1
00:00:00,588 --> 00:00:04,720
If you look deep into the night sky,

2
00:00:04,720 --> 00:00:06,386
you see stars,

3
00:00:06,386 --> 00:00:08,698
and if you look further, you see more stars,

4
00:00:08,698 --> 00:00:10,827
and further, galaxies, and further, more galaxies.

5
00:00:10,827 --> 00:00:14,750
But if you keep looking further and further,

6
00:00:14,750 --> 00:00:17,906
eventually you see nothing for a long while,

7
00:00:17,906 --> 00:00:22,308
and then finally you see a faint, fading afterglow,

8
00:00:22,308 --> 00:00:25,452
and it's the afterglow of the Big Bang.

9
00:00:25,452 --> 00:00:28,239
Now, the Big Bang was an era in the early universe

10
00:00:28,239 --> 00:00:30,320
when everything we see in the night sky

11
00:00:30,320 --> 00:00:32,770
was condensed into an incredibly small,

12
00:00:32,770 --> 00:00:37,236
incredibly hot, incredibly roiling mass,

13
00:00:37,236 --> 00:00:39,868
and from it sprung everything we see.

14
00:00:39,868 --> 00:00:42,667
Now, we've mapped that afterglow

15
00:00:42,667 --> 00:00:44,276
with great precision,

16
00:00:44,276 --> 00:00:46,420
and when I say me, I mean people who aren't me.

17
00:00:46,420 --> 00:00:48,356
We've mapped the afterglow

18
00:00:48,356 --> 00:00:49,948
with spectacular precision,

19
00:00:49,948 --> 00:00:51,276
and one of the shocks about it

20
00:00:51,276 --> 00:00:53,972
is that it's almost completely uniform.

21
00:00:53,972 --> 00:00:56,028
Fourteen billion light years that way

22
00:00:56,028 --> 00:00:57,900
and 14 billion light years that way,

23
00:00:57,900 --> 00:00:59,408
it's the same temperature.

24
00:00:59,408 --> 00:01:02,532
Now it's been 13 billion years

25
00:01:02,532 --> 00:01:04,420
since that Big Bang,

26
00:01:04,420 --> 00:01:06,972
and so it's got faint and cold.

27
00:01:06,972 --> 00:01:09,270
It's now 2.7 degrees.

28
00:01:09,270 --> 00:01:11,420
But it's not exactly 2.7 degrees.

29
00:01:11,420 --> 00:01:13,444
It's only 2.7 degrees to about

30
00:01:13,444 --> 00:01:15,596
10 parts in a million.

31
00:01:15,596 --> 00:01:16,700
Over here, it's a little hotter,

32
00:01:16,700 --> 00:01:18,468
and over there, it's a little cooler,

33
00:01:18,468 --> 00:01:21,596
and that's incredibly important
to everyone in this room,

34
00:01:21,596 --> 00:01:23,380
because where it was a little hotter,

35
00:01:23,380 --> 00:01:25,156
there was a little more stuff,

36
00:01:25,156 --> 00:01:26,733
and where there was a little more stuff,

37
00:01:26,733 --> 00:01:28,532
we have galaxies and clusters of galaxies

38
00:01:28,532 --> 00:01:29,824
and superclusters

39
00:01:29,824 --> 00:01:32,372
and all the structure you see in the cosmos.

40
00:01:32,372 --> 00:01:35,684
And those small, little, inhomogeneities,

41
00:01:35,684 --> 00:01:37,916
20 parts in a million,

42
00:01:37,916 --> 00:01:40,500
those were formed by quantum mechanical wiggles

43
00:01:40,500 --> 00:01:42,308
in that early universe that were stretched

44
00:01:42,308 --> 00:01:44,837
across the size of the entire cosmos.

45
00:01:44,837 --> 00:01:46,501
That is spectacular,

46
00:01:46,501 --> 00:01:48,306
And that's not what they found on Monday.

47
00:01:48,306 --> 00:01:50,332
What they found on Monday is cooler.

48
00:01:50,332 --> 00:01:52,638
So here's what they found on Monday.

49
00:01:52,638 --> 00:01:55,901
Imagine you take some hot, you take a bell,

50
00:01:55,901 --> 00:01:57,612
and you whack the bell with a hammer.

51
00:01:57,612 --> 00:01:59,348
What happens? It rings.

52
00:01:59,348 --> 00:02:01,396
But if you wait, that ringing fades

53
00:02:01,396 --> 00:02:03,156
and fades and fades

54
00:02:03,156 --> 00:02:04,868
until you don't notice it anymore.

55
00:02:04,868 --> 00:02:07,476
Now that early universe was incredibly dense,

56
00:02:07,476 --> 00:02:09,655
like a metal, way denser,

57
00:02:09,655 --> 00:02:12,073
and if you hit it, it would ring,

58
00:02:12,073 --> 00:02:13,783
but the thing ringing would be

59
00:02:13,783 --> 00:02:15,911
the structure of spacetime itself,

60
00:02:15,911 --> 00:02:18,847
and the hammer would be quantum mechanics.

61
00:02:18,847 --> 00:02:20,888
What they found on Monday

62
00:02:20,888 --> 00:02:23,015
was evidence of the ringing

63
00:02:23,015 --> 00:02:25,335
of the spacetime of the early universe,

64
00:02:25,335 --> 00:02:27,440
what we call gravitational waves

65
00:02:27,440 --> 00:02:29,023
from the fundamental era,

66
00:02:29,023 --> 00:02:30,935
and here's how they found it.

67
00:02:30,935 --> 00:02:33,167
Those waves have long since faded.

68
00:02:33,167 --> 00:02:34,735
If you go for a walk,

69
00:02:34,735 --> 00:02:36,573
you don't wiggle.

70
00:02:36,573 --> 00:02:38,831
Those gravitational waves in the structures of space

71
00:02:38,831 --> 00:02:41,745
are totally invisible for all practical purposes.

72
00:02:41,745 --> 00:02:44,239
But early on, when the universe was making

73
00:02:44,239 --> 00:02:46,959
that last afterglow,

74
00:02:46,959 --> 00:02:48,687
the gravitational waves

75
00:02:48,687 --> 00:02:51,084
put little twists in the structure

76
00:02:51,084 --> 00:02:52,967
of the light that we see.

77
00:02:52,967 --> 00:02:55,983
So by looking at the night sky deeper and deeper

78
00:02:55,983 --> 00:02:58,591
—in fact, these guys spent
three years on the South Pole

79
00:02:58,591 --> 00:03:01,057
looking straight up through the coldest, clearest,

80
00:03:01,057 --> 00:03:03,007
cleanest air they possibly could find

81
00:03:03,007 --> 00:03:05,919
looking deep into the night sky and studying

82
00:03:05,919 --> 00:03:09,175
that glow and looking for the faint twists

83
00:03:09,175 --> 00:03:11,523
which are the symbol, the signal,

84
00:03:11,523 --> 00:03:13,343
of gravitational waves,

85
00:03:13,343 --> 00:03:15,684
the ringing of the early universe.

86
00:03:15,684 --> 00:03:17,471
And on Monday, they announced

87
00:03:17,471 --> 00:03:19,215
that they had found it.

88
00:03:19,215 --> 00:03:21,712
And the thing that's so spectacular about that to me

89
00:03:21,712 --> 00:03:24,580
is not just the ringing, though that is awesome.

90
00:03:24,580 --> 00:03:26,308
The thing that's totally amazing,

91
00:03:26,308 --> 00:03:28,012
the reason I'm on this stage, is because

92
00:03:28,012 --> 00:03:31,508
what that tells us is something
deep about the early universe.

93
00:03:31,508 --> 00:03:33,132
It tells us that we

94
00:03:33,132 --> 00:03:34,668
and everything we see around us

95
00:03:34,668 --> 00:03:37,372
are basically one large bubble

96
00:03:37,372 --> 00:03:39,128
—and this is the idea of inflation—

97
00:03:39,128 --> 00:03:43,027
one large bubble surrounded by something else.

98
00:03:43,027 --> 00:03:45,067
This isn't conclusive evidence for inflation,

99
00:03:45,067 --> 00:03:47,494
but anything that isn't inflation that explains this

100
00:03:47,494 --> 00:03:49,131
will look the same.

101
00:03:49,131 --> 00:03:50,586
This is a theory, an idea,

102
00:03:50,586 --> 00:03:52,035
that has been around for a while,

103
00:03:52,035 --> 00:03:53,635
and we never thought we we'd really see it.

104
00:03:53,635 --> 00:03:55,283
For good reasons, we thought we'd never see

105
00:03:55,283 --> 00:03:57,851
killer evidence, and this is killer evidence.

106
00:03:57,851 --> 00:03:59,531
But the really crazy idea

107
00:03:59,531 --> 00:04:02,363
is that our bubble is just one bubble

108
00:04:02,363 --> 00:04:06,699
in a much larger, roiling pot of universal stuff.

109
00:04:06,699 --> 00:04:08,995
We're never going to see the stuff outside,

110
00:04:08,995 --> 00:04:11,459
but by going to the South Pole
and spending three years

111
00:04:11,459 --> 00:04:14,219
looking at the detailed structure of the night sky,

112
00:04:14,219 --> 00:04:15,925
we can figure out

113
00:04:15,925 --> 00:04:18,675
that we're probably in a universe
that looks kind of like that.

114
00:04:18,675 --> 00:04:21,467
And that amazes me.

115
00:04:21,467 --> 00:04:23,643
Thanks a lot.

116
00:04:23,643 --> 00:04:25,589
(Applause)