Five decades ago, astronomers finally broke free of the boundaries of light when a new science, radio astronomy, was born. This new way of 'seeing' rapidly uncovered a range of unexpected objects in the cosmos. This was our first view of the non-thermal universe, and our first un obscured view of the universe. In its short life, radio astronomy has had an unequaled record of discovery, including four Nobel prizes: Big-Bang radiation, neutron stars, aperture synthesis and gravitational radiation. New technologies now make it possible to construct new and upgraded radio wavelength arrays which will provide a powerful new generation of facilities. Radio telescopes such as SKA and the upgraded VLA will have orders of magnitude greater sensitivity than existing facilities. They will be able to study thermal and non-thermal emission from a wide range of astrophysical phenomena throughout the universe as well as greatly extending the range of unique science accessible at radio wavelengths.
