CINXE.COM

<!DOCTYPE html><html lang="en" dir="ltr"><head><meta charSet="utf-8"/><meta name="viewport" content="width=device-width,initial-scale=1"/><link rel="icon" href="https://cdn.theatlantic.com/_next/static/images/favicon-3888b0e329526a975703e3059a02b92d.ico"/><link rel="apple-touch-icon" href="https://cdn.theatlantic.com/_next/static/images/apple-touch-icon-default-b504d70343a9438df64c32ce339c7ebc.png"/><link rel="apple-touch-icon" sizes="76x76" href="https://cdn.theatlantic.com/_next/static/images/apple-touch-icon-76x76-d5accc11b8265af76495fbfa9d38dd3b.png"/><link rel="apple-touch-icon" sizes="120x120" href="https://cdn.theatlantic.com/_next/static/images/apple-touch-icon-120x120-419ba228184c040a691628d3dd82c206.png"/><link rel="apple-touch-icon" sizes="152x152" href="https://cdn.theatlantic.com/_next/static/images/apple-touch-icon-152x152-aafde20dd981a38fcd549b29b2b3b785.png"/><meta name="application-name" content="theatlantic"/><meta name="msapplication-TileColor" content="#FFFFFF"/><meta name="msapplication-TileImage" content="https://cdn.theatlantic.com/_next/static/images/apple-touch-icon-default-b504d70343a9438df64c32ce339c7ebc.png"/><meta property="og:site_name" content="The Atlantic"/><meta property="og:locale" content="en_US"/><meta property="fb:admins" content="577048155,17301937"/><meta property="fb:app_id" content="100770816677686"/><meta property="fb:pages" content="29259828486,1468531833474495,1061579677251147,457711054591520,370457103090695,1631141167169115,148681772342453,1510507419185410,128344747344340,128377530562508,236061986423933"/><meta name="p:domain_verify" content="68e1a0361a557708fefc992f3309ed70"/><meta name="twitter:site" content="@theatlantic"/><meta name="twitter:domain" content="theatlantic.com"/><script type="application/ld+json">{"@context":"https://schema.org","@type":"WebSite","name":"The Atlantic","url":"https://www.theatlantic.com","inLanguage":"en-US","issn":"1072-7825","potentialAction":{"@type":"SearchAction","target":"https://www.theatlantic.com/search/?q={q}","query-input":"required name=q"}}</script><script type="application/ld+json">{"@context":"https://schema.org","@type":"Organization","@id":"https://www.theatlantic.com/#publisher","name":"The Atlantic","url":"https://www.theatlantic.com","logo":{"@type":"ImageObject","width":{"@type":"QuantitativeValue","unitCode":"E37","value":224},"height":{"@type":"QuantitativeValue","unitCode":"E37","value":224},"url":"https://cdn.theatlantic.com/assets/media/files/atlantic-logo--224x224.png"},"sameAs":["https://www.facebook.com/TheAtlantic","https://twitter.com/theatlantic"]}</script><style id="_vis_opt_path_hide">#paywall,#nonMeteredNudge,#gate {opacity:0;}</style><title>An Existential Problem in the Search for Alien Life - The Atlantic</title><meta name="description" content="We don’t really know what life is in the first place."/><meta property="krux:title" content="An Existential Problem in the Search for Alien Life - The Atlantic"/><meta property="krux:description" content="We don’t really know what life is in the first place."/><link rel="canonical" href="https://www.theatlantic.com/science/archive/2023/12/defining-life-existentialism-scientific-theory/676238/"/><link rel="image_src" href="https://cdn.theatlantic.com/thumbor/rXrDmLpYn-O_Vd5Bj8qbzKpzLPU=/0x43:2000x1085/1200x625/media/img/mt/2023/12/what_is_life_/original.jpg"/><meta name="author" content="Jaime Green"/><link rel="ia:markup_url" href="https://www.theatlantic.com/facebook-instant/article/676238/"/><meta property="article:publisher" content="https://www.facebook.com/TheAtlantic/"/><meta property="article:opinion" content="false"/><meta property="article:content_tier" content="metered"/><meta property="article:tag" content="science"/><meta property="article:section" content="Science"/><meta property="article:published_time" content="2023-12-05T12:00:00Z"/><meta property="article:modified_time" content="2023-12-05T17:45:56Z"/><meta name="robots" content="index, follow, max-image-preview:large"/><meta property="og:title" content="An Existential Problem in the Search for Alien Life"/><meta property="og:description" content="We don’t really know what life is in the first place."/><meta property="og:url" content="https://www.theatlantic.com/science/archive/2023/12/defining-life-existentialism-scientific-theory/676238/"/><meta property="og:type" content="article"/><meta property="og:image" content="https://cdn.theatlantic.com/thumbor/rXrDmLpYn-O_Vd5Bj8qbzKpzLPU=/0x43:2000x1085/1200x625/media/img/mt/2023/12/what_is_life_/original.jpg"/><meta property="twitter:card" content="summary_large_image"/><meta name="FacebookShareMessage" content="If humans stumbled upon life on another planet, would we even know it was living? @jaimealyse explores an existential problem in the search for alien life:"/><meta name="TwitterShareMessage" content="If humans stumbled upon life on another planet, would we even know it was living? @jaimealyse explores an existential problem in the search for alien life:"/><link rel="alternate" type="application/rss+xml" title="The Atlantic" href="/feed/all/"/><link rel="alternate" type="application/rss+xml" title="Best of The Atlantic" href="/feed/best-of/"/><meta name="referrer" content="unsafe-url"/><meta name="apple-mobile-web-app-capable" content="yes"/><meta name="apple-mobile-web-status-bar-style" content="black"/><meta name="apple-mobile-web-app-title" content="The Atlantic"/><meta name="keywords" content="signal of life, alien life, Sara Imari Walker, varied chemistries of other planets, life, extraterrestrial life, high clouds of Venus, product of life, Earth-based telescopes, small steps, spectral signature of phosphine, simple molecule, Lee Cronin, team of researchers, sign of a sign of life, philosopher of science Carol Cleland, small talk, life.But Walker, working definition, Signs of Life Found, closest possible home, much time, firm answer, Clouds Surrounding Venus, earthly life, drawing board, Arizona State University, self-organization, theories, decent way, chemistry professor, Walker’s unconventional approach, wavelengths of light, lot of room, renowned biologist Ernst Mayr, Walker’s view, theory of life, days of Aristotle, object’s smallest building blocks, number of examples, James Webb Space Telescope, search, Whole Time, Walker’s main collaborator, right things, only life, kind of understanding, way, Darwinian evolution, little orbits" itemID="#keywords"/><meta name="news_keywords" content="signal of life, alien life, Sara Imari Walker, varied chemistries of other planets, life, extraterrestrial life, high clouds of Venus, product of life, Earth-based telescopes, small steps, spectral signature of phosphine, simple molecule, Lee Cronin, team of researchers, sign of a sign of life, philosopher of science Carol Cleland, small talk, life.But Walker, working definition, Signs of Life Found, closest possible home, much time, firm answer, Clouds Surrounding Venus, earthly life, drawing board, Arizona State University, self-organization, theories, decent way, chemistry professor, Walker’s unconventional approach, wavelengths of light, lot of room, renowned biologist Ernst Mayr, Walker’s view, theory of life, days of Aristotle, object’s smallest building blocks, number of examples, James Webb Space Telescope, search, Whole Time, Walker’s main collaborator, right things, only life, kind of understanding, way, Darwinian evolution, little orbits"/><meta name="sailthru.title" content="An Existential Problem in the Search for Alien Life"/><meta name="sailthru.description" content="We don’t really know what life is in the first place."/><meta name="sailthru.tags" content="science,author-jaime-green"/><meta name="sailthru.date" content="2023-12-05T12:00:00Z"/><link rel="preload" as="font" type="font/woff2" href="https://www.theatlantic.com/packages/fonts/garamond/AGaramondPro-Regular.woff2" crossorigin=""/><link rel="preload" as="font" type="font/woff2" href="https://www.theatlantic.com/packages/fonts/graphik/Graphik-Regular-Web.woff2" crossorigin=""/><link rel="preload" as="font" type="font/woff2" href="https://www.theatlantic.com/packages/fonts/graphik/Graphik-Semibold-Web.woff2" crossorigin=""/><link rel="preload" as="font" type="font/woff2" href="https://www.theatlantic.com/packages/fonts/logic/LogicMonospace-Medium.woff2" crossorigin=""/><link rel="preload" as="font" type="font/woff2" href="https://www.theatlantic.com/packages/fonts/logic/LogicMonospace-Regular.woff2" crossorigin=""/><script type="application/ld+json">{"@context":"https://schema.org","@type":"NewsArticle","headline":"An Existential Problem in the Search for Alien Life","alternativeHeadline":"An Existential Problem in the Search for Alien Life","description":"We don’t really know what life is in the first place.","url":"https://www.theatlantic.com/science/archive/2023/12/defining-life-existentialism-scientific-theory/676238/","datePublished":"2023-12-05T12:00:00Z","dateModified":"2023-12-05T17:45:56Z","isAccessibleForFree":false,"hasPart":{"@type":"WebPageElement","isAccessibleForFree":false,"cssSelector":".article-content-body"},"publisher":{"@id":"https://www.theatlantic.com/#publisher"},"mainEntityOfPage":{"@type":"WebPage","@id":"https://www.theatlantic.com/science/archive/2023/12/defining-life-existentialism-scientific-theory/676238/"},"image":[{"@type":"ImageObject","width":{"@type":"QuantitativeValue","unitCode":"E37","value":720},"height":{"@type":"QuantitativeValue","unitCode":"E37","value":405},"url":"https://cdn.theatlantic.com/thumbor/Q0l6g-fb_AhCImhUqz3s3Mog96w=/0x0:2000x1125/720x405/media/img/mt/2023/12/what_is_life_/original.jpg"},{"@type":"ImageObject","width":{"@type":"QuantitativeValue","unitCode":"E37","value":1080},"height":{"@type":"QuantitativeValue","unitCode":"E37","value":1080},"url":"https://cdn.theatlantic.com/thumbor/2nd9Jv9zx1jRkxJWzly-1GtnwTE=/438x0:1563x1125/1080x1080/media/img/mt/2023/12/what_is_life_/original.jpg"},{"@type":"ImageObject","width":{"@type":"QuantitativeValue","unitCode":"E37","value":1200},"height":{"@type":"QuantitativeValue","unitCode":"E37","value":900},"url":"https://cdn.theatlantic.com/thumbor/onDv1TWzPr48xst4KFmlaZkSm2s=/249x0:1749x1125/1200x900/media/img/mt/2023/12/what_is_life_/original.jpg"},{"@type":"ImageObject","width":{"@type":"QuantitativeValue","unitCode":"E37","value":1600},"height":{"@type":"QuantitativeValue","unitCode":"E37","value":900},"url":"https://cdn.theatlantic.com/thumbor/Jg-QYPMiob8laaqFiGpxlmkdQ9s=/0x0:2000x1125/1600x900/media/img/mt/2023/12/what_is_life_/original.jpg"},{"@type":"ImageObject","width":{"@type":"QuantitativeValue","unitCode":"E37","value":960},"height":{"@type":"QuantitativeValue","unitCode":"E37","value":540},"url":"https://cdn.theatlantic.com/thumbor/75t4GJf5WHxA3zYoMWFQ32Jb8Yk=/0x0:2000x1125/960x540/media/img/mt/2023/12/what_is_life_/original.jpg"},{"@type":"ImageObject","width":{"@type":"QuantitativeValue","unitCode":"E37","value":540},"height":{"@type":"QuantitativeValue","unitCode":"E37","value":540},"url":"https://cdn.theatlantic.com/thumbor/WU05utB1gqqEV4uEWPSAcjmDPog=/438x0:1563x1125/540x540/media/img/mt/2023/12/what_is_life_/original.jpg"}],"author":[{"@type":"Person","name":"Jaime Green","sameAs":"https://www.theatlantic.com/author/jaime-green/"}],"articleSection":"Science"}</script><link rel="preload" as="image" href="https://cdn.theatlantic.com/thumbor/75t4GJf5WHxA3zYoMWFQ32Jb8Yk=/0x0:2000x1125/960x540/media/img/mt/2023/12/what_is_life_/original.jpg" imageSrcSet="https://cdn.theatlantic.com/thumbor/BObNhpaFMEy0usHGw7ytZuDaIe8=/0x0:2000x1125/750x422/media/img/mt/2023/12/what_is_life_/original.jpg 750w, https://cdn.theatlantic.com/thumbor/_JRdcb79qt4Ad4YZTWCKDKFsrVk=/0x0:2000x1125/828x466/media/img/mt/2023/12/what_is_life_/original.jpg 828w, https://cdn.theatlantic.com/thumbor/75t4GJf5WHxA3zYoMWFQ32Jb8Yk=/0x0:2000x1125/960x540/media/img/mt/2023/12/what_is_life_/original.jpg 960w, https://cdn.theatlantic.com/thumbor/ISqFpnaRM4gIbuua4EFP1lpm-i8=/0x0:2000x1125/976x549/media/img/mt/2023/12/what_is_life_/original.jpg 976w, https://cdn.theatlantic.com/thumbor/1gMWMUEgoXt_RjV2kkhtYvIHVQA=/0x0:2000x1125/1952x1098/media/img/mt/2023/12/what_is_life_/original.jpg 1952w" imageSizes="(min-width: 976px) 976px, 100vw"/><meta name="next-head-count" content="64"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/css/b95b4320f6718b0c.css" as="style"/><link rel="stylesheet" href="https://cdn.theatlantic.com/_next/static/css/b95b4320f6718b0c.css" data-n-g=""/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/css/3692c2fff3abdffb.css" as="style"/><link rel="stylesheet" href="https://cdn.theatlantic.com/_next/static/css/3692c2fff3abdffb.css" data-n-p=""/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/css/5097cfbd4c6bc22d.css" as="style"/><link rel="stylesheet" href="https://cdn.theatlantic.com/_next/static/css/5097cfbd4c6bc22d.css" data-n-p=""/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/css/1dce418bce276353.css" as="style"/><link rel="stylesheet" href="https://cdn.theatlantic.com/_next/static/css/1dce418bce276353.css" data-n-p=""/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/css/3e5015900a74444f.css" as="style"/><link rel="stylesheet" href="https://cdn.theatlantic.com/_next/static/css/3e5015900a74444f.css" data-n-p=""/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/css/0a33952225252f86.css" as="style"/><link rel="stylesheet" href="https://cdn.theatlantic.com/_next/static/css/0a33952225252f86.css" data-n-p=""/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/css/46047a12f0663966.css" as="style"/><link rel="stylesheet" href="https://cdn.theatlantic.com/_next/static/css/46047a12f0663966.css"/><noscript data-n-css=""></noscript><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/9587.e62a84643012a04f.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/5303-a81934d6e8e761ae.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/649.81412a92c899897e.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/webpack-2462136f7fddc57d.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/framework-ca706bf673a13738.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/main-7cf71189bb4b30b4.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/pages/_app-ff1d27643a500c40.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/6729-7978443139836095.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/5303-a81934d6e8e761ae.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/9843-3905ec2636af2c3c.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/899-30da5ef51c1b6fdb.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/2912-ebf029ed4116b01f.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/4747-71d47472f5c4beea.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/6392-1397c4f8500d73b6.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/4947-02b1b9c56798b167.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/3297-031e2fc5be155f31.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/365-e835216503d223da.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/1124-b1cf3a9d4ae92dcb.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/9310-d0d5baafd7a7f3b8.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/5169-3adfae2cce1eb773.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/6346-ef3edb895c92109b.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/663-0fc7e1b7a52e2587.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/2544-aaa838d354b1cbbb.js" as="script"/><link rel="preload" href="https://cdn.theatlantic.com/_next/static/chunks/pages/%5Bchannel%5D/archive/%5Byear%5D/%5Bmonth%5D/%5Bslug%5D/%5Bid%5D-0fee4688858b18b9.js" as="script"/></head><body><div id="__next"><div data-category="story page" data-event-surface="article"><div></div><nav class="Nav_root__HcZek" aria-labelledby="site-navigation" data-category="Site Nav" data-event-module="site nav" id="main-navigation"><div class="Nav_mainNav__iPsWc"><a href="#main-content" class="Nav_skipLink__P4Y5R">Skip to content</a><h2 id="site-navigation" class="Nav_visuallyHide__Lzzui">Site Navigation</h2><div class="Nav_flexContainer__9iJ4H"><ul class="Nav_leftContainer__Xs54R"><li class="Nav_navListItem__l2afO Nav_visuallyHideOnMobile__N9bs2"><a href="/" class="Nav_navLink__34Bol"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 87.83 134" class="Nav_bigA__c1aIb"><title>The Atlantic</title><path d="M24.48 95.13c-.56 0-.74-.37-.74-.93l13.08-55.88c.19-.94.93-.94 1.12 0L50.09 94.2c0 .56-.19.93-.75.93zM48.22.19a22.54 22.54 0 01-7.66 5.05c-.75.19-.94.37-1.13 1.12l-26.72 112.5c-2 9-4.67 10.66-11.77 11.22a.88.88 0 00-.94.93v2.06a.88.88 0 00.92.93h25.6a.88.88 0 00.93-.93V131a.88.88 0 00-.93-.93c-9.53 0-10.47-2.81-8.6-10.66l4.49-19.25a1.18 1.18 0 011.12-.93h26.74a1.19 1.19 0 011.13.93l5 23.18c1.12 5-.75 6.17-7.1 6.73a.88.88 0 00-.93.93v2.06a.88.88 0 00.93.93h37.62a.88.88 0 00.94-.93V131a.88.88 0 00-.94-.93c-5.79-.56-8.22-1.5-9.34-6.73L49.34.57c-.19-.56-.75-.75-1.12-.38"></path></svg></a></li><li class="Nav_navListItem__l2afO Nav_hamburgerLi__gP6Dn"><button class="NavHamburgerButton_root__OgJkB" aria-expanded="false" aria-controls="expanded-nav" aria-label="Open Main Menu" data-action="Open Menu"><div class="NavHamburgerButton_burger__jIWmI"><div class="NavHamburgerButton_box__J5rDn"><div class="NavHamburgerButton_inner__dKlIy"></div></div></div></button><div class="Nav_expandedNav__o5Zj_"><div hidden="" class="ExpandedNav_root__r3hKE" id="expanded-nav"><div class="ExpandedNav_mobileHeader__QEenD" data-event-element="mobile links"><button class="ExpandedNav_searchButton__85mWm" aria-label="Search The Atlantic" data-action="open search"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16" class="ExpandedNav_searchIcon__2EngD"><path d="M15.85 15.15l-5.27-5.28a6 6 0 10-.71.71l5.28 5.27a.48.48 0 00.7 0 .48.48 0 000-.7zM1 6a5 5 0 115 5 5 5 0 01-5-5z"></path></svg></button><div><a class="ExpandedNav_mostPopular__EbSyn" href="/most-popular/" data-action="expanded">Popular</a><a class="ExpandedNav_latest__zSrBe" href="/latest/" data-action="expanded">Latest</a><a class="ExpandedNav_newsletters__W83ni" href="/newsletters/" data-action="expanded">Newsletters</a></div></div><div class="ExpandedNav_container__sDhOz"><div class="ExpandedNav_sections__oGeXo" data-event-element="sections"><h2 class="ExpandedNav_title__C8QcN ExpandedNav_sectionTitle___xWBI">Sections</h2><ul class="ExpandedNav_sectionUl__mLUY1"><li class="ExpandedNav_sectionLi__tZz7K"><a href="/politics/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Politics</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/ideas/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Ideas</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="https://www.theatlantic.com/category/fiction/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Fiction</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/technology/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Technology</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/science/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Science</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="https://www.theatlantic.com/photo/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Photo</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/business/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Business</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/culture/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Culture</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/projects/planet/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Planet</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/international/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Global</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/books/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Books</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/audio/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Audio</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/health/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Health</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/education/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Education</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/projects/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Projects</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="https://www.theatlantic.com/category/features/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Features</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/family/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Family</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/events/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Events</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="https://www.theatlantic.com/category/washington-week-atlantic/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Washington Week</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="https://www.theatlantic.com/progress/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Progress</a></li><li class="ExpandedNav_sectionLi__tZz7K"><a href="/newsletters/" data-action="expanded" class="ExpandedNav_sectionLink__3iXo9">Newsletters</a></li></ul></div><div class="ExpandedNav_moreLinks__G4VPb" data-event-element="more links"><ul class="ExpandedNav_moreLinksList__u0bVY"><li class="ExpandedNav_moreLinksListItem__UrTkv"><a href="/archive/" class="ExpandedNav_moreLinksItem__JhFzM" data-action="archive"><img alt="" loading="lazy" class="Image_root__XxsOp Image_lazy__hYWHV ExpandedNav_moreLinksImg__IY3fl" src="https://cdn.theatlantic.com/_next/static/images/nav-archive-promo-5541b02ae92f1a9276249e1c6c2534ee.png" width="80" height="80"/><span>Explore The Atlantic Archive</span></a></li><li class="ExpandedNav_moreLinksListItem__UrTkv"><a href="/free-daily-crossword-puzzle/" class="ExpandedNav_moreLinksItem__JhFzM" data-action="crossword"><svg width="80" height="80" viewBox="0 0 64 64" fill="none" xmlns="http://www.w3.org/2000/svg" class="ExpandedNav_moreLinksImg__IY3fl"><g clip-path="url(#crossword-promo_svg__clip0_1939_66324)"><path fill="#E7131A" d="M0 0h64v64H0z"></path><path d="M37.988 26.531H26.516v11.474h11.472V26.53zM37.988 38.805H26.516V50.28h11.472V38.805zM25.715 26.531H14.243v11.474h11.472V26.53zM50.26 26.531H38.789v11.474h11.473V26.53zM36.469 16.842c.096.183.156.39.156.612a1.326 1.326 0 11-1.326-1.327c.197 0 .384.047.552.124.167-.464.303-1.137.338-1.993h-5.287c-.039.968-.217 1.908-.527 2.584.096.183.156.39.156.612a1.326 1.326 0 11-1.327-1.327c.198 0 .384.047.552.124.167-.464.303-1.137.339-1.993h-3.58v11.474h11.472V14.258h-.992c-.038.968-.216 1.908-.526 2.584z" fill="#fff"></path><path d="M47.487 17.853a.4.4 0 010-.8c.135 0 .36-.27.552-.803a1.313 1.313 0 00-.552-.124 1.326 1.326 0 101.326 1.327c0-.222-.06-.428-.156-.612-.282.615-.674 1.012-1.17 1.012zM41.393 17.853a.4.4 0 010-.8c.135 0 .36-.27.552-.803a1.313 1.313 0 00-.552-.124 1.326 1.326 0 101.326 1.327c0-.222-.06-.428-.156-.612-.282.615-.673 1.012-1.17 1.012zM35.298 17.853a.4.4 0 010-.8c.135 0 .36-.27.552-.803a1.313 1.313 0 00-.552-.124 1.326 1.326 0 101.326 1.327c0-.222-.06-.428-.156-.612-.282.615-.673 1.012-1.17 1.012zM29.204 17.853a.4.4 0 010-.8c.136 0 .36-.27.552-.803a1.313 1.313 0 00-.552-.124 1.326 1.326 0 101.327 1.327c0-.222-.06-.428-.156-.612-.282.615-.673 1.012-1.17 1.012zM23.11 17.853a.4.4 0 010-.8c.135 0 .36-.27.552-.803a1.313 1.313 0 00-.552-.124 1.326 1.326 0 101.326 1.327c0-.222-.06-.428-.156-.612-.282.615-.673 1.012-1.17 1.012zM17.016 17.853a.4.4 0 010-.8c.135 0 .36-.27.552-.803a1.313 1.313 0 00-.552-.124 1.326 1.326 0 101.326 1.327c0-.222-.06-.428-.156-.612-.282.615-.672 1.012-1.17 1.012z" fill="#E7131A"></path><path d="M50.66 13.458h-1.476c-.072-1.85-.652-3.605-1.698-3.605-1.045 0-1.624 1.753-1.697 3.605h-2.7c-.071-1.85-.651-3.605-1.698-3.605-1.045 0-1.624 1.753-1.697 3.605h-2.7c-.072-1.85-.652-3.605-1.698-3.605-1.045 0-1.624 1.753-1.697 3.605H30.9c-.072-1.85-.652-3.605-1.698-3.605-1.045 0-1.624 1.753-1.697 3.605h-2.697c-.072-1.85-.652-3.605-1.698-3.605-1.045 0-1.624 1.753-1.697 3.605h-2.7c-.071-1.85-.651-3.605-1.698-3.605-1.045 0-1.624 1.753-1.697 3.605h-1.476a.4.4 0 00-.4.4V50.68c0 .22.18.4.4.4H50.66a.4.4 0 00.4-.4V13.858c0-.221-.178-.4-.4-.4zm-20.565.8c-.035.855-.171 1.528-.338 1.992-.192.532-.417.803-.552.803a.4.4 0 000 .8c.497 0 .888-.398 1.17-1.012.31-.676.488-1.616.527-2.583h5.288c-.036.855-.172 1.528-.339 1.992-.192.532-.417.803-.552.803a.4.4 0 000 .8c.498 0 .888-.398 1.17-1.012.311-.676.489-1.616.528-2.583h.992V25.73H26.515V14.258h3.58zm20.166 23.747H38.788V26.53h11.473v11.474zM14.243 26.53h11.472v11.474H14.243V26.53zm34.57-9.078a1.326 1.326 0 11-1.327-1.327c.198 0 .384.047.552.124-.192.532-.416.803-.552.803a.4.4 0 000 .8c.498 0 .888-.398 1.17-1.012.097.184.157.39.157.612zm-7.42.4c.497 0 .888-.398 1.17-1.012.096.183.156.39.156.612a1.326 1.326 0 11-1.326-1.327c.197 0 .384.047.552.124-.192.532-.417.803-.552.803a.4.4 0 000 .8zm-3.405 20.152H26.515V26.53h11.473v11.474zM24.436 17.453a1.326 1.326 0 11-1.326-1.327c.197 0 .384.047.552.124-.192.532-.417.803-.552.803a.4.4 0 000 .8c.497 0 .888-.398 1.17-1.012.097.184.156.39.156.612zm-6.094 0a1.326 1.326 0 11-1.326-1.327c.198 0 .384.047.552.124-.192.532-.417.803-.552.803a.4.4 0 000 .8c.498 0 .888-.398 1.17-1.012.097.184.156.39.156.612zm8.173 21.352h11.473V50.28H26.515V38.805zm20.971-28.152c.253 0 .817.96.892 2.805h-1.782c.075-1.844.638-2.805.89-2.805zm-6.093 0c.253 0 .817.96.891 2.805h-1.782c.076-1.844.638-2.805.89-2.805zm-6.095 0c.253 0 .817.96.892 2.805h-1.782c.075-1.844.638-2.805.89-2.805zm-6.094 0c.253 0 .817.96.891 2.805h-1.781c.075-1.844.637-2.805.89-2.805zm-6.094 0c.252 0 .816.96.89 2.805h-1.78c.074-1.844.637-2.805.89-2.805zm-6.094 0c.253 0 .817.96.891 2.805h-1.781c.075-1.844.637-2.805.89-2.805z" fill="#000"></path></g><defs><clipPath id="crossword-promo_svg__clip0_1939_66324"><path fill="#fff" d="M0 0h64v64H0z"></path></clipPath></defs></svg><span>Play The Atlantic crossword</span></a></li><li class="ExpandedNav_moreLinksListItem__UrTkv"><a href="/audio/" class="ExpandedNav_moreLinksItem__JhFzM" data-action="audio"><svg width="80" height="80" viewBox="0 0 64 64" fill="none" xmlns="http://www.w3.org/2000/svg" class="ExpandedNav_moreLinksImg__IY3fl"><path fill="#FAF4EB" d="M0 0h63.998v64H0z"></path><path d="M25.267 31.27h-1.171v12.138h1.17a.392.392 0 00.393-.392V31.662a.392.392 0 00-.392-.393v.002zM38.34 31.662v11.354c0 .217.175.392.392.392h1.171V31.271h-1.17a.392.392 0 00-.393.392v-.002z" fill="#000"></path><path d="M44.605 33.479c.106-.69.163-1.398.163-2.12 0-7.343-5.718-13.296-12.77-13.296-7.05 0-12.768 5.953-12.768 13.296 0 .722.057 1.429.163 2.12l-1.413.58v6.56l2.033.834a3.194 3.194 0 001.586 1.65c.411.193.869.305 1.353.305h.34V31.271h-.34c-.174 0-.345.017-.511.044a3.14 3.14 0 00-1.236.48c-.005-.145-.011-.289-.011-.434 0-6.25 4.847-11.334 10.805-11.334 5.958 0 10.805 5.085 10.805 11.334 0 .145-.005.29-.01.433a3.163 3.163 0 00-1.748-.523h-.34v12.137h.34a3.197 3.197 0 002.939-1.953l2.033-.835v-6.56l-1.413-.58v-.001zM35.71 49.806a.498.498 0 100 .997.498.498 0 000-.997zM30.235 50.8a.498.498 0 100-.996.498.498 0 000 .997zM28.059 48.218a.498.498 0 100 .997.498.498 0 000-.997zM32.104 50.072a.498.498 0 100-.997.498.498 0 000 .997zM33.105 47.731a.498.498 0 100 .997.498.498 0 000-.997zM29.675 48.09a.498.498 0 10.996 0 .498.498 0 00-.996 0zM35.71 48.156a.498.498 0 10-.997 0 .498.498 0 00.997 0zM37.508 49.085a.498.498 0 100 .996.498.498 0 000-.996zM39 47.336a.498.498 0 100 .996.498.498 0 000-.996zM39.159 45.754a.498.498 0 100 .996.498.498 0 000-.996zM40.74 46.07a.498.498 0 100 .997.498.498 0 000-.997zM40.266 44.33a.498.498 0 100 .997.498.498 0 000-.997zM34.47 49.983a.498.498 0 10-.996 0 .498.498 0 00.997 0zM27.746 51.075a.498.498 0 100-.997.498.498 0 000 .997zM29.736 51.668a.498.498 0 100 .996.498.498 0 000-.996zM32.375 52.8a.498.498 0 100-.997.498.498 0 000 .997zM48.894 42.2a.498.498 0 100 .997.498.498 0 000-.997zM50.794 25.623a.497.497 0 10.7.082.497.497 0 00-.7-.082zM50.32 27.679a.497.497 0 10.7.082.497.497 0 00-.7-.082zM48.52 25.229a.497.497 0 10.78-.614.497.497 0 00-.78.614zM48.809 20.633a.498.498 0 10.616.781.498.498 0 00-.616-.781zM52.468 24.48a.497.497 0 10.78-.614.497.497 0 00-.78.615zM54.84 24.769a.498.498 0 10.617.781.498.498 0 00-.616-.781zM55.338 27.141a.497.497 0 10.782-.617.497.497 0 10-.782.617zM53.817 27.018a.497.497 0 10-.781.614.497.497 0 00.781-.614zM57.145 29.216a.498.498 0 10-.616-.781.498.498 0 00.616.781zM55.064 23.779a.498.498 0 10-.617-.782.498.498 0 00.617.782zM40.054 13.142a.498.498 0 10-.617-.781.498.498 0 00.617.781zM53.735 21.578a.498.498 0 10-.616-.78.498.498 0 00.616.78zM55.85 31.981a.497.497 0 10-.78.614.497.497 0 00.78-.614zM54.84 33.58a.498.498 0 10.617.781.498.498 0 00-.616-.78zM56.316 35.18a.497.497 0 10.617.784.497.497 0 00-.617-.783zM55.966 37.762a.498.498 0 10.616.781.498.498 0 00-.616-.781zM56.498 33.18a.498.498 0 10.617.781.498.498 0 00-.617-.781zM53.13 41.909a.498.498 0 10.617.78.498.498 0 00-.617-.78zM42.078 49.183a.498.498 0 10.617.781.498.498 0 00-.617-.781zM40.255 50.41a.498.498 0 10.616.782.498.498 0 00-.616-.782zM36.42 51.49a.498.498 0 10.618.782.498.498 0 00-.617-.782zM33.851 51.728a.498.498 0 10.617.78.498.498 0 00-.617-.78zM38.312 50.842a.498.498 0 10.616.781.498.498 0 00-.616-.78zM50.653 43.918a.498.498 0 10-.617-.78.498.498 0 00.617.78zM50.393 44.936a.498.498 0 10.616.782.498.498 0 00-.616-.782zM57.489 31.298a.497.497 0 10-.782.617.497.497 0 10.782-.617zM51.652 19.689a.497.497 0 10-.617-.784.497.497 0 00.617.784zM51.154 21.688a.498.498 0 10-.616-.782.498.498 0 00.616.782zM48.69 19.641a.497.497 0 10.781-.614.497.497 0 00-.781.614zM48.465 17.63a.498.498 0 10-.617-.782.498.498 0 00.617.781zM46.498 16.596a.5.5 0 00.554-.435.5.5 0 00-.99-.118.5.5 0 00.436.553zM46.244 18.243a.5.5 0 00.435.554.5.5 0 00.554-.436.5.5 0 00-.435-.553.5.5 0 00-.554.435zM45.325 15.307a.5.5 0 00.554-.435.5.5 0 00-.989-.118.5.5 0 00.435.553zM42.096 13.917a.5.5 0 00.554-.435.5.5 0 00-.435-.553.5.5 0 00-.554.434.5.5 0 00.435.554zM49.606 18.61a.5.5 0 00.554-.435.5.5 0 00-.989-.119.5.5 0 00.435.554zM45.478 17.63a.498.498 0 10-.616-.782.498.498 0 00.616.781zM43.392 17.311a.497.497 0 10-.782.617.497.497 0 10.782-.617zM54.34 36.596a.498.498 0 10.781-.618.498.498 0 00-.782.618zM53.384 36.69a.498.498 0 10-.617-.782.498.498 0 00.617.782zM51.95 37.01a.497.497 0 10-.7-.082c.172.217.483.253.7.083zM53.176 31.27a.498.498 0 10.616.782.498.498 0 00-.616-.781zM54.792 30.407a.498.498 0 10.616.782.498.498 0 00-.616-.782zM52.13 32.454a.498.498 0 10.617.781.498.498 0 00-.617-.781zM53.656 35.098a.498.498 0 10-.616-.781.498.498 0 00.616.781zM53.384 30.417a.498.498 0 10-.617-.782.498.498 0 00.617.782zM54.654 28.826a.498.498 0 10-.616-.782.498.498 0 00.616.782zM51.187 31.662a.497.497 0 10-.781.616.497.497 0 10.781-.616zM48.774 26.268a.497.497 0 10.7.082.497.497 0 00-.7-.082zM49.475 29.322a.498.498 0 10-.617-.781.498.498 0 00.617.781zM49.974 33.465a.498.498 0 10-.617-.782.498.498 0 00.617.782zM50.242 35.438a.498.498 0 10-.616-.78.498.498 0 00.616.78zM48.915 34.097a.497.497 0 10-.662.742.497.497 0 00.662-.742zM47.957 35.54a.497.497 0 10-.662.743.497.497 0 10.662-.743zM47.582 37.525a.497.497 0 10-.662.743.497.497 0 10.662-.743zM51.792 34.599a.498.498 0 10-.617-.782.498.498 0 00.617.782zM49.54 29.909a.498.498 0 10.617.781.498.498 0 00-.617-.781zM52.032 28.215a.498.498 0 10.617.78.498.498 0 00-.617-.78zM53.158 26.426a.497.497 0 10-.7-.082c.171.217.483.253.7.082zM48.578 32.179a.498.498 0 10-.617-.782.498.498 0 00.617.782zM50.89 30.403a.5.5 0 00.988.118.5.5 0 00-.989-.118zM46.624 25.265a.498.498 0 10.617.78.498.498 0 00-.617-.78z" fill="#000"></path><path d="M45.827 31.83a.497.497 0 10.7.082.497.497 0 00-.7-.083zM47.58 33.16a.497.497 0 10-.781.613.497.497 0 00.781-.614zM47.74 27.738a.498.498 0 10-.616-.782.498.498 0 00.616.782zM47.95 30.243a.5.5 0 00-.99-.119.5.5 0 00.99.119zM46.367 30.243a.5.5 0 00-.99-.119.5.5 0 00.99.119zM46.683 28.345a.5.5 0 00-.99-.119.5.5 0 00.99.119zM45.734 26.921a.5.5 0 00-.99-.118.5.5 0 00.99.118zM51.545 23.233a.497.497 0 10.781-.614.497.497 0 00-.781.614zM6.538 28.26a.499.499 0 10.51-.853.499.499 0 00-.51.852zM7.67 26.127a.499.499 0 10.51-.854.499.499 0 00-.51.854zM22.566 14.925a.499.499 0 10.51-.853.499.499 0 00-.51.853zM14.93 46.545a.499.499 0 10-.51.854.499.499 0 00.51-.854zM14.43 45.648a.499.499 0 10-.856-.512.499.499 0 00.856.512zM8.545 24.343a.499.499 0 10.51-.853.499.499 0 00-.51.853zM9.538 22.678a.5.5 0 10.51-.853.5.5 0 00-.51.853zM8.556 29.822a.499.499 0 10-.856-.512.499.499 0 00.856.512zM17.15 16.267a.498.498 0 10-.616-.781.498.498 0 00.616.781zM6.896 33.144a.498.498 0 10-.616-.782.498.498 0 00.616.782zM9.125 33.325a.498.498 0 10-.616-.781.498.498 0 00.616.781zM7.207 34.31a.498.498 0 10-.782.617.498.498 0 00.782-.618zM15.916 46.436a.498.498 0 100-.997.498.498 0 000 .997zM16.595 48.48a.498.498 0 100-.996.498.498 0 000 .997zM18.442 49.436a.498.498 0 100-.997.498.498 0 000 .997zM13.869 18.485a.498.498 0 100-.997.498.498 0 000 .997zM18.393 15.409a.498.498 0 100-.997.498.498 0 000 .997zM21.04 14.363a.497.497 0 10-.701-.704.497.497 0 00.702.704zM25.524 12.75a.497.497 0 10-.702-.704.497.497 0 00.702.704zM28.182 12.285a.497.497 0 10-.702-.704.497.497 0 00.702.704zM18.673 47.005a.498.498 0 10-.997 0 .498.498 0 00.997 0zM12.707 42.075a.498.498 0 10-.001.997.498.498 0 000-.997zM12.512 39.8a.498.498 0 10-.07-.993.498.498 0 00.07.994zM10.954 40.65a.498.498 0 100-.997.498.498 0 000 .997zM11.492 41.112a.498.498 0 100 .996.498.498 0 000-.996zM9.543 41.143a.498.498 0 100 .997.498.498 0 000-.997zM14.316 40.844a.498.498 0 10-.996 0 .498.498 0 00.996 0zM13.704 38.478a.498.498 0 100-.996.498.498 0 000 .996zM15.03 36.2a.498.498 0 10-.997 0 .498.498 0 00.997 0zM14.652 33.933a.498.498 0 100-.997.498.498 0 000 .997zM11.635 35.752a.498.498 0 100-.997.498.498 0 000 .997zM12.41 33.66a.498.498 0 100-.996.498.498 0 000 .997zM8.618 37.754a.498.498 0 10-.996 0 .498.498 0 00.996 0zM8.329 39.347a.498.498 0 100 .996.498.498 0 000-.996zM11.083 38.577a.498.498 0 10-.997 0 .498.498 0 00.997 0zM10.124 37.434a.498.498 0 100-.996.498.498 0 000 .996zM7.317 36.843a.498.498 0 100-.997.498.498 0 000 .997zM12.525 37.447a.497.497 0 10-.702-.704.497.497 0 00.702.704zM12.242 29.982a.498.498 0 100 .996.498.498 0 000-.996zM9.54 35.253a.498.498 0 10-.997 0 .498.498 0 00.997 0zM11.192 33.647a.498.498 0 10-.996 0 .498.498 0 00.996 0zM15.171 28.82a.498.498 0 100-.997.498.498 0 000 .996zM17.296 28.661a.498.498 0 100-.997.498.498 0 000 .997zM16.7 29.59a.498.498 0 10-.997 0 .498.498 0 00.996 0zM18.282 30.064a.498.498 0 10-.996 0 .498.498 0 00.996 0zM19.386 21.03a.498.498 0 100 .996.498.498 0 000-.996zM17.714 32.372a.498.498 0 100-.997.498.498 0 000 .997zM16.665 33.488a.498.498 0 100-.996.498.498 0 000 .996zM16.225 35.07a.498.498 0 100-.997.498.498 0 000 .997zM16.665 36.63a.498.498 0 100-.997.498.498 0 000 .996zM11.908 25.748a.498.498 0 100-.997.498.498 0 000 .997zM15.123 21.001a.498.498 0 100 .997.498.498 0 000-.997zM15.047 20.157a.498.498 0 100-.997.498.498 0 000 .997zM16.58 18.614a.498.498 0 100-.996.498.498 0 000 .997zM15.621 17.62a.498.498 0 10.001-.997.498.498 0 000 .997zM13.37 20.775a.498.498 0 100-.997.498.498 0 000 .997zM11.91 20.248a.498.498 0 10.001-.996.498.498 0 000 .996zM11.35 21.843a.498.498 0 100-.997.498.498 0 000 .997zM14.343 26.426a.498.498 0 100-.996.498.498 0 000 .996zM13.206 25.16a.498.498 0 100-.997.498.498 0 000 .996zM11.76 27.034a.498.498 0 10.997 0 .498.498 0 00-.996 0zM9.499 25.113a.498.498 0 10.997 0 .498.498 0 00-.997 0zM13.357 22.923a.498.498 0 10-.07-.994.498.498 0 00.07.994zM11.248 23.943a.498.498 0 100-.997.498.498 0 000 .997zM9.829 30.444a.498.498 0 100-.997.498.498 0 000 .997zM6.477 30.706a.498.498 0 100-.996.498.498 0 000 .996zM40.136 14a.5.5 0 10.857.513.5.5 0 00-.857-.512zM39.218 15.744a.499.499 0 10.51-.853.499.499 0 00-.51.853zM39.038 17.507a.499.499 0 10.51-.853.499.499 0 00-.51.853zM37.456 17.982a.499.499 0 10.51-.853.499.499 0 00-.51.853zM41.253 15.885a.499.499 0 10.51-.854.499.499 0 00-.51.854zM41.353 17.536a.499.499 0 10-.857-.512.499.499 0 00.857.512zM8.566 31.717a.498.498 0 100-.997.498.498 0 000 .997zM9.944 31.593a.498.498 0 10.997 0 .498.498 0 00-.997 0zM11.185 29.07a.498.498 0 10.996 0 .498.498 0 00-.996 0zM8.995 27.706a.498.498 0 100-.997.498.498 0 000 .997zM10.51 28.41a.498.498 0 100-.997.498.498 0 000 .997zM13.48 29.227a.498.498 0 10.001-.996.498.498 0 000 .996zM15.417 32.092a.498.498 0 100-.997.498.498 0 000 .997zM13.704 32.215a.498.498 0 100-.997.498.498 0 000 .997zM14.501 30.37a.498.498 0 100-.997.498.498 0 000 .996zM44.77 48.378a.498.498 0 00-.518.85.498.498 0 00.518-.85zM44.012 45.958a.499.499 0 00.517-.85.498.498 0 00-.517.85zM42.917 46.809a.498.498 0 10-.851-.517.498.498 0 00.851.517zM46.904 44.45a.498.498 0 10.516-.849.498.498 0 00-.517.85zM46.057 44.471a.498.498 0 10-.852-.516.498.498 0 00.852.516zM44.79 43.206a.498.498 0 10-.851-.517.498.498 0 00.851.517zM46.407 46.65a.498.498 0 10-.852-.516.498.498 0 00.852.517zM44.657 47.563a.498.498 0 10-.852-.516.498.498 0 00.852.516zM46.963 47.375a.498.498 0 00-.517.85.498.498 0 00.517-.85zM39.595 48.876a.498.498 0 00-.518.85.498.498 0 00.518-.85zM41.32 47.967a.498.498 0 00-.517.849.498.498 0 00.517-.85zM36.547 47.83a.498.498 0 10.851.517.498.498 0 00-.851-.516zM33.264 45.833a.498.498 0 100 .997.498.498 0 000-.997zM35.394 45.468a.498.498 0 10-.997 0 .498.498 0 00.997 0zM36.23 46.249a.498.498 0 10.852.517.498.498 0 00-.852-.517zM37.813 44.351a.498.498 0 10.852.517.498.498 0 00-.852-.517zM47.713 45.044a.498.498 0 00-.517.85.498.498 0 00.517-.85zM49.34 44.473a.499.499 0 00-.518.85.498.498 0 00.518-.85zM48.94 46.502a.498.498 0 10-.516.849.498.498 0 00.516-.849zM50.182 41.493a.498.498 0 10.347.933.498.498 0 00-.347-.933zM49.576 40.558a.498.498 0 10-.934.348.498.498 0 00.934-.348zM46.79 42.667a.498.498 0 10-.346-.933.498.498 0 00.347.933zM47.899 39.962a.498.498 0 10-.933.348.498.498 0 00.933-.348zM51.826 41.47a.497.497 0 10-.346-.932.497.497 0 00.346.933zM49.417 38.224a.498.498 0 10-.933.347.498.498 0 00.933-.347zM50.899 38.714a.498.498 0 10-.933.348.498.498 0 00.933-.348zM49.917 36.489a.498.498 0 10-.934.348.498.498 0 00.934-.348zM51.808 37.923a.498.498 0 10.347.933.498.498 0 00-.347-.933zM25.17 15.247a.498.498 0 100-.996.498.498 0 000 .996zM25.17 16.549a.498.498 0 10.998 0 .498.498 0 00-.997 0zM41.896 19.856a.498.498 0 10-.996 0 .498.498 0 00.996 0zM43.262 18.78a.498.498 0 100 .996.498.498 0 000-.997zM52.1 43.393a.498.498 0 10-.414.906.498.498 0 00.414-.906zM54.618 40.212a.496.496 0 00-.494.501.496.496 0 00.502.494.496.496 0 00.494-.502.496.496 0 00-.502-.493zM54.758 37.561a.496.496 0 00-.493.501.496.496 0 00.501.494.496.496 0 00.494-.502.496.496 0 00-.502-.493zM53.63 39.454a.496.496 0 00-.502-.493.497.497 0 10.502.494zM15.092 23.477a.498.498 0 10.347.932.498.498 0 00-.347-.932zM16.58 20.122a.498.498 0 10.996 0 .498.498 0 00-.997 0zM15.584 26.195a.498.498 0 10.997 0 .498.498 0 00-.997 0zM18.37 27.473a.498.498 0 100-.996.498.498 0 000 .996zM17.454 22.898a.498.498 0 100 .996.498.498 0 000-.996zM17.454 24.796a.498.498 0 100 .996.498.498 0 000-.996zM19.924 19.307a.498.498 0 100 .997.498.498 0 000-.997zM18.988 23.441a.498.498 0 10-.07-.994.498.498 0 00.07.994zM16.878 21.428a.498.498 0 100 .997.498.498 0 000-.997zM30.591 13.057a.497.497 0 10.346.932.497.497 0 00-.346-.932zM30.323 15.714a.498.498 0 10-.346-.933.498.498 0 00.346.933zM32.607 12.294a.498.498 0 100-.996.498.498 0 000 .996zM27.075 16.225a.498.498 0 10.933-.348.498.498 0 00-.933.348zM32.284 16.261a.498.498 0 10-.347-.933.498.498 0 00.347.933zM36.416 13.586a.499.499 0 10-.71-.699.499.499 0 00.71.7zM37.33 12.522a.499.499 0 10-.712-.7.499.499 0 00.712.7zM35.19 12.328a.499.499 0 10-.71-.7.499.499 0 00.71.7zM35.425 16.1a.499.499 0 10.697-.709.499.499 0 00-.697.709zM37.708 15.619a.499.499 0 10-.712-.7.499.499 0 00.712.7zM37.516 14.336a.499.499 0 10.697-.708.499.499 0 00-.697.708zM32.283 13.41a.499.499 0 10.711.7.499.499 0 00-.711-.7zM43.28 15.606a.499.499 0 10.71.7.499.499 0 00-.71-.7zM43.688 14.83a.499.499 0 10-.711-.7.499.499 0 00.71.7zM34.645 14.847a.499.499 0 10-.711-.699.499.499 0 00.711.7zM22.876 13.54a.499.499 0 10.51-.854.499.499 0 00-.51.855zM26.427 13.996a.499.499 0 10.51-.853.499.499 0 00-.51.853zM28.11 13.745a.499.499 0 10.857.511.499.499 0 00-.856-.511zM30.125 12.127a.499.499 0 10.51-.853.499.499 0 00-.51.853zM19.727 46.404a.498.498 0 10.139-.688.497.497 0 00-.14.69v-.002zM21.264 16.28a.498.498 0 10.584-.807.498.498 0 00-.584.807zM23.283 17.712a.497.497 0 10-.806-.584.497.497 0 00.806.584zM21.883 20.704a.497.497 0 10-.806-.584.497.497 0 00.806.584zM22.367 18.346a.498.498 0 10-.584.806.498.498 0 00.584-.806zM23.632 19.295a.498.498 0 10-.583.806.498.498 0 00.583-.806zM21.258 21.825a.498.498 0 10-.583.807.498.498 0 00.583-.807zM19.194 44.97a.498.498 0 10-.984-.156.498.498 0 00.984.155zM17.093 44.084a.498.498 0 10-.156.983.498.498 0 00.156-.983zM18.877 43.184a.498.498 0 10.156-.983.498.498 0 00-.156.983zM19.72 47.355a.498.498 0 10-.156.983.498.498 0 00.156-.983zM13.898 44.147a.498.498 0 10.156-.983.498.498 0 00-.156.983zM11.166 43.092a.498.498 0 10-.156.983.498.498 0 00.156-.983zM12.732 44.693a.497.497 0 10-.643.758.497.497 0 00.643-.758zM25.903 49.082a.498.498 0 10-.156.983.498.498 0 00.156-.983zM25.294 48.085a.497.497 0 10.983.156.497.497 0 00-.983-.156zM24.187 46.662a.498.498 0 10.983.155.498.498 0 00-.983-.155zM25.294 45.397a.498.498 0 10.983.155.498.498 0 00-.983-.155zM26.56 43.657a.498.498 0 10.983.155.498.498 0 00-.983-.155zM26.718 47.136a.498.498 0 10.983.156.498.498 0 00-.983-.156zM27.826 45.397a.498.498 0 10.983.155.498.498 0 00-.983-.155zM29.567 46.187a.497.497 0 10.982.156.497.497 0 00-.982-.156zM31.308 45.238a.498.498 0 10.983.156.498.498 0 00-.983-.156zM31.308 47.294a.498.498 0 10.983.156.498.498 0 00-.983-.156zM26.826 51.355a.498.498 0 10-.156.983.498.498 0 00.156-.983zM30.548 44.587a.498.498 0 10-.997 0 .498.498 0 00.997 0zM29.282 42.847a.498.498 0 10-.996 0 .498.498 0 00.996 0zM29.575 38.505a.498.498 0 100-.996.498.498 0 000 .996zM31.662 35.834a.498.498 0 10-.997 0 .498.498 0 00.997 0zM30.306 40.375a.498.498 0 100-.997.498.498 0 000 .997zM32.148 40.878a.498.498 0 10-.996 0 .498.498 0 00.996 0zM31.79 37.449a.498.498 0 100 .996.498.498 0 000-.996zM31.722 43.48a.498.498 0 100-.997.498.498 0 000 .997zM30.529 42.559a.498.498 0 100-.996.498.498 0 000 .996zM29.302 36.017a.498.498 0 100-.996.498.498 0 000 .996zM28.369 37.669a.498.498 0 10-.997 0 .498.498 0 00.997 0zM28.526 40.805a.498.498 0 100-.997.498.498 0 000 .997zM26.943 39.856a.498.498 0 100-.997.498.498 0 000 .997zM27.832 41.465a.497.497 0 10-.782.616.497.497 0 10.782-.617zM34.047 41.036a.498.498 0 10-.997 0 .498.498 0 00.997 0zM34.413 43.321a.498.498 0 100-.996.498.498 0 000 .996zM33.305 44.903a.498.498 0 100-.997.498.498 0 000 .997zM36.224 34.494a.498.498 0 10-.156.983.498.498 0 00.156-.983zM32.743 34.494a.498.498 0 10-.156.983.498.498 0 00.156-.983zM34.484 35.601a.498.498 0 10-.156.984.498.498 0 00.156-.984zM33.692 37.341a.498.498 0 10-.156.984.498.498 0 00.156-.984zM34.642 39.081a.498.498 0 10-.156.983.498.498 0 00.156-.983zM32.585 39.081a.498.498 0 10-.156.983.498.498 0 00.156-.983zM27.256 36.342a.498.498 0 10-.983-.156.498.498 0 00.983.156zM27.732 34.76a.498.498 0 10-.983-.156.498.498 0 00.983.156zM24.091 50.586a.497.497 0 10.2.974.497.497 0 00-.2-.974zM18.644 19.065a.498.498 0 100-.996.498.498 0 000 .996zM20.551 18.461a.498.498 0 100-.996.498.498 0 000 .996zM23.87 48.901a.498.498 0 10-.993.073.498.498 0 00.993-.073zM22.269 50.1a.498.498 0 10.072.994.498.498 0 00-.072-.994zM20.79 49.487a.498.498 0 10.072.993.498.498 0 00-.072-.993zM22.41 47.385a.498.498 0 10.994-.073.498.498 0 00-.993.073zM21.18 47.61a.498.498 0 10.072.994.498.498 0 00-.072-.993zM18.676 16.562a.498.498 0 10.934-.348.498.498 0 00-.934.348zM14.854 39.586a.498.498 0 100-.997.498.498 0 000 .997zM15.8 43.505a.498.498 0 10-.072-.993.498.498 0 00.072.993zM17.084 40.175a.498.498 0 10-.991-.098.498.498 0 00.991.098zM16.189 38.41a.498.498 0 100-.996.498.498 0 000 .996zM15.417 41.84a.498.498 0 100-.996.498.498 0 000 .997zM17.218 42.632a.498.498 0 100-.997.498.498 0 000 .997zM13.37 35.253a.498.498 0 100-.996.498.498 0 000 .996zM49.084 22.632a.498.498 0 10.617.781.498.498 0 00-.617-.781zM50.237 24.878a.497.497 0 10.782-.614.497.497 0 00-.782.614zM45.455 19.456a.498.498 0 10-.616-.781.498.498 0 00.616.781zM47.968 22.41a.498.498 0 10-.616-.78.498.498 0 00.616.78zM44.428 24.595a.498.498 0 10.616.781.498.498 0 00-.616-.781zM46.643 19.785a.498.498 0 10.616.781.498.498 0 00-.616-.781zM43.84 20.982a.497.497 0 10.781-.617.497.497 0 10-.781.617zM45.445 23.155a.498.498 0 10.617.782.498.498 0 00-.617-.782zM47.057 24.12a.497.497 0 10.781-.614.497.497 0 00-.781.614zM45.431 22.146a.497.497 0 10.782-.617.497.497 0 10-.782.617zM23.47 16.052a.498.498 0 10.997 0 .498.498 0 00-.996 0z" fill="#000"></path><path d="M32 9.223C16.56 9.223 4 19.44 4 32s12.56 22.777 28 22.777c15.438 0 27.998-10.217 27.998-22.777S47.438 9.223 32 9.223zm0 45.268C16.718 54.49 4.285 44.4 4.285 32 4.286 19.598 16.72 9.51 32 9.51c15.28 0 27.713 10.088 27.713 22.49S47.28 54.49 31.999 54.49z" fill="#000"></path><path d="M20.474 43.53c-.633 0-.633.982 0 .982s.633-.982 0-.982zM22.063 44.815c-.633 0-.633.982 0 .982s.633-.982 0-.982zM23.804 44.34c-.633 0-.633.982 0 .982s.633-.982 0-.982zM19.265 25.229c.633 0 .633-.982 0-.982s-.633.982 0 .982zM26.64 18.624c.634 0 .634-.982 0-.982-.632 0-.632.982 0 .982zM24.925 18.14c-.633 0-.633.982 0 .982s.633-.982 0-.982zM29.206 16.432c-.633 0-.633.982 0 .982s.633-.982 0-.982zM31.105 16.432c-.633 0-.633.982 0 .982s.633-.982 0-.982zM34.036 17.08c.633 0 .633-.982 0-.982s-.633.982 0 .982zM42.333 21.879c.633 0 .633-.982 0-.982s-.633.982 0 .982zM39.453 18.273c-.633 0-.633.982 0 .982s.633-.982 0-.982zM35.813 17.008c-.633 0-.633.982 0 .982s.633-.982 0-.982zM43.673 23.527c.633 0 .633-.982 0-.982s-.633.982 0 .982zM42.463 44.949c.633 0 .633-.982 0-.982s-.633.982 0 .982zM36.468 38.162a.498.498 0 100 .997.498.498 0 000-.997zM36.943 39.586a.498.498 0 100 .996.498.498 0 000-.996zM37.22 43.013a.498.498 0 10-.851-.517.498.498 0 00.851.517zM36.745 44.595a.498.498 0 10-.851-.517.498.498 0 00.851.517zM35.123 37.075a.498.498 0 10.851.517.498.498 0 00-.85-.517zM36.547 36.443a.498.498 0 10.851.516.498.498 0 00-.851-.516zM35.342 41.944c.633 0 .633-.983 0-.983s-.633.983 0 .983zM25.778 28.582a.498.498 0 10-.156.983.498.498 0 00.156-.983zM25.462 26.684a.498.498 0 10-.156.983.498.498 0 00.156-.983zM27.222 28.14a.498.498 0 100-.997.498.498 0 000 .996zM24.373 25.925a.498.498 0 100-.997.498.498 0 000 .997zM22.79 30.037a.498.498 0 100-.997.498.498 0 000 .997zM24.215 30.512a.498.498 0 100-.997.498.498 0 000 .997zM23.581 28.297a.498.498 0 10.001-.996.498.498 0 000 .996zM28.171 26.083a.498.498 0 100-.997.498.498 0 000 .997zM33.013 27.19a.498.498 0 100-.996.498.498 0 000 .996zM35.188 28.462a.498.498 0 100-.997.498.498 0 000 .997zM31.143 27.603a.498.498 0 100-.997.498.498 0 000 .997zM30.141 28.947a.498.498 0 100-.996.498.498 0 000 .996zM33.572 28.59a.498.498 0 10-.996 0 .498.498 0 00.996 0zM27.855 29.47a.498.498 0 10.996 0 .498.498 0 00-.996 0zM28.459 27.33a.498.498 0 10.997 0 .498.498 0 00-.997 0zM35.501 26.602a.498.498 0 100-.997.498.498 0 000 .997zM33.827 25.487a.498.498 0 100-.997.498.498 0 000 .997zM30.712 25.825a.498.498 0 100-.996.498.498 0 000 .996zM29.554 24.634a.498.498 0 10-.617-.78.498.498 0 00.617.78zM29.983 30.845a.498.498 0 100-.996.498.498 0 000 .996zM27.696 31.21a.498.498 0 10.997 0 .498.498 0 00-.997 0zM26.114 30.736a.498.498 0 10.997 0 .498.498 0 00-.997 0zM36.212 32.864a.497.497 0 10-.982-.156.497.497 0 00.982.156zM37.794 33.654a.498.498 0 10-.983-.155.498.498 0 00.983.155zM36.054 29.7a.497.497 0 10-.983-.156.497.497 0 00.983.156zM35.42 31.282a.498.498 0 10-.983-.156.498.498 0 00.983.156zM37.478 31.44a.498.498 0 10-.983-.155.498.498 0 00.983.155zM33.68 30.491a.498.498 0 10-.983-.156.498.498 0 00.983.156zM31.939 31.44a.498.498 0 10-.983-.156.498.498 0 00.983.156zM31.939 29.384a.498.498 0 10-.983-.156.498.498 0 00.983.156zM36.42 25.324a.498.498 0 10.157-.983.498.498 0 00-.156.983zM33.32 22.1a.498.498 0 10.001-.996.498.498 0 000 .997zM31.234 22.195a.498.498 0 10.997 0 .498.498 0 00-.997 0zM29.84 23.27a.498.498 0 100-.997.498.498 0 000 .996zM28.256 22.479a.498.498 0 100-.997.498.498 0 000 .997zM27.465 24.06a.498.498 0 100-.997.498.498 0 000 .997zM25.725 24.218a.498.498 0 100-.996.498.498 0 000 .996zM26.516 25.958a.498.498 0 100-.997.498.498 0 000 .997zM33.436 23.64a.498.498 0 100-.997.498.498 0 000 .996zM35.951 22.891a.498.498 0 10.997 0 .498.498 0 00-.997 0zM34.685 21.784a.498.498 0 10.996 0 .498.498 0 00-.996 0zM31.577 24.483a.498.498 0 10.156-.984.498.498 0 00-.156.984zM30.31 21.794a.498.498 0 10.156-.984.498.498 0 00-.156.984zM37.907 24.483a.498.498 0 10.156-.984.498.498 0 00-.156.984zM34.69 23.586a.498.498 0 10.983.155.498.498 0 00-.983-.155zM32.858 33.265a.498.498 0 10-.996 0 .498.498 0 00.996 0zM31.434 33.74a.498.498 0 10-.996 0 .498.498 0 00.997 0zM28.48 34.175a.498.498 0 00.517-.85.498.498 0 00-.517.85zM26.58 33.384a.498.498 0 00.518-.85.498.498 0 00-.517.85zM33.945 31.92a.498.498 0 00-.517.85.498.498 0 00.517-.85zM34.578 33.344a.498.498 0 00-.517.85.498.498 0 00.517-.85zM41.224 30.097a.5.5 0 10-.59-.805.5.5 0 00.59.805zM39.008 28.357a.5.5 0 10-.59-.805.5.5 0 00.59.805zM40.674 28.579a.5.5 0 10-.59-.806.5.5 0 00.59.806zM40.32 26.947a.5.5 0 10-.59-.806.5.5 0 00.59.806zM37.943 26.547a.5.5 0 00-.587-.806.5.5 0 00.587.806zM39.24 25.726a.5.5 0 10-.59-.806.5.5 0 00.59.806zM37.302 28.013a.497.497 0 10-.702-.704.497.497 0 00.702.704zM39.813 29.885a.497.497 0 10-.966.235.497.497 0 00.966-.235zM38.303 29.757a.497.497 0 10-.966.235.497.497 0 00.966-.235zM29.075 32.14c0 .632.983.632.983 0 0-.634-.983-.634-.983 0z" fill="#000"></path></svg><span>Listen to Podcasts and Articles</span></a></li></ul></div><div class="ExpandedNav_print__7d4vw" data-event-element="print edition"><h2 class="ExpandedNav_title__C8QcN ExpandedNav_printTitle__PKCL7">The Print Edition</h2><div class="ExpandedNav_printContainer__Lp_nj" data-action="magazine"><a href="/magazine/" data-action="cover" class="ExpandedNav_printImgLink__gcbdt"><img alt="" loading="lazy" class="Image_root__XxsOp Image_lazy__hYWHV ExpandedNav_printImg__hHeRU" src="https://www.theatlantic.com/magazine/images/current-issue.large.jpg" width="266" height="200"/></a><div class="ExpandedNav_printLinks__gNywy"><div class="ExpandedNav_topPrintLinks__UytSB"><a href="/magazine/" data-action="latest" class="ExpandedNav_latestIssue__iDXQm">Latest Issue</a><a href="/magazine/backissues/" data-action="past issues" class="ExpandedNav_pastIssues__nkE14">Past Issues</a></div><hr class="ExpandedNav_hr__5T2Ez"/><a href="https://accounts.theatlantic.com/products/gift" data-action="give a gift" class="ExpandedNav_giveAGift__vyp0c">Give a Gift</a></div></div></div></div></div></div></li><li class="Nav_navListItem__l2afO Nav_hideOnTablet__wyFPd Nav_searchLi__yxgD4"><button class="NavSearchButton_root__DcP_y" aria-label="Search The Atlantic" aria-expanded="false" aria-controls="nav-desktop-search" data-event-element="search icon" data-event-verb="opened" data-event-surface="search" data-event-module="search overlay"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16" class="NavSearchButton_searchIcon__Acpm1" data-action="Open Search"><path d="M15.85 15.15l-5.27-5.28a6 6 0 10-.71.71l5.28 5.27a.48.48 0 00.7 0 .48.48 0 000-.7zM1 6a5 5 0 115 5 5 5 0 01-5-5z"></path></svg></button><div data-event-surface="search" data-event-module="search overlay" class="SearchOverlay_root__lmUcH" hidden="" id="nav-desktop-search"><div data-focus-guard="true" tabindex="0" style="width:1px;height:0px;padding:0;overflow:hidden;position:fixed;top:1px;left:1px"></div><div data-focus-lock-disabled="false" aria-modal="true" aria-labelledby="search-label" role="dialog"><form method="GET" action="/search/" class="SearchOverlay_searchForm___U0R_" data-action="search submit"><div class="SearchInput_root__6XLPB"><div class="VisuallyHidden_root__yoK4r"><label for="search-input-:R2srl2mm:">Search The Atlantic</label></div><button type="submit" title="Submit" class="SearchInput_searchButton__u0CP0"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16" aria-hidden="true" width="20"><path d="M15.85 15.15l-5.27-5.28a6 6 0 10-.71.71l5.28 5.27a.48.48 0 00.7 0 .48.48 0 000-.7zM1 6a5 5 0 115 5 5 5 0 01-5-5z"></path></svg></button><input type="search" name="q" id="search-input-:R2srl2mm:" class="SearchInput_searchInput__5hWhI SearchInput_hideClear__re5AE" placeholder="Search The Atlantic..." autoComplete="off" required=""/></div><div class="QuickLinks_quickLinksContainer__F_iFd"><div class="QuickLinks_quickLinksHeading__ms7Ht">Quick Links</div><ul class="QuickLinks_quickLinksList__e7x66"><li class="QuickLinks_quickLinkListItem__59_09"><a class="QuickLinks_quickLink__w_Fp0" href="/projects/dear-therapist/" data-action="click link - quick link" data-label="Dear Therapist" data-event-element="quick link" data-event-position="1"><img alt="Dear Therapist" loading="lazy" class="Image_root__XxsOp Image_lazy__hYWHV QuickLinks_quickLinkImage__FTMBA" src="https://cdn.theatlantic.com/media/img/specialreports/lead/2020/10/14/Thumbnail.jpg" width="148" height="148"/><div class="QuickLinks_quickLinkLabel__TYtIC">Dear Therapist</div></a></li><li class="QuickLinks_quickLinkListItem__59_09"><a class="QuickLinks_quickLink__w_Fp0" href="/free-daily-crossword-puzzle/" data-action="click link - quick link" data-label="Crossword Puzzle" data-event-element="quick link" data-event-position="2"><img alt="Crossword Puzzle" loading="lazy" class="Image_root__XxsOp Image_lazy__hYWHV QuickLinks_quickLinkImage__FTMBA" src="https://cdn.theatlantic.com/assets/media/files/nav-crossword.png" width="148" height="148"/><div class="QuickLinks_quickLinkLabel__TYtIC">Crossword Puzzle</div></a></li><li class="QuickLinks_quickLinkListItem__59_09"><a class="QuickLinks_quickLink__w_Fp0" href="/archive/" data-action="click link - quick link" data-label="Magazine Archive" data-event-element="quick link" data-event-position="3"><img alt="Magazine Archive" loading="lazy" class="Image_root__XxsOp Image_lazy__hYWHV QuickLinks_quickLinkImage__FTMBA" src="https://cdn.theatlantic.com/media/files/archive-thumbnail.png" width="148" height="148"/><div class="QuickLinks_quickLinkLabel__TYtIC">Magazine Archive</div></a></li><li class="QuickLinks_quickLinkListItem__59_09"><a class="QuickLinks_quickLink__w_Fp0" href="https://accounts.theatlantic.com/accounts/subscription/" data-action="click link - quick link" data-label="Your Subscription" data-event-element="quick link" data-event-position="4"><img alt="Your Subscription" loading="lazy" class="Image_root__XxsOp Image_lazy__hYWHV QuickLinks_quickLinkImage__FTMBA" src="https://cdn.theatlantic.com/media/files/YourSubscription_300x300.jpg" width="148" height="148"/><div class="QuickLinks_quickLinkLabel__TYtIC">Your Subscription</div></a></li></ul></div><button type="button" aria-label="Close Search" class="SearchOverlay_closeButton___zntA" data-action="close search" data-event-verb="closed" data-event-element="close icon"><svg viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg" class="SearchOverlay_closeIcon__DrMMb"><path d="M9.525 8l6.159 6.159a1.078 1.078 0 11-1.525 1.525L8 9.524l-6.159 6.16a1.076 1.076 0 01-1.525 0 1.078 1.078 0 010-1.525L6.476 8 .315 1.841A1.078 1.078 0 111.841.316L8 6.476l6.16-6.16a1.078 1.078 0 111.524 1.525L9.524 8z" fill-rule="evenodd"></path></svg></button></form></div><div data-focus-guard="true" tabindex="0" style="width:1px;height:0px;padding:0;overflow:hidden;position:fixed;top:1px;left:1px"></div></div></li><li class="Nav_navListItem__l2afO Nav_hideOnTablet__wyFPd"><a class="Nav_navLink__34Bol" href="/most-popular/" data-action="popular">Popular</a></li><li class="Nav_navListItem__l2afO Nav_hideOnTablet__wyFPd"><a class="Nav_navLink__34Bol" href="/latest/" data-action="latest">Latest</a></li><li class="Nav_navListItem__l2afO Nav_hideOnTablet__wyFPd"><a class="Nav_navLink__34Bol" href="/newsletters/" data-action="newsletters">Newsletters</a></li></ul><div aria-hidden="true" class="Nav_middleContainer__7JzLF" data-event-element="wordmark"><a href="/" class="Nav_hideAboveMobile__1lhmL Nav_mobileBigALink__eWXD_" tabindex="-1" data-action="big a"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 87.83 134" class="Nav_mobileBigA__9PTCs Nav_hideOnMobile__IESg8"><path d="M24.48 95.13c-.56 0-.74-.37-.74-.93l13.08-55.88c.19-.94.93-.94 1.12 0L50.09 94.2c0 .56-.19.93-.75.93zM48.22.19a22.54 22.54 0 01-7.66 5.05c-.75.19-.94.37-1.13 1.12l-26.72 112.5c-2 9-4.67 10.66-11.77 11.22a.88.88 0 00-.94.93v2.06a.88.88 0 00.92.93h25.6a.88.88 0 00.93-.93V131a.88.88 0 00-.93-.93c-9.53 0-10.47-2.81-8.6-10.66l4.49-19.25a1.18 1.18 0 011.12-.93h26.74a1.19 1.19 0 011.13.93l5 23.18c1.12 5-.75 6.17-7.1 6.73a.88.88 0 00-.93.93v2.06a.88.88 0 00.93.93h37.62a.88.88 0 00.94-.93V131a.88.88 0 00-.94-.93c-5.79-.56-8.22-1.5-9.34-6.73L49.34.57c-.19-.56-.75-.75-1.12-.38"></path></svg></a><a href="/" class="Nav_navLink__34Bol" tabindex="-1" data-action="logo"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 214 33.24" class="Nav_logo__RLN3C"><path d="M39.39 13.2c-2.4 0-4.43 1.82-7 5.32-1.18 1.64-2.7 4-3.37 5-.38.51-.68.43-.47-.12l1.78-4.56 6.36-17.5C37 .62 34.46-.25 34 .62v.09c-1.09 2.32-3.12 3.08-6.75 2.95S16.32 1.52 10.8 1.52C3.88 1.52 0 5.78 0 10.8c0 2.82 1.85 4.64 4.34 4.55a2.27 2.27 0 002.41-1.81 1.2 1.2 0 00-1.56-1.43c-2.45.51-3.29-1.18-3.29-2.49 0-3.12 2.66-5.44 8.22-5.44 1.43 0 4.22.34 7.17.67-3.75 11.3-7.55 21.77-8.48 24.25a2.07 2.07 0 01-1.35 1.44c-1.34.42-1.77.46-2.61.67-1.27.3-1.06 1.35-.17 1.31 1.6-.09 3.67-.3 5.31-.3 2 0 5.61.17 6.16.21 1 .09 1.14-1.14.3-1.26-.59-.09-1.56-.25-2.49-.38-1.1-.13-1.43-.59-1.18-1.48.55-1.47 7-20.11 8.27-24 2 .25 3.71.42 4.84.5 2.33.14 4.57 0 6.5-1.41l-5.1 14.4-4.47 12.33c-.76 2 2.1 2.15 2.74.93a81.64 81.64 0 017.63-12.36c1.86-2.7 3.59-4.31 4.81-4.31.93 0 1.47.51 1.47 1.65 0 1.52-.71 3.88-2.15 7.89-1.89 5.23-2.61 6.62-3.24 6.66s-1.86-1.52-2.53-1.69a1.39 1.39 0 00-1.65.72c-.34.59-.12 2.49 2.74 2.62 3.42.16 6.33-3.34 8.35-8.94 1.39-3.8 1.73-5.74 1.73-7.13 0-2.7-1.26-3.97-3.33-3.97zm57.9 18.09c-2.15-.5-3-1.3-3-2.15l.09-1.77c0-1.3 1-20.49 1.22-23.36.17-2.11-2.24-2-3.25-.76l-2 2.57C87.89 8.9 78 21.68 73.17 27.67A11.5 11.5 0 0168 31.25c-.8.21-.72 1.06.17 1.06.71 0 2.82-.25 4.38-.25s4.43.12 5.15.16 1-.76 0-1c-2-.59-3-1-3-1.52s.46-1.22 1.56-2.74c.84-1.18 2.86-3.84 5.1-6.79H91c-.21 4.05-.46 8.31-.5 9.15a1.14 1.14 0 01-.93 1.14l-2.15.63c-.59.17-.85 1.27.08 1.23 2.11-.13 3.88-.3 4.81-.3 1.39 0 3.75.3 4.85.34s.94-.85.13-1.07zm-6-15.47c0 .76-.09 1.6-.13 2.49h-8.25c3.84-5.07 7.89-10.38 8.23-10.89s.67-.25.63.13c-.13 1.86-.34 5.27-.5 8.27zM55.08 13.5c-3.67-.17-7.76 4.09-9.7 10.5-1.9 6.2.21 8.77 2.53 8.77 1.69 0 4.51-2.19 6.07-4.72.55-.89.13-1.82-.71-.89-1.06 1.14-2.49 2.36-4 2.07-1-.17-1.94-1.9-.46-6.2 3.54-.17 7.71-2.19 8.77-5.53.92-2.88-.98-3.96-2.5-4zm.38 3.12c-.89 2.61-4 4.8-6.24 5.35 2.15-5.69 4.21-7.21 5.52-7.17.72 0 1.06.82.72 1.82zm53.94-1h3.42c.76 0 1.14-.21 1.3-.76.3-.72.13-1.06-.63-1.06h-3.42l1.65-4.38c.21-.59 0-.89-.34-.89h-1.77c-.46 0-.63.13-.84.72L107 13.83h-2.7c-.38 0-.68-.08-.93 1.06-.09.55 0 .76.55.76h2.4l-4.09 10.67a45.64 45.64 0 00-1.69 4.68c-.25 1.48.64 2.07 1.73 1.86 2.15-.38 5.23-2.62 8-6.12.76-1 .13-1.64-.63-.84a34.4 34.4 0 01-3.67 3.16c-1.1.72-1.64.21-1.26-.84zm38.04-1c.25-.59-.59-.76-2.53-1.13-.59-.13-.93.5-1.94 2.61a4 4 0 00-3.5-1.43c-3.08.08-6.88 2.86-10 7.12-2.49 3.42-3.25 5.78-2.78 8.31a3.11 3.11 0 003.08 2.52c2.32.08 4.64-2.11 7-4.52l1.48-1.48c.42-.42.8-.17.54.34a23.77 23.77 0 00-1.89 4.17c-.3 1.48.5 1.86 1.64 1.69 2.19-.29 5.61-2.32 8.23-5.94.75-1.06 0-1.65-.68-.85a26.62 26.62 0 01-3.75 3.29c-1.14.76-1.65.55-1.31-.34.17-.55.8-2.07 6.41-14.36zm-9.74 11c-2.66 2.45-4.81 4.22-6.29 4.22-1 0-1.47-.43-1.56-1.14-.25-1.86 1.44-4.68 2.83-6.58 2.4-3.16 5.36-5.78 7.25-5.78 1.31 0 2 .55 2.11 1.35.25 1.46-2.19 5.93-4.34 7.87zm58.58-12.71c-2.07 0-4.85 1.47-7.47 4.38-.84 1-.21 1.65.59.93a20.28 20.28 0 012.87-2.19c.89-.55 1.48-.13 1.22.67-.21.64-.84 2.2-1.3 3.25l-2.87 6.58c-.8 1.86-1.56 3.71-1.73 4.22-.38 1.31.29 2 1.35 2 2 0 4.77-1.65 7.42-4.6.84-1 .21-1.64-.59-.93a28 28 0 01-3.12 2.4c-.88.54-1.52.12-1.22-.68.21-.59.84-1.94 1.26-2.91l2.91-6.58c.85-1.94 1.82-4 2-4.55.32-1.28-.31-1.99-1.32-1.99zm2.53-10.21a2.39 2.39 0 00-2.53 2.15 2.09 2.09 0 001.85 2.45 2.43 2.43 0 002.49-2.11 2.08 2.08 0 00-1.81-2.49zm11.68 10.84c-3.71-.17-7.68 4.13-9.62 10.46s.17 8.77 2.62 8.77c1.69 0 4.51-2 6.2-4.72.55-.89.13-1.82-.72-.89-1.05 1.14-2.4 2.19-3.79 2.11s-2.37-2-.76-6.62c2.36-6.66 4-7.42 4.72-7.47s2.19 1.86 3.08 2.07a1.36 1.36 0 001.64-.71c.38-.72.14-2.83-3.37-3zm-23.95.29h-3.42l1.64-4.38c.22-.59 0-.89-.33-.89h-1.78c-.46 0-.63.13-.84.72l-1.73 4.55h-2.74c-.38 0-.67-.08-.93 1.06-.08.55.05.76.55.76h2.41l-4.09 10.67a43.34 43.34 0 00-1.69 4.68c-.26 1.48.63 2.07 1.73 1.86 2.15-.38 5.23-2.62 8-6.12.76-1 .13-1.64-.64-.84a34.33 34.33 0 01-3.68 3.16c-1.1.72-1.65.21-1.27-.84l4.71-12.6h3.42c.76 0 1.14-.21 1.31-.76.29-.69.12-1.03-.63-1.03zm-63.6 11.9a40.24 40.24 0 01-3.8 3.33c-1.1.72-1.64.21-1.26-.84L128.17.97c.17-.42.08-1-.51-1a58.6 58.6 0 00-6 .68c-.34.08-.51.59-.13.71l2.28.85c.46.17.51.38.21 1.14l-8.84 22.97a43.34 43.34 0 00-1.69 4.68c-.25 1.48.63 2.07 1.73 1.86 2.28-.38 5.52-2.62 8.35-6.29.76-1.01.13-1.64-.63-.84zm43.39.08l2.49-5c1.35-2.74 1.61-4 1.61-4.93 0-1.81-.93-2.74-2.83-2.74-2.66 0-4.77 2.11-8 6.66-.89 1.22-1.48 2.15-2.66 3.67-.38.47-.67.42-.46-.13l1.64-4.09a17 17 0 001.35-4.47c0-1.09-.46-1.6-1.64-1.6-1.44 0-3.25.76-6.41 4.77-1.14 1.47 0 1.64.38 1.18.63-.64 2-2.07 2.91-2.87s1.72-.55 1.39.42a18.36 18.36 0 01-.8 2.24l-5 12.27c-.68 1.69 2.53 2.07 3.08.8 1.73-4 5.52-9 7.08-11.22 2.28-3.25 4.26-5.48 5.69-5.48.76 0 1.1.42 1.1 1.22a5.83 5.83 0 01-.59 2l-3.54 7.55c-1 2-1.94 4.13-2.11 4.68-.42 1.31.3 2 1.43 2 2 0 4.77-1.65 7.43-4.6.84-1 .21-1.64-.59-.93a29 29 0 01-3.12 2.41c-.92.59-1.56.12-1.26-.72.21-.6.97-2.16 1.43-3.09z"></path></svg></a></div><div class="Nav_rightContainer__CBCcP"><ul class="NavAccountLinks_root__8VKLM" data-event-element="account links"><li class="NavAccountLinks_navListItem__Lxooj"><a data-action="Sign In" href="https://accounts.theatlantic.com/login/" class="NavAccountLinks_navLink__ctd7M NavAccountLinks_hideOnMobile__Eokx4">Sign In</a></li><li class="NavAccountLinks_navListItem__Lxooj"><a data-action="Subscribe" href="https://www.theatlantic.com/subscribe/navbar/" class="NavAccountLinks_subscribe__2DNuJ">Subscribe</a></li></ul></div></div></div></nav><div class="Nav_fixedPosPlaceholder__0nyHE"></div><div class="Nav_overlay__zlKnQ" data-testid="overlay"></div><div class="BreakingNewsBar_root__pmOIb"></div><main id="main-content" data-category="story page" data-event-surface="article" data-flatplan-layout="standard"><gpt-ad class="GptAd_root__pAvcS Leaderboard_root__gbBIq" format="leaderboard" sizes-at-0="" sizes-at-976="leaderboard"></gpt-ad><article class="ArticleLayout_article__RHFMN article-content-body"><header class="ArticleHero_root__3w7kV ArticleHero_articleStandard__2tcdv" data-event-module="hero"><div class=""><div class="ArticleHero_defaultArticleLockup__vb8lz"><div class="ArticleHero_rubric__e4rjD"><div class="ArticleRubric_root__HNhbf" id="rubric" data-flatplan-rubric="true"><a class="ArticleRubric_link__nl9hy" href="https://www.theatlantic.com/science/" data-action="click link - section rubric" data-label="https://www.theatlantic.com/science/" data-event-element="rubric">Science</a></div></div><div class="ArticleHero_title__PQ4pC"><h1 class="ArticleTitle_root__VrZaG" data-flatplan-title="true">An Existential Problem in the Search for Alien Life</h1></div><div class="ArticleHero_dek__EqdkK" data-flatplan-description="true"><p class="ArticleDek_root__P3leE">We don’t really know what life is in the first place.</p></div><div class="ArticleHero_byline__iFT6A"><div class="ArticleBylines_root__IBR5V"><address id="byline">By <a class="ArticleBylines_link__kNP4C" href="https://www.theatlantic.com/author/jaime-green/" data-action="click author - byline" data-label="https://www.theatlantic.com/author/jaime-green/" data-event-element="author" data-flatplan-author-link="true">Jaime Green</a></address></div></div></div><div class="ArticleLeadArt_root__nRSLU"><figure class="ArticleLeadFigure_root__Bj81R ArticleLeadFigure_standard__20Izv"><div class="ArticleLeadFigure_media__R1npW" data-flatplan-lead_figure_media="true"><picture><img alt="Illustration of a flower in space" class="Image_root__XxsOp ArticleLeadArt_image__HZS4B" sizes="(min-width: 976px) 976px, 100vw" srcSet="https://cdn.theatlantic.com/thumbor/BObNhpaFMEy0usHGw7ytZuDaIe8=/0x0:2000x1125/750x422/media/img/mt/2023/12/what_is_life_/original.jpg 750w, https://cdn.theatlantic.com/thumbor/_JRdcb79qt4Ad4YZTWCKDKFsrVk=/0x0:2000x1125/828x466/media/img/mt/2023/12/what_is_life_/original.jpg 828w, https://cdn.theatlantic.com/thumbor/75t4GJf5WHxA3zYoMWFQ32Jb8Yk=/0x0:2000x1125/960x540/media/img/mt/2023/12/what_is_life_/original.jpg 960w, https://cdn.theatlantic.com/thumbor/ISqFpnaRM4gIbuua4EFP1lpm-i8=/0x0:2000x1125/976x549/media/img/mt/2023/12/what_is_life_/original.jpg 976w, https://cdn.theatlantic.com/thumbor/1gMWMUEgoXt_RjV2kkhtYvIHVQA=/0x0:2000x1125/1952x1098/media/img/mt/2023/12/what_is_life_/original.jpg 1952w" src="https://cdn.theatlantic.com/thumbor/75t4GJf5WHxA3zYoMWFQ32Jb8Yk=/0x0:2000x1125/960x540/media/img/mt/2023/12/what_is_life_/original.jpg" id="article-lead-image" width="960" height="540"/></picture></div><figcaption class="ArticleLeadFigure_caption__Byu7W ArticleLeadFigure_standardCaption__PsDkd" data-flatplan-lead_figure_caption="true">Ben Kothe / The Atlantic</figcaption></figure></div></div><div class="ArticleHero_articleUtilityBar__JbQFj"><div class="ArticleHero_timestamp__bKhcB"><time class="ArticleTimestamp_root__b3bL6" dateTime="2023-12-05T12:00:00Z" data-flatplan-timestamp="true">December 5, 2023</time> </div><div class="ArticleHero_articleUtilityBarTools__ZHw8s"><div class="ArticleShare_root__Mq0RB"><button class="ArticleShare_text__oQKBy ArticleShare_shareButton__X0cIe" aria-haspopup="true" aria-controls=":R1i5ioomm:" aria-expanded="false" aria-label="Open Share Menu" data-action="click share - expand" data-event-verb="shared" data-event-element="share dropdown">Share<svg width="15" height="15" fill="none" xmlns="http://www.w3.org/2000/svg" class="ArticleShare_shareIcon__G4iq1"><path fill-rule="evenodd" clip-rule="evenodd" d="M7.335.272a.25.25 0 01.337 0l4.623 4.204a.25.25 0 01.017.353l-.336.37a.25.25 0 01-.353.016L8.004 1.926v7.9a.25.25 0 01-.25.25h-.5a.25.25 0 01-.25-.25V1.924l-3.62 3.291a.25.25 0 01-.353-.016l-.336-.37a.25.25 0 01.016-.353L7.335.272zM.5 7.545a.25.25 0 00-.25.25v6.75c0 .138.112.25.25.25h14a.25.25 0 00.25-.25v-6.75a.25.25 0 00-.25-.25H14a.25.25 0 00-.25.25v6H1.25v-6a.25.25 0 00-.25-.25H.5z" fill="#000"></path></svg></button></div><button class="SaveButton_saveButton__7LYFZ" aria-label="Save"><span class="SaveButton_text__fiZgx">Save </span><svg width="12" height="16" fill="none" xmlns="http://www.w3.org/2000/svg" class="SaveButton_icon__HFNiD SaveButton_unsaved__bP4MN"><path fill-rule="evenodd" clip-rule="evenodd" d="M6 10.828l5 3.31V1H1v13.139l5-3.31zM.776 15.486A.5.5 0 010 15.07V.5A.5.5 0 01.5 0h11a.5.5 0 01.5.5v14.57a.5.5 0 01-.776.416L6.138 12.12a.25.25 0 00-.276 0L.776 15.486z" fill="currentColor"></path><path fill-rule="evenodd" clip-rule="evenodd" d="M5.572 8.75c0 .138.111.25.25.25h.5a.25.25 0 00.25-.25V6.57H8.75A.25.25 0 009 6.32v-.5a.25.25 0 00-.25-.25H6.572V3.25a.25.25 0 00-.25-.25h-.5a.25.25 0 00-.25.25v2.32H3.25a.25.25 0 00-.25.25v.5c0 .138.112.25.25.25h2.322v2.18z" fill="currentColor"></path></svg></button></div></div><gpt-ad class="GptAd_root__pAvcS ArticleInjector_root__I7x9v LeadArticleAd_root__tdCqm s-native s-native--standard s-native--streamline" format="injector" sizes-at-0="mobile-wide" targeting-pos="injector-article-start" sizes-at-976="desktop-wide"></gpt-ad><div class="ArticleInjector_clsAvoider__dqIAm" style="--placeholderHeight:298px"></div></header><div class="ArticleAudio_root__4Qcq3" data-view-action="view - audio player - start" data-view-label="676238" data-event-module="audio player" data-event-content-type="narrated" data-event-module-state="start" data-event-view="true"><div class="ArticleAudio_container__b5Yj2"><div><div class="ArticleAudio_imgContainer__qDu_f"><img alt="Illustration of a flower in space" class="Image_root__XxsOp ArticleAudio_img__BFda3" sizes="80px" srcSet="https://cdn.theatlantic.com/thumbor/u90ma_Gyh5ZHbYOTlJLfA4RAxqs=/438x0:1563x1125/80x80/media/img/mt/2023/12/what_is_life_/original.jpg 80w, https://cdn.theatlantic.com/thumbor/GzCOUn8KDUdDyPexWX_07_Jc-tQ=/438x0:1563x1125/96x96/media/img/mt/2023/12/what_is_life_/original.jpg 96w, https://cdn.theatlantic.com/thumbor/gQ5N9hOF4B9htnGRg9MnYltxRwI=/438x0:1563x1125/128x128/media/img/mt/2023/12/what_is_life_/original.jpg 128w, https://cdn.theatlantic.com/thumbor/vNzZPqC6cm6E4OhChvXNIG9uDu4=/438x0:1563x1125/160x160/media/img/mt/2023/12/what_is_life_/original.jpg 160w, https://cdn.theatlantic.com/thumbor/rK1svmQ9sNIjuARVLTd109pwpMo=/438x0:1563x1125/192x192/media/img/mt/2023/12/what_is_life_/original.jpg 192w, https://cdn.theatlantic.com/thumbor/IZU_rJp_Ef4E3CWpH6NELcpwKz0=/438x0:1563x1125/256x256/media/img/mt/2023/12/what_is_life_/original.jpg 256w, https://cdn.theatlantic.com/thumbor/KXwq6YWf-Ao3_DWt0JjiR0syZPE=/438x0:1563x1125/384x384/media/img/mt/2023/12/what_is_life_/original.jpg 384w, https://cdn.theatlantic.com/thumbor/qiRO_AOM_U9lVY_MuYeiEyqsevs=/438x0:1563x1125/512x512/media/img/mt/2023/12/what_is_life_/original.jpg 512w" src="https://cdn.theatlantic.com/thumbor/u90ma_Gyh5ZHbYOTlJLfA4RAxqs=/438x0:1563x1125/80x80/media/img/mt/2023/12/what_is_life_/original.jpg" width="80" height="80"/></div></div><div><div class="ArticleAudio_text__DsxgL"><span>Listen</span><span class="ArticleAudio_speed__YBmbh"><button class="ArticleAudio_speedBtn__tipaO">-</button><span>1.0x</span><button class="ArticleAudio_speedBtn__tipaO">+</button></span></div><div class="ArticleAudio_player__hOjo_"><div class="ArticleAudio_progressBarContainer__IbGRE"><input data-event-verb="scrubbed" class="ArticleAudio_slider__AnzMp" data-event-element="slider" type="range" max="842.61" style="--player-elapsed:0;--player-duration:842.61" role="progressbar" value="0"/></div><div class="ArticleAudio_timeContainer__8S55D" aria-hidden="true"><span class="ArticleAudio_time__TIPIP">0:00</span><span class="ArticleAudio_time__TIPIP ArticleAudio_duration__qdjYp">14:02</span></div><div class="ArticleAudio_buttonContainer__c3yS8"><button id="rewind" class="ArticleAudio_button__Xvn0e" disabled="" aria-label="rewind 15 seconds" data-action="click button - audio player - skip backward" click-event-element="skip backwards" data-label="676238" data-event-verb="rewound"><svg width="40" height="40" fill="none" xmlns="http://www.w3.org/2000/svg" class="ArticleAudio_rewindFwd__7N__7" aria-hidden="true"><path fill-rule="evenodd" clip-rule="evenodd" d="M10.344 5.314l-3.563 7.83 8.563.83-2.126-3.682a11.945 11.945 0 016-1.606c6.628 0 12 5.373 12 12 0 6.628-5.372 12-12 12A11.995 11.995 0 018.82 26.682l-1.732 1c2.42 4.188 6.946 7.006 12.13 7.006 7.732 0 14-6.268 14-14 0-7.733-6.268-14-14-14-2.55 0-4.941.681-7 1.873l-1.874-3.246z" fill="currentColor"></path><path d="M11.842 23.607h2.368v-4.615l-1.783.997-.691-1.263 2.686-1.49h1.503v6.371h2.368v1.33h-6.45v-1.33zm13.857-1.25c0 1.57-1.263 2.7-3.165 2.713-1.064.013-1.982-.186-3.312-.758l.599-1.277c1.117.492 1.769.665 2.593.665.878 0 1.61-.425 1.61-1.237 0-.678-.559-1.13-1.437-1.13-.518 0-1.17.173-1.822.505l-1.117-.439.28-4.163h5.266v1.33h-4.017l-.106 1.902a3.645 3.645 0 011.822-.465c1.69 0 2.806.997 2.806 2.354z" fill="currentColor"></path></svg></button><button class="ArticleAudio_playButton__JvBX0" aria-label="play" data-event-element="play pause button" data-event-verb="played"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 12 12" class="ArticleAudio_play__bBFV4" aria-hidden="true" data-action="click button - audio player - play" data-label="676238"><path fill="currentColor" d="M3 12V0l9 6-9 6z"></path></svg></button><button id="fast-forward" class="ArticleAudio_button__Xvn0e" disabled="" aria-label="fast forward 15 seconds" data-action="click button - audio player - skip forward" click-event-element="skip forward" data-label="676238" data-event-verb="skipped"><svg width="40" height="40" fill="none" xmlns="http://www.w3.org/2000/svg" class="ArticleAudio_rewindFwd__7N__7" aria-hidden="true"><path fill-rule="evenodd" clip-rule="evenodd" d="M29.656 5.314l3.562 7.83-8.562.83 2.126-3.682a11.944 11.944 0 00-6-1.606c-6.628 0-12 5.373-12 12 0 6.628 5.372 12 12 12 4.443 0 8.323-2.415 10.397-6.005l1.733 1c-2.42 4.188-6.946 7.006-12.13 7.006-7.733 0-14-6.268-14-14 0-7.733 6.267-14 14-14 2.55 0 4.94.681 7 1.873l1.874-3.246z" fill="currentColor"></path><path d="M14.28 23.607h2.367v-4.615l-1.782.997-.692-1.263 2.687-1.49h1.503v6.371h2.367v1.33h-6.45v-1.33zm13.857-1.25c0 1.57-1.264 2.7-3.166 2.713-1.064.013-1.981-.186-3.311-.758l.598-1.277c1.117.492 1.77.665 2.594.665.878 0 1.61-.425 1.61-1.237 0-.678-.56-1.13-1.437-1.13-.519 0-1.17.173-1.822.505l-1.118-.439.28-4.163h5.267v1.33h-4.017l-.106 1.902a3.645 3.645 0 011.822-.465c1.689 0 2.806.997 2.806 2.354z" fill="currentColor"></path></svg></button></div></div></div></div><p class="ArticleAudio_promo__4zkGZ">Produced by ElevenLabs and <a class="ArticleAudio_link__bjoip" href="https://newsoveraudio.com/download"> News Over Audio (Noa)</a> using AI narration. Listen to more stories on the Noa app.</p></div><section class="ArticleBody_root__2gF81" data-event-module="article body" data-flatplan-body="true"><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">In 2020, a team of researchers found something surprising in the high clouds of Venus. Earth-based telescopes detected the spectral signature of phosphine, a simple molecule that should have no business persisting in those extremely acidic clouds. Cautiously excited, the researchers wrote that the phosphine could be the result of “unknown photochemistry or geochemistry”—or, they noted almost coyly, “possibly life.”</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">It was a thrilling possibility. <a data-event-element="inline link" href="https://www.earth.com/news/sign-of-life-found-in-the-clouds-surrounding-venus/">“Signs of Life Found in the Clouds Surrounding Venus,”</a> one headline blared; another, <a data-event-element="inline link" href="https://www.thecut.com/article/life-on-venus-phosphine.html">“Aliens Were on Venus This Whole Time?!”</a> It was also, it turned out, a false alarm. The phosphine not only wasn’t a signal of life, but probably wasn’t even there at all, a swing-and-a-miss of data interpretation. The clouds of Venus were still, as far as anyone knew, as uninhabited as they’d always seemed.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">Scientists took the false alarm in stride. <em>Back to the drawing board</em>, they seemed to say, shrugging—or back to their telescopes at least. This is how science works, after all: gradually, in small steps, in announcements and skepticism and reconsideration of the data. It’s even harder when the subject of study is extraterrestrial. Venus is the closest possible home to alien life, but there’s no way to go and scoop a sample of its atmosphere to put under a telescope. The search for alien life is done remotely, by interpretation and inference. The suspected phosphine—considered a “biosignature” by astrophysicists, because phosphine on Earth is only ever abundant when it’s a product of life—wasn’t even observed directly. Instead, the researchers detected it by analyzing wavelengths of light that could hint at what molecules might be in Venus’s atmosphere. The researchers were searching for a sign of a sign of life. There was a lot of room for error.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">The search for extraterrestrial life is not the kind that is likely to yield an aha moment—not in the sense that, with the tools currently available, scientists are going to look at data brought in from the cosmos and instantly declare, “Yes, this is life.” There are too many technical hurdles, too many variables that will need time to be sorted out. And even accounting for those issues, another obstacle exists—an enduring puzzle that tests the limits of science. The fact is, we still don’t know what life is.</p><hr class="ArticleLegacyHtml_root__WFd2I c-section-divider ArticleLegacyHtml_standard__kC_zi"/><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">Hold a rock next to a flower and you’re probably confident you know the difference. But since the days of Aristotle, scientists and philosophers have struggled to draw a precise line between what is living and what is not, often returning to criteria such as self-organization, metabolism, and reproduction but never finding a definition that includes, and excludes, all the right things. If you say life consumes fuel to sustain itself with energy, you risk including fire; if you demand the ability to reproduce, you exclude mules. NASA hasn’t been able to do better than a working definition: “Life is a self-sustaining chemical system capable of Darwinian evolution.” It’s a decent way to describe life on Earth, but it lacks practical application. If humans found something on another planet that seemed to be alive, how much time would we have to sit around and wait for it to evolve?</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">The problem is that, in any attempt to define life, we’re inherently constrained by human intuition and the one example we have so far that informs it. The only life we know is life on Earth. Some scientists call this the n=1 problem, where <em>n</em> is the number of examples from which we can generalize. We have no idea if earthly life is average in the cosmos or some sort of freak outlier. With all the varied chemistries of other planets, all the contingencies that drive evolution, all the ways that matter and energy interact—who knows how strange life on another world might be? What if life as we know it is the wrong life to be looking for?</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">What we really want is more than a definition of life. We want to know what life, fundamentally, <em>is</em>. For that kind of understanding, scientists turn to theories. A theory is a scientific fundamental. It not only answers questions, but frames them, opening new lines of inquiry. It explains our observations and yields predictions for future experiments to test. Consider the difference between <em>defining</em> gravity as “the force that makes an apple fall to the ground” and <em>explaining</em> it, as Newton did, as the universal attraction between all particles in the universe, proportional to the product of their masses and so on. A definition tells us what we already know; a theory changes how we understand things.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">In recent years, the potential rewards of unlocking a theory of life have captivated a clutch of researchers from a diverse set of disciplines. “There are certain things in life that seem very hard to explain,” Sara Imari Walker, a physicist at Arizona State University who has been at the vanguard of this work, told me. “If you scratch under the surface, I think there is some structure that suggests formalization and mathematical laws.” It has long been presumed that although theories can explain physics and chemistry, biology is too messy, too contingent, to be boiled down to math and formulas. In 1997, the renowned biologist Ernst Mayr wrote that although the molecules that compose living organisms obey the laws of physics just as all molecules do, “organisms are fundamentally different from inert matter.” There is a threshold that matter can cross, beyond which the laws of physics do not explain or predict what happens; on the other side of that threshold is life.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">But Walker doesn’t think about life as a biologist—or an astrobiologist—does. When she talks about signs of life, she doesn’t talk about carbon, or water, or RNA, or phosphine. She reaches for different examples: a cup, a cellphone, a chair. These objects are not alive, of course, but they’re clearly products of life. In Walker’s view, this is because of their complexity. Life brings complexity into the universe, she says, in its own being and in its products, because it has memory: in DNA, in repeating molecular reactions, in the instructions for making a chair.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">Lee Cronin, a chemistry professor at the University of Glasgow and Walker’s main collaborator, told me that when Walker first explained to him her ideas for a theory of life, “I was like, ‘I have no clue what you’re talking about. But it feels like we are saying something super similar.’” Cronin studies the origin of life, also a major interest of Walker’s, and it turned out that, when expressed in math, their ideas were essentially the same. They had both zeroed in on complexity as a hallmark of life. Cronin is devising a way to systematize and measure complexity, which he calls Assembly Theory. He measures the complexity of an object—say, a molecule—by calculating the number of steps necessary to put the object’s smallest building blocks together in that certain way. His lab has found, for example, when testing a wide range of molecules, that those with an “assembly number” above 15 were exclusively the products of life. Life makes some simpler molecules, too, but only life seems to make molecules that are so complex.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">No one expects to find an alien cellphone in Mars’s Jezero Crater. But Walker’s whole notion is that it’s not only theoretically possible but genuinely achievable to identify something smaller—much smaller—that still nonetheless simply must be the result of life. The model would, in a sense, function like biosignatures as an indication of life that could be searched for. But it would drastically improve and expand the targets. Walker would use the theory to predict what life on a given planet might look like. It would require knowing a lot about the planet—information we might have about Venus, but not yet about a distant exoplanet—but, crucially, would not depend at all on how life on Earth works, what life on Earth might do with those materials. Without the ability to divorce the search for alien life from the example of life we know, Walker thinks, a search is almost pointless. “Any small fluctuations in simple chemistry can actually drive you down really radically different evolutionary pathways,” she told me. “I can’t imagine [life] inventing the same biochemistry on two worlds.”</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true"></p><hr class="ArticleLegacyHtml_root__WFd2I c-section-divider ArticleLegacyHtml_standard__kC_zi"/><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">Devising a universal theory for life is an ambitious project, to say the least. The scientists I’ve spoken with who are leading the search for biosignatures tend to welcome Walker’s unconventional approach, on the grounds that the more tools available, the merrier. Even so, no one is abandoning their search in the hopes that humanity will soon solve the mystery of life. After all, finding <em>any</em> examples of alien life—Earthlike or not, by whatever means possible—would radically advance our ability to understand the phenomenon.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">Walker’s approach is grounded in the work of, among others, the philosopher of science Carol Cleland, who wrote <em><a data-event-element="inline link" href="https://tertulia.com/book/the-quest-for-a-universal-theory-of-life-searching-for-life-as-we-don-t-know-it-carol-e-cleland/9780521873246?affiliate_id=atl-347">The Quest for a Universal Theory of Life</a></em>. But Cleland doesn’t share Walker’s ambitions that a theory may be within reach; instead she warns that any theory of life, just like a definition, cannot be constrained by the one example of life we currently know. “It’s a mistake to start theorizing on the basis of a single example, even if you’re trying hard not to be Earth-centric. Because you’re going to be Earth-centric,” Cleland told me. In other words, until we find other examples of life, we won’t have enough data from which to devise a theory. Abstracting away from Earthliness isn’t a way to be agnostic, Cleland argues. It’s a way to be too abstract.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">It’s a knot easy to get tied up in: We don’t have a theory of life to guide the search for extraterrestrials, but we need to find extraterrestrial life before we can understand life with a theory. Instead of provincially looking for life as we know it, Cleland calls for a more flexible search guided by what she calls “tentative criteria.” Such a search would have a sense of what we’re looking for, but also be open to anomalies that challenge our preconceptions, detections that aren’t life as we expected but aren’t familiar not-life either—neither a flower nor a rock. It’s unsatisfying if you want a firm answer or a quick one, but it speaks to the hope that exploration and discovery might truly expand our understanding of the cosmos and our own world.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">Cleland’s approach ends up sounding much like a lot of the work being done hunting for biosignatures today. A true discovery of phosphine in the clouds of Venus would be an anomaly for sure, and absolutely challenge preconceptions about the kinds of chemistry happening in those clouds. Other work in the field seeks similar surprises. The astrobiologist Kimberley Warren-Rhodes studies life on Earth that lives at the borders of known habitability, such as in Chile’s Atacama Desert. The point of her experiments is to better understand how life might persist—and how it might be found—on Mars. “Biology follows some rules,” she told me. The more of those rules you observe, the better sense you have of where to look on other worlds. In this light, the most immediate concern in our search for extraterrestrial life might be less that we only know about life on Earth, and more that we don’t even know that much about life on Earth in the first place. “I would say we understand about 5 percent,” Warren-Rhodes estimates of our cumulative knowledge. N=1 is a problem, and we might be at more like n=.05.</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">When I talk with people about a theory of life, which lately is my best attempt at small talk, I reach for the theory of gravity as a familiar parallel. Someone might ask, “Okay, so in terms of gravity, where are we in terms of our understanding of life? Like, Newton?” Further back, further back, I say. Walker compares us to pre-Copernican astronomers, reliant on epicycles, little orbits within orbits, to make sense of the motion we observe in the sky. Cleland has put it in terms of chemistry, in which case we’re alchemists, not even true chemists yet. We understand so little, and we think we’re ready to find other life?</p><p class="ArticleParagraph_root__4mszW" data-flatplan-paragraph="true">Maybe we’ll never be ready. Yet how could we not search? Right now, the James Webb Space Telescope is peering into exoplanet atmospheres for spectral signatures. The Perseverance rover is bottling up soil samples on Mars for a future mission to bring to Earth to study. How could we not trawl the cosmos for anything that could help us understand our place in it, our kinship lines, and how this life, on Earth, came to be? And so we try. We scour other worlds, scan their clouds. And scratch beneath the surface, for the theory that might explain it all in equation and abstraction, to see the deeper truth beneath what we can see.</p><div class="ArticleBody_divider__GpNxD" id="article-end"></div></section><div data-event-module="footer"><div class="ArticleWell_root__fueCa"><div data-event-module="author footer" class="ArticleFooter_authorFooter__5NsdY"><div class="SectionHeading_root__3GnqT"><h3 class="SectionHeading_heading__iNkek">About the Author</h3></div><div><div class="ArticleBio_root__ua8zj"><address id="article-writer-0" class="ArticleBio_author__6pDyl" data-event-element="author" data-event-position="1" data-flatplan-bio="true"><div class="ArticleBio_content__O0ZVF ArticleBio_noHeadshotContent__RrLmd"><div class="ArticleBio_bioSection__Hef4P"><div data-flatplan-bio="true"><a href="https://www.theatlantic.com/author/jaime-green/" class="author-link" data-label="https://www.theatlantic.com/author/jaime-green/" data-action="click author - name" >Jaime Green</a> is a writer based in Connecticut. She is the author of <em>The Possibility of Life: Science, Imagination, and Our Quest for Kinship in the Cosmos</em>.</div><div class="ArticleBio_moreStories__LKpwT"><p class="ArticleBio_contentHeading__cmbmT">More Stories</p><a class="ArticleBio_storyLink__xuRiU" href="https://www.theatlantic.com/science/archive/2023/04/carl-sagan-contact-book-alien-intelligence/673748/" data-event-element="more stories" data-event-position="1"><p>Why Does <em>Contact</em> Say So Much About God?</p></a></div></div></div></address></div></div></div></div><div></div></div><gpt-ad class="GptAd_root__pAvcS ArticleInjector_root__I7x9v s-native s-native--standard s-native--streamline" format="injector" sizes-at-0="mobile-wide,native,house" targeting-pos="injector-most-popular" sizes-at-976="desktop-wide,native,house"></gpt-ad><div class="ArticleInjector_clsAvoider__dqIAm"></div></article><div></div></main><div></div><div></div></div></div><script id="__NEXT_DATA__" type="application/json">{"props":{"isLoggedIn":false,"hasPaywallAccess":false,"hasAdFree":false,"pageProps":{"id":"BlogArticle:676238","isTnfCompatible":true,"layout":"standard","hasMeter":true,"url":"https://www.theatlantic.com/science/archive/2023/12/defining-life-existentialism-scientific-theory/676238/","dateModified":"2023-12-05T17:45:56Z","__typename":"BlogArticle","notFound":false,"urqlState":{"1062693879":{"data":"{\"article\":{\"primaryCategory\":{\"__typename\":\"Channel\"},\"editorialProject\":null,\"__typename\":\"BlogArticle\"}}"},"1075710368":{"data":"{\"article\":{\"id\":\"BlogArticle:676238\",\"isTnfCompatible\":true,\"layout\":\"standard\",\"hasMeter\":true,\"url\":\"https://www.theatlantic.com/science/archive/2023/12/defining-life-existentialism-scientific-theory/676238/\",\"dateModified\":\"2023-12-05T17:45:56Z\",\"__typename\":\"BlogArticle\"}}"},"2021745665":{"data":"{\"breakingNews\":null}"},"3167350833":{"data":"{\"article\":{\"__typename\":\"BlogArticle\",\"id\":\"BlogArticle:676238\",\"authors\":[{\"url\":\"https://www.theatlantic.com/author/jaime-green/\",\"displayName\":\"Jaime Green\",\"__typename\":\"Author\",\"id\":\"Author:38296\",\"biography\":{\"default\":\"\u003ca href=\\\"https://www.theatlantic.com/author/jaime-green/\\\" class=\\\"author-link\\\" data-label=\\\"https://www.theatlantic.com/author/jaime-green/\\\" data-action=\\\"click author - name\\\" \u003eJaime Green\u003c/a\u003e is a writer based in Connecticut. She is the author of \u003cem\u003eThe Possibility of Life: Science, Imagination, and Our Quest for Kinship in the Cosmos\u003c/em\u003e.\",\"__typename\":\"Biography\"},\"headshot\":null,\"river\":{\"edges\":[{\"cursor\":\"MjAyMy0xMi0wNSAwNzowMDowMHw2NzYyMzg=\",\"node\":{\"id\":\"BlogArticle:676238\",\"title\":\"An Existential Problem in the Search for Alien Life\",\"url\":\"https://www.theatlantic.com/science/archive/2023/12/defining-life-existentialism-scientific-theory/676238/\",\"__typename\":\"BlogArticle\"},\"__typename\":\"PromoEdge\"},{\"cursor\":\"MjAyMy0wNC0xNyAxMzo0NjowMHw2NzM3NDg=\",\"node\":{\"id\":\"BlogArticle:673748\",\"title\":\"Why Does \u003cem\u003eContact\u003c/em\u003e Say So Much About God?\",\"url\":\"https://www.theatlantic.com/science/archive/2023/04/carl-sagan-contact-book-alien-intelligence/673748/\",\"__typename\":\"BlogArticle\"},\"__typename\":\"PromoEdge\"}],\"__typename\":\"RiverConnection\"},\"slug\":\"jaime-green\",\"socialMedia\":[]}],\"authorContext\":null,\"categories\":[],\"content\":[{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"In 2020, a team of researchers found something surprising in the high clouds of Venus. Earth-based telescopes detected the spectral signature of phosphine, a simple molecule that should have no business persisting in those extremely acidic clouds. Cautiously excited, the researchers wrote that the phosphine could be the result of “unknown photochemistry or geochemistry”—or, they noted almost coyly, “possibly life.”\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"It was a thrilling possibility. \u003ca data-event-element=\\\"inline link\\\" href=\\\"https://www.earth.com/news/sign-of-life-found-in-the-clouds-surrounding-venus/\\\"\u003e“Signs of Life Found in the Clouds Surrounding Venus,”\u003c/a\u003e one headline blared; another, \u003ca data-event-element=\\\"inline link\\\" href=\\\"https://www.thecut.com/article/life-on-venus-phosphine.html\\\"\u003e“Aliens Were on Venus This Whole Time?!”\u003c/a\u003e It was also, it turned out, a false alarm. The phosphine not only wasn’t a signal of life, but probably wasn’t even there at all, a swing-and-a-miss of data interpretation. The clouds of Venus were still, as far as anyone knew, as uninhabited as they’d always seemed.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"Scientists took the false alarm in stride. \u003cem\u003eBack to the drawing board\u003c/em\u003e, they seemed to say, shrugging—or back to their telescopes at least. This is how science works, after all: gradually, in small steps, in announcements and skepticism and reconsideration of the data. It’s even harder when the subject of study is extraterrestrial. Venus is the closest possible home to alien life, but there’s no way to go and scoop a sample of its atmosphere to put under a telescope. The search for alien life is done remotely, by interpretation and inference. The suspected phosphine—considered a “biosignature” by astrophysicists, because phosphine on Earth is only ever abundant when it’s a product of life—wasn’t even observed directly. Instead, the researchers detected it by analyzing wavelengths of light that could hint at what molecules might be in Venus’s atmosphere. The researchers were searching for a sign of a sign of life. There was a lot of room for error.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"The search for extraterrestrial life is not the kind that is likely to yield an aha moment—not in the sense that, with the tools currently available, scientists are going to look at data brought in from the cosmos and instantly declare, “Yes, this is life.” There are too many technical hurdles, too many variables that will need time to be sorted out. And even accounting for those issues, another obstacle exists—an enduring puzzle that tests the limits of science. The fact is, we still don’t know what life is.\"},{\"__typename\":\"ArticleLegacyHtml\",\"tagName\":\"HR\",\"idAttr\":\"\",\"className\":\"c-section-divider\",\"style\":\"\",\"innerHtml\":\"\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"Hold a rock next to a flower and you’re probably confident you know the difference. But since the days of Aristotle, scientists and philosophers have struggled to draw a precise line between what is living and what is not, often returning to criteria such as self-organization, metabolism, and reproduction but never finding a definition that includes, and excludes, all the right things. If you say life consumes fuel to sustain itself with energy, you risk including fire; if you demand the ability to reproduce, you exclude mules. NASA hasn’t been able to do better than a working definition: “Life is a self-sustaining chemical system capable of Darwinian evolution.” It’s a decent way to describe life on Earth, but it lacks practical application. If humans found something on another planet that seemed to be alive, how much time would we have to sit around and wait for it to evolve?\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"The problem is that, in any attempt to define life, we’re inherently constrained by human intuition and the one example we have so far that informs it. The only life we know is life on Earth. Some scientists call this the n=1 problem, where \u003cem\u003en\u003c/em\u003e is the number of examples from which we can generalize. We have no idea if earthly life is average in the cosmos or some sort of freak outlier. With all the varied chemistries of other planets, all the contingencies that drive evolution, all the ways that matter and energy interact—who knows how strange life on another world might be? What if life as we know it is the wrong life to be looking for?\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"What we really want is more than a definition of life. We want to know what life, fundamentally, \u003cem\u003eis\u003c/em\u003e. For that kind of understanding, scientists turn to theories. A theory is a scientific fundamental. It not only answers questions, but frames them, opening new lines of inquiry. It explains our observations and yields predictions for future experiments to test. Consider the difference between \u003cem\u003edefining\u003c/em\u003e gravity as “the force that makes an apple fall to the ground” and \u003cem\u003eexplaining\u003c/em\u003e it, as Newton did, as the universal attraction between all particles in the universe, proportional to the product of their masses and so on. A definition tells us what we already know; a theory changes how we understand things.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"In recent years, the potential rewards of unlocking a theory of life have captivated a clutch of researchers from a diverse set of disciplines. “There are certain things in life that seem very hard to explain,” Sara Imari Walker, a physicist at Arizona State University who has been at the vanguard of this work, told me. “If you scratch under the surface, I think there is some structure that suggests formalization and mathematical laws.” It has long been presumed that although theories can explain physics and chemistry, biology is too messy, too contingent, to be boiled down to math and formulas. In 1997, the renowned biologist Ernst Mayr wrote that although the molecules that compose living organisms obey the laws of physics just as all molecules do, “organisms are fundamentally different from inert matter.” There is a threshold that matter can cross, beyond which the laws of physics do not explain or predict what happens; on the other side of that threshold is life.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"But Walker doesn’t think about life as a biologist—or an astrobiologist—does. When she talks about signs of life, she doesn’t talk about carbon, or water, or RNA, or phosphine. She reaches for different examples: a cup, a cellphone, a chair. These objects are not alive, of course, but they’re clearly products of life. In Walker’s view, this is because of their complexity. Life brings complexity into the universe, she says, in its own being and in its products, because it has memory: in DNA, in repeating molecular reactions, in the instructions for making a chair.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"Lee Cronin, a chemistry professor at the University of Glasgow and Walker’s main collaborator, told me that when Walker first explained to him her ideas for a theory of life, “I was like, ‘I have no clue what you’re talking about. But it feels like we are saying something super similar.’” Cronin studies the origin of life, also a major interest of Walker’s, and it turned out that, when expressed in math, their ideas were essentially the same. They had both zeroed in on complexity as a hallmark of life. Cronin is devising a way to systematize and measure complexity, which he calls Assembly Theory. He measures the complexity of an object—say, a molecule—by calculating the number of steps necessary to put the object’s smallest building blocks together in that certain way. His lab has found, for example, when testing a wide range of molecules, that those with an “assembly number” above 15 were exclusively the products of life. Life makes some simpler molecules, too, but only life seems to make molecules that are so complex.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"No one expects to find an alien cellphone in Mars’s Jezero Crater. But Walker’s whole notion is that it’s not only theoretically possible but genuinely achievable to identify something smaller—much smaller—that still nonetheless simply must be the result of life. The model would, in a sense, function like biosignatures as an indication of life that could be searched for. But it would drastically improve and expand the targets. Walker would use the theory to predict what life on a given planet might look like. It would require knowing a lot about the planet—information we might have about Venus, but not yet about a distant exoplanet—but, crucially, would not depend at all on how life on Earth works, what life on Earth might do with those materials. Without the ability to divorce the search for alien life from the example of life we know, Walker thinks, a search is almost pointless. “Any small fluctuations in simple chemistry can actually drive you down really radically different evolutionary pathways,” she told me. “I can’t imagine [life] inventing the same biochemistry on two worlds.”\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"\"},{\"__typename\":\"ArticleLegacyHtml\",\"tagName\":\"HR\",\"idAttr\":\"\",\"className\":\"c-section-divider\",\"style\":\"\",\"innerHtml\":\"\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"Devising a universal theory for life is an ambitious project, to say the least. The scientists I’ve spoken with who are leading the search for biosignatures tend to welcome Walker’s unconventional approach, on the grounds that the more tools available, the merrier. Even so, no one is abandoning their search in the hopes that humanity will soon solve the mystery of life. After all, finding \u003cem\u003eany\u003c/em\u003e examples of alien life—Earthlike or not, by whatever means possible—would radically advance our ability to understand the phenomenon.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"Walker’s approach is grounded in the work of, among others, the philosopher of science Carol Cleland, who wrote \u003cem\u003e\u003ca data-event-element=\\\"inline link\\\" href=\\\"https://tertulia.com/book/the-quest-for-a-universal-theory-of-life-searching-for-life-as-we-don-t-know-it-carol-e-cleland/9780521873246?affiliate_id=atl-347\\\"\u003eThe Quest for a Universal Theory of Life\u003c/a\u003e\u003c/em\u003e. But Cleland doesn’t share Walker’s ambitions that a theory may be within reach; instead she warns that any theory of life, just like a definition, cannot be constrained by the one example of life we currently know. “It’s a mistake to start theorizing on the basis of a single example, even if you’re trying hard not to be Earth-centric. Because you’re going to be Earth-centric,” Cleland told me. In other words, until we find other examples of life, we won’t have enough data from which to devise a theory. Abstracting away from Earthliness isn’t a way to be agnostic, Cleland argues. It’s a way to be too abstract.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"It’s a knot easy to get tied up in: We don’t have a theory of life to guide the search for extraterrestrials, but we need to find extraterrestrial life before we can understand life with a theory. Instead of provincially looking for life as we know it, Cleland calls for a more flexible search guided by what she calls “tentative criteria.” Such a search would have a sense of what we’re looking for, but also be open to anomalies that challenge our preconceptions, detections that aren’t life as we expected but aren’t familiar not-life either—neither a flower nor a rock. It’s unsatisfying if you want a firm answer or a quick one, but it speaks to the hope that exploration and discovery might truly expand our understanding of the cosmos and our own world.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"Cleland’s approach ends up sounding much like a lot of the work being done hunting for biosignatures today. A true discovery of phosphine in the clouds of Venus would be an anomaly for sure, and absolutely challenge preconceptions about the kinds of chemistry happening in those clouds. Other work in the field seeks similar surprises. The astrobiologist Kimberley Warren-Rhodes studies life on Earth that lives at the borders of known habitability, such as in Chile’s Atacama Desert. The point of her experiments is to better understand how life might persist—and how it might be found—on Mars. “Biology follows some rules,” she told me. The more of those rules you observe, the better sense you have of where to look on other worlds. In this light, the most immediate concern in our search for extraterrestrial life might be less that we only know about life on Earth, and more that we don’t even know that much about life on Earth in the first place. “I would say we understand about 5 percent,” Warren-Rhodes estimates of our cumulative knowledge. N=1 is a problem, and we might be at more like n=.05.\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"When I talk with people about a theory of life, which lately is my best attempt at small talk, I reach for the theory of gravity as a familiar parallel. Someone might ask, “Okay, so in terms of gravity, where are we in terms of our understanding of life? Like, Newton?” Further back, further back, I say. Walker compares us to pre-Copernican astronomers, reliant on epicycles, little orbits within orbits, to make sense of the motion we observe in the sky. Cleland has put it in terms of chemistry, in which case we’re alchemists, not even true chemists yet. We understand so little, and we think we’re ready to find other life?\"},{\"__typename\":\"ArticleParagraphContent\",\"subtype\":null,\"idAttr\":\"\",\"innerHtml\":\"Maybe we’ll never be ready. Yet how could we not search? Right now, the James Webb Space Telescope is peering into exoplanet atmospheres for spectral signatures. The Perseverance rover is bottling up soil samples on Mars for a future mission to bring to Earth to study. How could we not trawl the cosmos for anything that could help us understand our place in it, our kinship lines, and how this life, on Earth, came to be? And so we try. We scour other worlds, scan their clouds. And scratch beneath the surface, for the theory that might explain it all in equation and abstraction, to see the deeper truth beneath what we can see.\"}],\"editorialProject\":null,\"primaryCategory\":{\"__typename\":\"Channel\",\"displayName\":\"Science\",\"url\":\"https://www.theatlantic.com/science/\",\"slug\":\"science\"},\"reviews\":[],\"embeds\":[],\"preview\":null,\"tags\":[],\"layout\":\"standard\",\"secondaryByline\":\"\",\"dek\":\"We don’t really know what life is in the first place.\",\"url\":\"https://www.theatlantic.com/science/archive/2023/12/defining-life-existentialism-scientific-theory/676238/\",\"shareText\":\"If humans stumbled upon life on another planet, would we even know it was living? @jaimealyse explores an existential problem in the search for alien life:\",\"shareTitle\":\"An Existential Problem in the Search for Alien Life\",\"title\":\"An Existential Problem in the Search for Alien Life\",\"datePublished\":\"2023-12-05T12:00:00Z\",\"editorsNote\":null,\"leadArt\":{\"__typename\":\"LeadArtImage\",\"image\":{\"url\":\"https://cdn.theatlantic.com/thumbor/75t4GJf5WHxA3zYoMWFQ32Jb8Yk=/0x0:2000x1125/960x540/media/img/mt/2023/12/what_is_life_/original.jpg\",\"width\":960,\"height\":540,\"srcSet\":\"https://cdn.theatlantic.com/thumbor/BObNhpaFMEy0usHGw7ytZuDaIe8=/0x0:2000x1125/750x422/media/img/mt/2023/12/what_is_life_/original.jpg 750w, https://cdn.theatlantic.com/thumbor/_JRdcb79qt4Ad4YZTWCKDKFsrVk=/0x0:2000x1125/828x466/media/img/mt/2023/12/what_is_life_/original.jpg 828w, https://cdn.theatlantic.com/thumbor/75t4GJf5WHxA3zYoMWFQ32Jb8Yk=/0x0:2000x1125/960x540/media/img/mt/2023/12/what_is_life_/original.jpg 960w, https://cdn.theatlantic.com/thumbor/ISqFpnaRM4gIbuua4EFP1lpm-i8=/0x0:2000x1125/976x549/media/img/mt/2023/12/what_is_life_/original.jpg 976w, https://cdn.theatlantic.com/thumbor/1gMWMUEgoXt_RjV2kkhtYvIHVQA=/0x0:2000x1125/1952x1098/media/img/mt/2023/12/what_is_life_/original.jpg 1952w\",\"reducedMotionSrcSet\":null,\"altText\":\"Illustration of a flower in space\",\"captionText\":\"\",\"attributionText\":\"Ben Kothe / The Atlantic\",\"attributionUrl\":\"\",\"__typename\":\"BasicImage\"}},\"audio\":{\"url\":\"https://traffic.megaphone.fm/ATL2238832493.mp3\",\"urlAdfree\":\"https://traffic.megaphone.fm/ATL8977203559.mp3\",\"duration\":842.61,\"vendor\":\"elevenlabs\",\"type\":\"narrated\",\"__typename\":\"Audio\"},\"hasAudioRights\":true,\"narratedAudioImage\":{\"url\":\"https://cdn.theatlantic.com/thumbor/u90ma_Gyh5ZHbYOTlJLfA4RAxqs=/438x0:1563x1125/80x80/media/img/mt/2023/12/what_is_life_/original.jpg\",\"srcSet\":\"https://cdn.theatlantic.com/thumbor/u90ma_Gyh5ZHbYOTlJLfA4RAxqs=/438x0:1563x1125/80x80/media/img/mt/2023/12/what_is_life_/original.jpg 80w, https://cdn.theatlantic.com/thumbor/GzCOUn8KDUdDyPexWX_07_Jc-tQ=/438x0:1563x1125/96x96/media/img/mt/2023/12/what_is_life_/original.jpg 96w, https://cdn.theatlantic.com/thumbor/gQ5N9hOF4B9htnGRg9MnYltxRwI=/438x0:1563x1125/128x128/media/img/mt/2023/12/what_is_life_/original.jpg 128w, https://cdn.theatlantic.com/thumbor/vNzZPqC6cm6E4OhChvXNIG9uDu4=/438x0:1563x1125/160x160/media/img/mt/2023/12/what_is_life_/original.jpg 160w, https://cdn.theatlantic.com/thumbor/rK1svmQ9sNIjuARVLTd109pwpMo=/438x0:1563x1125/192x192/media/img/mt/2023/12/what_is_life_/original.jpg 192w, https://cdn.theatlantic.com/thumbor/IZU_rJp_Ef4E3CWpH6NELcpwKz0=/438x0:1563x1125/256x256/media/img/mt/2023/12/what_is_life_/original.jpg 256w, https://cdn.theatlantic.com/thumbor/KXwq6YWf-Ao3_DWt0JjiR0syZPE=/438x0:1563x1125/384x384/media/img/mt/2023/12/what_is_life_/original.jpg 384w, https://cdn.theatlantic.com/thumbor/qiRO_AOM_U9lVY_MuYeiEyqsevs=/438x0:1563x1125/512x512/media/img/mt/2023/12/what_is_life_/original.jpg 512w\",\"width\":80,\"height\":80,\"altText\":\"Illustration of a flower in space\",\"__typename\":\"BasicImage\"},\"seoTitle\":\"An Existential Problem in the Search for Alien Life\",\"hasMeter\":true,\"channels\":[{\"slug\":\"science\",\"__typename\":\"Channel\"}],\"primaryChannel\":{\"slug\":\"science\",\"__typename\":\"Channel\",\"displayName\":\"Science\"},\"shareDek\":\"We don’t really know what life is in the first place.\",\"fbiaUrl\":\"https://www.theatlantic.com/facebook-instant/article/676238/\",\"canonicalUrl\":\"https://www.theatlantic.com/science/archive/2023/12/defining-life-existentialism-scientific-theory/676238/\",\"dateModified\":\"2023-12-05T17:45:56Z\",\"syndication\":\"ALL\",\"shareImage2x1\":{\"url\":\"https://cdn.theatlantic.com/thumbor/rXrDmLpYn-O_Vd5Bj8qbzKpzLPU=/0x43:2000x1085/1200x625/media/img/mt/2023/12/what_is_life_/original.jpg\",\"height\":625,\"width\":1200,\"__typename\":\"BasicImage\"},\"shareImageGift2x1\":{\"url\":\"https://cdn.theatlantic.com/thumbor/advlFq-j2fJtwGLsk5WDgAfwlsE=/0x43:2000x1085/1200x625/filters:watermark(https://cdn.theatlantic.com/media/files/badge_2x.png,-20,20,0,33)/media/img/mt/2023/12/what_is_life_/original.jpg\",\"height\":625,\"width\":1200,\"__typename\":\"BasicImage\"},\"shareImageGiftSmall\":{\"url\":\"https://cdn.theatlantic.com/thumbor/mvJ3d7mL1q0jTY0ap0Qte6Fzhk8=/4x41:1996x1087/960x504/filters:watermark(https://cdn.theatlantic.com/media/files/badge_2x.png,-20,20,0,33)/media/img/mt/2023/12/what_is_life_/original.jpg\",\"height\":504,\"width\":960,\"__typename\":\"BasicImage\"},\"shareImageSmall\":{\"url\":\"https://cdn.theatlantic.com/thumbor/uxsx3BFdqhnfoTAAPI8dtQLA28g=/4x41:1996x1087/960x504/media/img/mt/2023/12/what_is_life_/original.jpg\",\"height\":504,\"width\":960,\"__typename\":\"BasicImage\"},\"watsonInfo\":{\"keywords\":[\"signal of life\",\"alien life\",\"Sara Imari Walker\",\"varied chemistries of other planets\",\"life\",\"extraterrestrial life\",\"high clouds of Venus\",\"product of life\",\"Earth-based telescopes\",\"small steps\",\"spectral signature of phosphine\",\"simple molecule\",\"Lee Cronin\",\"team of researchers\",\"sign of a sign of life\",\"philosopher of science Carol Cleland\",\"small talk\",\"life.But Walker\",\"working definition\",\"Signs of Life Found\",\"closest possible home\",\"much time\",\"firm answer\",\"Clouds Surrounding Venus\",\"earthly life\",\"drawing board\",\"Arizona State University\",\"self-organization\",\"theories\",\"decent way\",\"chemistry professor\",\"Walker’s unconventional approach\",\"wavelengths of light\",\"lot of room\",\"renowned biologist Ernst Mayr\",\"Walker’s view\",\"theory of life\",\"days of Aristotle\",\"object’s smallest building blocks\",\"number of examples\",\"James Webb Space Telescope\",\"search\",\"Whole Time\",\"Walker’s main collaborator\",\"right things\",\"only life\",\"kind of understanding\",\"way\",\"Darwinian evolution\",\"little orbits\"],\"__typename\":\"WatsonInfo\"},\"shareImage1x1\":{\"width\":1080,\"height\":1080,\"url\":\"https://cdn.theatlantic.com/thumbor/2nd9Jv9zx1jRkxJWzly-1GtnwTE=/438x0:1563x1125/1080x1080/media/img/mt/2023/12/what_is_life_/original.jpg\",\"__typename\":\"BasicImage\"},\"shareImage16x9\":{\"width\":1600,\"height\":900,\"url\":\"https://cdn.theatlantic.com/thumbor/Jg-QYPMiob8laaqFiGpxlmkdQ9s=/0x0:2000x1125/1600x900/media/img/mt/2023/12/what_is_life_/original.jpg\",\"__typename\":\"BasicImage\"},\"shareImage4x3\":{\"width\":1200,\"height\":900,\"url\":\"https://cdn.theatlantic.com/thumbor/onDv1TWzPr48xst4KFmlaZkSm2s=/249x0:1749x1125/1200x900/media/img/mt/2023/12/what_is_life_/original.jpg\",\"__typename\":\"BasicImage\"},\"shareImageDefault\":{\"width\":960,\"height\":540,\"url\":\"https://cdn.theatlantic.com/thumbor/75t4GJf5WHxA3zYoMWFQ32Jb8Yk=/0x0:2000x1125/960x540/media/img/mt/2023/12/what_is_life_/original.jpg\",\"__typename\":\"BasicImage\"},\"shareImageSquareDefault\":{\"width\":540,\"height\":540,\"url\":\"https://cdn.theatlantic.com/thumbor/WU05utB1gqqEV4uEWPSAcjmDPog=/438x0:1563x1125/540x540/media/img/mt/2023/12/what_is_life_/original.jpg\",\"__typename\":\"BasicImage\"},\"shareImageLeadArt\":{\"image\":{\"width\":720,\"height\":405,\"url\":\"https://cdn.theatlantic.com/thumbor/Q0l6g-fb_AhCImhUqz3s3Mog96w=/0x0:2000x1125/720x405/media/img/mt/2023/12/what_is_life_/original.jpg\",\"__typename\":\"BasicImage\"},\"__typename\":\"LeadArtImage\"},\"slug\":\"defining-life-existentialism-scientific-theory\",\"grapeshot\":{\"segments\":[\"gv_safe\",\"gb_safe\",\"pos_bofa-kwlist\",\"pos_customtopics\",\"pos_goldman_sachs\",\"pos_gucci\",\"pos_israel_conflict\",\"pos_jpmc\",\"pos_lexus_fy23\",\"pos_mastercard\",\"pos_oceangate\",\"pos_safe_core\",\"pos_safe_strict\",\"pos_safety_delta\",\"gs_science\",\"gs_science_space\",\"gs_science_misc\",\"gt_positive\",\"gs_genres\",\"gt_positive_curiosity\",\"gs_science_chemistry\",\"gs_science_biology\"],\"__typename\":\"Grapeshot\"}}}"}},"urqlClient":null},"isSocialBot":false},"page":"/[channel]/archive/[year]/[month]/[slug]/[id]","query":{"channel":"science","year":"2023","month":"12","slug":"defining-life-existentialism-scientific-theory","id":"676238"},"buildId":"e3b8da5810","assetPrefix":"https://cdn.theatlantic.com","runtimeConfig":{"GTM_CONTAINER_ID":"GTM-NTQTB9V","GTM_CONTAINER_ID_NONCONSENTED":"GTM-5839GV7","GRAPHQL_API_URL":"https://graphql.theatlantic.com","GRAPHQL_API_KEY":"JakhyMEXwa9odtB8gBxFI63ITyKqDGkn7ciGVIJf","ADS_LIB_URL":"https://www.theatlantic.com/packages/hummingbirdjs/hummingbird.min.js","ACCOUNTS_FRONTEND_URL":"https://accounts.theatlantic.com","ENABLE_FEATURE_ARTICLE_RENDER":"false","RECAPTCHA_SITE_KEY":"6Lc9Z7AUAAAAAEYS1dgAG2_6tT3KLqZQ1z4kbDRc","BETA_ENV":false},"isFallback":false,"isExperimentalCompile":false,"dynamicIds":[9587,50649],"gip":true,"appGip":true,"scriptLoader":[]}</script><script nomodule="" src="https://cdn.theatlantic.com/_next/static/chunks/polyfills-c67a75d1b6f99dc8.js"></script><script async="" src="https://cdn.theatlantic.com/_next/static/chunks/9587.e62a84643012a04f.js"></script><script async="" src="https://cdn.theatlantic.com/_next/static/chunks/649.81412a92c899897e.js"></script><script src="https://cdn.theatlantic.com/_next/static/chunks/webpack-2462136f7fddc57d.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/framework-ca706bf673a13738.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/main-7cf71189bb4b30b4.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/pages/_app-ff1d27643a500c40.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/6729-7978443139836095.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/5303-a81934d6e8e761ae.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/9843-3905ec2636af2c3c.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/899-30da5ef51c1b6fdb.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/2912-ebf029ed4116b01f.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/4747-71d47472f5c4beea.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/6392-1397c4f8500d73b6.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/4947-02b1b9c56798b167.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/3297-031e2fc5be155f31.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/365-e835216503d223da.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/1124-b1cf3a9d4ae92dcb.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/9310-d0d5baafd7a7f3b8.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/5169-3adfae2cce1eb773.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/6346-ef3edb895c92109b.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/663-0fc7e1b7a52e2587.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/2544-aaa838d354b1cbbb.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/chunks/pages/%5Bchannel%5D/archive/%5Byear%5D/%5Bmonth%5D/%5Bslug%5D/%5Bid%5D-0fee4688858b18b9.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/e3b8da5810/_buildManifest.js" async=""></script><script src="https://cdn.theatlantic.com/_next/static/e3b8da5810/_ssgManifest.js" async=""></script></body></html>