From Stock Markets To Ledgers, Part III: Time

I find Feynman’s quote that “nobody understands quantum mechanics” a bit silly.

Quantum mechanics’ main tenet, the idea that an electron can be both a particle and a wave, is actually quite intuitive. And there’s plenty of real-world analogies that make it familiar, even obvious.

Let me give you a very simple one: language.

Most European languages divide concepts into (roughly) two camps: nouns and verbs¹. There’s oil and water, and you can run and cook. These are two separate camps that describe things in the world, and actions being performed.

But you can also oil your car and water your plants; and you can go for a run, and work as a cook. There’s a fluidity in the language where the action being performed and the object related to it revolve around the same concept, and both noun and verb are a manifestation of being the thing and doing the thing.

You milk a cow to get milk, after all.

Let me give you another: the economy. Money can be exchanged for goods and services: you can buy peanuts, and you can hire a VA to handle your email. But you can also pay a Netflix subscription, which is a product that consist of being able to watch movies on demand, or you can pay a consultant for one of their productized services. You can DoorDash food to your place rather than having to go to a restaurant (and DoorDash is now a verb, see what I did there?).

Money is the abstraction of being able to buy, and it becomes concrete in the things we buy: be it goods, services, or anything in between.

You probably see where I’m going with this, but let me give you one last example: your body.

When you get a blood test, the results tell you, among other things, an estimation of how many white cells there are in your body, and of which kind. This tells you a lot about your immune system, and could signal a lot, from having a cold to AIDS or leukemia.

But the thing is, the number of white cells in your bloodstream is pointless. What matters is that they’re there to do something. The presence (or absence) of white cells is meaningful to the extent that white cells are produced by your body to protect your organism from external agents. The only reason we count them is because it is impossible to see white cells in action, and we can only infer what’s going on from counting them. The presence of white cells and what they’re doing are two manifestations of the same thing: a bodily response to the environment.

Electrons being particle and wave is analogous to all that. What we perceive is an incomplete manifestation of a whole. We milk to get milk; we buy things and jobs with a number in our bank account; we have white cells to defend ourselves.

Objects are tangible manifestations of state. We see how they are now, and we see them doing things. Processes are elusive manifestations of time. We know that something has happened because the state is different from what it was before.

We perceive time by noticing that things aren’t the way they used to be.

Quantum mechanics isn’t Tenet levels of hard². It’s just that humans are really bad at thinking about processes.

When I was talking about money, was it simpler for you to think about buying stuff, or hiring somebody? Doesn’t it feel like astronomy is more about stars and planets than it is about supernovas and the gravitational pull? Isn’t your body simpler to think about in terms of organs rather than hormones?

Yes, yes, and yes. Humans unconsciously prefer to think about the world in terms of objects, rather than processes. Structure, rather than behavior.

The same exact bias happens, of course, to software engineers. And that is a pity, because stock markets, and ledgers, aren’t about objects. They’re about processes.

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This article is Part III of the From Stock Markets to Ledgers series, where I’m going deep into the design and implementation of stock market systems, not only because it’s so interesting and fun, but also because there are lots of good lessons for those building ledger systems.

In today’s article, I’ll focus on one interesting aspect of stock market system design: how central time is, and how bad humans are at reasoning about it.

We’ll look at:

• What HR organizing the Christmas dinner and Apache Flink have in common

• The 4 notions of time (you’re probably storing only one)

• The trade-off between quickness and completeness

• Two useful approaches to engage in it: watermarks and snapshots

• And a useful takeaway for ledger builders

Enough intro, let’s dive in.