Parsec

[sojourner]

Guys, you missed my point. Until aliens show up and we start hearing about what units of measure they use, all units of measure we know of are inherently earth based. We came up with them. We named them. We use them. We are from earth.

 

[CorporalCaptain]

I'm unaware of any physical unit that hasn't been officially defined in terms of physical processes that currently accepted theories believe to be constant.

 

[JRoss]

Well, chauvinism in favor of humans is justified, in my opinion. Seeing as none of these other species actually exist, nobody should get their panties in a twist over insensitivity to Vulcans. Besides, humans are special.

 

[Christopher]

I'm unaware of any physical unit that hasn't been officially defined in terms of physical processes that currently accepted theories believe to be constant.

The kilogram is still legally defined as the mass of a metal cylinder stored at the International Bureau of Weights and Measures in France. There's a campaign underway to redefine it based on a more fundamental physical property, because that cylinder's mass has actually changed a bit through erosion and thus the current definition is not precise enough for scientific purposes.

And even if the current legal definitions of most units are based on fundamental physical properties, the actual numbers they use are left over from the original Earth-centric definitions, since the redefinitions haven't actually changed the size of the units, just what they're defined in reference to. For instance, the meter is defined as the distance light travels in vacuum in 1/299792458 of a second. Why that particular fraction? Because it preserves the old definition of a meter that was based on the length of a metal rod stored in the same place as the kilogram, which was in turn based on an erroneous calculation of the circumference of the Earth. And why is the second defined as "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom?" Because that's the number of periods it takes to add up to 1/86400 of an Earth rotation.

So the fundamental units are indeed very Earth-centric in their magnitudes. The definitions haven't been changed to remove the terrestrial bias, merely to remove sources of error, to base them legally in something more permanent and unchanging than a hunk of metal in a room somewhere in France.

 

[CorporalCaptain]

I'm unaware of any physical unit that hasn't been officially defined in terms of physical processes that currently accepted theories believe to be constant.

The kilogram is still legally defined as the mass of a metal cylinder stored at the International Bureau of Weights and Measures in France. There's a campaign underway to redefine it based on a more fundamental physical property, because that cylinder's mass has actually changed a bit through erosion and thus the current definition is not precise enough for scientific purposes.

And even if the current legal definitions of most units are based on fundamental physical properties, the actual numbers they use are left over from the original Earth-centric definitions, since the redefinitions haven't actually changed the size of the units, just what they're defined in reference to. For instance, the meter is defined as the distance light travels in vacuum in 1/299792458 of a second. Why that particular fraction? Because it preserves the old definition of a meter that was based on the length of a metal rod stored in the same place as the kilogram, which was in turn based on an erroneous calculation of the circumference of the Earth. And why is the second defined as "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom?" Because that's the number of periods it takes to add up to 1/86400 of an Earth rotation.

So the fundamental units are indeed very Earth-centric in their magnitudes. The definitions haven't been changed to remove the terrestrial bias, merely to remove sources of error, to base them legally in something more permanent and unchanging than a hunk of metal in a room somewhere in France.

Thanks for brining the kilogram situation to my attention. It looks like action won't be taken at least until 2014.

As far as the numeric values of the fractions used, so what? If the physical units are based on physical processes that are believed to be constant, then it makes no difference how many times we count these processes to make up a unit. We can convert effortlessly to any aliens' units, as long as they are based on the same processes. The most important aspect of the units is that they posses objective definition.

 

[Hofner]

I have a simple solution to the standard kilogram problem. Define a kilogram as always being 1/80th of my weight. In other words, 'I' will always weigh 80 kg.

Now if you'll excuse me I just finished lunch. I need to dig up about a pound of cookies and a gallon of ice cream to tide me over 'til dinner in an hour.

Robert

 

[Nerys Myk]

Two pages and no Kessel Run jokes????

 

[sojourner]

^we usually do the Kessel Run joke at 12 pages.

 

[Asbo Zaprudder]

Kessel Run jokes? Over my dead Wookie.

 

[Skellington]

^we usually do the Kessel Run joke at 12 pages.

A page is a unit of distance, not time.

Also, most people think it takes 18.

 

[Newton]

Damn, you all beat me to the Kessel Run jokes.

I'd hoped I would be the first after reading the first page and a half.

 

[zar]

We can convert effortlessly to any aliens' units, as long as they are based on the same processes. The most important aspect of the units is that they posses objective definition.

Which the universal translator presumably does whenever a human says "parsec". I'm surprised no one has mentioned the UT in this thread yet.

 

[Asbo Zaprudder]

The Planck units are probably the closest thing to universal units of measurement as they are defined in terms of c, G, and ħ - http://en.wikipedia.org/wiki/Planck_units. Unfortunately, only the Planck mass lies anything near the realm of physical experience with which we are familiar at 2.176 51(13) × 10−8 kg (about the mass of a flea's egg, it's claimed).