENCE) http://canonicalscience.org Another irrelevant reply. If you don't want to explain why you are going through the google archive and deleting your posts, just don't reply. > Whoa! Are you saying that Dono and Bilge are one in the same person? > > Pete Ok, I had a look at your solution : http://www.geocities.com/physics_world/sr/cyclotron.htm No wonder you were so cagey in sharing it, there are quite a few mistakes. I hope that you will take the following as constructive criticism and that you'll correct the page. Here it goes: 1.It is quite clear that you can't solve the problem by using relativistic mass, the "m" in your equations is rest mass. The reason is quite simple, starting from eq.1 you should be writing: d(\gamma*m*v)/dt=q(E+vxB) 2. You keep avoiding writing the ODE above, instead you go through all kinds of girations and you arrive to... 3. ....the following commedy of errors: "From the diagram it is easy to see that a positive charge q moves in a clockwise motion around the circle. w is known as the cyclotron frequency. To find an explicit expression for w we start with the expression for the magnitude of the Lorentz force which is F = qvB. Since the motion is transverse to the acceleration we also have F = ma = mRw2 = qvB = qRwB or w = mv/qB = p/qB. " 4. You are now mixing relativity with Newtonian mechanics (F=ma), exactly like Juanshito did earlier in this thread. This is a "no-no". You simply cannot have any "F=ma" in a relativistic page, if you want to be taken seriously. 5. This is the first time that mass, "m" appears in your solution (it should have appeared from the very beginning, in eq.1) but you were too focused on avoiding it. If you had it early on, in the ODE d(\gamma*m*v)/dt=q(E+vxB), you would have avoided this embarassing error. 6. Now, as a result of the error at point 4, you have a completely wrong formula for the "cyclotron frequency". Contrary to what you derived, w |
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