NIF is expected to ramp up power gradually in a series of experiments over the next year, culminating at a power level in 2010 to achieve what scientists call “fusion ignition”: enough heat and pressure to fuse hydrogen atoms in a tiny cylindrical target so that more energy is released than is generated by the laser beams themselves.

That is what happens when a hydrogen bomb explodes and inside the sun, at its center. It’s also what scientists would one day like to achieve on a continuing basis to produce a clean, safe form of energy by fusing atoms instead of splits them apart.