The greatest mathematician that never lived - Pratik Aghor

2,665,947 views ・ 2020-07-06

TED-Ed


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

00:06
When Nicolas Bourbaki applied to the American Mathematical Society
0
6930
4606
00:11
in the 1950s,
1
11536
1390
00:12
he was already one of the most influential mathematicians of his time.
2
12926
4160
00:17
He’d published articles in international journals
3
17086
2680
00:19
and his textbooks were required reading.
4
19766
2680
00:22
Yet his application was firmly rejected for one simple reason—
5
22446
4961
00:27
Nicolas Bourbaki did not exist.
6
27407
3580
00:30
Two decades earlier, mathematics was in disarray.
7
30987
3610
00:34
Many established mathematicians had lost their lives in the first World War,
8
34597
4648
00:39
and the field had become fragmented.
9
39245
2240
00:41
Different branches used disparate methodology to pursue their own goals.
10
41485
4455
00:45
And the lack of a shared mathematical language
11
45940
2690
00:48
made it difficult to share or expand their work.
12
48630
3490
00:52
In 1934, a group of French mathematicians were particularly fed up.
13
52120
5336
00:57
While studying at the prestigious École normale supérieure,
14
57456
3420
01:00
they found the textbook for their calculus class so disjointed
15
60876
4133
01:05
that they decided to write a better one.
16
65009
2930
01:07
The small group quickly took on new members,
17
67939
2530
01:10
and as the project grew, so did their ambition.
18
70469
3320
01:13
The result was the "Éléments de mathématique,"
19
73789
2710
01:16
a treatise that sought to create a consistent logical framework
20
76499
3810
01:20
unifying every branch of mathematics.
21
80309
2540
01:22
The text began with a set of simple axioms—
22
82849
3198
01:26
laws and assumptions it would use to build its argument.
23
86047
3740
01:29
From there, its authors derived more and more complex theorems
24
89787
3820
01:33
that corresponded with work being done across the field.
25
93607
3800
01:37
But to truly reveal common ground,
26
97407
2220
01:39
the group needed to identify consistent rules
27
99627
3160
01:42
that applied to a wide range of problems.
28
102787
3170
01:45
To accomplish this, they gave new, clear definitions
29
105957
3430
01:49
to some of the most important mathematical objects,
30
109387
3092
01:52
including the function.
31
112479
2220
01:54
It’s reasonable to think of functions as machines
32
114699
3030
01:57
that accept inputs and produce an output.
33
117729
3260
02:00
But if we think of functions as bridges between two groups,
34
120989
3900
02:04
we can start to make claims about the logical relationships between them.
35
124889
4116
02:09
For example, consider a group of numbers and a group of letters.
36
129005
4119
02:13
We could define a function where every numerical input corresponds
37
133124
4000
02:17
to the same alphabetical output,
38
137124
2440
02:19
but this doesn’t establish a particularly interesting relationship.
39
139564
4000
02:23
Alternatively, we could define a function where every numerical input
40
143564
4261
02:27
corresponds to a different alphabetical output.
41
147825
3440
02:31
This second function sets up a logical relationship
42
151265
3440
02:34
where performing a process on the input has corresponding effects
43
154705
4102
02:38
on its mapped output.
44
158807
2050
02:40
The group began to define functions by how they mapped elements across domains.
45
160857
5453
02:46
If a function’s output came from a unique input,
46
166310
3395
02:49
they defined it as injective.
47
169705
2720
02:52
If every output can be mapped onto at least one input,
48
172425
4000
02:56
the function was surjective.
49
176425
1850
02:58
And in bijective functions, each element had perfect one to one correspondence.
50
178275
5750
03:04
This allowed mathematicians to establish logic that could be translated
51
184025
4502
03:08
across the function’s domains in both directions.
52
188527
4320
03:12
Their systematic approach to abstract principles
53
192847
3070
03:15
was in stark contrast to the popular belief that math was an intuitive science,
54
195917
5177
03:21
and an over-dependence on logic constrained creativity.
55
201094
4198
03:25
But this rebellious band of scholars gleefully ignored conventional wisdom.
56
205292
4626
03:29
They were revolutionizing the field, and they wanted to mark the occasion
57
209918
4171
03:34
with their biggest stunt yet.
58
214089
2360
03:36
They decided to publish "Éléments de mathématique"
59
216449
2650
03:39
and all their subsequent work under a collective pseudonym:
60
219099
4164
03:43
Nicolas Bourbaki.
61
223263
2292
03:45
Over the next two decades, Bourbaki’s publications became standard references.
62
225555
5405
03:50
And the group’s members took their prank as seriously as their work.
63
230960
5097
03:56
Their invented mathematician claimed to be a reclusive Russian genius
64
236057
4737
04:00
who would only meet with his selected collaborators.
65
240794
3300
04:04
They sent telegrams in Bourbaki’s name, announced his daughter’s wedding,
66
244094
4304
04:08
and publicly insulted anyone who doubted his existence.
67
248398
4219
04:12
In 1968, when they could no longer maintain the ruse,
68
252617
4000
04:16
the group ended their joke the only way they could.
69
256617
3430
04:20
They printed Bourbaki’s obituary, complete with mathematical puns.
70
260047
5606
04:25
Despite his apparent death, the group bearing Bourbaki’s name lives on today.
71
265653
5084
04:30
Though he’s not associated with any single major discovery,
72
270737
3570
04:34
Bourbaki’s influence informs much current research.
73
274307
3330
04:37
And the modern emphasis on formal proofs owes a great deal to his rigorous methods.
74
277637
5771
04:43
Nicolas Bourbaki may have been imaginary— but his legacy is very real.
75
283408
5830
About this website

This site will introduce you to YouTube videos that are useful for learning English. You will see English lessons taught by top-notch teachers from around the world. Double-click on the English subtitles displayed on each video page to play the video from there. The subtitles scroll in sync with the video playback. If you have any comments or requests, please contact us using this contact form.

https://forms.gle/WvT1wiN1qDtmnspy7