Jacob Moldenhaur Ph.D.

EDUCATION
Ph.D., University of Texas at Dallas
M.S., University of Texas at Dallas
B.A., University of the Ozarks

RECENT COURSES
General Physics I and II and Labs
Physics and Technology and Lab
Introduction to Astronomy and Lab
Astrophysics and Cosmology
General Relativity
Statistical Physics
Theoretical Mechanics
Electrodynamics
Electronics and Lab
Optics and Lab
Quantum Physics Lab
Physics Seminar

RESEARCH INTERESTS
My research is in theoretical cosmology using analytical and numerical calculations, which involve the use of available data from NASA and other international databases.  I use computational resources such as high performance computing clusters, sophisticated numerical algorithms and interactive simulations all integrated with recent observational data sets to pursue answers to some of the most compelling and still-lingering questions about the universe.  How old is the universe?  When and how did it begin?  Was there something before the Big Bang?  What is the cause of the current accelerated expansion of the universe (also called the cosmic acceleration)?  What size and shape is the universe?  What is the ultimate fate of the universe?  Most of my current work involves determining the cause of the cosmic acceleration. As the universe expands, other galaxies accelerate away from us. Physicists do not yet know the cause of this accelerated expansion.  It could be due to some form of as of yet unknown dark energy, i.e. Cosmological Constant, requiring a negative pressure and negative equation of state.  Another popular explanation for the cosmic acceleration comes from extensions to the theory of general relativity that take effect at cosmological scales of distances, e.g. modified gravity.  An important part of this project involves being able to observationally distinguish between these different theories and perform tests to falsify them.  I explored and falsified many modified gravity models in my dissertation, Dynamics and Phenomenology of Higher Order Gravity Cosmological Models, and we developed parameterizations to falsify general relativity at cosmological scales with the Integrated Software in Testing General Relativity (ISiTGR), which will prove very useful as more precise data becomes available over the next few years. 

Specifically, I test cosmological models against experimental data sets.  Constraints on parameter values in the models will either support or rule out the theory behind the model.  It is my desire, not only to answer some of these questions, but also be able to allow non-cosmologists to understand the explanations and cosmological methodologies.  So, I also focus some of my time on cosmology education research.  I began constructing cosmological modeling simulations with the help of Easy Java Simulations (EJS) in collaboration with my colleagues at Francis Marion University (FMU) and most recently at the University of Dallas (UD).  These simulations are packaged as CosmoEJS, an interactive cosmology simulation that allows users to fit cosmological models to actual data sets using EJS. These simulations combine real-time plotting and numerical fitting to illustrate how theoretical models can be compared with experimental data sets to test a cosmological model.  The simulations contain genuine data sets from recent cosmological surveys with options for testing more than one model at a time for easy visual and numerical comparisons.  The visual comparisons allow users to directly see why some models match the data and others do not, while the numerical comparisons are for refining the parameter values for a best-fit model.  Several colleagues at the Fall 2014 Meeting of the Texas Section of the American Physical Society (TSAPS) remarked that these programs were exactly what they were looking for in the field of cosmology.  More information on these simulations  can be found in our articles, Modern Cosmology:  Interactive Computer Simulations using Recent Observational Data Sets, (Am. Jour. Phys., Vol. 81, Issue 6, 2013) and Exploring the constraints on cosmological models using CosmoEJS, (JCAP11(2018)011).  (Both projects were completed with undergraduate students.) 

At the 2019 Texas Symposium on Relativistic Astrophysics in Portsmouth, England, I presented a 30 minute talk on this work on CosmoEJS. This work was recently highlighted with the 2019 Nobel Prize in Physics. In the announcement of the Nobel Prize in Physics by the American Journal of Physics (AJP), our original CosmoEJS article in AJP is given as one of three Top Articles in Cosmology, along with those of the Nobel Laureate for content related to the 2019 Nobel Prize in Physics.

This is an exceptional arena from which undergraduates new to cosmology can begin their study because in addition to learning about the subject matter, they also help to develop tools for their peers.  I had undergraduate students during my two years at FMU and continue to work with undergraduate students at UD in the past years contribute to these projects by adding a new simulations for new cosmological observations, as well as new functionalities for these programs.  Once they become familiar with the material, they are better prepared to understand the theoretical research, which involves not only knowing the observations, but also how the theoretical models are constructed.  We also make use of the simulations in the classroom and education outreach, like astronomy club.  I have my students present their program to a non-majors class for the opportunity to try out their tools on audiences less familiar with the work.  This gives them a chance not only to demonstrate their understanding, but also improves their ability to communicate about the field with their peers. 

Undergraduate students with the desire to explore cosmological questions learn High Performance Computing (HPC) skills to test cosmological models with observational data sets.  These tests are performed using a modified version of the publicly available Monte Carlo Markov Chain code for cosmology,cosmoMC, (A. Lewis and S. Bridle, Phys. Rev. D66, 2002).  This code is used along with certain packages, or modules like ISiTGR, (J. Dossett, M. Ishak and JM, Phys. Rev. D84, 2011) designed to test for consistency with general relativity using elegant parameterizations for modeling the dark energy at different times in the universes evolution.  My students and I collaborate with a group at The University of Texas at Dallas, DARKLIGHT Group Osservatorio Astronomico di Brera and also use the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for running these tests, and we have our own cluster of computing nodes on the UD campus.   In all cases, not only do the students learn how to use HPC to efficiently test dark energy models, but they also learned about HPC in general through usage and design of an instructive computing cluster built by the students from repurposed materials in the department.  In order to bridge the gap between undergraduate education and research, undergraduates need experience in HPC.  Beyond simply logging into a remote terminal, truly understanding HPC is particularly difficult for undergraduate students because the HPC cluster consisting of large machines locked-away in secure datacenters, offers few opportunities for students to grasp the totality of HPC systems.  A hands-on experience is critical to filling in the gaps in their understanding.

In addition to my cosmology research, I have interdisciplinary projects with the UD Biology Department. We have successfully developed a novel physical model of the human head and brain for studying concussive and sub-concussive level collisions. There is also new work with Dr. Stenesen on developing methods to detect the electrical signal in the eye of a fruit fly and image structures using the Atomic Force Microscope and X-ray Computed Tomography (CT) scans, see the work on the student research webpage.

PEER-REVIEWED PUBLICATIONS

1. “Exploring the constraints on cosmological models using CosmoEJS,” JM, Francis Cavanna, William O’toole, William Zimmerman, JCAP11(2018)011, arxiv:1801.01781.
   
2. “The Cosmic Acceleration of the Universe Lab using CosmoEJS Package” by JM, Open Source Physics Lab (2018). Open Source Physics website.
3. Modern Cosmology: Interactive Computer Simulations using Recent Observational Data Sets, JM, Larry Engelhardt, Keenan Stone, Ezekiel Shuler, Am. Jour. Phys., Vol. 81, Issue 6, 2013
4. Testing General Relativity at Cosmological Scales: Implementation and Parameter Correlations, formerly, Testing General Relativity at Cosmological Scales using ISiTGR, Jason Dossett, Mustapha Ishak, JM, Phys. Rev. D, October 2011, arxiv:1109.4583.
5. Supernova, BAO, and CMB surface distance constraints on f(G) higher order gravity models, JM, Mustapha Ishak, John Thompson, Damien Easson, Phys.Rev.D81:063514,(2010), arxiv:1004.2459.
6. A minimal set of invariants as a systematic approach to higher order gravity models: Physical and Cosmological Constraints, JM, Mustapha Ishak, JCAP 0912:020 (2009) arxiv:0912.5332.
7. A New Independent Limit on the Cosmological Constant/Dark Energy from the Relativistic Bending of Light by Galaxies and Clusters of Galaxies, Mustapha Ishak, Wolfgang Rindler, Jason Dossett, JM, Chris Allison, MNRAS 388, 1279-1283 (2008), arxiv:0710.4726.

PRESENTATIONS
Texas Symposium on Relativistic Astrophysics Meeting, 30-minute Contributed Talk: “Exploring the Hubble Constant Tension with CosmoEJS”, JM, December 16, 2019, Portsmouth England

Physics Colloquium Space Week, Dallas County Community College Mountain View Campus, Invited Talk: “Gravitational Waves, Dark Matter, Dark Energy: Recent Success and Shortcomings of General Relativity”, JM, October 7, 2019

Testing Gravity Meeting, Contributed poster, The dynamics of cosmological models using CosmoEJS”, JM, January 17, 2019

Physics Colloquium Space Week, Dallas County Community College Mountain View Campus, Invited Talk: “Gravitational Waves, Dark Matter, Dark Energy: Recent Success and Shortcomings of General Relativity”, JM, October 10, 2018

American Physical Society April Meeting, Contributed Talk: “The dynamics of cosmological models using CosmoEJS”, JM, Andrew Chang, April 16, 2018, Columbus, OH

TSAPS, San Antonio College, Contributed Talk: “Translational and Angular accelerations measured inside a novel, physical model of a human head”, JM, Stephen Slaughter, Cora Keil, Sydney McCloskey, Andrew Chang, James Frisby, March 9, 2017, San Antonio, TX

Physics Colloquium, Dallas County Community College Mountain View Campus, Invited Talk: “Gravitational Waves, Dark Matter, Dark Energy: Recent Success and Shortcomings of General Relativity”, JM, November 3, 2016, Dallas, TX

Physics Colloquium, The University of Texas at Dallas, Invited Talk: “Computational Cosmology: What can models and simulations teach us about the universe?”, JM, April 13, 2016, Richardson, TX

Physics Colloquium, Dallas County Community College Richland Campus, Invited Talk: “Gravitational Waves, Dark Matter, Dark Energy: Recent Success and Shortcomings of General Relativity”, JM, March 4, 2016, Richardson, TX

Physics Colloquium, Dallas County Community College Mountain View Campus, Invited Talk: “Gravitational Waves, Dark Matter, Dark Energy: Recent Success and Shortcomings of General Relativity”, JM, March 3, 2016, Dallas, TX

Texas Symposium on Relativistic Astrophysics, Talk and poster presentation: “Exploring the consequences of parameter values in cosmological models with CosmoEJS, an interactive package of cosmology Java simulations”, JM, Francis Cavanna, William O’toole, William Zimmerman, Geneva, Switzerland, December 13-18, 2015

Texas Section APS Meeting, Talk: “Investigating cosmological parameters using CosmoEJS, an interactive package of cosmology Java simulations”, JM, Francis Cavanna, William O’toole, William Zimmerman, University of Baylor, Waco, TX, October 29-31, 2015

Testing Gravity 2015, Talk: Interactive Testing of Cosmological Models Using the Latest Data Sets in the CosmoEJS Package, JM, William Zimmerman (UD student), Vancouver, BC, January 14-17, 2015.

Texas Section APS Meeting, Talk: Interactive Cosmological Modeling with Easy Java Simulations: Constraints from a New Growth of Structure Module of CosmoEJS, JM, William Zimmerman (UD Student), College Station, TX, October 17-19, 2014.

Collin College Undergraduate Interdisciplinary Student Research Conference, Sponsored senior thesis presentation, Hawking Radiation: The Black Hole Destroyer, Aaron Stolle (UD student), Jacob Moldenhauer, Plano, TX, April 16-17, 2014.

50th Texas Symposium for Relativity and Astrophysics, Poster: Interactive Cosmological Modeling with Easy Java Simulations, Dallas, TX, December 8-13, 2013.

American Astronomical Society 221 Winter meeting, Talk: Interactive Cosmological Data Fitting Simulations: A Further Examination of CosmoEJS, JM, & Sponsored student poster on interactive computer simulations for cosmology, Poster: Modifications to CosmoEJS, Keenan Stone, Ezekiel Shuler, JM, Long Beach, CA, January 6-10, 2013.