Units of measurement in a non earth centric universe.


Only Saltwater Fish Drink
Jan 24, 2016
Seconds, minutes, hours, days, weeks, years and so on. These are of course all very earth centric. No in the process of world building I have tried to create a new measurement system that has is not based on the rotation of any planet or its orbital period.

My universe is essentially this one but many thousands of years in the future. As such the basic physical laws of this universe are the same as my universe. Currently a second is defined as 9x10^9 transitional periods (to 1 sig fig) between the two hyperfine energy levels of a ground state caesium 133 atom. Clearly caesium is the best element to use to define a unit of time, primarily due to its electron shell configuration. Of course the second comes originally from the subdivision of an hour, and ultimately day.

My New Unit, Let’s call it a Tip (I haven’t decided what terms to use yet.) will be my fundamental unit for the measurement of time. 1 tip will be 1x10^8 oscillations of a caesium atom exactly. Thus a tip is around a 9th of a second. Normal convention then applies so a DecaTip would be close to a second. However, I find this a little clumsy so I will use terms for each increase in magnitude from a tip.

1x10^1 Tip = 1 Top

1x10^2 Tip = 1 Tap

1x10^3 Tip = 1 Trip

1x10^4 Tip = 1 Trop

(as I said these would not be the terms.)

At this point I stopped. It suddenly occurred to me that this creates a few issues.

Firstly, I would have to rework any derived units i.e. any unit of energy or anything else which is calculated using seconds. I have no problem doing it but is it worth it considering the third point.

Secondly, why stop with time? And considering that a meter is an earth centric measurement this is going to throw reworking other units into a whole new level of complexity,

Thirdly, does all this take the reader completely out of the story. At no point does the narrative lend itself to explaining this so it would just be the terms used. There would be some conversions to the relevant planet, or orbital stations local time but we think and understand time in earth units and we understand distances in kilometres or miles.

By creating my own units of measurement am I simply satisfying my own need for thoroughness, and my own ego a tad?

Has anyone else thought much about this?

Edit: So non Earth centric I have repeatedly failed to Capitalise the the e in Earth.
all this take the reader completely out of the story

Yeah, that's the problem with completely invented measurements. If only used a couple of times, context should allow some sense of scale - but used too often then unfamiliar units are in danger of simply confusing.

At the end of the day, the writer has to act as an interpreter of sorts for the reader, in order to properly communicate all of the required information. Sometimes this requires a degree of compromise, but it all depends on context.
Is this all key to the story? Or are you simply wanting to make your story's setting look less familiar?

If it's the latter, aren't there better ways of doing it -- e.g. in the story or in the actual setting -- than making the reader have to remember the difference between tip, top, tap, trip, trop, etc.?

(Now if the main character, a Tip-top Tap merchant on a sales trip, was having trop difficulté with his French speaking prospective customers....)
1) Having gone through a physic degree, where to trip up the unwary we would be very occasionally be given questions in different systems of units, you would be amazed at how different your equation's actually look even when you change the main unit from, say, metres to centimetres. (Not in 'structure', more in 'dressing' - 1/r^2 law has the same basic form!) but it can perplexing when you lose all sorts of 4 PI's and have to work with very strange constants. But that's science, not novel writing...(see point 3!)

2) The metre definition and second (but not currently the kg at the moment, although I think they are working on it) is no longer Earth-centric in it's definition, but of course it is very, very close to an arbitrary length & time that we cooked up :D. Messing up other units just makes it a bit of a headache frankly IMO!

3)... at the end of the day, when you write your story will you actually ever use any of this at all??? If you are only mentioning it, because you came up with it and you think it might be interesting to readers, but really does not add to plot or character, it very probably shouldn't be there at all.

In fact if you are determined to have characters talking: 'the station is 12 NegKegs away and we'll reach it in 40 flartybarbs'* it will likely just add a layer of confusion that could throw readers out of your world.

I remember a PKD novel that starts with a bizarre unit of temperature...it's effect was to make the future alien and different, but he didn't expand on that and use it again. Which was fine.

Basically however, I'd not worry about it and see what comes up in the finished draft. My guess is that it won't really come up - unless you are determined to squeeze it in (and from my own experience, I'm cutting out tons of stuff I thought would be interesting and squeezed in!)

* I have no idea exactly how you would do this in your novel, and I'm being a bit blunt and clumsy with my example! But you get the general idea :p
I think you need to look at how measurement systems come about - an awful lot of the time it is practical convenience and historical accident. So, for much of the world, the meter and it's multiples/fractions have replaced the yard/foot/inch, but the resulting 'common' ones in use are of similar physical scale to the old ones, because those are the sort of sizes people use daily. So a meter is very similar to a yard, a centimeter not too much smaller than an inch, a kilometer a bit shorter than a mile. If we were going to go with a 'rational' measurement system, volume ought to be generally referred to in cubic meters, but for a lot of daily use that is far too big, so we have cubic centimeters, down on a similar scale to the old fluid ounces, and the litre instead of a pint. Even if the law was written to require cubic meters to be the unit of volume, how long would that last? Walk into a bar (somewhere else in Europe, because we still cling to imperial measures for our booze) and ask for five ten-thousandths of a cubic meter of beer...

Really, if you are going to invent new units, they need to be practical ones, and you only new the few that are going to be critical to your story. If you are reasonably inventive, you don't even need to tell the reader how big a tip/tap/top is because the context will tell them.

Adding to Venusian Broon's point about units and changing all the equations to match - the transition from 'old' measurement systems to metric did exactly that. Not too many years before I was studying physics in the UK, everything was in feet, pounds, ergs, dynes... and then someone had to re-write all the text books. Yes, it can be done, and if your story is about that then the detail is important, but otherwise it is not going to add anything.

The other thing to consider is where your units are going to be used. If your story is set on a planet, then the locals are probably going to have a system of time measurement that relates to the planetary rotation, because otherwise you end up with "it's five past two, so that means this is tuesday this week..."

If you are purely space-based, then you have more freedom, but my loose understanding of the way humans function is that we don't cope well with a sleep/wake cycle that deviates too far from a twenty-four hour one, so a space-based humanity might well define their clocks and calendar to be something close to an earth-based one for things like day length. (Perhaps we have a biologist or behavioural experts who can set me straight on this one.)
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Walk into a bar (somewhere else in Europe, because we still cling to imperial measures for our booze) and ask for five ten-thousandths of a cubic meter of beer...

Personally I prefer a litre of beer to a pint, not just because it's SI related...but then I'm a large man who can, on occasion, can be 432 cl thirstier :rolleyes:
This has been discussed several times before and never ends happily.

If you want to mention non human units of measurement, do so, but don't try to explain them, or work out an entire system (unless it is for your own enjoyment, if it is, the go for it!), just have people say the things occasionaly (but please, please don't italisize them) and let it go. Just dont do it too often, or, as people have said, it is just a burden on reading.

Lots of books, films and tv shows have done it, so its fine. Just dont make it an issue. And, don't let it take your time, time better spent writing the story.
I think having seen everyone's pretty unanimous opinions it confirms what I thought, totally takes the reader out of the story. I may one day go into further detail for my own satisfaction but it would in no way drive the story forward and therefore shall not appear in it.

Venusian Broon. From what I recall from my degree I believe they were going to use plancks constant to define the kilogram, that was some time ago though. A quick google shows there's now another method under consideration. Now they're looking at two methods I expect there to be a huge bun fight before we get a new definition. I will miss being able to go to paris and see the Actual Kilogram though, although it will still be there and always have a place in my heart.

I find definition of units fascinating and that's why I've fallen into this trap.
Unless you are planning on writing the story in an alien language as well, why leave alien measurement units untranslated into Earth equivalents?
Unless you are planning on writing the story in an alien language as well, why leave alien measurement units untranslated into Earth equivalents?

I did actually thing of creating an alien language, written in alien glyphs. I realised how ridiculous that would be long before realising i was effectivley doing the same with units.
Don't Call A Rabbit A Smeerp. If you must, put a note in the foreword that the story has been translated into Earth English. Then use everyday words.

^ this.

Basically all stories in the fantasy genre, and many in the sci-fi genre, are implicitly translated into a format readers can understand. Obviously all the aliens don't speak english, and distant future humans probably have hugely different dialects, words, idioms, etc. Units might be different, pronunciation might be different, and common tools and things may have come to new names. You could just drop all this on the readers as an exercise in hyper-realistic world building, but it doesn't make for very good storytelling.

Given that stories are implicitly translated anyway, I'd say only break that pattern when it adds to the story or the ambience/tone... e.g., an idiom that came about after world war 3 might create a cool tone and imply a particular backstory... but if the name of a "chair" changed to "butt holster" sometime in 2300CE I don't see that adding enough that it is worth making the reader learn it. I suspect all new distance units don't add too much either.

As far as physics is concerned, yeah your constants go haywire, but your basic equations don't change all that much. Units cancel and correspond, so it doesn't have much of an effect on anything in that sense. Coming up with all new names for units would be a project.
I think that altering time and measure for the sake of creativity is a tricky slope. For the reader these new measures are confusing at best.

Its like a protracted info dump. No one wants to do math in the middle of a story. This is why units of measure whether distance or time are seldom altered much by mainstream authors, by the movie industry, or others involved in science fiction.
Time gets tricky when you have interplanetary travel at the best of times. Dont make it harder for yourself.
But i know you're all thinking it's been 30 Treps since I posted that first message.
The problem is that we just switched to quantum treps savings time. Always confusing which way to set the watch...

The only really natural units are those based on fundamental constants of the universe, with all of them set to 1 and the size of the units adjusted to match. The problem is that the units then become impractically small, or impractally large. Example; the natural unit of time is the Planck time, which is around 1E-43 second IIRC.

Slightly less rigorous, use something which is universal. This was tried in the various messages attached to Pioneer 10 and the Voyagers; use various properties of the rather ubiquitous hydrogen as a base. Such as, for example, the wavelength of what we call 21cm radiation as your length unit.

However, I think that for any likely civilisation the units will be arbitrary, based on physical conditions on its home planet at best. It's possible that the units would be re-defined (with awkward numbers involved) using more fundamental properties of the universe involved which are more possible to measure to many significant figures.

Example: The centigrade (now Celsius) scale was defined as being based on the properties of pure water; at standard pressure (roughly, average atmospheric pressure at sea level) 0 degrees is the freezing point of water and 100 degrees is its boiling point. (Pressure is really important for this; as a slightly silly illustration, because I spent from ages 5-9 in the central area of South Africa which is at around 1500 metres, I remember my mum always moaning that she couldn't make a decent cup of tea!)

Now, the unit is called Kelvin. The zero point is a natural one; absolute zero. But the size of the degree is defined from the fact that the triple point of water (another natural constant) is 273.16 K. The peculiar number comes from the earlier definition of the centigrade degree. We can't make the numbers more sensible, without having to re-write all manner of tables and other data.

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