| Quantum Tunnelling:
The quantum mechanical effect in which particles have a finite probability of crossing an energybarrier, or transitioning through an energy state normally forbidden to them by classical physics, due to the wave-like aspect of particles. Theprobability wave of a particle represents the probability of finding the particle in a certain location, and there is a finite probability that the particle is located on the other side of the barrier.
Quark:
A type of elementary particle which is the major constituent of matter. Quarks are never found on their own, only in groups of three within composite particles called hadrons (such as protons and neutrons). There are six different types (or “flavours”) of quarks - up, down, top, bottom, charm and strange - and each flavour comes in three “colours” - red, green or blue (although they have no colour in the normal sense, being much smaller than the wavelength of visible light). Quarks are the only particles in the standard model of particle physics to experience all four fundamental forces, and they have the properties of electric charge, colour charge, spin and mass.
Quasar:
Short for QUAsi-StellAr Radio source, a quasar is an extremely powerful and distant active galactic nucleus (a compact region at the centre of a galaxy which has a much higher than normal luminosity). It derives most of its energy from very hot matterswirling into a central supermassive black hole, and can generate as much light as a hundred normal galaxies from a much smaller volume. It is one of the most powerful objects in the universe, and among the most distant things ever seen in space.
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