Past Speakers

Monday, May 9, 2016

Inside-Out Planet Formation

Jonathan C. Tan University of Florida

AST Colloquium

Inside-Out Planet Formation

Jonathan C. Tan University of Florida
Monday, May 9, 2016

The Kepler-discovered systems with tightly-packed inner planets (STIPs), typically with several planets of Earth to super-Earth masses on well-aligned, sub-AU orbits may host the most common type of planets in the Galaxy. They pose a great challenge for planet formation theories, which fall into two broad classes: (1) formation further out followed by migration; (2) formation in situ from a disk of gas and planetesimals. I review the pros and cons of these classes, before focusing on a new theory of sequential in situ formation from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (~cm-m size) "pebbles," drifting inward via gas drag. Pebbles first collect at the pressure trap associated with the transition from a magnetorotational instability (MRI)-inactive ("dead zone") region to an inner MRI-active zone. A pebble ring builds up until it either becomes gravitationally unstable to form an Earth to super-Earth-mass planet directly or induces gradual planet formation via core accretion. The planet continues to accrete until it becomes massive enough to isolate itself from the accretion flow via gap opening. The process repeats with a new pebble ring gathering at the new pressure maximum associated with the retreating dead-zone boundary. I discuss the theory’s predictions for planetary masses, relative mass scalings with orbital radius, and minimum orbital separations, and their comparison with observed systems. Finally I speculate about potential causes of diversity of planetary system architectures, i.e. STIPs versus Solar System analogs.

Monday, May 2, 2016

Unveiling the dark side of the Universe

Priya Natarajan Yale University

AST Colloquium

Unveiling the dark side of the Universe

Priya Natarajan Yale University
Monday, May 2, 2016

Dark matter and Dark Energy, the enigmatic dominant constituents of our Universe shape the properties of structures. However, their essential nature remains unknown.
Gravitational lensing, the bending of light by matter predicted by Einstein's Theory of General Relativity offers a powerful probe of both dark matter and dark energy. Deploying
clusters of galaxies as gravitational lenses a viewed by the Hubble Space Telescope we have many interesting new results - I will present a status report of recent progress in 
this talk.

Monday, April 25, 2016

Dusty Universe

Asantha Cooray University of California, Irvine

AST Colloquium

Dusty Universe

Asantha Cooray University of California, Irvine
Monday, April 25, 2016

Dr. Cooray will summarize the scientific case for studying the universe and Far-Infrared and sub-millimeter wavelengths. She will present results from Herschel,  summarize on going plans for ground-based instruments, and outline the ongoing Far-Infared Surveyor study facilitated by NASA for 2020 Decadal Surveyor.


Monday, March 21, 2016

Galaxy Mergers on FIRE: Mapping Star Formation

Jorge Moreno Cal Poly Pomona

AST Colloquium

Galaxy Mergers on FIRE: Mapping Star Formation

Jorge Moreno Cal Poly Pomona
Monday, March 21, 2016

Galaxy mergers and interactions are responsible for generating bursts of star formation, for changing galactic morphology in dramatic ways, and for triggering single and dual active galactic nuclei. In this talk, I will unveil the very first results from a novel suite of high-resolution galaxy merger simulations, based on the “Feedback In Realistic Environments” (FIRE) model. This model treats energy and momentum-driven feedback from young stars and SN explosions explicitly, which acts directly on resolved star-forming clouds within the ISM. Moreover, this framework relies on a new meshless Lagrangian hydro code, GIZMO, which solves many problems associated with older solvers. Our first work focuses on the spatial localization of star formation. In particular, we confirm results from previous work: galaxy-galaxy interactions enhance nuclear star formation, and suppress it at large galacto-centric radii (Moreno et al. 2015). However, two major differences are found. First, star-formation enhancement and suppression are not as dramatic as in older models. Secondly, the interaction-induced nuclear starburst has a larger spatial extent. These differences are a reflection of the fact that, in our new models, non-axisymmetric gravitational torques are not as effective at driving fuel into the central regions as in older sub-grid based models. This suite of merger simulations is ideal for making predictions for, and interpreting results from, observations by new-generation integral field spectroscopic surveys, such as CALIFA, MaNGA and HECTOR.


Monday, March 7, 2016

New astronomical projects from Japan: TAO and the Tomo-e Gozen Camera

Mamoru Doi University of Tokyo

AST Colloquium

New astronomical projects from Japan: TAO and the Tomo-e Gozen Camera

Mamoru Doi University of Tokyo
Monday, March 7, 2016

The Institute of Astronomy, part of the University of Tokyo's School of Science, is currently operating two observatories: the Tokyo Atacama Observatory (TAO) in Chile, and the Kiso Observatory in Nagano, Japan.  The goal of TAO is to operate a 6.5-m optical-infrared telescope at Cerro Chajnantor in Chile (elevation 5,640m), the world's highest site for an astronomical observatory. A pathfinder telescope, the miniTAO 1.0-m telescope, has been operating there since 2009, and we can confirm that it opens new atmospheric windows in the mid-infrared. I will review the current status of the TAO project as well as early results from miniTAO.
At the Kiso observatory, we are developing a new wide-field imager, the Tomo-e Gozen Camera, which is going to use 84 CMOS sensors. I will show some early results from a prototype camera with 8 CMOS sensors, called Tomo-e PM.

Monday, February 29, 2016

The Biggest Blowhards: Windy Supermassive Black Holes

Sarah Gallagher Western University

AST Colloquium

The Biggest Blowhards: Windy Supermassive Black Holes

Sarah Gallagher Western University
Monday, February 29, 2016

Supermassive black holes reside in the centers of every massive galaxy. In relatively brief spurts, black holes grow as luminous quasars through the infall of material through an accretion disk. Remarkably, the light from the accretion disk can outshine all of the stars in the host galaxy by a factor of a thousand, and this radiation can also drive energetic mass outflows. Mass ejection in the form of winds or jets appears to be as fundamental to quasar activity as accretion, and can be directly observed in many objects with broadened and blue-shifted UV emission and absorption features. A convincing argument for radiation pressure driving this ionized outflow can be made within the dust sublimation radius. Beyond, radiation pressure is still important, but high energy photons from the central engine can now push on dust grains. This physics underlies the dusty wind picture for the putative obscuring torus. I'll describe our model of the dusty wind and evaluate its successes and shortcomings in accounting for observed properties of quasars such their mid-infrared power, fractions of hidden objects, and column densities of important ions.

Monday, December 7, 2015

Cosmological Simulations of Galaxy Formation and Evolution

Lars Hernquist Harvard-Smithsonian Center for Astrophysics

AST Colloquium

Cosmological Simulations of Galaxy Formation and Evolution

Lars Hernquist Harvard-Smithsonian Center for Astrophysics
Monday, December 7, 2015

A predictive theory of galaxy formation remains elusive, even after more than 50 years of dedicated effort by many renowned astrophysicists.  The problem of galaxy formation is made difficult by the large range in scales involved and the many non-linear physical processes at work.  In this talk, I describe a new generation of numerical models designed to overcome these difficulties based on novel schemes for solving the fluid equations on a moving mesh. Initial results from this study provide insight into many aspects of galaxy assembly and the relationship between galaxies and cosmologically-distributed baryons.


Monday, November 23, 2015

Dark Energy Spectroscopic Instrument

Peter Nugent University of California, Berkeley

AST Colloquium

Dark Energy Spectroscopic Instrument

Peter Nugent University of California, Berkeley
Monday, November 23, 2015

The Dark Energy Spectroscopic Instrument (DESI) will measure the effect of dark energy on the expansion of the universe.  It will obtain optical spectra for tens of millions of galaxies and quasars, constructing a 3-dimensional map spanning the nearby universe to 10 billion light years over 14,000 square degrees of sky.  DESI’s key project goals are to (a) probe the effects of dark energy on the expansion history using Baryon Acoustic Oscillations and (b) measure the gravitational growth history using redshift-space distortions. DESI will be conducted on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018. Here I will describe the overall design of the experiment, its current status and the massive photometric targeting surveys being carried out now in preparation for DESI. 

Monday, October 19, 2015

Successes and failures of LambdaCDM and its alternatives

Benoit Famaey Universite de Strasbourg

AST Colloquium

Successes and failures of LambdaCDM and its alternatives

Benoit Famaey Universite de Strasbourg
Monday, October 19, 2015

While there is indisputable observational evidence for a new degree of freedom behaving as a collisionless fluid of particles on large scales, i.e. dark matter, there is no such solid evidence on galaxy scales. On the contrary, the current LambdaCDM model of cosmology is plagued with numerous challenges at these scales, which we review here. These small-scale-problems of cosmology include the mismatch between the predicted and much smaller observed number of satellite galaxies in the Local Group (missing satellite problem), the shape of the inner dark matter distribution in galaxies (core-cusp problem), the concentration of sub-halo potential in satellite galaxies (too-big-to-fail problem), or the phase-space distribution of satellite galaxies (satellite plane problem). These challenges might not directly indicate a failure of the standard model of cosmology since, until recently, baryonic physics has largely been ignored in the simulations, but might be able to alleviate many of the problems. However, we argue that the observational evidence for an intimate connection between the baryonic surface density and the total gravitational field in spiral galaxies presents a severe fine-tuning problem for any particle dark matter interpretation of galactic mass discrepancies. On the other hand, it is obvious that any alternative to the standard model of cosmology must also, in fine, reproduce the successes of this model on large scales, where it is so well-tested that it presents by itself a challenge to any such alternative.

Monday, October 12, 2015

Exoplanet Climatology: The Next Era of Habitable-planet Hunting

Aomawa Shields UCLA/Harvard

AST Colloquium

Exoplanet Climatology: The Next Era of Habitable-planet Hunting

Aomawa Shields UCLA/Harvard
Monday, October 12, 2015

 The identification of an exoplanet receiving the amount of incident radiation from its host star to lie within the star¹s habitable zone has been the primary step taken in classifying a planet as "potentially habitable". However, recent research and the history of our own planet has shown that many factors and processes other than orbital distance can affect climate and planetary habitability. Discovering a planet in the habitable or "Goldilocks" zone is therefore but a first step in the process of finding the next planet where life can survive. To identify habitable exoplanets, it is important to understand how both orbital and atmospheric properties affect the climate of exoplanets, and how these climatic effects might change for different stellar and planetary environments. I will share results from work performed using a hierarchy of models to simulate planets orbiting stars of different spectral types and with varied orbital architectures, and discuss the implications of these results for planetary climate and habitability. My methods can be used to assess the possible climates of potentially habitable planets as they are discovered. This work ushers in a new era of utilizing observational and theoretical techniques together to target the next planet where life exists.

Monday, October 5, 2015

Star Formation in the Midst of Upheaval - Goings On in the Centers of Rich Clusters of Galaxies

Stefi Baum University of Manitoba

AST Colloquium

Star Formation in the Midst of Upheaval - Goings On in the Centers of Rich Clusters of Galaxies

Stefi Baum University of Manitoba
Monday, October 5, 2015

How and where does star formation occur in elliptical galaxies sitting at the centers of rich clusters of galaxies in the midst of cooling cores of hot-xray gas, mergers of galaxies, and powerful outflowing jets emanating from a central black hole? Recent ALMA (millimeter),  HST (ultraviolet) and Ground Based (Optical) observations reveal more detailed information on the interplay of energetics, activity and star formation in these unique environments.


Sunday, September 27, 2015

RIT Observatory: Open House


AST Colloquium

RIT Observatory: Open House

Sunday, September 27, 2015


Monday, September 21, 2015

Rings and Radial Waves in the Milky Way's Stellar Disk

Heidi Newberg Rensselaer Polytechnic Institute

AST Colloquium

Rings and Radial Waves in the Milky Way's Stellar Disk

Heidi Newberg Rensselaer Polytechnic Institute
Monday, September 21, 2015

Abstract: I will show that there is an asymmetry in the main sequence star counts on either side of the Galactic plane, as one looks towards the Galactic anticenter. This can be explained if the disk of the Milky Way oscillates up and down. This oscillation could provide an explanation for the Monoceros Ring, and also for the TriAndromeda Stream (or Ring). The implication is that the stellar disk extends out to at least 25 kpc from the Galactic center - much farther than the canonical 15 kpc that is typically quoted. The oscillations are aligned with the spiral arms of the Milky Way, and are plausibly consistent with previous predictions for disk ringing due to a Sagittarius dwarf-sized galaxy plunging through the disk.


Monday, May 11, 2015

What neutrinos and magnetic turbulence do to nuclear-density toroidal stars and disks: some numerical relativity models

Matthew Duez Washington State University

AST Colloquium

What neutrinos and magnetic turbulence do to nuclear-density toroidal stars and disks: some numerical relativity models

Matthew Duez Washington State University
Monday, May 11, 2015


Monday, May 4, 2015

RR Lyrae Stars in M31, M32 and M33

Ata Sarajedini University of Florida

AST Colloquium

RR Lyrae Stars in M31, M32 and M33

Ata Sarajedini University of Florida
Monday, May 4, 2015


Monday, April 27, 2015

Gas in Local Dwarf Galaxies

Jana Grcevich American Museum of Natural History

AST Colloquium

Gas in Local Dwarf Galaxies

Jana Grcevich American Museum of Natural History
Monday, April 27, 2015


Monday, April 20, 2015

Scrutinizing the Relationship Between Galaxies and Supermassive Black Holes

Jillian Bellovary Vanderbilt University

AST Colloquium

Scrutinizing the Relationship Between Galaxies and Supermassive Black Holes

Jillian Bellovary Vanderbilt University
Monday, April 20, 2015


Monday, April 13, 2015

[Re]Exploring the Universe with [NEO]WISE

Edward (Ned) Wright UCLA

AST Colloquium

[Re]Exploring the Universe with [NEO]WISE

Edward (Ned) Wright UCLA
Monday, April 13, 2015


Friday, March 20, 2015

Observable Signatures of Neutron Star Mergers

Brian Metzger Columbia University

AST Colloquium

Observable Signatures of Neutron Star Mergers

Brian Metzger Columbia University
Friday, March 20, 2015


Monday, March 16, 2015

Bose-Einstein Condensate Axion Dark Matter

Chanda Prescod-Weinstein MIT

AST Colloquium

Bose-Einstein Condensate Axion Dark Matter

Chanda Prescod-Weinstein MIT
Monday, March 16, 2015


Monday, December 1, 2014

"Tension" in the Extragalactic Distance Scale and "New Physics": Ending the Debate over the Hubble Constant

Barry Madore Carnegie Observatories

AST Colloquium

"Tension" in the Extragalactic Distance Scale and "New Physics": Ending the Debate over the Hubble Constant

Barry Madore Carnegie Observatories
Monday, December 1, 2014


Monday, November 24, 2014

Determining the Cause of Cosmological Acceleration with Large Astronomical Surveys

Andrew Zentner University of Pittsburgh

AST Colloquium

Determining the Cause of Cosmological Acceleration with Large Astronomical Surveys

Andrew Zentner University of Pittsburgh
Monday, November 24, 2014


Friday, November 21, 2014

Are exoplanets really tidally synchronized?

Jeremy Leconte University of Toronto (CITA)

AST Colloquium

Are exoplanets really tidally synchronized?

Jeremy Leconte University of Toronto (CITA)
Friday, November 21, 2014


Monday, October 27, 2014

Where's the Matter? : Tails form the Milky Way's Past

Kathryn Johnston Columbia University

AST Colloquium

Where's the Matter? : Tails form the Milky Way's Past

Kathryn Johnston Columbia University
Monday, October 27, 2014


Monday, October 6, 2014

The Physics of Evolved Stars

Jason Nordhaus RIT NTID

AST Colloquium

The Physics of Evolved Stars

Jason Nordhaus RIT NTID
Monday, October 6, 2014


Monday, September 22, 2014

Roving the Red Hills of Mars

Shoshanna Cole Cornell University

AST Colloquium

Roving the Red Hills of Mars

Shoshanna Cole Cornell University
Monday, September 22, 2014


Thursday, April 21, 2016

Field E ect Electro-Absorption Modulator Based on Conductive Oxide

Kaifeng Shi Novel Material Photonics Group Rochester Institute of Technology

Photons After Dark

Field E ect Electro-Absorption Modulator Based on Conductive Oxide

Kaifeng Shi Novel Material Photonics Group Rochester Institute of Technology
Thursday, April 21, 2016

The lack of ultracompact, high speed, broadband electro-optical (EO) modulators impedes the wide applications of integrated photonic circuits. Novel approaches and materials need to be explored to overcome the technical barrier. In this talk, I will present an EO mod-ulator, more specically electro-absorption (EA) modulator, based on a novel yet inexpensive active material, conductive oxide (COx), which exhibits moderate carrier concentration for tele-com application. Light modulation is realized through the eld eect in a metal-insulator-COx(MIC) structure. Dielectric constant epsilon-near-zero (ENZ) state is observed. Furthermore, we investigate an MICIM plasmonic EA modulator with a waveguide length of only 800 nm. The modulator can potentially operate at high speed.


Tuesday, March 15, 2016

Quantum Integrated Photonics: A source of spectrally indistinguishable photons

Michael L. Fanto Nanophotonics Group @ RIT

Photons After Dark

Quantum Integrated Photonics: A source of spectrally indistinguishable photons

Michael L. Fanto Nanophotonics Group @ RIT
Tuesday, March 15, 2016

Quantum information science relies on the property of quantum interference, where the interference quality correlates to the indistinguishability of the interacting particles. The creation of these indistinguishable particles, photons in this case, has conventionally been accomplished with nonlinear crystals and optical filters to remove spectral distinguishability, albeit sacrificing the number of photons. This research describes the use of an integrated silicon microring resonator circuit to selectively generate photon pairs at the narrow cavity transmissions, thereby producing spectrally indistinguishable photons, and then entangle the resulting photon pair.


Wednesday, February 17, 2016

Designing a spatial mode sorting interferometer

Tanya Malhotra University of Rochester

Photons After Dark

Designing a spatial mode sorting interferometer

Tanya Malhotra University of Rochester
Wednesday, February 17, 2016

The ability to decompose an optical beam/scene into a specific modal basis is desirable in a wide array of optical technologies. By generalizing the delay line in a conventional Michelson interferometer to an arbitrary unitary transformation, it becomes possible to unlock the full mode sorting ability of the interferometer. Specifically, the eigenfunctions of the generalized delay line are the basis in which beam modal analysis is possible. In the following we describe an approach to arbitrary spatial mode sorting based on two-path interferometry. Our proof-of-principle mode sorting demonstration is based on the fractional Fourier transform (fFT). When replacing the conventional temporal delay line in the interferometer with an optical implementation of the fFT, the interferometer is able to decompose an input optical beam in terms of its constituent HG modes which are the fFT eigenmodes.


Wednesday, November 18, 2015

State transfer based on classical nonseparability

Seyed Mohammad Hashemi Rafsanjani Institute of Optics @ the University of Rochester

Photons After Dark

State transfer based on classical nonseparability

Seyed Mohammad Hashemi Rafsanjani Institute of Optics @ the University of Rochester
Wednesday, November 18, 2015

We discuss recent interest in appearance of entanglement in classical physics. We demonstrate a protocol that utilizes nonseparability between different degrees of freedom of a beam of light to transfer an arbitrary and a priori unknown, state of two different OAM modes onto the polarization, in a fashion that is analogous to teleportation using quantum entanglement.


Tuesday, October 13, 2015

Exotic Effects in Optical Coherence

Omar S. Magaña-Loaiza Institute of Optics @ the University of Rochester

Photons After Dark

Exotic Effects in Optical Coherence

Omar S. Magaña-Loaiza Institute of Optics @ the University of Rochester
Tuesday, October 13, 2015

In this talk I will describe our recent contributions to the field of exotic effects in optical coherence. I will start by describing how the chaotic fluctuations of light can give rise to the formation of correlations in the orbital angular momentum (OAM) components and angular positions of pseudothermal light. The presence of these correlations is manifested through a new family of exotic interference structures in the OAM distribution of random light.  In addition, it has been recently predicted that the finite probability of a photon to follow looped paths in a three-slit interferometer produces an apparent deviation from the most conventional form of the superposition principle. However, the probability of observing these exotic paths is very small and thus extremely hard to be measured. I will discuss how we have increased the probability of photons to follow such looped trajectories and measured its contributions to the formation of interference fringes. 


Wednesday, September 16, 2015

Photons After Dark: Robin Sharma

Robin Sharma Institute of Optics @ the University of Rochester

Photons After Dark

Photons After Dark: Robin Sharma

Robin Sharma Institute of Optics @ the University of Rochester
Wednesday, September 16, 2015

 

 


Wednesday, April 15, 2015

Twisting starlight to directly image exoplanets

Garreth Ruane RIT, Center for Imaging Science

Photons After Dark

Twisting starlight to directly image exoplanets

Garreth Ruane RIT, Center for Imaging Science
Wednesday, April 15, 2015


Wednesday, March 18, 2015

A physicist in the woods: closing the fire energy budget


Photons After Dark

A physicist in the woods: closing the fire energy budget

Wednesday, March 18, 2015


Wednesday, November 19, 2014

Measuring Photons with a "Light" touch

Mohammad Mirhosseini Institute of Optics @ the University of Rochester

Photons After Dark

Measuring Photons with a "Light" touch

Mohammad Mirhosseini Institute of Optics @ the University of Rochester
Wednesday, November 19, 2014


Wednesday, October 22, 2014

How much information can a photon hold?


Photons After Dark

How much information can a photon hold?

Wednesday, October 22, 2014


Wednesday, September 17, 2014

A New Spin on Atom Optics: A Waveplate for Atoms

Justin T. Schultz Institute of Optics @ the University of Rochester

Photons After Dark

A New Spin on Atom Optics: A Waveplate for Atoms

Justin T. Schultz Institute of Optics @ the University of Rochester
Wednesday, September 17, 2014


Tuesday, April 19, 2016

Spintronics: Fundamentals and Applications

Alex Matos Abiague SUNY Buffalo

Physics Colloquium

Spintronics: Fundamentals and Applications

Alex Matos Abiague SUNY Buffalo
Tuesday, April 19, 2016

The need for faster, more powerful and yet more efficient devices has led to the emergence of Spintronics (or spin electronics) as an alternative to conventional electronics. Unlike conventional electronic devices, which rely on the transport of electrical charge carriers, spintronic devices use electron spins for building operational functionalities such as nonvolatile information storage, sensing, and logics. Typically, spins are manipulated by external magnetic fields, but solid state materials offer a great potential for all-electric spin manipulation by means of effective, momentum-dependent “magnetic” fields, the so-called spin-orbit fields. Those fields account for spin-orbit interactions and can be exceptionally large in some materials, which, as a consequence, exhibit exotic topological properties.
This talk will focus on the physical origin, characterization, and engineering of interfacial and synthetic spin-orbit fields and their effects on anisotropic magnetoresistive phenomena and topological quantum matter. Key implications of spin-orbit-mediated transport for a new generation of nonvolatile devices, as well as present challenges in their way to applications will also be addressed.

Thursday, April 14, 2016

Rational design of electrode materials for energy storage

Roberto Longo Pazos University of Texas, Dallas

Physics Colloquium

Rational design of electrode materials for energy storage

Roberto Longo Pazos University of Texas, Dallas
Thursday, April 14, 2016

For over 20 years, Li-ion batteries have enabled the rise of portable electronics, dominating the battery market. Current Li-ion batteries use layered oxides as cathode materials, specially LiCoO2, organic liquid electrolytes and graphite as anode. However, Co layered oxides and organic liquid electrolytes suffer from certain instability at high operational temperatures and flammability, respectively. In this colloquium, using first principles density-functional theory, I will examine the main characteristics of the most promising alternatives for electrode and solid-electrolyte materials, suggesting suitable pathways to improve their conceptual design and performance, thus serving as design principles for future discovery of electrode materials. 


Wednesday, April 13, 2016

Spontaneous parametric down conversion with a depleted pump as an analogue for black hole evaporation/particle production

Paul Alsing Air Force Research Laboratory

Physics Colloquium

Spontaneous parametric down conversion with a depleted pump as an analogue for black hole evaporation/particle production

Paul Alsing Air Force Research Laboratory
Wednesday, April 13, 2016

In this talk, I argue that black hole evaporation/particle production has a very close analogy to the laboratory process of spontaneous parametric down conversion, when the laser pump source is allowed to deplete. I will first present an overview of the essential features of the Unruh and Hawking effect and its analogy to the quantum optical process of spontaneous parametric down conversion widely used in the field of quantum information science as a source of photon-based qubits. In the previous case, the pump is considered a constant (i.e. non-depleted). I will next discuss the case when the black hole is treated as a finite `pump' source which is allowed to deplete, hence modeling the processes of black hole evaporation and Hawking radiation production. This model reproduces essential features of the Page Information curves (conjectured by D. Page, 1993) which are widely believe to describe the rate at which information escapes from the black hole as it evaporates, as the Hawking radiation deviates at late times from the pure thermal spectrum characterized by early black hole evolution times. Further details of this work can be found in (i) P.M. Alsing: Class. & Quant. Grav. 32, 075010, (2015); (arXiv:1408.4491), and (ii) P.M. Alsing & M.L. Fanto: Class. & Quant. Grav. 33, 015005 (2016), (arXiv:1507.00429).


Wednesday, April 6, 2016

First-principles theory-driven materials design and innovation in all-solid-state batteries

Yan Wang MIT

Physics Colloquium

First-principles theory-driven materials design and innovation in all-solid-state batteries

Yan Wang MIT
Wednesday, April 6, 2016

Emergent energy technologies are critically limited by materials performance and therefore highly dependent on materials innovation. The efficient design and discovery of new functional materials with desired performance represent formidable challenges to materials scientists. The ability to accurately predict key materials properties using first-principles computational methods, even before the materials synthesis and characterization, has made virtual materials design a reality. However, successful computation-based materials design often requires theoretical insights on the appropriate descriptors (genes) for the identification of candidate materials. In this seminar, I will present our recent efforts in theory-driven materials design and innovation in lithium superionic conductors and all-solid-state batteries using the computational materials genome approach. I will share our research breakthrough in theoretical identification of the gene for good ionic conductors by revealing the fundamental relationship between structural topology and ionic transport. Furthermore, an accurate and efficient first-principles computational methodology has been developed to evaluate thermodynamic stability of the solid-state electrolyte against electrodes at the battery interfaces. These findings not only provide valuable insights towards the understanding of materials behaviors in discovered ionic conductors, but also serve as design principles for new ionic conducting materials and all-solid-state batteries. Finally I will give an outlook on the potential of computational materials design for novel energy technologies.

Wednesday, March 9, 2016

Thin-film Electronics by Spatial ALD: Achieving High Performance with Low Process Complexity

Shelby F. Nelson Eastman Kodak Company

Physics Colloquium

Thin-film Electronics by Spatial ALD: Achieving High Performance with Low Process Complexity

Shelby F. Nelson Eastman Kodak Company
Wednesday, March 9, 2016

Patterning thin-film transistors for “printed electronics” applications can be challenging both for resolution and for alignment accuracy. This is particularly true for high-performance devices with submicron channel lengths, and for diverse and deformable substrates. Printing organic-based devices has additional issues such as printing dynamics, and orthogonality of solvents.  In this talk, I will describe alternative approaches to scalable thin-film electronics based on spatial atomic layer deposition (SALD) of metal oxides. Using the relatively high deposition speed of SALD, the conformality of the deposited layers, and the surface-sensitivity of the technique, we have explored both print-compatible high-performance vertical transistors, and patterned-by-printing circuitry. A reliable ZnO mobility above 10 cm2/Vs, on-off ratio above 107, and uniform threshold voltage values across the substrate give these approaches promise for large-area applications.


Wednesday, February 24, 2016

The Dawn of Gravitational Wave Astronomy

John T. Whelan RIT School of Mathematical Sciences and Center for Computational Relativity and Gravitation

Physics Colloquium

The Dawn of Gravitational Wave Astronomy

John T. Whelan RIT School of Mathematical Sciences and Center for Computational Relativity and Gravitation
Wednesday, February 24, 2016

Gravitational waves are ripples in the geometry of space and time which propagate at the speed of light, predicted by Einstein's General Theory of Relativity. Last fall, the Advanced LIGO detectors in Louisiana and Washington State began their first observing run, resulting in the recently reported first direct detection of gravitational waves, from a binary black hole inspiral, merger and ringdown. This first gravitational wave observation kicks off the field of Gravitational Wave Astronomy. I will present an overview of: 1) the science done so far with detectors such as LIGO and the Virgo and GEO600 detectors in Italy and Germany, 2) the most promising prospects for future observations with Advanced LIGO, Advanced Virgo, and planned detectors such as KAGRA (Japan) and LIGO India, and 3) the involvement of RIT scientists in the gravitational-wave enterprise.

Wednesday, December 2, 2015

The benefits of low permeability in articular cartilage

Mark Buckley University of Rochester

Physics Colloquium

The benefits of low permeability in articular cartilage

Mark Buckley University of Rochester
Wednesday, December 2, 2015

Abstract: Articular cartilage is a durable, load-bearing, poroelastic tissue that coats bones in joints and protects them from damage over several decades. Unfortunately, trauma-induced cartilage cell (chondrocyte) death can initiate a cascade of degradative alterations in the joint. In this talk, I will discuss how a key property of articular cartilage – its hydraulic permeability – mediates its ability to withstand extreme forces in two distinct ways. First, since exudation of fluid facilitates tissue compression, low permeability delays tissue deformation and allows chondrocytes to survive brief periods under extreme loads that would otherwise be fatal. Second, because permeability is low in articular cartilage and further decreased when the tissue is compressed, harmful intracellular contents that are released in areas where cell death occurs always flow towards the point of contact rather than towards healthy, uninjured cells. This protective feature could prevent the spread of cell death and contribute to the durability of articular cartilage. Finally, I will discuss a separate phenomenon related to cartilage longevity that our experiments have recently revealed: the ability of chondrocytes to adapt to recently imposed physical forces and thereby become less susceptible to subsequent mechanical injury. 


Wednesday, November 4, 2015

Unexpected ordered phases in active systems

Michael Hagan Brandeis University

Physics Colloquium

Unexpected ordered phases in active systems

Michael Hagan Brandeis University
Wednesday, November 4, 2015

Active matter describes systems whose constituent elements consume energy to generate motion or forces. Since these systems are intrinsically nonequilibrium, they can exhibit collective behaviors unlike anything possible in a traditional equilibrium material. In this talk I will describe computer simulations of two recently developed model active matter systems,  self-propelled colloidal particles and extensile active nematics, and unexpected ordered phases that arise as a consequence of activity in these systems.

When colloidal particles are asymmetrically coated with a catalyst and placed in the presence of a fuel, they undergo directed motion. An idealized model for such particles, self-propelled spheres with repulsive interactions and no aligning interactions, has become an intensely studied theoretical and computational model system. We and others have recently shown that this system undergoes a continuous phase transition analogous to that of equilibrium systems with attractive interactions. Particles in the dense phase form ‘active crystals’ with hexatic or crystalline order but efficient transport properties. I will discuss some new features of this system; then, I will show that when these particles are confined they undergo another transition, in which the particles become confined to the boundary, with a density that depends on the local curvature radius of the boundary.  A theory describing this behavior allows designing boundary shapes that lead to a wide variety of particle density distributions.

Active nematics are liquid crystals which are driven out of equilibrium by energy-dissipating active stresses.  The ordered nematic state is unstable in these materials, due to the spontaneous generation of topological defects, which undergo birth, streaming dynamics, and annihilation to yield a complex, seemingly chaotic dynamical steady-state.  In this talk, I will show that order emerges from this chaos, in the form of heretofore unknown broken-symmetry phases in which the topological defects themselves undergo orientational ordering. I will describe the appearance of these phases into realizations of an active nematic: (1) an experimental system containing extensile bundled microtubules and molecular motor proteins studied by the Dogic lab at Brandeis, and (2) a computational model of extending hard rods.  I will describe the defect-stabilized phase that manifests in each system and our current understanding of their origins.  Such phases may be a general feature of extensile active nematics.


Wednesday, October 14, 2015

Pentaquarks: Quark Model Revisited

Tomasz Skwarnicki Syracuse University

Physics Colloquium

Pentaquarks: Quark Model Revisited

Tomasz Skwarnicki Syracuse University
Wednesday, October 14, 2015

 The LHCb experiment has recently reported the observation of pentaquark candidates: bound states of four quarks and an antiquark. Such objects have been predicted for over 50 years, but until recently believed not to exist. I will describe the bumpy road which led to this recent observation, starting from the birth of the Quark Model, through its spectacular success in describing known mesons and baryons and searches for quark structures made out of more than the minimal quark content. I will describe the LHCb pentaquark measurement and conclude with implications of the recent observations of tetraquark and pentaquark candidates on our understanding of the fabric of matter made out of quarks.
 

Wednesday, September 30, 2015

Shearing While Looking at Nonlinear Soft Materials

Daniel Blair Georgetown University

Physics Colloquium

Shearing While Looking at Nonlinear Soft Materials

Daniel Blair Georgetown University
Wednesday, September 30, 2015


Wednesday, September 9, 2015

Physics Colloquium: Summer REUs

Tyler Godat, John Collini, & Luke Shadler RIT Physics Majors

Physics Colloquium

Physics Colloquium: Summer REUs

Tyler Godat, John Collini, & Luke Shadler RIT Physics Majors
Wednesday, September 9, 2015


Wednesday, April 15, 2015

Breaking The Myth of the "Non-Traditional" Physicist: The Real Story About Employment for Physics Graduates

Crystal Bailey American Physical Society (APS)

Physics Colloquium

Breaking The Myth of the "Non-Traditional" Physicist: The Real Story About Employment for Physics Graduates

Crystal Bailey American Physical Society (APS)
Wednesday, April 15, 2015


Monday, March 2, 2015

Characterizing Exoplanet Atmospheres through Our Own

Sloane Wiktorowicz University of California, Santa Cruz

Physics Colloquium

Characterizing Exoplanet Atmospheres through Our Own

Sloane Wiktorowicz University of California, Santa Cruz
Monday, March 2, 2015


Friday, February 12, 2016

Observation of Gravitational Waves from a Binary Black Hole Merger

John Whelan, Richard O'Shaughnessy, Carlos Lousto, and Manuella Campanelli CCRG

CCRG seminar

Observation of Gravitational Waves from a Binary Black Hole Merger

John Whelan, Richard O'Shaughnessy, Carlos Lousto, and Manuella Campanelli CCRG
Friday, February 12, 2016

Abstract:
LIGO has just reported three discoveries: the first direct detection of gravitational waves; the discovery of a binary black hole; and the observation of gravitational waves from this binary's coalescence,  in excellent agreement with Einstein's theory of gravity.  In a presentation and panel discussion, RIT scientists John Whelan, Richard O'Shaughnessy, Carlos Lousto, and Manuella Campanelli -- all members of RIT's Center for Computational Relativity and Gravitation --  discuss the significance of these findings.

For more information see the attached summary PDF, and the summaries avaialble at
  -   http://ligo.org/science/outreach.php
  -   https://losc.ligo.org/events/GW150914/


Monday, December 7, 2015

Vibrations from the Big Bang

Jamie Bock California Institute of Technology

Distinguished Speaker

Vibrations from the Big Bang

Jamie Bock California Institute of Technology
Monday, December 7, 2015

Moments after the Big Bang, our observable universe underwent a violent growth spurt called inflation. The inflationary expansion flung apart the observable universe from a causally-connected sub-atomic volume, and established a primordial spectrum of scalar perturbations that led to the temperature anisotropies observed in the cosmic microwave background. Dr. Bock's team has been making precise degree-scale polarization measurements of the CMB from the south pole with the BICEP/Keck series of experiments in search of a distinctive ‘B-mode’ pattern, a hallmark of tensor perturbations associated with a background of gravitational waves generated by inflation. Dr. Bock will present our latest results that incorporate multi-band information from the Planck satellite and new Keck Array data at 95 and 150 GHz. He will also discuss prospects from new data and improved measurements coming in the near future.

Supported by the John Wiley Jones Science Endowment Fund
To request Interpreting Services, please visit myAccess.rit.edu.


Friday, September 11, 2015

Listening for Deep Understanding of Energy

DR. MICHAEL WITTMANN University of Maine

CASTLE Seminar

Listening for Deep Understanding of Energy

DR. MICHAEL WITTMANN University of Maine
Friday, September 11, 2015

How do people understand energy? In studying teaching and learning in physics, researchers have primarily used two methods to understand content understanding: individual interviews or large-class surveys. Sometimes it's not possible to do either, given constraints on the population being interviewed, or a small enough population that the statistics from surveys won't tell us much. In the Maine Physical Sciences Partnership, we have addressed this problem in two ways when working with the population of middle school physical science teachers. We have asked them survey questions on an annual basis and can use the changes in their responses to investigate their thinking about energy. We have also observed and analyzed their interactions in large-group discussion during professional development activities. By listening differently, we're able to learn about their knowledge of the deep structure of the physics.


Wednesday, May 6, 2015

From Exoplanets to Exoworlds

David Rosario Max Planck Institute for Extraterrestrial Physics

Seminar

From Exoplanets to Exoworlds

David Rosario Max Planck Institute for Extraterrestrial Physics
Wednesday, May 6, 2015


Friday, May 1, 2015

How Cosmic Collisions Shape the Universe

Jeyhan Kartaltepe National Optical Astronomy Observatory

Seminar

How Cosmic Collisions Shape the Universe

Jeyhan Kartaltepe National Optical Astronomy Observatory
Friday, May 1, 2015


Wednesday, April 29, 2015

From Exoplanets to Exoworlds

Kevin Stevenson University of Chicago

Seminar

From Exoplanets to Exoworlds

Kevin Stevenson University of Chicago
Wednesday, April 29, 2015


Rochester Institute of Technology College of Science