A complete theory of galaxy formation requires understanding the details of how gas is converted into stars over cosmic time, which is affected by gas supply, star formation, and feedback-driven outflows. I will present a physical picture for galaxy formation that exhibits two distinct phases: at high redshift, stellar feedback causes all star-forming galaxies to undergo rapid fluctuations in their star formation rates on ~10-Myr timescales. Bursts of star formation are followed by strong outflows, which cause the star formation rate to drop precipitously. Fresh gas supply from galactic fountains rejuvenates star formation and restarts the cycle. At z ~ 1, simulations of massive galaxies exhibit a qualitative transition: outflows are no longer driven effectively, and the galaxies transition to steadily star-forming, well-order disk galaxies. I will discuss the physical causes of bursty star formation and the aforementioned transition to time-steady star formation, in addition to some implications for JWST observations of high-redshift galaxies. I will also describe how we can test this theoretical picture via more sophisticated comparisons between theoretical models and observations than are currently performed.
