Millimeter radio astronomy and the genesis of ALMA

Now nearing completion in northern Chile, the Atacama Large Millimeter/Submillimeter Array (ALMA) is a partnership between North America, Europe, East Asia, and the host country of Chile. ALMA is the first truly global radio astronomy project and arguably, the most complex ground-based astronomical instrument ever built. An imaging interferometer, ALMA provides the point-source sensitivity of a single dish nearly 90 meters in diameter, the ability to observe in all atmospheric windows between 30 and 950 GHz. z and at frequencies above 100 GHz, it provides an angular resolution superior to that of the Hubble Space Telescope. Here I give an overview of the science that drove millimeter and submillimeter radio astronomy from its inception to the start of ALMA construction, and I explain the critical role played by SiS mixer technology in making ALMA possible. In my talk, I shall also present some recent commissioning images from the instrument.