[ Music ] [ Silence ] [ Applause ] >> Well, thank you, Ann,
for that kind introduction. Ladies and gentlemen,
good morning [inaudible]. It's great for me to be back
here in Sydney Upper House. It's also great for me to catch up with my colleague,
Lawrence Kraut. We have adjacent offices at
Arizona State University, but we both travelled so much that we're often
not there together. So it's nice to be in
the same place for once. Now, a pivotal event in the
history of science occurred in the year 1859, with the
publication by Charles Darwin of his famous book,
"The Origin of Species". And in his book, Darwin gave
a convincing account of how over billions of years,
life on Earth had evolved from simple microbes to
the richness and complexity of the biosphere
that we see today. But he pointedly left out of account how life got
going in the first place. "It is mere rubbish," he
said, "thinking of present of the origin of life. One might as well think
of the origin of matter." Well, I'm pleased to say that
we physicists have explained the origin of matter;
Lawrence mentioned that. And the question is
how we are getting on explaining the
origin of life? Well, I have to say that a
century and a half later, we are still largely in the
dark about life's origin. Now, the problem of life's
origin is really three problems rolled into one. There's the when, the
where, and the how. And I'll talk about
each of these in turn. First of all, when
did life begin? Now, we can't say
exactly when it began, but what we can do is trace
the fossil record back in time to the earliest point where we
can be fairly sure, that is, we look for the oldest
traces of life on Earth. And it turns out that those
oldest traces are found right here in Australia. Well, not quite here, but on
the other side of Australia, or the Pilbara region;
that's near Port Hedland. And in that region, there
are rocks that are sticking out of the hillside, which
are three-and-a-half billion years old. So they're among the
oldest known rocks on Earth. And those rocks contain what
is probably the oldest traces of life on Earth for
the generally-agreed. There's some dispute that are
rocks a bit older than that, but there's some dispute about whether the traces
of life are genuine. But those particular rocks,
we're pretty much agreed, do contain evidence for life. But this evidence is
in an indirect form. So I took a travel to go there
back in my moustache days, [laughter] and it's best
not to go in the summer. It's actually very hot in
that part of Australia. And this is what the
scientists get excited about, this rock here; it's
called "chert". And if you look carefully
in that chert, what you see are
these little features, they're like ice cream
cones nested together and sliced through. Now, I have to say that doesn't
look very exciting to me, but the astrobiologists -- they're the people who
study life in the universe, they get very excited
by these features, which have the name
"stromatolites". Now, true technically,
they're not stromatolites, they're fossilised
stromatolites, three-and-a-half-billion-year
old structures. And they're not themselves -- were never themselves
living things. They're fossils of
microbial mats, so microbes that
deposited sediment in layers over many thousands of years, and then these things
became fossilised and embedded in the rocks. And that's what gets
them excited. Now, you might say, "Well,
show me a living stromatolite." They're very rare. It's hard to find
stromatolites, but you can. If you're visiting the Pilbara
Region, I do recommend it. Then a couple of days' drive
from there, you go to Shark Bay, and there you see
living stromatolites. [Laughter] And you see -- what I like to say is
if you imagine getting in a time machine and going back
three-and-a-half billion years on Earth, this is
as good as it gets. You know, this is life on Earth. That's about all you see. It's really, really boring. So it took a long
time for life on Earth to evolve the complex
structures like us. In fact, for about two billion
years, there wasn't much to see. And so it's not very exciting, but it's tremendously
significant that we see fossils of structures like this in
these very ancient rocks. So it looks like life
was established on Earth, quite firmly, three-and-a-half
billion years ago. Now, let's put that
into context. The Earth itself, the
solar system indeed, is four-and-a-half -- little over four-and-a-half
billion years old. And of course, it
didn't formed overnight. The planets form from a
swirling disc of gas and dust around the protosun, and it
took really quite some hundreds of millions of years for
this process to be completed. And during that time, huge
chunks of material rained down on the newly-formed planet. So this is a NASA
depiction of this process; and here's another one. We can imagine the early Earth
being bombarded ferociously -- [inaudible] all of the early
planets bombarded ferociously by huge comets, and
asteroids, and rocky bodies. Now, I'm sure everyone's
familiar with the fact that the dinosaurs were probably
done in by a comet that smashed into Earth about 65 million
years ago and created a crater about 180 kilometres across in
what is now northern Mexico. Well, that was small-scale
stuff compared to what was going on in the early time
in the solar system. The biggest of these impactors
would have had enough energy to boil the oceans dry,
and sway their planet with incandescent rock vapour. And so this is an artist
depiction of this sort of hell on Earth that would
have persisted -- it's a little hard to
know, but certainly for some hundreds of
millions of years. And in fact, the best record of
this early bombardment comes not from Earth itself, because
the material gets reprocessed, but from the moon. And on the moon, all those
craters that are so familiar, tell us something about the
early heavy bombardment. And if you put some
sort of schematic graph, what you find is that
this bombardment abated around about 3.8 billion years
ago, whereas as I've told you, life on Earth extends
back through 3.5. Of course, it didn't
appear overnight, so presumably back to, you know,
at least 3.6 billion years ago. And so this is a
very narrow window. In fact, Carl Sagan many years
ago said that life must be easy to get going, because no
sooner was Earth ready for it than up it popped. Turns out that that
argument is fallacious. It might be right, but
it doesn't have to be. So I'll come back to that. But the important point is
that there's been life on Earth for almost the entire duration
of when Earth has been habited. Okay; let me come
onto the where part. Where exactly did life start? [ Silence ] Well, I mention that
Darwin wouldn't be drawn on the subject of life's origin. But in an effort to
refrain, he did speculate about what he called a "warm
little pond" over which over many millions of
years chemicals might leach out of the rocks, and
by some sort of process of chemical self-assembly, more and more complex
molecules might form, until eventually
something would crawl out of this warm little pond. And that's as far as
he would be drawn. But it did give rise to the
popular notion of some sort of primordial soup, at
least an aqueous medium in which some sort of chemical
magic might take place. But we don't quite know
what that magic is. So is this warm little
pond idea a viable one? Well, really I have
to say that it's not. Remember this hell on Earth, so this early bombardment
would have meant that warm little ponds
wouldn't really have survived for very long. And so the attention in recent
years have shifted from ponds, to what is sometimes called
the "deep hot biosphere". Now, it comes to a
surprise to people that life on Earth is not just
restricted to its surface. In fact, the substantial
fraction of the Earth's biomass is
actually living inside the Earth, not on the surface. Deep down, nobody quite
knows how low you can go, but it's certainly
some kilometres. And of course the organisms
that live inside the rocks deep down are microbes, and they
live in the pores of the rocks. And this is not a very
congenial place to be. For start, what do
they do for sustenance? Well, basically they have to
make do with what's there. And to be honest, it's
not so much of the rock, though the minerals are
useful for other purposes. But there is stuff coming up
out of the Earth, like hydrogen and hydrogen sulphide
that acts as the fuel for this primitive
metabolism in these microbes. And they're still there. They're still down -- if you
could drill down under our feet for some kilometres, you
would find its teeming with life down below us. And that seems a
safer place to be. If the Earth is being
bombarded, you don't really want to be anywhere near the surface. And some evidence that life
started inside the Earth, not on the surface of the Earth,
comes from these hot springs, the base of the ocean, where
the lava hits the water. Basically, there are regions where the Earth's
plates are moving apart, and stuff is coming
out from deep down. And this hot material
when it meets the water, the water circulates and
reaches temperatures of up to 350 degrees Celsius,
squirting out of those jets. They're often called
"black smokers", because they make black
chimneys on account of the minerals that
they deposit. And what came as a great
surprise to biologist about 35 years ago was the
discovery that this region around these black smokers,
is home to a rich ecosystem, a vast range of microorganisms
making a living at temperatures above the normal
boiling point of water. The water doesn't boil because
of the high pressures there. So making a living
at temperatures above the normal
boiling point of water; and they can support
an entire food chain with invasive species,
like crabs and tubeworms. And now the significant thing
is when you sequence the genomes of the microbes at the
base of this food chain, you find that they're
among the oldest and deepest branches
on the tree of life. You can sort of reconstruct
the tree of life from all the species
and work backwards, and see which organisms have,
as it were, changed least over the billions
of years on Earth. And it turns out to be
these critters that live in these hot spring areas. And also I think -- in my view, the surface around these hot
springs, although it's deep under the ocean, is
still a hazardous place. And it would be more likely
that life would form even deeper than that inside the Earth. But having said all
that, all I told you is that life established
itself on Earth by three-and-a-half
billion years ago. But we don't actually know that
life on Earth started on Earth. It might, for example,
have come from Mars. How could life form on Mars,
and then come to Earth? How is that possible? The next slide says it all. That [laughter] same bombardment
which pulverised the surface of Earth, Mars and all the
other planets in the early days, also served to propel
material around the surfaces. And if Mars takes a hit
even today by a comet, say, ten kilometres across, that will
splash huge amounts of material into [inaudible] orbit. And some of that
material comes to Earth. And it comes as a
surprise to people to learn that there are Mars rocks
right here on Earth. But there are. Here's a picture
of me holding one. Now, I have to say, it's
a bit of a story to this. This picture -- this rock was
collected by Douglas Mawson, unrecognised for what it
is as a piece of Mars. And it was in the
geology department museum at the University of
Adelaide for years and years, until it was recognised as
being of Martian origin. It actually fell in
Egypt some decades ago, and apparently killed a dog. And I think that's the
only known canine fatality from a cosmic object. [Laughter] But in the early
days, they were quite relaxed about this rock and they
used to lend it to me. And I would take it to lectures,
and even travel around the world with it once and would often,
you know -- it was in my pocket, would often forget about it. But it was always a great
topic of conversation in pods. And so, Oh, it's my round, lads. "Oh, look, yes, this
is a piece of Mars." You know, and people
would be sceptical of constellation and so on. But it was always a great
thing to have with me. But now, of course, they realise
it's worth millions of dollars, they don't let it out. [Laughter] But [inaudible] State
University, we have not one, not two, but three Mars rocks. Somebody can ask later on how
do we know they came from Mars. I won't get into that. Anyway, the question of
rocks from Mars was propelled to public fame by none
other than Bill Clinton. This is -- I call this the rock
that made Bill Clinton famous, because he stood on the
White House lawn in 1996 and proclaimed that NASA had
evidence for life on Mars in the form of this Martian
meteorite that was found in Antarctica that contained
these funny little features that for a while looked to be like fossilised Martians,
albeit diminutive. And since then the evidence
has largely gone away. And I think very few
people still feel that this particular
meteorite contains evidence for life on Mars. But, you know, it's an
interesting thought if there was or is life on Mars, we
might detect traces of it in Mars rocks right
here on Earth. So that's an interesting aspect. Okay. So much for the where. Let me move onto the how part. And this is the really
tough part of the problem of life's origin. How did life begin? And I think I can
be quite upfront about this; we haven't a clue. I mean, we really do not know. And it's sort of depressing
to think we may never know. We may never have a
blow-by-blow account of how life on Earth
got started. And part of the reason for
that is it all happened such a long time ago. So even if life on
Earth started on Earth, all traces of the early
processes will have been obliterated a long time ago. However, I think we would
settle for something less than understanding each
step of the process. We will be content to know
simply was it a bizarre fluke, maybe unique in the
observable universe, or is it a chemical
inevitability, that is, is it bound to happen
given enough time? Now, during my career,
it's been very curious, the pendulum has swung
quite decisively. I got interested in searching
for life beyond Earth, and in particular, searching for
intelligent life beyond Earth, aliens -- I'll come
to that in a moment, back when I was a
student in the 1960s. One might as well have
professed an interest in searching for fairies. It was a widely assumed that
among all the scientists that life on Earth was a bizarre
fluke unique to our planet. And no person said it
better than Jacques Monod. He said, "Man at last
knows that he is alone in the unfeeling immensity
of the universe out of which he emerged
only by chance." That was in 1970. Well, I have to say this
did coincide with the period of Gaelic nihilism [phonetic]. And he looks suitably miserable
about his pronouncement. [Laughter] And you might
say, "Well, you know, that was just his philosophy." But Francis Crick, Mr.
DNA, had a similar opinion, and in 1973 wrote, "Life
seems almost a miracle, so and many other conditions
necessary for it to get going." Well, we scientists don't
believe in miracles, so we've got to do
better than that. And so that idea that life is a
sort of a fluke, we are freaks, it's a bizarre aberration
in the universe, that feeling seems
to have changed. And so in more recent years, there have been much
more upbeat comments. So here's one by
Christian Verdu [phonetic], a Nobel prize winning biologist,
just like Francis Crick, drawing a very different
conclusion. He says, "Life is almost bound to arise wherever physical
conditions are similar to those of the Earth." That was in 1995. And he's got this
wonderful phrase that, "Life is a cosmic imperative." And so the question
is, "What is the case? Is life a bizarre fluke, or
is it a cosmic imperative." I get infuriated, because very
often get asked by journalists, "How likely is it that
we would discover life out there beyond Earth?" And I say, "The question
is meaningless." It is meaningless for
a very simple reason, that many of my distinguished
scientific colleagues seem to forget about. Okay? How did life begin? If we don't know the process
that transformed nonlife into life, we can't
possibly estimate the odds of it happening. You cannot put the betting odds on a process that
you don't know. If you know the process, even
if you can guess the process, you can have a stab of
figuring out how likely it is. But as we don't know
what that process was, we absolutely have no clue. We can say nothing whatever
about the likelihood of life starting, which is
the same as the likelihood of life beyond Earth,
absolutely nothing. Now, there's no lack
of real estate on which life may have arisen. And so this is a
satellite, Kepler, now sadly not operating
correctly. It's been up there in space. It's a NASA mission,
and it's been looking for extra solar planets,
that is planets going around other stars. When I was a student, nobody could be sure there
were any planets going around other stars. Now, there's a catalogue
of hundreds, if not, a couple of thousand
of candidate objects. And these objects --
the planets tend to be on the whole much larger than
Earth, but the holy grail is to discover Earthlike planets
going around sun-like stars. And the statistics of this
process are now good enough, though one can have an estimate
of how many Earthlike planets -- depending on a little bit on
how you define "Earthlike", how many Earthlike planets
there are in the galaxy. And this is a typical report
you'll be very familiar with this sort of thing. I'm sure any of you who are
following [inaudible] will have picked up this, in my view,
ludicrously upbeat assessment of the likelihood of
life beyond Earth. There are billions of
Earthlike planets in our galaxy. And the keyword here is
billions, or tens of billions in this case, of
"habitable planets". And people think, "Oh, tens of
billions of planets with life." What they forget is that "habitable" does not
mean "inhabited". They sound the same, but they
are very, very different. Just because a planet
could sustain life of the form we have
here on Earth, doesn't mean it's
going to have it. A habitable planet becomes
an inhabited planet, if and only if, the
probability of nonlife turning into life is quite high;
is not incredibly small. But we don't know that,
because we don't know what the process was. So let me just stress
[inaudible]. If there's any take-home
message from this lecture, is it that we do not know
how nonlife turned into life, so we can't estimate the odds. Now, we can hope, if like
me, interested in the idea of life beyond Earth since being
a teenager, if you feel like me, then you will hope that
there is a fast-track pathway from nonlife to life. You may hope that there's a
life principle in the universe, this law of nature that
says, "Given the matter, given an energy source, given enough time,
then life will out." You may hope there
is such a principle. I hope there's such a principle. But we haven't yet
discovered it. There is no known such principle
in physics or chemistry. We haven't found
a life principle. We could believe that
it is an act of faith, that it might be that;
but we haven't found it. So we must contend to
the fact that it could be that life is restricted to
Earth, maybe it's splashed around a bit in the
solar system. But it could be that
we're unique. And that's -- the
philosophical conclusions of that are very deep. But let's go with the idea,
the nicer idea in my view, that it is much more probable. So I think we're all
agreed that somehow, a chemical mixture
transforms itself into life. So how can we make progress on that mysterious
process that we don't know? Well, the first thing is we
could ask a chemist, of course. Seems like the obvious
thing to do. Could a chemist cook
up life in the lab, and show us how it can be done? Well, the first attempt
to do this was made in a famous experiment
by Stanley Miller, under the guidance of Howard
Urey, way back in 1952. And what they did was
to take the components of what they thought the Earth's
early atmosphere was like, put it in a flask there,
and sparked electricity through it for a week. And a sort of brown sludge
appeared in this flask. And when they analysed
the sludge, they found to their delight,
it contained amino acids. Now, amino acids are the
building blocks of proteins. And so you might think, "Well,
that's one step on the road to life, one small step." And that was the
pervading view in the 1950s. Well, you know, if Miller and
Urey could get amino acids in a week, imagine if
they could get funding to run the process
for a million years. You know, maybe they -- [laughter] it would
just be a road, a pathway down which a chemical
mixture would be inexorably conveyed by the passage of time,
that life is the destination, just more of the same. That early optimism
has gone away, probably because of
thermodynamics it's very easy to make amino acids. In fact, you can find
them in meteorites. You don't need very
special conditions. It's because it's what we call
"thermodynamically downhill". It's favoured, whereas, the
next steps of the process, assembling the amino acids as the peptide chains,
is an uphill process. It goes against the
thermodynamic gradient. And amino acid is only one
part of the whole story. We also need nucleic acids, and
a whole bunch of other things. And really making those
things in the lab it turned out to be really,
really difficult. But part of the problem is,
of course, what we don't want in the origin of life
stories, the only thing like an intelligent designer. And the people who
call themselves "synthetic biologists", or in
the Miller-Urey experiment, they set out trying to design
an experiment, and make life. So even if we could
do it in the lab, even if with enough funding,
we could one day make life, that still wouldn't convince
me that nature would know how to do it without
having a plan in advance without being intelligently
designed, which I don't think it is. So that's one problem. The other problem is
look at this picture. Now, this is a picture
of what is called "intermediary metabolism". These are the pathways
in a modern cell, only a small part of this. And in the tray these things are
known as "reticular grammes", for obvious reasons, [laughter]
almost approaching the complexity of the
London underground map. [Laughter] And so
biology is very complex. And so the question is if you
just account [inaudible] make into building blocks, you know, what about assembling
all those building blocks into something much
more complex like this? So it's a little bit like
saying we've cracked the problem of how the Empire State
Building came to exist. We've discovered
how to make a brick. [Laughter] So the rest must
just be more of the same. So it's not how to make
the building blocks, it's how to assemble them
into these very specific, very elaborate complex
structures. But it's actually a more
fundamental problem running through all of this. It's, really, a philosophical
problem. And it's one that preoccupies me in my own research
in this field. And that is the problem
best asked, "What is life?" And so that's something
that scientists like to do again and again. And it makes great
coffee time conversation, goes on and on and on. But basically, if you talk
to a physicist or a chemist, "What is life", you'll be told
a story in terms of things like matter, and force,
and molecules, and energy, and entropy, and all
that sort of stuff. And a lot of bit's
been worked out. And so that's the
narrative you get. If you go to biology department,
ask a biologist, "What is life," you'll be told a story in
terms of coding, and signals, and instructions, and
translation, and transcription, all those sorts of things. In other words, information
speak. So we have two complementary
descriptions of what life is. One is it's all about
molecules, and shapes, and chemical affinities. And the other is it's all
about information processing. And you might think, "Well,
how can we have chemistry and physics, departments
and biology departments in the same university? These people are talking
conflicting languages." And they say, "No, no, no; these
are complementary descriptions of the same phenomenon." And that's well and good, so long as you're discussing
the phenomenon as we find it. But the problem about
life's origin is that then we're talking
about the physics and chemistry transforming
into the biology. We're talking about matter,
and force, and so on, turning into information
processing. If you like, procrudely, we're
talking about stuff turning into bits, informational bits. How does stuff become bits? How -- because in physics,
the stuff calls the shots. Cause and effect are framed
in terms of particles, and forces, and interactions. In biology, causality
is framed of terms of signals, and information. How did matter dispel
upon information, that type of causal efficacy? It's a very deep problem. There's an analogy, which I
think you will appreciate, and that is we're computing. So here's a screen shot of my
computer a couple of years ago. And this is my beautiful
wife, Pauline, here. And we see we've just been to the Taj Mahal,
all very romantic. And then there are some other
stuff less romantic there. But, you know, to me if I
just had never seen a computer before, Windows would
seem like a miracle. Just remember Crick,
seems almost a miracle. Explain it to me. So if I go to a computer
science department and say, "Explain Windows to me," and
if the scientists took the back of the computer and said,
"Look, I can explain it. We've got some silicon in
here, and there's some copper, and the there's some
ion, and, you know, we noticed with the silicon
if you look very carefully, there's these sorts
of patterns inside. And we're not completely
sure of all the details yet, but we think it's got something
to do with those patterns. And, you know, we're half on
the trail and we will be able to explain all of Windows
very soon in terms of this." Well, you wouldn't
be very impressed, because what you're
getting here is a story about the hardware of Windows. And that's fine; I'm not
denigrating the people who work on computer hardware. Where would we be without them? But in the origin of
life field, the hardware, the chemistry corresponds
to the hardware. It's the stuff of
life, the substrate in which life's magic
is instantiated. What we're really interested
in, what I'm really interested in is the software,
the software of life. So for a hundred years, the origin of life
field has been dominated by chemists looking for the
hardware, and that's fine, they can get on with it. But they haven't made
a lot of progress. In recent years, we've
started asking about, "What about the software? What about the information
processing capabilities? How do we make progress
for that?" Well, maybe you ask
a computer scientist. A famous founder of
Computation, John von Neumann, he and Alan Turing together, responsible for the
modern electronic computer. And von Neumann was very
impressed by the analogy between what is often
called a "Turing Machine", a universal computer, a machine
that could compute anything that was computable
in one machine, a universal general purpose
machine, with the notion of a universal constructor, a
system that could construct, according to a programme,
anything you asked it to construct, including itself. So it would be a
self-replicating machine. And von Neumann wrote papers
and a book about the concept of well asking the question, "Is
it possible to build a machine that could construct
any physical system, including itself?" And so he laid down the
logical architecture of what such a machine would be. And this was before the
unravelling of the genetic code, and DNA, and all that stuff. Turns out that life as we
know it is actually very much like a von Neumann
self-replicating machine. But needless to say,
we haven't made any such machine [inaudible]. Although, some people think the
3D printing is getting rather close to a von Neumann machine. But basically, we don't
fully understand the software principles. We understand a bit
about the hardware, don't understand very
much about the software, but in my personal opinion, advances in understanding
life's origin will come from a better understanding
of the complex wave of information processing
going on inside organisms, and how that may have emerged
from information processing, and primitive chemical networks. So that's where I
think the future lies. But mostly we haven't
gotten there yet. So this is a list of
questions before I go onto the final part of the talk. How did it all start? How did software
emerge from hardware? How did bits come out of stuff? We don't know. How did nontrivial
programmable construction -- because it's not -- so living
organism just doesn't make any old thing, it makes a very,
very specific thing according to instructions contained
in the DNA. How did that type
of programmable and possibly reprogrammable -- because that's how
you get evolution, life gets reprogrammed to
produce something different; how did reprogrammable
construction emerge just from dumb molecules
just banging around and interacting with each other? How did digital information
storage emerge? So we're all convinced
of the power of digital information
processing. And I'm old enough to
remember the side rule. That's what I called
an analogue computer. So side rules you
whipped out of your pocket and did the calculation
like this. These days, we think now
that's really very inefficient. We use digital computation,
and now we have digital radio, digital television,
digital everything. And that's because it's a very, very efficient way
of doing things. Well, life went digital
three-and-a-half billion years ago with life. How did it do that? How did it go from
storing information just in like chemical
gradients, to storing it in these digital units,
like nucleotides, and DNA, and the codons, and so forth? I won't get into it. And then it's all very well to have digital information
processing going on, but it's got to do something. It's got to be useful. If you sequence a molecule
of DNA, it's just a sequence. You can't tell my
looking whether it's junk, or whether it's something
that it's going to code for a biologically
functional protein. There's nothing in
the sequence itself. Nature is blind to
such sequences. It's only in the context
of the entire milieu, and that may have been much more than just the
micro-environmental cell, it could mean the micro
environment of the organism. It's only in that
context we can say that we have biologically
functional or useful information. How did that concept of the global environment
having some sort of -- I would still say causal
efficacy over what's going on in the molecular
level, how did that happen? And let me repeat the
answer, we haven't a clue. I mean, we really
are in the dark. We've got some great ideas. And I have some colleagues doing
great work investigating this stuff, but it's at the
level of toy models. We really feel that
we'd like to understand if there is a life principle,
we think it's in the field of complex designs,
and software, and information processing, that that's where we
would discover it. And we'd like to know if
there is such a principle, is it general across a wide
range of complex systems, or is something specific
about the carbon? Okay. So given that
we're really stuck, how can we test the
hypothesis of lifestyles easily? Is there somewhere we
can just go and find out. There is one way, it turns
out, and that is we look for a second genesis of
life, life two, if you like. If we can find that life
was started more than once, well then -- independently
more than once, well then it does look like
it's pretty easy to happen. Well, what is the most
Earthlike planet that we know where we might go to
look for life two? Would it be Mars? Would it be an extra
solar planet? No. The most Earthlike planet
we know is Earth itself. If it's the case, as Christian
Verdu thinks, that life pops up readily in Earthlike
conditions, it's a cosmic imperative, then surely it should
have happened more than once right here on Earth. Well, how do we know it didn't? How do we know all life
on Earth is the same life? Has anybody taken
the trouble to look? Well, it turns out that
until my colleagues and I raised the awareness
of this issue some years ago, nobody had really
even thought about it. But it could be, I
should say that most life on Earth is microbial life and most microbial life
hasn't been characterised, let alone sequenced,
and cultured in the lab. So most of that life
is mysterious. How do we know it's
all the same life? You've got to delve into
its biochemical innards. You can't tell by looking
whether it's the same life as Earth, or some
other type of life. So it could be that
there is truly alien life under our noses or
even in our noses. [ Laughter ] So if life on Earth started more
than once, we're talking not so much about another branch
from the tree of life, but another entire
tree, two trees of life. How might that have
happened here on Earth? Well, I told you about
the cosmic bombardment. So imagine that the [inaudible],
say, four billion years ago, then along came an impactor,
wham, and blasted a lot of material off,
sterilised the planet, and then things cooled down,
and then life two got going. But then a few million years
later, some of that material with life one cocooned
inside it came back again. Then you'd now have two
forms of life on Earth, life one and life two. And this could have
gone on again and again. So the conclusion is
that we sometimes cause a shadow biosphere. If Earth has, or once
had, a shadowed biosphere, we could conclude it
does start readily. And therefore, it would be
widespread in the universe. We could conclude that life
would be a fundamental, and therefore a significant
cosmological phenomenon, and not just a trivial
low collaboration. We wouldn't then be the freaks
I've been talking about. We would actually feel
at home in the universe. I'm going to finish by just
touching on the subject that I think fascinates
everybody about life in the universe, why we
want to know the answer to this question, and
that is the question, "Are we alone in the universe? Is there anybody out there?" So this is the subject
of setting the search for extraterrestrial
intelligence. And I should just mention in
passing that for some years, I've been the chair of the
SETI post-detection task group. So it's our job to deliberate
on what happens if ET calls. [Laughter] You've ask
[inaudible] question time. But at this age, of course, we
don't know if there's any life out there, let alone
intelligent life. But the way people search for
it is using radio telescopes, like this one at [inaudible] in
New South Wales; very famous. There's even a dedicated
system called the "Allen Telescope Array",
which was partially paid for by Paul Allen, but
has now run out of money. And so it's been
sort of hibernated. The plan is to have
some hundreds of dishes like this dedicated to
just looking to see -- sweeping the skies to see
if there's any radio signal from ET coming our way. But so far, only an eerie
silence and no money. So this is -- the way
forward lies either in getting more money, or we're
thinking a bit outside the box on how we might detect
signatures of intelligent life
beyond Earth. But I'd like to draw this to
a conclusion by a quotation from Frank Drake, who started
the subject of SETI in 1960. So that's 45 years ago. And this was an incredible
gamble when Frank Drake did it. People thought he
was totally crazy. As I've explained, at that time
nobody really believed there was only life beyond Earth. And Frank has been
persistently looking for this. And I have to admire
his staying power. Who else do you know who
has designed an experiment, run it for 45 years,
got a null result, and still remains
upbeat about the future? [Laughter] But Frank is
convinced that we're going to discover intelligent
life beyond Earth very soon. And I hope he's right. But at this stage, we cannot
give the betting odds. But I will finish because
I think he described so well why everyone
cares about the subject of life's origin
and are we alone. They care because it touches
upon what we human beings are, and how we fit into
the universe. So Frank says that SETI is
the search for ourselves, who we are, and where we
fit into the universe. So ladies and gentlemen,
thank you very much. [ Applause ]
This was great. Should have gotten a better score. Also, I really like Ideas at the House- they have tons of lectures.