I am interested in studying the physical properties and evolution of galaxies using telescope data from ultraviolet to radio wavelengths. Ten billion years ago, the star formation rate density of the Universe peaked and individual galaxies were forming more stars that at any other time in cosmic history. Whether star formation at this cosmic noon resembles star formation today or was more efficient remains a key question for galaxy evolution. The answer lies in the details of energy transfer in galaxies. Dissipative processes allow interstellar dust and gas to cool and form stars, which then re-inject heat through radiation and mechanical processes. The intimate link between star formation and the interstellar medium (ISM) manifests in global scaling relations like the Kennicut-Schmidt law. Thus, the star formation rate density peak ten billion years ago is naturally linked to the physical evolution of the ISM; however, the detailed nature of galaxies forming tens to hundreds of new stars each year remains uncertain. What physical mechanisms drove the greatest period of galactic structure evolution in the history of the Universe? I aim to answer this question by studying key atomic and molecular emission lines using ground- and space-based telescopes such as Spitzer, Hubble Space Telescope, Herschel, ALMA, VLA and LMT.