Units of Measurement

Cthulhu.Science

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Kurt Vonnegut, Welcome to the Monkey House, 1968
"America had changed in many ways, but it had yet to adopt the metric system"

Vonnegut's prediction of a future with 17 billion people...
 

Cthulhu.Science

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I didn't say there were people who don't use units. I'm saying that units of measure as descriptors make for fairly awful prose and have little connection to how impressed the characters are about that size, distance or amount of time. It isn't unrealistic for people to converse about numbers, just as it isn't unrealistic for people to talk about shopping lists and the neighbor's haircut.

But if you are writing something that is supposed to be entertaining, why include dry, lifeless data when you can suggest how that impressive thing feels rather than measures? What is the point of something being large if the characters or reader have no connection to it?
The covid social distancing signs often included images to go along with measurements for those who don't like units of measure. Some were funny - intentionally or not. But realistically, in day to day conversations how often do you really use units of measure. As story tellers, why would our characters use these units unless it is some sort of techno-babble.

image.jpg
 

Christine Wheelwright

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Addressing the second point first. Try this. Draw a line across a piece of paper. Mark 1/10th of the line. Try again, but mark 1/2, 1/3, and 1/4. Now, draw a short line. Draw another line that is 2x, 3x, and 4x. Repeat and draw a line that is 10x. Unless I'm mistaken, one will find that factors of 2, 3, and 4 are readily visualized, while factors of 10 are not.

Now consider time. The relationship between common units is certainly not decimal. The units are chosen on the question that one wants answered.

The relationships between various imperial measures are typically ratios of 2, 3, and 4. Nothing too exotic. The imperial system provides a wealth of individual measures that are coupled to the scope of whatever is being measured and can easily be scaled upward and downward. The metric system, though, has a sparser set of measures (I will assert that adding prefixes, such as centi- or kilo-, creates a new unit of measure).

The conversion factors between imperial measures are not that complex and the quantity of measures allows selection of units appropriate to the question at hand. Conversion factors only become complex when trying to switch back and forth between imperial and metric.

I don't think anyone is saying we shouldn't use convenient units (like light-years). I'm just saying that it should immediately stop when we have to do proper science or engineering (ie calculate something). I mean, even a beautiful and simple equation like E=mc^2 becomes useless if all you know is ergs, light years and pounds. Why would you want multipliers/constants everywhere when a beautiful system of units (the SI system) has been developed to simplify everything?

I want to say F=ma. I don't want to say F=kma (where k depends upon whether we are using furlongs per month squared and pounds, or chains per lunchtime squared and ancient Sumerian minas).

The debate about the base for our number system is completely separate. We have base 10 because we have ten fingers (the original counting machine). With hindsight, base 16 would have better prepared us for the computer age (using base 2 just makes numbers too long to fit on the back of a hockey jersey). Base 16 - or any other choice - would not have prevented the development of the SI system at all.

So, again, I'm not complaining that handy units like hours, days, light-years exist. But it does shock me that, particularly in some countries, these units are retained when actual calculations need to be done. This is 2023 not 1623!
 

Ursa major

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Speaking of being funny (or not) and
covid social distancing
(and bearing in mind that the BBC reporter whose name is mentioned below is 2.01 metres tall)....

There was the following exchange in the Coronavirus Miscellany thread:
Can’t they just use the traditional Hugh Pym measurement like the rest of us
I've heard that the Hugh Pym is not really appropriate for Covid-19...
...as it was specially created for the regulation of social distancing with regard to... er... Hugh Pym cough.... :rolleyes:
 

farntfar

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The parsec is certainly a unit that should get dropped in SF once we're not all living on Earth any more.
 

farntfar

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Along with metric, that also bases everything on the earth's size and gravity.
Fair enough at least for their origins!

So then we need to ask, can we assume that intergalactic man will retain the same size feet? :LOL:
 

Pyan

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Cthulhu.Science

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I suppose it's linked to using fewer parsecs to do the Kessel Run
In a galaxy using "hyperspace" this brag never made any sense to me. Is one "hyperspace" faster than another? Where is the skill that reduced time? Did he input the coordinates of the new location faster than anyone else?

Sure, it's a toss off line to show that Han Solo is a braggart. But it shows more about the writing as well.
 

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Wayne Mack

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Time suffers the biggest challenges away from Earth. Longer frame constructs such as day, month, year lose relevance on another planet. More problematic, though, is that time is a variable, a second is not a unit and has different durations in different relativistic frames.
 

farntfar

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Which means that there can never be units which are valid throughout the universe.
Either that, or the units are variable depending on their inertial frame, which would seem fairly sensible.
If crossing from one frame to another, you would have difficulty perhaps, but no more than the problems of grammar when time travelling.
So a unit can still be based on the second, and the distance travelled by a wavelength of light in x seconds.
Within each relativistic frame, a metre will be consistant with anything else in that frame, but not with anything seen from a different frame. But that is only to be considered normal anyway. And such the unit system remains useful.
 

Venusian Broon

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More problematic, though, is that time is a variable, a second is not a unit and has different durations in different relativistic frames.
Nope. The second is the unit, one of the seven fundamental ones that SI uses. It is defined by taking the fixed numerical value of the caesium frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s−1 (seconds to power of negative one).

Thus everyone that has this definition of the second, knows exactly how long a human second is in their own frame of reference. Note, this seems a bit obvious, but the caesium clock that you would use to actually generate a second is in the same frame of reference as the person needing such a measurement.

This definition does not change when you look at another person in a different relativistic/accelerating frame of reference. "It's not the units that are flexible and changing, it's spacetime itself, the actual physical reality of the universe, that changes to keep the speed of light constant." - quoting from Physics Stack Exchange
 

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