Re: [Phys-L] The Make-Believe World of Real-World Physics

[John Denker <jsd@av8n.com>]

Imagine hiring a metal-working machinist to fabricate a complicated
part.  Would you rather have a machinist with skill but no tools, 
or tools but no skill?

I consider that to be a silly question.  The machinist needs both
skill and tools to get the job done.


On 07/11/2013 11:34 AM, Anthony Lapinski wrote:
> Imagine teaching a physics class with mostly concepts and little/no math.
> Now imagine teaching a physics class with mostly math and few
> concepts/demos. I wonder how students would react to these. What would
> they like more? What would they look forward to more? What would they
> share with their family at home?

Please please don't formulate the question that way.  Just because 
option (a) is no good does *not* prove that option (b) is any good.
Manichean multiple-guess reasoning rots the brain.

Physics requires both concepts /and/ formalism (including math).
It covers an area in the plane, with concepts along one axis and 
formalism along the other axis.  If you fixate on one axis or the 
other, you cover zero percent of the area.

You need the physics in order to motivate the math, and you need
the math in order to explain the physics.  At this point I do the
itsy-bitsy-spider thing with my hands.
  http://www.youtube.com/watch?v=eiWbjoOOly4&t=0m55s

> I like the Hewitt approach (and his books have little/no math)

Parts of that book are carefully thought out, but many other parts 
are just pathetic.  Mostly it emphasizes rote regurgitation to the
near exclusion of reasoning.

The overall result is to present something that is completely useless.
I don't know what it is, but it's not physics.

Physics concepts are simple.  Because they are so simple, they are
useless unless they can be /combined/ with other concepts, combined
into long /chains/ of reasoning.  Hewitt fails to do this.

For example:  In section 38.4 it emphasizes that «Light behaves like 
waves when it travels in empty space, and like particles when it interacts
with solid matter.» 
   A few sentences later we find «CONCEPT CHECK: What causes light to 
   behave like a wave? Like a particle?»

I’m sorry, but that is not a check of the concept. That is only a check
for rote regurgitation of the words that appear higher up the page. If 
you wanted to check the concept, you would ask the student to apply the 
concept in some setting different from the original setting.

The fact that Hewitt is completely wrong about the distinction between
waves and particles just rubs salt into the wound.  This, by the way,
is one of the eleventeen things that makes rote learning dangerous:
Rote can be used to learn wrong things just as easily as right things.

I used to think that "Conceptual Physics" was a euphemism for "Bonehead
Physics" but even that is too generous.  Whatever it is, it's not physics.

http://www.av8n.com/physics/hewitt.htm