Light: it's the radiation we can see. The communications potential of light is obvious, and indeed, many of the earliest forms of long-distance communication relied on it: signal fires, semaphore, heliographs. You could say that we still make extensive use of light for communications today, in the form of fiber optics. Early on, some fiber users (such as AT&T) even preferred the term "lightguide," a nice analogy to the long-distance waveguides that Bell Laboratories had experimented with.

The comparison between lightguide and waveguide illuminates (heh) an important dichotomy in radiation-based communication. We make wide use of radio frequency in both free-space applications ("radio" as we think of it) and confined applications (like cable television). We also make wide use of light in confined fiber optic systems. That leaves us to wonder about the less-considered fourth option: free-space optical (FSO) communications, the use of modulated light without a confined guide.

Well, if I had written this two or three years ago, free-space optical might have counted as quite obscure. The idea of using a modulated laser or LED light source for communications over a distance is actually quite old. Commercial products for Ethernet-over-laser have been available since the late 1990s and achieved multi-gigabit speeds by 2010. Motivated mostly by Strategic Defense Initiative and Ballistic Missile Defense Organization requirements for hardened communications within satellite constellations, experiments on a gigabit laser satellite-to-ground link were underway in 1998, although the system ultimately only provided satisfactory performance at a rate of around 300 Mbps. As it turns out, FSO computer networking is nearly as old as computer networking itself, with a 1973 experimental system briefly put into use at Xerox PARC.

Despite the fact that FSO systems have been generally available and even quite functional for decades, they remained a niche technology with very little public profile until the phenomenon of low-orbit communications constellations (namely Starlink) put the concept of intra-satellite laser communication into the spotlight. Despite various experimental satellite-to-satellite systems dating back to the early 2000s, and more or less clandestine military applications over the same period, the first real production system is probably the EU's EDRS, which went live in 2016. Starlink didn't really get the laser technology working until 2022. That's one of the interesting things about FSO: it seems intuitively like it should work, it does work, but it's a technology that has often sat dormant for many years at a time.

Years ago, when I was in college, I had one of those friends who never quite had it together. You know the type; I'm talking lost a debit card and took three months to get a new one because of some sort of "mixup" with the credit union that I think consisted mostly of not calling them for three months. In the mean time, our mutual friend ended up in a quandry: at WalMart, at one in the morning, with a $2 purchase and no cash. Well, this was no problem for that particular space case: he had his checkbook.

If you think about it, it's actually pretty remarkable that grocery stores accept personal checks. It's a very high risk form of payment. Even if the check is genuine, the customer could be writing it against an empty account. On top of that, with modern printers and the declining use of MICR, forging checks is trivial. When you offer a check, the retailer has very little to go on to decide whether or not you're good for the money. Surely, fraud must run out of hand—and yet, just about every major grocer still accepts personal checks.

Retail point-of-sale acceptance of personal checks is the product of an intriguing industry that handles all the challenges of checks at once: a combination of digital payment network, credit reporting firm, insurer, and debt collector known as a check guarantee service. The check guarantee is older than the ATM, and depending on how you squint, check guarantees are quite possibly the first form of real-time, telecommunications-based point of sale payment processing.

Harry M. Flagg was born in Frankfurt in 1935, but spent most of his childhood in Milwaukee, Wisconsin. He attended MIT, major unknown, and graduated in 1957. I think he was probably an ROTC student, because some sort of Navy service took him from Massachusetts to Hawaii, where just a few years later he was out of the Navy and working as some sort of "management consultant." Flagg was entrepreneurial to his core, so while I knew few details about it his consulting work is unsurprising given the wide variety of business ventures he was soon involved in. We can be fairly confident, though, that his clients included retailers—retailers who struggled with personal checks. In 1964¹, Flagg quit consulting to focus on checks alone.

I tend to focus on the origin of the computer within the military. Particularly in the early days of digital computing, the military was a key customer, and fundamental concepts of modern computing arose in universities and laboratories serving military contracts. Of course, the war would not last forever, and computing had applications in so many other fields—fields that, nonetheless, started out as beneficiaries of military largesse.

Consider education. The Second World War had a profound impact on higher education in the US. The GI bill made college newly affordable to veterans, who in the 1950s made up a large portion of the population. That was only the tip of the iceberg, though: military planners perceived the allied victory as a result of technical and industrial excellence. Many of the most decisive innovations of the war—radar and radionavigation, scientific management and operations research, nuclear weapons—had originated in academic research laboratories at the nation's most prestigious universities. Many of those universities, MIT, Stanford, University of California, created subsidiaries and spinoffs that act as major defense contractors to this day.

Educational institutions bent themselves, to some degree, to the needs of the military. The relationship was not at all one-sided. Besides direct funding for defense-oriented research, in the runup to the Cold War the military started to shower money on education itself. Research contracts from uniformed services and grant programs from the young DoD supported all kinds of educational programs. For the military, there were two general goals: first, it was assumed that R&D in civilian education would lead to findings that directly improved the military's own educational system. Weapons and tactics of war were increasingly technical, even computer controlled, and the military was acutely aware that training a large number of 18-year-old enlistees to operate complex equipment according to tactical doctrine under pressure was, well, to call it a challenge would be an understatement.

In the United States, we are losing our fondness for cash. As in many other countries, cards and other types of electronic payments now dominate everyday commerce. To some, this is a loss. Cash represented a certain freedom from intermediation, a comforting simplicity that you just don't get from Visa. It's funny to consider, then, how cash is in fact quite amenable to automation. Even Benjamin Franklin's face on a piece of paper can feel like a mere proxy for a database transaction. How different is cash itself from "e-cash", when it starts and ends its lifecycle through automation?

Increasing automation of cash reflects the changing nature of banking: decades ago, a consumer might have interacted with banking primarily through a "passbook" savings account, where transactions were so infrequent that the bank recorded them directly in the patron's copy of the passbook. Over the years, increasing travel and nationwide communications led to the ubiquitous use of inter-bank money transfers, mostly in the form of the check. The accounts that checks typically drew on—checking accounts—were made for convenience and ease of access. You might deposit your entire paycheck into an account—it might even be sent there automatically—and then when you needed a little walking around money, you would withdraw cash by the assistance of a teller. By the time I was a banked consumer, even the teller was mostly gone. Today, we get our cash from machines so that it can be deposited into other machines.

Cash handling is fraught with peril. Bills are fairly small and easy to hide, and yet quite valuable. Automation in the banking world first focused on solving this problem, of reliable and secure cash handling within the bank branch. The primary measure against theft by insiders was that the theft would be discovered, as a result of the careful bookkeeping that typifies banks. But, well, that bookkeeping was surprisingly labor-intensive in even the bank of the 1950s.

The way I see it, few parts of American life are as quintessentially American as buying gas. We love our cars, we love our oil, and an industry about as old as automobiles themselves has developed a highly consistent, fully automated, and fairly user friendly system for filling the former with the latter.

I grew up in Oregon. While these rules have since been relaxed, many know Oregon for its long identity as one of two states where you cannot pump your own gas (the other being New Jersey). Instead, an attendant, employee of the gas station, operates the equipment. Like Portland's lingering indoor gas station, Oregon's favor for "full-service" is a holdover. It makes sense, of course, that all gas stations used to be full-service.

The front part of a gas station, where the pumps are and where you pull up your car, is called the Forecourt. The practicalities of selling gasoline, namely that it is a liquid sold by volume, make the forecourt more complex than you might realize. It's a set of devices that many of us interact with on a regular basis, but we rarely think about the sheer number of moving parts and long-running need for digital communications. Hey, that latter part sounds interesting, doesn't it?

Electric vehicles are catching on in the US. My personal taste in vehicles tends towards "old" and "cheap," but EVs have been on the market for long enough that they now come in that variety. Since my daily driver is an EV, I don't pay my dues at the Circle K nearly as often as I used to. One of the odd little details of EVs is the complexity hidden in the charging system or "EVSE," which requires digital communications with the vehicle for protection reasons. As consumers across the country install EVSE in their garages, we're all getting more familiar with these devices and their price tags. We might forget that, well, handling a fluid takes a lot of equipment as well... we just don't think about it, having shifted the whole problem to a large industry of loosely supervised hazardous chemical handling facilities.