Nov 14, 2019

Joel Primack, UC Santa Cruz

"11/14/19 Astronomy Colloquium -“Why Galaxies Start Pickle-Shaped”"

According to modern cosmology, invisible dark matter and dark energy drive the evolution of the universe – and astrophysicists are still working out the implications. Newton’s laws explained why planetary orbits are elliptical, but not why the planetary orbits in the solar system are nearly circular, in the same plane, and in the same direction as the sun rotates. Laplace explained this as a consequence of angular momentum conservation as the sun and planets formed in a cooling and contracting protoplanetary gas cloud. For similar reasons, many astronomers once thought that galaxies would start as disks. But Hubble Space Telescope images of forming galaxies instead show that most of them are prolate – that is, pickle-shaped. This turns out to be a consequence of most galaxies forming in prolate dark
matter halos oriented along massive dark matter filaments. This colloquium will includebackground on the 2019 Nobel Prize in Physics to Jim Peebles “for theoretical discoveries inphysical cosmology” [1] and the 2020 Lilienfeld Prize of the American Physical Society to Joel Primack “for seminal contributions to our understanding of the formation of structure in the universe, and for communicating to the public the extraordinary progress in our understanding of cosmology.”[2]

[1] https://www.nobelprize.org/prizes/physics/2019/prize-announcement/,
nobelprize.org/uploads/2019/10/advanced-physicsprize2019.pdf.
[2] https://www.eurekalert.org/pub_releases/2019-08/aps-aa2082719.php,
https://news.ucsc.edu/2019/09/primack-lilienfeld-prize.html. (See also Primack’s popular article
https://www.americanscientist.org/article/why-do-galaxies-start-out-as-cosmic-pickles.)

Event Details

Date:
Nov 14, 2019

Time:
3:30–5pm

Location:
4421 Sterling Hall, 3:30 pm Coffee and Cookies, 3:45 Talk Begins

Speaker Host:
Professor Christy Tremonti and Professor Matt Bershady

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