Transcript

Cosmic collisions and dinosaurs: Adriana Ocampo at TEDXPuraVida

Translator: Jaime Ochoa
Reviewer: Sebastian Betti I wanted to start by inviting you
to travel on a virtual spacecraft, this spacecraft will take us
to explore the intergalactic and also interstellar
and interplanetary medium. Our copilot will be my avatar,
let me introduce him. His name is Dino, so having said that,
let's begin our space adventure. Cosmic collisions played a key role in the formation of the solar system
and of everything around us; and the dinosaurs have left us
some very interesting lessons. Our voyage starts in our galaxy,
called the Milky Way, 4 billion years ago, and here we start taking a look
at the beautiful spiral galaxy which is where our solar system is nestled. And as we travel towards it, we enter its core,
the central part of the galaxy where a sigma relation or black hole lives. We move on exploring these traces that have been left
by massive explosions of stars in which the heavy elements that
we find on the Earth today were formed; and which, in turn, originated life. In one of the external "arms" of our galaxy we find a very young solar system with a very young star
that today we call the Sun. As you can see, there is no planet
orbiting the Sun star, yet, around this young star. But maybe if we could dim the lights you could see a little better here, these asteroid fragments which 
are full of the primitive elements that originated the planets. But, how were the planets formed? We can see here all these fragments, the traces, started to collide in cosmic collisions between one another, emitting
a lot of energy in the form of heat; and we see how they are
accreting among themselves and that's how the planetary
cores begin to form. It's worth noticing that the great
gas planets in our solar system like Jupiter, Saturn, Uranus, and Neptune instead of having asteroids
like these in their nuclei, they are formed by comets. Each one of these orange spots
that we can see here are the imprints left
by these asteroid impacts that caused and created the craters. We begin to see the formation
of a proto-planet, in our case, it is our Earth. But, beware! In our virtual space window another proto-planet is approaching, and it is almost the size of Mars. We see this huge collision. This collision, which occurred
4 billion years ago, was the one that ripped off
these fragments that -- a fragment of the Earth
caused the formation of our natural satellite, the moon. So the moon is an Earth fragment. And the moon played a very important role because, as we will see,
it balanced the Earth system. Again, here we can see the Earth
in a younger shape still without oceans as you can see,
neither oceans nor atmosphere, and a very young moon
that also begins to orbit it. Eventually it is going to establish
a balance in the system and this is very important
so that life on Earth can appear. Here, it is already cooling down. OK, but as I told you, I'd like to give my avatar,
Dino, a chance to tell us a little about the comets. What role did the comets play? Probably, the comets were the ones
who brought life to Earth and started to scatter it in the oceans. I leave you here with Dino, my avatar. Dino: You know Adriana, here is where
it gets interesting. The Earth is warm and the comets
bring the water that fills the oceans. We have all the necessary ingredients
to support life; like water, heat, and the Sun. Adriana: As Dino points out,
the planets played a key role because they not only had
the organic material but even had the amino acids that probably
originated life and the oceans as they hit the Earth, and finally they formed this beautiful 
blue planet as we have it today. Well, let's move forward in time. Our spaceship not only helps us
travel through space but can also help us
move forward in time to an important date in our planet's 
geological history, 65 million years ago, when something incredible happened;
the so-called Kretaceous/Tertiary boundary. Dino is going to tell us
how our planet looked back then. Dino: This was my bar. Hi Rick, how are you? Adriana, we were big
and dominated this place. We were clever, strong,
we had teeth. Being at the top of the food chain we were above all the species 
and no one threatened us. Those were the good old days.
Oh, yeah! Those were the days. Adriana: Our Dino, is reminiscing 
when the Earth was a warmer place. 65 million years ago, its atmosphere
was richer in oxygen. But something is about to happen that completely changed
the scheme of life on the planet. If we could dim the lights, please. Here, in our window, we can see
what is going to happen. Dino: But all of that changed when 
a rock from space fell on our planet. This complicated things for us. The impact blew so much dust and debris 
in the air that they blocked the Sun. Plants died and the herbivorous 
started starving to death and since we ate them, 
we were also starving. This lasted for a long time 
and the dinosaurs perished. Adriana: There were tsunamis, 
global tsunamis. There were huge global fires
and the planet was set ablaze when the ash fell after the impact of the
10km-wide asteroid. Many places became deserts. Our planet grew completely 
dark for over six months and a great number of
sulfuric acid clouds formed, we will see later
why this was important, to such an extent that our planet turned
into a modern day Venus, completely hazy as we can see here. We can't see its surface; that means that the 
solar energy never reached its surface. This event is called the mass extinction
of the Kretaceous/Tertiary, 65 million years ago. It is worth mentioning that
in this mass extinction over 50 percent of the species
in the oceans disappeared but in the continents only 20 percent. In 1980, a research team
from Berkeley, father and son, suggested something very controversial. They said that the reason why
the dinosaurs had gone extinct was because a 10km-wide asteroid hit the Earth, changing
the biosphere completely. But then, what was
their most conclusive evidence? They found it in a layer
of ground in Italy that contained a great
concentration of iridium. Iridium is an element that is found in great 
quantities in comets and asteroids and that's why they related this evidence
to the extraterrestrial impact. This theory was extremely controversial
because the crater had not been discovered. This was the imprint of the impact, 
this cosmic collision must have left. There were impacts on the moon
and Mars but, what about the Earth? Scientists started looking for the great
crater left after the K/T impact. There are over 160 collision structures
discovered and confirmed on the Earth but the one corresponding to the 
K/T had not been discovered, until --and here is where
the story gets interesting, because now we start seeing the evidence
for this detective and scientific story. There are three important lines of evidence:
Iridium, the quartz collision, and tektite. These were the evidence that was found first before the crater impact was discovered. The iridium oddities were found
all over the planet and, as I mentioned, iridium comes from 
the asteroids and comets in the amounts that were found in that Kretaceous/Tertiary boundary. They were then also found scattered
all around the planet. This is called quartz grain collision, they are grains of sand
that have been exposed to high pressures so that
they are deformed in this way, this being an indicator of the impact. And finally, these granules
or glass beads were also found scattered around the planet,
where we knew that was the chemical composition
where the asteroid impacted. We had these confirmations but we 
did not know where the asteroid was. Then in 1988, I was working
with a team of archaeologists, using satellite images and we found what we could see here,
in the Yucatan Peninsula, something quite interesting,
as we can see in this white square. If we zoom into it, we can see that
this is the Yucatan Peninsula. We began to spot these black spots
or "cenotes" [sinkholes] and these sinkholes formed an arch, 
a perfect circle; but why? It tourned out, as we would publish in 1991, more than 10 years later after
the Alvarez's hypothesis, that the collision crater that caused the extinction
of the dinosaurs in the K/T was located in the Yucatan Peninsula, it was then named the Chicxulub crater. But then we started to wonder
about the great amount of sulfuric acid; where did these clouds come from? They came from the crater's underground. The Yucatan peninsula
is very rich in sulfur and that was the key mechanism that
lasted over a decade, over twelve years. It caused a great frozen state and later a warming
and a greenhouse effect. Looking for more evidence, I had the chance
to take part on several scientific expeditions that took me to Belize
in order to find them, and ... with those evidences we could confirm 
the Chicxulub crater collision hypothesis which stated the cause for
the massive extinction. But we know through the geological record of the planet,
that there have been five mass extinctions. Let's see why the last extinction
is the most interesting one. Dino: Adriana, if that rock from outer space
had never fallen on our planet nowadays, things around us
would look very differently. Imagine Adriana, think about this: If we were still at the top of the food chain,
you would look a little differently. You would have skin just like mine,
your arms would be shorter, your eyes would be more attractive,
your teeth would be more useful. Here you are, Adriana.
Much better. Adriana: What would you think
if we looked like this? Honestly, the dinosaur lessons on the massive extinction of the dinosaurs have been very important:
We know we don't live on an island, our planet is part of
a very dynamic and changing system located in a galaxy
in an universe that is evolving. And everyone,
all of you, are astronauts and our spaceship
is called the Earth. So, take care of it.
Thank you very much. (Applause)