On 04/29/2007 04:34 AM, carmelo@pacific.net.sg argued in favor
of “relativistic mass”, citing various famous people who
recommended it, and concluding by saying:
The majority is still using “relativistic mass”!
Wow. That really puts things into perspective. Comparatively
speaking, that's the best argument for a speed-dependent mass
I've ever seen ... but in absolute terms, it is a travesty of
science. It reminds of of beer commercials that rely on
celebrity endorsements and peer pressure.
While we're on the subject: Some polls report that in the
US, a majority believes in ESP while a minority believes
in Darwinian evolution. Does that mean we should remodel
the curriculum to conform to the majority view? I don't
recommend it.
I also find it amusing just how often people who rely on
celebrity endorsements use such "data" selectively. It's
true that 45 years ago Feynman and his colleagues were
teaching the idea of speed-dependent mass ... but 35
years ago they weren't. What are we to make of that?
I take it as evidence that Feynman & Co. were capable
of changing their minds, capable of learning.
It often turns out that the first idea to come along
is not the best idea.
There are sound pedagogical and practical reasons for
preferring the spacetime approach, including simplicity,
power, elegance, and consistency. For details on what
I mean by that, see http://www.av8n.com/physics/odometer.pdf
Terminology and definitions are to a limited degree
arbitrary, but not to an unlimited degree. It is
certainly possible to find perverse terminology and
inconsistent definitions.
This isn't just about invariant mass. It is about the
whole spacetime "package", which includes invariant mass,
invariant length, invariant time, vectors including
4-vectors, rotations including boosts, and most of all,
the idea that relativity is /not/ a bunch of paradoxes.
Spacetime is simple -- about as simple as it could
possibly be, short of being identical to Euclidean
space.