In earlier Sidebands I have tried, as our English teachers used to say, to “compare and contrast” related pairs of concepts that are sometimes mistakenly conflated. The first pair, Truth and Facts, are similar enough to make distinctions between them debatable. Even the language can twist you up once you start talking about true facts and false facts. The next two pairs, Good vs Like and Ignorant vs Stupid, are well-defined and distinct.
In all three cases, there are similarities and differences (hence “compare and contrast”), but a key difference between those and the current topic, Analog vs Digital, is that none of them are really opposite pairs. There is no Yin and Yang aspect to them; one does not exclude the other. I’ve already mentioned true facts. Something can be both good and liked (or neither). Someone can be both ignorant and stupid (being neither is both good and likeable).
As you’ll see, some things can have both aspects depending on how you look at them. Usually it depends on how closely you look at it. And if you recall the Yin-Yang discussion, analog and digital are opposing pairs, not “cup” pairs. They are truly exclusive concepts; one is not the absence of the other.
Simply stated: analog is a ramp, digital is a stair.
A ramp takes you up (or down) smoothly. If you roll a wheelbarrow up (or down) a ramp, it rolls smoothly, and you can stop at any point. A stair takes you up (or down) in steps. If you try to take the same wheelbarrow up (or down) a stair, it bumps from step to step. You can try to stop it between steps, but it invariably lands on one step or the other.
(And yes, I know you can forcibly hold it in place, the wheel hovering between steps, but that muddies the metaphor. Besides, your arms will tire, you’ll drop the thing and it’ll go bashing down the steps, spilling its load, maybe injuring someone and creating a lawsuit. See what you’ve started?)
The key here is the smoothness of the ramp compared to the distinct levels of the steps. When something is said to be analog it has that same smoothness. It can take on any value from high to low. Take light for example. It can be any brightness (or dimness). Many of us have light dimmers that allow us to select the level of desired brightness. Compare that to a light switch, which allows only off or on. An important consideration here is it is the switch that makes the light digital in nature; light itself is analog.
Temperature is another good example. Although we measure temperature in steps, called degrees, temperature itself is an analog quantity. We just round off the value to the nearest degree. And degrees are close enough that we generally don’t see much difference between 66 and 67 degrees (but consider the worried parent stressing over a child’s 100.2 degree fever).
Distance is another analog quality we measure off in units: millimeters, feet, yards, miles, light years. But two things can be any distance apart. It all depends on how closely you want to measure them. The same can be said for pressure, weight, speed or musical pitch. We measure them in units, but they exist as smooth qualities.
Generally speaking, our world is analog. It is only when we measure it, talk about it, that we mark it off in units.
There is such a thing as an analog computer, but most computers—at least the ones you think of as computers—are digital. There are some technical reasons for this, but it boils down to being the same reason we mark the analog real world off in units: it allows us (and them) to talk about light, temperature, pressure, and so forth.
A ramp is not a stair, and a stair is not a ramp, but both take you up and down. That’s what makes them Yin/Yang opposites. One excludes the other despite having related functions. (Recall two other such pairs: up and down. Moving up excludes moving down but both change your altitude.)
But what if you stand far enough away from a stair that you can’t see the individual steps? That stair looks like a ramp. Or what if you make a ramp with tiny steps too small to be seen without a magnifying glass? That ramp is actually a stair. In both cases you simply can’t see the steps.
It turns out the real world is like that, too. Quantum physics is the discovery that the real world is made of tiny steps. Despite our everyday experience, reality turns out to be digital. Any ramp, is made of atoms, which are extremely tiny steps (far too small to be seen with any magnifying glass). The atoms are also made of much smaller bits, called sub-atomic particles.
Even light, temperature, pressure and pitch turn out to be quantized. That is, they also consist of tiny steps. For example, you may have heard of photons. Those are the steps that make up light. It is harder, and very technical, to describe how temperature, pressure and pitch (let alone distance and speed) are also quantized. For now take my word for it that they are.
The real world… looks analog to us, but it’s really digital if you look closely enough.
I’ll leave you with this:Imagine an orange. Now make the orange bigger and bigger until it’s the size of the whole earth. If you did that, the atoms in the orange would be the size of cherries.
Try to imagine the whole earth made of cherries. Think about how many cherries it would take to make your house, your town, your state, your country, the whole earth including the seas, the mountains, everything made of cherries. (Yes, we’re talking about gazillions of them.)
That’s the scale we’re talking about with atoms: Orange → Earth; Atoms → Cherries.