New Physics in the Cosmological Desert

As cosmological datasets have grown and matured, we have reached a point where cosmology beyond LCDM can be studied. As we proceed, we find ourselves in an era where the physics dominating the universe in the eV to MeV temperature range will be tested. Anomalies such as the Hubble tension have driven interest in considering a host of new ideas, including novel forms of energy and radiation which can alter the cosmology we observe. I will discuss scenarios and motivations - theoretical and experimental - for what physics can arise that may show itself in the coming years.