United States

We analyze models of decaying dark matter, searching for shifts in $H_0$ and $\sigma_8$ to resolve the tensions between linear and astrophysical measurements. While previous searches have focused on dark matter with lifetimes on the order of the current Hubble time, we instead consider dark matter that decays between the time of last scattering and the era of large scale structure. We find that while decaying dark matter pushes parameter likelihoods in the right direction to resolve the Hubble Tension, the bounds ($\Omega$ = 0 to 10^-2 for lifetimes a tenth of the Hubble Time) on decaying dark matter are too strong to resolve the tension completely, a conclusion unchanged even when spatial curvature is allowed to vary. In addition, these bounds can be used to constrain theoretical models such as coupled axions from string compactifications.

AAPT WM 21

The Effects of Decaying Dark Matter on The Hubble Constant

cosmology

dark matter

hubble tension

**WELCOME TO THE 2021 CAP VIRTUAL CONGRESS UNDERLINE PLATFORM**

The CAP staff and our organizing and program committees are pleased to welcome you to our 2021 Congress filled with plenary talks, technical sessions/talks, student presentations and competition sessions, workshops, and several symposia offered by the CAP divisions and its partners.  

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CAP Virtual Congress 2021

technical paper

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As a part of our larger research on students’ conceptions on fluids, our group has been developing a taxonomy categorizing alternate conceptions about buoyancy and giving assessments in various introductory courses to determine the prevalence of selected taxonomy items.&nbsp; Along with this, we are analyzing student understanding of the constructs, or core ideas, that are necessary for understanding buoyancy. &nbsp;In this poster, we describe a few selected assessment questions focusing on the volume of fluid displaced and the relationship between buoyant force and pressure and the constructs they probe, and we compare the most prevalent distractors to their corresponding alternate conception.

Probing Understanding of Buoyant Force and Volume of Fluid Displaced

QuarkNet has created workshops for its member teachers based on actual particle physics data. One great source of that data is the Large Hadron Collider (LHC) at CERN. In an LHC Data Workshop, teachers build up to an authentic LHC data analysis experience by trying out and reflecting on activities from the QuarkNet Data Activities Portfolio, which themselves often involve LHC data. All of these can be shared with their students. We will examine LHC Data Workshops, how teachers can get involved, and how the model can be used in teacher professional development.

QuarkNet LHC Data Workshops

QuarkNet High School students and teachers have collected data on cosmic ray muons. Their data is available to all on the i2u2.org site and enable measurements of fundamental particle properties.&nbsp;&nbsp;High school and university users can also request groups to modify detector setups in order to collect customized data. Some QuarkNet high school groups have also carried out several more complex projects, e.g. Solar Eclipse 2017, MUSE at Fermilab, and storm tracking, that required assembling an entire particle physics collaboration.

QuarkNet High School Cosmic Ray Projects

Positive attitude is&nbsp;important in learning physics. Students and teachers can have fun together inside and outside classrooms.&nbsp;

Improving Positive Attitude in Learning Physics

This presentation will provide an overview of presentations that will be available to those attending for use with their classes.The presentations are intended for use with students in grades 6-9, 10-12, and introductory college classes. Climate science challenges are presented in terms of entropy changes that occur due to procuring and burning fossil fuels to produce electricity. Infromation about the Climate Reality Project is also included.

A Thermodynamic approach to Climate Science

What is science?&nbsp; What are the psychological, economic, and political factors that shape people's decisions about truth or fact?&nbsp; Do truth, facts, or opinions guide science and technology policies?&nbsp; These are the questions we address in a one credit seminar for first-year students.&nbsp; The seminars were developed as part of Spelman College’s Big Questions Colloquia, and they cover many different areas. &nbsp;In this seminar, students learn about how people reason and what science is. Eventually, students build skills to help them critique policies and differentiate between science and pseudoscience.&nbsp; We explore controversial topics like big tobacco, and look at some conspiracy theories, such as the Apollo hoax. From the seminar, students gain experience critiquing, evaluating, and thinking about science and related policies.&nbsp; I will present my experiences with developing the seminar, and some strategies for building an interdisciplinary approach to communicating about science.

An Interdisciplinary Seminar on Knowledge, Science, and Policy

Galileo’s trial in 1633 was not the cultural myth of rational science versus irrational religion but rather a notable flashpoint in possibly the most significant cultural paradigm shift in western history.&nbsp; Galileo, colleagues and opponents clashed over metaphysics, epistemology, theology, tradition and even experimental science against a backdrop of armed conflict, religious battles, globalization, nationalism, economic change, information revolution and a reoccurring pandemic—not so different from today.&nbsp; In many respects the geocentric versus heliocentric battle was the premiere socio-scientific conflict which helped shape the emergence of modern science, making it a valuable and (no longer controversial!) case study to help better understand contemporary ones.&nbsp; This talk will describe a new course in which we first study Galileo to understand the nature of science and the many facets of socio-scientific conflicts— history, social identity, foundational assumptions, cognitive biases, conflict theory, rhetoric and argumentation—then apply that understanding to contemporary ones.

Studying the Past to Understand the Present

The air we breathe is constantly changing. The dynamic nature of outdoor and indoor air makes it interesting to measure. There are many natural opportunities in an intro electromagnetism course for students and professors to observe how quantities like carbon dioxide, methane, and particulate matter change over time. We will look at a few sensors that measure various gases and particles in the air. Then we will discuss ideas for integrating them into the intro physics classroom. Understanding what influences the air gives students an interest in the atmosphere around them and offers them a chance to change it with their actions.

The Physics of Healthy Air

The campus shutdowns due to the pandemic posed a serious challenge to labs, especially advanced labs. We offer a lab component to our upper-level quantum mechanics course based on photon labs. We adjusted by setting our labs to be remotely operated. We automated the labs using USB-based rotating or translating mounts, which moved optical components. Arduino-based circuits allowed remote control of the equipment (laser and detectors) and data acquisition. A webcam gave a view of the apparatus. A student connected to other group members by zoom logged into the lab computer via remote PC, and screen-shared the remote-desktop view. The PC controlled the apparatus via serial-port windows. An advantage was that we needed only one setup, and students could pick a convenient time to do the lab. The lab instructor was available online for consultation. It lacked a hands-on component, but exposed students to troubleshooting remotely.

Remote Photon Quantum Mechanics Labs

Prior to March 2020, few introductory undergraduate physics laboratories were offered in the distance-learning format.&nbsp; This work follows a Summer talk describing new lab curriculum and research study for the emergency remote teaching environment of Spring 2020. Using pre/post-instruction surveys and analysis of lab reports/assignments, we assessed the impact of the curriculum on students. Here, we describe students’ attitudes toward the simulation-based and project-based components of the course as compared to in-person labs they experienced, previously.&nbsp; We also show that students experienced a gain in self-efficacy and favored some aspects of the course over others. Additionally, we found students spent more time on the assignments than anticipated. Students reported engaging with design and modelling skills through the do-it-yourself project, though reports sometimes lacked coherent design methodology or uncertainty analysis.&nbsp; Finally, we share our post-mortem analysis of the course features that contributed to these outcomes and future plans for this curriculum.

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