Textbook models for biological regulation emphasize active mechanisms of signal transduction and chemical signaling, such as protein phosphorylation. However, cells could also achieve control at a more fundamental level by directly sensing changes to the intracellular physical environment. The cell is highly crowded and far from thermodynamic equilibrium. Molecular crowding decreases molecular motion, and also drives interactions through depletion-attraction. We found that crowding is actively regulated in the cell and can tune phase separation. Active processes increase the effective temperature in the cell, helping to fluidize this extreme environment, and depletion of ATP can lead to glass transitions. Therefore, we hypothesize that the interplay between molecular crowding and active processes plays a global role in determining the rates of biochemical reactions. These effects strongly depend on length-scale, such that each biochemical process can potentially respond differently to physical perturbations depending on the size of molecules involved. Thus, the cell can evolve to increase the rates of some reactions and decrease the rates of others in response to changes in crowding or effective temperature. While appealing, the degree to which changes in the physical environment directly regulate biology has been challenging to test in vivo. Indeed mutation of endogenous molecules that impact the material properties or effective temperature of the nucleus necessarily interfere with host biology, leading to pleiotropic effects and making interpretation impossible. To solve this problem, we will: (i) reconstitute transcription within synthetic DNA nanostructure condensates in vitro (Takinoue lead); (ii) develop analogous protein condensates that anchor to specific DNA loci in vivo (Levy lead); and (iii) leverage large-scale genome engineering (Holt lead) to directly address the hypothesis that transcription can dynamically respond to changes in the physical properties of the environment. More generally, responsiveness of biochemistry to physical regulation could represent a primordial and universal level of regulation. Understanding the principles of physical regulation could help elucidate many unresolved conundrums in biology from cell-size control to mechanobiology and this knowledge would significantly improve our ability to engineer cellular systems.