Is there a dark energy particle?

A theoretical particle that adapts to its surroundings could explain the accelerating expansion of our universe. Our universe grows a little bigger every day. Empty space is expanding, sweeping galaxies further and further apart. Even starlight traversing this swelling nothingness is stretched like a rubber band. The astronomical evidence for the accelerating expansion of the universe is overwhelming. But what is pushing the universe apart? Particle physicists endeavor to answer cosmic-sized que...