Why Every Sci-Fi Interface Is Made of Glass

In 1999, Steven Spielberg put fifteen experts in a hotel in Santa Monica for three days and asked them to imagine 2054. The think tank was convened by Peter Schwartz and Stewart Brand. The film it fed, Minority Report, came out in June 2002, and one thing from it escaped into the world and stayed there.

It was a computer you didn't touch. Tom Cruise stands in front of a transparent wall of images, wearing gloves, and sweeps video clips about with his arms. The man who designed it was John Underkoffler, an MIT Media Lab researcher who served as the film's science and technology advisor. According to the film's production history, Spielberg had asked for something "like conducting an orchestra".

Underkoffler wasn't making it up from nothing. The gestural system he was developing at MIT, which he called g-speak, was real enough that the film's version was later described as a working system rather than a special effect. After the film he turned it into a company, Oblong Industries. By 2011, MIT Technology Review found Oblong selling to the military, financial firms and oil and gas companies, who needed to move around very large amounts of data. It was an impressive, expensive and rather lonely success.

Meanwhile, the rest of us got something else. We got a slab of glass that we poke with one finger. This essay is about the gap between those two futures, and about the strange fact that they were both made of the same stuff.

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Start with the stuff. Why is it always glass?

Look at a decade of screen fiction and the pattern is hard to miss. The interface is a sheet you can see through. In Minority Report the images float on a transparent wall. In a thousand concept videos since, the tablet is a window and the window is a tablet.

There is a boring reason and a good one. The boring reason is that film needs the audience to see two things at once, the data and the person reading it. A transparent display lets a camera shoot the face through the information, so the actor is acting and the screen is explaining in the same frame. Glass is the cinematographer's material. It is the one surface that is a window and a screen at the same time. That's our reading, not a quote from any production designer, but it is hard to see what else would explain how uniform the habit is.

The good reason is that glass says something about what a computer is for. A wooden console says operate me. A glass pane says look through me. The fantasy in all these films is a computer that has dissolved. It is not a machine you work, but a clear layer between you and the information, which you can reach through. The computer is finally the window it always pretended to be.

Which makes the real history of glass in computing a small joke at the future's expense.

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The first touchscreen you could drive with a finger was described in 1965, in a short article in Electronics Letters by E. A. Johnson of the Royal Radar Establishment in Malvern. So the touch interface is older than the film, older than the Macintosh, and older than most of the people now complaining about it.

What followed was a long wait for the right pane: thin enough, tough enough, clear enough. The pane we use now began in a different kind of corporate dream.

In the 1960s Corning developed a chemically strengthened glass called Chemcor. According to Corning's own history, it was intended for phone booths, prison windows, eyeglasses and car windscreens. Look at that list again. Every item is something you look through. Nobody dreamed of a glass that people would look at, for hours, held a hand's width from the face. Chemcor was a material for windows, and it wasn't thought suited to consumer electronics.

Then, in 2005, Corning revived the experiments to see whether the old glass could be made thin enough for phones. By the usual account of the story, Steve Jobs complained, after the January 2007 unveiling, that his plastic-screened prototype had scratched in his pocket. Glass shipped on the first iPhone in June 2007. In February 2008 Corning gave the material a name: Gorilla Glass.

So the pane we stare at all day is a window material, repurposed. The glass was made to be transparent, and we have spent fifteen years making it opaque with our attention.

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The strangest thing about this story is a short film. In February 2011 Corning showed a video called A Day Made of Glass at an investor day in New York, and then put it on YouTube, where it was watched by millions. By February 2012 the industry press was reporting well over 17 million views, which is astonishing for a corporate video about a material.

The film is Minority Report's grammar sold as a product catalogue. It follows a family through a day in which ordinary surfaces turn out to be touchable glass. Corning itself was candid that many of the ideas weren't about to ship and still needed research, demonstration and price cuts. But that was never the point of the video. The point was to put the pane into your imagination, so that when someone asked for one, you'd already know what it looked like.

That is what fiction does to the future when it works. It doesn't predict. It places an order. The glass in that video was a picture of a shopping list, written in a grammar the public had already learned from the cinema.

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And yet the thing nobody ordered is the part that won.

Look at what Minority Report actually asks of its user. Cruise stands. His arms are up. He moves them, gracefully, for as long as the scene lasts. In a film that is a few minutes of lovely choreography. At a desk, for eight hours, it is something else, and interface designers have a name for it. They call it "gorilla arm": the fatigue that sets in when a gestural or vertical touch interface asks you to hold your arm out with nowhere to rest. Early pen-based computers had it. The usual remedy is to let the user rest a hand or an arm on the device or its frame.

The iPhone is a gorilla-arm cure. You hold it low, in the lap, on the table, in the crook of the elbow. You can use it on a train, with your head down, with one thumb, for hours. It asks for almost nothing from the body, and that, we'd argue, is why it beat the orchestra. The future that won wasn't the most beautiful gesture. It was the one that tired you least.

That is a useful rule for anyone reading a near-future film for hints. Ignore the most spectacular interface in the frame and ask which one a body could stand to use at the end of a long day. Fiction optimises for the eye of the audience. Real life optimises for the elbow of the user.

We should be a little careful about declaring victory for the pane, though. Minority Report got a few things wrong in the other direction. Its interface is for experts. It is a professional instrument, a conductor's podium, and in the last reporting we found, in 2011, Oblong was still selling it that way. The pane that won is the one a six-year-old can use, and a six-year-old can use it because it asks nothing of them but a finger. The price of that ease is that it asks very little for them either. A pane that's easy to touch is easy to keep touching.

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So where does the glass go next?

The usual answer is that it comes off the table and onto the face, which is the old film-set logic carried to its end. If the dream was a layer between you and the world that you can reach through, the logical home of that layer is the lens. Headsets and glasses that overlay information onto what you see are already on sale, and they are what the fiction has been drawing all along: not the slab you look down at, but the pane you look through.

We think this is where the fork is, and it's worth stating plainly. The slab in your hand has one virtue that is easy to miss. It is an object. You can put it down, turn it face-down, leave it in another room. The film-set pane has no such edge. Once the glass is the window, there is nowhere to set it down, and every default about what appears in it becomes a default about what you see of the world. (We wrote earlier this week about how little we notice the defaults that already govern us. This is the same story with the stakes raised to eye level.)

One branch is quiet. The pane keeps its promise: it dissolves, it shows you what you asked for, and it goes clear again. The other branch is the one the Minority Report billboards already warned about, where the clear layer is the most valuable advertising space ever sold, because it sits between you and everything else.

Nothing about the glass decides which branch we get. The material is neutral, as it was in the phone booth. What decides it is the boring list: who owns the layer, what it shows by default, and whether there is an off position that is easy to find and honest about being off.

In the mid-2020s, people still talked about "screen time" as if the screen were the problem. It never was. The problem was the pane's position, between you and the world, and who gets to write on it. The next decade will move that pane from the hand to the eye. Make sure it ships with a frame, and an edge, and a way to set it down.