Thermodynamics - this sort of applies, right? Yeah, yeah, it's never going to happen...maybe. In California, a lab is betting with $3.5bn that it will - and soon. They're well on their way building the structure and what not. This article explains it in detail: http://www.newsweek.com/id/222792
I'd like to see some actual numbers regarding whether or not their massive laser can actually trigger ignition. I'll post if I find some.