Seven countries signed an agreement in Brussels last week (May 24) to launch construction of the multibillion dollar International Thermonuclear Experimental Reactor (ITER) in southern France. The largest fusion-energy experiment ever conducted, ITER is the culmination of years of research by scores of scientists, and is poised to answer long-standing questions about the real-world viability of fusion energy. The United States, China, the European Union, India, Japan, the Republic of Korea and the Russian Federation are joint sponsors of the project, which will experimentally generate up to 500 million watts of energy.

Fusion energy describes the energy that is released when atomic particles "fuse" together to form heavier particles. The process is fundamental to our universe, fueling both the sun and the stars. Here on Earth, physicists have tried to harness the energy potential of nuclear fusion by working with plasma, essentially a collection of particles, such as hydrogen nuclei, that carry electric charge. Because hydrogen can be easily extracted from seawater - a cheap and abundant resource - scientists have been tantalized by the prospect of plasma one day serving as an inexhaustible fuel.