Re: [Phys-l] What comes first, the equation or the explanation?

[John Denker <jsd@av8n.com>]

On 12/22/2011 10:02 AM, Paul Nord wrote:
> Picking up on something Brian Jones said at the summer AAPT meeting,
> I'll say that experience comes first.  He described how students,
> allowed to play with florescent sheets and various colored LED's gain
> understanding from that experience.  When asked specific question
> about light and energy later they have a sense that blue light has
> more "something" than red light.

I say that (a) sometimes experience comes first, and (b) sometimes 
it doesn't.  Anecdotes of type "a" don't disprove "b".

It's an iterative process.  Chickens and eggs.  I know this is 
true in my own work, and I'm not alone.

There are entire books devoted to the topic of figuring out what
a given equation means.  Almost any book on differential equations
falls into this category.  As a specific physics-related example,
40 years ago Kip Thorne said of general relativity: "We have the
equations.  We've had the equations for 60 years.  We think the
equations are right.  We can solve them in special cases, but we
don't know how to solve them in general."

To this day Kip is still busy wringing physics out of those
equations.  He /explicitly/ describes it as an iterative
process:  calculations lead to physical insight, which guides 
further calculations, and so on, iteratively.

He gave the colloquium at Berkeley last month. The video is 
available for free on the web:
  http://physics.berkeley.edu/events/Colloquia/movies/col.streaming.11-14-11.mov

If you are at all interested in how physics is done, you should
pay attention to how this guy does it.  He's seriously good at
it.  He's also seriously good at explaining it.  He also has
what you might call style, or class, or panache.  We should
remember that science is not just utilitarian, it is also an
art form unto itself.