"Physics is the only profession in which prophecy is not only accurate but routine."
- Neil deGrasse Tyson
Physics majors enjoy discovering how things happen and speculating about why things happen. They learn to approach new problems confidently—to identify general features of these problems, apply appropriate methods to their solutions, and communicate the consequences of such solutions effectively. Many of our students may not become professional physicists, but they will be able to apply their problem-solving skills in any career.
The physics major at Bowdoin includes a rigorous introduction to the mathematics and physics common to all subfields of physics within the framework of a strong liberal arts education. Students should include upper-level courses in the humanities as well as upper-level courses in mathematics and physics in their studies. A strong preparation for advanced work, coupled with general intellectual growth and good scholarship, is our goal.
Title: Direct millicharged dark matter cannot explain EDGES
Speaker: Cyril Creque-Sarbinowski, Johns Hopkins University
Spacetime coordinates: Monday, November 25, 2019 at 3:00 p.m. in Searles 315
Heat transfer between baryons and millicharged dark matter has been invoked as a possible explanation for the anomalous 21-cm absorption signal seen by EDGES. Prior work has shown that the solution requires that millicharged particles make up only a fraction of the dark matter and have mass and charge within a certain range. Here we show that such particles come into chemical equilibrium before recombination, and so are subject to a constraint on the effective number of relativistic degrees of freedom, which we update using Planck 2018 data. We moreover determine the precise relic abundance f that results for a given mass and charge and incorporate this abundance into the constraints on the millicharged-dark-matter solution to EDGES. With these two results, the solution is ruled out if the relic abundance is set by freeze-out.
Date: Wednesday, October 30, 2019
Time: 4:30 PM
Location: Searles 315
Speaker: Dale Kocevski - Department of Physics and Astronomy, Colby College
Illuminating the Black Hole – Galaxy Connection
Supermassive black holes, and the active galactic nuclei (AGN) that they power, are thought to play an integral role in the evolution of galaxies by acting to regulate, and eventually suppress, the star formation activity of their host galaxies. I will discuss recent efforts to test this proposed connection by studying the demographics of galaxies undergoing active black hole growth. In particular, I will highlight results from the CANDELS survey, which has used infrared imaging from the Hubble Space Telescope to study of properties of galaxy back when the Universe was a quarter of its current age. It is during this era of cosmic history that black hole growth and star formation activity in the Universe are at their peak. I will discuss what CANDELS is currently revealing about the mechanisms that fuel AGN activity at this epoch and the connection between black hole growth and the emergence of the first generation of passive galaxies in the Universe.
Both by Professor Richard Alley:
Thursday, October 10th. 12:00pm Searles 315
Research seminar: “Falling Dominoes: Ice Sheets and Sea Level”
Thursday, October 10th. 7:30pm Smith Auditorium, Sills Hall
Public lecture: “Climate has always changed naturally”—How climate history increases concerns about fossil-fuel burning
Professor Richard Alley is this year’s Carl F. Cranor Visiting Scholar. Support for his visit is provided by Phi Beta Kappa Society and Bowdoin’s Kibbe Science Lecture Fund.
Richard Alley is Evan Pugh University Professor of Geosciences at Penn State. He studies the great ice sheets to help predict future changes in climate and sea level, including multiple trips to Antarctica, Greenland, Alaska, and elsewhere. He has been honored for research (including election to the US National Academy of Sciences and Foreign Membership in the Royal Society), teaching, and service. Dr. Alley participated in the UN Intergovernmental Panel on Climate Change (co-recipient of the 2007 Nobel Peace Prize), and has provided requested advice to numerous government officials in multiple administrations. He has authored or coauthored over 300 refereed scientific papers. He was presenter for the PBS TV miniseries on climate and energy Earth: The Operators’ Manual, and author of the book. His popular account of climate change and ice cores, The Two-Mile Time Machine, won the Phi Beta Kappa Award in Science.
Septermber 27, 2019
Margaret Geller - Caught in the Cosmic Web
Join Margaret Geller for a journey through the universe. Throughout her career, she has been caught in the cosmic web, the largest pattern we know in nature. She will describe her role in discovering these patterns in the nearby universe and her ongoing work to map the way they evolve over the last eight gigayears of cosmic history
September 26, 2019
Scott Kenyon - Pluto Strikes Back!
Abstract: Over a decade ago, astronomers decided to demote Pluto as a planet and call it a ‘dwarf planet’. After a brief summary of Pluto’s discovery and demotion, I will discuss the amazing discoveries about Pluto we have made in the last 15 years and describe how Pluto provides important information on how much larger planets form around other stars.