The Ten Most Popular Physics Today Articles of the Spring and Summer Quarantine

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The Ten Most Popular Physics Today Articles of the Spring and Summer Quarantine


Mikayla Cleaver, SPS Programs Coordinator

The Advanced Photon Source (APS) at Argonne National Laboratory (ANL). Photo courtesy of

1. “Graduate Departments Move Away from GREs,” by Dalmeet Singh Chawla, July 9, 2020

The general Graduate Record Examinations (GREs) and GRE subject tests in physics have slowly been disappearing from the requirements of physics and astronomy graduate programs. With the COVID-19 pandemic, additional departments are joining this trend for the short term, and some are considering making the change permanent. Research has highlighted issues with using these standardized tests—notably, their inability to predict student success in graduate programs and their tendency to introduce inequities in the admissions process. The cost of testing, access to testing locations, and other factors can serve as barriers for very capable students, making it hard for them to do well or even take the test. Students can take the test at home during the pandemic but may still struggle with the cost, finding a quiet place to take the test, and having reliable internet access, among other concerns. Eliminating these tests may result in physics and astronomy departments seeing a more diverse and better-quality graduate student class.

2. “Helium Shortage has Ended, for Now,” by David Kramer, June 5, 202

In addition to birthday parties, helium is a key element in medical research, scientific research, industrial processes, and medical treatments, among other applications. Since June 2017, helium suppliers have had draw limits on the amount of helium one could purchase because of a supply shortage. Due to social distancing measures resulting from the COVID-19 pandemic, many birthday parties have been canceled and the demand for party balloons has dropped immensely. Prior to the pandemic, balloons were responsible for at least 10% of the helium usage. The decrease in demand seems to have ended the helium shortage for now. However, some scientists have noticed price hikes when ordering helium for their experiments. So while there may not be need to worry about supply in the near future, prices may be a source of concern if the trend continues.

3. “World’s Physics Instruments Turn Their Focus to COVID-19,” by David Kramer, May 1, 2020

Science facilities around the world have reopened their doors post shutdown and focused their instruments on research into the COVID-19 virus. For example, the Advanced Photon Source at Argonne National Laboratory can use multiple beamlines to study the proteins encoded by the virus. At the UK’s Diamond Light Source, researchers are working from home to analyze how potential drug components interact with the virus through a process called fragment screening. Some groups, including a team at the University of Texas at Austin, are using cryoelectron microscopy to examine the structure of proteins that resist crystallization. The path to a drug-based treatment or vaccine that can slow or even stop the current pandemic is long, but as Kramer demonstrates in this article, physics instruments are likely to play an important role in the process.

4. “Commentary: Disentangling Anti-Blackness from Physics,” by Charles D. Brown II, July 20, 2020

Charles D. Brown II, postdoctoral researcher in the Ultracold Atomic Physics Group at the University of California, Berkeley, shares a frightening experience he had with police that occurred in Chicago during one of his nightly runs as an undergraduate. He was aggressively approached and physically assaulted. He ties this experience into his life in academia, stating, “Black scholars experience widespread bias and discrimination and are subjected to both interpersonal and systemic anti-Black racism.” In 2017, Black students were awarded only 3% of physics bachelor’s degrees. In this article, Brown shares numerous examples of how racism pushed him away from physics and academia, and he notes that these experiences aren’t unique—Black students still face these challenges in academia. The article includes a call to action and concrete steps that faculty, students, and departments can take to help create a more successful and inclusive community, such as educating yourself and listening to Black students and scientists, and acknowledging your biases and working to correct them.

5. “An Atomic Physics Perspective on the Kilogram’s New Definition,” by Wolfgang Ketterle and Alan Jamison, May 1, 2020

The kilogram, previously defined by a physical weight in Paris, has recently been redefined in terms of Planck’s constant, or more plainly, atomic frequency. Similarly, other standard units of measure have been redefined in terms of constants of nature, such as the meter, which is now defined in terms of the speed of light. In this article, Ketterle and Jamison explore the new definition and what it means physically to have the kilogram defined in terms of Planck’s constant. The main benefit of this redefinition is that unlike physical artifacts, it is not subject to decay over time.

6. “Hubble’s 30-Year Legacy,” by Nadieh Bremer and Andrew Grant, April 1, 2020

In April 1990, Physics Today ran an article about the Hubble Space Telescope set to launch later that month. Thirty years later, Hubble has dramatically changed how we view the universe. By looking more closely and deeply at the universe than humanity ever has before, the telescope has revolutionized our understanding of the cosmos and our place within it. Included in the article is a four-page visual highlighting some of Hubble’s accomplishments over the past three decades, such as the Ultra Deep Field image and imaging of nebulas and galaxies. The Hubble Telescope is still making new discoveries and is predicted to keep observing the universe until at least 2025. Galaxy NGC 2442 imaged by the Hubble Space Telescope. Photo courtesy of  ESA/Hubble & NASA, S. Smartt et al.

7. “Academics to Stage Strike for Black Lives, ShutDownSTEM on 10 June,” by Andrew Grant, June 8, 2020

On Wednesday, June 10, 2020, many physicists and other STEM communities shut down all of their normal academic activities to instead educate themselves and reflect on how they can take action to aid in the fight for justice. The idea was conceived by Chanda Prescod-Weinstein, a particle cosmology theorist and feminist theorist at the University of New Hampshire, and Brian Nord, cosmologist and Fermilab physicist, and coordinated in conjunction with #ShutDownSTEM and a diverse group of physicists known as Particles for Justice. The idea for the strike came about amidst the protests against systemic racism and police violence during the spring of 2020. Non-Black academics were encouraged to use the day “to educate themselves and advocate for change in their communities.” The day also encouraged academics to rethink the way they perform their normal duties and challenged them to combat anti-Blackness in the world at large.

8. “Gravitational-Lensing Measurements Push Hubble-Constant Discrepancy Past 5σ,” by Johanna L. Miller, March 1, 2020

The Hubble constant (H0) tells us how fast the universe is expanding. Two prominent methods of measuring H0 are the ΛCDM model and the distance–velocity method utilizing cosmic events such as supernovae. The ΛCDM model measures H0 to be 67.4 ± 0.5 km/s/Mpc and the distance–velocity method measures it to be 74.0 ± 1.4 km/s/Mpc. The difference between these two magnitudes could be explained by systemic uncertainty in methodology. A new measurement by the H0LiCOW collaboration using gravitationally lensed quasars, however, measures H0 to be 73.3 + 1.7 − 1.8 km/s/Mpc. The article explains the discrepancy in these measurements and how it affects our view of the universe.

9. “COVID-19 Pandemic Modeling Is Fraught with Uncertainties,” by David Kramer, June 1, 2020

Modeling of the COVID-19 pandemic spread over time in Georgia showed that even if lockdowns had been extended through mid-May instead of lifting May 1, infections would have climbed extremely quickly. This article notes that different models from groups around the country predicted a peak in cases that has already been surpassed. Kramer uses what happened in Georgia to demonstrate that the uncertainties surrounding the virus lead to large error bars in predictions, and there are many models to choose from that change and evolve every day. Alison Hill, a research fellow at Harvard University, says one factor to look for in a model is the education and skill level of the people involved. While these models can change and disagree with one another, as they are continuously fine-tuned they can be used to interpret and benefit decision-making for the future.

10. “Does New Physics Lurk inside Living Matter?,” by Paul Davies, August 1, 2020

Without being able to explain life, it is very hard to look for it in other places. Paul Davies writes, “Asked whether physics can explain life, most physicists would answer yes. The more pertinent question, however, is whether known physics is up to the job or whether something fundamentally new is required.” Davies dives deep into examining how different fields of physics may be able to explain life but argues that there may be a new field of physics waiting to be discovered that’s necessary to explain what life is.

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