The greatest mathematician that never lived - Pratik Aghor

2,628,586 views ・ 2020-07-06

TED-Ed


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When Nicolas Bourbaki applied to the American Mathematical Society
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in the 1950s,
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he was already one of the most influential mathematicians of his time.
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He’d published articles in international journals
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and his textbooks were required reading.
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Yet his application was firmly rejected for one simple reason—
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Nicolas Bourbaki did not exist.
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Two decades earlier, mathematics was in disarray.
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Many established mathematicians had lost their lives in the first World War,
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and the field had become fragmented.
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Different branches used disparate methodology to pursue their own goals.
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And the lack of a shared mathematical language
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made it difficult to share or expand their work.
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In 1934, a group of French mathematicians were particularly fed up.
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While studying at the prestigious École normale supérieure,
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they found the textbook for their calculus class so disjointed
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that they decided to write a better one.
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The small group quickly took on new members,
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and as the project grew, so did their ambition.
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The result was the "Éléments de mathématique,"
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a treatise that sought to create a consistent logical framework
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unifying every branch of mathematics.
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The text began with a set of simple axioms—
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laws and assumptions it would use to build its argument.
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From there, its authors derived more and more complex theorems
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that corresponded with work being done across the field.
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But to truly reveal common ground,
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the group needed to identify consistent rules
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that applied to a wide range of problems.
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To accomplish this, they gave new, clear definitions
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to some of the most important mathematical objects,
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including the function.
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It’s reasonable to think of functions as machines
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that accept inputs and produce an output.
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But if we think of functions as bridges between two groups,
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we can start to make claims about the logical relationships between them.
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For example, consider a group of numbers and a group of letters.
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We could define a function where every numerical input corresponds
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to the same alphabetical output,
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but this doesn’t establish a particularly interesting relationship.
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Alternatively, we could define a function where every numerical input
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corresponds to a different alphabetical output.
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This second function sets up a logical relationship
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where performing a process on the input has corresponding effects
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on its mapped output.
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The group began to define functions by how they mapped elements across domains.
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If a function’s output came from a unique input,
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they defined it as injective.
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If every output can be mapped onto at least one input,
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the function was surjective.
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And in bijective functions, each element had perfect one to one correspondence.
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This allowed mathematicians to establish logic that could be translated
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across the function’s domains in both directions.
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Their systematic approach to abstract principles
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was in stark contrast to the popular belief that math was an intuitive science,
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and an over-dependence on logic constrained creativity.
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But this rebellious band of scholars gleefully ignored conventional wisdom.
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They were revolutionizing the field, and they wanted to mark the occasion
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with their biggest stunt yet.
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They decided to publish "Éléments de mathématique"
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and all their subsequent work under a collective pseudonym:
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Nicolas Bourbaki.
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Over the next two decades, Bourbaki’s publications became standard references.
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And the group’s members took their prank as seriously as their work.
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Their invented mathematician claimed to be a reclusive Russian genius
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who would only meet with his selected collaborators.
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They sent telegrams in Bourbaki’s name, announced his daughter’s wedding,
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and publicly insulted anyone who doubted his existence.
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In 1968, when they could no longer maintain the ruse,
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the group ended their joke the only way they could.
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They printed Bourbaki’s obituary, complete with mathematical puns.
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Despite his apparent death, the group bearing Bourbaki’s name lives on today.
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Though he’s not associated with any single major discovery,
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Bourbaki’s influence informs much current research.
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And the modern emphasis on formal proofs owes a great deal to his rigorous methods.
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Nicolas Bourbaki may have been imaginary— but his legacy is very real.
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