Physics and Astronomy Calendar

Week of Monday, February 19th 2018

Tuesday, February 27th 2018
3:30 pm:
Speaker: Samuel Lederer, MIT
Subject: High temperature superconductivity and strange metal behavior near a metallic quantum critical point

t has long been conjectured that quantum critical points (QCPs) are at the root of some of the most fascinating phenomena in the solid state, including the high temperature superconductivity and “strange metal” behavior of cuprate superconductors. Though much progress has been made in the theory of QCPs, those which occur in metals (and are likely relevant to the high temperature superconductors) are still poorly understood despite more than four decades of effort. Using Quantum Monte Carlo techniques, my collaborators and I have performed the first numerically exact simulations of a model which realizes a metallic QCP towards an Ising nematic ordered phase. I will discuss our results, which include numerous phenomena already observed in experiment, and comment on future avenues towards a solution of this difficult and rich problem in quantum statistical mechanics.

Faculty Host: Rafael Fernandes

Wednesday, February 28th 2018
4:30 pm:
See Joint Quantum Materials & Condensed Matter Seminar on Thursday this week only.

Thursday, March 1st 2018
10:10 am:
Biophysics Seminar in 120 PAN
Speaker: Tanner Akkin, Associate Professor of Biomedical Engineering, University of Minnesota
Subject: Development of a Serial Optical Coherence Scanner for Visualizing and Mapping the Brain with Microscopic Resolution

The feasibility of mapping and imaging the brain with microscopic resolution is presented. A serial optical coherence scanner, which combines a polarization-sensitive optical coherence tomography and a tissue slicer, distinguishes white matter and gray matter and visualizes nerve fiber tracts that are as small as a few tens of micrometers. The technique utilizes the retardance contrast that arise due to the myelination of nerve fibers and the axis orientation contrast that determine the 2D orientation of the nerve fibers, and the technique can be adapted to measure the inclination angle of the fiber, completing the 3D orientation. This scanner could reveal biomarkers for disease onset and progression, and support development of therapeutics.

Speaker: Evan Tyler
3:35 pm:
Speaker: Sara Seager, MIT
Subject: Exoplanets
Joint Colloquium with Earth Sciences (Nier Lecture)
Speaker: Sara Seager, MIT
Subject: Mapping the Nearest Stars for habitable Worlds

Friday, March 2nd 2018
Speaker: Andrew Spray, (IBS, Daejon, Korea)
Subject: TBA
Speaker: Dr. Mateusz Ruszkowski, U. Michigan
Faculty Host: Thomas W. Jones
Speaker: Alisa Bokulich, Department of Philosophy, Boston University
Subject: "Using Models to Correct Data: Paleodiversity and the Fossil Record"
Refreshments served at 3:15 p.m.

It has long been recognized that models play a crucial role in science, and in data more specifically. However, as our philosophical understanding of theoretical models has grown, our view of data models has arguably languished. In this talk I use the case of how paleontologists are constructing data-model representations of the history of paleodiversity from the fossil record to show how our views about data models should be updated. In studying the history and evolution of life, the fossil record is a vital source of data. However, as both Lyell and Darwin recognized early on, it is a highly incomplete and biased representation. A central research program to emerge in paleontology is what D. Sepkoski has called the “generalized” (or what I prefer to call “corrected”) reading of the fossil record. Building on this historical work, I examine in detail the ways in which various models and computer simulations are being used to correct the data in paleontology today. On the basis of this research I argue for the following: First, the notion of a data model should be disentangled from the set-theoretic, ‘instantial’ view of models. Data models, like other models in science, should be understood as representations. Second, representation does not mean perfectly accurate depiction. Data models should instead be assessed as adequate-for-a-purpose. Third, the ‘purity’ of a data model is not a measure of its epistemic reliability. I conclude by drawing some parallels between data models in paleontology and data models in climate science.

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