[DWJ] Units of distance and speed
Belben, Philip (Energy Wholesale)
Philip.Belben at eon-uk.com
Fri Dec 8 05:04:38 EST 2006
A discussion like this puts me straight into geek mode, for which I make
almost no apology.
>>>>> When an author tells me that the heroine's spaceship is eleventy-
>>>>> billion kilometres from the other spaceship, I tend to snarl, "why
>>>>> can't you use light-years, you stupid bugger?", and to decide that
>>>>> the stupid bugger probably thinks a light-year is a unit of time.
We get all sorts of units for distances in space. The two most commonly
used by astronomers, AU and parsecs, seem to be the least commonly used
by SF writers. I think it was Jack Chalker who gave so many distances
of planets from stars in millions of km that I started pencilling in the
figures in AU...
> One of my friends has "The speed of light is 1,802,617,500,000
> furlongs per fortnight" as a .sig, and I never had the heart to try to
> find out whether he's right or not. I don't mean by experiment, I
> mean by asking someone to do the arithmetic for me!
Furlongs per fortnight, eh? That's about a sixth of a millimetre per
second, isn't it.
The speed of light is 1,802,617,499,785 and a quarter, based on the
international definitions of feet, yards and things. The US definition,
just to confuse everyone, gives 1,802,613,894,550 and a quarter, so the
last few digits aren't very useful.
Tape recording seems to generate strange units. Most reels of tape have
lengths that are a multiple of 600 feet, so I tend to quote them in
stadia (and get funny looks)
On the other hand, tape speeds are generally given in inches per second,
and this is almost the same as attoparsecs per microfortnight. (I tend
to normalise this to picoparsecs per fortnight, but this is frowned on,
for some reason)
Finally, a very useful figure in some fields: the speed of light is just
under 1 foot per nanosecond.
ObDWJ: can't think of anything really relevant, but what are the units
of measurement along the Ayewards-Naywards axis?
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