From the start of the Industrial Age, "bigger is better" has been the guiding principle of development. This ethos spurred the evolution of little village shops into skyscrapers, one-horse carriages into 250-horsepower autos, and wind-powered schooners into supertankers. But in recent decades, that trend has undergone an astonishing reversal; until today, at the start of the 21st century, the most exciting advances in technology are being developed on a scale of trillionths of a meter and under.

At this level, known as the nanoscale, all materials, from biological to inorganic to electronic, interface in a similar manner. The molecule-to-molecule control afforded by nanoscale technologies has made a broad array of cross-disciplinary experiments possible. Microscopic electrodes are being attached to individual neurons in brain research, while protein molecules are amplifying signals for exquisitely sensitive nanoelectronic systems. "Previously separate fields are coming together, employing similar transforming tools and applying comparable concepts," explains William Sims Bainbridge of the National Science Foundation (NSF). Add to this mix the information-sharing and processing power of modern computers, and "convergence" becomes the vehicle of a new revolution in human technological advancement.

Since 2001, when the National Science Foundation sponsored a conference on the societal implications of nanotechnology, there have been regular conferences to discuss the social, economic, and societal implications of converging technologies. Government interest in this topic should come as no surprise, notes Mihail C. Roco of the NSF; technological convergence "has become one of the main drivers for technological and economic change, as well as industrial competition."

The fourth such meeting, a conference titled Converging Technologies for Improving Human Performance, was held in Hawaii in February 2005. The meeting was the impetus behind volume 1093 of the Annals of the New York Academy of Sciences, Progress in Convergence: Technologies for Human Wellbeing, edited by Bainbridge and Roco. It aims to chart recent progress in convergence, identify opportunities for future progress, and anticipate the social implications of these emerging applications. The four primary technologies that Roco and Bainbridge consider to be converging are nanotechnology, biotechnology, information technology, and cognitive sciences, known collectively as NBIC.

Biological systems are a logical template for convergent technology studies. Organisms can produce a dizzying range of materials with amazing properties, often using elements that self-assemble into intricate, nanoscale, highly organized structures. Osamu Takai of Nagoya University, Japan, discusses how convergent technology is making it possible for humans to identify the source of a natural material's unique qualities, and mimic these properties with synthetic materials. For example, the lotus leaf's superior water-repelling abilities are due to the precisely controlled roughness of its surface. This nanoscale roughness can be emulated with silicon oxide films. Made up of self-assembled monolayers of organosilane, these films can be applied to many surfaces in precise patterns with the photolithography techniques used to manufacture computer chips.

Studies of the small are opening up new opportunities in many fields.

By modulating the reactivity, hydrophobicity, and electrical properties of a surface, this same technology can, for example, enable the growth of cultured cells into three-dimensional tissues. On an ultra-hydrophobic surface, droplets of cell culture medium tend to form perfect spheres. Any cells within those droplets will then develop in three dimensions instead of growing into a flat sheet.

Studies of the small are also opening up new areas of inquiry in a field better known for landscape-scale analyses: the geosciences. Soils are essentially large aggregations of particles which interface with water, bacteria, and even the air at the nanoscale, states Michael F. Hochella, Jr., of Virginia Tech. For example, the firmness with which the proteins in a bacterial cell wall adhere to substrates such as soils can affect how far and fast these microbes are transported through the landscape. Understanding how to alter the binding capabilities of these proteins could help slow cases of contamination in wells, aquifers, and even agricultural fields. Toxic metal contamination from mine tailings also appears to be fundamentally a nanoscale phenomenon. Metal molecules become bound to nanoparticles in soil, then spread throughout the environment via erosion, runoff, and dust. In fact, the atmosphere can transport the tiniest dust particles from industrial pollution, agricultural areas, and arid lands across entire ocean basins, affecting cloud formation and how easily the earth warms and cools.

Scientists will need a unique set of equipment to study the alien environment of the nanoscale. Jia Ming Chen and Chih-Ming Ho of the University of California, Los Angeles, describe several innovative ways to work with tiny objects, including a superlens device that can overcome the diffraction noise of light waves and image objects at below-micrometer scales. Newly developed optoelectronic tweezers are both precise and gentle enough to manipulate individual live cells using electric fields patterned on a photoconductive surface. Integrating these and other nanoscale tools could accelerate the development of additional nanoscale technologies. For example, Chen, Ho, and colleagues are developing a self-contained silicon chip that uses a combination of microfluidics and optical sensors to screen for liver cancer without the assistance of bulky and expensive lab equipment.

Sharing ideas and tools across otherwise isolated disciplines is yet another form of convergence. The Internet is one technology that is already widely available. Bruce Herr and his colleagues at Indiana University report their development of a computerized format for disseminating research tools. Researchers frequently write custom software to perform specialized tasks. But in fact, what many scientists use computers to do isn't so unique—the need to acquire, process, manage, and manipulate large datasets is common to many types of research. A computer network cyberinfrastructure called CIShell should give scientists an easy way to share computing resources, saving them from having to reinvent these virtual wheels. An open-source specification, CIShell could help scientists integrate and use data sets, algorithms, programming tools, and other computing approaches via a Web interface, helping to advance science even faster.

Convergence may be a particular boon to people with disabilities by making assistive devices smaller and more powerful than ever. Anders Sandberg and Nick Bostrom of Oxford University describe devices that interface directly with the brain via electrodes or cochlear implants. These devices might help paralyzed people communicate with the outside world or help disabled people operate prostheses. Meanwhile, new attention- and memory-enhancing drugs, along with drug delivery methods that can be localized to certain parts of the brain, and electrical brain stimulation techniques, may help people rise above their current cognitive capabilities. The ethics of these and other NBIC modifications are discussed by several researchers later in the volume.

Computers mounted on eyeglass frames or clothing could help improve the social functioning of people with autism, report Rana El Kaliouby and colleagues at the Massachusetts Institute of Technology. People with this disorder have difficulty recognizing and understanding the moods and state of mind of others. Wearable computers could give people with autism an inobtrusive, portable means to interpret their own expressions, tone of voice, or even stress level in order to help them learn more appropriate responses. Devices aimed at others may be even more useful for autistic people, but they raise concerns about privacy.

The navigation problems of people with both cognitive disabilities and blindness could be ameliorated by a technology being developed by Lin Liao and colleagues at the University of Washington. The system is able to learn the personal routes of users using GPS data, and can identify significant sites such as home, work, the grocery store, and bus stops; infer destinations; and recognize situations in which the user makes mistakes, such as taking a wrong turn or catching the wrong bus. The same system could be used to provide information such as the schedules for current buses or to automatically turn off a cell phone when the user is at a meeting.

The products of convergence research are already leading us into uncharted ethical and social waters. Professional sports lies at the center of this storm. In recent years, professional baseball, the Tour de France, and the Olympics have all been wracked by controversy over the use of performance-enhancing drugs. Yet athletes seeking advantages through technology is nothing new. Andy Miah of the University of Paisley reminds us that athletes have always sought equipment engineered to help them throw farther, hit harder, and run faster. Meanwhile, body modifications resulting from LASIK surgery and hypoxic chamber use, have failed to elicit the same condemnation as steroids. As personal enhancements become more widely available, the rationale behind doping bans may lose meaning, Miah notes.

Convergence research is already leading us into uncharted ethical and social waters.

Some resistance to enhancement technologies is due to the idea that "doped" athletes would have an unfair advantage over their "clean" competitors. But detractors would do well to remember, writes Julian Savulescu of Oxford University, that human enhancement technologies also can be used to reduce inequality, injustice, and unfairness, as long as the social institutions that distribute them protect those who are least well off.

A great deal of federal funding is being spent to develop convergent technologies. Yet this burgeoning area of research, which has the potential to alter human nature every bit as profoundly as biotechnology has since the 1980s, has failed to capture the interest of the public. Nigel M. de S. Cameron of the Illinois Institute of Technology warns that this lack of interest could ultimately be harmful to further expansion of the field. He cites the rejection of bioengineered "frankenfoods" in Europe due to lack of public debate as an example. Finally, Alan S. Ziegler of the Institute of New Dimensions advises against being too cautious about making developments such as nanotechnology available. He writes that the synergistic effects of convergent technologies, such as new health treatments, are likely to be unpredictable. These technologies will have the potential for great good for many people as well as great harm to an unpredictable few. Making a revolutionary health treatment available now, and compensating those who might be harmed along the way, he argues, would make converging technologies available while keeping society safe along the way.