How the Milky Way ticks: comprehending complexity in the interstellar medium, from ethereal wisps to dense structures at the onset of star formation

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I want to understand how our Milky Way Galaxy ticks, why, unlike in other galaxies, there is still an interstellar medium (ISM) in which stars are continually forming. This requires a broad program to understand Galactic ecology, the cycling of the ISM from the diffuse atomic phase to dense molecular clouds, the sites of star formation, and back. So complex is the ISM that comprehending the structure and dynamics at the key stages, from ethereal wisps to dense structures at the onset of star formation, requires exploitation and synthesis of all available multiwavelength data. I am working with international teams at a new frontier revolutionizing this field, in the submillimetre with the Herschel and Planck satellites which image thermal emission by small interstellar dust particles tracing the gas. Deciphering the fascinating evolution of dust becomes necessary because dust is implicated in so many key interstellar processes. An exciting new insight from Planck is polarization, probing the important role of the interstellar magnetic field in the life cycle. A key question that will be addressed is the state of the ISM in the hitherto elusive earliest stages of star formation, before substantial accretion and nuclear ignition reveal new stars. The compact structures that we can now detect in the submillimetre are cold condensations, starless cores. How these form and the dependence on environment are still unkown, but progess can be made by relating the onset and efficiency of core formation, and their mass function, to the larger-scale high column density structures like filaments, and tracing the thermal and dynamical state with molecular line probes. At high Galactic latitudes we see the return cycle, the interstellar cirrus, fairly local gas and dust in the disk, as well as intermediate velocity clouds, part of the Galactic fountain, material thrust out of the disk and circulating in the halo. Comprehending the turbulent structure of the cirrus is essential to learning how molecular clouds form, and has another huge impact because cirrus is a polarized foreground that must be removed to reach the cosmological goals of studies of the cosmic microwave and infrared backgrounds.