Here at Physics Buzz, we’ve previously explored how artificial intelligence has helped us fight pandemics. But I also wanted to know: how has physics research aided in the fight to combat this pandemic? How does physics research overlap with other sciences — including epidemiology, medicine, virology, among others — to uncover new knowledge about COVID-19? What is the role of physics in our pandemic response?
A quick search on the arXiv shows that more than 700 preprints mentioning “COVID-19” in the title have been uploaded within the past four months. As it turns out, there are many different ways physics is helping us navigate this uncertainty. Here are just a few in detail:
Physics and Structural Biology: Mapping Proteins
Physics-based techniques have played an influential role in structural biology — the study of the structure and function of biological macromolecules. The vast majority of macromolecular structures are identified through x-ray crystallography — a process in which data is collected by diffracting x-rays from a single crystal. Based on the diffraction pattern from the scattered x-rays, structural biologists can reconstruct the macromolecular structure in question.
Synchrotron radiation sources — large facilities that accelerate beams of electrons to relativistic speeds in a continuous ring — are ideal spaces for larger-scale macromolecular crystallography. The first 3D structure of the main COVID-19 protease protein was mapped from data obtained using x-ray crystallography at the Shanghai Synchrotron Radiation Facility. Other facilities — including the National Synchrotron Light Source II at Brookhaven National Laboratory, SLAC’s Stanford Synchrotron Radiation Lightsouce, and the Advanced Light Source at Lawrence Berkeley National Lab — are currently operating beam lines focused only on coronavirus research.
An additional method useful for determining protein structures is cryoelectron microscopy. This technique — whose developers were awarded the 2017 Nobel Prize in Chemistry — allows scientists to examine the structure of molecules and materials at the atomic scale using electron beams. A team at the University of Texas at Austin utilized this technique to identify the structure of the spike protein in the COVID-19 virus, which is considered a key target for vaccines and therapeutic antibodies.
Virus Transmission and Fluid Dynamics
Fluid dynamics is a branch of physics that is concerned with how liquids and gases flow. Given that viruses travel through infectious droplets through the air, fluid dynamics offers a natural approach to a better understanding of how infections can spread from person to person. Previous research in this area has deepened our understanding of how influenza is transmitted through airborne disease particles from “super-spreaders” or “super-emitters.” However, there is not yet a consensus on how different viruses (including COVID-19) transmit through the air.
The growth of COVID-19 cases is superimposed on a simulation showing vortices generated by a cough through a facemask.
Image Credit: Mittal, R., Ni, R., & Seo, J. (2020). The flow physics of COVID-19. Journal of Fluid Mechanics, 894, F2. doi:10.1017/jfm.2020.330
Dr. Rajat Mittal, a professor of mechanical engineering and expert in computational fluid dynamics, has been thinking about how fluid dynamics can aid COVID-19 research. “As I started to dive into the literature, it became clear that fluid dynamics intersects with nearly every aspect of this pandemic. How droplets are formed and carried, how they infect others, the ventilators we use to treat patients with this disease, even preventive measures like face masks—many of these problems are ultimately related to fluid flow,” he told phys.org. He and other experts recently published a paper in the Journal of Fluid Mechanics summarizing what we already know — and will need to know — in order to better understand the spread of COVID-19 and more effectively protect ourselves.
Ventilators, Big Data, and High-Energy Physics
CERN announced in early April that it was organizing a task force to “identify and support contributions from the organization’s 18,000-strong global [particle physics] community” in order to help combat the pandemic. “We want to deploy our resources and competences to contribute to the fight,” said CERN Director-General Fabiola Gianotti in a press release. One project that has resulted from CERN’s COVID-19 efforts is a new ventilator, called the HEV (High-Energy physics community Ventilator). The ventilator is relatively cheap and can run on batteries, solar power, or a backup generator. It is currently in the prototyping stage.
|Image Credit: CERN.|
High-energy physicists are also contributing their big data expertise to aid coronavirus research. Science Responds was organized to “facilitate interaction between COVID-19 researchers and the broader scientific community,” serving as a platform through which physicists can identify and contribute to projects focused on finding treatments and cures or supporting hospitals and healthcare systems. “The physics community has extensive experience storing, distributing, and analyzing large complex datasets and coordinating activities across universities, labs, and countries. We as physicists are thus well positioned to contribute to efforts to mitigate the effects of this pandemic,” noted Dr. Savannah Thais, Science Responds co-founder and a post-doctoral researcher in high-energy physics at Princeton University, in her presentation at the virtual APS meeting in April.
Mathematical Models to Forecast Pandemic Spread
Mathematical modeling has also been central to measuring and tracking the spread of COVID-19. “Mathematical and computational models are ideal as forecasting tools and can also provide situational awareness when we lack good data or define counterfactual scenarios that help disentangle the impact of pharmaceutical interventions and public health policies,” write the authors of a recent paper published in Nature Reviews Physics.
Chaos theory analysis has been a useful mathematical approach to mapping the virus’s spread. Researchers in Brazil analyzed the growth of confirmed infected cases across four continents and published their results in Chaos: An Interdisciplinary Journal of Nonlinear Science. The group used a numerical modeling technique that utilizes computing power to simultaneously solve a collection of differential equations. The resulting high-correlation in power-law curves between each country allowed the researchers to isolate and identify which quarantine containment strategies have been more effective than others.
You may have heard politicians describe their decisions about quarantine restrictions as “data-driven,” meaning that they’re likely consulting statistical models to guide their strategy.
Physics Today recently reported that policymakers are being presented with a “plethora of predictions” about how the virus could continue to spread. “[A statistical model] fits the data well. It describes what really happened, and that maybe it’s reasonable to expect that the trend will keep going in a particular direction,” said Alison Hill, a Harvard University research fellow. However, “there’s no natural law that says epidemics have to follow that curve.” Because individual models have limitations, it’s important to consult more than one in order to assemble a broader picture of the current situation. In fact, the CDC shares more than twenty different models on its website forecasting potential futures of the pandemic.
Physicists in the COVID-19 Fight
The COVID-19 pandemic shows the necessity of a “big science” approach to combatting this virus. Identifying effective solutions to this pandemic is a global, interdisciplinary, and multi-faceted challenge, one that demands scientists with wide-ranging expertise collaborate in order to be solved. Whether through contributions to structural biology, fluid dynamics, big data, or mathematical models, physicists are active in the COVID-19 fight in numerous impactful ways.
By Hannah Pell
“What’s going on in this video? Our science teacher claims that the pain comes from a small electrical shock, but we believe that this is due to the absorption of light. Please help us resolve this dispute!”
(We’ve since updated this article to include the science behind vegan ice cream. To learn more about ice cream science, check out The Science of Ice Cream, Redux)
Over at [email protected] there’s an easy recipe for homemade ice cream. But what kind of milk should you use to make ice cream? And do you really need to chill the ice cream base before making it? Why do ice cream recipes always call for salt on ice?