Adamantium93 said:
On a related note, I also have no idea why we use Fahrenheit over Celsius. Freezing=0ºC and boiling=100ºC (for water). That is so easy. Why would you choose to say freezing=32ºF and boiling=212ºF instead? Again, the problem is primarily that I know what 80ºF feels like because that's the measurement system everyone around me uses, but I have to go look it up to know that that's the equivalent of ~27ºC.
you like many assume that they CHOSE 32ºF as the freezing point of water
they didn't
they chose 0ºF as the freezing point of SEA water
at 0ºF a sea captain had to start worrying about ice forming on his ship's hull and icebergs in the water
talideon said:
drthmik said:
"The metre is the length of the path travelled by light in vacuum during a time interval of 1 / 299,792,458 of a second."
... Wait that's not divisible by 10
And since meters were developed by the french after the french revolution you can't say that the meter is BASED on the speed of light
http://en.wikipedia.org/wiki/History_of_the_metre
http://en.wikipedia.org/wiki/Speed_of_light
and light travels 1 foot in 1 nanosecond
That's only a rough approximation to use as a rule of thumb though.
drthmik said:
so what?
You carve up the distance light travels into a certain number of chunks
We cave it up into a different number of chunks
that is the definition of arbitrary
Eh... it's less arbitrary than that. In fact, the definition of the metre has always been an attempt to find a non-arbitrary measurement based off of natural constants.
The
real original proposal for the metre came from John Wilkins in the mid-1600s, and was defined as the length of a pendulum with a half-period of one second. The only truly arbitrary thing (at the time) there is the length of a second. However, it was found that due to gravity varying slightly over the surface of the Earth, that wasn't ultimately workable, so
after the French Revolution, it was defined as 1/10,000,000th the distance from the North Pole to the Equator along the meridian line passing through Paris. This was pretty damned close to Wilkins' original proposal and had the benefit of being more absolute. However, we later found that measurement to be less stable and more mathematically complex than would be convenient, so other standards were used, until we settled on using the speed of light, which is, best as we can tell, a fundamental constant.
And thus it turns out that the only thing that makes a metre arbitrary is the length of a second, and I'm OK with that.
ar·bi·trar·y
ˈärbiˌtrerē/
adjective
adjective: arbitrary
1.
based on random choice or personal whim, rather than any reason or system.
Why the length of a pendulum swing?
Answer: Some guy in the 1600s thought it would be a good length
Why 1/10,000,000th the distance from the North Pole to the Equator along the meridian line passing through Paris?
why not London or New York?
Why not the circumference of the earth at the 22nd parallel? Or at the equator?
Why not 1/100,000,000th or 1/50,000,000?
Answer: Some guy though it would be a good length
Why the length of the path travelled by light in vacuum during a time interval of 1 / 299,792,458 of a second?
Why not 1/300,000,000 of a second?
or even 1/299,792,450 of a second?
WHY!?!
W H Y ! ? !
I'll tell you why
Some
guy
thought
it
would
be
a
good
length
And a lot of other people agreed
if they had not the meter would have vanished having never seen the light of day
You would say that he (and they) had good reasons to do it the way they did
well guess what
some guy thought a foot would be a good length
his reason was that there were too many different lengths and it was too ARBITRARY so he standardized it so that when one person said foot everyone knew what he meant
it helped trade
and map making
and Law
and construction
and many other things
Standardized Measurements are not universal truths no matter how you come up with them
they are practical language and culture
they exist to service understanding
and changing them all for no better reason than a bunch of guys in lab coats(who use the other system ANYWAY) find it EASIER is not a reason to confuse the language of a people for decades