by StarstruckKid » Mon Aug 16, 2010 2:18 am
I think what wonderboy was getting at was the difficulty of communicating with the inhabitants of another world how each side measures fundamental quantities like the speed of light (c). Not only are inertial frames of reference all local, so are systems of measurement.
Suppose we managed to establish radio contact with the inhabitants of Bftsplk and we want to talk about the speed of light. Here on Earth we measure it in distances based on things like the diameter of the planet (the meter) or the length of the King's royal pedal extremities (the foot) extended to how many times the King can put one foot in front of the other before he gets tired (5280, a mile). Our time measurements are based on the rotational speed of the Earth and the apparent size of the Sun (and Moon). Since the angular size of the Sun is about 1/2 degree, it takes almost exactly 2 minutes to pass a given fixed reference point.
But on Bftsplk, the unit of length is based on the size of the average Bftsplkian's facial tentacle (very democratic beings, those Bftsplkians) or a frbzzle, and their unit of time is based on how long it takes the average Bftsplkian to fall a distance of 1717 (did I mention they have 17 tentacles?) frbzzles, or a hhrrrrckkk. Also did I mention they are about the size of a terrestrial palmetto bug? They have determined that the speed of light is 98-13/17 vrsook (I won't attempt to explain their numeric system) frbzzles per hhrrrrckkk.
To make matters worse, our planets have a large differential velocity, so the Doppler effect prevents using the frequency of the radio wave as a reference.
BUT, we can get away from local units of measure, and dispense with defining c in those terms by turning the problem upside down. Start with the fundamental constant, c, and work backwards. Much as we dispensed with the old cycles per second yardstick with frequency and now call one cycle per second a Hertz (not a fundamental quantity, however, it's still based on the second).
So then we measure how long it takes our radio signal to go to Bftsplk and back,(they'd have to have a repeater pointed back at us), we tell them it was x seconds, they tell us it was y hhrrrrckkks, and voila! we now know how many seconds per hhrrrrckkk.
Now we just need to rework our road signs. I will no longer be driving 60 miles per hour, it will be, oh, about 90 nano-c's, if I've figured right.
Michael
I think what wonderboy was getting at was the difficulty of communicating with the inhabitants of another world how each side measures fundamental quantities like the speed of light ([i]c[/i]). Not only are inertial frames of reference all local, so are systems of measurement.
Suppose we managed to establish radio contact with the inhabitants of Bftsplk and we want to talk about the speed of light. Here on Earth we measure it in distances based on things like the diameter of the planet (the meter) or the length of the King's royal pedal extremities (the foot) extended to how many times the King can put one foot in front of the other before he gets tired (5280, a mile). Our time measurements are based on the rotational speed of the Earth and the apparent size of the Sun (and Moon). Since the angular size of the Sun is about 1/2 degree, it takes almost exactly 2 minutes to pass a given fixed reference point.
But on Bftsplk, the unit of length is based on the size of the average Bftsplkian's facial tentacle (very democratic beings, those Bftsplkians) or a [i]frbzzle[/i], and their unit of time is based on how long it takes the average Bftsplkian to fall a distance of 1717 (did I mention they have 17 tentacles?) [i]frbzzles[/i], or a [i]hhrrrrckkk[/i]. Also did I mention they are about the size of a terrestrial palmetto bug? They have determined that the speed of light is 98-13/17 [i]vrsook[/i] (I won't attempt to explain their numeric system) [i]frbzzles[/i] per [i]hhrrrrckkk[/i].
To make matters worse, our planets have a large differential velocity, so the Doppler effect prevents using the frequency of the radio wave as a reference.
BUT, we can get away from local units of measure, and dispense with defining [i]c[/i] in those terms by turning the problem upside down. Start with the fundamental constant, [i]c[/i], and work backwards. Much as we dispensed with the old cycles per second yardstick with frequency and now call one cycle per second a Hertz (not a fundamental quantity, however, it's still based on the second).
So then we measure how long it takes our radio signal to go to Bftsplk and back,(they'd have to have a repeater pointed back at us), we tell them it was [b]x[/b] seconds, they tell us it was [b]y[/b] [i]hhrrrrckkks[/i], and voila! we now know how many seconds per [i]hhrrrrckkk[/i].
Now we just need to rework our road signs. I will no longer be driving 60 miles per hour, it will be, oh, about 90 nano-[i]c[/i]'s, if I've figured right.
Michael