I’m not certain what an “antigravity car” is, but half a century ago some terrifically smart people predicted that Americans might be driving them by now.

Yet here we are, nearly two decades into the new millennium, and most of us are still getting around in the same old way, by exploding a mixture of gasoline and air to turn wheels.

The chief challenge of the automobile engineers these days is to figure out how to make cars that drive themselves. Anyway we’re too preoccupied with controlling our Bluetooth connectivity to worry about anything as stubborn as gravity. And those equations, with all the letters and fractions, can give you a headache.

We haven’t always been so lacking in initiative.

Among those who in 1968 pondered the possibility that antigravity cars would be plying our highways (or, perhaps, skyways) by 2018 was D.G. Brennan, a mathematician and expert in national security issues.

Brennan wrote one of 13 chapters in the 1968 book “Toward The Year 2018,” edited by the Foreign Policy Association.

I acquired this book in 2011 and I first wrote about it later that year.

The volume has languished in one of my bookshelves ever since, but what with its titular year being well under way, I figured I would have another look through it.

The book’s concept is straightforward — Brennan and a dozen other writers offered their educated opinions (very educated, I should say; most of the authors had at least one advanced degree) on these topics: weaponry, space, transportation, communication, weather, educational technology, behavioral technology, computer technology, energy, food, population, economics and oceanography.

In his chapter Brennan confronted the subject of weaponry.

Then as now that’s a field where technology is vital. In many instances Brennan’s descriptions don’t sound especially dated — at least not to a layperson such as myself who doesn’t know a joule from a julep.

His ruminations about the importance of improving battery performance, for instance, seem utterly contemporary even though he writes about military applications rather than building electric cars that can cross big western states without plugging in.

In other paragraphs, though, it’s impossible to not notice how vastly the world has changed in the past 50 years.

Brennan felt it necessary to put quotation marks around the “chip” in computer chip, for instance — today, of course, a second-grader doesn’t need much context to know when she’s reading about chips made from silicon rather than potatoes.

Hamstrung though he might have been by lacking half a century’s worth of hindsight, it requires no great leap to believe that Brennan, who died in 1980, would see the advent of the smartphone as predictable.

He writes, in describing how quickly computer technology was progressing even in the 1960s, that by 2018 “one would expect to find computers with a capacity on the general order of the human brain (but much faster) that could be carried in a shoe box, or perhaps in one’s pocket.”

What Brennan would have made of selfies I can’t say, although he seems to have been quite a serious fellow, working as a consultant for, among other entities not known for flights of fancy, the U.S. Departments of State and Defense.

Several other authors also wrote with prescience about the much greater role that computers would play by 2018, including making information more accessible to more people than ever before.

In the chapter titled “educational technology,” Anthony G. Oettinger, a professor of applied mathematics at Harvard University, might well have been describing the internet when he questioned the idea that when it comes to information, quantity is more valuable than quality.

“Many people — diplomats and policy-makers are not immune — suffer from the delusion that any piece of data is valuable in itself, that more and better data mean more and better information, and that better information means better decisions,” Oettinger wrote. “The notion that one can or should acquire every bit of information relevant to a particular issue is surely a delusion. By opening wide the floodgates of information, technology has created, as it always does, both an opportunity and a threat.”

Suffice it to say that Oettinger, who is 88, probably wasn’t surprised that the Net birthed YouTube as well as online encyclopedias.

The most strikingly discordant aspect of “Toward The Year 2018” is its authors’ optimism about technology and its ability to improve our lives.

I don’t mean to imply that the writers are either pollyannas or propagandists. They all, as Oettinger does in describing the potential ills of an information revolution, acknowledge that scientific breakthroughs aren’t likely to be wholly benevolent.

Yet many of the chapters still bear the hopeful nature of that era, a belief in technology that persisted even though the “greatest” achievement of the preceding quarter century was building bombs that could obliterate entire cities.

Multiple chapters include predictions about the prevalence of nuclear power in 2018, a prediction that, at least in the U.S., has proved to be wildly inaccurate.

This is a pity. The increasing effects of climate change over the past 50 years have coincided with dramatic improvements in the safety of nuclear power, yet the irrational abhorrence for fission has stymied what could have been a significant reduction in how much carbon dioxide we’re belching into the atmosphere.

Still and all, some of the authors’ ideas about the possible uses of nuclear power seem to me more science fiction fantastical than realistic.

Roger Revelle, an oceanographer and chairman of the U.S. National Committee for the International Biological Program, wrote the chapter on oceanography.

His suggestion for making California’s beaches more attractive to visitors would, I suspect, cause considerable consternation among many in that state today.

Revelle wrote: “Off the coast of California, most of the water is too cold to swim in. It may be possible to warm it up, particularly in the near-shore zone, by using waste heat from the large nuclear power plants of the future.”

That future, it turns out, hasn’t arrived.

California has only one nuclear power plant operating today — Diablo Canyon, on the Pacific shore in San Luis Obispo County — and although its reactors are cooled by seawater I have found no reference to its waste heat being used to keep beachgoers’ toes from going numb.

Indeed, it appears that we’re moving away from rather than toward the future that Revelle foresaw. Pacific Gas & Electric of San Francisco announced in January that it intends to close Diablo Canyon’s two reactors when their federal licenses expire, one in 2024 and the other in 2025.

Revelle’s interest in nuclear power was not limited to his work in oceanography, either. In 1957 he co-authored a scientific paper that all but introduced a term which today is as common as corn flakes — “the greenhouse effect.”

Revelle, who died in 1991, recognized that burning fossil fuels was a major contributor to the increasing concentration of carbon dioxide in the atmosphere. And although climate change in 1968 was mainly of interest to a relative handful of scientists, Revelle reached the logical conclusion that nuclear power, which doesn’t spew carbon into the atmosphere, would inevitably produce a bigger share of America’s, and the world’s, electricity in the coming decades.

It strikes me as passing strange that 50 years later, when a lot of people outside science consider climate change a proximate threat to the Earth, nuclear power still seems to be defined more by Hollywood (see: “The China Syndrome”) than by the dispassionate science that Revelle and his colleagues practiced.

Such is the nature, I suppose, of predicting the future based on intellect and reason rather than emotion.

Jayson Jacoby is editor of the Baker City Herald.