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Science Forum Index » Physics - Research Forum » Data types in physics
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| David Golden |
 Posted: Fri Apr 25, 2008 4:43 pm |
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John Forkosh wrote:
Quote: pioneer1 <1pioneer1@gmail.com> wrote:
I know this is not how physicists see it. I am looking to find the
correct mathematical terminology so that I can state the problem
clearly. Do you know a field of physics or math that studies these
things?
I believe you may be barking up the wrong "tree" (sorry).
I'm not aware of a field of physics that studies these things,
per se, but I believe dimensional analysis is what you're
looking for. In other words, what you call data types
is what physics calls units.
FWIW, a far-from-exhaustive grab-bag:
*** "Frink" [1] and "Fortress" [2] are examples of science ior
engineering oriented programming language projects where dimensions and
units are intended to be supported as built in dynamic (frink) or
static (fortress) language features.
The Fortress language specification has quite a lot of formalism -
the "1.0 Beta" specification (at [2]) chapters 18, 29 and 35 are a good
attempt to explore rigorous support for statically checked physical
dimensions and units in a practical programming language (re "1.0
Beta": note that the "1.0" specification (temporarily) dropped
dimensions and units, the particular topic of interest here!)
In the 1.0 Beta spec, dimensions are described as "type-like constructs"
and units as "constructs that modify types and values" (page 155),
though those statements should really be read in context of the spec.
*** The "Qi" [3] programming language has a powerful/meta type system
using sequent notation. In Qi, the programmer should be able to
construct types that allow static checking of dimensions and units, as
(nearly) shown by [3] (the specifics of [3]'s system may not be
entirely satisfactory compared to [2]'s, but it's still a nice example)
*** "Q" [4] is an example of a programming language using an equational
paradigm. Not _directly_ to do with physical dimensions and units in
programming, but reading its documentation should help a lot when
thinking about what the symbol "=" can actually mean in different
contexts in computing, since in most programming languages it's quite
the false friend for mathematicians...
[1] http://futureboy.us/frinkdocs/#HowFrinkIsDifferent
[2]
http://projectfortress.sun.com/Projects/Community/wiki/FortressDocumentation
[3] http://www.lambdassociates.org/studies/study11.htm
[4] http://q-lang.sourceforge.net/examples/ |
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| Bossavit |
| Posted: Sat Apr 26, 2008 5:57 pm |
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Pioneer1:
Quote: Thanks for the references. Unfortunately, except for the first one I
couldn't find them online. Do you know if they exist online?
The American Journal of Physics is indeed online, the whole collection.
But one must be a subscriber to the paper version to get electronic
access (with a small additional fee).
Another reference, germane to some turns the discussion has taken after
your first query:
J.M. Levy-Leblond: "On the Conceptual Nature of the Physical
Constants", Rivista del Nuovo Cimento, 7, 2 (1977), pp. 187-214. |
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| pioneer1 |
| Posted: Mon Apr 28, 2008 7:22 am |
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On Apr 14, 5:35 pm, hel...@astro.multiCLOTHESvax.de (Phillip Helbig---
remove CLOTHES to reply) wrote:
Quote: In other words, the quantity of interest (F in the examples above) is
proportional to various things we can measure (like r, or m). In
general, to make the proportionality an equality, we need a constant.
Do I understand correctly that you are saying that F itself is not a
measurable quantity? We measure other quantities such as r (radius of
orbit) and m (mass of satellite) and then infer the value of F. I am
not sure we can measure these quantities observationally to obtain
force. Force and radius are never together in formulas used to compute
orbits because force is written down temporarily and always cancels.
The same is true for m since that too cancels out of the formulas to
compute orbits. We can only calculate force from given values not from
observations. If r is given then, from F=GM/r2 we can compute F. But
since that computed value of F refers to force in F=ma and since m
cancels, our calculation amounts to computing acceleration. We then
call acceleration force. This suggests to me that orbits are
independent of force. |
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