[GOPJ]

What they demonstrated was the conversion of photons into other particles. Particle-antiparticle annihilation (with intermediate steps to preserve energy and momentum) resulting in baryonic (particles with rest mass) conversion to photons is old hat. They went the other way and converted "massless" (having no rest mass) particles, photons, into "massive" (having rest mass) particles, W- bosons.

Nice to have that cleared up...

[Lonesome in Massachussets]

Nice to have that cleared up...

I was worried about that. Maybe I should have said that conversion of stuff into light had already been demonstrated. In this experiment they converted light into stuff.

There may be a Second Law (of Thermodynamics, of course) thing going on. Stuff has less entropy than light. It's much, much easier to start a fire, than reassemble the ash, heat, and light back into their prior form.