Re: hands-on gauge transformations

[John Denker <jsd@MONMOUTH.COM>]

At 01:05 PM 7/30/00 -0500, Jack Uretsky wrote:
> Hi all-
>         Interesting thought:  Changing the "zero" from which potential
> is measured is like a gauge transformation.

Yup, it's always nice to have a connection between
  -- feet on the ground: moving the black lead of the voltmeter
     from one node to another, and
  -- head in the clouds:  gauge transformations.

But...  why be so tentative?
  -- Why say it "is like" a gauge transformation
     rather than "is" a gauge transformation?
  -- Is there a definition of gauge transformation under which
     phi -> phi + const is not a full-fledged member?

(Of course nobody is suggesting this is the only gauge transformation).