BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:3
UID:UW-Physics-Event-5226
DTSTART:20191114T213000Z
DTEND:20191114T230000Z
DTSTAMP:20260415T070732Z
LAST-MODIFIED:20191010T181715Z
LOCATION:4421 Sterling Hall\, Coffee and cookies 3:30 PM\, Talk begins
  3:45 PM
SUMMARY:"Why Galaxies are Pickle-Shaped - An historical introduction t
 o Dark Matter and Galaxy formation\, Astronomy Colloquium\, Joel Prima
 ck\, UC Santa Cruz
DESCRIPTION:According to modern cosmology\, invisible dark matter and 
 dark energy drive the evolution of the universe – and astrophysicist
 s are still working out the implications. Newton’s laws explained wh
 y planetary orbits are elliptical\, but not why the planetary orbits i
 n the solar system are nearly circular\, in the same plane\, and in th
 e same direction as the sun rotates. Laplace explained this as a conse
 quence of angular momentum conservation as the sun and planets formed 
 in a cooling and contracting protoplanetary gas cloud. For similar rea
 sons\, many astronomers once thought that galaxies would start as disk
 s. 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 matte
 r halos oriented along massive dark matter filaments. This colloquium 
 will include background on the 2019 Nobel Prize in Physics to Jim Peeb
 les “for theoretical discoveries in physical cosmology” [1] and th
 e 2020 Lilienfeld Prize of the American Physical Society to Joel Prima
 ck “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].<br>

 \n[1] https://www.nobelprize.org/prizes/physics/2019/prize-announcemen
 t/\,<br>
\nnobelprize.org/uploads/2019/10/advanced-physicsprize2019.pd
 f.<br>
\n[2] https://www.eurekalert.org/pub_releases/2019-08/aps-aa208
 2719.php\,<br>
\nhttps://news.ucsc.edu/2019/09/primack-lilienfeld-priz
 e.html. (See also Primack’s popular article<br>
\nhttps://www.americ
 anscientist.org/article/why-do-galaxies-start-out-as-cosmic-pickles.)
URL:https://www.physics.wisc.edu/events/?id=5226
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