Luis Walter Alvarez | Scientists and Research

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This module traces Alvarez’s application of physics to aircraft safety, Egyptian pyramids, K-electron capture, nuclear bombs, and the hydrogen bubble chamber which led to the discovery of many new subatomic particles."> <meta name="keywords" content="Luis Alvarez, Luis Walter Alvarez, Alvarez, atomic particles, K-electrons, cosmic rays, dinosaurs, extinction"> <meta name="viewport" content="width=device-width, initial-scale=1.0, shrink-to-fit=no"> <meta name="msvalidate.01" content="D8E20F39AD48052260032E56DE409970"> <script type="application/ld+json"> { "@context": "http://schema.org/", "@type": "Article", "mainEntityOfPage": { "@type": "WebPage", "@id": "https://visionlearning.com/en/library/scientists-and-research/58/luis-walter-alvarez/229" }, "name": "Luis Walter Alvarez", "headline": "Luis Walter Alvarez: Uncovering secrets of the atom and life on earth", "author": { "@type": "Person", "name": "David Warmflash, MD" }, "datePublished": "2016-04-29 03:27:57", "dateModified": "2017-02-12T08:30:00+05:00", "image": { "@type": "ImageObject", "url": "/img/library/moduleImages/featured_image_229-23061210064453.jpeg", "width": 696, "height": 464 }, "publisher": { "@type": "Organization", "name": "Visionlearning, Inc.", "logo": { "@type": "ImageObject", "url": "http://visionlearning.com/images/logo.png", "width": 278, "height": 60 } }, "description": "Luis Alvarez is less famous for his Nobel prize-winning research into subatomic particles than for his theory on how dinosaurs became extinct. Yet, before he started looking into dinosaurs, Alvarez was credited with a lifetime of major advances in atomic physics. This module traces Alvarez’s application of physics to aircraft safety, Egyptian pyramids, K-electron capture, nuclear bombs, and the hydrogen bubble chamber which led to the discovery of many new subatomic particles.", "keywords": "Luis Alvarez, Luis Walter Alvarez, Alvarez, atomic particles, K-electrons, cosmic rays, dinosaurs, extinction", "inLanguage": { "@type": "Language", "name": "English", "alternateName": "en" }, "copyrightHolder": { "@type": "Organization", "name": "Visionlearning, Inc." }, "copyrightYear": "2016"} </script> <meta property="og:url" content="https://visionlearning.com/en/library/scientists-and-research/58/luis-walter-alvarez/229"> <meta property="og:title" content="Luis Walter Alvarez | Scientists and Research | Visionlearning" /> <meta property="og:type" content="website"> <meta property="og:site_name" content="Visionlearning"> <meta property="og:description" content="Luis Alvarez is less famous for his Nobel prize-winning research into subatomic particles than for his theory on how dinosaurs became extinct. Yet, before he started looking into dinosaurs, Alvarez was credited with a lifetime of major advances in atomic physics. This module traces Alvarez’s application of physics to aircraft safety, Egyptian pyramids, K-electron capture, nuclear bombs, and the hydrogen bubble chamber which led to the discovery of many new subatomic particles."> <meta property="og:image" content="https://visionlearning.com/images/logo.png"> <meta property="fb:admins" content="100000299664514"> <link rel="stylesheet" type="text/css" href="/css/visionlearning.css">  <link rel="stylesheet" type="text/css" href="/css/visionlearning-icons.css">  <link rel="preload" href="https://fonts.gstatic.com"> <link rel="preload" href="https://fonts.googleapis.com/css2?family=Open+Sans:ital,wght@0,400;0,700;1,400;1,700&family=Schoolbell&display=swap"> <style> textarea.myEditor { width: 90%; height: 350px; } </style> <script type="text/x-mathjax-config" src="/js/mathjax-config.js"></script> <script id="MathJax-script" async src="/js/mathjax/tex-svg.js"></script> <script async 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<li><a href="/en/library/earth-science/6/factors-that-control-earths-temperature/234">Factors that Control Earth's Temperature</a></li> <li><a href="/en/library/earth-science/6/circulation-in-the-atmosphere/255">Circulation in the Atmosphere</a></li> </ul> </div> <button class="accordion__button" id="acc-button-hazards" data-accordion="button" aria-controls="acc-panel-hazards" aria-expanded="false"> <span class="accordion__button__label"> Hazards </span> </button> <div class="accordion__panel" id="acc-panel-hazards" data-accordion="panel" aria-labelledby="acc-button-hazards" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/natural-hazards-and-risk/288">Natural Hazards and Risk</a></li> </ul> </div> <button class="accordion__button" id="acc-button-earth-history" data-accordion="button" aria-controls="acc-panel-earth-history" aria-expanded="false"> <span class="accordion__button__label"> Earth History </span> </button> <div class="accordion__panel" 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class="accordion__panel" id="acc-panel-ecology" data-accordion="panel" aria-labelledby="acc-button-ecology" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/biodiversity-i/276">Biodiversity I</a></li> <li><a href="/en/library/environmental-science/61/biodiversity-ii/281">Biodiversity II</a></li> <li><a href="/en/library/environmental-science/61/ecosystem-services/279">Ecosystem Services</a></li> <li><a href="/en/library/environmental-science/61/population-biology/287">Population Biology</a></li> </ul> </div> <button class="accordion__button" id="acc-button-earth-cycles" data-accordion="button" aria-controls="acc-panel-earth-cycles" aria-expanded="false"> <span class="accordion__button__label"> Earth Cycles </span> </button> <div class="accordion__panel" id="acc-panel-earth-cycles" data-accordion="panel" aria-labelledby="acc-button-earth-cycles" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/the-nitrogen-cycle/98">The Nitrogen Cycle</a></li> <li><a href="/en/library/environmental-science/61/the-carbon-cycle/95">The Carbon Cycle</a></li> <li><a href="/en/library/environmental-science/61/the-phosphorus-cycle/197">The Phosphorus Cycle</a></li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-research" data-accordion="button" aria-controls="acc-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/environmental-science/61/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-general-science" data-accordion="button" aria-controls="acc-panel-general-science" aria-expanded="false"> <span class="accordion__button__label"> General Science </span> </button> <div class="accordion__panel" id="acc-panel-general-science" data-accordion="panel" aria-labelledby="acc-button-general-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-methods" data-accordion="button" aria-controls="acc-panel-methods" aria-expanded="false"> <span class="accordion__button__label"> Methods </span> </button> <div class="accordion__panel" id="acc-panel-methods" data-accordion="panel" aria-labelledby="acc-button-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-scientific-method/45">The Scientific Method</a></li> </ul> </div> <button class="accordion__button" id="acc-button-measurement" data-accordion="button" aria-controls="acc-panel-measurement" aria-expanded="false"> <span class="accordion__button__label"> Measurement </span> </button> <div class="accordion__panel" id="acc-panel-measurement" data-accordion="panel" aria-labelledby="acc-button-measurement" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-metric-system/47">The Metric System</a></li> </ul> </div> <button class="accordion__button" id="acc-button-physical-properties" data-accordion="button" aria-controls="acc-panel-physical-properties" aria-expanded="false"> <span class="accordion__button__label"> Physical Properties </span> </button> <div class="accordion__panel" id="acc-panel-physical-properties" data-accordion="panel" aria-labelledby="acc-button-physical-properties" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/temperature/48">Temperature</a></li> <li><a href="/en/library/general-science/3/density-and-buoyancy/37">Density and Buoyancy</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-math-in-science" data-accordion="button" aria-controls="acc-panel-math-in-science" aria-expanded="false"> <span class="accordion__button__label"> Math in Science </span> </button> <div class="accordion__panel" id="acc-panel-math-in-science" data-accordion="panel" aria-labelledby="acc-button-math-in-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-equations" data-accordion="button" aria-controls="acc-panel-equations" aria-expanded="false"> <span class="accordion__button__label"> Equations </span> </button> <div class="accordion__panel" id="acc-panel-equations" data-accordion="panel" aria-labelledby="acc-button-equations" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/unit-conversion/144">Unit Conversion</a></li> <li><a href="/en/library/math-in-science/62/linear-equations/194">Linear Equations</a></li> <li><a href="/en/library/math-in-science/62/exponential-equations-i/206">Exponential Equations I</a></li> <li><a href="/en/library/math-in-science/62/exponential-equations-ii/210">Exponential Equations II</a></li> <li><a href="/en/library/math-in-science/62/scientific-notation/250">Scientific Notation</a></li> <li><a href="/en/library/math-in-science/62/measurement/257">Measurement</a></li> </ul> </div> <button class="accordion__button" id="acc-button-statistics" data-accordion="button" aria-controls="acc-panel-statistics" aria-expanded="false"> <span class="accordion__button__label"> Statistics </span> </button> <div class="accordion__panel" id="acc-panel-statistics" data-accordion="panel" aria-labelledby="acc-button-statistics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/introduction-to-descriptive-statistics/218">Introduction to Descriptive Statistics</a></li> <li><a href="/en/library/math-in-science/62/introduction-to-inferential-statistics/224">Introduction to Inferential Statistics</a></li> <li><a href="/en/library/math-in-science/62/statistical-techniques/239">Statistical Techniques</a></li> </ul> </div> <button class="accordion__button" id="acc-button-trigonometric-functions" data-accordion="button" aria-controls="acc-panel-trigonometric-functions" aria-expanded="false"> <span class="accordion__button__label"> Trigonometric Functions </span> </button> <div class="accordion__panel" id="acc-panel-trigonometric-functions" data-accordion="panel" aria-labelledby="acc-button-trigonometric-functions" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/wave-mathematics/131">Wave Mathematics</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-physics" data-accordion="button" aria-controls="acc-panel-physics" aria-expanded="false"> <span class="accordion__button__label"> Physics </span> </button> <div class="accordion__panel" id="acc-panel-physics" data-accordion="panel" aria-labelledby="acc-button-physics" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-light-and-optics" data-accordion="button" aria-controls="acc-panel-light-and-optics" aria-expanded="false"> <span class="accordion__button__label"> Light and Optics </span> </button> <div class="accordion__panel" id="acc-panel-light-and-optics" data-accordion="panel" aria-labelledby="acc-button-light-and-optics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/physics/24/the-nature-of-light/132">The Nature of Light</a></li> <li><a href="/en/library/physics/24/electromagnetism-and-light/138">Electromagnetism and Light</a></li> </ul> </div> <button class="accordion__button" 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data-accordion="panel" aria-labelledby="acc-button-process-of-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-introduction" data-accordion="button" aria-controls="acc-panel-introduction" aria-expanded="false"> <span class="accordion__button__label"> Introduction </span> </button> <div class="accordion__panel" id="acc-panel-introduction" data-accordion="panel" aria-labelledby="acc-button-introduction" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-process-of-science/176">The Process of Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-the-culture-of-science" data-accordion="button" aria-controls="acc-panel-the-culture-of-science" aria-expanded="false"> <span class="accordion__button__label"> The Culture of Science </span> </button> <div class="accordion__panel" id="acc-panel-the-culture-of-science" data-accordion="panel" aria-labelledby="acc-button-the-culture-of-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-nature-of-scientific-knowledge/185">The Nature of Scientific Knowledge</a></li> <li><a href="/en/library/process-of-science/49/scientists-and-the-scientific-community/172">Scientists and the Scientific Community</a></li> <li><a href="/en/library/process-of-science/49/scientific-ethics/161">Scientific Ethics</a></li> <li><a href="/en/library/process-of-science/49/scientific-institutions-and-societies/162">Scientific Institutions and Societies</a></li> </ul> </div> <button class="accordion__button" id="acc-button-ideas-in-science" data-accordion="button" aria-controls="acc-panel-ideas-in-science" aria-expanded="false"> <span class="accordion__button__label"> Ideas in Science </span> </button> <div class="accordion__panel" id="acc-panel-ideas-in-science" data-accordion="panel" aria-labelledby="acc-button-ideas-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/theories-hypotheses-and-laws/177">Theories, Hypotheses, and Laws</a></li> <li><a href="/en/library/process-of-science/49/scientific-controversy/181">Scientific Controversy</a></li> <li><a href="/en/library/process-of-science/49/creativity-in-science/182">Creativity in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-research-methods" data-accordion="button" aria-controls="acc-panel-research-methods" aria-expanded="false"> <span class="accordion__button__label"> Research Methods </span> </button> <div class="accordion__panel" id="acc-panel-research-methods" data-accordion="panel" aria-labelledby="acc-button-research-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-practice-of-science/148">The Practice of Science</a></li> <li><a href="/en/library/process-of-science/49/experimentation-in-scientific-research/150">Experimentation in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/description-in-scientific-research/151">Description in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/comparison-in-scientific-research/152">Comparison in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/modeling-in-scientific-research/153">Modeling in Scientific Research</a></li> </ul> </div> <button class="accordion__button" id="acc-button-data" data-accordion="button" aria-controls="acc-panel-data" aria-expanded="false"> <span class="accordion__button__label"> Data </span> </button> <div class="accordion__panel" id="acc-panel-data" data-accordion="panel" aria-labelledby="acc-button-data" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/data-analysis-and-interpretation/154">Data Analysis and Interpretation</a></li> <li><a href="/en/library/process-of-science/49/uncertainty-error-and-confidence/157">Uncertainty, Error, and Confidence</a></li> <li><a href="/en/library/process-of-science/49/statistics-in-science/155">Statistics in Science</a></li> <li><a href="/en/library/process-of-science/49/using-graphs-and-visual-data-in-science/156">Using Graphs and Visual Data in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-communication" data-accordion="button" aria-controls="acc-panel-scientific-communication" aria-expanded="false"> <span class="accordion__button__label"> Scientific Communication </span> </button> <div class="accordion__panel" id="acc-panel-scientific-communication" data-accordion="panel" aria-labelledby="acc-button-scientific-communication" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/understanding-scientific-journals-and-articles/158">Understanding Scientific Journals and Articles</a></li> <li><a href="/en/library/process-of-science/49/utilizing-the-scientific-literature/173">Utilizing the Scientific Literature</a></li> <li><a href="/en/library/process-of-science/49/peer-review-in-scientific-publishing/159">Peer Review in Scientific Publishing</a></li> <li><a href="/en/library/process-of-science/49/the-how-and-why-of-scientific-meetings/186">The How and Why of Scientific Meetings</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-scientists-and-research" data-accordion="button" aria-controls="acc-panel-scientists-and-research" aria-expanded="false"> <span class="accordion__button__label"> Scientists and Research </span> </button> <div class="accordion__panel" id="acc-panel-scientists-and-research" data-accordion="panel" aria-labelledby="acc-button-scientists-and-research" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-scientific-research" data-accordion="button" aria-controls="acc-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/scientists-and-research/58/from-stable-chromosomes-to-jumping-genes/184">From Stable Chromosomes to Jumping Genes</a></li> <li><a href="/en/library/scientists-and-research/58/an-elegant-experiment-to-test-the-process-of-dna-replication/187">An Elegant Experiment to Test the Process of DNA Replication</a></li> <li><a href="/en/library/scientists-and-research/58/the-founding-of-neuroscience/233">The Founding of Neuroscience</a></li> <li><a href="/en/library/scientists-and-research/58/tracking-endangered-jaguars-across-the-border/189">Tracking Endangered Jaguars across the Border</a></li> <li><a href="/en/library/scientists-and-research/58/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> <li><a href="/en/library/scientists-and-research/58/revolutionizing-medicine-with-monoclonal-antibodies/220">Revolutionizing Medicine with Monoclonal Antibodies</a></li> <li><a href="/en/library/scientists-and-research/58/uncovering-the-mysteries-of-chronic-mountain-sickness/238">Uncovering the Mysteries of Chronic Mountain Sickness</a></li> </ul> </div> <button class="accordion__button" id="acc-button-profiles-in-science" data-accordion="button" aria-controls="acc-panel-profiles-in-science" aria-expanded="false"> <span class="accordion__button__label"> Profiles in Science </span> </button> <div class="accordion__panel" id="acc-panel-profiles-in-science" data-accordion="panel" aria-labelledby="acc-button-profiles-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/luis-e.-miramontes/232">Luis E. Miramontes</a></li> <li><a href="/en/library/scientists-and-research/58/bernardo-houssay/237">Bernardo Houssay</a></li> <li><a href="/en/library/scientists-and-research/58/craig-lee/256">Craig Lee</a></li> <li><a href="/en/library/scientists-and-research/58/david-ho/241">David Ho</a></li> <li><a href="/en/library/scientists-and-research/58/louis-tompkins-wright/244">Louis Tompkins Wright</a></li> <li><a href="/en/library/scientists-and-research/58/carlos-j.-finlay/217">Carlos J. Finlay</a></li> <li><a href="/en/library/scientists-and-research/58/cecilia-payne/290">Cecilia Payne</a></li> <li><a href="/en/library/scientists-and-research/58/jazmin-scarlett/291">Jazmin Scarlett</a></li> <li><a href="/en/library/scientists-and-research/58/ramari-stewart/292">Ramari Stewart</a></li> <li><a href="/en/library/scientists-and-research/58/johnson-cerda/300">Johnson Cerda</a></li> <li><a href="/en/library/scientists-and-research/58/ellen-ochoa/201">Ellen Ochoa</a></li> <li><a href="/en/library/scientists-and-research/58/ruth-benerito/205">Ruth Benerito</a></li> <li><a href="/en/library/scientists-and-research/58/franklin-chang-díaz/219">Franklin Chang Díaz</a></li> <li><a href="/en/library/scientists-and-research/58/percy-lavon-julian/221">Percy Lavon Julian</a></li> <li class="current">Luis Walter Alvarez</li> <li><a href="/en/library/scientists-and-research/58/france-anne-dominic-córdova/230">France Anne-Dominic Córdova</a></li> </ul> </div> </div> </div> </div> </div> </li> <li>  <button class="button" data-toggle="dropdown">Scientists and Research </button> <div class="nav__dropdown box-shadow-1 padding-1"> <div class="accordion accordion--secondary font-size-sm"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-sub-button-scientific-research" data-accordion="button" aria-controls="acc-sub-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-sub-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-sub-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/scientists-and-research/58/from-stable-chromosomes-to-jumping-genes/184">From Stable Chromosomes to Jumping Genes</a></li> <li><a href="/en/library/scientists-and-research/58/an-elegant-experiment-to-test-the-process-of-dna-replication/187">An Elegant Experiment to Test the Process of DNA Replication</a></li> <li><a href="/en/library/scientists-and-research/58/the-founding-of-neuroscience/233">The Founding of Neuroscience</a></li> <li><a href="/en/library/scientists-and-research/58/tracking-endangered-jaguars-across-the-border/189">Tracking Endangered Jaguars across the Border</a></li> <li><a href="/en/library/scientists-and-research/58/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> <li><a href="/en/library/scientists-and-research/58/revolutionizing-medicine-with-monoclonal-antibodies/220">Revolutionizing Medicine with Monoclonal Antibodies</a></li> <li><a href="/en/library/scientists-and-research/58/uncovering-the-mysteries-of-chronic-mountain-sickness/238">Uncovering the Mysteries of Chronic Mountain Sickness</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-profiles-in-science" data-accordion="button" aria-controls="acc-sub-panel-profiles-in-science" aria-expanded="false"> <span class="accordion__button__label"> Profiles in Science </span> </button> <div class="accordion__panel" id="acc-sub-panel-profiles-in-science" data-accordion="panel" aria-labelledby="acc-sub-button-profiles-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/luis-e.-miramontes/232">Luis E. Miramontes</a></li> <li><a href="/en/library/scientists-and-research/58/bernardo-houssay/237">Bernardo Houssay</a></li> <li><a href="/en/library/scientists-and-research/58/craig-lee/256">Craig Lee</a></li> <li><a href="/en/library/scientists-and-research/58/david-ho/241">David Ho</a></li> <li><a href="/en/library/scientists-and-research/58/louis-tompkins-wright/244">Louis Tompkins Wright</a></li> <li><a href="/en/library/scientists-and-research/58/carlos-j.-finlay/217">Carlos J. Finlay</a></li> <li><a href="/en/library/scientists-and-research/58/cecilia-payne/290">Cecilia Payne</a></li> <li><a href="/en/library/scientists-and-research/58/jazmin-scarlett/291">Jazmin Scarlett</a></li> <li><a href="/en/library/scientists-and-research/58/ramari-stewart/292">Ramari Stewart</a></li> <li><a href="/en/library/scientists-and-research/58/johnson-cerda/300">Johnson Cerda</a></li> <li><a href="/en/library/scientists-and-research/58/ellen-ochoa/201">Ellen Ochoa</a></li> <li><a href="/en/library/scientists-and-research/58/ruth-benerito/205">Ruth Benerito</a></li> <li><a href="/en/library/scientists-and-research/58/franklin-chang-díaz/219">Franklin Chang Díaz</a></li> <li><a href="/en/library/scientists-and-research/58/percy-lavon-julian/221">Percy Lavon Julian</a></li> <li class="current">Luis Walter Alvarez</li> <li><a href="/en/library/scientists-and-research/58/france-anne-dominic-córdova/230">France Anne-Dominic Córdova</a></li> </ul> </div> </div> </div> </div> </li> </ul> </nav>  <div id="theTop"></div> <main id="skip-header-content"> <div class="margin-bottom-5"> <article class="container wide module"> <header class="grid grid--sidebar-right module__header"> <div class="module__header__title"> <span class="subcategory"> <strong><em>Profiles in Science</em></strong> </span> <h1>Luis Walter Alvarez: <sub><em>Uncovering secrets of the atom and life on earth</em></sub></h1> <p class="byline">by David Warmflash, MD</p> <nav class="module__header__tabs"> <ul class="tabs-nav tabs-nav--horizontal library"> <li> <a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229/reading" aria-current="page" >Reading</a> </li> <li> <a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229/quiz">Quiz</a> </li> <li> <a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229/resources">Teach with this</a> </li> </ul> </nav> </div> </header> <hr class="divider"/>   <div class="grid grid--sidebar-right grid--divider"> <div class="order-2 order-1--lg module__main"> <div class="narrow margin-x-auto margin-y-5"> <div class="accordion margin-bottom-5">  <button class="accordion__button" id="acc-button-key-concepts" data-accordion="button" aria-controls="acc-panel-key-concepts" aria-expanded="true" tabindex="0"> Did you know? </button> <div class="accordion__panel shown show" id="acc-panel-key-concepts" data-accordion="panel" aria-labelledby="acc-button-key-concepts" role="region"> <div class="accordion__panel__content"> <p>Did you know that the scientist who is famous for his theory of how dinosaurs became extinct was not even a paleontologist? Rather, Luis Alvarez was a Nobel Prize-winning physicist who explored dinosaur extinction only because his son was interested in it. Among his accomplishments, Alvarez discovered several subatomic particles, invented a radar system for safer aircraft landing, applied cosmic ray physics to the study of Egyptian pyramids, and developed a way to detonate atomic bombs during World War II.</p> </div> </div>  <button class="accordion__button" id="acc-button-terms-you-should-know" data-accordion="button" aria-controls="acc-panel-terms-you-should-know" aria-expanded="false" tabindex="0"> Terms you should know </button> <div class="accordion__panel" id="acc-panel-terms-you-should-know" data-accordion="panel" aria-labelledby="acc-button-terms-you-should-know" role="region" aria-hidden="true"> <div class="accordion__panel__content"> <dl> <dt>cosmic rays </dt> <dd> high-energy radiation particles that bombard Earth from outside of Earth’s atmosphere. </dd> <dt>particle physics </dt> <dd> the branch of physics that studies the most basic elements that make up matter and the physical universe. </dd> <dt>subatomic particles </dt> <dd> particles that are smaller than an atom, such as protons, neutrons, electrons, positrons, and K mesons, among others.</dd> </dl> </div> </div> </div> <hr class="border-color-dark" /> <section> <div class="container narrow"> <p>Fermi, Oppenheimer, Szilárd, Lawrence, Rabi – these scientists are all famous in the history of America’s nuclear program, but hardly ever is the name Luis Alvarez listed among them in popular culture. Possibly, this is because his work, and fame, expanded into so many other fields – even into the realm of what killed the dinosaurs.</p> <p>In 1968, Alvarez received the <mark class="term" data-term="Nobel Prize" data-term-def="Awards made annually, beginning in 1901, from funds originally established by Alfred B. Nobel for outstanding achievement in physics, chemistry, medicine&hellip;" data-term-url="/en/glossary/view/Nobel+Prize/3843">Nobel Prize</mark> in Physics for discovering numerous subatomic <mark class="term" data-term="particle" data-term-def="A tiny piece of matter." data-term-url="/en/glossary/view/particle/8259">particles</mark> through what physics calls “resonance states” and for developing a device and a <mark class="term" data-term="method" data-term-def="A procedure or process; a systematic way of performing a task or conducting research." data-term-url="/en/glossary/view/method/8238">method</mark> to make the discoveries possible. His work facilitated America’s budding nuclear technology in World War II and also changed the way that physicists viewed <mark class="term" data-term="matter" data-term-def="The substance that makes up physical objects." data-term-url="/en/glossary/view/matter/8264">matter</mark> and the <mark class="term" data-term="universe" data-term-def="The cosmos and everything that exists in it." data-term-url="/en/glossary/view/universe/5288">universe</mark>. He created technology to help aircraft approach and land at airports more safely and applied the physics of cosmic rays to help archaeologists study Egyptian pyramids. All of this happened over a career lasting half a century, and yet Alvarez is probably best remembered for answering the dinosaur question right at the end of his career.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_9648.jpg"> <img src="/img/library/modules/mid229/Image/VLObject-9648-160428100447.jpg" alt="Figure 1: Luis Walter Alvarez (1961)." /> </button> <figcaption> <p><strong>Figure 1</strong>: Luis Walter Alvarez (1961).</p> <span class="credit">image ©Dutch National Archives</span> </figcaption> </figure> </div> <p><section id="toc_1" class=""> <h2>Born into a family of medicine</h2></p> <p>Luis Walter Alvarez was born in San Francisco, California, on June 13, 1911. Both his father and <mark class="term" data-term="paternal" data-term-def="Derived from or related to one's father." data-term-url="/en/glossary/view/paternal/8364">paternal</mark> grandfather were physicians, which made science a frequent topic in the Alvarez home. Though medicine beckoned as a logical career choice, Alvarez was more interested in pure science. Thus, in 1928, he enrolled at the University of Chicago with a major in chemistry. He was only a B student, until he switched his major to physics, which interested him much more. After receiving his BS in 1932, he continued at the University of Chicago as a graduate student.</p><p>His graduate school mentor was none other than Arthur Compton, a Nobel Prize-winning physicist. Compton is also remembered as a leader in work on “Chicago Pile One (CP-1)”, the first nuclear reactor that was a cornerstone of the atomic weapons <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark> program (Figure 2). The weapons research peaked during the 1940s, when Alvarez also was part of the team. Both men were destined to work on nuclear development, because that’s what the most talented physicists of the time would be summoned to during the war. </p><p>This included not just Alvarez and Compton, but various scientists from the University of Chicago, which had one of the best physics departments. During the early 1930s, however, Compton’s focus was on cosmic rays, and so this is the phenomenon that Alvarez studied as a graduate student (Figure 2). Working in Compton’s lab, he built an array of Geiger counters to study cosmic rays. In 1933, this work led to a joint publication in the journal <em>Physical Review</em> in which Alvarez and Compton showed that cosmic rays were positively charged <mark class="term" data-term="particle" data-term-def="A tiny piece of matter." data-term-url="/en/glossary/view/particle/8259">particles</mark>.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_9649.jpg"> <img src="/img/library/modules/mid229/Image/VLObject-9649-160428110403.jpg" alt="Figure 2: Alvarez as a graduate student in 1933 working on cosmic ray programs for his Ph.D. thesis with Arthur Compton." /> </button> <figcaption> <p><strong>Figure 2</strong>: Alvarez as a graduate student in 1933 working on cosmic ray programs for his Ph.D. thesis with Arthur Compton.</p> <span class="credit">image ©2010 The Regents of the University of California, through the Lawrence Berkeley National Laboratory.</span> </figcaption> </figure> </div> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc9610"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">In the 1930s and 40s, the most talented physicists worked on</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-9610-0-option-a" name="quiz-option-9610" type="radio" value="nuclear weapons." > <span class="option__label"> <span class="screen-reader-only">a.</span> nuclear weapons. </span> </label> <span class="quiz__response" id="response-9610-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-9610-1-option-b" name="quiz-option-9610" type="radio" value="tools for archeology." > <span class="option__label"> <span class="screen-reader-only">b.</span> tools for archeology. </span> </label> <span class="quiz__response" id="response-9610-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_2"> <h2>Back to the Bay Area to start his career</h2><p>Alvarez received his Ph.D. in 1936 and returned to the San Francisco Bay area to work as an experimental physicist in the <mark class="term" data-term="radiation" data-term-def="Energy emitted as particles, waves, or rays." data-term-url="/en/glossary/view/radiation/8266">Radiation</mark> Laboratory at the University of California Berkeley. Along with his alma mater, Berkeley was a focal point of America’s budding nuclear <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark> that would come to be called the <mark class="term" data-term="Manhattan Project" data-term-def="A United States project initiated in August 1942 that was responsible for developing atomic technology, and specifically an atomic bomb, during&hellip;" data-term-url="/en/glossary/view/Manhattan+Project/4762">Manhattan Project</mark>. During his first few years at the Berkeley lab, Alvarez devised instruments and <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> aimed at understanding the phenomenon of K-electron capture. Through this mechanism, an <mark class="term" data-term="electron" data-term-def="A subatomic particle with a negative charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 9.11 × 10<sup>-31</sup> kg. Electrons&hellip;" data-term-url="/en/glossary/view/electron/852">electron</mark> captured by an <mark class="term" data-term="atom" data-term-def="The smallest unit of an element that retains the chemical properties of the element. Atoms can exist alone or in&hellip;" data-term-url="/en/glossary/view/atom/1509">atom</mark> combines with one of the <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">protons</mark> in the atom’s <mark class="term" data-term="nucleus" data-term-def="1. [Atomic] A tiny, dense positively charged mass at the heart of an atom. The nucleus is composed of protons and&hellip;" data-term-url="/en/glossary/view/nucleus/1526">nucleus</mark>. This transforms the proton into a <mark class="term" data-term="neutron" data-term-def="A sub-atomic particle with no charge and a mass of 1.675 × 10<sup>-27</sup> kg. Neutrons are found in the nucleus&hellip;" data-term-url="/en/glossary/view/neutron/1520">neutron</mark>, thereby transmuting the atom into a different chemical <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">element</mark>. Theoretical physics predicted K-electron capture, but Alvarez’s instruments and experimental design allowed the Berkeley scientists to observe the <mark class="term" data-term="process" data-term-def="Method, procedure; series of actions or steps." data-term-url="/en/glossary/view/process/8256">process</mark> directly in 1937. Around the same time, Alvarez also used a device called a cyclotron to prove the stability of helium-3. This and his K-electron capture research contributed to a growing understanding of atomic physics just as it was becoming clear that Europe was on the pathway to war.</p><p>Having taken up flying as a graduate student, Alvarez had an interest in applying his physics knowledge to aircraft safety. By the early 1940s, the US was entering World War II. As one of the nation’s top young physicists, Alvarez was assigned to a new laboratory set up at the Massachusetts Institute of Technology. Alvarez’s role at the new MIT lab was to work on microwave <mark class="term" data-term="radar" data-term-def="a system for detecting the presence of objects, like raindrops, by sending out pulses of high-frequency electromagnetic waves that are reflected&hellip;" data-term-url="/en/glossary/view/radar/12931">radar</mark> <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">systems</mark>. This led him to invent a new radar system that gave ground controllers extreme <mark class="term" data-term="precision" data-term-def="In science, precision refers to the degree of specified detail which can be expressed in a value. For example, a value&hellip;" data-term-url="/en/glossary/view/precision/4223">precision</mark> for monitoring positions of aircraft and for directing them to approach and land on runways. This allowed aircraft to land safely in foggy conditions and more easily at night. Along with civilian aviation authorities, the military took interest in this <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark>. Given Alvarez’s talent in numerous areas of physics, however, the government was particularly interested in recruiting him for the <mark class="term" data-term="Manhattan Project" data-term-def="A United States project initiated in August 1942 that was responsible for developing atomic technology, and specifically an atomic bomb, during&hellip;" data-term-url="/en/glossary/view/Manhattan+Project/4762">Manhattan Project</mark>, so his stay in the Boston area would be cut short.</p></section> <section id="toc2_1"><h3>Top-secret nuclear science</h3><p>In 1943, Alvarez was invited to work secretly on nuclear issues and like most other scientists on the team was not given the details of the overall project. All he knew at first was that he would be working on ways to detect whether Germany was developing its own atomic bomb. Because <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark> to develop nuclear weapons releases xenon-133 and other radioactive gases, Alvarez was confident that he could develop a detection strategy, so he agreed to work with the government. In 1944, he packed his bags and set out for Los Alamos, New Mexico.</p><p>Using special airborne equipment and techniques whose development Alvarez spearheaded, US flight crews eventually determined that German scientists were not on a pathway to a nuclear bomb, or at least they were not very close. On June 6, 1944, the invasion of Normandy set the Allies on course for ending the war in Europe within a year, but the <mark class="term" data-term="Manhattan Project" data-term-def="A United States project initiated in August 1942 that was responsible for developing atomic technology, and specifically an atomic bomb, during&hellip;" data-term-url="/en/glossary/view/Manhattan+Project/4762">Manhattan Project</mark> continued, based on the idea that the bomb might be needed to defeat Japan. It was under this scenario that Alvarez’s focus shifted from the problem of nuclear detection to detonation of an actual weapon.</p><p>Two explosive nuclear fuels were being created at an excruciatingly slow rate: uranium and plutonium. Each fuel required a different kind of detonation <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">system</mark> and the US military wanted both kinds of bombs in order to have more bombs sooner. Alvarez was a key researcher in the development of electrical detonation systems for the plutonium fuel, which was used in two explosions during the war. The first, called the Trinity Test, took place July 16, 1945, at the White Sands Proving Ground in New Mexico. In this test, a plutonium bomb was exploded at the top of a 30-meter tower to see whether it would function but also to simulate a bomb dropped from an aircraft exploding prior to hitting the ground. As expected, the test showed that explosion above the ground maximized the amount of destructive <mark class="term" data-term="energy" data-term-def="An abstract property defined as the capacity to do work. The basic forms of energy include chemical, electrical, mechanical, nuclear, and&hellip;" data-term-url="/en/glossary/view/energy/1497">energy</mark> yet minimized the amount of nuclear fallout (Figure 3).</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_9650.jpg"> <img src="/img/library/modules/mid229/Image/VLObject-9650-160429120403.jpg" alt="Figure 3: The Trinity Test explosion in 1945." /> </button> <figcaption> <p><strong>Figure 3</strong>: The Trinity Test explosion in 1945.</p> <span class="credit">image ©Department of Energy</span> </figcaption> </figure> </div> <p>The second plutonium explosion, which also depended on the Alvarez detonation equipment, was the bomb codenamed “Fat Man” – the weapon that destroyed the city of Nagasaki on August 9, 1945. Three days earlier, the first uranium bomb, called “Little Boy” was dropped on Hiroshima. During all three explosions, Alvarez was part of a team of scientists that flew in a specially shielded <mark class="term" data-term="observation" data-term-def="1. The act of noticing something. 2. A record of that which has been noticed." data-term-url="/en/glossary/view/observation/8255">observation</mark> aircraft to observe the explosion and take numerous measurements. As for the consequences of the bomb, Alvarez had an attitude similar to that of many other <mark class="term" data-term="Manhattan Project" data-term-def="A United States project initiated in August 1942 that was responsible for developing atomic technology, and specifically an atomic bomb, during&hellip;" data-term-url="/en/glossary/view/Manhattan+Project/4762">Manhattan Project</mark> contributors. In a letter to his son on the same day as one of the bombings, he wrote:</p><blockquote class="blockquote"> <p>What regrets I have about being a party to killing and maiming thousands of Japanese civilians this morning are tempered with the hope that the terrible weapon we have created may bring the countries of the world together and prevent further wars.</p> <p>- Luis Alvarez in a letter to his son, August 1945 [source: Indiana University, Reactions to Hiroshima]</p> </p></blockquote><p>Essentially, Alvarez was not happy, but he could live with situation knowing that things might have been worse without the bomb. Like all <mark class="term" data-term="Manhattan Project" data-term-def="A United States project initiated in August 1942 that was responsible for developing atomic technology, and specifically an atomic bomb, during&hellip;" data-term-url="/en/glossary/view/Manhattan+Project/4762">Manhattan Project</mark> scientists, near the end of the war, he knew of plans for a US invasion of Japan set for 1946-47 with predictions of massive numbers of deaths that could have dwarfed the Hiroshima and Nagasaki bombings. And so, rather than sink into a state of depression, like many of his colleagues, he put the war behind him and moved onto other areas of physics.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc9621"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">Little Boy and Fat Man were code names for</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-9621-0-option-a" name="quiz-option-9621" type="radio" value="k-electron capture techniques." > <span class="option__label"> <span class="screen-reader-only">a.</span> k-electron capture techniques. </span> </label> <span class="quiz__response" id="response-9621-0"> <strong>Incorrect.</strong> </span> </div> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-9621-1-option-b" name="quiz-option-9621" type="radio" value="atomic bombs." > <span class="option__label"> <span class="screen-reader-only">b.</span> atomic bombs. </span> </label> <span class="quiz__response" id="response-9621-1"> <strong>Correct!</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_3"> <h2>The hydrogen bubble chamber</h2><p>The two atomic bombings of Japan ended the war, and so Alvarez returned to Berkeley, where he was appointed as a full professor in experimental physics. No longer was he applying physics to weapons development, but he was still applying his instrumentation skills. As before the war, Alvarez built new instruments and applied them to <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> aimed at understanding the subatomic world. Since his college graduation in 1932 when only the <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">proton</mark> and <mark class="term" data-term="electron" data-term-def="A subatomic particle with a negative charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 9.11 × 10<sup>-31</sup> kg. Electrons&hellip;" data-term-url="/en/glossary/view/electron/852">electron</mark> had been known, physicists had expanded their knowledge of subatomic <mark class="term" data-term="particle" data-term-def="A tiny piece of matter." data-term-url="/en/glossary/view/particle/8259">particles</mark>. By the early 1950s, that knowledge-base extended to <mark class="term" data-term="neutron" data-term-def="A sub-atomic particle with no charge and a mass of 1.675 × 10<sup>-27</sup> kg. Neutrons are found in the nucleus&hellip;" data-term-url="/en/glossary/view/neutron/1520">neutrons</mark>, positrons, K mesons, and various other “-ons”, but there was still a plethora of particles to be discovered.</p><p>Then, in 1953, Alvarez met a young physicist named Donald Glaser with an invention called a bubble chamber. It used ether, kept at a very cool temperature to remain a <mark class="term" data-term="liquid" data-term-def="The state of matter characterized by its condensed nature and ability to flow. Unlike gases, molecules within a liquid often experience&hellip;" data-term-url="/en/glossary/view/liquid/8727">liquid</mark>, in order to track the pathways of otherwise invisible subatomic <mark class="term" data-term="particle" data-term-def="A tiny piece of matter." data-term-url="/en/glossary/view/particle/8259">particles</mark>. The ether bubble chamber enabled novel particle studies, leading Glaser to win the <mark class="term" data-term="Nobel Prize" data-term-def="Awards made annually, beginning in 1901, from funds originally established by Alfred B. Nobel for outstanding achievement in physics, chemistry, medicine&hellip;" data-term-url="/en/glossary/view/Nobel+Prize/3843">Nobel Prize</mark> in 1960. But long before that happened, Alvarez thought of a way to make the bubble chamber function better, and it was very simple. Instead of ether, he tried using liquid hydrogen, which could be kept at a much lower temperature than ether. </p><p>By 1956, Alvarez had a large hydrogen bubble chamber assembled and the results of the <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> were phenomenal. A whole new collection of subatomic <mark class="term" data-term="particle" data-term-def="A tiny piece of matter." data-term-url="/en/glossary/view/particle/8259">particles</mark> were discovered by Alvarez and others, particles too short-lived to be seen by any other <mark class="term" data-term="method" data-term-def="A procedure or process; a systematic way of performing a task or conducting research." data-term-url="/en/glossary/view/method/8238">method</mark>. In the hydrogen bubble chamber, the particles etched webs of straight and twisting pathways called resonance states, essentially shadows of particles’ movement (Figure 4). This revealed a wealth of fundamental information about the <mark class="term" data-term="atom" data-term-def="The smallest unit of an element that retains the chemical properties of the element. Atoms can exist alone or in&hellip;" data-term-url="/en/glossary/view/atom/1509">atom</mark>, leading Alvarez to receive his own <mark class="term" data-term="Nobel Prize" data-term-def="Awards made annually, beginning in 1901, from funds originally established by Alfred B. Nobel for outstanding achievement in physics, chemistry, medicine&hellip;" data-term-url="/en/glossary/view/Nobel+Prize/3843">Nobel Prize</mark> on December 11, 1968. In his acceptance speech, he made a point of how <mark class="term" data-term="proton" data-term-def="A subatomic (ß link to atom) particle with a positive charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 1.672&hellip;" data-term-url="/en/glossary/view/proton/854">protons</mark> and <mark class="term" data-term="electron" data-term-def="A subatomic particle with a negative charge of 1.60 × 10<sup>-19</sup> coulombs and a mass of 9.11 × 10<sup>-31</sup> kg. Electrons&hellip;" data-term-url="/en/glossary/view/electron/852">electrons</mark> had been the only subatomic particles known during his college years.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_9651.jpg"> <img src="/img/library/modules/mid229/Image/VLObject-9651-160429120431.jpg" alt="Figure 4: Liquid hydrogen bubble chamber photograph of a negatively-charged pi meson interacting with a proton (hydrogen nucleus) to produce a positive K meson and other particles." /> </button> <figcaption> <p><strong>Figure 4</strong>: Liquid hydrogen bubble chamber photograph of a negatively-charged pi meson interacting with a proton (hydrogen nucleus) to produce a positive K meson and other particles.</p> <span class="credit">image ©Department of Energy</span> </figcaption> </figure> </div> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc9626"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">Many new subatomic particles were discovered after Alvarez improved the bubble chamber by using _____.</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-9626-0-option-a" name="quiz-option-9626" type="radio" value="liquid ether" > <span class="option__label"> <span class="screen-reader-only">a.</span> liquid ether </span> </label> <span class="quiz__response" id="response-9626-0"> <strong>Incorrect.</strong> </span> </div> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-9626-1-option-b" name="quiz-option-9626" type="radio" value="liquid hydrogen" > <span class="option__label"> <span class="screen-reader-only">b.</span> liquid hydrogen </span> </label> <span class="quiz__response" id="response-9626-1"> <strong>Correct!</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_4"> <h2>Applying physics to multiple questions of science</h2><p>In 1967, a year before receiving the <mark class="term" data-term="Nobel Prize" data-term-def="Awards made annually, beginning in 1901, from funds originally established by Alfred B. Nobel for outstanding achievement in physics, chemistry, medicine&hellip;" data-term-url="/en/glossary/view/Nobel+Prize/3843">Nobel Prize</mark>, Alvarez came up with a remarkable idea for imaging the inside of Egyptian pyramids. Why not <mark class="term" data-term="X-ray" data-term-def="A form of electromagnetic radiation with higher frequency and energy than any other electromagnetic radiation besides gamma rays. X-rays have various&hellip;" data-term-url="/en/glossary/view/X~ray/7573">X-ray</mark> the structures? he thought. As a child of two generations of physicians, it did make a certain kind of sense, although the sheer size of the pyramids and their thick stone walls meant that literally shooting an X-ray <mark class="term" data-term="beam" data-term-def="A ray or shaft of light from a source." data-term-url="/en/glossary/view/beam/8277">beam</mark> through them would not be practical. But Alvarez was not thinking of X-rays in the literal sense. Instead, thinking back to his first year of graduate school under the mentorship of Arthur Compton, he was cognizant of the fact that cosmic rays were constantly penetrating our planet, along with everything on its <mark class="term" data-term="surface" data-term-def="The outside or external part; the topside face of something." data-term-url="/en/glossary/view/surface/8275">surface</mark>. In other words, the <mark class="term" data-term="radiation" data-term-def="Energy emitted as particles, waves, or rays." data-term-url="/en/glossary/view/radiation/8266">radiation</mark> projector was already in place and turned on. Thus, somebody need only place a cosmic ray detector near an area of a pyramid and the inner contents could then be imaged.</p><p>Alvarez tried the technique at the Pyramid of Chephren, in Giza. While the images revealed no unknown chambers, the technique enabled Alvarez to help archaeologists characterize roughly 20 percent of the pyramid’s <mark class="term" data-term="volume" data-term-def="The amount of space taken up by matter, commonly expressed in cubic centimeters (cm<sup>3</sup>) or milliliters (ml)." data-term-url="/en/glossary/view/volume/8515">volume</mark>. It also served as a prelude for Alvarez to apply <mark class="term" data-term="particle" data-term-def="A tiny piece of matter." data-term-url="/en/glossary/view/particle/8259">particle</mark> physics to another question about the past that was equally as intriguing as ancient Egypt.</p></section> <section id="toc_5"> <h2>What happened to the dinosaurs?</h2><p>By the 1970s, Alvarez’s son, Walter, had also grown up to be a scientist, although instead of physics he studied geology, with a particular interest in paleontology. Today, dinosaurs and <mark class="term" data-term="fossil" data-term-def="The preserved impression or remains of an animal or plant whose living tissue has been replaced by minerals." data-term-url="/en/glossary/view/fossil/8558">fossils</mark> account for a large segment of the toy industry and children’s books, but this was not the case in the 1950s and 60s. In those days, geology hardly ever came up at the dinner table, even in the homes of notable scientists. Being at the forefront of <mark class="term" data-term="particle" data-term-def="A tiny piece of matter." data-term-url="/en/glossary/view/particle/8259">particle</mark> physics, Alvarez thought that geology was boring. He could not fathom why his son would be interested in digging up rocks and cutting into them. But the boy grew up and made a career of it.</p><p>In 1977, he mentioned to his father a problem in the rock layers known as the K/T <mark class="term" data-term="boundary" data-term-def="A line or limit that divides one area from another." data-term-url="/en/glossary/view/boundary/8272">boundary</mark>. The K/T boundary is a layer of clay, a visible line within the rock layers, that exists all over the planet at a depth corresponding to the end of the Mesozoic Era, 65 million years ago. It is also a boundary in time, marking the time span between the Cretaceous period (the "K") and the Tertiary period (the "T"). The K/T boundary had been discovered early in the 19th century and by Alvarez’s time geologists knew that it corresponded to the demise of the dinosaurs, and for a very simple reason. Below the boundary, there are dinosaur <mark class="term" data-term="fossil" data-term-def="The preserved impression or remains of an animal or plant whose living tissue has been replaced by minerals." data-term-url="/en/glossary/view/fossil/8558">fossils</mark>, while none exist above it. In other words, the dinosaurs went <mark class="term" data-term="extinction" data-term-url="/en/glossary/view/extinction" data-term-def="The complete and permanent loss of all individuals of a species of organism.">extinct</mark> rather abruptly, but nobody knew why.</p></section> <section id="toc2_2"><h3>Iridium and the K/T boundary</h3><p>Even though Alvarez lacked an interest in geology, he loved the idea of applying physics to help his son solve the mystery (Figure 5). It was not a simple matter. It required knowledge not just of <mark class="term" data-term="particle" data-term-def="A tiny piece of matter." data-term-url="/en/glossary/view/particle/8259">particle</mark> physics, but astrophysics too, because Alvarez had a strong suspicion that the answer must involve outer space. Thus, as with the pyramids, Alvarez tapped into his background from graduate school <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark> on cosmic rays. He decided that the answer might have to do with the <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">element</mark> iridium. Iridium is a very rare element in the Earth’s <mark class="term" data-term="crust" data-term-def="The uppermost 5-70 km of the Earth. There are two types of crust: continental and oceanic. Continental crust ranges from 10-70&hellip;" data-term-url="/en/glossary/view/crust/880">crust</mark>, but it is more common in certain celestial objects, especially comets, asteroids, and meteorites. After making several calculations regarding the expected iridium <mark class="term" data-term="concentration" data-term-def="The amount of one substance in relation to other components within a given area." data-term-url="/en/glossary/view/concentration/8733">concentrations</mark> in and around the clay layer, Alvarez turned to his colleagues Frank Asaro and Helen Vaughn Michel of the <mark class="term" data-term="radiation" data-term-def="Energy emitted as particles, waves, or rays." data-term-url="/en/glossary/view/radiation/8266">radiation</mark> lab at Berkeley (by this time called Lawrence Berkeley National Laboratory or “LBL”) to make precise measurements of the iridium level in the K/T <mark class="term" data-term="boundary" data-term-def="A line or limit that divides one area from another." data-term-url="/en/glossary/view/boundary/8272">boundary</mark> clay.</p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_9652.jpg"> <img src="/img/library/modules/mid229/Image/VLObject-9652-160429030418.jpg" alt="Figure 5: Luis with his son Walter, a geologist, examining rock outcroppings." /> </button> <figcaption> <p><strong>Figure 5</strong>: Luis with his son Walter, a geologist, examining rock outcroppings.</p> <span class="credit">image ©2010 The Regents of the University of California, Lawrence Berkeley National Laboratory</span> </figcaption> </figure> </div> <p>Seeing their mentor with rock samples in the lab, graduate students and postdoctoral fellows would often ask Alvarez what he was doing, since it didn’t seem to correspond with the usual physics <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark>. Occasionally, he asked if they’d like to get involved and usually they politely declined. One Alvarez protégé, Richard Muller, now a senior scientist at the Lawrence Berkeley Lab, recalls declining the offer with a sigh, thinking the K/T project had little potential; the respected scientist simply wanted to work with his son. Regarding Alvarez’s motivations, Muller was 100 percent correct. He really was doing it just to work with his son. Indeed, Alvarez himself didn’t expect the project would go anywhere scientifically. But when the team members looked at the results, they were startled.</p><p>The iridium <mark class="term" data-term="concentration" data-term-def="The amount of one substance in relation to other components within a given area." data-term-url="/en/glossary/view/concentration/8733">concentration</mark> at the precise level of the dinosaurs’ <mark class="term" data-term="extinction" data-term-def="The complete and permanent loss of all individuals of a species of organism." data-term-url="/en/glossary/view/extinction/5615">extinction</mark> was higher than anyone would have believed. In K/T samples taken from different sites on the planet, the iridium concentration was found to be at least 20 times as high as before and after the K/T extinction event, and in some parts of Earth, the K/T iridium level was found to be as high as 160 times the normal level.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form class="" name="cc9637"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">The element iridium is very rare in ______.</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-9637-0-option-a" name="quiz-option-9637" type="radio" value="Earth's crust" > <span class="option__label"> <span class="screen-reader-only">a.</span> Earth's crust </span> </label> <span class="quiz__response" id="response-9637-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-9637-1-option-b" name="quiz-option-9637" type="radio" value="comets and asteroids" > <span class="option__label"> <span class="screen-reader-only">b.</span> comets and asteroids </span> </label> <span class="quiz__response" id="response-9637-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc2_3"><h3>Astrophysics and the demise of the dinosaurs</h3><p>Based on these results, in 1980 Luis and Walter together with colleagues Frank Asaro and Helen Michel published a paper in the journal <em>Science</em>, hypothesizing that the K/T <mark class="term" data-term="extinction" data-term-def="The complete and permanent loss of all individuals of a species of organism." data-term-url="/en/glossary/view/extinction/5615">extinction</mark>, which involved numerous life forms including the dinosaurs, had an extraterrestrial cause. Based on Alvarez’s calculations, the team proposed that a comet or asteroid 10-kilometers wide had stricken the world of the dinosaurs at 25 kilometers per second, leaving a layer of iridium and ejecting dust in the <mark class="term" data-term="atmosphere" data-term-def="The collective mass of gases that surrounds the Earth or another planet." data-term-url="/en/glossary/view/atmosphere/8529">atmosphere</mark>, blocking <mark class="term" data-term="light" data-term-def="A form of electromagnetic radiation. Visible light is that associated with stimulating the organs of sight, which for normal human&hellip;" data-term-url="/en/glossary/view/light/1498">light</mark> from the sun (Figure 6). This, in turn, had interfered with <mark class="term" data-term="photosynthesis" data-term-def="Formation of carbohydrates from carbon dioxide and a source of hydrogen (as water) in the chlorophyll-containing tissues of plants exposed to light." data-term-url="/en/glossary/view/photosynthesis/2194">photosynthesis</mark> and triggered a <mark class="term" data-term="climate" data-term-def="Climate describes the average and patterns of a particular area’s weather over time. Climate includes such elements as temperature, precipitation, humidity,&hellip;" data-term-url="/en/glossary/view/climate/9334">climate</mark> change, causing disruption of the web of life. </p> <div class="figure"> <figure> <button class="lightbox-button lightbox-button--icon" data-lightbox="" data-lightbox-src="/img/library/large_images/image_9033.jpg"> <img src="/img/library/modules/mid229/Image/VLObject-9033-151017031058.jpg" alt="Figure 6: An artist's rendering of an asteroid impacting the Yucatán peninsula, an area now near the Mexican town of Chicxulub, at the end of the Cretaceous ^~period." /> </button> <figcaption> <p><strong>Figure 6</strong>: An artist's rendering of an asteroid impacting the Yucatán peninsula, an area now near the Mexican town of Chicxulub, at the end of the Cretaceous ^~period.</p> <span class="credit">image ©Don Davis, NASA</span> </figcaption> </figure> </div> <p>Given the apparent arrival of a large amount of iridium at the time of <mark class="term" data-term="extinction" data-term-def="The complete and permanent loss of all individuals of a species of organism." data-term-url="/en/glossary/view/extinction/5615">extinction</mark>, the <mark class="term" data-term="hypothesis" data-term-def="From the Greek word <em>hypothesis</em> meaning assumption or the basis of an argument, a hypothesis is a proposal intended to explain&hellip;" data-term-url="/en/glossary/view/hypothesis/3727">hypothesis</mark> was very strong. Nevertheless, scientists were not all convinced, and paleontologists in particular were divided. Some found the hypothesis intriguing, but others dismissed it on the grounds that the mere presence of iridium did not prove that an object large enough to cause such widespread extinction had struck the Earth at the end of the Mesozoic era. At the time, there was an emerging <mark class="term" data-term="theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;" data-term-url="/en/glossary/view/theory/4854">theory</mark>, based on limited <mark class="term" data-term="evidence" data-term-def="Support for an idea, opinion, or hypothesis." data-term-url="/en/glossary/view/evidence/8243">evidence</mark> but a strong rationale, that the K/T extinction period corresponded to an age of massive volcanic events.</p><p>To sway the paleontology community away from the volcanic explanation and to accept their idea, the Alvarez team needed an additional piece of <mark class="term" data-term="evidence" data-term-def="Support for an idea, opinion, or hypothesis." data-term-url="/en/glossary/view/evidence/8243">evidence</mark>, namely a crater left over from the impacting asteroid or comet. People looked around for such an impact crater and ultimately named a few candidates, one in particular in the Arizona desert, but it was far too small. An impact consistent with Alvarez’s calculations, made by an object 10 kilometers wide striking the ground at 25 kilometers per second, would have released <mark class="term" data-term="energy" data-term-def="An abstract property defined as the capacity to do work. The basic forms of energy include chemical, electrical, mechanical, nuclear, and&hellip;" data-term-url="/en/glossary/view/energy/1497">energy</mark> on an enormous scale. To get an idea of how enormous, one must consider that the nuclear arms race that began when Alvarez worked on the first bombs in the 1940s reached a peak in the 1980s when the combined arsenal of the United States and USSR numbered more than 70,000 nuclear bombs. Were all those bombs detonated together over a single spot, the explosion would release only a fraction of the energy of the impact that Alvarez calculated as the cause of the demise of the dinosaurs. That kind of impact would leave a crater more than 100 km wide and several km deep, and no craters that anyone could find by the mid 1980s were anywhere near that big.</p><p>Alvarez died in 1988, just two years before a discovery that would change the tide regarding his <mark class="term" data-term="hypothesis" data-term-def="From the Greek word <em>hypothesis</em> meaning assumption or the basis of an argument, a hypothesis is a proposal intended to explain&hellip;" data-term-url="/en/glossary/view/hypothesis/3727">hypothesis</mark>. In the 1990s, using satellite imaging over the Gulf of Mexico, a team of scientists that included Adriana Ocampo took notice of the Chicxulub crater, on the <mark class="term" data-term="seafloor" data-term-def="The bottom surface of the ocean." data-term-url="/en/glossary/view/seafloor/8280">seafloor</mark> off the coast of the Yucatan Peninsula in Mexico. For years, there had been hints of the crater, but new advances in spacecraft imaging now allowed for an accurate assessment of the crater’s size. It was found to be huge, 180 km in diameter and 20 km deep. Examination of the details showed it to be precisely the kind of crater that would be formed from an impact of Alvarez’s calculations.</p><p>Science is full of surprises, not just involving discoveries about nature, but also connected with how society remembers the discoverers. The story of Luis Walter Alvarez is such a case. His work has touched so many areas of science, not all of which are even mentioned here, yet uncovering the demise of the dinosaurs may end up as his greatest legacy. This may seem odd, since he won the <mark class="term" data-term="Nobel Prize" data-term-def="Awards made annually, beginning in 1901, from funds originally established by Alfred B. Nobel for outstanding achievement in physics, chemistry, medicine&hellip;" data-term-url="/en/glossary/view/Nobel+Prize/3843">Nobel Prize</mark> for something completely different, but such unpredictable <mark class="term" data-term="outcome" data-term-def="Result." data-term-url="/en/glossary/view/outcome/8247">outcomes</mark> make the history of science all the more interesting. </p> </div> </section> <hr class="border-color-dark" /> <footer class="module__footer"> <p class="citation"> <em> David Warmflash, MD “Luis Walter Alvarez” Visionlearning Vol. SCIRE-2 (5), 2016. </em> </p>  <div class="title-list" id="refs" name="refs"> <p class="h6 title-list__title"> References </p> <ul class="title-list__list"> <li><p>Alvarez, L.W., Alvarez, W., Asaro, F., Michel, H.V. 1980. Extraterrestrial cause for the Cretaceous-Tertiary extinction. <em>Science 208</em>(4448):1095-1108.</li> <li>Luis Alvarez. <em>Famous Scientists</em>. Retrieved August 28, 2015</li> <li>http://www.famousscientists.org/luis-alvarez/</li> <li>Muller, R. 2008. The death of the dinosaurs: 27 years later. Lawrence Berkeley National Laboratory lecture. Retrieved September 19, 2015</li> <li>https://www.youtube.com/watch?v=8WzgUZbhrLc</li> <li>Nobel Foundation. 1968. Luis Alvarez – Biographical. <em>Nobelprize.org</em>. Retrieved September 19, 2015</li> <li>http://www.nobelprize.org/nobel_prizes/physics/laureates/1968/alvarez-bio.html</li> <li>Pace, D., and Wittman, L. 2004, Fall. Reactions to Hiroshima. <em>W100: Images of the Future - A History</em>. Bloomington, IN: Indiana University.</li> <li>Retrieved September 29, 2015</li> <li>http://www.indiana.edu/~futhist2/Part4/Wk12/reactions.htm</li> <li>Sullivan, W. 1988, September 2. Luis W. Alvarez, Nobel physicist who explored atom, dies at 77. <em>New York Times</em>. Retrieved August 28, 2015</li> <li>http://www.nytimes.com/1988/09/02/obituaries/luis-w-alvarez-nobel-physicist-who-explored-atom-dies-at-77.html</li> <li>WGBH. 1998. Luis Alvarez 1911 - 1988. <em>A science discovery: people and discoveries</em>. PBS. Retrieved August 28, 2015</li> <li>http://www.pbs.org/wgbh/aso/databank/entries/boalva.html</li> </ul> </div>  <div class="title-list" name="further"> <p class="h6 title-list__title"> Further Reading </p> <ul class="grid grid--column-2--md grid--column-3--md gap-1"> </ul> </div> </footer> </div>   </div>  <div class="order-1 order-2--lg module__tools"> <div class="narrow margin-x-auto position-sticky-top font-size-md"> <div class="padding-2 border-radius box-shadow-1--lg"> <div class="tabs" role="tablist"> <nav> <button class="button button--icon-label" id="tab-button-in-this-module" aria-label="Table of Contents" aria-controls="tab-panel-module__tools" aria-selected="true" role="tab"> <span class="icon icon-list" aria-hidden="true"></span> <span class="button__text">Contents</span> </button> <button class="button button--icon-label" id="tab-button-toggle-terms" aria-controls="tab-panel-toggle-terms" aria-selected="false" role="tab"> <span class="icon icon-glossary-highlight"></span> <span class="button__text">Glossary Terms</span> </button> </nav> <hr class="divider" /> <div class="tabs__panel shown" id="tab-panel-module__tools" aria-labelledby="tab-button-module__tools" role="tabpanel"> <p class="font-weight-bold margin-bottom-1"> Table of Contents </p> <div class="table-of-contents" id="module-toc"> <ul> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229#toc_1">Born into a family of medicine</a> </li> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229#toc_2">Back to the Bay Area to start his career</a> </li> <li> <ul> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229#toc2_1">Top-secret nuclear science</a> </li> </ul> </li> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229#toc_3">The hydrogen bubble chamber</a> </li> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229#toc_4">Applying physics to multiple questions of science</a> </li> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229#toc_5">What happened to the dinosaurs?</a> </li> <li> <ul> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229#toc2_2">Iridium and the K/T boundary</a> </li> </ul> </li> <li> <ul> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229#toc2_3">Astrophysics and the demise of the dinosaurs</a> </li> </ul> </li> </ul> </div> </div>   <div class="tabs__panel" id="tab-panel-toggle-terms" aria-labelledby="tab-button-toggle-terms" role="tabpanel"> <div class="reading-toggle"> <div class="reading-toggle__switch"> <div class="form-entry__option__switch"> <label> <input type="checkbox" name="termsToggleSwitch" id="terms-toggle-switch" /> <span class="switch__slider"></span> <span class="option__label text-decoration-none font-size-md"> Highlight Glossary Terms </span> </label> </div> </div> <div class="reading-toggle__help"> <p> <em> Activate glossary term highlighting to easily identify key terms within the module. 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Luis Walter Alvarez | Scientists and Research | Visionlearning