"The world's largest particle collider passed its first major tests by firing two beams of protons in opposite directions around a 17-mile underground ring ... After a series of trial runs, two white dots flashed on a computer screen at 10:26 a.m. indicating that the protons had traveled clockwise along the full length of the 4 billion Swiss franc (US$3.8 billion) Large Hadron Collider."
— from Massive particle collider passes first key tests
What better way to indicate a passing test than a single dot?! Simple, effective. Mmmm, dots.