aether amplitude antimatter antiparticle astrophysics atom atomic attract attraction ballistics beam black hole buoyancy calorie calorific capillary action cathode ray tube centre of gravity centrifugal force centrifuge centripetal force chain reaction condensation conduct conduction conductive conductor convect convection core critical mass demagnetize dense density displacement dynamic electron elementary particle fallout fissile fission focus frequency friction fusion gamma ray gravitation gravitational gravity half-life hertz hydraulic Hz imaging impetus inertia invariable ion ionize kinetic laser lift liquefaction liquefy lodestone magnet magnetic magnetic field magnetism magnetize mass mechanical medium meltdown momentum motive mushroom cloud natural philosophy neutron Newtonian nuclear nuclear fission nuclear fusion nuclear physics nuclear reactor nucleus optical fibre particle accelerator particle physics phonic phosphorescence phosphorescent photo- photon photosensitive photosensitize physical physicist physics pivot polar pole power pressure propulsion proton pull quantum mechanics quantum theory quark radiate radiation radio wave ray reaction reactor reflect reflector refract relativity repel repulsion repulsive resilience resilient resistance resonance retention solid-state sonic sonic boom sound wave space specific gravity spectral spectroscope spectrum statics steady state theory strain stress surface tension tension thermodynamics thrust traction trajectory transmit ultrasonic ultrasound vacuum vaporize vapour vector wave wavelength work