for how long has it been the duration that it is now?... how lng has the second ben in existence?... what ancient societies used the second?... how long has the second even existed?
As I understand it, it's a proto-babylonian second-of arc (as in the time it takes for the sun to travel an arc-second of earth). I just packed all my F$%&ing text books on astronomy or else I could dig it up for you. I can even evision the page with sidebar graphic with a little stick-figure Ptolemy...
Through the haze of memory I recall a precendece for circles being divided into units of 60 due to the babylonians base 60 counting system. This was applied to early work in dividing circles into "gons" made up of chords defined as (well, maybe not THEN) 1/21600 of a circle, or 60 per degree.
As an aside: It took us 360 days to complete a year cycle (or so they thought) so, you divide a circle or eliptic into 360 units. This is the basis for our "Geometrical degees": 360 for a full circle.
No, not at all. Many of the SI standards are set according to the constants of physics - i.e. based on some real, observable phenomenon (like the coulomb). If I think of an everday example I'll follow up on it.
Actually, the answer is yes. The reason that the answer is yes is that, (for eample in the case of the meter) the measure was first decided upon, and then a naturally accuring standard found to match it. In the case of the meter, they chose (originally) one ten-millionth of the length of the earth's meridian along a quadrant (which is one fourth the circumference of the earth).
Later: The 1889 definition of the meter, based upon the artifact international prototype of platinum-iridium, was replaced by the CGPM in 1960 using a definition based upon a wavelength of krypton-86 radiation. This definition was adopted in order to reduce the uncertainty with which the meter may be realized. In turn, to further reduce the uncertainty, in 1983 the CGPM replaced this latter definition by the following definition:
The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.
http://physics.nist.gov/cuu/Units/meter.html
These are all arbitrary ways of describing an arbitrary measure chosen by man.
Steve, Start poking aroud that site for the the various "quantized" units, particularly those applied to the measurement of electodynamics, magnetism, and light, and you will find that they are derived from very unarbitrary origins. For example, the unit "Photon". Feynman had a great section on this in Six Not So Easy Pieces (I think) about how you would give an alien civilization directeions to our planet , define left and right, and ensure they were not made of antimatter all in one transmission.
Although, now that I think about fstrblly's post more philosophically, I suppose picking anything as a basis with which to measure or quantify anything is arbitrary. Even if the Angstrom is based on the classic mechanical size of a hydrogen atom, who the hell picked that as the basis for anything?
I seem to remember a book about Newton (James Gleick's bio, I think it was) describing measuring things in seconds as "esoteric" in the 16th century. That led me to believe that it was an impractically small measure of time that no one had taken seriously until that point.
that's what I meant. Deep thoughts, deep thoughts! On a side note, I really do prefer talking about things other than riding around in circles. Who knew the off season could be so enlightening, what with talk of corrugated fences and time measurements, et al...?
You've hit on my point: Simply because the choice of a unit of measure occurs in nature does not make it's selection as a unit of measure any less arbitrary.
Pythagorean Triples are a good illustration - http://www.mcs.surrey.ac.uk/Personal/R.Knott/Pythag/pythag.html#trigen
They work with any unit of measure (for length) as long as you use them same units consitently. Could be meters, feet, cubits, or width of a hydrogen atom - doesn't matter. Stack 3 on one side, 4 on another, then set the ends 5 apart, and you've built a perfect right angle - which is how the Egyptians laid out their pyramids... only they used cubits.
I often use "cubit", "furlong", or "fortnight" when I feel the need for an esoteric unit. Like citing that "band x" is better than Manudo.
Anyway, I took your first argument to mean that there were no units of measurement that existed that did not in some way refer back to something indemic to earth. Sorry.
There are alot of amazingly complex fractals that can be generated from applying generations of unitless ratios like Pythagrean's... aw, you kow what? This is too much.
Let's go back to talking about poop and stuff, I do enough of this thinking crap at work.
What if all this, everything - us, the earth, the solar system, this Greatful Dead bootleg - EVERYTHING was really just sub-atomic particles on, like, god's thumbnail, man....
16 comments:
As I understand it, it's a proto-babylonian second-of arc (as in the time it takes for the sun to travel an arc-second of earth).
I just packed all my F$%&ing text books on astronomy or else I could dig it up for you. I can even evision the page with sidebar graphic with a little stick-figure Ptolemy...
does it have some cosmic importance or is it arbitrary?.. i am having a hard time googling this...
i wonder if other societies utilized teh second...
it seems thought that ancient peoples would have no need of measuring time in such small units...
i am reading a lot of intersting things in researching this...
Through the haze of memory I recall a precendece for circles being divided into units of 60 due to the babylonians base 60 counting system.
This was applied to early work in dividing circles into "gons" made up of chords defined as (well, maybe not THEN) 1/21600 of a circle, or 60 per degree.
As an aside:
It took us 360 days to complete a year cycle (or so they thought)
so, you divide a circle or eliptic into 360 units. This is the basis for our "Geometrical degees": 360 for a full circle.
This is exactly the kind of question Cecil Adams answers in his column, The Straight Dope. He has a website, www.straightdope.com.
I searched the archives for something about this and found this: www.straightdope.com/classics/a1_125.html
-Corey
isn't any unit of measurement arbitrary to a certain degree?
Fstrblly,
No, not at all. Many of the SI standards are set according to the constants of physics - i.e. based on some real, observable phenomenon (like the coulomb).
If I think of an everday example I'll follow up on it.
parke,
Actually, the answer is yes. The reason that the answer is yes is that, (for eample in the case of the meter) the measure was first decided upon, and then a naturally accuring standard found to match it. In the case of the meter, they chose (originally) one ten-millionth of the length of the earth's meridian along a quadrant (which is one fourth the circumference of the earth).
Later:
The 1889 definition of the meter, based upon the artifact international prototype of platinum-iridium, was replaced by the CGPM in 1960 using a definition based upon a wavelength of krypton-86 radiation. This definition was adopted in order to reduce the uncertainty with which the meter may be realized. In turn, to further reduce the uncertainty, in 1983 the CGPM replaced this latter definition by the following definition:
The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.
http://physics.nist.gov/cuu/Units/meter.html
These are all arbitrary ways of describing an arbitrary measure chosen by man.
Steve,
Start poking aroud that site for the the various "quantized" units, particularly those applied to the measurement of electodynamics, magnetism, and light, and you will find that they are derived from very unarbitrary origins. For example, the unit "Photon".
Feynman had a great section on this in Six Not So Easy Pieces (I think) about how you would give an alien civilization directeions to our planet , define left and right, and ensure they were not made of antimatter all in one transmission.
Although, now that I think about fstrblly's post more philosophically, I suppose picking anything as a basis with which to measure or quantify anything is arbitrary.
Even if the Angstrom is based on the classic mechanical size of a hydrogen atom, who the hell picked that as the basis for anything?
I seem to remember a book about Newton (James Gleick's bio, I think it was) describing measuring things in seconds as "esoteric" in the 16th century. That led me to believe that it was an impractically small measure of time that no one had taken seriously until that point.
This is a fascinating conversation.
that's what I meant. Deep thoughts, deep thoughts! On a side note, I really do prefer talking about things other than riding around in circles. Who knew the off season could be so enlightening, what with talk of corrugated fences and time measurements, et al...?
Parke,
You've hit on my point: Simply because the choice of a unit of measure occurs in nature does not make it's selection as a unit of measure any less arbitrary.
Pythagorean Triples are a good illustration - http://www.mcs.surrey.ac.uk/Personal/R.Knott/Pythag/pythag.html#trigen
They work with any unit of measure (for length) as long as you use them same units consitently. Could be meters, feet, cubits, or width of a hydrogen atom - doesn't matter. Stack 3 on one side, 4 on another, then set the ends 5 apart, and you've built a perfect right angle - which is how the Egyptians laid out their pyramids... only they used cubits.
Cubit is 12 palm widths, right?
I often use "cubit", "furlong", or "fortnight" when I feel the need for an esoteric unit. Like citing that "band x" is better than Manudo.
Anyway, I took your first argument to mean that there were no units of measurement that existed that did not in some way refer back to something indemic to earth. Sorry.
There are alot of amazingly complex fractals that can be generated from applying generations of unitless ratios like Pythagrean's... aw, you kow what? This is too much.
Let's go back to talking about poop and stuff, I do enough of this thinking crap at work.
take it home steve...
One last one:
What if all this, everything - us, the earth, the solar system, this Greatful Dead bootleg - EVERYTHING was really just sub-atomic particles on, like, god's thumbnail, man....
Cubit = length pf Pharoh's arm from elbow knob to tip of Pharoh's extended middle finger...
And get your minds out of the gutter.
Later redefined by Vitruvius as six palm widths of the hand (but then, only as a ratio to other body part sizes).
Again, get your minds out of the gutter.
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