Cosmic acceleration is one of the most surprising cosmological discoveries of the past century. Even the "simplest" explanations require new, cosmologically dominant energy components with exotic physical properties. Current and near-future experiments are seeking clues to the origin of cosmic acceleration by measuring the history of expansion and structure growth with sub-percent precision over a wide span of redshift. I will review the observational methods that underpin these measurements and assess the current state of play. A model based on cold dark matter and a cosmological constant explains a wide range of observations at the 5-10 percent level, but at higher precision there are several intriguing tensions, including a mismatch between the predicted and measured amplitude of matter clustering and a mismatch between the value of the Hubble constant inferred from high-redshift data and measured via the Cepheid+SNIa distance ladder. I will discuss the prospects and challenges for the new generation of experiments — DESI, Euclid, Rubin, Roman — which aim to sharpen cosmological measurements by a factor of ten.

Speaker: David Weinberg (Ohio State University)

The 2024 Fall Colloquium talks are held on Wednesdays at 3:00 PM. This colloquium is hosted by STScI and will be held as an in-person and virtual event.

You may join in person at STScI’s John N. Bahcall Auditorium or virtually on STScI's Live Science Events Facebook page.

Please direct questions or comments to contact above. The 2024 Fall Colloquium Committee members are: Nestor Espinoza (STScI), Joel Green (STScI), Nick Indriolo (STScI), Elena Manjavacas (STScI), Namrata Roy (JHU), Kevin Schlaufman (JHU), Ethan Vishniac (JHU).