ABOUT THE SPEAKER
Enrico Ramirez-Ruiz - Astrophyscist, stellar mortician
Looking not at the heavens but at computer models, Enrico Ramirez-Ruiz studies some of the most powerful explosions since the birth of the universe.

Why you should listen

Enrico Ramirez-Ruiz is eager to understand our origins and, in some cases, is simply wild about things that go bang in the night sky. He works with computer models to understand the cataclysmic death of stars and recently led efforts to uncover the origin of the heaviest, most neutron-rich elements in the universe, like gold and uranium. Ramirez-Ruiz tests out his theories with complex computer simulations that defy the boundaries of human experience and the assumptions we make about the universe.

Ramirez-Ruiz was born in Mexico, studied physics at the Universidad Nacional Autónoma de México, and pursued his PhD at Cambridge  University. He was the John Bahcall Fellow at the Institute for Advanced Study at Princeton before joining the faculty at UCSC, where he is a professor of astrophysics and astronomy. He has received awards from the American Physical Society, the American Astronomical Society, the David and Lucile Packard Foundation, Mexcian Academy of Sciences and the Radcliffe Institute for Advanced Study at Harvard University, and he is the Niels Bohr Professor at the University of Copenhagen, funded by the  Danish National Research Foundation. Ramirez-Ruiz is the inaugural holder of the Vera Rubin Presidential Chair for Diversity in Astronomy, which was in part funded by the Heising-Simons Foundation.

More profile about the speaker
Enrico Ramirez-Ruiz | Speaker | TED.com
TED@NAS

Enrico Ramirez-Ruiz: Your body was forged in the spectacular death of stars

Filmed:
1,213,570 views

We are all connected by the spectacular birth, death and rebirth of stars, says astrophysicist Enrico Ramirez-Ruiz. Journey through the cosmic history of the universe as Ramirez-Ruiz explains how supernovas forged the elements of life to create everything from the air you breathe to the very atoms that make you.
- Astrophyscist, stellar mortician
Looking not at the heavens but at computer models, Enrico Ramirez-Ruiz studies some of the most powerful explosions since the birth of the universe. Full bio

Double-click the English transcript below to play the video.

00:13
We are all atomically connected.
0
1714
2817
00:16
Fundamentally, universally.
1
4913
2951
00:19
But what does that mean?
2
7888
1601
00:22
I'm an astrophysicist, and as such,
3
10673
2952
00:25
it is my responsibility to trace
the cosmic history
4
13649
4035
00:29
of every single one of your atoms.
5
17708
2805
00:33
In fact, I would say
6
21394
2219
00:35
that one of the greatest achievements
of modern astronomy
7
23637
3559
00:39
is the understanding of how our atoms
were actually put together.
8
27220
5166
00:45
While hydrogen and helium were made
9
33823
2841
00:48
during the first two minutes
of the big bang,
10
36688
3072
00:51
the origin of heavy elements,
11
39784
2396
00:54
such as the iron in your blood,
the oxygen we're breathing,
12
42204
4310
00:58
the silicone in your computers,
13
46538
2285
01:00
lies in the life cycle of stars.
14
48847
3135
01:05
Nuclear reactions take lighter elements
and transform them into heavier ones,
15
53388
6023
01:11
and that causes stars to shine
16
59435
2508
01:13
and ultimately explode,
17
61967
2093
01:16
therefore enriching the universe
with these heavy elements.
18
64084
5413
01:21
So without stellar death
19
69966
4258
01:27
there would be no oxygen
20
75101
2190
01:29
or other elements
heavier than hydrogen and helium,
21
77315
3571
01:32
and therefore, there would be no life.
22
80910
2526
01:36
There are more atoms in our bodies
23
84149
3556
01:39
than stars in the universe.
24
87729
1944
01:42
And these atoms are extremely durable.
25
90642
2533
01:45
The origins of our atoms
26
93737
2167
01:47
can be traceable to stars
that manufactured them in their interiors
27
95928
5357
01:53
and exploded them
all across the Milky Way,
28
101309
4221
01:57
billions of years ago.
29
105554
1984
02:00
And I should know this,
30
108006
1428
02:01
because I am indeed a certified
stellar mortician.
31
109458
3124
02:04
(Laughter)
32
112884
1479
02:06
And today, I want to take you on a journey
that starts in a supernova explosion
33
114387
5746
02:12
and ends with the air
that we're breathing right now.
34
120157
3570
02:18
So what is our body made of?
35
126578
1867
02:21
Ninety-six percent
consists of only four elements:
36
129189
5662
02:27
hydrogen, carbon, oxygen and nitrogen.
37
135490
3958
02:33
Now the main character
of this cosmic tale is oxygen.
38
141220
4333
02:39
Not only is the vast majority
of our bodies made of oxygen,
39
147061
4731
02:43
but oxygen is the one element
fighting to protect life on earth.
40
151816
4706
02:49
The vast majority of oxygen
in the universe
41
157490
2365
02:51
was indeed produced
over the entire history of the universe
42
159879
5047
02:56
in these supernova explosions.
43
164950
2000
02:59
These supernova explosions
signal the demise of very massive stars.
44
167760
4690
03:04
And for a brilliant month,
45
172474
2333
03:06
one supernova explosion
can be brighter than an entire galaxy
46
174831
4175
03:11
containing billions of stars.
47
179030
2412
03:13
That is truly remarkable.
48
181823
1667
03:17
That is because massive stars
burn brighter
49
185046
4880
03:21
and have a spectacular death,
compared to other stars.
50
189950
3952
03:26
Nuclear fusion is really
the lifeblood of all stars,
51
194728
3516
03:30
including the sun,
52
198268
1599
03:31
and as a result is the root source
of all the energy on earth.
53
199891
4444
03:37
You can think of stars
as these fusion factories
54
205724
4313
03:42
which are powered
by smashing atoms together
55
210061
2945
03:45
in their hot and dense interiors.
56
213030
2309
03:47
Now, stars like our sun,
57
215641
2555
03:50
which are relatively small,
58
218220
1484
03:51
burn hydrogen into helium,
59
219728
2214
03:53
but heavier stars of about
eight times the mass of the sun
60
221966
3785
03:57
continue this burning cycle
61
225775
2476
04:00
even after they exhausted
their helium in their cores.
62
228275
3649
04:05
So at this point,
63
233386
1882
04:07
the massive star
is left with a carbon core,
64
235292
3166
04:10
which, as you know,
is the building block of life.
65
238482
3186
04:14
This carbon core continues to collapse
66
242784
3730
04:18
and as a result,
the temperature increases,
67
246538
2507
04:21
which allows further
nuclear reactions to take place,
68
249069
3954
04:25
and carbon then burns into oxygen,
69
253047
2628
04:27
into neon, silicon, sulphur
70
255699
3666
04:31
and ultimately iron.
71
259389
1619
04:33
And iron is the end.
72
261667
1864
04:36
Why?
73
264569
1150
04:37
Because iron is the most
bound nuclei in the universe,
74
265743
2535
04:40
which means that we cannot
extract energy by burning iron.
75
268302
4401
04:45
So when the entire core
of the massive star is made of iron,
76
273268
5658
04:50
it's run out of fuel.
77
278950
1400
04:52
And that's an incredibly
bad day for a star.
78
280871
3135
04:56
(Laughter)
79
284030
3626
05:00
Without fuel, it cannot generate heat,
80
288395
2787
05:04
and therefore gravity has won the battle.
81
292434
2800
05:08
The iron core has no other choice
but to collapse,
82
296228
3722
05:11
reaching incredibly high densities.
83
299974
2825
05:15
Think of 300 million tons
84
303363
3293
05:18
reduced to a space
the size of a sugar cube.
85
306680
3000
05:22
At these extreme high densities,
the core actually resists collapse,
86
310458
4609
05:27
and as a result,
87
315091
1595
05:28
all of this infalling material
bounces off the core.
88
316710
3888
05:33
And this dramatic bounce,
89
321551
1265
05:34
which happens in a fraction
of a second or so,
90
322840
3967
05:38
is responsible for ejecting
the rest of the star in all directions,
91
326831
5833
05:44
ultimately forming a supernova explosion.
92
332688
2734
05:50
So, sadly, from the perspective
of an astrophysicist,
93
338450
5230
05:55
the conditions in the centers
of these exploding stars
94
343704
3399
05:59
cannot be recreated in a laboratory.
95
347127
2283
06:01
(Laughter)
96
349434
1008
06:02
Now, thankfully for humanity,
we're not able to do that.
97
350466
3619
06:06
(Laughter)
98
354109
1706
06:07
But what does that mean?
99
355839
1223
06:09
That means that as astrophysicists,
100
357086
1682
06:10
we have to rely on sophisticated
computer simulations
101
358792
4360
06:15
in order to understand
these complex phenomena.
102
363176
3793
06:20
These simulations can be used
to really understand how gas behaves
103
368358
3796
06:24
under such extreme conditions.
104
372178
1947
06:27
And can be used to answer
fundamental questions
105
375168
2253
06:29
like, "What ultimately disrupted
the massive star?"
106
377445
3175
06:32
"How is it that this implosion
can be reversed into an explosion?"
107
380644
4071
06:39
There's a huge amount
of debate in the field,
108
387580
2468
06:42
but we all agree that neutrinos,
109
390072
4434
06:46
which are these elusive
elementary particles,
110
394530
2808
06:49
play a crucial role.
111
397362
1516
06:51
Yeah?
112
399873
1165
06:53
I'm about to show you
one of those simulations.
113
401062
2953
06:58
So neutrinos are produced in huge numbers
once the core collapses.
114
406509
5650
07:04
And in fact,
115
412183
1171
07:05
they are responsible for transferring
the energy in this core.
116
413378
3683
07:09
Like thermal radiation in a heater,
117
417696
2611
07:12
neutrinos pump energy into the core,
118
420331
3548
07:15
increasing the possibility
of disrupting the star.
119
423903
4412
07:20
In fact, for about a fraction of a second,
120
428784
2761
07:23
neutrinos pump so much energy
121
431569
1627
07:25
that the pressure increases high enough
that a shock wave is produced
122
433220
4680
07:29
and the shock wave
goes and disrupts the entire star.
123
437924
3712
07:34
And it is in that shock wave
where elements are produced.
124
442006
4278
07:40
So thank you, neutrinos.
125
448243
1715
07:41
(Laughter)
126
449982
1595
07:45
Supernovas shine bright,
127
453132
3087
07:48
and for a brief period of time,
128
456243
2191
07:50
they radiate more energy
than the sun will in its entire lifetime.
129
458458
5042
07:56
That point of light that you see there,
130
464852
2707
07:59
which was certainly not there before,
131
467583
3301
08:02
burns like a beacon,
132
470908
2286
08:05
clearly indicating the position
where the massive star has died.
133
473218
3898
08:11
In a galaxy like our own Milky Way,
134
479196
2651
08:13
we estimate that about
once every 50 years,
135
481871
3912
08:17
a massive star dies.
136
485807
1778
08:20
This implies that somewhere
in the universe,
137
488696
3001
08:23
there's a supernova explosion
every second or so.
138
491721
3431
08:29
And thankfully for astronomers,
139
497460
2262
08:31
some of them are actually found
relatively close to earth.
140
499746
3341
08:36
Various civilizations
recorded these supernova explosions
141
504363
5659
08:42
long before the telescope was invented.
142
510046
2963
08:46
The most famous of all of them
143
514699
2197
08:48
is probably the supernova explosion
that gave rise to the Crab Nebula.
144
516920
3688
08:53
Yeah?
145
521746
1268
08:55
Korean and Chinese astronomers
recorded this supernova in 1054,
146
523038
6055
09:01
as did, almost certainly,
Native Americans.
147
529117
2683
09:05
This supernova happened
about 5,600 light-years away from earth.
148
533372
5260
09:11
And it was so incredibly bright
149
539205
2198
09:13
that astronomers could see it
during the day.
150
541427
2509
09:16
And it was visible to the naked eye
for about two years in the night sky.
151
544651
4848
09:25
Fast forward 1,000 years or so later,
and what do we see?
152
553278
4363
09:30
We see these filaments
that were blasted by the explosion,
153
558062
4111
09:34
moving at 300 miles per second.
154
562197
2516
09:37
These filaments are essential
for us to understand
155
565133
4174
09:41
how massive stars die.
156
569331
1933
09:43
The image that you see there
157
571752
1365
09:45
was assembled
by the Hubble Space Telescope
158
573141
2444
09:47
over a span of three months.
159
575609
1867
09:49
And it is incredibly important
to astronomers
160
577990
2272
09:52
because it ultimately carries
the chemical legacy
161
580286
3188
09:55
of the star that exploded.
162
583498
1733
09:57
The orange filaments that you see there
are the tattered remains of the star,
163
585760
5073
10:02
and are made primarily of hydrogen,
164
590857
2333
10:05
while the blue and red
filaments that you see
165
593634
3183
10:08
are the freshly synthesized oxygen.
166
596841
2489
10:11
So studying supernova remnants,
like the Crab Nebula,
167
599746
4444
10:16
allowed astronomers to firmly conclude
168
604214
2294
10:18
that the vast majority of oxygen on earth
was produced by supernova explosions
169
606532
5443
10:23
over the history of the universe.
170
611999
2200
10:27
And we can estimate
171
615117
1516
10:28
that in order to assemble
all the atoms of oxygen in our body,
172
616657
4443
10:33
it took on the order
of a 100 million supernova.
173
621124
3268
10:37
So every bit of you,
or at least the majority of it,
174
625151
3992
10:41
came from one of these
supernova explosions.
175
629167
2795
10:47
So now you may be wondering,
176
635268
1595
10:48
how is it that these atoms
177
636887
2000
10:50
that were generated in such
extreme conditions
178
638911
4753
10:55
ultimately took residence in our body?
179
643688
2534
10:59
So I want you to follow
the thought experiment.
180
647212
3869
11:03
Imagine that we're in the Milky Way,
and a supernova happens.
181
651105
3495
11:06
It blasted tons and tons of oxygen atoms
182
654998
3897
11:10
almost into empty space.
183
658919
2309
11:14
A few of them were able
to be assembled in a cloud.
184
662085
4071
11:19
Now, 4.5 billion years ago,
185
667292
3285
11:22
something unsettled that cloud
and caused it to collapse,
186
670601
3468
11:26
forming the sun in its center
and the solar system.
187
674093
4301
11:32
So the sun, the planets and life on earth
188
680216
3603
11:35
depend on this beautiful cycle
189
683843
2564
11:38
of stellar birth, stellar death
and stellar rebirth.
190
686431
4849
11:43
And this continues the recycling
of atoms in the universe.
191
691875
4730
11:48
And as a result, astronomy
and chemistry are intimately connected.
192
696629
3986
11:53
We are life forms that have evolved
to inhale the waste products of plants.
193
701815
6809
12:01
But now you know
194
709292
1230
12:02
that we also inhale the waste products
of supernova explosions.
195
710546
3174
12:05
(Laughter)
196
713744
1698
12:08
So take a moment, inhale.
197
716990
2000
12:12
An oxygen atom
has just gone into your body.
198
720228
2959
12:15
It is certain that that oxygen [atom]
199
723211
2327
12:17
remembers that it was
in the interior of a star
200
725562
2237
12:19
and it was probably manufactured
by a supernova explosion.
201
727823
3373
12:24
This atom may have traveled
the entire solar system
202
732220
4000
12:28
until it splashed on earth,
203
736244
2254
12:30
long before reaching you.
204
738522
1983
12:34
When we breathe,
205
742442
1261
12:36
we use hundreds of liters
of oxygen every day.
206
744982
4795
12:43
So I'm incredibly lucky to be standing
in front of this beautiful audience,
207
751566
5024
12:48
but I'm actually stealing
your oxygen atoms.
208
756614
3238
12:51
(Laughter)
209
759876
2529
12:54
And because I'm speaking to you,
210
762429
1532
12:55
I'm giving you some of them back,
that once resided in me.
211
763985
3563
13:03
So breathing, yeah,
212
771276
4736
13:08
participates in this
beautiful exchange of atoms.
213
776036
4089
13:12
And you can then ask,
214
780149
1861
13:15
"Well, how many atoms in our body
once belonged to Frida Kahlo?"
215
783887
7000
13:23
(Laughter)
216
791013
2390
13:25
About 100,000 of them.
217
793427
1872
13:28
100,000 more probably
belonged to Marie Curie,
218
796339
4429
13:32
100,000 more to Sally Ride,
219
800792
2388
13:35
or whoever you want to think of.
220
803204
2134
13:39
So breathing is not only filling our lungs
with cosmic history,
221
807236
6789
13:46
but with human history.
222
814510
1428
13:49
I would like to end my talk
by sharing a myth
223
817696
2979
13:52
that is very close to my heart.
224
820699
1801
13:54
A myth from the Chichimeca culture,
225
822524
2365
13:56
which is a very powerful
Mesoamerican culture.
226
824913
3008
14:01
And the Chichimecas believe
227
829001
2200
14:03
that our essence
was assembled in the heavens.
228
831225
3400
14:06
And on its journey towards us,
229
834649
2166
14:08
it actually fragmented
into tons of different pieces.
230
836839
3598
14:13
So my abuelo used to say,
231
841445
1563
14:15
"One of the reasons you feel incomplete
232
843032
2722
14:17
is because you are missing your pieces."
233
845778
2221
14:20
(Laughter)
234
848023
1019
14:21
"But don't be fooled by that.
235
849066
1575
14:22
You've been given an incredible
opportunity of growth.
236
850665
3745
14:26
Why?
237
854434
1151
14:27
Because it's not like those pieces
were scattered on earth
238
855609
2754
14:30
and you have to go and pick them up.
239
858387
1762
14:32
No, those pieces fell into other people.
240
860173
2666
14:35
And only by sharing them
you will become more complete.
241
863489
3530
14:40
Yes, during your life,
242
868021
1167
14:41
there's going to be individuals
that have these huge pieces
243
869212
2822
14:44
that make you feel whole.
244
872058
1566
14:47
But in your quest of being complete,
245
875355
2905
14:50
you have to treasure and share
every single one of those pieces."
246
878284
5023
14:57
Sounds a lot like the story
of oxygen to me.
247
885391
3090
15:00
(Laughter)
248
888505
1045
15:01
Which started in the heavens
in a supernova explosion,
249
889574
3254
15:04
and continues today,
250
892852
2447
15:08
within the confines of our humanity.
251
896061
2400
15:11
Our atoms in our body
have embarked on an epic odyssey,
252
899911
5261
15:17
with time spans from billions of years
to mere centuries,
253
905196
5119
15:22
all leading to you,
254
910339
2389
15:24
all of you,
255
912752
1692
15:26
witnesses of the universe.
256
914468
1873
15:28
Thank you.
257
916365
1159
15:29
(Applause)
258
917548
3529
Translated by Ivana Korom
Reviewed by Krystian Aparta

▲Back to top

ABOUT THE SPEAKER
Enrico Ramirez-Ruiz - Astrophyscist, stellar mortician
Looking not at the heavens but at computer models, Enrico Ramirez-Ruiz studies some of the most powerful explosions since the birth of the universe.

Why you should listen

Enrico Ramirez-Ruiz is eager to understand our origins and, in some cases, is simply wild about things that go bang in the night sky. He works with computer models to understand the cataclysmic death of stars and recently led efforts to uncover the origin of the heaviest, most neutron-rich elements in the universe, like gold and uranium. Ramirez-Ruiz tests out his theories with complex computer simulations that defy the boundaries of human experience and the assumptions we make about the universe.

Ramirez-Ruiz was born in Mexico, studied physics at the Universidad Nacional Autónoma de México, and pursued his PhD at Cambridge  University. He was the John Bahcall Fellow at the Institute for Advanced Study at Princeton before joining the faculty at UCSC, where he is a professor of astrophysics and astronomy. He has received awards from the American Physical Society, the American Astronomical Society, the David and Lucile Packard Foundation, Mexcian Academy of Sciences and the Radcliffe Institute for Advanced Study at Harvard University, and he is the Niels Bohr Professor at the University of Copenhagen, funded by the  Danish National Research Foundation. Ramirez-Ruiz is the inaugural holder of the Vera Rubin Presidential Chair for Diversity in Astronomy, which was in part funded by the Heising-Simons Foundation.

More profile about the speaker
Enrico Ramirez-Ruiz | Speaker | TED.com