Weekly Colloquium

Most weeks during the semester, we host a scholar for a one-day visit. The visit culminates with a public talk on a topic of contemporary physics or astronomy. Students are welcome to these talks, and seniors are required to attend at least nine over the course of a year. Near the end of each semester, honors thesis students give public lectures on their work.  We gather before the talks for tea, coffee, and cookies at 3:45, Ground Lobby of Science Center followed by the talk at 4:00 pm in A011.

Our Astronomy program is part of the Five College Astronomy Department, which hosts its own colloquium series Thursdays at 3:45 pm at UMass in LGRT 1033. 

  • If you would like to be mailed seminar announcements, please send an email to physics@amherst.edu.
  • Contact colloquium organizer Alice Simmoneau (asimmoneau@amherst.edu) with any questions about colloquia.

February 2019

Tue, Feb 5, 2019

Associate Professor, Alex Pope, UMASS: "Rise of dust: Completing our Census of Cosmic Star Formation"

Observations at submillimeter/millimeter wavelengths provide a unique view of galaxy formation, revealing hidden star formation in the early Universe (a few Gyr after the Big Bang) that cannot be seen at optical wavelengths due to extreme dust obscuration. Previous surveys from single-dish telescopes were sensitive to only the most extreme galaxies forming stars >100 times the rate of the Milky Way, while the more typical galaxies that dominate the total energy budget at these wavelengths remain elusive. I will discuss recent observations of dusty galaxies with the next generation of (sub)millimeter wavelength telescopes – including the Large Millimeter Telescope (LMT) and the Atacama Large Millimeter Array (ALMA) – to push studies of dust-obscured activity down to the more typical galaxies that dominate the cosmic star formation history. Finally I will introduce TolTEC, a revolutionary new camera for the LMT, and the public legacy surveys that will be completed from 2019-2021. These surveys will make a complete census of dust-obscured activity in the Universe.

Tue, Feb 12, 2019

Assistant Professor Jinglei Ping, UMass Amherst: "¬2D-Material Biosensors"

The emerging field of biosensors based on two-dimensional (2D) materials offers a pathway to new opportunities in microbioanalytics, highlighting next-generation tools for point-of-care diagnostic, health care, and environmental monitoring. My talk will focus on the unique transduction properties of 2D materials and the downstream biomolecular-sensor applications with unprecedented high sensitivity and efficiency in power, size and cost. I will discuss the self-transducibility of 2D materials at the interface to biofluids; the methodologies I developed to fabricate, functionalize and implement small-scale (~ ????m) 2D-based biosensing devices; and label-free detection of various biomarkers (nucleic acid oligomers, proteinaceous antigens, opioid-neuropeptides, pH) with high sensitivity, e.g. attomolar for DNA, by using the devices. I will conclude by introducing a handheld multiplexed water-quality monitoring robot enabled by graphene aptasensors.

Tue, Feb 19, 2019

Professor James Valles, Brown : "Learning about Life in High Magnetic Fields"

Anyone that has held a strong magnet knows intuitively that living materials are barely affected by magnetic fields. Electric and gravity fields, by contrast, are known to exert a strong influence on our bodys’ functions. Despite their relative weakness, researchers have been exploiting the unique properties of magnetic fields to probe biological systems. Superconducting solenoids and resistive magnets at international facilities can generate static fields that are sufficiently intense to align biopolymers such as microtubules and biomolecular assemblies such as cell membranes. Moreover, common organic materials can be magnetically levitated. We are exploiting these weak intrinsic responses to manipulate cellular processes. I will describe our work on few systems. We have found that magnetic fields alter the geometry of the early cell divisions of frog eggs. Our efforts to determine the mechanism have led to new insight into the factors that control the nominal cell division geometry. More recently, we have applied magnetic forces and torques on the swimming single-cell organism, Paramecium, which substantially change its swimming direction and speed. I will describe our efforts to use these effects to study the origins of its remarkable sensitivity to the body force of gravity.

Tue, Feb 26, 2019

Associate Professor Takeuchi Tatsu, Virginia Tech: "Proposal of a New Terminology for Newton's Third Law: From Force-centric to Momentum-centric Pedagogy of Newton's Laws"

Newton's Third Law, aka the action-reaction law, can be quite confusing to many students, instructors and even to some textbook writers as well. The main reason for this is the unfortunate choice of terminology by Newton in his Principia. Many people think that what Newton meant by "reaction" is the reaction to "action" (which it isn't), and this misunderstanding is prevalent not only in the classroom but in popular media as well. I propose that even though "action" and "reaction" are the terms used by Newton himself (they are the same in Latin), it is high time we abandoned them for better ones that would aid in our own and our students' understanding. I will present my own proposal in this talk, though I suspect there may be better ones, and also propose a new pedagogy which emphasizes the concept of momentum above force in teaching Newton's Laws.