Is math discovered or invented? - Jeff Dekofsky

3,166,355 views ・ 2014-10-27

TED-Ed


Please double-click on the English subtitles below to play the video.

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Would mathematics exist if people didn't?
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Since ancient times, mankind has hotly debated
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whether mathematics was discovered or invented.
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Did we create mathematical concepts to help us understand the universe around us,
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or is math the native language of the universe itself,
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existing whether we find its truths or not?
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Are numbers, polygons and equations truly real,
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or merely ethereal representations of some theoretical ideal?
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The independent reality of math has some ancient advocates.
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The Pythagoreans of 5th Century Greece believed numbers were both
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living entities and universal principles.
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They called the number one, "the monad," the generator of all other numbers
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and source of all creation.
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Numbers were active agents in nature.
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Plato argued mathematical concepts were concrete
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and as real as the universe itself, regardless of our knowledge of them.
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Euclid, the father of geometry, believed nature itself
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was the physical manifestation of mathematical laws.
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Others argue that while numbers may or may not exist physically,
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mathematical statements definitely don't.
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Their truth values are based on rules that humans created.
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Mathematics is thus an invented logic exercise,
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with no existence outside mankind's conscious thought,
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a language of abstract relationships based on patterns discerned by brains,
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built to use those patterns to invent useful but artificial order from chaos.
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One proponent of this sort of idea was Leopold Kronecker,
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a professor of mathematics in 19th century Germany.
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His belief is summed up in his famous statement:
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"God created the natural numbers, all else is the work of man."
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During mathematician David Hilbert's lifetime,
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there was a push to establish mathematics as a logical construct.
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Hilbert attempted to axiomatize all of mathematics,
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as Euclid had done with geometry.
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He and others who attempted this saw mathematics as a deeply philosophical game
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but a game nonetheless.
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Henri Poincaré, one of the father's of non-Euclidean geometry,
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believed that the existence of non-Euclidean geometry,
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dealing with the non-flat surfaces of hyperbolic and elliptical curvatures,
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proved that Euclidean geometry, the long standing geometry of flat surfaces,
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was not a universal truth,
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but rather one outcome of using one particular set of game rules.
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But in 1960, Nobel Physics laureate Eugene Wigner
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coined the phrase, "the unreasonable effectiveness of mathematics,"
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pushing strongly for the idea that mathematics is real
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and discovered by people.
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Wigner pointed out that many purely mathematical theories
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developed in a vacuum, often with no view towards describing any physical phenomena,
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have proven decades or even centuries later,
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to be the framework necessary to explain
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how the universe has been working all along.
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For instance, the number theory of British mathematician Gottfried Hardy,
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who had boasted that none of his work would ever be found useful
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in describing any phenomena in the real world,
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helped establish cryptography.
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Another piece of his purely theoretical work
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became known as the Hardy-Weinberg law in genetics,
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and won a Nobel prize.
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And Fibonacci stumbled upon his famous sequence
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while looking at the growth of an idealized rabbit population.
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Mankind later found the sequence everywhere in nature,
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from sunflower seeds and flower petal arrangements,
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to the structure of a pineapple,
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even the branching of bronchi in the lungs.
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Or there's the non-Euclidean work of Bernhard Riemann in the 1850s,
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which Einstein used in the model for general relativity a century later.
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Here's an even bigger jump:
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mathematical knot theory, first developed around 1771
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to describe the geometry of position,
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was used in the late 20th century to explain how DNA unravels itself
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during the replication process.
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It may even provide key explanations for string theory.
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Some of the most influential mathematicians and scientists
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of all of human history have chimed in on the issue as well,
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often in surprising ways.
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So, is mathematics an invention or a discovery?
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Artificial construct or universal truth?
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Human product or natural, possibly divine, creation?
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These questions are so deep the debate often becomes spiritual in nature.
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The answer might depend on the specific concept being looked at,
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but it can all feel like a distorted zen koan.
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If there's a number of trees in a forest, but no one's there to count them,
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does that number exist?
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