[e2e] evolution of bandwidth as a term
cannara at attglobal.net
Thu Oct 2 20:48:26 PDT 2003
"Semantic drift", "metaphor"... Sounds like the good old '70s and the
insurgence of PC thinking. When your Dr. discovers a malignant tumor in your
belly, you'll thank more than God for practical medical science's adherence to
strict meanings of technical terms.
On "stifling metaphor and economy of expression" -- "bandwidth" is longer than
"bitrate". What's economical about using the longer, incorrect term? What's
economical about requiring the reader to take mental time out to decide which
meaning of the word you intend? What's expressive about causing an educated
reader to sense from your misuse of an important term that the rest of what
you say may be bogus?
"Language is inherently ambiguous" is a straw man, and we all know that.
Ambiguity delays, even prevents communication, which is exactly opposite of
humankind's purpose in inventing communication forms. Misusing a term for no
good scientific reason is ignorant or manipulative -- if the former,
forgivable and correctable; if the latter, inexcusable and simply bad manners,
especially to those new to the language or discipline.
I'm certain ISI teaches networking better than to lead students to believe:
"For a fixed protocol and transmission system, the two are usually directly
related, and therefore straightforward to interchange." We have "usually" in
the sentence, for what purpose? Perhaps to cover the raw fact that unforeseen
symbol choices at the transmission level easily make it false? Perhaps
because the bandwidths of the relevant inter-layer communication paths have
little to do with interlayer bitrates? Perhaps the student is actually never
told what Nyquist and Shannon meant, or what Baudot did? The sentence you
supply shows precisely the damage to scientific discussion that misuse of just
the term "bandwidth" can bring to a table of discourse.
Ted Faber wrote:
> On Thu, Oct 02, 2003 at 05:34:09PM -0400, John Day wrote:
> > At 12:32 -0700 10/2/03, Loki Jorgenson wrote:
> > > [Evoloution (!?) deleted]
> > >Agreed?
> > NO!
> > The Internet nor much else of the modern world could not have been
> > built without carefully defining and adhering to the definitions of
> > such things as: bandwidth, mass, joule, kilogram, power, charge,
> > bit, watt, etc. Getting terms right and sticking to them is crucial
> > for all scientific pursuits, if not intellectual pursuits. Although,
> > I am aware that certain "disciplines" have made much in the last few
> > years about ignoring such things. But as far as I am concerned they
> > can all go Fish!
> I understand and empathize with your desire for clarity of thought and
> expression. I further agree that because signal processing and
> networking are closely related disciplines, one must frequently
> draw a careful distinction between the bandwidth of a signal and the
> data rate of a system sending information using that signal.
> However, let's not be dogmatic to the point of stifling metaphor and
> economy of expression, both of which are essential for understanding.
> Let me make three points:
> 1) While the language of science is far and away more precise than that
> of laymen or soft disciplines, claiming that it is without ambiguity is
> disengenuous. For example, an ounce can refer to voulme or weight; a
> tonne and a ton are different; the square root of negative one is j to
> engineers and i to mathematicians; and even how much a billion is can
> depend on the nationality of the speaker. Certainly all these can be
> resolved by careful specification, but so can signal bandwidth and
> information bandwidth.
> 2) Other scientific endeavors have seen similar semantic drift when an
> apt metaphor helped understanding or as a field was beginning to
> understand new things. Ocean currents and electrical currents are very
> different things, but no one objects to using the same word to name and
> different units to measure them. That's probably untrue - the good
> folks who lay underwater power cable probably have to express their
> measures carefully. Similar extentions have given us Hamming distance,
> relativistic mass, and gene splices.
> 3) The particular metaphor under fire - information rate as bandwidth -
> is an enlightenting description in several circumstances and the two are
> often directly related. For a fixed protocol and transmission system,
> the two are usually directly related, and therefore straightforward to
> interchange. As a result, one naturally uses whichever representation
> is easiest. One can wind up with "10 lb.s of mass" kinds of
> misstatements, but in a broad range of circumstances, there's no harm in
> interchanging the quantities. Done properly, capacity planning this way
> can even enhance the understanding of the planners; knowing that every
> 300Hz is a phone call worth a certain amount of money can make tradeoffs
> clear. I wouldn't be surprised to see some bandwith allocation problems
> calculated in dollars. Why stifle that when no clarity is lost?
> To restate, I think people should strive for clairity in their
> expression, but it's also important to recognize that language is
> inherently ambiguous, especially when ideas are in flux.
> Ted Faber
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