Look at your car sitting there in the driveway—sad, squat, all four tires on the pavement. You should feel sorry for your car for the same reason that you should feel sorry for yourself: You are both flightless. Optimistic drivers of the past imagined a future in which the stubby tail fins of their cars morphed into broad wings. According to the car companies presenting at the World's Fair of 1939, your driveway was destined to become a runway, the highway a skyway, and the only speed limit the speed of sound.

The first attempts at creating flying cars were fairly simple—install an airplane engine and two wings on a regular car. The first attempts were also disastrous. Henry Ford's "sky flivver" flew in 1928, but production was nixed after an unlucky pilot died in a crash. In 1956, Moulton Taylor, an engineer who earlier had helped develop the cruise missile, unveiled the Aerocar. The little yellow Aerocar could leap from the highway at 55 miles per hour and cruise up to 100 mph at around 12,000 feet with a range of up to 300 miles. The Aerocar worked fine conceptually, but it was too impractical for everyday use—a business deal for full-scale production fell through in the early 1970s. The only remaining Aerocar prototype was purchased by a fan who saw it advertised in the classifieds.

If you are averse to purchasing dangerous relics listed in obscure newspaper ads and you still want to acquire a flying car, the solution may be to let NASA take care of it. That's right, NASA gave us gooey foam pillows, dehydrated ice cream, and those shiny space blankets, and it may yet fork over the flying car. NASA scientists working on the Small Aircraft Transportation System (SATS) project are making inroads on the two main problems holding back personal air travel on a massive, nationwide scale: midair collisions and complicated piloting mechanisms.

NASA eschews the term "flying car," preferring "personal air vehicle" instead. Nevertheless, NASA has imagined flying cars that would humiliate George Jetson. Until their vehicle program was eliminated in 2005, the folks at Langley Research Center planned to roll out three prototypes in sequence: a small prop plane that would tuck its wings in on the highway (it shouldn't cost any more than a Mercedes-Benz); a two-seater with rear-propeller drive; and, for tight parking spots, one capable of vertical takeoff. Merely providing the vehicles would not be enough, however. If everyday people are to use them, scientists must know how to track thousands of these car-planes. And knowing is half the battle.

Collision-deterring navigation systems are key to transforming highways into skyways. Personal air vehicles will use GPS and cell phone technology to automatically broadcast information about location and speed to ground-based towers. From the ground, an automated computer system will update the flight path of every sky vehicle and provide instant directions—automatically avoiding collisions and minimizing flight time. Meanwhile, onboard sensors will detect nearby trees, buildings, and power lines. And the jackpot bonus item for the sky-car consumer: For most of the flight the human "driver" can take care of anything besides flying, like eating a whole bag of potato chips.

NASA's dream cars may be exciting (and legitimate), but they aren't available to the public right this second. So turn your attention to the Moller M400 Skycar—a partially tested prototype offered in the 2005 Neiman Marcus gift catalog. Paul Moller, a former engineering professor at the University of California at Davis, has spent all of his money and more than 40 years trying to build a flying car. The current model is a cherry-red coupe that looks as though it should be dogfighting TIE fighters outside the Death Star. The futuristic Skycar has four seats (carrying up to 750 pounds), a maximum airspeed of 375 mph, and a range of about 750 miles. On the ground, the Skycar should travel a dinky 30 to 35 mph, just fast enough to get to an empty parking lot and stun everyone with a sweet vertical takeoff. Prototypes like the Skycar have been on the verge of full-scale production for almost a century, though, and it may be another hundred years before you can score that most badass symbol of the space age, the flying car.

Yesteryear's dinner of tomorrow was designed to feed the spacefaring denizens of an overpopulated planet. It was cheap, it was synthetic, and it was so completely off the mark as to be almost wholly inconceivable to us now. These days people expect real food from the ground, preferably without any genetic splicing. But the food predictions of yesterday are as tantalizing as ever. What's more American than an apple-pie pill?

As a rule, future food does not come from the ground. In the best-case scenario it comes from lush hydroponic gardens, but it's much more likely to come from a factory, a tube, or a vat. In addition, future fodder never looks like food, either; it looks like a piece of plastic, a splash of corn-syrupy liquid, or—best of all—a tempting little white pill.

The space program kick-started a food revolution. Kids were fascinated with how food got into the astronauts (and how it got back out). Space travelers have serious dietary restrictions: Food has to be as light as possible because every ounce counts on liftoff, and gooey foods are preferred, as renegade crumbs can damage delicate machinery. As a result, early astronauts had to suck food out of tubes, toss back vitamin pills, and generally have a culinarily bad time. In the early 1960s, astronauts on the Mercury space missions sucked applesauce out of aluminum tubes. Later, the menu was expanded to include "food powder," freeze-dried food that had to be squirted with cold water and then sucked through a straw. By 1965, Gemini astronauts were subjected to Tang, which has the limited advantage of making water taste less like water. Luckily, by 1973, astronauts on the Skylab space station had a luxurious meal-preparation area and a menu with over 72 items.

But seriously, where are the food pills? The idea is theoretically possible, but like most "technological food," it's not commercially viable. Thankfully, the Combat Feeding Directorate (called Natick, after its location) is working ceaselessly to keep U.S. soldiers well fed—and the soldiers have little say in the matter. A decade ago Natick introduced MREs ("meals ready to eat")—individually packaged, self-heating food pouches. Its most recent innovation is the compressed meal (CM). A CM is one-third the size and weight of an MRE but has the same number of calories. At this rate, the food pill may be on the menu soon. Under the far-reaching metabolic-dominance program, the Defense Advanced Research Projects Agency (DARPA) is soliciting proposals for a pill that will allow soldiers to operate at peak performance during prolonged periods of starvation. Meanwhile, Natick is working on a transdermal nutrient patch that will enable soldiers to go without food for up to three days.

Although military grunts must eat what they are given, the general public seems to hate the idea of nonnatural food sources. For some reason, a bloody hunk of cow meat is more appetizing to most people than a shivering plate teeming with microbial life. Go figure. Nevertheless, many technological foods (including food pills) are either available or under development. For now, you can find the closest food pill equivalent at your local 7-Eleven—go out and buy a HOOAH! brand energy bar; the bars were developed by the Pentagon and have been shown to delay time to exhaustion by about 20 percent.

A lot of promises are made in the bedroom and on the campaign trail, but the biggest, most important promises are made in tiny print on the last few pages of comic books—like the promise of glasses that let you see through things. For a modest price these advertisements guarantee the Superman-like ability to see through walls; but honestly, X-ray spectacles were really all about seeing through clothes. The "scientific marvel of the century" offered in comic books may be a gimmick, but modern defense contractors are not playing around.

Visible light insists on bouncing off even the flimsiest nontransparent objects. An X-ray is like visible light except that it has more energy. High-energy photons (which are invisible to our eyes) tend to penetrate farther into objects before they bounce off—or they can go all the way through. To develop X-ray spectacles, the trick is to use light with just enough power to penetrate clothing but not enough to penetrate skin. Because let's face it, no matter what the fashion magazines say, walking skeletons are just not that sexy.

The need for better airport security led to the development of a new backscatter machine that uses low-power X-rays with just the right finesse—they penetrate clothing but not skin. Specifically, the machine emits and measures the position of X-rays that "scatter back" from a person and generate a photograph-quality image. The process is sometimes referred to by the vaguely disgusting term "backscatting." Very dense objects (like guns) show up dark, medium-dense objects (like skin) come out grayscale, and not-very-dense objects (like clothes) don't show up at all. To summarize, it's a magical machine that spits out naked images of fully clothed people. But a backscatter machine won't fit on your face; it's the size of a refrigerator and takes about eight seconds to scan a person standing about eight inches away.

When X-ray eyes leave the realm of gimmicks and enter the local airport, privacy becomes an issue. Who should wield such awesome power? Though backscatter devices are commonly used in prisons, diamond mines, and customs searches, introducing the machines to airports has been a tough sell. Critics warn against bombarding children and adults with X-rays, even low-power X-rays. Meanwhile, the CEO of an X-ray machine company cheerfully reports that radiation levels are similar to that of good, clean sunlight. The American Civil Liberties Union describes the process as a "virtual strip search." Travelers in the United Kingdom, however, are unfazed; virtual strip search machines have been used at London's Heathrow Airport for years.

Gawking at naked people is always good fun, but what about using your abilities for the forces of good? Superman used his X-ray vision to see through walls in an endless, obsessive search for truth and justice. Now lowly humans can do the same using the Radar Scope. Research funded by DARPA recently produced the device, which is the size of a telephone handset and can sense human beings through up to 12 inches of concrete. The "through-wall personnel detector" uses radar to sense movements as small as breathing up to 50 feet into the next room. Put simply, it is a motion detector that works through walls.

Whether your goal is to see through walls or bikinis, the technology is here. And unlike the swirly sunglasses that disappointed so many of us, these gadgets actually work. Finally, humankind has mastered the power of light and put it to a noble purpose. For around a thousand dollars, you can buy a Radar Scope and dominate future games of hide-and-seek, but at a reported cost of six figures, backscatter portals are likely to be out of the reach of most comic-book readers.

Since the beginning of time, children have performed all the duties of a so-called smart home: grabbing beers from fridges, changing television channels, and taking verbal abuse for problems they don't understand and probably didn't cause. Considering that children have been around forever, it is only reasonable to expect that a better technology exists by now. Certainly, we should all be living in robotic houses that act as conscious, living servants to meet our every need and desire.

Right now, "smart home" technology is available off the shelf; home automation enthusiasts have access to all kinds of gadgets that can make life simpler (and more complicated). The key goal for home automation is to give the occupant total control over the house from anywhere. Most home automation devices require a central personal computer to provide control and to run programs. For instance, X10 modules plug into the wall and then communicate with a home computer, letting a person turn on and off lights and appliances via a Web site. There are quite a few sensors, such as cameras, motion detectors, or water leak detectors, that can be used to monitor who is in your driveway, trigger exterior lights when people approach, or constantly check for broken water pipes. Meanwhile, effectors can be used to water plants automatically, remotely raise and lower blinds, or feed your pets. Anyone can create the ultimate remote-control house—the only limit is your wallet.

Sadly, fetching your beer is not a priority for smart homes. Instead, the most promising application is to help elderly people live safely and independently. Smart homes are being designed to use simple sensors common to home security systems and advanced artificial intelligence in order to figure out what people are doing (activity recognition) and where they are (location estimation). The Georgia Tech Aware Home looks like a two-story house but is in reality a laboratory bristling with sensing equipment, including cameras in the ceiling, microphones in the walls, and invisible trip sensors in doorways. The Aware Home and other laboratories like it are the very first prototype smart homes that will help us all stay out of the nursing home someday.

If you are frightened by disembodied voices that emanate from speakers in the walls, then you may want to complement your smart home with a mobile robot. In an experiment with Nursebot (a trashcan-size wheeled robot designed to deliver medicine and reminders) at Carnegie Mellon University, researchers found that by using a laser range finder, a robotic home could correctly predict the paths that people commonly take so that mobile robots could learn to stay out of the way. Nursebot can use such knowledge to effectively cater to occupants. She even has grab bars so that elderly users can grab hold and stand up. Beat that, Rascal Scooter!

The death ray is the logical equivalent of a six-shooter for a hard-drinkin', hard-fightin' space cowboy. In early science fiction pulps, any adventurer worth his space boots carried an old-fashioned holster containing a high-fashion ray gun—and the more stylish the fins, the better. The hardware is now available for us to emulate our cosmic heroes.

Ray-gun-like weapons are quickly becoming commonplace. Preliminary weapons are nonlethal and have been used by happy-go-lucky military troops and police officers eager to teach new dance moves to protesters and rioters. Several classes of directed energy weapons, called nonkinetic weapons by military types, have met field trials and are coming into widespread use.

The Active Denial System, developed by the Pentagon, can aim and emit superhigh-frequency microwaves. When the millimeter-size wave pulses hit human skin, they heat the body's water to the point of pain. The burning sensation has been compared to touching a hundred-watt lightbulb but without the singed hair—the system is only playing with your nerve endings, not causing permanent damage. Currently, the weapon won't fit in your holster—soldiers have to mount them on top of Humvees.

Alternately, why not use a prototype "lightning gun" to harness the Zeus-like power of electricity? A host of new defense contractors have sprouted to help governments battle terrorists, and they supply a variety of hair-raising weapons. Companies like Ionatron and Xtreme Alternative Defense Systems have developed competing zap guns. Both weapons use pulsed lasers to create a conductive path in the air away from the gun's barrel and then use a simple Tesla coil to generate a painful bolt of electricity. Both rifles are the size of a briefcase, weigh 25 pounds, and can shoot electricity wildly at 12 feet or consistently at 4 feet. Occasionally, the flashing purple discharge kicks back and lashes the bejesus out of the poor guy holding the gun.

We have so far ignored the most compelling directed energy weapon of all—the laser blaster. Jedi Knights can apparently use light sabers to easily deflect laser bolts, but electrically driven solid-state laser weapons (preferred over their less-wieldy chemical-based cousins) are designed primarily to zap approaching missiles. Field-tested military prototypes are pushing 25 kilowatts of power, and research is under way on versions that can turn missiles into swiss cheese with 100 kilowatts of laser power (a million times more powerful than an everyday laser pointer).

Meanwhile, the General Atomics company has developed a prototype weapon, called the High Energy Liquid Laser Area Defense System (HELLADS). Precise details are classified, but the system purportedly combines two types of laser, liquid and solid-state, for a single über-powerful weapon. Unlike other liquid lasers, the HELLADS can fire a continuous beam without a large cooling system, and unlike solid-state lasers, the HELLADS produces a high-energy density that does not require pulsing the laser on and off. The whole system weighs 1,600 pounds and can fit into the space of a large refrigerator. The project goal is to eventually spit a 150-kilowatt beam clean through enemy missiles.

The big question, of course, is what is keeping a handheld laser blaster out of your pocket? The most noticeable obstacle is heat dissipation. Operational lasers are inefficient, converting only about 15 percent of electric power into laser, with the rest wasted in the form of extreme heat. More efficient diodes (the part that converts electricity to light) would lower heat output and shrink lasers so that they could hang jauntily on your hip. For now, though, you will have to be happy with mounting military lasers to your tactical ground vehicle (that's your Buick).

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This article is excerpted from Where's My Jetpack? A Guide to the Amazing Science Fiction Future That Never Arrived, to be published in April 2007. Copyright 2007 by Daniel H. Wilson, Ph.D. Printed by arrangement with Bloomsbury USA.