| GLUON | A hypothetical massless subatomic particle believed to bind quarks together (5) |
| GLUONS | Particles believed to bind quarks together |
| NEUTRINO | Nearly massless subatomic particle |
| PRION | Protein particle believed to cause BSE |
| ETHER | Formerly, a hypothetical medium permeating all of space (5) |
| SCHMO | A hypothetical ordinary man, Joe ___ (5) |
| IFSAY | Opening words for a hypothetical example |
| PHOTON | A massless particle which moves at the speed of light in vacuum; it exhibits properties of both waves and particles |
| STRONGINTERACTION | The name for what binds protons and neutrons together and what binds quarks together (6,11) |
| IDEAL | Name given to a hypothetical gas in which atoms do not interact with each other (5) |
| MOOT | Word originally for an assembly or meeting, later a law student's exercise of discussing a hypothetical case; or, by extension, a disputed point (4) |
| SUPEREARTH | Term for a hypothetical exoplanet, larger than our world, yet lighter than gas giants Jupiter, Neptune, Saturn and Uranus (5-5) |
| SCENARIO | A hypothetical sequence of events; a rough outline (8) |
| JOHNDOE | In the US, what name is given to a hypothetical average man? (4,3) |
| MISSINGLINK | The --- ---, a hypothetical animal formerly thought to be intermediate between apes and humans (7,4) |
| EFFECT | Butterfly -; in chaos theory, a hypothetical example (illustrated in fractals) of how small changes can lead to big differences over time (6) |
| LETSPRETEND | Invitation to consider a hypothetical |
| IDEALGAS | A hypothetical substance which obeys Boyle's law exactly at all temperatures and pressures (5,3) |
| IDIC | Of a hypothetical unit of living matter |
| WHATIF | Wicket taken by bowler, say, with one following? A hypothetical scenario |
