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Plato, Applied Math, and You

Posted by Josh Rothman  June 29, 2011 02:15 PM

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The modern world, from its microchips to its architecture, is built upon the foundations of mathematics. It's easy to take that fact for granted, just as it's easy to take in stride the fact that, in today's universities, "applied math" majors are on the lookout for more ways to connect the mathematical with the practical. And yet the connection between math and reality, is, when you think about, actually quite strange. Writing in the math magazine Plus, mathematician Phil Wilson explores the implications of the "stunning fact" that "the world can be understood mathematically": "Why," he asks, "is applied maths even possible?"

No one's mystified by the way that language describes the world, albeit imperfectly: it's a human invention that's evolved, over time, to be fairly accurate and illuminating. Mathematics, though, seems like something else altogether, because of two apparently contradictory facts. First, there's the fact that math describes the world with breathtaking exactness, to the degree that we say that reality is "governed" by mathematical laws. And second, there's the fact that math also seems like its own autonomous world, full of intricate patterns and relationships that don't (yet) have any real-world analogues. How can math be simultaneously perfectly realistic and totally bizarre?

Wilson explains the different ways that philosophers of math, or "metamathematicians," have thought about these problems through the ages. Today, he argues, most mathematicians have settled on a form of Platonism. They understand themselves as exploring  "what feels like a platonic realm -- they don't invent their mathematics, they discover it." Many believe that the physical world "emerges," somehow, out of a mathematical one, and that both worlds are, in a sense, real. Mathematicians keep their platonism under wraps, however, because it feels mystical and weird: "It is not natural," Wilson explains, "for a philosopher or scientist to wholeheartedly embrace such a view (even if they may wish to) since it tends to encourage the preservation of mystery rather than the drawing back of the obscuring veil." And yet there the mystery is, plain as day to anyone who thinks about it, and suggestive of all sorts of metaphysical and theological questions.

Wilson offers, unsurprisingly, no solution to to the mystery -- but he does point to ways to think about it more clearly. One way is illustrated proposed by the metamathematician Roger Penrose in his "three world diagram":

The diagram, Wilson writes, shows how at least some of the platonic, mathematical world is embedded or expressed in the physical world; how at least some of that physical world is embedded or expressed in our mental world; and how at least part of that mental world is embedded or expressed in the platonic world. It seems as though there are three worlds, or three levels of reality; "each world," Wilson concludes, "remains a mystery," especially when it comes to its relation to the others. A fascinating discussion: read the whole thing here.

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About brainiac Brainiac is the daily blog of the Globe's Sunday Ideas section, covering news and delights from the worlds of art, science, literature, history, design, and more. You can follow us on Twitter @GlobeIdeas.
Brainiac blogger Kevin Hartnett is a writer in Columbia, South Carolina. He can be reached here.

Leon Neyfakh is the staff writer for Ideas. Amanda Katz is the deputy Ideas editor. Stephen Heuser is the Ideas editor.

Guest blogger Simon Waxman is Managing Editor of Boston Review and has written for WBUR, Alternet, McSweeney's, Jacobin, and others.

Guest blogger Elizabeth Manus is a writer living in New York City. She has been a book review editor at the Boston Phoenix, and a columnist for The New York Observer and Metro.

Guest blogger Sarah Laskow is a freelance writer and editor in New York City. She edits Smithsonian's SmartNews blog and has contributed to Salon, Good, The American Prospect, Bloomberg News, and other publications.

Guest blogger Joshua Glenn is a Boston-based writer, publisher, and freelance semiotician. He was the original Brainiac blogger, and is currently editor of the blog HiLobrow, publisher of a series of Radium Age science fiction novels, and co-author/co-editor of several books, including the story collection "Significant Objects" and the kids' field guide to life "Unbored."

Guest blogger Ruth Graham is a freelance journalist in New Hampshire, and a frequent Ideas contributor. She is a former features editor for the New York Sun, and has written for publications including Slate and the Wall Street Journal.

Joshua Rothman is a graduate student and Teaching Fellow in the Harvard English department, and an Instructor in Public Policy at the Harvard Kennedy School of Government. He teaches novels and political writing.


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