OT: Speed of light [was Re: Why not a Python compiler?]

[Dotan Cohen]

On 12/02/2008, Erik Max Francis <max at alcyone.com> wrote:
> Dennis Lee Bieber wrote:
>
>  > On Tue, 12 Feb 2008 00:18:38 -0800, Erik Max Francis <max at alcyone.com>
>  > declaimed the following in comp.lang.python:
>  >
>  >> equivalence for everyday usage and make no requirement of using the
>  >> "proper" units for mass (kg) vs. weight (N) for, say, buying things at
>  >
>  >       Ah, but in the US, the unwashed masses (as in "lots of people")
>  > don't even know that there is a difference between lb-force and lb-mass
>  > (okay, all they know of is a simple "lb" which is based upon force of
>  > gravity at point of measurement, while lb-mass is a sort of artificial
>  > unit... don't mention slugs <G>)
>
>
> Yes, exactly; you started with another word game and then in the process
>  dismissed it with a half-joke at the end.  Pounds came first, and
>  rationalized systems (lbm/lbf, slug/lb, and even ridiculous retrofits
>  like kg/kgf, completely turning the apple cart upside down) came
>  afterwards.  The point is, the difference between the two is _totally
>  irrelevant_ to those "unwashed masses" (and in the contexts we've been
>  talking about).  Even NIST (among other) SI guidelines acknowledge that
>  because, well, it's blatantly obvious.
>
>  That actually feeds right back into my earlier port about physics
>  subsuming terminology to its own ends.  Making the distinction between
>  mass and weight is critical for understanding physics, but not for
>  everyday behavior involving measuring things in pounds; after all, in
>  extending the popular concept of a "pound," different physicists made a
>  distinction between mass and weight differently (i.e., the rationalized
>  systems above) such that there is no accepted standard.  Of _course_
>  physicists have to make a distinction between mass and weight, and to do
>  so with Imperial or American systems of units requires deciding which
>  one a "pound" is, and what to do with the other unit.  But that's a
>  physicist making distinctions that do not exist in the more general
>  language, just the same as a physicist meaning something different by
>  "free fall" than a layman.
>
>  But (say) dinging some Joe Schmo because he doesn't know that a pound is
>  really a unit of force (or mass) is really just playing pointless word
>  games.  As I said earlier, there are better ways to teach physics.

I recently had to tell my mother how to convert kilograms to pounds. I
told her that near the Earth's surface, she should multiply by 2.2.
Knowing me, she didn't even bother to ask about the "near the Earth's
surface" part. We've already established that that's where she and all
her friends live in other conversations.

Note that Google will give a calculator result for "1 kilogram in
pounds", but not for "1 kilogram in inches". I wonder why not? After
all, both are conversions of incompatible measurements, ie, they
measure different things.


Dotan Cohen

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A: Because it messes up the order in which people normally read text.
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