Albert Einstein told us that the line between matter and energy is a fuzzy one. Energy can be produced by either splitting or combining atoms—processes known as fission and fusion respectively.
Nuclear fission releases harmful radiation and produces large amounts of radioactive material, which can remain active for thousands of years and can destroy entire ecosystems if leaked.
There is also concern that nuclear material could be used in weapons. Currently, most nuclear power plants use fission, as fusion requires tremendous amounts of energy to produce and maintain the necessary high temperatures.
But a natural phenomenon known as sonoluminescence might one day provide a means of duplicating the power of the stars—which are themselves just giant nuclear fusion reactors -- in a beaker of liquid. Sonoluminescence refers to the flash of light produced when special liquids are struck by high- energy sound waves. The sound waves rip through the liquid and produce tiny bubbles that rapidly expand and then violently collapse. Light is produced in the process, but more importantly, the insides of the imploding bubbles reach extremely high temperatures and pressures -- enough, some scientists speculate, for nuclear fusion to occur.
Scientists are also experimenting with methods to create controlled nuclear fusion by accelerating "heavy" hydrogen ions in a powerful electric field.