But beyond those little efforts, most of the technology on the show seems to have come as an afterthought. "No one was probably thinking about, you know, what kind of mouse should we use, or where should it go in the room," says Thompson. They just represented whatever was the norm of the time, and, in doing so, documented details of computer history that perhaps no one at the time could have articulated—details that were so commonplace they went totally unnoticed.

For instance, when computers appear on Law & Order in the early '90s they are often not on. Who at the time would have said, "We have these new machines in the office. We only turn them on when we need to use them, and they are off the rest of the time." The fact that computers tended to be off is only noticeable in light of today's habit of leaving them on, even during a task that is not specifically on a computer (which may not even happen that often anyway). People's work-streams were not computer-based, and computers only were booted up for a specific task.

Another shift Thompson noticed is that over time, computers attained more prominent physical locations within a room. Early on, computers tended to be off to the side, on a specialized desk, perhaps for many people to share, using it for one specific task. If a character had his or her own computer, it would be located on a separate table behind his or her desk, not on the desk itself. It's not until 1995 that the first computer makes the leap from behind the desk to its central "desktop" position we all are so familiar with today.

That shift, from out-of-sight-out-of-mind to office-place centrality, dovetails with another: Over time, people became more social as they interacted with their machines. What does this mean? In the '90s, Thompson says, it's very infrequent that you'll see someone using a computer with another person present. If a computer is on, it's running in the background, as though to indicate that someone got interrupted while using it solo. In more recent seasons, people seem to be more comfortable using computers in the company of others. You'll often see two detectives working on two laptops sitting right across from one another, and, ubiquitously, people nonchalantly checking their phones mid-conversation with those around them.

When all was said and done, Thompson decide to run the math: How much of Law & Order had he captured? His calculations are a bit back-of-the-envelope, but illustrative nevertheless. The show ran for roughly 1,149,120 seconds. Standard video frame-rate is 29.97 frames per second, and he had 11,000 frames, or 0.007 percent of Law & Order. Of course, he didn't capture every single frame in which a computer appears, but, he says, "it gives you an idea of actually how little time the computers are on screen, compared with the whole rest of the show."

Which, for Thompson, points to a central observation about his project: It wasn't really about Law & Order at all—"It's about technology, and our culture, and ways that we can look for records of our relationship to those things in places we wouldn't normally think to look for them, which we wouldn't be able to find elsewhere." For 20 years, Law & Order documented the air around us. We don't have books or academic articles about the details Law & Order captured; they were invisible at the time.