Higgs boson moving through the Higgs field, causing ripples as it moves. The Higgs field explains why some particles have mass and some do not _ if a particle interacts with the Higgs field, as this boson does, it has mass. This is described by analogy to a particle moving through a viscous fluid the Higgs field, and being slowed by it. Particles that do not interact with the fluid such as photons are not slowed by it, and thus are massless and move at the speed of light. See clip K003/1517 for massless particles not interacting with the Higgs field. Although the Higgs mechanism is accepted due to substantial evidence, the existence of the Higgs boson itself the quantum of the Higgs field has not yet been confirmed or ruled out.