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Read more: 鈥�Tricks of the light: Nine fabulous photon spin-offs鈥�

Making photons is not exactly difficult. At their most basic, they are just packets of electromagnetic energy. Hit an atom with a photon of the right frequency, and the atom gains energy as it absorbs the photon; equally, if an atom has more energy than it is comfortable with, it will 鈥渄e-excite鈥� and emit a photon. Enclose atoms and excite them with light of just the right frequency, and you get out many more photons than you put in 鈥� the amplification process that is the basis of the laser.

Today, even a humble laser pointer produces something like 10¹⁶ photons each second. A suite of 192 lasers at the stadium-sized at the Lawrence Livermore Laboratory in California, currently in its testing phase, will concentrate 10³³ photons every second on a single spot. That should be enough to initiate a thermonuclear reaction and turn hydrogen into helium for fusion power.

Making photons seemingly from nothing is even more impressive. Thanks to its irreducible quantum zero-point energy, apparently empty space pops and crackles with particles, photons included, that flash out of the vacuum briefly before disappearing again. In 1948, the Dutch physicist Hendrik Casimir predicted that the resulting radiation pressure should create although uncertainties remain about the interpretation.

In Casimir鈥檚 theory, photons should also be created from nothing by moving one of the mirrors at a sizable fraction of light speed, thus squeezing photons out of the vacuum faster than they return into it. Just last month of Chalmers University of Technology in Gothenburg, Sweden, and his team reported evidence of this 鈥�dynamical Casimir effect鈥� ().

If so, that result could link to one of the universe鈥檚 greatest puzzles 鈥� the nature of the dark energy that seems to pop out of the vacuum to permeate the cosmos and ultimately determine its fate. There could hardly be a better exposition of light鈥檚 place in the cosmos: illuminating the universe鈥檚 mysteries on both the smallest and the grandest scales.