The speed of light; another perspective.

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StarstruckKid
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Re: The speed of light; another perspective.

Post by StarstruckKid » Tue Aug 17, 2010 2:40 am

Henning Makholm wrote:...Or transact all our business in natural units.
That is what I was aiming at. Most of us are caught up in definitions of elemental quantities in tems of completely relative units. Throwing all that out, as was attempted with the Hz unit, clears the air of misconceptions such as a 'light year' being somehow bound to the length of a planet's orbit, or the speed of light being being somehow tied to our derived units like the second. Even the choice of a cesium clock for a time standard is arbitrary, and the resulting definition is still some huge number that adds up to a second, for pete's sake.

In terms of defining units of measurement, there would seem to be a good argument for using one of the emission lines of hydrogen (the most basic element) for a unit of frequency/time (a 'hydro-tick'), and its associated wavelength (an 'angst') for the basis of a unit of length. Thus completely stepping away from ancient and human-based things like the second. I will drive my car at 90 nano-cs for a distance of (i'm not going to try to calculate this one) some-number-of giga-angsts, and get there in some-other-number-of giga-hydro-ticks.

Now we can communicate with those Bftsplkians.
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Markus Schwarz
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Re: The speed of light; another perspective.

Post by Markus Schwarz » Thu Aug 19, 2010 10:57 am

StarstruckKid wrote: In terms of defining units of measurement, there would seem to be a good argument for using one of the emission lines of hydrogen (the most basic element) for a unit of frequency/time
Replace hydrogen with cesium and you have the SI definition of a second, which is defined as the 9 192 631 770th multiple of the period of a certain emission line of cesium. I am no experimentalist, but the choice of cesium over hydrogen is most likely due to the fact that it is easier to archive the required precision. Since the speed of light in vacuum is defined to be 299 792 458 meters per second you have that one meter is the distance traveled by in the 299 792 458th part of a second. While the actual numbers might seem ridiculous, they are based on well-defined standards that can be reproduced everywhere.

So, sending the aliens these definitions, they will be able to reproduce our SI units and derive the conversion factors to their units. Most likely they will have a similar modern definition for a frbzzle which they could send us, so we would be able to reproduce their units. The only problem is our kilogram, which is defined as the mass of the kilogram prototype in Paris...

Besides, I think it would be interesting to the Bftsplkians to know our "human-based" units, because it would give them an idea about our everyday environment (The human size is about one meter.). And since our SI system is based on standards that can be reproduced everywhere, I don't see a problem.

By the way: your suggestion was used on Voyager's Golden Record to give aliens the time scale to which all times on the plate are referring.

StarstruckKid
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Re: The speed of light; another perspective.

Post by StarstruckKid » Mon Aug 23, 2010 12:10 am

Here's where we're still stuck: the second, a completely earth-bound, human-based measurement. IMHO, if we sent the Bftsplkians instructions to build a cesium clock so they could use our measurement of a second, after they got through laughing raucously, they would call us a bunch of arrogant, self-centered children and tell us not to call back until we could talk to them like cosmic adults. We are mired in the League of Extraordinary Gentlemen's metric system and our own self-importance, and would be seen as such by any civilization with any degree of sophistication.

I've thought further about the topic in the last week, and I make this suggestion in all seriousness: recognize the metric system for the anachronism it is and toss it. I'm not the first person to have a glimmer of this, as witnessed by the attempts at universality on Voyager (which, after being poisoned by the first Star Trek movie, will always be known to me as Veeger).

All technologically advanced 'races' will, like us, recognize c as a universal unit of speed. Let's do as I suggested above and begin to express speeds accordingly, My speed of 90 nano-c's was calculated as approximately equivalent to 60 mph.

All technologically advanced civilizations will recognize the hydrogen atom as the most basic and thus a logical basis for a system of measurement. The mass of H is the unit of mass. The wavelength of Lyman-alpha is the unit of distance. The time required to go one Lyman-alpha length is the unit of time. The frequency of Lyman-alpha is the unit of frequency.

These measurements would be scaled to useful sizes, the comparison of which would allow us to share information about things like our own relative sizes.

Class exercise: derive the rest of the system.

Think you're done? Bet you used base 10 to scale everything. Nope, ten fingers, human-based. The most basic number is 2. Go back and redo. But I'll give you a break: those lines of 1's and 0's will be as long as your arm, so use a natural scaling like 2 ^2 ^2 ==> 16, conveniently close to the 10 we're used to, and a likely compromise in any advanced technological civilization.

Now we can talk to the Bftsplkians and be on their level. Scaled appropriately, of course. :)
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Chris Peterson
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Re: The speed of light; another perspective.

Post by Chris Peterson » Mon Aug 23, 2010 12:26 am

StarstruckKid wrote:Here's where we're still stuck: the second, a completely earth-bound, human-based measurement...
We choose units that are convenient for us. Although they need to have a connection to something physical that can be used as a reference, they are otherwise arbitrary. We choose our number system in the same way, and ten is a perfectly reasonable choice. If I were going to change it, I'd go to 16 rather than 2. But there is no more reason to change our number system than there is to change the meter, gram, or second.

If we're going to invest energy in this, far better to simply make sure everybody uses the same system. And I'm talking about right here on Earth. Any aliens we encounter sophisticated enough to care... won't care.
Chris

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Re: The speed of light; another perspective.

Post by Beyond » Mon Aug 23, 2010 11:59 am

StarstruckKid wrote:Here's where we're still stuck: the second, a completely earth-bound, human-based measurement. IMHO, if we sent the Bftsplkians instructions to build a cesium clock so they could use our measurement of a second, after they got through laughing raucously, they would call us a bunch of arrogant, self-centered children and tell us not to call back until we could talk to them like cosmic adults. We are mired in the League of Extraordinary Gentlemen's metric system and our own self-importance, and would be seen as such by any civilization with any degree of sophistication.

I've thought further about the topic in the last week, and I make this suggestion in all seriousness: recognize the metric system for the anachronism it is and toss it. I'm not the first person to have a glimmer of this, as witnessed by the attempts at universality on Voyager (which, after being poisoned by the first Star Trek movie, will always be known to me as Veeger).

All technologically advanced 'races' will, like us, recognize c as a universal unit of speed. Let's do as I suggested above and begin to express speeds accordingly, My speed of 90 nano-c's was calculated as approximately equivalent to 60 mph.

All technologically advanced civilizations will recognize the hydrogen atom as the most basic and thus a logical basis for a system of measurement. The mass of H is the unit of mass. The wavelength of Lyman-alpha is the unit of distance. The time required to go one Lyman-alpha length is the unit of time. The frequency of Lyman-alpha is the unit of frequency.

These measurements would be scaled to useful sizes, the comparison of which would allow us to share information about things like our own relative sizes.

Class exercise: derive the rest of the system.

Think you're done? Bet you used base 10 to scale everything. Nope, ten fingers, human-based. The most basic number is 2. Go back and redo. But I'll give you a break: those lines of 1's and 0's will be as long as your arm, so use a natural scaling like 2 ^2 ^2 ==> 16, conveniently close to the 10 we're used to, and a likely compromise in any advanced technological civilization.

Now we can talk to the Bftsplkians and be on their level. Scaled appropriately, of course. :)
On my hands i have ten digits--eight fingers and two thumbs. So i would very much like to see at least a picture of those humans with ten fingers.
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