Teaching vs Doing: The Role of Concepts in Research - Insights from Physics

[pmb_phy]

In the past we've talked about ideas that people use in relativity. Some hold that in some cases there are some research physicists who have taught something that they use in their own research. Do you find that to have ever been true in any case? Why would they do that , i.e. teach a concept but never use it themselves?

(the actual examples of concepts I have in mind are irrelavent to this question I think and I don't mention it because it would detract from the question I'm more interested in)

Thanks

Pete

 

[mahesh_2961]

hai ,
i think the theories of the 20 th century are more or less "theories" than one which we can see -and-understand, like the theory of relativity speaks about time as a fourth dimension which is quite difficult to sink in .. similarly the Quantumn theory and Dual nature of electrons ..
so i think the method used in research is to build from those things which one is quite sure of .. and there are a lot of people who doesn't agree with the credibility of relativity theory proposed by Einstein..

regards
Mahesh

 

[ZapperZ]

hai ,
i think the theories of the 20 th century are more or less "theories" than one which we can see -and-understand, like the theory of relativity speaks about time as a fourth dimension which is quite difficult to sink in .. similarly the Quantumn theory and Dual nature of electrons ..
so i think the method used in research is to build from those things which one is quite sure of .. and there are a lot of people who doesn't agree with the credibility of relativity theory proposed by Einstein..

regards
Mahesh

Wait... Did I understand you correctly? It appears that you are implying that quantum theory and special relativity, are some "esoteric" ideas that do not get "used" or applied very often. Before I jump all over this, is this really what you are trying to say?

Zz.

 

[ZapperZ]

Some hold that although research physicists may teach something they don't use it in their own research. Do you find that to be true? Why would they do that , i.e. teach a concept but never use it themselves?

I find that to be completely false. Who is this "some" people and what made them (and you) think they have an accurate representation of what "research physicists" do?

Zz.

 

[pervect]

In the past we've talked about ideas that people use in relativity. Some hold that although research physicists may teach something they don't use it in their own research. Do you find that to be true? Why would they do that , i.e. teach a concept but never use it themselves?

This sounds like specialization to me.

Someone involved in a particular specialized area of research probably doesn't use every tool in his toolbox. This doesn't mean that students don't need a general set of tools.

 

[Stingray]

Given Pete's past posts, I'm going to take a guess that he's not referring to specialization. Anyways, there are occasionally concepts which might make it easier to introduce a subject, but aren't really useful once you understand things better. Also, certain concepts seem to stick around in introductory classes mostly for their "wow" factor. You want to keep people interested and motivate them to eventually learn more, but you don't really have the time to do things 'properly.'

Another issue which might cause some confusion is that different physicists are happy with very different levels of rigor even in their research. So what one person might teach as a rigorous result, another might view as speculation. This comes up even among the "big" names in relativity, and I assume the same thing happens in other fields as well.

 

[Gonzolo]

Do philosophers and historians "use" what they teach? Are all political science professors politicians? Nursing professors nurses? Do all business professors have a business? It's great if they do or had the experience but if he or she can teach the student to use the tools, that's what counts.

Even though Stephen Hawking probably uses GR and QM more than friction force on an inclined plane, I'd take his word for the inclined plane, you know he's been there.

There is a core curriculum for physics education, yet each professor must have a specialization, so some compromises are necessary. When professors only teach you what they use, it narrows your own possibilities.

 

[dextercioby]

Do philosophers and historians "use" what they teach? Are all political science professors politicians? Nursing professors nurses? Do all business professors have a business? It's great if they do or had the experience but if he or she can teach the student to use the tools, that's what counts.
Even though Stephen Hawking probably uses GR and QM more than friction force on an inclined plane, I'd take his word for the inclined plane, you know he's been there.
There is a core curriculum for physics education, yet each professor must have a specialization, so some compromises are necessary. When professors only teach you what they use, it narrows your own possibilities.

Couldn't agree more.Strict specialization within area of interest/research should not interfere with the pedagogical role the professor has.For example:let's say X is working really hard in QFT on curved spacetime.Yet,that should not prevent him from teaching (if asked,or imposed by the faculty where he works) let's say,solid state phyiscs or thermodynamics and statistical physics.Or,why not classical mechanics.It shouldn't be any problem whatsoever for a well prepared teacher,with a vast physical culture,but for one who doen't see anything but spinors,vielbeins and spin connections,it would be a tremendous effort speaking for 2 hours about the various formulations of the first principle of thermodynamics,or why not about Kepler problem in Newton's approach.I believe the ones that can do this easily-leave the office where on the table he has a bunch of papers full of tensors,go the class/lecture hall speak about something "ridiculously easy" and then come back in the office to get another glimpse at those tensors-are the real good professors,of which any university should be proud of.

I want to be that kind of proffessor that day.

Daniel.

 

[pmb_phy]

I find that to be completely false. Who is this "some" people and what made them (and you) think they have an accurate representation of what "research physicists" do?

Zz.

I was hoping to let the question rest on its original wording. The particular example I have in mind has always led to heated debates and I'm not interested in discussing the topic itself (I'm trying to avoid it actually).

As far as what "research physicists" do - I go by what I read in the physics literature plus my own experience in my own research efforts. That is the window I'm referring to. Any question about who does what and how gets into statistics. There are no stats pertaining to such things so one takes a glance at the physics literatrure. But then again each area of the physics literature is different. There are journals like Phys. Rev. D, Am. J. Phys., New Perspectives in Physics etc. The first reports research in the area of particles and fields. The purpose of the second journal mentioned (AJP) is to give valuable insight to graduate and undergraduate teachers and students of physics, aid in learning physics and discusses new ways of understanding, demonstrating and describing or teaching physics. The purpose of the last is to "convey to a broad spectrum of readers a deeper understanding and appreciation of the way physics is conducted, of its content and application, and of the profound influence that physics has had in changing our conception of the natural world and in shaping our modern scientific and technological culture."


Pete

 

[ZapperZ]

As far as what "research physicists" do - I go by what I read in the physics literature plus my own experience in my own research efforts. That is the window I'm referring to. Any question about who does what and how gets into statistics. There are no stats pertaining to such things so one takes a glance at the physics literatrure. But then again each area of the physics literature is different. There are journals like Phys. Rev. D, Am. J. Phys., New Perspectives in Physics etc. The first reports research in the area of particles and fields. The purpose of the second journal mentioned (AJP) is to give valuable insight to graduate and undergraduate teachers and students of physics, aid in learning physics and discusses new ways of understanding, demonstrating and describing or teaching physics. The purpose of the last is to "convey to a broad spectrum of readers a deeper understanding and appreciation of the way physics is conducted, of its content and application, and of the profound influence that physics has had in changing our conception of the natural world and in shaping our modern scientific and technological culture."

Pete

Pardon me, but this is nothing more than aimless rambling that does not even address my question. You haven't shown anything in which the people who are teaching stuff are actually NOT using them.

I took classes in solid state physics and condensed matter physics in which the respective instructors not only are experts in those subjects, but damn well make use of them! And these are very specific subjects too. We haven't even talk about more general area such as QM, E&M, etc... in which you'd better damn well know them to even work in any area of physics.

So I am still waiting for what is being taught in physics in which these researchers are not really using.

Zz.

 

[Gonzolo]

So I am still waiting for what is being taught in physics in which these researchers are not really using.

Zz.

I believe that all that is taught in physics is being used (more "advanced/specialized" versions of it anyway), but not necessarily by the specific professor who teaches it to us. A high school teacher first taught me about synchrotrons and nuclear powerplants, yet he's been a teacher all his life. And a professor doesn't necessarily need all 4 of MB, photon, BE, and FD statistics in his research but may well teach them all. Math profs show us how to solve differential equations, yet I would believe that they would rather solve the unsolved for their research, not the classics they have to teach students.

 

[pmb_phy]

You haven't shown anything in which the people who are teaching stuff are actually NOT using them.

I can't since I don't hold that to be true. I hold that people use what they teach.

So I am still waiting for what is being taught in physics in which these researchers are not really using.

Sorry. But I can't help you there since I don't believe it to be true. The question stated

Some hold that although research physicists may teach something they don't use it in their own research. Do you find that to be true? Why would they do that , i.e. teach a concept but never use it themselves?

I am not one of the "some" of those people.

I suppose I can't get around this. Please do not let this be a disucssion on the topic that I'm mentioning.

When the topic of mass comes up people will often say things like someone said the today in another forum, i.e. science doesn't use the terms anymore referring to the what some call relativistic mass. I replied

That is also incorrect. The concept is widely used. For example;

And gave a huge list of examples from relativity texts, physics journals, university relativity online lecture notes, links to particle accelerator labs etc. The response to that was

But I don't see how you can contend that you are presenting the viewpoint of the "relativity community" with a list of college intro courses, beginner's textbooks and the above list of journal articles - the American Journal of Physics is not a research journal, it is a teaching journal.

I've seen people argue like this all the time. Yet none of them have ever backed their claim up or made an attempt to. Ssince you can't prove a negative its impossible to attempt to prove. Since it can't be proved I wanted to know how people came to believe that relativists will write textbooks with the concept of relativistic mass and yet not use it themselves.

Since that discussion always goes off into a heated debate I didn't want to mention it. However it appears to me that people are not getting my point so this is meant to merely be a real life example.

I was assuming some of you believe the same thing the person I quoted above believes.

I'll rephrase my question with that example in mind

In the past (e.g. this morning in another forum) people have talked about ideas that people use in relativity (i.e. relativistic mass). Some hold that although research physicists may teach relativistic mass they don't use it in their own research. Do you find that to be true? Why would you think they would do such a thing, i.e. teach a concept but never use it themselves?

I hope this does not degenerate into a disucssion about rel-mass and whether its used blah blah blah.

Pete

 

[dextercioby]

I honesly believe that teching physics is a proffession,just like any other.I mean,it's okay to like/dislike some parts of it,some concepts ("relativistic mass" is just an example),but you have to keep in mind that u're being paid by the state (in most cases) to deliver to students NOT WHAT U LIKE,NOT WHAT U HATE OR THINK OF AS BEING IRRELEVANT,but what most physics teachers would teach their students worldwide,on the same subject,of course.Personal opinions should not be stated to students.The interesting subject with "relativistic mass" can be seen as an example of (wrongly) mixing personal beliefs/habits with the theory itself.E.g.a teacher is a researcher in QFT.Yet he's asked to teach a course on relativistic electrodynamics/special/general relativity.He would be virtually an idiot if he was to tell his students:"Well,guys,relativistic mass is not an important concept.Rest mass is hyperrelevant,as it's constant in every possible situation."I assume this would have come from him working in QFT where only 'rest mass' is relevant in the sense that for 'relativistic mass' he uses 'energy'.Yet,when discussing a theory,each and every concept is relevant for the theory itself and generalizations should be avoided,because,in most cases,they express (wrong) personal opinions.

Daniel.

PS.Great example,PETE.
PPS.And to answer your question,YES,people working in Q theory never use the concept of "relativistic mass".They use "energy" (zero-th component of the energy-momentum 4-vector).Einstein is held responsable for that.Though he had 0 contribution to QFT.

 

[Nereid]

Pete, I'm pretty sure I know what you're interested in, and I won't comment on that specifically.

In my experience, those who do research tend to start with what they were taught, i.e. the methods that were popular at the time they were doing the doctorates. Fairly quickly they develop - for themselves - somewhat idiosyncratic approaches; when writing papers, they use the approaches and styles that similar papers are written in.

Teachers vary widely ... some 'simply' reuse what they themselves were taught (with a few minor tweaks as the years go by); others try to keep current, and will adapt and adopt as fads and understanding changes. Of course, if choice of 'textbooks' is not theirs to make, they will have to use the approaches of the materials they are required to teach to.

However, unless there's some pretty clear 'sea-change', older approaches may live on for decades. For example, I've seen the origin of the solar system presented as 'a passing star pulled out material from the Sun which subsequently cooled and condensed into planets' (true story, honest! it was a junior high school teacher, and a substitute at that).

 

[ZapperZ]

In the past (e.g. this morning in another forum) people have talked about ideas that people use in relativity (i.e. relativistic mass). Some hold that although research physicists may teach relativistic mass they don't use it in their own research. Do you find that to be true? Why would you think they would do such a thing, i.e. teach a concept but never use it themselves?

I hope this does not degenerate into a disucssion about rel-mass and whether its used blah blah blah.

Pete

But this doesn't hold water as far as generalizing the "principle" that people don't use what they teach. I mean, how often does one actually encounter a situation that requires the use of relativistic mass?! Why can't we pick on, let's say, Coulomb's law? Now how many researchers use that, and use that often, do you think?

The thing is that you picked an esoteric example (or these people you "hang" around with) and asked how many actually use these things. When you find that it isn't many, you then feel compelled to make a generalized statement (question?) that professors teach stuff they don't actually use in their research. There is a serious FLAW in logic here.

And for whatever it is worth, I used to teach about relativistic mass, and I currently USE relativistic mass for the dynamics in the particle accelerator that I work with. So the assumption that scientists who teach relativistic mass do not use it in their research can be safely thrown out of the window.

This thread should be put to rest the same way all the other false assumptions about physics and physicists.

Zz.

 

[Andrew Mason]

This thread should be put to rest the same way all the other false assumptions about physics and physicists.

Which are not dissimilar to false general assumptions about, say, the law and lawyers.

AM

 

[Stingray]

So I did interpret your question correctly. Some of my previous statements apply to relativistic mass. It should also be noted that some physicists find the concept very useful, whereas others see it as an anachronism. This is personal taste. So a professor might introduce a concept that he doesn't like just because it is something you need to know to understand what certain people are saying. It might even be just for historical interest.

 

[pmb_phy]

But this doesn't hold water as far as generalizing the "principle" that people don't use what they teach.

Please reread the original post. I rephrased it.

In the past we've talked about ideas that people use in relativity. Some hold that in some cases there are some research physicists who have taught something (text or class) that they don't use in their own research. Do you find that to have ever been true in any case? Why would such a research do that, i.e. teach a concept but never use it in their research themselves?

The question I want to ask is does not pertain to the validity of such accusations. It pertains to the question regarding why some people would make such assumptions. I know some people do this because I've seen it here several times in the past and in other forums and newsgroups (I've even seen Steve Carlip make this claim and he's a GRist at UC Davis).

Stingray - So you're saying that you think some people introduce some concepts so that students will understand them when they see them etc? I can see that in the way some authors write, e.g. Physicists used to use this concept but now its old fashioned. In cases such as this its obvious that they don't use it. I'm referring to authors who use it heavily if not exclusively (e.g. in the rel-mass example Rindler uses it almost exclusively).

Do philosophers and historians "use" what they teach? Are all political science professors politicians? Nursing professors nurses? Do all business professors have a business?

I thought it was clear that I was speaking about research physicists who also write texts and/or teach the subject. If that was not clear then let it now be clear.

Teachers vary widely ... some 'simply' reuse what they themselves were taught (with a few minor tweaks as the years go by); others try to keep current, and will adapt and adopt as fads and understanding changes. Of course, if choice of 'textbooks' is not theirs to make, they will have to use the approaches of the materials they are required to teach to.

Thanks. However this is does not address the question of 'how do people arive at this conclusion of teaching but not doing' but addresses the question of 'why do authors do what they do.'

Pmb

 

[ZapperZ]

Which are not dissimilar to false general assumptions about, say, the law and lawyers.

AM

What? You mean to tell me that lawyers are not of the same specie as alligators after all?

<ZapperZ runs and hides>

Zz.

P.S. I apologize to all alligators.

 

[pmb_phy]

Which are not dissimilar to false general assumptions about, say, the law and lawyers.

AM

I don't know a lot of lawyers but there are groups for which generalities are used but which don't hold in all cases. For example; Consider the statement Humans have two arms and two legs.. That can be taken as being true to a certain extent. But we know that not all people have two arms and two legs, yet we are won't to call them "human".

There's a whole can of worms right there!

Pmb

 

[jtbell]

Stingray - So you're saying that you think some people introduce some concepts so that students will understand them when they see them etc? I can see that in the way some authors write, e.g. Physicists used to use this concept but now its old fashioned. In cases such as this its obvious that they don't use it. I'm referring to authors who use it heavily if not exclusively (e.g. in the rel-mass example Rindler uses it almost exclusively).

I thought it was clear that I was speaking about research physicists who also write texts and/or teach the subject. If that was not clear then let it now be clear.

OK, so the question at hand, as I understand it, is: why would a research physicist write a textbook or teach a course that uses a concept [e.g. relativistic mass] that falls within his research area, that he does not use in his own work and that in fact he does not believe to be a valid or useful concept?

I don't know. I've used and seen textbooks that include relativistic mass, but I don't know if their authors actively used relativity in their research work. And if I did, I wouldn't know their motivations anyway, never having asked them about it.

Morover, i doubt that anyone else here could know the answer to this question, unless he's in that category himself, or knows someone in that category and has discussed the subject with him.

I think the only way to answer your question is to identify someone who does what you're asking about, and then ask him about it directly, or find pertinent comments elsewhere in his writings. Anything else would be speculation or mind-reading.

 

[pmb_phy]

OK, so the question at hand, as I understand it, is: why would a research physicist write a textbook or teach a course that uses a concept [e.g. relativistic mass] that falls within his research area, that he does not use in his own work and that in fact he does not believe to be a valid or useful concept?

Its hard to phrase what I'm looking for. I've quite often seen people say things like "Some authors may write about such and such in their texts or Am. J. P. But researchers don't use it in their research etc." - I fail to understand their logic.

I don't know. I've used and seen textbooks that include relativistic mass, but I don't know if their authors actively used relativity in their research work. And if I did, I wouldn't know their motivations anyway, never having asked them about it.

I am unable to get to a library which has Phys. Rev. D etc so I'l have to wait to really see this (if that is even an accurate way to demonstrate that). I do see authors like Rindler use rel-mass in his texts and in his AJP articles. E.g.

A simple relativistic paradox about electrostatic energy, Wolfgang Rindler and Jack Denur, Am. J. Phys. 56(9), Sept. (1988).

I think the only way to answer your question is to identify someone who does what you're asking about, and then ask him about it directly, or find pertinent comments elsewhere in his writings. Anything else would be speculation or mind-reading.

I've tried that in all cases in the past and never got a straight answer except from Steve Carlip and yet I find his claim and explanation of it very hard to believe.

I wasn't certain that I'd be able to get an answer to my question by posting it here. But I knew as fact that I wouldn't if I didn't post it.

Pete

 

[ZapperZ]

Its hard to phrase what I'm looking for. I've quite often seen people say things like "Some authors may write about such and such in their texts or Am. J. P. But researchers don't use it in their research etc." - I fail to understand their logic.
I am unable to get to a library which has Phys. Rev. D etc so I'l have to wait to really see this (if that is even an accurate way to demonstrate that). I do see authors like Rindler use rel-mass in his texts and in his AJP articles. E.g.

Sorry, but this is getting extremely silly.

There is a clear difference between usage in research and usage in TEACHING. There are certain pedagogical reason why, when you teach, you need to present the material in a clear fashion to people who are clearly new to that subject matter. It is a complete waste of time to teach students as IF they know what it is already. Just because as a researcher I often use Torr as units of pressure doesn't mean I should confuse the students and use it in class. I still teach them using units of Pascal. Or just because I use "frequency" or "mass" in units of eV doesn't mean I should be teaching that in class!

Unless there is something more subversive behind this, this question has to be one of the most trivial issues I've read anywhere.

Zz.

 

[pmb_phy]

Sorry, but this is getting extremely silly.

There's not need to get all hot and bothered about it.

The question was very clear - Why do some people make the assumption that an author uses/teaches a concept and then people claim such authoirs (being researchers themselves) don't use that concept. Its nothing so trivial a thing such a a unit like "torr" but a concept held by some to be one of the most important implications of sr. The very topic I had in mind is a topic widely discussed in the literature so its nothing as trivial as you'd like it to believe.

If you find a question so silly then simply don't bother with it.

I have my answer so leave it at that. You really shouldn't sweat the small stuff. Life's far to short to worry about whether you think what someone else wants to know is trivial or not. Its only important if (1) the topic is physics and (2) its important to the person asking the question.

I suppose in retrospect this should have gone in another forum.

Let it rest zz

 

[Stingray]

Stingray - So you're saying that you think some people introduce some concepts so that students will understand them when they see them etc? I can see that in the way some authors write, e.g. Physicists used to use this concept but now its old fashioned. In cases such as this its obvious that they don't use it. I'm referring to authors who use it heavily if not exclusively (e.g. in the rel-mass example Rindler uses it almost exclusively).

I have never read any of Rindler's writing, so I can't really comment on him. I'm not that surprised, though. He is very old, and people tend to like to keep the styles that they learned with. I interact with quite a few (younger) relativists, and I can't recall any using relativistic mass. To be fair, though, I don't remember any of them teaching it either.

Anyways, it is not always so obvious when people are teaching concepts that they personally do not like. This is especially true in textbooks. Random disclaimers tend to find their way into lectures more easily. The only relativity text I can think of right now that is careful about what is conjecture and what isn't is Synge.

To answer your rephrased question, I think that there are some times where a physicist might teach a concept that he would not want to use in his research. This is especially true in introductory courses for the reasons I mentioned before.

 

[pmb_phy]

I have never read any of Rindler's writing, so I can't really comment on him. I'm not that surprised, though. He is very old, and people tend to like to keep the styles that they learned with. I interact with quite a few (younger) relativists, and I can't recall any using relativistic mass. To be fair, though, I don't remember any of them teaching it either.

I've never really seen a correlation between age and mass (other than gaining weight as we get older. ).

One example would be Peacock. He uses it in his text and he's rather young. He's a cosmologist

Thanks

Pete

 

[Stingray]

One example would be Peacock. He uses it in his text and he's rather young. He's a cosmologist

Ok, that's interesting. I have his book, but am on vacation right now, so I can't look it up.

 

[pmb_phy]

Ok, that's interesting. I have his book, but am on vacation right now, so I can't look it up.

You're in luck. That portion of his text is online at

http://assets.cambridge.org/0521422701/sample/0521422701WS.pdf

To answer your rephrased question, I think that there are some times where a physicist might teach a concept that he would not want to use in his research.

Would you do this and if so then why?

Thanks Stingray.

Pete

 

[Andrew Mason]

What? You mean to tell me that lawyers are not of the same specie as alligators after all?:

Not at all. Some lawyers are allegators and some are deallegators. An allegator advocates the matter and deallegator advocates the anti-matter. And judges, who are former allegators (or deallegators) think its all a croc.

AM

 

[pmb_phy]

Not at all. Some lawyers are allegators and some are deallegators. An allegator advocates the matter and deallegator advocates the anti-matter. And judges, who are former allegators (or deallegators) think its all a croc.

AM

Good one!

Pete

 

[pmb_phy]

Speaking of Steve Carlip - He claimed once that nobody uses (relativistic) mass in GR. Yet he published a paper in the American Journal of Physics on this point, i.e.

Kinetic Energy and the Equivalence Principle, Steve Carlip, Am.J.Phys. 65
(1998) 409-413

Online at - http://xxx.lanl.gov/PS_cache/gr-qc/pdf/9909/9909014.pdf
--------------------------------------
Abstract - According to the general theory of relativity, kinetic energy
contributes to gravitational mass. Surprisingly, the observational evidence
for this prediction does not seem to be discussed in the literature. I
reanalyze existing experimental data to test the equivalence principle for
the kinetic energy of atomic electrons, and show that fairly strong limits
on possible violations can be obtained. I discuss the relationship of this
result to the occasional claim that ``light falls with twice the
acceleration of ordinary matter.''
--------------------------------------

The contribution of gravitational mass is exactly what relativistic mass is all about!

Pete

 

[mahesh_2961]

hai,
my point is that the theories of Einstein theory that matter will shrink to zero size and will have infinite mass when traveling at the speed of light is something like saying "there are green faced men on moon who can sense our coming to moon and there by hide and we can never find them" .. My point is that such findings of Eienstien can never be experimentally proved ... The statement itself makes it impossible to prove ... This is my opinion and i apologize if i hurt any of u

regards
Mahesh

 

[ZapperZ]

hai,
my point is that the theories of Einstein theory that matter will shrink to zero size and will have infinite mass when traveling at the speed of light is something like saying "there are green faced men on moon who can sense our coming to moon and there by hide and we can never find them" .. My point is that such findings of Eienstien can never be experimentally proved ... The statement itself makes it impossible to prove ... This is my opinion and i apologize if i hurt any of u

regards
Mahesh

Then you obviously have no clue what the REST of his theory is saying. The fact that you DO get a relativistic mass is a clear experimental evidence. If you don't believe me, just visit any accelerator facility and see if they don't laugh right in your face when you tell them relativistic mass hasn't been observed experimentally. I work with 18 MeV electrons, and all of our beam diagnostics will give us nonsensical results if we neglect to consider the electron's relativistic mass.

The problem here is that you seem to only be focusing ONE result of this idea, being the situation where v=c. This is highly dubious since it isn't something that makes any sense. When a solution blows up like that, it means that physics cannot be used there! This applies not just in Special Relativity, but ALL of physics, and it does occur in all of physics! So if you are arguing that SR isn't "proven" because we can never detect the v=c situation because it goes to infinity, then you should also say ALL of physics isn't proven because in none of those cases can we "prove" the condition when the description goes infinite. This is absurd!

Empirical verification isn't just verifying a description at just ONE point. It is the verification of the description at several situations so that one not only obtains quantitative values, but also verify the TREND and qualitative description. You don't verify that Hooke's law is obeyed by a spring by measuring only one set of values for force and the corresponding extension. YOu measure a series of force vs. extension relationship and observe the corresponding trend. This has been done for practically ALL of the consequences of SR! We do not need to go to v=c cases to know that they work!

BTW, if SR doesn't work, your electronics will go bonkers. This is because many of the materials that are used in semiconductors that make up your processors have band structure calculations that had to include relativistic corrections. I also suggest you do not fly in a commercial airplane, since they ALL used GPS systems that incorporate SR/GR.

Zz.

P.S. Your "opinion" doesn't hurt me, it hurts you.

 

[pmb_phy]

The fact that you DO get a relativistic mass is a clear experimental evidence.

I must say, Zz, that I find that to be a very refreshing observation. Too bad more students don't learn this all too basic point.

Thank you!

Pete

 

[mahesh_2961]

Thank u for pointing out the flaws in my thinking ... in this case all were flaws
i understood my mistake

mahesh

 

[Stingray]

Would you do this and if so then why?

Yes, I think I would talk about subjects I wouldn't want to use myself. If I didn't have much time to cover a subject (but was forced to do it anyways), then I might go over certain concepts I didn't like just to get the students' interest, or to introduce something more quickly. It is very time consuming to describe everything with all the disclaimers one might want. It also tends to confuse people when you tell them things are "almost true."

In my limited teaching experience so far (as a TA only), I actually have made more of an effort to comment on the limitations of a particular concept than most do. This is the way I would've liked to have been taught, but I think it is very difficult to do it correctly. I usually just get a lot of blank stares. I suppose it's hard enough to understand one piece of material without being told a bunch of things about when it's really valid to use it.

 

[pmb_phy]

Yes, I think I would talk about subjects I wouldn't want to use myself. If I didn't have much time to cover a subject (but was forced to do it anyways), then I might go over certain concepts I didn't like just to get the students' interest, or to introduce something more quickly.

I think you missed the gist of the question. I'm not talking about a minor thing mentioned by an author. I'm talking about one of the more major themes in the entire text.

Thanks

Pete

 

[Stingray]

I think you missed the gist of the question. I'm not talking about a minor thing mentioned by an author. I'm talking about one of the more major themes in the entire text.

Then no, I wouldn't do that.

 

[pmb_phy]

Then no, I wouldn't do that.

A quick example comes to mind. In Schutz's new text Gravity from the Ground Up he has a section called Special Relativity: general consequences. He states that in that section he lists the most important consequences of the principle of relativity. If Schutz actually believes that all those items are the most important consequences of SR then one shouldn't expect him to ignore anyone of them in his own research.

At least in my opinion.

Thanks Stingray

Pete

 

[Stingray]

If Schutz actually believes that all those items are the most important consequences of SR then one shouldn't expect him to ignore anyone of them in his own research.

Yes, you're right. Unless he's talking from a purely historical perspective, which would probably be obvious from the context. Is that part of the book online?

 

[pmb_phy]

Yes, you're right. Unless he's talking from a purely historical perspective, which would probably be obvious from the context. Is that part of the book online?

No. I have the the book.

Pete

 

[pmb_phy]

Then you obviously have no clue what the REST of his theory is saying. The fact that you DO get a relativistic mass is a clear experimental evidence. If you don't believe me, just visit any accelerator facility and see if they don't laugh right in your face when you tell them relativistic mass hasn't been observed experimentally.

Speaking of which

Apparatus to measure relativistic mass increase, John W. Luetzelschwab, Am. J. Phys. 71 (9), September 2003
http://physics.dickinson.edu/~dept_web/activities/papers/relativity.pdf

An apparatus that uses readily available material to measure the relativistic mass increase of beta particles from a radioactive ²⁰⁴Tl source is described. Although the most accurate analysis uses curve fitting or a Kurie plot, students may just use the raw data and a simple calculation to verify the relativistic mass increase.

Pete