[Definr]a collection of star systems, any of the billions of systems each having many stars and nebulae and dust
[Definr]The ratio of the volume of void space to the volume of solid substance in any material consisting of void space and solid material, such as a soil sample, a sediment, or a powder.
[Definr]he branch of galaxy and stars that deals with the physics of stellar phenomena.
[Definr]A mysterious force that appears to be causing the expansion of the universe to accelerate
[Definr]a process in which something passes by degrees to a different stage (especially a more advanced or mature stage)
used in negative statement to describe a situation that has existed up to this point or up to the present time
[Dictionary.com]a theory that predicts the existence of heavy to all known particles. it will be tested in the LHC
[Dictionary.com]a space entirely devoid of matter; a state of lowest energy in a quantum field theory
[Dictionary.com]Physics The tendency of particles or bodies of the same electric charge or magnetic polarity to separate.
[Dictionary.com]generalization that the speed of recession of distant galaxies (the red shift) is proportional to their distance from the observer