Think of the proton as a black night with the gluons like fireflies blinking on and off,” Venugopalan said. “A snapshot with the proton at rest will reveal an ephemeral and diffuse glow from the fireflies whose flicker is barely visible in the darkness. With finer resolution snapshots, one may be able to determine the density of fireflies, localize them better spatially, and even extract details about their motion as they whirl about.

Very interesting results coming out of work on quark-gluon plasma from colliding heavy ions (in this case, gold nuclei) at almost light speed. Photons, which carry the electromagnetic force, do not interact with each other, and a dense concentration of photons behaves somewhat like an ideal gas. Gluons, which carry the strong force, do interact with each other, and the dense concentration of gluons behaves somewhat like an ideal liquid, and not a gas as was expected. The gluon-gluon interactions makes a significant different, and makes strong force calculations much harder than one finds with the electromagnetic force.

As usual, more questions are raised which require a bigger, more powerful machine to whip particles ever closer to the speed of light, reducing their wavelength and enabling finer and finer resolution of what happens at the amazingly small scale of quarks in hadrons.

The quote above paints a beautiful picture, to me, of how virtual gluons–really, the smallest disturbances in the strong force field–wink into existence briefly due to the Heisenburg uncertainty in system energy. Nature is both subtle and beautiful in ways that challenge human understanding.