- Posted 10.21.11
- NOVA
What are the chances that there are many other planets
in the universe as hospitable to intelligent life as ours? Peter Ward, a
paleontologist at the University of Washington and coauthor (with Don Brownlee)
of Rare Earth: Why Complex Life is Uncommon in the Universe, argues
that while simple life-forms like extremophiles can exist in harsh conditions,
complex life requires much more benign and stable conditions. As a result, Ward
believes that we are effectively alone in the universe.
Peter Ward is a paleontologist and professor of
Biology and of Earth and Space Sciences at the University of Washington. He is
the author of many popular works, including more than a dozen books. Ward is
currently researching the nature of the Cretaceous-Tertiary extinction event. EnlargePhoto credit: Courtesy Peter Ward/NASA
Interview of Peter Ward conducted in September 2011 and edited by Lauren Aguirre, Director of New Media for NOVA
ALONE OR JUST LONELY?
NOVA: What first got you
thinking about the possible existence of alien intelligence?
Peter Ward: Well, who isn't, actually? I mean, what
person really isn't thinking at least about ourselves and our aloneness or not?
We are so immersed in aliens, you can't get away from it. I would say that the
top four of the 10 greatest box office hits of all time were dealing with alien
life in some way or another. And somewhere along the line you have to start
asking yourself, well, what are the chances?
Don Brownlee and I started [working on the book] Rare
Earth sitting together at a lunch table. We knew each other, but barely. I
think the conversation started where I was saying, "Well, you know, I'm
just sick and tired of all the damn alien shows. [Finding aliens is] hardly
likely at all." And he said, "Really? I think the same thing."
And off it went.
NOVA: In Rare Earth you talk about
how we're very lonely in the universe. But lonely doesn't mean alone. Do you think
there probably is alien intelligence somewhere?
Peter Ward: Yeah. I think there absolutely has to be. The numbers
are just so great. In the first two billion years of the universe, you
certainly didn't have life, because you just had hydrogen and helium. That's a pretty
boring universe. But once we started building elements, you could have a little
more complex chemistry going on, organic chemistry, and then off it went. But
we're far enough along in this whole universe, it's highly probable. I would
say it's so probable that I don't see how you could bet against it.
Carl Sagan hit the nail on the head—"Billions and
billions," right? People made fun of him for that. But the reality is, he
was quite right. The numbers are so staggering: billions and billions of galaxies,
with billions and billions of stars. This was becoming close to the infinite
number of monkeys and typewriters.
"If there's no higher plant life, there's not
going to be higher animal life."
NOVA:You've said in your book
that for all intents and purposes, we're alone. But can you imagine a finding
that would really change the odds of finding alien intelligence?
Peter Ward: There is a very simple way, I think, to look for alien
intelligence. It requires the ability to image Earth-like planets. We'll be
there soon. Once you can image an Earth-like planet, all you need to do is
start looking in the spectrum for a really strong signal from mercury.
NOVA: From mercury?
Peter Ward:Yeah. If you think about it, how do we make
streetlights? They're all called mercury vapor lights. The strongest streetlights
in the world are made from one or two elements that actually give off a very
strong signal. Any engineer is going to settle on the same way of making a
light. There's not going to be some supernatural light out there.
You can pick up the spectral signal from our world
from a long way away. You've seen the pictures of the night side of the planet
covered with lights. That's going to send a very strong signal out there.
There's another simple way to figure out if a planet
is even worth looking at. And that is, what type of rivers does it have? Dave
Montgomery and I published a paper in Science in 2000. We pointed out that,
prior to the Devonian Period, there were no meandering rivers on Earth. There
was no Mississippi meandering across the floodplain. All rivers were braided,
because you can't have the normal rivers you find on Earth today without plants
for banks to be built.
This is pretty clear-cut in Washington State—trees go
away, the rivers change from meandering to braided streams. So just start
imaging the rivers on a planet, and you'll know if there's higher plant life or
not. If there's no higher plant life, there's not going to be higher animal
life.
THE MEDEA HYPOTHESIS
NOVA: Your book The Medea
Hypothesis, which proposes that life is inherently suicidal, suggests that
complex life doesn't last long. If true, what impact does this have on the
possibility of finding alien intelligence?
Peter Ward: Well, that's certainly what Don Brownlee thinks is the
most important part of the Drake equation. [The Drake Equation is used to estimate the number of detectable
extraterrestrial civilizations in the Milky Way.]
How long do complex
civilizations stay complex? We're going to come to that test here pretty
quickly in the next century or the next millennium. If we continue to increase
carbon dioxide, producing what I think will be a runaway sea-level rise, then
we're going to put this to the test. When you have too many people and no food
and civilization falls into chaos, how much civilization is retained? How long
will an intelligent species survive?
"Intelligence is the only way that you can stop
this whole process of life killing off life on the planet."
NOVA: Can you tell us more about
the Medea hypothesis and how that figures into the lifetime of an advanced
civilization?
Peter Ward: The only reason Medea came to my mind is that she was
chasing a very wayward life. [Editor's note: Medea is a figure in Greek
mythology who kills her own children by accident.] The fact that life seems to
screw everything up for itself over and over and over really negates the sort
of wonderful thought that Mother Earth is going to bail us out over and over.
Mother Earth doesn't bail us out. Life is a very complex phenomenon that's very
selfish, and it leads to population disasters over and over.
I argue that the only way out is intelligence.
Intelligence is the only way that you can stop this whole process of life
killing off life on the planet. Inevitably it's going to happen here. Carbon
dioxide is going to drop to the point that the planet can no longer produce
plant life. And then, 20 million years after that, the oxygen is gone and there
go the animals. So without us radically changing things really quickly, the
Earth becomes uninhabitable for complex life in a half a billion to a billion
years. That's all Medean.
NOVA: What do you think about the
idea that in another couple hundred years it won't be biological life, it'll be
synthetic life?
Peter Ward: Oh, I think it's coming. And interestingly, I just did
a whole day shoot for Morgan Freeman on the Through the Wormhole series just on
that particular question. For some reason, I seem to be pigeonholed with the
future evolution of humans. I wrote a paper about that in Scientific American,
and all of a sudden that's me. There are a lot of people who know a hell of a
lot more about it than I do. But I really do think that we're going to find
this synthesis of the machines and us.
THE RARE EARTH EQUATION
NOVA:In your version of the Drake
Equation, which you called the Rare Earth Equation, you replaced the factor
"communicating civilizations" with "complex metazoans." Why
complex metazoans and not communicating civilizations, or intelligent life?
Peter Ward: Well, we just wanted to up the ante. Every argument
has always been what is the percentage of planets that have complex
intelligent, communicating species? And we started out thinking about this, but
we wanted to separate it in our book. So we made it even simpler. What is the
percentage of planets with worms?
You know, there is going to be some fraction of the
planet with worms, where the worms finally evolve into human being-like
equivalents. But the odds against even getting worms, it occurred to us, was so
high that this would make our argument even stronger, which it did—the fact
that animals were tough to get to. And why is that? Well, to have animals, you
absolutely have to have oxygen. But it took more than two billion years to get
there.
"How can you get to be a complex civilization
without metal and electricity?"
NOVA: It doesn't seem like there
have been many people who've gone out on a limb and assigned a value to the
Drake Equation, or to the Rare Earth Equation. Have you?
Peter Ward: No. We always stayed away from that. Every once in a
while, every two or three years, we get a paper where somebody goes out on a
limb and tries it. We were never interested in trying to come up with an
absolute number. All we wanted to do was point out the conditions and the
problems to get there.
It's even starker than that. Let's say you had a water
world. Would those creatures ever communicate? How in the world would you ever
smelt metal underwater? How in the world could you ever produce electronics
underwater? I mean, we know what happens when you put water on electronics—it
shorts out because the electrons go everywhere.
How can you get to be a complex civilization without
metal and electricity? Maybe you could have these creatures in the opposite of
a scuba suit, where they're in water, right? They've got these little water
lumps walking around on the land, and they produce telescopes. But underwater
creatures are probably not going to have any sense of what the cosmos is, or
care.
THE EVOLUTION OF
INTELLIGENCE
NOVA: Do you think the evolution
of complexity is the natural order of things? Is that always going to happen?
Is intelligence always going to evolve?
Peter Ward: On the first question, complexity is already going to
happen if you get an advantage being complex. The advantage that takes place is
locomotion and movement. You cannot move rapidly or move at all, really, unless
you have multi-cellularity. And once you have that, to be able to move well you
need muscles. You need some sort of skeleton to thrust against.
So if any aspect of speed is better at finding food,
which it is, or escaping predators, which it often is, then that's going to
evolve. But intelligence, on the other hand—why weren't there intelligent
dinosaurs? Or why didn't intelligence come in the mammal-like reptiles? Or why
did it take the entire Cenozoic Era to get the primates with big brains?
Intelligence has a very high negative aspect to it.
Maintaining a big brain is a real problem for organisms. Nervous systems and
that much mass require so much oxygen that it's really a burden to the animal.
You only get as intelligent as you have to be. And for finding food, the big
cats, the big dogs, for 30 million years, they've been very good at it. And
there's been no reason for them to get better at it.
There were special circumstances and accidents that
created a world in which hominids could actually be pushed into high
intelligence. And the fact that it did not happen prior to this is just that
there aren't many body plans or many evolutionary scenarios where you need to
have brains our size.
"That's why I laugh when I see all these science
fiction stories about how we'll get even bigger heads. You know, no one talked
to the women about that!"
Is there a downside to being
intelligent aside from the cost of the food?
There's certainly a downside for childbearing because
obviously humans have an enormously high death rate in childbearing. Head size
and the female human pelvis were on a collision course. And we really were
walking a very thin knife-edge here. So many babies died in pre-civilization
childbirth that you had this strong evolutionary pressure to reduce head size
so you could have a greater longevity and a greater number of females
surviving.
That's why I laugh when I see all these science fiction stories
about how we'll get even bigger heads. You know, no one talked to the women
about that!
NOVA: Some people find the
suggestion that we're very lonely arrogant because it seems like yet another
example of humans believing we're special.
Peter Ward: We are special. I mean, we're certainly special in the
solar system. We're certainly special on Earth. You know, why not be special
and enjoy it? And why have a guilt feeling about it?
There is also the argument
that it's arrogant to think that intelligence like ours is pre-ordained. Are
these kinds of discussions what happens when there aren't enough data?
Oh yeah. And this is a case where there certainly
aren't enough data. But the really interesting thing that's been happening is
still the exoplanet searches. That's the greatest breakthrough in any of this
discussion in the last decade. Because even 10 years ago we really thought that
maybe planets were only present around 15 percent of stars.
In fact, the recent discovery of a planet orbiting a
multiple-star system, that really increases the odds. So yeah, there could be
tons of planets out there. The trouble is, we haven't found one Earth-like
planet yet.
SETI
NOVA:Do you think SETI, the
Search for Extraterrestrial Intelligence, is a futile search?
Peter Ward: No. I used to think so; it's such a long shot.
Personally, I don't think they'll ever find a signal anywhere. But as long as
there are people willing to fund it, and it doesn't cost the public anything,
why not? You've got really, really interesting people working away at it.
I had to laugh at that movie Contact, where Jodie
Foster plays this brilliant astronomer coming out of grad school who goes right
into SETI and gives up her position at Harvard. There's no reality to that.
Ph.D. astronomers now, they're not going into SETI. The people who go into SETI
are late-career people who've got nothing else to lose.
NOVA: Britain's Science Council
recently spent a year working on a new definition of science, which says that
"Science is the pursuit of knowledge and understanding of the natural and
social world, following a systematic methodology based on evidence." What
do you think of that definition? And how do you think the search for alien
intelligence fits into that?
Peter Ward: Well, I teach 250 people starting tomorrow, and my
first lecture is always, "What is science?" What I like to tell them
is that science is a verb, not a noun. They kind of look at me like,
"What?" It isn't just accumulated knowledge. It's the acquisition and
then using that knowledge. You never stand pat, because that isn't science.
That's just an encyclopedia.
"We don't go to lunch and talk about, 'Well, what
do you think about the chances for intelligence today?'"
NOVA:What about SETI? Is it
predictive?
Peter Ward: The way SETI is predictive is that it takes into
account the findings from astronomy, exoplanets, planetology, all that stuff.
SETI has to take into account all that knowledge so that they can target. They
don't want to target everything. They want to go for the stars with the highest
probability. Well, how do they know which ones those are? That comes from all
the various disciplines and a whole giant knowledge set.
We don't yet know enough about the conditions
necessary to keep complex life alive for a long time. We're still working on
that, and that will help SETI. And there's no reason that SETI has to die out
in the next 50 years. We're in this for the long haul. We humans are going to
be here for a long time. Maybe SETI, a thousand years from now, has so refined
the search that they've increased their instrumentation that they finally do
find something way out there.
NOVA:At the end of the day it
seems like the question of the existence of extraterrestrial intelligence is
not if but how many. Do you agree?
Peter Ward: Every reasonable person I've talked with, once they
know the numbers, give it a probability. It's never yes or no. It's just
"the chances are." That's about as far as it goes. People don't talk
about it that much. And we don't go to lunch and talk about, "Well, what
do you think about the chances for intelligence today?" It just doesn't come
up, because it's non-retrievable from a scientific point of view right now.
Other than SETI, it doesn't seem worth anybody's while. There are other things
to worry about, like funding.
Interview of Peter Ward conducted in September 2011
and edited by Lauren Aguirre, Director of New Media for NOVA
No comments:
Post a Comment