[Phys-l] IGTPAOATPDNCWIPI

[John Denker <jsd@av8n.com>]

On 01/04/2011 09:08 AM, Scott Hill wrote:
> And I am certainly not going to
> get into a discussion of gauge invariance with my freshman classes!

At this point I would like to invoke the principle that ideas are
more important than terminology.

I don't much care whether anybody uses the term "gauge invariance".

Instead let's talk about the principle of IGTPAOATPDNCWIPI.  That
is short for "I get to pick an origin and the physics does not care
where I put it."

Examples of IGTPAOATPDNCWIPI include
 -- position
 -- velocity
 -- classical potential energy
 -- voltage (which is in some sense a corollary of the previous item)
 -- et cetera

I would be willing to bet that the principle of IGTPAOATPDNCWIPI is
covered in almost every freshman physics class.  It is super-useful,
reasonably simple, and reasonably intuitive.

  There are some very advanced things you can do with IGTPAOATPDNCWIPI,
  but that's not what I'm talking about here.  I'm just talking about
  the basic idea.

You may not see IGTPAOATPDNCWIPI in the syllabus or in the index of
the textbook, not in so many words, and I cannot explain why not ...
but OTOH you know the /idea/ is covered, and that's what is important.

Sometimes one encounters a synonym for IGTPAOATPDNCWIPI.  I believe it
is called "gauge invariance".