Volume 109. Number 3. May–June 2021 American Scientist

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A model of forces that MOVE THE EARTH

Spawned from "junk" DNA: HOW GENES ARE BORN

AMERICAN

Scientist May–June M J 2021

www.americanscientist.org i i ti t

Cosmic Particle New theories could finally unmask the dark matter that shapes the universe.

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AMERICAN

Scientist Departments

Volume 109 • Number 3 • May–June 2021

Feature Articles

130 From the Editors 131 Letters to the Editors 134 Spotlight Isolating the instructions for life • DART (Double Asteroid Redirection Test) • Learning from pandemic perinatal experiences • Briefings 144 Perspective An octet in Flushing Meadows Roald Hoffmann and Dasari L. V. K. Prasad 148 Engineering Elevators rise to the occasion Henry Petroski 152 Arts Lab Tinkering with crystals

Scientists’ Nightstand 182 Book Reviews Physicians of the Manhattan Project • The drawbacks of making threats

158 158 Enter the Axion A new fundamental particle could solve a major puzzle in particle physics—and also explain the nature of the dark matter that permeates the universe. Chanda Prescod-Weinstein 166 The Chicken, the Egg, and Plate Tectonics Whole-planet models could upend our view of how geophysical forces shape the Earth. Nicolas Coltice

166 174 Turning Junk into Us: How Genes Are Born You are garbage. Don’t feel too bad, though—so is everyone else. Now, geneticists are learning what all the junk in your genome has been doing all along. Emily Mortola and Manyuan Long

From Sigma Xi 187 Sigma Xi Today Sigma Xi launches online student networking program • Registration open for Annual Meeting and Student Research Conference • Breaking barriers: women in STEM

174 The Cov er Enormous collections of invisible dark matter are thought to have seeded the formation of galaxies in the early universe. This computer simulation, created by a team led by Hsi-Yu Schive of National Taiwan University in Taipei, maps dark matter based on its density to make its structure obvious. Despite substantial evidence for dark matter, nobody has yet detected it directly. In “Enter the Axion” (pages 158–165), physicist Chanda Prescod-Weinstein explores the increasingly popular idea that dark matter consists of particles called axions. Over large scales, axions could act like waves rather than collections of particles, producing the rippled forms seen on the cover. Prescod-Weinstein is studying the cosmological implications of this phenomenon and assisting efforts to determine whether axions really exist. (Cover image courtesy of H.-Y. Schive et al., with permission from Nature Physics. https://doi.org/10.1038/nphys2996)

From the Editors AMERICAN

Scientist

Hidden Secrets at All Scales

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Z

Nicolas Coltice, Maëlis Arnould et al.

oom out to the level of the whole universe, if you can imagine that. Looking at the whole thing at once, you might notice that there’s a lot that you actually cannot see. We can observe this same quandary at smaller scales: Stars in galactic systems rotate as if much more mass is present than the stars could contain. So where is this mass? This mysterious stuff is what astrophysicists call dark matter, but as University of New Hampshire theoretical physicist Chanda Prescod-Weinstein points out in our cover feature (“Enter the Axion,” pages 158–165), that moniker is really a misnomer. As she says, we can see light bouncing off dark objects, but so-called dark matter doesn’t interact with electromagnetic radiation at all. It’s more hidden to us than if it were simply dark. So how do we go about getting data about something that we can’t image with any known methods? What could dark matter be made of? There are a number of theories, but in her article, Prescod-Weinstein discusses a promising theoretical particle called the axion, and a number of experiments that are aimed at finding evidence of its existence. There are hidden phenomena in nature at all scales. Let’s zoom in now from the whole universe to our own planet. We can see the surface of it, but the interior is more mysterious. What’s happening in its roiling depths, and does that activity shape the surface—or does the surface shape the interior? In “The Chicken, the Egg, and Plate Tectonics” (pages 166–173), geodynamicist Nicolas Coltice of École Normale Supérieure in Paris describes a decade of effort to create models of the Earth’s interior that are as accurate as climate models (one example showing the surface and interior convection is at right). His research shows how the dynamic activity of Earth’s interior can alter the ways that rocks themselves behave and move on the surface of our planet, hundreds or thousands of kilometers away. Zoom in again, this time to the scale of our genetic material inside our cells. There’s a lot going on in our DNA as it forms RNA, which then forms proteins that our bodies need to function. But there’s quite of a lot of DNA that doesn’t seem to do much at first glance, which has been labeled junk DNA. Why would such long stretches of seemingly useless code stick around? It may not be surprising to find out that it’s there because it’s not so useless after all. In “Turning Junk into Us: How Genes Are Born” (pages 174–181), Emily Mortola and Manyuan Long of the University of Chicago describe their extensive research aimed at seeing beyond the assumptions and figuring out the process through which these stretches of nonsense DNA start evolving and eventually begin producing functional proteins. Throughout this issue, there are other stories of exploration leading to unexpected discoveries, from the first isolation of nucleic acids, to artistic depictions of electrons, to serendipitous patterns of crystal growth on organic objects, to a new mission to move an asteroid. We hope all these accounts inspire you to search for new ways of seeing—or sensing by other means—the workings of everything around us. —Fenella Saunders (@FenellaSaunders)

VOLUME 109, NUMBER 3 Editor-in-Chief Fenella Saunders Managing Editor Stacey Lutkoski Senior Consulting Editor Corey S. Powell Digital Features Editor Katie L. Burke Senior Contributing Editor Sarah Webb Contributing Editors Sandra J. Ackerman, Emily Buehler, Christa Evans, Jeremy Hawkins, Efraín E. Rivera-Serrano, Diana Robinson Editorial Associate Mia Evans Intern Reporter Lily Pinchbeck Art Director Barbara J. Aulicino SCIENTISTS’ NIGHTSTAND Book Review Editor Flora Taylor AMERICAN SCIENTIST ONLINE Digital Managing Editor Robert Frederick Acting Digital Media Specialist Kindra Thomas Acting Social Media Specialist Efraín E. Rivera-Serrano Publisher Jamie L. Vernon CIRCULATION AND MARKETING NPS Media Group • Beth Ulman, account director ADVERTISING SALES [email protected] • 800-282-0444 EDITORIAL AND SUBSCRIPTION CORRESPONDENCE American Scientist P.O. Box 13975 Research Triangle Park, NC 27709 919-549-0097 • 919-549-0090 fax [email protected] • [email protected] PUBLISHED BY SIGMA XI, THE SCIENTIFIC RESEARCH HONOR SOCIETY President Sonya T. Smith Treasurer David Baker President-Elect Robert T. Pennock Immediate Past President Geraldine L. Richmond Executive Director Jamie L. Vernon American Scientist gratefully acknowledges support for “Engineering” through the Leroy Record Fund. Sigma Xi, The Scientific Research Honor Society is a society of scientists and engineers, founded in 1886 to recognize scientific achievement. A diverse organization of members and chapters, the Society fosters interaction among science, technology, and society; encourages appreciation and support of original work in science and technology; and promotes ethics and excellence in scientific and engineering research. Printed in USA

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Letters Creating Green Hydrogen To the Editors: The concept of using “green” hydrogen in a fuel-fired power plant, as discussed in Lee S. Langston’s article “Generating a Cleaner Future” (Technologue, March–April), leaves me with a basic question: If green hydrogen is created by the electrolysis of water, will it not require more electrical power from the grid to make the hydrogen than can be returned to the grid by burning the hydrogen as fuel? Using the most efficient processing available today, the electrolysis of water would take more than twice as much power as the resulting burning of hydrogen would provide. And no matter what improvements can be made to the efficiencies of the electrolysis and combustion processes, it will always take more power to produce the hydrogen than can be generated from burning it. Unless there is a means to create hydrogen other than the electrolysis of water, what is the reasoning that leads one to pursue the use of hydrogen as a fuel in a gas-fired power plant? W. M. Goldberger Columbus, OH

Dr. Langston responds: You are certainly correct that the process of electrolyzing water to produce hydrogen will require electrical power—from somewhere. The key words in my explanation are “created from a surplus of renewable energy.” One problem with wind- and solar-generated electricity is what to do with those electrons when there is no market for them. For instance, Denmark has on occasion resorted to paying neighboring countries to take surpluses of its extensive wind power electricity rather than shut down whole arrays of its wind turbines. Germany has had a similar problem with surplus solar power generated in its southern states. Using that extra energy to create hydrogen would be a way to perpetuate green power.

Venusian Atmosphere To the Editors: I read Paul Byrne’s article “Unveiling Earth’s Wayward Twin” (January– February) with great interest. I learned a lot I had not known about the planet we once believed to be our near-twin and gained a better understanding of how studying Venus could help us learn more about planets outside our own Solar System.

Two facts that struck me are that Venus’s atmosphere is so much denser than Earth’s and that Venus has far fewer impact craters relative to other planets and moons. The author suggests that these facts show that Venus’s surface must have formed much more recently than that of, say, Mars. That’s certainly a possibility. But might not Venus’s very dense atmosphere affect both the number and size distribution of impact craters? A dense atmosphere will burn up more incoming objects than a thin atmosphere, such as that of Mars, will. Small objects entering Venus’s thick atmosphere will be most likely to burn up completely, but even the surface effects of larger objects will be reduced. Perhaps Venus’s surface is old but little battered. In any case, the author made a convincing case that Venus certainly deserves more study than it’s received so far given how different it is from Earth despite a few great similarities. John Cushing Bend, OR Dr. Byrne responds: It’s true that Venus’s atmosphere does a very effective job screening incoming asteroids and comets from hitting

American Scientist (ISSN 0003-0996) is published bimonthly by Sigma Xi, The Scientific Research Honor Society, P.O. Box 13975, Research Triangle Park, NC 27709 (919-549-0097). Newsstand single copy $5.95. Back issues $7.95 per copy for 1st class mailing. U.S. subscriptions: one year print or digital $30, print and digital $36. Canadian subscriptions: add $8 for shipping; other foreign subscriptions: add $16 for shipping. U.S. institutional rate: $75; Canadian $83; other foreign $91. Copyright © 2021 by Sigma Xi, The Scientific Research Honor Society, Inc. All rights reserved. No part of this publication may be reproduced by any mechanical, photographic, or electronic process, nor may it be stored in a retrieval system, transmitted, or otherwise copied, except for onetime noncommercial, personal use, without written permission of the publisher. Second-class postage paid at Durham, NC, and additional mailing offices. Postmaster: Send change of address form 3579 to Sigma Xi, P.O. Box 13975, Research Triangle Park, NC 27709. Canadian publications mail agreement no. 40040263. Return undeliverable Canadian addresses to P. O. Box 503, RPO West Beaver Creek, Richmond Hill, Ontario L4B 4R6.

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Virtually Lost Knowledge

Francisco J. AragÓn Artacho/Jonathan M. Morwein/CARMA

Tracking the Pandemic

Integrating big data into surveillance models can provide near-real-time information about the spread of COVID-19. Shweta Bansal, associate professor of biology at Georgetown University, discussed how these models can inform decision-making about pandemic policies as part of the Sigma Xi Virtual COVID-19 Distinguished Lectureship Series. https://bit.ly/3f5QWrM

Seeing the Unseeable

A new documentary film provides a fly-on-the-wall view of two recent endeavors to understand black holes: the work of the Event Horizon Telescope team to make the first picture of a black hole and a theoretical initiative to resolve the black hole information paradox. https://bit.ly/3cOGYZ2 Check out AmSci Blogs http://www.amsci.org/blog/

A Special Collection for Pi Day

To celebrate March 14 (frequently abbreviated as 3-14), the editors dug into the American Scientist archives and compiled a compendium of articles all about π. The digital collection is available as a premium to subscribers. https://bit.ly/2OYR3L7 Does In-Person Schooling Contribute to COVID-19 Spread?

Two new well-designed studies indicate that in-person schooling does not contribute to SARSCoV-2 transmission when baseline community spread is low, but it does when spread is high. https://bit.ly/3cP5yJb the surface. In fact, there are relatively few craters less than 25 kilometers in diameter, and none less than 3 kilometers, purely because of that thick atmosphere’s ability to shield the surface from impactors. However, Venus doesn’t boast any of the really large impact basins that are so common on Mercury, the Moon, or Mars, say— none of the 500- kilo meter-wide, 1,000-kilometer-wide, or even bigger 132

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basins such as Caloris on Mercury, Orientale on the Moon, and Hellas on Mars. Indeed, the largest impact feature on Venus is Mead crater, which is about 280 kilometers across; there are more than 40 basins larger than this on Mercury. Thus, although the atmosphere plays some role in the impact record (or lack thereof) on Venus, it’s far from the only factor responsible for the second planet’s relatively youthful average surface age.

To the Editors: Elizabeth Keating’s interesting article on the oddness of virtual meetings (“Why Do Virtual Meetings Feel So Weird?” Perspective, March–April) identifies problems that emerged three or four decades ago under different circumstances. In the 1980s, companies under pressure from corporate raiders and takeover operators began divesting operations that were deemed “noncore.” This move marked the beginning of a trend away from vertical integration (where a company does everything it needs to design and make its products in-house) to outsourcing (a company contracts with other businesses to perform many of these tasks). Not only did this change break social and cultural bonds, but it also broke technical links—interactions between the product’s components that had to be kept in mind to create a competent design. My colleagues and I at the MIT Leaders for Global Operations have published research on this topic. Outsourcing transforms personal and corporate relationships from collegial to transactional, and the loss of internal knowledge was severe. In many situations, a personal visit allowed for three-dimensional visualization of both things and people. These interactions are indispensable, especially for those who do not pick up on body language and other forms of nonverbal communication. (I speak from personal experience.) Though the topics Keating raises are not new, the internet has brought them to the surface again. There are, as far as I can tell, no good technological solutions. Daniel Whitney Redmond, WA

How to Write to American Scientist

Brief letters commenting on articles appearing in the magazine are welcomed. The editors reserve the right to edit submissions. Please include an email address if possible. Address: Letters to the Editors, P.O. Box 13975, Research Triangle Park, NC 27709 or [email protected].

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Spotlight | Sesquicentennial of the discovery of nucleic acids

Isolating the Instructions for Life Friedrich Miescher was a pioneer in the field of molecular genetics, but he never achieved scientific rock-star status. In the winter of 1869, Friedrich Miescher (1844–1895), a young Swiss doctor, was working in the former kitchen of a medieval castle in Tübingen, Germany. His aim: to uncover the chemical basis of life. He used pus-soaked bandages from a local hospital to first isolate cells, then their nuclei. From the latter, he extracted an enigmatic substance. When analyzing it, he found that it had chemical properties unlike any molecule described before. (See “The First Discovery of DNA,” July–August 2008, for more about Miescher’s methods.) Miescher found that nucleic acids were present in the nuclei of every cell type he studied. He also noticed that the amount of DNA increased in proliferating tissues,

Courtesy of the University of Tübingen and Ralf Dahm

Conversations in the first half of 2021 are dominated by COVID-19 vaccines: where they are being distributed, who has had the coveted shots, and how life will change after the majority of adults have been vaccinated. The journal Science even chose RNA-based vaccines as their “2020 Breakthrough of the Year.” These developments are, of course, highly welcome, and they could not have been achieved without a key event that occurred 150 years ago but that is now virtually forgotten: the discovery of nucleic acids, DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). This finding marked the start of a new era in our understanding of organisms and disease. But the story also holds lessons in how we remember those who bring about breakthroughs.

This year is the 150th anniversary of Friedrich Miescher’s discovery of nucleic acids, a finding that marks the beginning of modern molecular genetic research. The Swiss doctor conducted his experiments in the former kitchen of Hohentübingen, a medieval castle that is now part of the University of Tübingen. 134

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including tumors, and he briefly speculated that DNA might play a role in fertilization and the transmission of heritable traits. When he published his discovery in 1871, Miescher was so convinced of the significance of the new substance that he considered it “tantamount in importance to proteins.” These insights were prescient at the time; it is hard to make a bigger discovery than DNA. Indeed, DNA is so central to how we think about biology today that it has become the icon of the life sciences and is deeply embedded in our culture. Yet, very few know of Miescher and his discovery. By contrast, James Watson and Francis Crick—the scientists who revealed the structure of DNA—have achieved almost rock star–like fame. There are several reasons for Miescher’s relative obscurity. In some ways, his discoveries were just too far ahead of their time. For decades, DNA, which is composed of only four building blocks, was considered too simple a molecule to encode the complexity of life in all its forms. Instead, the proteins, comprising 20 amino acids, were favored as carriers of hereditary information. Only in 1944—75 years after Miescher’s discovery—did scientists show that DNA is the genetic material. At that point, the race was on to understand how DNA encodes information. But it took another nine years before Watson and Crick uncovered the structure of DNA: the now iconic double helix. Coincidentally, 2021 marks another anniversary in the history of DNA research: The first drafts of the complete human genome sequence were published 20 years ago by the International Human Genome Sequencing Consortium and the firm Celera Genomics. This event was another landmark for the life sciences and biomedicine. It also ushered in the era of big data in biology. Huge datasets produced by various genomics projects around the world have transformed our understanding of how we develop, age, and become ill. (See “Turning Junk into Us,” pages 174–181, for one application.) They also further our comprehension of how life evolved and

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how ecosystems function. Thanks to genomics, scientists have made major steps toward Miescher’s dream of understanding the chemical basis of life. In recent years, molecular genetics has led to the development of new, personalized treatments for a variety of diseases. Innovations such as CRISPR-based genome editing have opened the door to a new era of genuine precision medicine. Moreover, RNA-based vaccines, such as those currently employed to fight COVID-19, may prove equally effective at combating cancer and other major diseases. A century and a half after Miescher first announced DNA and RNA to the world, scientists are not only making great strides toward understanding the operating instructions of living beings, they are also increasingly able to treat diseases in ways unimaginable only a few years ago. Given that these groundbreaking developments are based on Miescher’s seminal discoveries, it is all the more surprising that he is so little known today. Aside from being too far ahead of his time, another reason for Miescher passing comparatively unnoticed may be his disinclination toward engaging in communication and self-promotion. Un-

A single strand of DNA, as shown in this color-enhanced transmission electron micrograph, contains the genetic material required for life. Miescher was convinced that he had found a fundamental component of living organisms, but it took another 75 years before the scientific community recognized the significance of his discovery.

like Watson and Crick, who were gifted communicators, Miescher was introverted, gave few talks, and did not interact much with colleagues. He published little and when he did, he wrote long and convoluted papers with key messages often buried deep in less important details. Thus, we can learn a lesson from

Miescher’s story: Even the greatest discoveries require effective and accessible communication for them to be noticed and remembered. —Ralf Dahm Ralf Dahm is the director of scientific management at the Institute of Molecular Biology in Mainz, Germany. Email: [email protected]

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Infographic | Gary Schroeder

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First Person | Zaneta M. Thayer

Learning from Pandemic Perinatal Experiences Families who carefully planned the perfect time to welcome a new child into their lives were thrown into chaos in early 2020 by the spread of the COVID-19 pandemic. As healthcare systems reorganized their care around treating and preventing the disease, expectant parents faced uncertainty about how these changes would affect their pregnancy and birth plans. Biological anthropologist Zaneta M. Thayer of Dartmouth College studies how stress caused by this unpredictability affected pregnant individuals and their families. Thayer’s approach is biocultural, meaning that the biological factors affecting a person cannot be separated from the cultural elements of their surroundings. The COVID-19 pandemic created a stressful environment that could not ethically be replicated in normal circumstances, but it allowed Thayer to examine the far-reaching effects of stress on mothers and children both during and after gestation. She expects her study will continue for years to come as she looks for lingering effects on the participants. Thayer spoke with Scott Knowles, a historian of risk and disaster at the Korean Advanced Institute of Science and Technology, on his daily podcast, COVIDCalls. On the podcast, Knowles speaks to guests about the latest research and the far-reaching effects of the pandemic. This interview is part of an ongoing collaboration between American Scientist and COVIDCalls. It has been edited for length and clarity. What effects of the pandemic have you seen on maternal care?

People need a lot of emotional support through pregnancy, childbirth, and postpartum. What we’ve observed in the pandemic is a huge disruption to systems of support and a huge increase in uncertainty. As an example, people aren’t allowed to have support persons in prenatal appointments. They have to go to the ultrasound appointment by themselves. There were lots of stories last March and April about people having to give birth alone. Support persons who tested positive for COVID weren’t allowed to accompany them. Maybe they were planning on having a doula; now the doula can’t come to the birth because they’re allowed to have only one support person. There were even concerns and recommendations that if parents tested positive for COVID, their infant should be separated from them for two weeks, which is obviously severely traumatic. One thing that came up in our study was a lot of uncertainty among participants about how hospital protocols would be affected by COVID. And since there was no national response strategy, every hospital had its own regulations. What this meant was that, maybe you picked your hospital based on where you gave birth last time, or where a friend gave birth. Now, whether you chose hospital A versus www.americanscientist.org

hospital B could mean a drastically different birth experience. Hospital A might allow only one support person. Or at hospital B your partner might not be able to leave the hospital after you give birth because once they do, they can’t come back in. All sorts of different regulations were constantly changing, which was causing a lot of uncertainty and stress. And then after people come home with their babies, they normally have systems of support, such as friends and family bringing food and helping to watch the baby or other kids. But the parents didn’t have that either. So there’s been huge disruptions for people across this whole stage. After the baby is born, parents normally have a support system—siblings, parents, extended friend networks— that must have been disrupted as well.

Yes, we’ve been working on another analysis about the postpartum period, when these systems of support are particularly important. We’ve found that individuals who say that they’ve received less help with housework or with caring for their newborn in that postpartum period were likely to have more severe depression than those who were still able to get that support during the pandemic. We also looked at childcare disruptions, because if you have older kids, and now they’re not at school or in day care, you’re having

to care for them and a newborn and not getting help from anyone else. These childcare disruptions were also associated with more depression. What are some of the ways you think about how these stresses on pregnant mothers manifest themselves as effects on children?

One of the big things we think about when we’re talking about maternal stress and pregnancy is how it affects the developing baby. We know that maternal stress hormones, such as cortisol, can cross the placenta and influence fetal development. We think it can affect things such as birth weight and gestation length, so it potentially increases the risk of having a preterm baby. In the longer term, it can increase risk for metabolic or immune disease, and some psychiatric conditions in children as well. Now, obviously, the pandemic hasn’t quite been going on long enough to understand all of these long-term outcomes, but I am currently working on an analysis looking at fear of childbirth, which is something that happens independent of COVID, but which in our sample is very clearly exacerbated by COVID-related worries. As an example, there were individuals in our sample who were really concerned about catching COVID and the effects that it would have on their developing baby or who were afraid 2021

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that if they caught COVID their baby would be taken away from them at birth. All of these individuals had a higher “fear of childbirth” score. Basically, we give people a dial from zero to 100, and we say, “How calm or scared are you about your upcoming birth?” In the analysis I was running, I found associations between fear of childbirth and shorter gestation length as well as lower birth weight. In our study, we don’t have the same sample without the pandemic, and our sample is not nationally representative, so I can’t compare it to a nonpandemic time. But qualitatively, in terms of our participant responses, as well as looking at the association with COVID-specific variables, I think it’s an appropriate interpretation that fear of childbirth has been exacerbated during the pandemic, because of all the reasons we’ve been talking about. People are more afraid than ever of being separated from their babies, of not having support people in labor, and of having their pain management strategies and labor altered. What do you rely on to draw that causality between stress of a mother and the long-term health impact on a child?

In humans, we rely primarily on observational studies, such as this COVID study I’ve been describing, because it is unethical to experimentally expose people to stress during pregnancy. People are out in the world. Some of them are experiencing more stress during COVID than others. We’re interested in seeing how that natural variation and stress experience relates to outcomes in maternal and child health. But COVID does provide a quasinatural experiment, because it’s an unusual situation. Natural experiments can be particularly useful if you have a group of people before or after the incident or big natural disaster, or maybe two closely related populations, one of whom experiences it and the other doesn’t. I know there’s a whole proliferation of COVID-related studies, even many other studies looking at COVID and pregnancy. All of this observational research is supported by animal model research. We have a lot of experimental research in animals showing that prenatal stress leads to changes in offspring stress hormones, and changes in metabolism or immune function, that’s consistent with our observational studies 138

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in humans. And so that gives us more confidence that the associations we’re finding are meaningful. I’ve talked to people on COVIDCalls about radical changes they foresee in medical research, and also in the ways medicine is delivered. Is maternal care also wrapped up in that?

There’s been a predominant assumption within our society that hospitals are the place you give birth, and the pandemic caused a lot of people to rethink that for the first time on a much broader scale. There were people who thought, “I don’t want to go to the hospital—that’s where all the COVID patients are. What are my other options?” And when people explored those options, they realized that there

“The pandemic may be shifting some of the cultural norms about where we should be giving birth.” are not that many alternatives, because there are lots of structural factors that inhibit access to out-of-hospital community birth. Other places to give birth include freestanding birthing centers, but those are not available in all 50 states, and also home births, but they can also be difficult to access, they’re not covered by insurance, and they can only be attended by midwives. With the pandemic, you saw a lot of people trying to explore these community birth options for the first time. Individuals who went to those community birthing centers, oftentimes were very satisfied with it. My colleague Theresa E. Gildner and I have a paper in Frontiers in Sociology (February 18, 2021) that discusses how the pandemic is affecting our participants’ future maternity care preferences. We asked, “If you were to be-

come pregnant again, where would you give birth?” About 6 percent of our participants said that if they became pregnant again, they would give birth outside of a hospital; if you think back, only 3 percent of people give birth out of the hospital in the first place. Their responses suggest that the pandemic may be shifting some of the cultural norms about where we should be giving birth. Are there documented cases of children being taken away from mothers for a quarantine period after giving birth?

Yes, there are. We asked about it in our survey, and there were people who were separated from their infants at birth in our sample. One of the things I asked participants was whether the mothers felt like they had a choice or not. The official Centers for Disease Control and Prevention recommendations are for the provider to inform the patient that this was the recommended course of action, but that the patient has a right to decide about their medical care. So technically, the patient could refuse to be separated from their baby. We asked our participants whether they felt like it was presented to them as a choice or as something that they had to do. And all our participants said that they felt like it was something that they had to do and it was not presented to them as a choice. The U.S. guidelines were disconnected from the World Health Organization guidelines, which said that keeping moms and babies together is extremely important and should always be a priority. And there was no evidence to suggest vertical transmission from mom to baby of COVID. The mom should be masked and wash her hands, but she and the baby should be together. How did stress affect women who were pregnant but were also part of essential worker groups?

In our study, we asked people if they were working outside the home, and about whether the pandemic was affecting their work plans and how long they planned to work in pregnancy. We saw that work was a huge source of stress for people, because a lot of them felt like they had to choose between their health and their income. (continued on page 140)

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(continued from page 138) It caused a huge psychological burden for these people, because they didn’t feel like they had a choice, and they had to continue to expose themselves and their unborn baby. Are there COVID babies who will be studied as a population group for the rest of their lives?

Absolutely. With our own cohort, we have the potential to follow these children as they grow and develop, which is certainly an opportunity I had not anticipated a year ago. We’ve done two rounds of data collection so far: one during pregnancy and one about one month postnatal. We’re gearing up for a third data collection wave with questionnaires again, and we’re also going to collect hair from our participants—from the mothers and their babies—to look at cortisol stress hormone levels in hair. Based on research already out there, what effects might we be looking at for the life course of these children?

There’s certainly evidence for behavioral and psychological outcomes, such as anxiety or altered stress response. A lot of research suggests potential cardiovascular health effects. But I would say that when we look at those big cohort studies, there are modest associations that come out. One thing that is important to make clear is that sometimes when we do this research, we describe these prenatal stressors as like programming offspring health in a way that’s irreversible. And I think that can be damaging and pathologizing. Human bodies are sensitive to the environment beyond just the prenatal period. Even if we were able to find some modest associations at a population level, when we’re talking about individuals, I don’t want to imply that they’re doomed to disaster. What will be interesting to see is when and how, and in what way, life becomes normal again. And if there’s differences in the timing of that normalcy, how that can influence the longterm trajectories. Because again, the sensitive period of development isn’t only pregnancy. There’s this whole cohort of people who have had to go through some really difficult things in pregnancy and postpartum. What can we do 140

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AP Photo/Eric Gay

Because she was infected with COVID-19, new mom Clarissa Munoz was separated from her baby after giving birth at DHR Health in McAllen, Texas, in July 2020. The United States does not have a nationwide standard for pandemic maternity care, so regulations have varied among hospitals, including whether infected mothers are separated from their babies. The uncertainty of these standards has caused significant stress for many pregnant women.

to support them now and to try and make sure that we improve environments in order to avoid the development of these adverse outcomes? There are still things that we can do.

tively accurate assessment about that. It’s always a new adventure.

How has the pandemic changed the way that you work?

I had three undergrads who were about to go to the field last year, so we were working on their human subjects approvals. And when COVID hit, two of them decided that was it. They were overwhelmed and didn’t want to try to shift. But one of them shifted, and we did her study online. She was originally going to go to Peru and Japan, but we did all these remote surveys and interviews instead. And now I’m designing some other studies with undergrads, and we’re doing all online surveys. And so I find myself training students in an area where I never received training. I think there’s some value to internet surveys and to video interviews, in that we can reach more people quickly, and we can access people geographically who would otherwise be difficult to reach. But I still think there’s something about face to face that will never die. So I do think that maybe this will become another tool in our toolkit that we can certainly improve the methods on and do better. And that’s a good thing to learn. But I’d like to think that it will not replace our traditional bread-and-butter data collection methods.

I’m an anthropologist, so normally I like to go places and talk to people and build rapport. And so in some ways, the online survey has been challenging because I haven’t gotten to see my participants face to face yet. We did provide a lot of opportunities for participants to provide openended responses, and in that sense, it’s been amazing to be able to hear these women’s voices, and read about their individual experiences that they have so graciously shared with us. But I am hoping in subsequent rounds that we will be able to do more interviews, even if it’s just over video for now. I’ve had to pivot and figure out how to use my skills differently. And certainly, even if I were to start a retrospective study anytime in the next few years where I generate a new cohort and talk to people, for better or worse, this pandemic has had a substantial enough effect that I think I can ask about specific things that have happened to people and have confidence that they’re being recalled with a high accuracy. For example, if I asked about whether someone’s financial situation was impacted by the pandemic, even five years down, hopefully, they can still give me a rela-

Do you think online study design is now going to become a requirement for anthropological training?

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A podcast interview with the researcher is available online.

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Briefings to speculation by some that the object could be alien technology. In a pair of papers in the Journal of Geophysical Research: Planets, astronomers Alan P. Jackson and Steven J. Desch of Arizona State University present some more plausible explanations for ‘Oumuamua’s oddities. They tested a variety of ices to see which would give the object the right albedo (the fraction of sunlight reflected back into space), and settled

I

n this roundup, managing editor Stacey Lutkoski summarizes notable recent developments in scientific research, selected from reports compiled in the free electronic newsletter Sigma Xi SmartBrief. www.smartbrief.com/sigmaxi/index.jsp

reconstructions of the letters, which a computational algorithm then unfolded. The researchers tested the technique on items from the Brienne Collection, a 17th-century Dutch postmaster’s trunk containing more than 3,000 undelivered letters. Reading these letters will help inform our understanding of the everyday lives of people in Renaissance Europe. Dambrogio, J., et al. Unlocking history through automated virtual unfolding of sealed documents imaged by X-ray microtomography. Nature Communications doi: 10.1038/s41467-021-21326-w (March 2).

Jarocka, E., J. A. Pruszynski, and R. S. Johansson. Human touch receptors are sensitive to spatial details on the scale of single fingerprint ridges. Journal of Neuroscience doi: 10.1523/ JNEUROSCI.1716-20.2021 (March 15).

CC-SA 4.0

Intricately folded Renaissance letters can now be read without damaging their delicate paper. A team of computer scientists, historians, conservationists, and dentists—yep, dentists—pooled their skills to develop an automated computational approach to uncovering the secrets in these messages. Before the invention of modern, self-sealing envelopes, correspondents kept their messages private with letterlocking, a complicated folding technique. The researchers used x-ray microtomography—a method used in dental research to examine cross-sections of teeth—to analyze the folded layers of paper; the technology also picks up ink on the paper. The team used these x-ray images to create 3D digital

Jackson, A. P., and S. J. Desch. 1I/‘Oumuamua as an N2 ice fragment of an exo-Pluto surface: I. Size and compositional constraints. Journal of Geophysical Research: Planets doi: 10.1029/2020JE006706 (March 16). Desch, S. J., and A. P. Jackson. 1I/’Oumuamua as an N2 ice fragment of an exo-Pluto surface II: Generation of N2 ice fragments and the origin of ‘Oumuamua. Journal of Geophysical Research: Planets doi: 10.1029/2020JE006807 (March 16).

Fingerprints Are Hypersensitive Interstellar Nitrogen Iceberg? The interstellar object ‘Oumuamua has puzzled astronomers since its discovery in 2017 because it was observed accelerating away from the Sun like a comet, but astronomers didn’t see any evidence of outgassing that would explain the increasing speed. This mystery even led 142

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Prehistoric Shark Had “Wings”

on nitrogen ice as the most likely candidate. ‘Oumuamua’s albedo is similar to that of Pluto and of Neptune’s moon Triton, both of which are covered in nitrogen ice. Furthermore, the evaporation of nitrogen ice would give the object a push, explaining its acceleration. Jackson and Desch suspect that ‘Oumuamua is a chunk that broke off of an exo-Pluto (a Pluto-like planet outside of our Solar System) and was propelled through space by a gravitational disruption in its home system. A similar event occurred in our Solar System billions of years ago, when Neptune’s migration caused collisions and the ejection of the majority of the Kuiper Belt’s mass.

The patterns on fingers are good for more than deducing whodunit. We have long known that fingers are sensitive, and a team of Swedish physiologists has discovered that much of that sensitivity is concentrated in the ridges of fingerprints. The researchers ran a series of raised dots over participants’ fingers

Paleontologists have discovered a Late Cretaceous shark fossil with features similar to those of a manta ray. The many species of modern sharks found in marine ecosystems worldwide share a common form: streamlined bodies with long tails used to propel themselves forward. This new fossil species, Aquilolamna milarcae, had sharks’ characteristic strong tail, but it also had a 190-centimeter pectoral fin span, making the animal wider than it was long. A. milarcae shares other features with manta rays, including a mouth that is

Wolfgang Stinnesbeck

Dambrogio, J., et al. CC BY-NC 4.0

Opening 17th-Century Mail

and tracked the reactions of individual nerve cells. They found that the areas with highest sensitivity are about 0.4 millimeters wide—approximately the same width as a fingerprint ridge. The topographies of these sensitive regions were consistent regardless of the speed or direction from which the raised dots passed over the participants’ fingers, and they followed the same unique pattern as their fingerprints. The high level of precision in our fingers for recognizing and spatially locating touch may help explain in part why humans are so dexterous.

better suited for filter feeding on plankton than for predation. The fossil may be an example of convergent evolution, and it indicates that despite the narrow range of body types in modern sharks, their evolutionary ancestors did experiment with a variety of forms. Vullo, R., E. Frey, C. Ifrim, M. A. González González, E. S. Stinnesbeck, and W. Stinnesbeck. Manta-like planktivorous sharks in Late Cretaceous oceans. Science doi: 10.1126/science.abc1490 (March 19).

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Perspective

An Octet in Flushing Meadows The Fountain of the Atom at the 1939 New York World’s Fair married art deco design with one of chemistry’s most enduring conceptual tools. Roald Hoffmann and Dasari L. V. K. Prasad

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n the spring of 1939, as the world emerged from the Great Depression and braced itself against the threat of impending war, the United States hosted an optimistic exhibition of a brighter future. The 1939 New York World’s Fair was a showcase of economic might, nationalism, culture, and modernist and art deco design. Visitors arriving in Flushing, Queens, by subway entered the fairgrounds through the Community Interests zone. To their right was the Hall of Fashion, to their left was the Town of Tomorrow, and straight ahead, the Home Furnishing building. In the center of this area stood the Fountain of the Atom. The Fountain of the Atom had distinct tiers resembling a wedding cake. On the upper terrace were four figures signifying each of the classical elements: earth, air, water, and fire. On the lower tier were eight ceramic sculptures, each representing an electron. Eight is not merely a lucky number, nor just the number of right practices on the Eightfold Path of Buddhism, it’s also the number of electrons associated with a stable atom. Life magazine, then at the height of its popularity, ran a 17-page photoessay on the World’s Fair just prior to its opening and gave a prominent place to the terra-cotta statues on the lower terrace in the fountain. They are electrons, but they are surely not your usual electrons. Nonetheless, the Life feature had no doubts of their significance, describing the electrons as “symbolizing the modern atomic theory of matter.”

A Precocious Sculptor The fountain’s statues are a high point of the ceramic art of American 144

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sculptor Waylande De Santis Gregory (1905–1971). Gregory collaborated on the fountain with architect Nembhard Culin (1908–1990), who designed the steel-framed structure, which also featured water running in columns and a flame burning from the top tier. It is unclear whether Gregory had any exposure to chemistry or physics in his education, but he certainly lived through the atomic age. He was

Chemistry has a wonderful way of adapting productive chemical concepts to alternative understandings of the underlying reality. a precocious, talented young sculptor who had mastered a variety of techniques but concentrated on the ceramic arts. Ceramics requires knowledge of practical chemistry, from the properties of different clay mixtures to the complex chemistry of glazes, as well as the engineering of precarious three-dimensional objects (the elements on the Fountain of the Atom’s upper tier were nearly 2 meters tall). Gregory mastered these many techniques, and he taught them in his years at the Cranbrook Academy of

Art, a modernist school in Bloomfield Hills, Michigan. There is no sign in Gregory’s previous work that he was familiar with the theory of atoms; however, he had shown a previous interest in scientific innovation. A year before the World’s Fair, Gregory created a fountain dedicated to Thomas Edison titled Light Dispelling Darkness, which you can still visit at Roosevelt Park in Edison, New Jersey. On one side of the fountain is a sculptural group titled Science and Achievement, which portrays people working with electrical equipment (including one holding a dynamo), as well as the medical sciences. But no chemists. So how did Gregory learn about the Lewis octet, the theory that eight electrons make for a strong and stable bonded atom? The Octet In an interview with the Illustrated London News published April 29, 1939—one day before the opening of the New York World’s Fair—Gregory says, “I based [the fountain’s] general design on the octet theory of the atom.” The vast majority of chemical compounds, including those that make up living organisms, testify to the special stability of the octet: eight electrons unshared or shared around carbon or other elements in the periodic table’s so-called main groups (columns 1–2 and 13–18). The fountain’s architectural design (the circular plan, several terraces, and the fixed number of figures on each terrace) is consistent with what a perceptive artist such as Gregory could have known at the time about the structure of the atom, and about the central role of electrons. The octet rule is attributed to Gilbert N. Lewis (1875–1946), one of the

Donald G. Larson Collection on International Expositions and Fairs, Special Collections Research Center, Henry Madden Library, California State University, Fresno

Visitors arriving at the 1939 New York World’s Fair were greeted by the Fountain of the Atom, an art deco celebration of chemistry. Ceramicist Waylande Gregory created 12 terra-cotta figures for the structure. The top tier featured representations of the four classical elements (earth, air, water, fire), and the lower tier displayed eight colorful, playful electrons. The octet of electrons represented a strong and stable bonded atom.

greatest American chemists, who laid the foundation for the electronic theory of chemical bonding. But the story of the octet is in fact a complex one, involving along the way independent discoveries by Richard Abegg, J. J. Thomson, Walther Kossel, and Irving Langmuir, and a dance between chemistry and physics in the first quarter of the 20th century. Gregory’s circular orbit representation in the Fountain of the Atom may have been inspired by Lewis’s theory, but it does not match with Lewis’s cubical model of the atom—not that the latter is right, anyway, except as a heuristic device. From the beginning, the “real” whereabouts of the electrons have been points of intense debate. American experimental physicist Robert Andrews Millikan wrote in 1924: The chemist has in general been content with what I will call the “loafer” electron theory. He has imagined these electrons sitting around on dry goods boxes at every corner ready to shake hands with, or hold on to, similar www.americanscientist.org

loafer electrons in other atoms. The physicist, on the other hand, has preferred to think of them as leading more active lives, playing ring-around-the-rosy, crackthe-whip, and other interesting games. In other words, he has pictured them as rotating with enormous speeds in orbits, and as occasionally flying out of these orbits for one reason or another [emphasis in the original]. Try as one might, thus far no one has “seen” an electron. The reason for the quotes is that seeing is a nontrivial disturbance of the system. At this scale, one has to give it a quantum mechanical operational significance, which in turn means considering Heisenberg’s uncertainty principle— that is, the moving electron does not exist at a perfectly defined location. Subject to those limitations, the electron cloud in an atom has been seen; it is certainly not cubical. More broadly, the detailed structure of the atoms that John Dalton (1766–

1844) postulated, the spectral lines that Robert Bunsen (1811–1899) discovered characteristic of the elements of the periodic table, and the nature of the radiant energy emitted from heated bodies all waited for their interpretations until the early 20th century, when Max Planck had his profound insight that the radiated energy will only be emitted in discrete quantities, called quanta. This quantum theory then set the stage for the work of Niels Bohr to propose the planetary model of electrons circulating around the nucleus of an atom, like tiny worlds orbiting a sun. This perspective on atoms could have been inspirational as well for Gregory as he contemplated the design of the Fountain of the Atom. In 1927, German physicists Walter Heitler and Fritz London developed a quantum mechanical treatment of the chemical bond. Lewis’s cube was replaced by electrons moving in indeterminate ways that we could only visualize on average, as an electron cloud attracted to the nuclei of the atoms involved in bonding. “Hybrid orbitals” pointing along the directions of the vertices of a tetrahedron came into play as a kind of housing assignment for the electrons. Linus Pauling’s great experience in structural chemistry, for which he won his first Nobel Prize in 1954, 2021

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The Evolution of Atomic Representations The concept of atoms—the minuscule building blocks of matter—has been around at least since the 5th century bce, when the Greek philosophers Leucippus and Democritus argued that there is a smallest possible component of matter. They called this fundamental unit atomos, meaning indivisible. The beginning of modern atomic theory is often credited to chemist John Dalton, who starting in 1803 proposed that each chemical element is composed of a single type of atom—an indestructible particle with a distinct mass and unique properties—which can combine with others to form compounds. Another century passed before physicist J. J. Thomson published his discovery of electrons, the first identified subatomic particles. Understanding the nature of the components of the atom was one challenge, but getting a comprehensible picture of how these components bind, and how atoms interact with other atoms, was another. Although the quantum model of electrons in orbitals moving around a nucleus is widely accepted as an accurate and useful representation, Gilbert N. Lewis’s dot structures appear to give a clearer description. Lewis structures focus on atoms’ valence electrons—the outer shell of electrons that can form chemical bonds. The main group of elements tends to form bonds that will create a stable shell of eight valence electrons, hence the octet of Gregory’s Fountain of the Atom. Lewis conceived of the valence shell as a box with electrons at each corner (as shown in this 1902 sketch by Lewis, top left). Over the years, these cubes have been flattened and simplified into the chemical notations familiar to anyone who has taken Chemistry 101 (bottom left).

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allowed him to reinterpret the Lewis octet in quantum mechanical terms, and reconcile the chemical and quantum mechanical views of the atom. Chemistry has a wonderful way of adapting productive chemical concepts to alternative understandings of the underlying reality. And so, despite knowing from quantum theory that the atom bears no resemblance to a hard, sculptural object, the octet remains the first of every chemist’s conceptual tools with which one tries to understand which molecules are likely to be stable, and which very reactive. Just right for the Fountain of the Atom, which married the streamlined aesthetic of Art Deco with scientific ideas that, in retrospect, marked the birth of the “Atomic Age.” Elemental Beauty Although, at first glance, the larger sculptures of the four elements may seem out of place on the Fountain of the Atom, Gregory viewed them as integral to the creation of ceramics. In a 1935 article in the journal Design, Gregory wrote: Earth, Water, Air, and Fire are all companions in the creation of a ceramic sculpture. Nature’s voice seems very near in the clay at one’s feet, awaiting the release, the command to speak. The earth seems pregnant with potential sculpture and when commanded by the creative force, the surge is unrelenting until complete crystallization

Electron sculpture photographs courtesy of University of Richmond Museums. From left: collection of Martin and Judy Stogniew; private collection; University of Richmond Museums, promised gift of Tom Folk; gift of the estate of Yolande Gregory

The Fountain of the Atom featured eight anthropomorphized electrons (above and at top of facing page). Gregory described the playful terra-cotta figures as participating in “a joyous, energetic dance around the nucleus.”

results in sculptured creatures of elemental beauty. That aptly expressed appreciation of “elemental beauty” may have led to Gregory’s interest in the atomic structures of elements. Around the lower tier of the fountain, four of the electrons are male and four are female. At least half of them have schematic lightning around them. One female electron is surrounded by bubbles, while a male electron sports fins. All are cavorting, in delight at their nudity, and seemingly able to defy gravity. The electrons are certainly fun. There are no hints of them stealing or sharing another electron, but then the architectural constraints of the fountain do not allow them to interact. In the real world, they would most certainly be up to something. Gregory described the electrons as boys and girls dancing a joyous, energetic dance around the nucleus. I portray them as elemental little savages of boundless electrical energy, dancing to the rhythm of sculptured bolts of lightninglike flashes in brilliant colored glazes, their buoyant bodies of richly modeled terra cotta clays in warm colors.

Courtesy of Alfred Ceramic Art Museum at Alfred University

Although the focus of the fountain was on the electrons and modernity, we cannot pass over the colonialist language. The headline of the Life article about the fountain paraphrased Gregory’s description: “These Little Savages Are Electrons.” Sadly, this was how the dominant powers in society at the time, without batting an eyelid, commonly depicted the “other”—as elemental primitives. These tropes were especially insidious at World’s Fairs, which were explicitly promotional, nationalistic spectacles.

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Honor to the Atom Gregory’s allegorical ceramic representation of the atom with the octet was noticed by Albert Einstein on April 30, 1939, when he visited the World’s Fair. He is quoted as saying to Gregory, “Young man, I wanted to To make ceramic sculptures, such as this representation of fire from the Fountain of the Atom, artists must harness all four of the classical elements. Gregory was a master at the medium and developed new techniques to create large-scale pieces.

meet the artist who gave honor to the atom.” Einstein was a great believer in visual and heuristic thinking, and we believe he is likely to have appreciated the sculptural solidity that Gregory crafted to “honor” the atom. It was also Einstein who gave us the quantum mechanics of light emission and absorption, and Lewis who invented the word “photon” (for what Einstein called light quanta, lichtquanten). The theory of how we see in absorption the radiant colors of the striking glazes that Gregory ground and mixed himself was formed by that other immigrant to New Jersey. When the World’s Fair was over, the Fountain of the Atom was disassembled, and its elements scattered. One can see individual pieces in the Cranbrook Academy collection, the Everson Museum of Art in Syracuse, New York, the University of Richmond Museums, and the Alfred Ceramic Art Museum at Alfred University. The dispersal of the Fountain of the Atom is itself a metaphor—the sculptural electrons moving off into the world, making new connections, bonding with new viewers. The electrons are still having fun. Bibliography Folk, T. C. 2013. Waylande Gregory: Art Deco Ceramics and the Atomic Impulse. Richmond, VA: University of Richmond Museums. Jensen, W. R. 1984. Abegg, Lewis, Langmuir, and the octet rule. Journal of Chemical Education 61:191–200. Karp, I., and S. D. Lavine, eds. 1991. Exhibiting Cultures: The Poetics and Politics of Museum Display. Washington, DC: Smithsonian Institution Press. Kohler, Jr., R. E. 1974. Irving Langmuir and the “octet” theory of valence. Historical Studies in the Physical Sciences 4:39–87. Lewis, G. N. 1916. The atom and the molecule. Journal of the American Chemical Society 38:762–785. Millikan, R. A. 1924. The physicist’s present conception of an atom. Science 59:473–476. Preziosi D., and C. Farago. 2004. Grasping the World: The Idea of the Museum. London: Routledge. Shaik, S. 2007. The Lewis Legacy: The chemical bond—a territory and heartland of chemistry. Journal of Computational Chemistry 28:51–61.

Roald Hoffmann is a theoretical chemist and the Frank H. T. Rhodes Professor of Humane Letters, Emeritus at Cornell University. He is also a writer, carving out his own land between poetry, philosophy, and science. Dasari L. V. K. Prasad is an assistant professor of chemistry at the Indian Institute of Technology Kanpur. He is currently dislodging electrons from crystal lattices. Email for Hoffmann: [email protected] 2021

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Engineering

Elevators Rise to the Occasion Virus safety now joins practicality and structural reliability as a performance metric for vertical transport. Henry Petroski

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alf a century ago, New York City’s Empire State Building was the tallest in the world, measuring 381 meters from the sidewalk to its roofline. It had set the height record upon its completion in 1931 and held onto it until the North Tower of the World Trade Center was topped out four decades later. In the meantime, architectural preference in skyscrapers had evolved from the Art Deco style of the Empire State Building to the Bauhaus-inspired International Style that emerged in the 1950s. Whereas the former was characterized by an ornamented and tiered profile that provided a form of buttressing, the latter was marked by strict rectilinear elements that were often unbroken from bottom to top. Without the structural advantages of buttresses, International Style buildings grew inherently more flexible as they rose to new heights. (Since 2010, the tallest building in the world has been the strongly buttressed 828-meter-tall Burj Khalifa in Dubai.) The pursuit of a world trade center in New York City began in earnest in 1943, when the state legislature passed a bill authorizing the development of plans for its realization. Exactly where it would be located became a point of disagreement between the states of New York and New Jersey, each of which had a seat at the table of the Port of New York Authority, the entity that controlled the metropolitan area’s airports, bridges, tunnels, and other significant infrastructure, including the planned trade center. (The entity has since been renamed the Henry Petroski is the Aleksandar S. Vesic Distinguished Professor Emeritus of Civil Engineering at Duke University. Address: Box 90287, Durham, NC 27708. 148

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Port Authority of New York and New Jersey, to reflect both states’ involvement.) New York pushed for a location on the Lower East Side of Manhattan, but New Jersey felt it should be on the West Side, which is across the Hudson River and New York Bay that separates the two states. The latter choice prevailed, in part because the megaproject could also help an area of the city that would benefit from urban renewal. A design competition for the project was won by Detroit-based architect Minoru Yamasaki, who was relatively unknown on the East Coast. His lack of reputation was no doubt a factor in the elite architectural community’s displeasure at the choice and, after the project’s completion, its almost universally negative reviews of the aesthetics of the Twin Towers. Yamasaki’s winning design called for each tower to be 80 stories high, but the Port Authority’s wish that the trade center have 930,000  square meters (10 million square feet) of office space drove the decision to build each tower 110 stories high, thus making them taller than any existing building. Obviously, this had great implications for the design of the engineered structure that would underlay the spare architectural facade. Structural engineers of the time realized that in high winds such a super-tall and super-slender building could experience unprecedentedly large horizontal motions, which occupants of the highest floors might find intolerable. The question was: How flexible could the towers be and, consequently, how much sway should be allowed? It was not a question answerable by theory; it had to be based on empirical data. An experiment to collect such data was devised in 1965 by the structural engineer Leslie E. Robertson. At the time, he was working for the

Seattle-based engineering firm of Worthington, Skilling, Helle, and Jackson, which had been selected to design the steel and concrete structure of the towers. It was Robertson’s first high-rise project, and he carried it out with distinction. In 1967, in recognition of his work, he was made a partner in the firm, which was renamed Skilling, Helle, Christiansen, Robertson. A decade after the completion of the Twin Towers project, the practice split its operations geographically, and the East Coast office was renamed Leslie E. Robertson Associates. A bit of subterfuge was used to collect data on human tolerance for sway. Advertisements were placed in a local newspaper on the West Coast offering free eye examinations at a new vision research center; people accepting the offer were directed to report to an ordinary-looking reception room in an unremarkable shopping center. After being checked in, the unwitting subjects were led into a windowless exam room that was, in fact, a motion simulator—a room-sized box mounted on a mechanism driven by hydraulic actuators. The subjects were instructed to stand at a mark on the floor and estimate the height of triangles projected on the wall. As they were doing so, unannounced to them the room began to move. The movement was increased until the subjects signaled that they noticed something funny. These experiments revealed that 10 percent of people could be expected to detect 5 to 10 centimeters of sway, and the average person about 12 centimeters. Keeping the sway of an actual building smaller than that would obviously bother fewer people. It may not have taken an experiment to come to that conclusion qualitatively, but Robertson had quanti-

fied what “small” actually meant. It was also important to keep a very tall building’s sway small enough that its elevator shafts did not bend and interfere with an elevator car’s movement within it. The final design of the Twin Towers ensured, by adjusting the buildings’ structural stiffness, that unacceptable amounts of movement were seldom reached. Even though the top of a tower as built could actually sway as much as a meter in the wind, damping devices incorporated into the design meant that such an extreme amplitude would quickly diminish to an acceptable value.

Tower, which consists of a collection of nine framed tubes with a footprint suggestive of a tic-tac-toe grid, making it a so-called bundled tube. The weight of a typical framed tube is borne by two sets of steel columns, one around the perimeter and one clustered in the core of the building, where stairwells, elevator shafts, and lobbies, as well as the essential utility conduits and restrooms, are located. In the 63-metersquare footprint of the World Trade Center towers, this arrangement left the 18-meter distance from the central core to the outside wall free of any structural

down the building by damaging what they thought were critical structural supports. Other than the explosion leaving some dangerously unbraced columns and causing a good deal of smoke damage, the building continued to stand tall even in its compromised state, thus attesting to its redundant design. The robustness of the structural design was also demonstrated during the terrorist attacks of September 11, 2001, when the badly damaged towers stood for an hour or so after the hijacked aircraft took out numerous perimeter columns. The buildings might have stood even longer, and maybe not have collapsed at all, had the fireproofing on the steel columns not been destroyed by the impact or had the fire been contained. One of the factors that impeded first responders from gaining access to the damaged floors was the crowds of people rushing down the same stairwells that firefighters were running up. Access—ingress, egress, and nearness—is something that has not always been given sufficient thought in the design of a building, but it is something that draws attention in the wake of a tragedy. After the truckbomb incident, vehicle access to the underground garage and human access to the building itself were severely restricted. (In 1995, just two years after the first World Trade Center attack, a truck bomb went off in ZUMA Press, Inc./Alamy Stock Photo front of the Alfred P. MurDuring the COVID-19 pandemic, elevators worldwide have been outfitted with signs and rah Federal Building in Oklahoma City. floor markings to indicate proper social distancing in the enclosed spaces. In the wake of what had happened in New York, the likeliness of a terrorist atTubular Design obstructions, thus allowing for an open tack on the Oklahoma structure should The form of structure Robertson chose floor plan. In the mid-1990s, during a have been viewed as credible. The buildfor the towers is known as a framed visit to the Port Authority’s chief engi- ing’s facade was supported by widely tube. At the time, it was a relatively new neer, Eugene J. Fasullo, who occupied spaced columns located very close to way to build tall without having a for- prime office space in the North Tower, the street. Had strict limitations on parkest of columns breaking up the interior I saw how this open space was filled ing there been enforced, the explosivesspace. The system was developed by with a crop of cubicles, whose occupants laden truck might not have been able to the Chicago-based architecture and en- should not have felt as claustrophobic as get close enough to be so effective.) gineering firm of Skidmore, Owings they might have in cramped, windowAn Easy Lift & Merrill. Among their tubular build- less inner offices. ings contemporary with the New York My visit took place not too long after Even modestly tall buildings would World Trade Center were the John Han- a truck bomb had exploded in an open- not be practical without the concept of cock Tower, which is distinguished by access underground parking garage, an elevator. The basic idea goes back to its sloped sides and exposed diagonal leaving a crater several levels deep. Evi- ancient times, when humans and draft bracing, and the Sears (now Willis) dently, terrorists were hoping to bring animals provided the motive power www.americanscientist.org

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technical services floors

Sky Lobby floor for transferring from express to local elevators

technical services floors

plaza level

Barbara Aulicino

express elevators

local elevators

balanced ventilation shafts

office space

The World Trade Center towers were designed with all of their stairwells, elevators, and other facilities at the center of the structure to maximize office space (above). The elevators were set up with express cars (green) to “Sky Lobbies” (blue) from which local elevator banks (yellow) were accessible (top).

through windlasses to lift buckets of ore out of mines. In the 19th century, elevators in the form of platforms were raised and lowered by steam power. When an elevator was used to lift such inanimate goods as coal and warehouse supplies, safety was mostly a matter of inconvenience. When a hauling rope broke—a not-infrequent occurrence—it was simply replaced with a fresh one and the scattered and damaged goods salvaged. 150

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Going from lifting replaceable loads to lifting human beings introduced new concerns for safety, not only because a free-falling elevator car could result in severe injury or death, but also because buildings did not want to face costly litigation. Such considerations led inventor Elisha Otis to develop his automatic emergency brake, which he demonstrated in the 1853 World’s Fair in the New York City exhibition space known as the Crystal Palace. Four years later, a safety passenger elevator was installed in a building on Broadway in Manhattan. On the day I visited the World Trade Center’s North Tower, the lobby was outfitted with check-in booths much like those found in a venue hosting a large conference. Before I could even approach the elevators, I had to produce identification and have my appointment confirmed. The elevator system for a supertall building housing on the order of 10,000 office workers and guests was another limiting design factor. At the time, a rule of thumb was that as much as 30 percent of a building’s volume had to be allocated to banks of elevator shafts and their adjacent lobbies. Because return on investment depended largely on how much office space would be rentable in a building, it was desirable to maximize the amount and quality of usable interior real estate and minimize that devoted to unrentable common space. For the Twin Towers, it was this objective that drove the design decision to locate all stairways in the core of the structure, thus leaving the perimeter for prime window and corner-office space. The Empire State Building has 73 elevators to serve its 102 floors, which collectively amount to 200,000 square meters (2.5 million square feet). Extrapolated to a single World Trade Center tower, which contained about twice the square footage, its size meant that as many as 150 elevators might have been needed. To be economically viable, an alternative to having a dedicated shaft for each elevator had to be found. One way of doing so was to use double-decker elevators and to have multiple elevators share a single shaft, in a vertical system of express and local elevators akin to the horizontal scheme used for trains in the New York City subway system. The World Trade Center building was divided into stacked zones, each upper one accessible by express elevators from the ground floor and a mezzanine lobby (reached by escalator), as well as a Sky Lobby, where passengers transferred to

a local elevator that served the floors in its zone. The system, although potentially confusing for a first-time visitor, was efficient for its time and place. Reduced Capacity Amidst the current COVID-19 pandemic, a renewed focus has been put on elevators, even those in buildings nowhere near skyscraper height. The New York City Building Code, for example, defines a high-rise as a building greater than 22 meters (75 feet), or roughly eight stories tall, which is about the maximum height that a fire truck’s ladder can reach. Few people would wish to climb up that many flights of stairs to reach their workplace in the morning or their apartment in the evening. Thus, even much lower-rise office and apartment buildings are equipped with elevators. But an elevator car or cab is a communal place of assembly, and even a ride of short duration can be fraught with anxiety over who in the car previously or among current fellow riders might be infected with the SARS-CoV-2 virus. Naturally, this kind of concern has changed elevator ride regulations, as well as the behavior of some elevator riders, especially those in high-risk classes. Some people, especially those in buildings with smaller elevators, have adapted to the new normal by waiting for an empty car, and perhaps even carrying disinfectant materials into it when it arrives. If another person gets into the car before it departs, a person concerned about aerosol transmission may even exit before the doors close. Municipal governments, along with elevator designers and service companies, as well as building managers, condo and co-op boards, and resident committees, have tried to respond to pandemic concerns by regulating the number of passengers in a car at one time. A considered occupancy limit should naturally depend upon a car’s size, meaning it could be as small as a single individual or a single family group. Signs announcing capacity have been posted beside and inside elevators, but just as not everyone wears a face mask, not everyone adheres to such restrictions. How can they be enforced, other than by a compliant passenger exiting the car? There have been low-tech efforts to maintain social distancing by marking lobby and elevator floors with proper spacing indicators. Thus, passengers in a large elevator car might be positioned on marks like X’s and O’s on a tic-tac-toe

Courtesy of MAD Elevator Inc

Carolina Jaramillo Castro/Alamy Stock Photo

New touchless elevator technologies under development include buttons with proximity sensors (left) and floor-level kick buttons (right) to call elevators. As a stopgap, some elevator riders have adopted the use of a stylus for pushing buttons (middle).

grid. Still, riding in a closed, windowless room with poor ventilation makes it difficult to abide fully by such sensible rules. A newly entering passenger may have to reach around someone standing close to the control panel to register her floor. Asking that person to do it, as used to be common practice, is now asking that person to touch buttons more frequently than he may wish. Furthermore, every new passenger to an elevator that is already almost fully socially distanced will face the problem of positioning himself among passengers who have staked out their own positions. Will existing passengers move to the rear to make room for the newly added occupant? If they do, they may have to break social distancing guidelines later by pushing their way through a crowd to get off at the proper floor; if they do not, the entering passenger will have to pass closely between them. These are not strictly technical questions; they are questions of social design, which can be more difficult to answer. Crowd Control Controlling how many people are allowed in an elevator does not solve the related problem of crowds accumulating in the lobbies of large office buildings when employees show up during the morning rush hour. Indeed, it can exacerbate it. Fortunately, having many employees work from home during a pandemic greatly reduces the passenger load on elevators. For those employees who cannot work virtually, staggered work hours can go a long way toward achieving the same effect in the office. To prevent an entire floor from going out to lunch at the same time, one solution has been pop-up snack carts that can be scheduled to bring lunch to the floor. www.americanscientist.org

Some buildings and businesses have even gone so far as to assign elevator boarding times. Workers who show up outside their reservation window have to wait for a standby lift spot—at a proper social distance, of course. Some potentially offensive practices can be obviated by hard (and soft) technology. Summoning an elevator and

Technological upgrades to elevators may have to be considered longterm investments. directing it to a specific floor used to be a simple act of pressing a button or two. But when touching a potentially contaminated surface was discouraged, that became a potentially risky act. It could be avoided by wearing gloves or poking the button with a makeshift stylus or any one of the many “antitouch” gadgets that have become available. The shape of most of these hastily designed all-in-one keychain gizmos is graceless, but so was the design of the so-called church key that was needed to open a beverage bottle or can before the advent of twist-tops and pop-tops. Some lower-tech options in development include copper buttons, as copper is known to kill off microorganisms, and floor-level buttons that are kicked instead of touched. Touchless technology that is wellestablished in other areas has been adapted to some elevators. We are accustomed to using touchless touchscreens at airport check-in kiosks that employ heat-sensing buttons to

Courtesy of MAD Elevator Inc

register a choice even before a finger touches the keypad. There are also voice command features, such as those incorporated into television apps, automobile navigation systems, smartphones, and the like. Such technology is not difficult to incorporate into retrofitted elevator systems, but it comes at a price that an operator of a building or its tenants have to decide is worth paying. Some elevator companies are working on smartphone apps that building occupants could download to call wirelessly for an elevator, check if it is occupied even before its doors open, and have it not respond to other potential passengers until the current one has exited. Recently adapted technologies involve disinfectant systems that become activated when an elevator is sensed to be empty. They can take the form of bathing the car in ultraviolet light—a technology already established in disinfecting water supplies—or spraying it with disinfectant between passenger loads. Risk-benefit and cost-benefit analyses of developing and adopting such prophylactic conveniences are complicated by our limited knowledge of the virus itself, by changing guidelines about how to respond to it, and by how long a pandemic will last. The cost of installing smart systems may be prohibitive for smaller buildings, or too disruptive for really large ones financed by investors who expect a certain return on their investment. But because there seems to be increasing concern that if not this virus, then some other one will attack the population in future years, such technological upgrades to elevators may have to be considered long-term investments. However, like any design decision, these ones will involve a lot of judgment calls, including who will pay for them—the government, the landlord, or the tenants? Q 2021

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Arts Lab

Tinkering with Crystals The beautiful and fragile crystallized creatures from Tyler Thrasher showcase his artistic attitude of serendipity, exploration, and staying fascinated with the world. Artist Tyler Thrasher has a big personality, and he’s not going to tone it down. Indeed, his genuine enthusiasm and fascination are some of the hallmarks that have catapulted him to artistic success. Based in Tulsa, Oklahoma, Thrasher is best known for growing crystal formations on organic remains, especially cicadas, but his endeavors don’t end there. He also hybridizes plants, makes music, and produces clothing for Black Lives Matter fundraising. Thrasher developed and donated hundreds of science kits to children in underfunded schools. His current work is an installation of ghostly bleached plants and insects at the Philbrook Museum of Art in Tulsa. Thrasher discussed his explorative approach to science-inspired art with Editorin-Chief Fenella Saunders.

like to be in those boxes with it. Now, when I share my experiments or my hybridizing of plants, one response I usually get is, man, I wish I had you as a science teacher. I don’t think I’m doing anything special. I’m just doing what I enjoy, and I’m sharing how I do it. I wish there was more of that in science, where we encourage kids to view science as an everyday thing, not just a sit-in-a-room-with-a-book thing.

What got you interested in science? My dad was a landscaper. I grew up surrounded by plants. My dad had these absolutely mesmerizing gardens that I would often explore. So as a kid I spent a lot of time exploring in nature, literally in my own backyard—a lot of time exploring and tinkering. My degree is actually in computer animation and art history. Anything I do with science is mostly self-taught, a fun sort of side venue for my creative expression. What are your thoughts on how people can better see science as not just something you learn in school, but something you experience? When I was growing up, school was like, here’s the book, here’s the chapter, here’s the test. But looking back, I was doing science every day, when I was left to my own devices in the natural world. I just didn’t call it science. It was an escape, or it was me being fascinated. I do think science comes naturally to most people, but we don’t 152

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How did you combine your art background with your interest in caving and mineralogy to get where you are? I doodled throughout school, but my art fascination started with a supportive high school teacher. In college I went on a caving adventure. My first cave experience was like my mind was just catapulted. If you spend enough time underground, isolated from other humans, you start to view the world a little differently. I started looking at all

these old structures, which outdated anything I had learned about in history class. I found myself drawing crystals and minerals I’d seen in a cave. I even started shading my art in ways that resembled mineral formations or textures. Next thing I knew I thought, what if I grew my own crystals? I had a chemistry background from high school, so I knew how to grow crystals. What if I grew crystals on something that’s not expected? Not rocks. I found a little cicada shell outside and I wondered if I could grow crystals on an insect exoskeleton. Would the body break down? Would it react? There were no papers or journals on crystallizing insect carcasses; the only way to find out was to try it. I downloaded free science

Artist Tyler Thrasher uses his own solutions of compounds that form crystals of various colors, shapes, and sizes, and immerses organic remains such as a beetle (below) or a dragonfly (opposite) in the solutions to grow the structures that make each of his artworks. (All images courtesy of Tyler Thrasher.)

journals where I could. I’d buy old college textbooks and just sift through and gather notes. I crystallized a cicada shell, and the first time I saw it, again, my mind was just enraptured. I shared an image of it on the internet, and it didn’t take long before other people also thought it was the craziest

thing they’d ever seen. It became my full-time job, mostly just because I explored. I had something I was curious about, and I just did it. It changed my life completely. www.americanscientist.org

How would you describe your artistic aesthetic? I think for me the way I categorize my art is just how can I take the atoms around me and make something new? How can I use the natural world around me as a palette, like a box of brushes and paints? How can I look at the world like a big Lego box and tinker and have fun? I never really stopped to say, where does my art fit? I think science art is a good mix, but I really think I’m just tinkering and having fun. When you first started crystallizing things, was that easy? There was a lot of trial and error at first. That’s mainly my fault. I don’t like instructions. I like to just try things on my own and learn all the ways to go wrong. After that it became really easy. Growing crystals is as simple as taking a compound that deionizes in water, supersaturate the solution, put something in it, and

crystals will nucleate and grow. All systems are looking for equilibrium. Once you understand that, my job as an artist is to destroy the equilibrium, add a dollop of chaos—that’s literally what dissolving and breaking down compounds is—and watch how the chaos can make something new. Crystal nucleation points are basically imperfections, places where something can grab hold. Does that figure in your work, that you’re using imperfections to make art? That’s the big one. In a way, yes, it’s me relying on the natural imperfections of organic objects. Cicadas have all these grooves and scratches on the exoskeleton from having survived in the wild. Every scratch or ding is a spot where a molecule can rest and pull in other molecules and crystallize around it. In a fun way, my art does heavily rely on imperfections to make something visually satisfying. 2021

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Thrasher immersed this cicada in a solution of potassium ferricyanide to produce these bright red salt crystals on its surface.

Do you have any insights to why crystals grow larger in certain places than others? There are so many theories. There’s a lot going on in any given vat. One example I could offer is say I float a cicada on the top of a crystal vat. The way I set the cicada in, some of the solution goes over one of the wings. The wing gets a little waterlogged and the cicada tilts at an angle. All of a sudden, that half of the cicada is breaking the surface tension enough that it forms this vacuum where, when crystals start to grow on the surface of the solution, they’ll follow that flow line where the surface tension is breaking and flow to that part of the cicada. Then once those crystals grow, all of a sudden they’re pulling in more molecules. Sometimes if the cicada comes out more crystallized on one half than the other, that’s why. That’s all dependent on how many pieces are in the vat, what’s on top of what, how things are sitting there in the solution, that attracts and controls where crystals grow and how the molecules and ions move in that system. Do you ever try to control that, or do you leave it to chance? Scientifically I know exactly what’s going to happen, but it leaves this tiny 154

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little margin for surprise, where every now and then, maybe one in every 200 pieces I make, something happens that I didn’t expect, and it’s so inspiring. So I don’t control it, because that tiny margin of surprise is kind of what I live for when it comes to making art. The colors that you get are all done just by using different chemicals? It’s all dependent on the molecule and how it interacts with light. I don’t add any dyes. I just pick the piece and pick the chemical based on the color the crystal will be and go from there. How do you think that art and science overlap and fit together? For the most part I think they’re the same thing, just with different goals. Art and science are the human brain’s way of understanding the world in reality around us. Both are trying to communicate reality to some degree. Art can be a catalyst for emotion, conversation, dialogue, political movement. More of those abstract ideas that don’t provide hard answers. And science sometimes wants to do that, but science has to have the hard answers. The difference is, both routes require a human to look at the world around them, be curious and want

answers, but art doesn’t necessarily give you the answer. Science’s job is to always look back and always be doubtful and always refine, refine, refine. The point of art isn’t to look at everything you did wrong and go and make it better necessarily. But I do think both schools largely deal with trying to understand and communicate the world around us. Both scientists and artists do exactly this. How can we find a balance between learning standard techniques and still keeping creativity and personal direction? I think we need both. The formal education shows us the toolbox. Here are some tools. They’ve been around for decades. This is how you can use them. But I want to see fewer limits on what those tools can do. We can’t just go out into the world without tools and come out a mess or do something crazy and hurt ourselves. We should be shown what the tools are and told and encouraged that these tools are for us to use how we want to use them. Do you feel that you want to be a role model for science outreach? I do want to encourage people to explore the world. It’s your world. It’s

your home. Have fun. But there is always this looming goblin behind me from bigger institutions or even other scientists who have messaged me to remind me that I’m not a real scientist. I’ve had people who’ve told me that I’ve encouraged science in their lives more than their science teachers did. I do find comfort where I see there are leading scientists who have faced opposition and criticism, but have led some groundbreaking work. If they can survive that, then maybe I can get myself together and come in with my little science flag too and say what I need to say. You give yourself a mad scientist label, a bit as a joke. But do you think that perpetuates the idea that madness is required to have creativity in science? There are times when I’m in my lab and if something works and I put it under the microscope, I will literally jump up, scream, hop on my skateboard with my lab coat, and do laps while shouting in joy. On the outside, someone would look and say, that dude is mad. And I’m like, no, you don’t get how cool the world is! I think the mad part is just another synonym for—I don’t know, madly inspired. So I think the mad part is just me trying to contain how cool I think the world is. You had a lot of involvement in 2020 with Black Lives Matter. What are your thoughts on increasing trust and inclusion in science? Growing up as a BIPOC [Black, Indigenous, and people of color] American, very poor, and having friends who grew up in North Tulsa, which is largely a Black community that’s very underserved, science is not a priority. The priority, we’re told, is survival. A lot of Black Americans are in a place where we don’t feel like we can afford Thrasher does not control the pattern of crystallization in any of his pieces. Crystals form on nucleation sites, imperfections in the surface where the molecules can grab hold. Sometimes this leads to large growths in one small area of the subject (bottom). The size, shape, and color of the growth depend on the solution used (potassium chromium sulfate is purple, and ammonium iron sulfates are pale green) but also have an element of chance, because of the random texture of natural surfaces. The role of imperfections and serendipity in producing beautiful pieces is a factor that Thrasher embraces in his art. www.americanscientist.org

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Thrasher holds one of his crystallized snail shells (top), hundreds of which he sold for $1 each to reach people economically impacted by the pandemic. One of his larger pieces, a snake skeleton (above), includes blue crystals of ammonium copper sulfate. 156

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Thrasher used a solution of potassium chromium sulfate to grow crystals on this fish skeleton, with some of the crystal growth nucleating toward the tips of some of the spines.

to stop and look at things like science and the arts and all this stuff that gets higher up on that hierarchy of needs. Science isn’t prioritized in school with Black kids. It comes down to teachers who can encourage that, and they have to have those uncomfortable conversations. They have to stop and look at their Black students and say, “You could be a scientist.” I was one of three Black kids in my chemistry class, and we were kind of ostracized. We make these adventure kits, and we want to go to underserved communities and schools where they don’t have those activities and give a bunch of kids just a bag with tools in it and say, “Let’s go on a hike for two hours. What do you find?” Something as simple as that, encouraging exploration within the BIPOC community, that’s a big deal. We’re not shown that we’re allowed to explore. We’re not really shown that this is our world. When you take people and tell them that this isn’t really where they belong, why would they feel the need to explore it and do science, which is largely exploration? We need to change how we talk to Black kids about their possibilities and open it up for them to be able to explore the world. Are you hopeful about change? I think I’m a pretty optimistic, hopeful person when it comes to change. Humans, we’re really young. Science is even younger. I think we’re going to get to a point, hopefully, where we www.americanscientist.org

will get things back on track. We’ll consider other ways to look at science and approach it, and listen to other types of scientists. How do we scientifically view what is science? All these conversations are happening. So I do remain very hopeful that the conversation will change and humans will get it together, because we’re all essentially just celestial toddlers trying to figure this whole thing out. We have not been here very long. We’re just a bunch of molecules, chaotically zipping through space and time. We’ll get there. We’ll figure it out—just not overnight. You have listed hundreds of crystallized snail shells for $1 each and donated hundreds of science kits. Who do you reach with those programs? I got all these emails from hundreds of people who said, I really want some of your art, I was really hoping for it this year, but then I lost my job, or I have kids that haven’t been in school. A lot of people have had a bummer year. I thought it would be really nice to share this. I decided to list 200 snail shells for a dollar, and either it’s adults who lost their jobs or parents who have kids who have been sitting in the house all year looking at a computer. They need something to inspire them or spark their imagination. Parents got snail shells just to give them to their kids, give them something to say, “Whoa!” If you can just say “Whoa!” once this year—just

any tiny sparkle we can get—there’s that. And then with the science kits we did earlier this year, I put together some chemistry kits, and we went into North Tulsa. I know some schools here that just don’t prioritize science because they don’t have the funding or encouragement. We went to their front porches and dropped off around 100 science kits. For me it’s just for whoever needs it. What makes art successful? That is a question. I think it’s a mixture of character, probably resourcefulness, and a little bit of luck. Once I found my community and reached out to those people, they started to reach out to like-minded people. Once you see something working, it’s like growing plants: You have to tend to it and pay attention. On top of all that, you have to be a semi-decent human, too. It’s a mixture of, what do you give back? Do you use your art to connect with others, or is it more self-indulgent? What’s the purpose of your art? Does it make people feel good? I think it’s just being genuine. It’s scary to be yourself, because we’re afraid of being rejected. I’m this crazy, excited, loud, energetic individual, and I’m not going to be quiet to make people comfortable. I think a lot of people respond well to artists being themselves and making the art that they believe in. Thrasher talks about taking chances, growing opals, and more in an extended interview, available online.

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Enter the Axion A new fundamental particle could solve a major puzzle in particle physics—and also explain the nature of the dark matter that permeates the universe.

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here are two ways to start a story about the axion. One is to explain that this hypothetical particle could be the key to a major problem in the Standard Model of particle physics, which describes all of the known fundamental particles. The beauty of the axion is that there is a second, equally significant beginning to its story. We now suspect the axion may also be the answer to one of the most important questions—if not the most important question—in all of particle physics and astronomy: What is dark matter? Dark matter is the term that researchers use for the invisible substance that seems to dominate the formation of cosmic structure and to make up the majority of all tangible matter in the universe. The first thing I like to tell people about dark matter, to help them develop some intuition for this strange idea, is that dark matter is a terrible name for this stuff, whatever it is. The term is often attributed to Swiss astrophysicist Fritz Zwicky, who proposed the existence of dunkle Materie in 1933, but in fact the first articulation of something like it goes back to 19th-century scientist William Thomson, better known as Lord Kelvin. In 1884, Kelvin first spoke of “dark bodies,” proposing that there might be celestial objects that do not radiate light or other energy, making them difficult to detect with our astronomical instruments. The modern conception of dark matter draws on this apparently intuitive idea that something that does not radiate is dark. But the dark matter problem we are dealing with is much

more fantastic than that: We are contending with a type of matter that simply does not interact with light or other radiation. This property is why dark matter is a terrible name: We can see matter that is dark. We can see dark hair, for example, when light scatters off it into our eyes. A better name would be invisible matter, transparent matter, or clear matter. The first substantive evidence for the existence of dark matter came from the work of astronomer Vera Rubin in collaboration with Kent Ford. Using an instrument Ford developed, Rubin looked at the speeds of stars as

Today, there is a plethora of evidence for the existence of this missing dark matter. Besides Rubin and Ford’s galaxy rotation curves, we now know plenty about clusters of galaxies, galaxy mergers, and other aspects of cosmic structure formation. Moreover, our evidence goes beyond the galactic and even comes from a time long before galaxies had formed. Data from cosmic microwave background (CMB) radiation—the first light to travel freely in a transparent universe after the post–Big Bang plasma cleared—match best with a model that includes dark matter. Indeed,

We are contending with a type of matter that simply does not interact with light or any other form of radiation. they orbited the center of their galactic homes. What she found was inconsistent with what one might expect based on estimates of the galaxy’s mass that researchers made by using stars. If the stars were all of the matter in the galaxy, they should have been orbiting more slowly. The stars were moving as if there was more matter than astronomers could see. In other words, the data indicated that there was a lot of matter on the outer edges of the visible parts of the galaxy—matter that wasn’t radiating but was nonetheless gravitationally influential.

CMB data are currently the strongest evidence for dark matter. We also know that dark matter is a totally different substance from any of the particles in our elaborate Standard Model of particle physics. The best way to develop an intuitive feel for this concept is to understand that most of those particles would radiate in ways that dark matter does not. No particle in the Standard Model has the right properties to be the dark matter. The idea that most of the matter in the universe is something we’ve never seen or touched might seem

QUICK TAKE The Standard Model is a powerful but incomplete theory of particle physics. The axion could deepen our understanding of the model and explain a puzzling asymmetry within it.

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Unlike familiar protons and electrons, axions would not interact with light. Axions could be the invisible “dark matter” that seems to guide the formation and structure of galaxies.

Physicists are running experiments to find direct evidence of the axion. The author is also studying the axion’s theoretical properties and its possible astronomical effects.

NASA, ESA, D. Harvey (École Polytechnique Fédérale de Lausanne, Switzerland), R. Massey (Durham University, UK) and HST Frontier Fields

Chanda Prescod-Weinstein

Galaxy cluster MACS J0416.1-240 contains far more mass than its visible stars and gas can account for. Scientists infer the location of the unseen matter (indicated in blue) by the way it distorts the light of more distant galaxies, but its nature is entirely unknown.

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dark energy 68.3%

dark matter 26.8%

ordinary 4.9% matter

Barbara Aulicino; ESA and the Planck Collaboration

The composition of the universe is written in the sky, encoded in the cosmic microwave background, relic radiation from the Big Bang. An all-sky map based on data from the Planck space telescope shows that the radiation is warmer (red) in some places and cooler (blue) in others. The pattern of variation confirms the presence of abundant dark matter; ordinary matter alone cannot match the observations.

implausible. How do we know it’s there? Is it truly the case that we, along with stars, dust, and everything else that is luminous, are a demographic minority in the universe? Spend some time thinking about these questions, and you may find it difficult to stop. This could seem like a problem to someone who isn’t a scientist, but from the point of view of a theoretical physicist, it is a wonderful problem to have. A Massive Problem Over the past several decades, many theoretical physicists have taken up

underground detectors such as Large Underground Xenon (LUX) in South Dakota and XENON1T in Italy. The lack of a discovery or even a hint of discovery during the past decade sent many physicists back to the drawing board in search of a new dark matter particle to research. As a result, over the past few years one candidate that can be detected through other mechanisms and had previously garnered relatively little attention has swelled in popularity: Enter the axion. I didn’t always believe that dark matter was so important. In fact, I used to

There was new physics out there waiting to be theorized. The axion emerged from one of these searches. the task of trying to solve the dark matter problem. Accounting for all of the hypothetical particles proposed to explain it is like trying to describe all the denizens of an enormous menagerie. For a while, many researchers placed their hopes on candidates inspired by a theory called supersymmetry. These models were tested using CERN’s Large Hadron Collider or in giant 160

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think dark matter was a boring, fringe problem in particle physics that would get sorted soon enough. For a long time I thought the only great challenge of our time was cosmic acceleration, perhaps because scientists discovered it the year I applied to college. It’s easy to think my youthful ignorance drove this, but it’s also the case that everywhere I looked, there were exciting conversations about

dark energy happening. (Despite their similar-sounding names, dark matter and dark energy are ideas that address distinctly different problems.) During the summer after my first year of college, I had the opportunity to spend a few months doing research in particle physics. During that time, I had the opportunity to visit Fermilab, where I saw a talk by distinguished theoretical physicist, Edward “Rocky” Kolb. It was 2000, just two years after astronomers had discovered that the universe is not only expanding, but that its expansion is also accelerating. Reconciling this new empirical data about cosmic acceleration with our best theoretical framework for gravitation— general relativity—led to the idea that space is filled with an unseen energy known as dark energy. As a result, Kolb opened his talk—to the best of my recollection 21 years later—by saying that cosmologists had worked out the universe’s composition. It was 5 percent “normal” everyday matter, 20 percent dark matter, and 70 percent dark energy. We were almost there, he said. We just needed to figure out what dark matter and dark energy were, and we would be done. It’s a funny story, and part of what’s funny about it is that I figured we’d soon find dark matter and that dark energy was the only real mystery. Dark matter has a way of drawing you in though, and for me the tug came through axions. Today I am known by colleagues around the world to be an expert on this particle. To understand how a scientist like me gets captured by a particle that isn’t even necessarily real, it’s important to go back to that particle’s origin story— to the strong CP (charge conjugation and parity) problem. Cracks in the Standard Model The axion began as a solution to a problem in the Standard Model of particle physics—specifically, the part built on the theory of quantum chromodynamics (QCD), which governs the fundamental particles we call quarks and gluons. QCD is highly successful, but it predicts properties we’ve never seen in the neutron (which is made of quarks). To understand that problem, it’s important to know some basics about the math behind the elaborate artifice of the Standard Model. There is a specific recipe for writing down new ideas in particle physics.

Barbara Aulicino/photos Andrey Elkin; janniwet wangkiri/Alamy Stock Photo; UK Open Educational Resources/CC BY-NC-SA 2.0

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B Symmetry is a ubiquitous aspect of everyday physics. If a symmetry is broken—if a mirror reflection looked different than the object being reflected—it would indicate an unexpected process at work (above). The same is true in particle physics, as shown in an experiment with electrons emitted by radioactive cobalt atoms (right). The decay process breaks mirror or parity symmetry (P), which reveals a deeper symmetry of parity plus charge (C). Another type of symmetry breaking predicts the existence of the axion.

We use an equation that we call the Lagrangian that is meant to characterize a particle’s properties and from which we can derive the equations that predict the particle’s behavior in space and time. The most fundamental ingredients for this equation are components that describe the different types of energy that characterize a particle. Additional “spices” include how the particle interacts with other particles. As with baking, there are very specific rules about how to add these components and to make sure that they don’t do too much or too little. Many of these rules are built on the expectation that each term in the Lagrangian will remain the same if we carry out a mathematical operation associated with a symmetry on them. This process might sound complicated, but we are very familiar with symmetries in our everyday lives. A circle, for example, is symmetric: No matter how we rotate it, every spot on the circle is the same as every other spot. In other words, when you rotate a circle around its center, it will always look the same. This property is a rotational symmetry. The symmetry can be broken if, for example, I draw a dot in one place on the circle. Now there is a www.americanscientist.org

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special place on the circle, and rotating the circle changes the location of the special place. An example of a symmetry we might require a Lagrangian to have is time-translation invariance—that is, if we change the time interval we put into the equation, the answer remains the same. The Earth’s gravity is the same day and night. It is time-translation invariant. If a term that we are thinking about adding to the equation doesn’t respect a symmetry that we know or theorize to be important, we discard that term. If your hypothesis contains an equation indicating that gravity changes from time to time, it is dead on arrival. From a physical standpoint, these symmetries imply the existence of conservation laws, ensuring that, for example, we can’t create an electric charge out of nothing. From a mathematical perspective, the Standard Model is a lengthy Lagrangian with many terms, describing all of the particles we have ever seen. Scientists have developed this formulation of particle physics through a mix of theoretical and experimental trial and error. Where experiment hinted at the need for new terms, theorists wrote down models with hypothetical sym-

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metries and checked if they matched the data. Sometimes these models matched the data but indicated there were more particles out there, yet undetected. Sometimes models matched the data, but then new data came in suggesting that the model wasn’t rich enough: There was new physics out there waiting to be theorized and observed. The axion emerged from one of these searches for new physics. Small Fix, Big Implications The dynamical relationship between theory and experiment has led to many successful developments in particle physics. One example is the discovery of the top quark, which was predicted in the 1970s but wasn’t observed until 1995. Starting in the 1960s, experiments with an unusual particle called a kaon indicated that when it decayed, there were violations of charge conjugation parity (CP) symmetry. This symmetry has two components: Charge conjugation symmetry is the phenomenon where the physics of the system remains the same even if the sign of the particle’s charge changes from positive to negative or vice versa. A phenomenon or object that has parity symmetry has the same 2021

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