The Apprentice’s Guide to Physics: An Introductory Quest Through the Mechanics of the Universe

Unit prefixes are the verbal runes that shrink or stretch your units with a single syllable. They’re shortcuts to tame unwieldy measurements without changing their essence. Instead of writing out 3,000 meters, you can invoke the prefix kilo- to conjure “3 kilometers.” Instead of whispering 0.000000001 seconds, you can say “1 nanosecond” and sound like a seasoned chronomancer.

Prefixes are always attached to units, not to the raw numbers themselves. You won’t hear "nano" on it’s own; it always comes with a unit like "meter" or "second." This is because prefixes are like magical modifiers that alter the scale of the unit, not the number itself.

If you want to use unit prefixes in your written spells, prefixes come with their own symbols. For example, the prefix kilo- is represented by the symbol k, so "3 kilometers" can be written as "3 km." Similarly, "1 nanosecond" can be written as "1 ns."

You might wonder: if we can say “megagrams” instead of “a million grams,” why do we need both? The key is that they serve different roles in communication. The prefix name (like mega-) is part of the official SI system. It’s used when naming and writing units in scientific work: megameters, milliamps, nanoseconds. These are concise, precise, and standardized.

The decimal name (like “million”) isn’t part of the unit itself, it’s just how we describe the value of a number in everyday terms. You’ll often hear it in speech, estimates, or media. Saying “a billion cells” or “a trillion dollars” is easier for general audiences to understand than “gigacells” or “teradollars.”

So both ways are valid, but they’re used in different contexts. Prefix names are for units; decimal names are for quantities. And when you’re fluent in both, you can navigate smoothly between scientific scrolls and everyday storytelling.

Just add the power of ten to the unit or dimension value. For example, 550 nm = 550 x \(10^{-9}\) m.

It’s customary to not stack unit prefixes. For example, you would not say "8 kilokilogram", instead you would say "8 megagram" (8 x \(10^{6}\) g).

Be careful when communicating with synthetic beings, since unit prefixes used to represent different things in binary code. For example, 1 kilobyte used to be defined as 1024 bytes. However, those ancient scrolls have been updated to match our standard unit prefix notation. Now 1 kilobyte is 1000 bytes, and 1 kibibyte is 1024 bytes. It’s best to extablish a common understanding before engaging in data transfer.

One prefix to scale them all, one prefix to name them, one prefix to tame them all, and with the units frame them.