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Events on Tuesday, February 18th, 2020

Chaos & Complex Systems Seminar
Drivers of megadiversity in the orchids, the largest family of flowering plants
Time: 12:05 pm - 1:00 pm
Place: 4274 Chamberlin (refreshments will be served)
Speaker: Tom Givnish, UW Department of Botany
Abstract: Orchids are the most diverse family of angiosperms, with more species than mammals, birds, and reptiles combined. Many ideas have been advanced to account for their extraordinary diversity, but they have – until quite recently – been impossible to test because we lacked a good phylogeny (family tree) for the orchids. My colleagues and I have now developed a well-resolved phylogeny for the orchids, based on large numbers of chloroplast genes, and I will show how we can use this phylogeny to identify the age and place of origin of the orchids, assess the role of different orchid traits in driving high rates of speciation, and reconstruct the geographic spread of orchids across the planet. I will also describe some of the remarkable aspects of the ecology of this endlessly fascinating group that have recently come to light, mention some of the notable aspects of orchid diversity in Wisconsin, and sketch some interesting scientific and conservation issues that should be explored in the future.
Host: Clint Sprott
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"Physics Today" Undergrad Colloquium (Physics 301)
Dark Matter Detection in the Era of LZ
Time: 1:20 pm - 2:10 pm
Place: 2241 Chamberlin Hall
Speaker: Kimberly J. Palladino, UW Madison Department of Physics
Host: Sridhara Dasu
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Theory Seminar (High Energy/Cosmology)
Connecting the dots: from astronomical surveys and experiments to fundamental physics of dark universe
Time: 4:00 pm
Place: 5280 Chamberlin
Speaker: Yao-Yuan Mao, Rutgers
Abstract: The standard model of cosmology, despite its success in explaining most current observations, consists of several mysterious components, such as dark matter, dark energy, and inflation. Current and upcoming multiwavelength sky mappers, gravitational wave observations, and particle experiments will provide an unprecedented collection of complementary datasets, which have brought, and will continue to bring us novel and exciting discoveries. One of the main challenges in the next decade is to translate these discoveries into solid understandings of the fundamental physics of the universe, especially its dark components. We hence need to carefully connect the “dots” between theories and observations. In this talk, I will demonstrate the pivotal roles of numerical simulations, empirical models, and statistical analyses in the said connection. I will illustrate how theoretical uncertainties impact the interpretation of observations and how we mitigate those impacts, with specific case studies including direct detection experiments, gravitational lensing, and dwarf galaxy surveys (as dark matter probes). Finally, taking the LSST Dark Energy Science Collaboration as an example, I will discuss how we work together as a community to be prepared to answer fundamental questions about the dark universe with upcoming datasets.
Host: Dan Chung
Presentation: Mao_Connecting-the-dots_Feb2020.pdf
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