I was thinking today if all units of measure were lost and all means of measuring things were lost how could I start a new precise system of measure using natural things as a starting point.
Besides just creating a random size object and something to measure it with and then arbitrarily calling it something like 1" the only thing I can think of is to drill a tiny hole in an object of known thickness. Bring the object to sea level, maintain a known level of pure water above the hole and time the drops comming through the hole. This hole size would then become the standard for all linear measurements. This might not even work but is all I can come up with.
Can anyone come up with anything in nature that could be used as a standard?
How about using a thumb, say from the tip to the first knuckle. We could call that an inch. For longer measurements, the tip of the nose to the end of the fingers would be handy. We could call that a yard.
If we had lost all means of measuring, I think that this would be accurate enough.
Yeah, you’re use of “known” has no meaning, because you don’t know these things. You don’t know the thickness, you don’t know when you’re at sea level, you don’t know you have pure water, and you don’t know the time span. Now you can measure all that, but each measurement has it’s own errors associated with it that all combine into the uncertainty of the measurement of your hole.
The best standards are those that convert from something we can measure very accurately (time) to some other unit (length, voltage, etc.).
The depth of the water and the thickness of the plate with a hole drilled into it would start off as arbitrary. After the unit of measure was established they would have a known value.
You could, but it wouldn’t be a very good standard relative to what we’ve had even over a hundred years ago.
Water depth would change depending on your altitude and temperature (among other things), and you wouldn’t have anyway to measure those environemtal parameters. Over time, the depth of your water would change due to evaporation. Even the thickness of the plate would vary with temperature and would eventually decay over time, just like the world’s kg standard.
The topic was not so much about my example as much as it was about others examples of what they might use a standard. My example was more of a random thought for the sake of an example.
But just dealing with your reply, I did stipulate sea level, I thought about temp but would alos have to look for something in nature that would relfect temp.
All of the standard units of measurement (except the kilogram, but they’re working on that) already HAVE been tied to nature. The second is defined as the time it takes for a cesium atom to vibrate a certain number of times. The meter is defined relative to the wavelength of a specific photon. Etc, etc.
Smeghead, are these measurements considered so precise because by our standards we are not able to measure it own variations? Or is it just very precise by any standards?
If I were trying to find a replacement for the standard meter, I’d find something that forms a cubic crystal and use that to define a length. Looking in Wikipedia, it appears that iron pyrite naturally appears in cubic form, so I’d find as perfect a sample of that and use that as the standard. (I think NaCl also makes a cube, but it’s affected by moisture, so I think the pyrite would be better.)
Just came in to say this, too and was ninja’ed. But since i did my wiki-research, i’ll post anyway.
But we already have natural standards;
Metre: Since 1983, it has been defined as “the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second.”[wikiP]
Kilogram: The gram was originally defined in 1795 as the mass of one cubic centimeter of water at 4 °C, making the kilogram equal to the mass of one liter of water. [wikiP]
Second: The duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. In 1997, the CIPM affirmed that the preceding definition “refers to a caesium atom at rest at a temperature of 0 K.”[WikiP]
I understand that it might be difficult to reproduce these measurements in your kitchen or garage, however.
That quoted reference of the kilogram sounds “natural” enough to me.
I can’t believe we’ve gone this far and no one has mentioned the Plank units.
They’re basically horrible for everyday use being either way too small or way too big, but they do define natural units and would serve the purpose of being definable without actual physical objects like an official meter stick.
Once I’ve identified the standard, other lengths can be measured from this one. There is precedent for this. In Paris, there is the international prototype kilogram, a cylinder made of a platinum alloy. For a long time, its mass defined the kilogram. The OP supposes a world in which “all units of measure were lost and all means of measuring things were lost” so in that case, I think it’s reason to arbitrarily select an object as the standard.