Pushing high-energy neutrino physics to the cosmic frontier

<!--HTML--><p>High-energy (TeV-PeV) and ultra-high-energy (&gt; 100 PeV) neutrinos of cosmic origin have a vast potential to probe neutrino physics in regimes of energy and distance otherwise unreachable. Notable examples include precision tests using the flavor composition of the neutrino flux, new neutrino-neutrino interactions, and measuring the neutrino-nucleon cross section. Today, we are already tapping into this potential at high energies, thanks to spectacular discoveries by the IceCube neutrino telescope.&nbsp; In the coming decade, we may extend our reach to ultra-high energies, thanks to an ambitious experimental program under planning.&nbsp; I will survey the rich landscape of high-energy physics with cosmic neutrinos, from the perspectives of theory and experiment.&nbsp; By means of illustration, I will campaign for the notion that in order for the field to mature, we must embrace the natural synergy between low-energy and high-energy neutrino experiments, and adopt an earnest, comprehensive treatment of the relevant particle-physics and astrophysical unknowns.&nbsp; If we do, then our progress, while hard-earned, could lead to transformative insight.</p> TH colloquia: https://cern.zoom.us/j/67346292748?pwd=ZnRkQWh0ZXVFQTc5K256QW5NcEcrdz09