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Ghost Post
Icarian Member

 Posted: Tue Dec 07, 1999 5:47 am    Post subject: 1 I think I may have a possible solution. The contents seem to be everything one needs to reproduce some of the SI standard units from the current definitions. A laser - determination of the meter: a meter is the distance light travels in a vacuum in 1/299,792,458 second. For this you will also need a precise clock to measure time. A small metal cylinder composed of a platinum-iridium alloy - the international standard of the kilogram in Paris A container of water - could also give you a kilogram since 1000 cubic centimeters of water at standard temperature have a mass of 1 kg. Wait, you have no thermometer! Maybe this is how one derives the temperature standard! A small black box with a steady blinking light. A chemical analysis of the box indicates it contains titanium, copper, various complex hydrocarbons, silicon, and a cesium isotope. - This is a precise atomic clock necessary for determination of the second, and therefore, also the meter. A large collection of thin metal sheets inscribed with symbols and drawings, apparently referring to the other items. - This describes how to use everything to determine the standard units. Maybe it also describes the radian and steradian measures of plane and solid angles, respectively. There seems to be no device for deriving either the coulomb or the ampere. Maybe if you take apart the atomic clock you can set up an apparatus to determine these. There is also no way of deriving the lumen or the candela. Maybe you could rig up something with the laser. [This message has been edited by Derkage (edited 12-07-1999).]
Ghost Post
Icarian Member

 Posted: Tue Dec 07, 1999 6:20 am    Post subject: 2 Here are the official definitions of the SI base units of measurements: length: meter (m) ". . . the length of the path traveled by light in vacuum in 1/299,792,458 of a second." (1983) mass: kilogram (kg) ". . . this prototype [a certain platinum-iridium cylinder] shall henceforth be considered to be the unit of mass." (1889) time: second (s) ". . . the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine leves of the ground state of the cesium-133 atom." (1967) electric current: ampere (A) ". . . that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed 1 meter apart in a vacuum, would produce between these conductors a force equal to 2 x 10^-7 newton per meter of length." (1946) thermodynamic temperature: kelvin (K) ". . . the fraction 1/273.16 of the thermodynamic temperature of the triple point of water." (1967) amount of substance: mole (mol) ". . . the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon-12." (1971) luminous intensity: candela (cd) ". . . the luminous intensity, in the perpendicular direction, of a surface of 1/600,000 square meter of a blackbody at the temperature of freezing platinum under a pressure of 101.325 newtons per square meter." (1967) [A newton (N) is a kg-m/s^2] (This is reprinted from my physics text, which was adapted from "The International System of Units," National Bureau of Standards Special Publication 330, 1972 edition. The definitions above were adopted by the General Conference of Weights and Measures, an international body, on the dates shown.)
daniel801
Daedalian Member

 Posted: Fri Dec 10, 1999 4:46 pm    Post subject: 3 well, after reading all of that, i will refrain from posting my guess of it being a battery.
walkupjd
Guest

 Posted: Sun Dec 12, 1999 4:20 am    Post subject: 4 I spotted platinum-iridium and cesium right away and knew it was a collection of standards. The copper and titanium confused me so I did a search and found that thermocouples make of copper and titanium and niobium are used to make a very stable and precise voltage source. Look for Josephson junctions. There is also an interesting factoid about an old standard of the yard (I think) that the Brits had. It was found to be growing! Probably due to crystalline changes in the bronze rod. A fascinating odyssey of research.
Ghost Post
Icarian Member

 Posted: Thu Dec 16, 1999 5:10 pm    Post subject: 5 Thanks to those who posted previous notes on this puzzle - I got quite a reminder, and quite an education, from some of that material. I think this puzzle also requires a shift in perspective, so to speak: you'd have to figure that aliens would try to make their message simple, and, moreover, uniform. What then, is the defining feature of the craft? I would suggest it is the EM pulse that alerts us of its presence. Further, the craft is powered by "magnetic sails" - both of these hints lead me to believe that magnetism is involved in the solution. Since we were alerted to the ship's presence by its electromagnetic signals, I'd think the aliens would look to build upon this common knowledge. The properties of the metals in the ship may have certain magnetic properties - and here I'd need some assistance. One further and probably unrelated note: a laser, shone through water, would create a spectrum...for what purpose, I don't know. I look forward to any responses.
Ghost Post
Icarian Member

 Posted: Sun Dec 19, 1999 5:43 am    Post subject: 6 will have a go at the SI units derkage described: i dont believe the laser is for the meter, anyone who found the pod knows the speed of light, to measure the metre you only need a unit of time, identified by the cesium clock kilogram with the cylinder second with the cesium clock heres an idea for the ampere: placing two of the metal sheets exacly 1 meter apart (meter already determined), connect them somehow, (perhaps with another sheet), then shine the laser on one of them. this will produce a photoelectric effect and the current can then be measured water used to identify the kelvin, its triple point water could also contain exactly 1 mole the strength of the laser could be used to determine the candela, or even the blinking light on the clock
Ghost Post
Icarian Member

 Posted: Sun Dec 19, 1999 5:46 am    Post subject: 7 it just occured to me as i submitted that the units derkage gave can not be the base SI units, meter makes second redundand,they are not independant units so cant be base.
Ghost Post
Icarian Member

 Posted: Mon Dec 20, 1999 8:04 pm    Post subject: 8 Though I'm sure the solutions above are right, what would be the point of communicating SI units to an alien race? It seems like a waste of a spacecraft full of, uh, stuff...
Ghost Post
Icarian Member

 Posted: Tue Dec 21, 1999 5:18 am    Post subject: 9 have just read minotaurs result, i stand by my claim that the laser is useless as a distance indicator, speed of light is constant throughout the universe, and the laser is a waste of space
Tony
Icarian Member

 Posted: Wed Dec 29, 1999 6:26 pm    Post subject: 10 Not to sound nitpicky, but the answer to the alien artifacts puzzle mentioned that a "kelvin degree is . . . " I believe (I may be wrong) that when one refers to the kelvin temperature scale, divisions are NOT said to be called "degrees" but rather simply as "kelvin." For example, one would be technically incorrect in stating a temperature as "240 degrees Kelvin" or "240 Kelvin degrees." Rather, the correct terminology should be "this substance is measured at a temperature of 240 Kelvin." I believe "degrees" are reserved for the C and F temperature scales. Very interesting puzzle nonetheless. -Tony
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