The world's biggest laser is here. And scientists hope it can squish hydrogen atoms together.

The National Ignition Facility (NIF) at Lawrence Livermore National Labs this week unveiled a stadium-sized laser with 192 extremely-high powered beams. The beams can be focused onto a spot about a half a millimeter in diameter in a target chamber.

If the energy can be delivered onto a fuel pellet made up hydrogen isotopes, it can conceivably cause the atoms to fuse into a form of helium, and thereby deliver more power than the lasers consume. Fusion is safer than nuclear fission, the basis of current nuclear plants, because it doesn't generate the same waste product. Fusion also can't result in a chain reaction.

The lab hopes to demonstrate that it can work in 2010 or 2011.

But it's a big if. Skeptics have derided nuclear fusion for years, and noted the lengthy delays on fusion projects. Fusion reactions take place in rarified environments at 100 million degrees Celsius.

"When I was at MIT in 1971, it was 25 years away. It is still 25 years away," Frank Bowman, CEO of the Nuclear Energy Institute and a retired Admiral, told me in 2007.

A small group of startups – General Fusion, Tri-Alpha Energy – have received venture funds in the past few years to see if fusion power will be possible on a commercial scale. General Fusion hopes to one day build 50-megawatt plants for $100 million. General Fusion investors have said that the practicality of fusion could be proven in three to five years. Fusion plants would produ ce no carbon emissions and wouldn't come with the environmental hazards of nuclear fission plants.  Still, there's that problem of actually getting this stuff to work outside of the rarefied atmosphere of a lab.

Last year, MIT scientists showed how radio waves could be used to sustain the plasma needed for fusion reactions (see Will Radio Make Fusion Power Possible?).

Earlier this month, NIF became the first fusion laser in the world to break the megajoule barrier (a megajoule is the energy consumed by 10,000 100-watt light bulbs in one second) by delivering 1.1 million joules of ultraviolet energy to the center of its target chamber -- more than 25 times more energy than the previous record-holder.

Nuclear fission, of course, is making a comeback at the moment. Several companies are expected to file papers to build 31 nuclear reactors in the U.S. Startups like TerraPower and Hyperion Power Generation (Hyperion depends in part on national lab tech) are working on small nuclear reactors that can be sealed and buried.