

Exhaustive, commented, list of units - btilly
http://futureboy.us/frinkdata/units.txt

======
btilly
Check it out if for no other reason than to read the rant about how poorly
defined the candela is.

~~~
DrJokepu
Also, it's really hard to resist the temptation to "rant back" on the kilogram
question. Unfortunately / fortunately, HN comments are not the right place for
that.

(Basically, _kg_ is the perfect unit of mass and if you disagree you are a
heathen and should be burned)

~~~
btilly
His complaint is that if kg is the perfect unit of mass then make what we call
the kg be the base unit and call that a gram instead. Makes perfect sense to
me.

Of course this is an imperfect world. In a perfect world I'd like a meter
chosen so that gravity is, to a good approximation, 1 m/s at sea level, and
I'd like all of the units to be in base 12. (Easy divisibility by 3 is often
very useful.) Including time, so that one doesn't have the awkward 3.6 factor
converting from m/s to km/h. And our number system should also be base 12,
and...I think you can see that I'm willing to complain about lots of things
which will never change.

~~~
eru
I want my number system to be in base 11 or some other prime number. You see:
The vast majority of numbers are never going to evenly divide our base, no
matter what base we choose. So we might as well go for a solution that
minimizes the special cases.

~~~
btilly
The vast majority of the time that people wish to divide something evenly,
they want to divide it by a small number.

~~~
eru
Yes. I just wanted to give the standard mathematician's tongue-in-cheek reply
to proposals like base 12.

To be earnest, octal is quite a nice base. Or -2 (minus two!). Or 10, but with
digits from -5 to +5, though that representation should be redundant, I guess.

To speak of redundant representations: Fibonacci numbering is also interesting
(<http://en.wikipedia.org/wiki/Fibonacci_coding>). Or skew binary numbers.

------
asmithmd1
It is missing hardness units: <http://en.wikipedia.org/wiki/Shore_durometer>
<http://en.wikipedia.org/wiki/Brinell_hardness>

Also roofers commonly refer to a square of
shingles:[http://wiki.answers.com/Q/How_many_square_feet_will_a_square...](http://wiki.answers.com/Q/How_many_square_feet_will_a_square_of_shingles_cover)

------
bluesmoon
what? no Helens

    
    
        beauty =!= H
        Helen := H      // The beauty required to launch a 1000 ships
                        // A mH is the beauty required to launch 1 ship

~~~
philwelch
Wouldn't that be a mH (milli-Helen)? A micro-Helen would only launch 1/1,000th
of a ship, so perhaps a kayak or life raft.

~~~
bluesmoon
yep, my mistake, will fix

------
aston
Seems to be missing

    
    
      hella ::- 1ee27    // Northern California slang for "lots of" or "very"
    

[http://www.popsci.com/science/article/2010-03/physics-
studen...](http://www.popsci.com/science/article/2010-03/physics-student-
petitions-hella-si-units)

------
jarin
It's not a complete list of units without the hella- prefix.

~~~
tome
hellacandela?

------
DougWebb
It's missing the megalithic yard and related units. <http://www.ancient-
wisdom.co.uk/megalithicyard.htm>

This turns out to be a really cool system of measurement involving distance,
volume, mass, frequency, etc, all based ultimately on the rotation of the
earth.

Edit: the book Urial's Machine and its successors expand a great deal on this
system of measurement, and how there are echos of it in Old English and
Babylonian measurement systems. I can't find an online description, though.

------
redcap
energy := c^2 // convert mass to energy

Looks like it's missing some mass.

~~~
sesqu
There's also a comment in Kelvin regarding how the triple point of water is
defined to be at 0.01 °C, not 0 °C, that reads a little confused. I wonder why
it's defined like that, anyway.

The bit is used for information because information is almost defined as the
expected length of an optimally (context-free) coded word, using a base 2
code. Some physicists prefer base _e_ , in which case it's measured in _nat_
s.

~~~
bluesmoon
the triple point of water is defined as 0.01 °C in order for a difference of 1
°C to be equal to a difference of 1 K.

To put it another way, the triple point of water is known to be 273.16 K, and
the boiling point 373.15 K. Now if this mapped on to 0 °C and 100 °C, then
we'd be left with a situation where 100 kelvins would be equivalent to 100.01
Celsius degrees. Instead, by defining the triple point of water as 0.01 °C
(still 273.16 K), we now get an interval of 100 kelvins being equal to an
interval of 100 Celsius degrees.

This is also why the term centigrade is no longer used... it's no longer 100
even.

~~~
eru
By the way, they should re-rig the definition of the Kelvin, to make Boltzmann
1. (The Planck units already do this.)

We would probably need either very tiny or very large multiplies of this new
Kelvin for anything practical, though. (Depending on your choice for the other
units. The The Planck unit of temperature is way too big for practical uses
for example.)

------
zck
There's also the _units_ command:
<http://www.gnu.org/software/units/units.html>

~~~
ggbaker
This file is actually /usr/share/misc/units.dat from units.

------
nandemo
Tangentially related, large named numbers in Japanese:

<http://en.wikipedia.org/wiki/Japanese_numerals#Large_numbers>

無量大数=muryōtaisū=10^88.

------
roofone
I'm impressed it has the smoot and evens includes a reference:
[http://spectrum.lbl.gov/www/personnel/smoot/smoot-
measure.ht...](http://spectrum.lbl.gov/www/personnel/smoot/smoot-
measure.html).

------
RiderOfGiraffes
It's missing the hundred, an old English measure of area.

~~~
gjm11
It defines "hundred" = 100, and likewise for other spelled-out numbers. I
don't think it has any way of making it mean 100 in one context and an area
(of, AIUI, indeterminate size) in another.

------
kristiandupont
Does anybody know why the standard unit for mass is _kilo_ grams?

~~~
dfox
THis comes from practical and historical considerations. Mass is probably most
commonly used quantity by non-technical people, so it is desirable to maintain
continuity with previous systems which had gram as base unit. On the other
hand kilogram as base unit makes many useful relations between various
quantities simpler not to mention that it is significantly more practical to
make and maintain prototype of kilogram, than prototype of gram.

------
CERTIORARI
It's missing Lovelace (Ll), the standard unit of suckiness.

<http://www.infonet.ee/~sbernard/asr/computer.html>

