When I was studying special relativity one of the things which caught my attention was how, because the speed of light  was a constant, you could just set it to . Setting c equal to 1 caused space and time to have the same units. One nanosecond is slightly less than to one foot. The Lorentz Equation  is beautiful when written with .

I started designing a system of absolute units. My system would be elegant. No more would humanity's perspective be shackled by our pre-relativistic Dark Age units of measurement.

About halfway through the design process I realized I was designing a bad system. My units were impractical. Not (just) because of the coordination problems required to actually get everyone to change units. Not (just) because Plank's Constant  is over thirty orders of magnitude shorter than the distances we use for everyday tasks. My system was fundamentally broken because the inelegant space-time non-equivalence of real-world units is a feature, not a bug.

Suppose we used the same units for time as for distance. Meters are replaced with nanoseconds. If I say something is "fifteen minutes away" it's no longer obvious whether I'm talking about a fifteen-minutes of time or the distance from the Earth to the Sun and back again. Usually whether I am discussing space or time can be inferred, but inference shouldn't be necessary. The purpose of language is to communicate effectively the first time. A little bit of redundancy improves communication.

The world is a complex place. The reason things are the way they are is often non-obvious. That's why if you propose a change to the world then the burden of proof is on you to fill in all of the burdensome details.

I think the burden of worldbuilding is why the philosophy in science fiction tends to be so good. Science fiction authors are required to worldbuild which forces their ideas to be somewhat grounded in reality.

26

10 comments, sorted by Click to highlight new comments since: Today at 5:11 AM
New Comment

A nice example of this idea is "dimensionally-equivalent units" where people use different words for fundamentally the same unit depending on what it's measuring, purely for better communication. Examples include Becquerel vs Hz, Newton-meter (torque) vs Joule (energy), Volt-amperes (in AC electricity) vs Watt (power), ohm (resistance) vs "ohm per square" (sheet resistance), etc.

Litres per km vs. mm is another good one. The fuel consumption of your car can be visualised as a thread of petrol stretching ahead of it, burned exactly as fast as the car sweeps it up. The typical 10L/100km is 0.1 mm, about the cross-section of a monofilament fishing line.

Were you trying to do anything more interesting than the widely used system of natural units? The main purpose of that system is to save chalk and physicist brain power by avoiding the mention of all pesky factors of c, G, h, k_b, etc. that appear is all physical equations. Basically all particle physicists use that system of units everyday, and have been doing so for decades.

I was trying to adapt natural units for everyday use.

What made you believe that they could be suitable in the first place?

Because units are (somewhat) arbitrary.

If units are somewhat arbitrary that still implies an infinite possibility space. Why did you believe you were likely to discover an overall improvement in finite time?

One nanosecond is slightly less than to one meter.

No, one nanosecond is slightly less than one foot.

Fixed. Thanks.

Disambiguation is a great feature of language, but we can also opt instead to make things maximally ambiguous with my favorite unit system: CCC. All measurements expressed with only the letter C.