Emerging technologies are technologies in their infancy or adolescence that some observers consider likely candidates for partially or completely replacing legacy technologies. For instance, some futurists believe that nuclear power -- both fusion and fission -- and renewables will entirely replace the burning of fossil fuels. This would be a highly appealing outcome, as it would provide us with electricity without contributing to global warming. It should be noted that some emerging technologies and their impacts are more speculative than others, and have differing degrees of support among experts. For instance, futurists in the 1950s predicted flying cars and Moon cities by the year 2000, but these never happened.
Major emerging technologies can be put into roughly six categories: energy technologies, transportation, information technology, biotechnology, robotics, and material science. The most talked-about are energy technologies, so we'll start with those first.
For decades, portions of the Western world have realized that burning fossil fuels won't work in the long term. Therefore, millions of man-hours have been put into researching alternative sources of energy, but to date, these only account for 10% of the global energy budget. The best provider of alternative energy is nuclear power, followed by the burning of biomass. Emerging technologies which may revolutionize global energy production and storage include cheap and efficient solar cells, nuclear fusion, production of biofuels by synthetic microbes, and nanowire batteries.
Another target zone for emerging technologies is transportation. First on the list, of course, would be the flying car, but there are many transportation technologies which could have a major impact on mankind. Cheap space access would be one, likely via a space elevator, Space Blimp, or skyhook of some sort. More mundanely, electric cars would be nice, though without widespread post-fossil-fuel methods of power generation, they would still consume coal or gas, albeit indirectly. For more advanced airplanes, scramjets could be revolutionary -- these air-breathing engines could allow a plane to travel from New York to Sydney in three hours.
Another possible incubation ground for emerging technologies is information technology. The Internet has obviously revolutionized how the developed world works and lives in the last couple decades, and continues to do so. Every investor is looking for the next Google, and it seems like only a matter of time before such a company emerges, championing what is now an emerging technology. Possibilities include Artificial Intelligence, machine translation, machine vision, the Semantic Web, 3D optical data storage, wearable computing, 3D displays, 3D printing, and many others.
Other domains that are seeing emerging technologies include biotech, robotics, and materials science. In biotech, movement towards personal genomics and synthetic life is happening. In robotics, it looks like the long-awaited home robotics revolution might actually happen, while in materials science, scientists are developing materials stronger and smarter than before, like fullerenes and metamaterials. The future looks bright, but it is hard to predict what will live up to the hype and what will be nothing but a disappointment.