Why should we depart from conventional physics teaching?

[maverick280857]

Hi

There are some physicists who argue that teaching classical physics (particularly classical mechanics) at the pre/undergraduate level (as in schools in some countries) is not favorable because by the time students take up advanced courses on relativity, reimannian geometry, etc. it becomes difficult for them to visualize space-time distortions as proposed by Einstein and others, since they have been so involved with Euclidian ideas. They would prefer to teach ideas about space-time, gravity waves, curved space and why classical physics is inadequate, right in school so that students are given enough time to think about the transition to modern ideas, which can be difficult.

On the other hand, there are physicists, teachers and perhaps even students who would like to continue with the time-tested way of physics teaching, that which starts with classical physics--mechanics, motion, dynamics, waves and oscillations, rotation, electricity and magnetism, electromagnetic theory and finally modern physics with some quantum physics.

My questions pertain primarily to today's world, in particular, the domain of physics: why, if at all, should we depart from the conventional pattern of teaching physics and mathematics to orient students to understand physics from the grassroot level? Is the current school course (as mentioned in the paragraph above) course inadequate? Is it completely in phase with the requirements of current academics?

Finally, what are your views on improving problem solving abilities of students in physics?

Cheers
Vivek

 

[Brad_Ad23]

When I started learning physics on my own I started off with modern physics and then went to classical physics. It seems more natural and I have a much easier time understanding the modern day principles and the like. So I'd be inclined to agree that we should change the way we teach physics.

 

[quartodeciman]

So much today seems like a general switching from teaching physics to teaching advanced mathematics techniques. This is probably due to heavy emphasis on current theoretical developments like supersymmetric strings and loops. It is a problem that preparation for these august subjects requires a lot more lead time than used to be required in the past. But physics is not just mathematics, and valuable lessons from the past are lost when everything is aimed at getting to current interests. I would hope students will get a good classical background early on. It would be valuable to supplement this with critical analysis of underlying assumptions that both guide future discoveries and cause classical physics to lag behind later knowledge. But I don't really have a solution to the time investment problem, so I suspect classical physics studies will continue to get abbreviated.

 

[JohnDubYa]

RE: "They would prefer to teach ideas about space-time, gravity waves, curved space and why classical physics is inadequate, right in school so that students are given enough time to think about the transition to modern ideas, which can be difficult."

Yeah, this sounds like a great idea, given that students usually enter their first introductory physics courses with a firm understanding of differential geometry.

 

[ZapperZ]

When I started learning physics on my own I started off with modern physics and then went to classical physics. It seems more natural and I have a much easier time understanding the modern day principles and the like. So I'd be inclined to agree that we should change the way we teach physics.

How did you reconcile the fact that there aren't a lot of clear demonstration of modern physics, whereas examples of classical physics are abundant and all around us? Without such demonstration, wouldn't it appear that you accepted something simply out of faith rather than clear observation?

Zz.

 

[JohnDubYa]

I would like to know how students are expected to understand angular momentum without any exposure to classical physics. Is it just a term they just memorize and accept? How in the Hell are students expected to write down the Schroedinger equation for systems when they don't even understand potential energy? (And how do you understand potential energy without understanding conservative and non-conservative forces?)

 

[maverick280857]

I would like to know how students are expected to understand angular momentum without any exposure to classical physics. Is it just a term they just memorize and accept? How in the Hell are students expected to write down the Schroedinger equation for systems when they don't even understand potential energy? (And how do you understand potential energy without understanding conservative and non-conservative forces?)

Well the purpose behind asking the (original) questions was to get views from different people at PF. But I would like to know what put these questions in your mind, JohnDubYa, in the context of the original questions asked.

Teaching new things or changing the course structure (in my opinion) implies making it better to understand and comprehend so that students end up visualizing and getting good physical picture of phenomena. Of course I do agree with you about possible haphazardness in classical physics teaching...it is quite incorrect to become exposed to Quantum Mechanics without knowing anything about energy and related classical physics concepts.

Another problem that students face (as I have too) is solving problems in physics. I remember reading the chapter again and getting involved in discussions to solve my problems and surely ended up with better concepts than I had when I first sat down to solve (unsuccessfully) the problem at hand. Yet, at other times, setting up the correct equations was a difficult job despite becoming sure that I had a reasonably good understanding of concepts.

No matter how interesting, easy or difficult physics courses are made and no matter how much effort students put into it, they will still end up with unsolved (mysterious/unreasonable looking) problems. Now somebody might argue that this is the beauty of science and logic, but we must find better ways of solving problems. Largely, "theory" and "problems" are like water-tight compartments and with different people and time constraints, one takes a back seat whereas actually, both are equally important.

Cheers
Vivek

 

[JohnDubYa]

RE: "Well the purpose behind asking the (original) questions was to get views from different people at PF. But I would like to know what put these questions in your mind, JohnDubYa, in the context of the original questions asked."

I think my questions are rather obvious. If you teach modern physics before classical physics, then how are students expected to understand the classical analogy for each physical property they encounter?

What do you tell a student who raises his hand and asks "What is potential energy?" without resorting to a lecture in classical physics?

I'm open to new ideas. In fact, I tend to rebel against the traditional way of teaching most of classical physics. But I don't like this idea at all. Classical physics for the vast majority of students is still the best topic for them to learn. And there is nothing incorrect about it at the macroscopic level, which is what concerns them anyway.

 

[robphy]

I feel physics curricula has to change if our society is to advance in our understanding of the physical world. Certainly, today's curricula isn't the same as it was 50 years ago, 100 years ago, etc...

I'd be curious to see how the college physics textbook has changed over the ages. I wonder when "the Maxwell Equations" was first put in an introductory textbook.

While it is certainly unrealistic to teach or require (say) differential geometry in an introductory physics course, it seems it shouldn't be too hard to plant the seeds for more advanced topics. For example, in an introductory course, I have asked students to measure the ratio between the circumference and the radius on a plane, on a basketball, and on some various areas around campus. This, of course, introduces a definition of pi on a plane and makes a point that geometry may be different and non-intuitive on non-planar surfaces. That's as far as I go on this point.

For another example, I am trying to get students to pay more attention to drawing and interpreting distance-vs-time-diagrams (a.k.a. spacetime diagrams [for Galilean Relativity]) instead of merely relying on kinematic equations. Indeed, relativity has taught us that the "geometry of spacetime" is an important concept... and here is one way to plant the seeds of that idea.

We can't do away with teaching classical physics because it is "the physics" that we have everyday experience with. We can, however, refine how we present and emphasize those ideas to ease the transition to more advanced ideas. More advanced theoretical physics, for example, seems to put more emphasis on energy and momentum rather than force. Maybe textbooks should move in that direction.

 

[JohnDubYa]

robphy has an interesting take. Maybe we should divide introductory physics into two parts: Forces and Energy. The first part would encompass both mechanics and E&M, but only discuss forces and motion. The second part would encompass both mechanics and E&M, but from an energy perspective.

Can it be done? I have thought about doing this in the past, but something fouled up the plan. I cannot remember what it was, unfortunately.

 

[robphy]

Here are some interesting approaches to introductory physics:

http://www.physics.pomona.edu/sixideas/
[Six Ideas That Shaped Physics, T.A. Moore]

http://www4.ncsu.edu/~rwchabay/mi/
[Matter & Interactions, Chabay and Sherwood]

http://departments.colgate.edu/physics/curricular/general.html
[Modern Introductory Physics, Holbrow et al]
reviews: http://www.physicstoday.org/pt/vol-54/iss-5/p63b.html

http://www.math.ups.edu/~martinj/calcphys/calcphys.html
[Integrated Physics and Calculus, Rex and Jackson]

web-based (I haven't looked at these carefully yet):

http://www.physics.nmt.edu/~raymond/classes/ph13xbook/node1.html
[A Radically Modern Approach to Introductory Physics, D.J. Raymond]

http://www.lightandmatter.com
[Light and Matter, Crowell]


As a postscript to my initial post...
I feel we need to introduce some "20th-century physics" into introductory physics. I'm not exactly sure how to do it yet. But I think we do have to [gradually] change the way we teach introductory physics.

 

[ZapperZ]

As a postscript to my initial post...
I feel we need to introduce some "20th-century physics" into introductory physics. I'm not exactly sure how to do it yet. But I think we do have to [gradually] change the way we teach introductory physics.

Unless they have changed the curriculum since the last time I took intro physics (which at this point seems to be during the last ice age), I thought Modern Physics IS already part of standard intro physics courses, at least for undergrads in US institutions.

Zz.

 

[robphy]

Unless they have changed the curriculum since the last time I took intro physics (which at this point seems to be during the last ice age), I thought Modern Physics IS already part of standard intro physics courses, at least for undergrads in US institutions.

Zz.

In my experience, for most students, "introductory physics" is a two-semester course: Mechanics (with possibly-though-unlikely Thermo, Fluids, or Waves) and Electromagnetism (with possibly-though-unlikely Optics). "Modern Physics" (e.g. relativity, quantum physics) is usually at the end of the textbook, which [I feel] is rarely gotten to in a two-semester sequence. In my experience, I had "Optics and Modern Physics" as my third course. Generally, such a course is only for physics or engineering majors.

Some of the new textbooks I listed above try to bring in some modern physics concepts early on.

The underlying motivation for my comments is this:
in the attempt to attract more physics majors, it might be good to give students a taste of what modern physicists are doing earlier rather than later in the sequence.

 

[JohnDubYa]

Thanks for the links. I was one of the reviewers of Thomas Moore's book. I have some reservations about devoting 1/6 of the entire introductory physics course to relativity, but omitting optics altogether.

Here's the usual, and tough, question: If we introduce more modern physics topics into introductory physics, what do we cut out?

In the algebra-based courses, I am pretty comfortable cutting out large chunks of the second semester. But the calculus-based courses are much tougher to modify if we keep in mind that engineering students need firm foundations in E&M to succeed academically.

 

[robphy]

Thanks for the links. I was one of the reviewers of Thomas Moore's book. I have some reservations about devoting 1/6 of the entire introductory physics course to relativity, but omitting optics altogether.

Moore comments on optics http://www.physics.pomona.edu/sixideas/sifaq.html#GeOpts
In addition, Moore is a relativist.
Note that 1/6 is on Quantum Mechanics, and another 1/6 is on Thermodynamics.

With Moore's recent interest in the Principle of Least Action
(which one could be considered a seventh idea), one might see Optics getting worked back in.

Here's the usual, and tough, question: If we introduce more modern physics topics into introductory physics, what do we cut out?

In the algebra-based courses, I am pretty comfortable cutting out large chunks of the second semester. But the calculus-based courses are much tougher to modify if we keep in mind that engineering students need firm foundations in E&M to succeed academically.

I'm not suggesting we necessarily cut something out. Instead, I suggest we carefully work in some aspects of modern physics. (How? Not sure yet.)

As you suggest, it seems appropriate that algebra-based (non-physics-major based) and calculus-based (physics/math-major based) courses place their emphasis differently.

 

[Brad_Ad23]

How did you reconcile the fact that there aren't a lot of clear demonstration of modern physics, whereas examples of classical physics are abundant and all around us? Without such demonstration, wouldn't it appear that you accepted something simply out of faith rather than clear observation?

Zz.

Instead of looking for demonstrations, I went and did research on the subjects (also taking into account direct technological processes that depend on quantum effects). Finding that a lot of the math involved confused me, I quickly taught myself calculus and it made more sense. Classical physics came easily.

I suppose it works for some people and not for others. I would recommend that perhaps instead we should stop having middle school science classes being a rehashing of elementary school sciences and jump into the standard 3 cources--bio,chem,phys, and then in high school there can be a myriad of different options. Of course this also requires us to then completely revamp the entire education system, especially in the maths area. But honestly, we desperately need said change.

 

[ZapperZ]

Instead of looking for demonstrations, I went and did research on the subjects (also taking into account direct technological processes that depend on quantum effects).

Pardon me for saying this, but this is exactly what I was asking. How do you reconcile that you can't see how QM works? QM, of all things, is very unintuitive. Did you accept the appearence of Schrodinger Equation out of nowhere? How did you know what a "momentum operator" is, if you haven't a clue what a "momentum" is from classical mechanics? What about the concept of "potential energy"?

The main advantage of classical mechanics is that we can demonstrate basic ideas easily. In fact, we can use the students' own personal experiences (which is made up of entirely classical events) and explain how physics are involved in them. This allows for physics to be something they can comprehend and understand, rather than simply stuff they read in a book and can't relate to. Simply just reading about QM and it's "technological processes" without exactly seeing where and how it works is exactly the kind of things we should avoid in good teaching.

Zz.

 

[maverick280857]

Unless they have changed the curriculum since the last time I took intro physics (which at this point seems to be during the last ice age), I thought Modern Physics IS already part of standard intro physics courses, at least for undergrads in US institutions.

Zz.

Fyi, in India, the average level of physics course in the last two years of school (called Class 11 and 12) includes a substantial amount of Newtonian mechanics, oscillations and waves, gravitation, fluid statics and dynamics, thermodynamics and heat transfer (and in the second year:) electrostatics, circuits, magnetism, electrodynamics, geometric and wave optics, interference, diffraction, polarization and finally modern physics (Bohr's Theory, Photoelectric Effect, etc.).

The topics taught in schools are not backed up with too much mathematics since all the mathematics we do at schools is total differential calculus and first integrals of the elementary kind. While students know what vectors are and have played around with them quite a bit, they do not know what vector calculus is and what div, grad, curl are.

Not that such a treatment is immediately needed, but when they go to college, it is assumed that they are well versed in physics to make a quick transition to vector calculus and apply it to the topics they have not used it with, such as central forces, electricity, Maxwell's Equations, etc. This transition is usually easy since it is purely mathematical in the beginning and the physical feel is imparted as one goes along.

I am not sure what the syllabus in US schools demands at this level, but one reason why the transition to the new physics is made difficult in India, in my opinion is due to this extreme channelization of the course. Effectively, this leaves a large number of students with a large number of half-baked ideas and unsolved problems through which they begin to fear physics and stray away from it. And these students need not necessarily be non-inclined towards physics.

 

[Brad_Ad23]

Pardon me for saying this, but this is exactly what I was asking. How do you reconcile that you can't see how QM works? QM, of all things, is very unintuitive. Did you accept the appearence of Schrodinger Equation out of nowhere? How did you know what a "momentum operator" is, if you haven't a clue what a "momentum" is from classical mechanics? What about the concept of "potential energy"?

The main advantage of classical mechanics is that we can demonstrate basic ideas easily. In fact, we can use the students' own personal experiences (which is made up of entirely classical events) and explain how physics are involved in them. This allows for physics to be something they can comprehend and understand, rather than simply stuff they read in a book and can't relate to. Simply just reading about QM and it's "technological processes" without exactly seeing where and how it works is exactly the kind of things we should avoid in good teaching.

Zz.

Ah, I see we have a misunderstanding of terminology here. My mistake entirely. What I learned first was the concepts behind quantum mechanics. The mathematical rigor and hence true comprehension I agree should be built up from classical physics.

 

[maverick280857]

Ah, I see we have a misunderstanding of terminology here. My mistake entirely. What I learned first was the concepts behind quantum mechanics. The mathematical rigor and hence true comprehension I agree should be built up from classical physics.

Yeah...perhaps then we tend to appreciate it more since we know why and where the "old" physics is inadequate and we try to fill gaps.