Please note extended discussion at the end of the colloquium.
The Stage-IV Dark Energy experiments DESI and LSST will provide exquisite measurements of the distance-redshift relation and growth of structure out to z<1.5, but a large number of non-linear modes will still be available for spectroscopic observation. At z>2, DESI measurements of clustering in the Lyman-alpha forest will provide BAO measurements at ~1% precision while cross-correlations between CMB, LSST, and spectroscopic quasars offer additional cosmological probes. However, this redshift range will be far from cosmic-variance limited, leaving potential for future z>2 measurements of non-Gaussianity, the BAO distance scale, and growth of structure. SpecTel is a telescope design that provides an order of magnitude increase in collecting area with a focal plane that can host an order of magnitude increase in multiplex, thus allowing a large Stage-V spectroscopic program to advance the cosmological model over the full redshift range 0<z<4. In this talk, I will present the telescope design, R&D needs, and a high-level overview of the potential science cases that can be pursued with such a facility.