When it comes to Apple products, how thin is too thin?

One of the characters in Neal Stephenson’s novel Snow Crash uses knives with edges a single atom thick, so sharp they can cut through anything. I think about those knives every time Apple announced a newer, thinner MacBook or iPad or iPhone.

Each new generation of Apple product strives to be thinner and lighter than the product that it’s replacing. It isn’t always possible, but it’s clearly a goal that drives Apple’s product design decisions.

And look where it’s taken us. Introduced in 1991, the PowerBook 170 weighed 6.8 pounds and was 2.25 inches thick. Ten years later the Titanium PowerBook G4 was a staggering “one inch thin” and weighed 5.3 pounds. Nine years later the MacBook Air was .68 inches at its thickest point and weighed 2.4 pounds. And the new MacBook is .52 inches at its thickest point and weighs 2.03 pounds.

Similarly, the full-sized iPad has reduced from 1.5 pounds to .96 pounds, and an iPad mini weighs just .69 pounds. Smaller and smaller. Meanwhile, the iPhone keeps shrinking in one dimension while growing in the other two–all to create a bigger screen for us to view (and make finger gestures on).

This approach has served Apple well, and customers seem to like thinner, lighter things, too. And yet I keep wondering where this trend ends. Let’s assume that a future MacBook won’t be a single atom thick, capable of slicing your enemies in two like those knives in Snow Crash. How thin is too thin?

There’s always a trade-off

I love my MacBook Air. It appeals to me in part because it’s so thin and light. But Apple’s pursuit of thinness and lightness has consequences. Thinner and lighter devices have smaller batteries, low-power processors, and reduced space for ports and plugs. The new MacBook features a keyboard with dramatically reduced key travel, apparently due to size constraints.

This isn’t yet another article about the MacBook, though. It’s about the logical continuation of Apple’s drive to get thinner and lighter. This has got to stop at some point—assuming that Apple’s not going to create a monomolecular laptop that you can throw like Oddjob’s hat. The question is, when?

For a while now, Apple’s shot for a baseline of battery life while making its devices thinner and lighter. Once the company decides that there are no thinner worlds to conquer, would battery life begin to increase? Or will Apple continue to strive toward thinner, lighter devices, even as the returns diminish rapidly as both weight and thickness approach zero?

Apple’s capacity for change is one of the things I admire most about its corporate culture. I do wonder, sometimes, about how Apple will adapt when it discovers that it’s becoming increasingly difficult to make products thinner and lighter. Will Apple notice when the sacrifices necessary to make those products begin to outweigh the benefits? What will be the moment of realization that the quest for thinness and lightness has reached a stopping point?

Then again: last year Apple filed a patent for a next-generation periodical reader with a flexible display. So maybe we’ll be seeing Apple devices so thin they could give you a paper cut.

Perhaps the most fascinating part of this issue is how Apple’s drive for technological advancement inevitably clashes with our own biology. Human bodies haven’t changed much in 200,000 years. Our eyes are imperfect and get worse with age. Our hands come in a limited range of sizes, our fingertips are small, and we only have so many fingers.

In the end, maybe the Apple Watch (which has quite a bit of room to get thinner itself!) suggests a different way forward, with smaller tech products scattered everywhere. Once there’s a touchscreen display and microphone on your wrist, and a tiny wireless speaker in your ear, and a thin-but-not-too-thin iPhone in your pocket, measuring and weighing every separate component of that constellation of devices might seem completely unimportant.