Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100

a ten-story building the size of three football fields, with 192 giant laser beams being fired down a long tunnel. It is the largest laser system in the world, delivering sixty times more energy than any previous one.
    After these laser beams are fired down this long tunnel, they eventually hit an array of mirrors that focus each beam onto a tiny pinhead-size target, consisting of deuterium and tritium (two isotopes of hydrogen). Incredibly, 500 trillion watts of laser power are focused onto a tiny pellet that is barely visible to the naked eye, scorching it to 100 million degrees, much hotter than the center of the sun. (The energy of that colossal pulse is equivalent to the output of half a million nuclear power plants in a brief instant.) The surface of this microscopic pellet is quickly vaporized, which unleashes a shock wave that collapses the pellet and unleashes the power of fusion.
    It was completed in 2009, and is currently undergoing tests. If all goes well, it may be the first machine to create as much energy as it consumes. Although this machine is not designed to produce commercial electrical power, it is designed to show that laser beams can be focused to heat hydrogen-rich materials and produce net energy.
    I talked to one of the directors of the NIF facility, Edward Moses, about his hopes and dreams for his project. Wearing a hard hat, he looked more like a construction worker than a top nuclear physicist in charge of the largest laser lab in the world. He admitted to me that in the past there have been numerous false starts. But this, he believed, was the real thing: he and histeam were about to realize an important achievement, one that will enter the history books, the first to peacefully capture the power of the sun on earth. Talking to him, you realize how projects like NIF are kept alive by the passion and energy of their true believers. He savored the day, he told me, when he could invite the president of the United States to this laboratory to announce that history had just been made.
    But from the beginning, NIF got off to a bad start. (Even strange things have happened, such as when the previous associate director of NIF, E. Michael Campbell, was forced to resign in 1999 when it was revealed that he lied about completing a Ph.D. at Princeton.) Then the completion date, originally set for 2003, began to slip. Costs ballooned, from $1 billion to $4 billion. It was finally finished in March 2009, six years late.
    The devil, they say, is in the details. In laser fusion, for example, these 192 laser beams have to hit the surface of a tiny pellet with utmost precision, so that it implodes evenly. The beams must hit this tiny target to within 30 trillionths of a second of one another. The slightest misalignment of the laser beams or irregularity of the pellet means that the pellet will heat unsymmetrically, causing it to blow out to one side rather than implode spherically.
    If the pellet is irregular by more than 50 nanometers (or about 150 atoms), the pellet will also fail to implode evenly. (That is like trying to throw a baseball within the strike zone from a distance of 350 miles.) So alignment of the laser beams and evenness of the pellet are the main problems facing laser fusion.
    In addition to NIF, the European Union is backing its own version of laser fusion. The reactor will be built at the High Power Laser Energy Research Facility (HiPER), and it is smaller but perhaps more efficient than NIF. Construction for HiPER starts in 2011.
    The hopes of many ride on NIF. However, if laser fusion does not work as expected, there is another, even more advanced proposal for controlled fusion: putting the sun in a bottle.
    ITER—FUSION IN A MAGNETIC FIELD
    Yet another design is being exploited in France. The International Thermonuclear Experimental Reactor (ITER) uses huge magnetic fields to containhot hydrogen gas. Instead of using lasers to instantly collapse a tiny pellet of hydrogen-rich material, ITER uses a magnetic field to slowly compress hydrogen gas. The machine looks very much like a huge hollow doughnut made of steel, with magnetic coils surrounding the hole of the doughnut. The magnetic field keeps the hydrogen gas inside the doughnut-shaped chamber from escaping. Then an electrical current is sent surging through the gas, heating it. The combination of squeezing the gas with the magnetic field and sending a current surging through it causes the gas to heat up to many millions of