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Life in Space Roleplaying Exercise: Background Notes 1
Extreme Environment Biologists 4
Cell Biologists 5
Geologists 6
Planet Searchers 7
Anthropologists 8
Evolutionary Biologists 9
NASA Scientists 10


Life in Space Roleplaying Exercise: Background Notes

This exercise will be run in the noon lecture on Monday 3rd September 2001.
These notes are provided to help students who didn't make the lecture.
In this section of the course, we ask the question - is there life
(particularly intelligent life) in space. This is clearly a Big Question -
unfortunately we cannot give you a Big Answer!
When you go out on a dark night, you see over 5000 stars. As far as we
know, every one of them could have planets orbiting it, and all of these
planets could be inhabited by intelligent life forms. So billions of alien
eyes could be looking back at us.
On the other hand, it is quite possible that the Earth is the only
inhabited planet in the universe. There could be nothing else out there at
all.
I'm not going to tell you where the truth lies, between these two extreme
positions. The aim of these six lectures is not to give you any answers,
but to allow you to develop a more refined form of ignorance!
We will use the issue of life in space to address many fascinating
philosophical questions. We will ask - what is life? What is intelligence?
What is the difference between a pseudo science like UFOs and a "real"
science like astrophysics? What is the ultimate fate of Humanity?
The first lecture is an introduction to the issues involved. Rather than me
talking for an hour, I will get the class to play a role-playing exercise.
I get the class to divide themselves up into groups of three.
I then tell the class: "Imagine that you are scientists from around the
world attending a NASA conference on life in space. NASA have invited you
here to discuss what the probabilities are of there being life
(particularly intelligent life) in space. They want to know whether it is
worth them spending billions of dollars on searching for life elsewhere in
the universe. Each group of three of you is an expert in some relevant
field of knowledge. I'd like one member from each group to come down here
and pick up a briefing paper."
I give one of the briefing papers to each group representative (the 9
briefing papers are listed below). I then say "You should read and discuss
your briefing paper in your group. If it baffles you, come and talk to me
about it. Once you've mastered it, you are now experts in some field of
relevant study. However, no one group can crack the problem and estimate
the probability of there being life in space. You will have to talk to all
the other groups. So go around exchanging information! You are not allowed
just to show each other your briefing papers - you have to explain things
to each other, as that way you will learn the material better."
"Your goal is to decide whether you think there is likely to be intelligent
life in space, and whether it is worth NASA searching for it. You will have
to weigh up many pieces of information to come to a sensible conclusion.
Unless you have understood most of the pieces of information in this room,
you will not be able to make an informed decision. You will then have to
weigh up all the different arguments, and come to your own conclusions. At
the end of the lecture, I will ask a few groups to summarise their
conclusions, and answer questions from the rest of the class. If the rest
of the class thinks that you have properly understood the issues, you will
get a prize - some of these chocolates! OK - go!".
Astronomers: Star and Galaxy Counters.
You are astronomers. Using powerful survey telescopes, you map the sky,
counting stars and galaxies. Your whole life is made up of vast numbers -
to you, anything less than a billion is beneath contempt!
If there is life in space, it will need an energy source to keep itself
alive. The best sources of energy seem to be stars - they are powerful,
steady and found in vast numbers. Our local star (the Sun) supplies almost
all the energy to keep life on Earth going, after all. So it seems likely
that life in space will be found near a star (perhaps on a planet or moon
orbiting the star).
So if every star is a potential place for life to exist, how many stars
are out there? Stars appear to be grouped together into clumps called
galaxies. Our Sun lives in the outskirts of such a clump - a galaxy called
the Milky Way. The Milky Way is 30,000 light years across, about 1000 light
years thick, and contains about 1011 stars (1 followed by 11 zeros, ie,
100,000,000,000, or one hundred thousand million stars). That's about as
many stars as there are blades of grass in Canberra.
But there is worse! Our galaxy, the Milky Way, is far from being alone in
the universe. Many many other galaxies can be seen with our telescopes,
each similar to the Milky Way, and each containing about 100,000,000,000
stars. The nearest galaxy to our own in two million light-years away. How
many other galaxies can we see? Well, with the latest observations from the
Hubble Space Telescope, it appears that there are about 1012 galaxies
within range of our current telescopes: ie. 1,000,000,000,000 galaxies (one
thousand billion). The range of our current telescopes is about a billion
light-years. And each of these thousand billion galaxies itself contains
about a hundred thousand million stars, each of which might have life. So
that means there are 1023 stars within range of our current telescopes: ie.
100,000,000,000,000,000,000,000 of them (one hundred thousand billion
billion stars).
And that's not all. This is just the stars within range of our most
powerful current telescopes. We've not seen the edge (if any) - stars just
keep on going as far as we can see, with the same number per unit volume.
So there could be many many more beyond the range of our telescopes. In
fact, some cosmologists believe that the universe is infinite, and hence
that there is a literally endless number of galaxies out there.
So what does this have to do with life and space? Surely, you think, with
so many stars and so much space out there, it would be incredible if life
hadn't started somewhere else in the universe. Even if only one in a
million stars harbors intelligent life, that still means that there are
100,000 intelligent species in just our own galaxy, let alone all the rest!


Extreme Environment Biologists

You are among the world's most daring biologists. Normal biological
researches give way to you as you swagger past. And all because of the
extreme places you work.
Where can life survive? This is the question that fascinates you. Do all
conditions have to be just right for life, or can it survive in hellish
extreme environments?
In one expedition, you took a balloon far up into the stratosphere, where
the temperature was freezing, the atmosphere almost gone, and the radiation
and UV ferocious. Still you found living microorganisms drifting past on
the wind.
In another expedition, you took a submarine several kilometers down into
the depths of the world's oceans, and took samples from the volcanic vents
known as black steamers. Even here, with the temperature far above boiling
point and in the complete absence of light, you found flourishing colonies
of microorganisms (but no Russian submariners).
Next you tried taking samples of rocks from 10km below the Earth's
surface, from a special drilling rig. Once again, you found life, despite
the absence of nutrients, the intense pressure and heat. Coke cans and
McDonalds wrappers were also found (just joking.).
Even in space, you have found microorganisms surviving. Apollo astronauts
retrieved the leg of a robotic spacecraft that had been on the Moon for
years, in a complete vacuum, exposed to temperatures alternating between
-180 and +400(C. Earthly microorganisms were found freeze-dried inside the
leg. Some of them were still viable, and came back to life when returned to
Earth.
Life seems to flourish in volcanoes, in the cores of nuclear reactors, and
almost everywhere else. Life is tough! But what's this got to do with life
in space?
Some people in this meeting will try and tell you that life in space is
unlikely, because conditions for life are so rare. They will say that you
need a planet just like Earth, with a nice temperate climate and lots of
liquid water. You feel that this is (diplomatically speaking) a load of
crap. Even Earthly life can survive in an incredible range of situations.
Life in space may be even more diverse and resilient. Perhaps there are
life forms that flourish in a vacuum? Creatures of plasma that live in the
Sun? Creatures made of superconducting metals that live on Pluto or beyond?
Who are we to put our puny limits on the force of life?
You suspect that life will be found in far more paces than we expect. Go
out and persuade everyone!
For more information, follow this link:
. http://www.astrobiology.com/extreme.html

Cell Biologists

You are a team of cell biologists. You have devoted your careers to
studying the incredible complexity and wonder that is the simplest
biological cell.
What is the simplest life-form that is capable of reproducing by itself?
Viruses and Prions cannot reproduce themselves: they need to subvert a
living cell to survive. So the simplest self sustaining life form is a
single cell - a bacterium or amoeba.
Your research shows that such a single cell is hardly simple. Just look at
the incredible complexity of what has to go on to keep it working! You need
DNA - not a simple molecule. It took tens of thousands of researchers
decades of work to map even one DNA molecule. But DNA isn't enough, you
need an enormous family of transcriptors, RNA etc to enable it to make
copies of itself. Then consider the cell membranes and all the complex
mechanisms for allowing certain things in and out. The mitochondria, the
energy sources - the list goes on and on. Despite decades of work, we are
only scratching the surface of all the processes that take place within
even the simplest cell.
And this is the simplest possible thing that is capable of keeping itself
alive and reproducing. Without these two properties, evolution cannot take
place. Once you have working bacteria, evolution will take over and produce
a great variety of life forms. But where did the first bacterium come from?
Some people claim that you could produce a working, self-reproducing life
form by chance. Perhaps some freak chemical reaction, deep within the
primordial gunk of the Earth, produced some crude chemical that could
assemble copies of itself and start evolving. These people have done
experiments to reproduce possible conditions early in the Earth's history,
and sure enough, organic chemicals such as amino acids are produced.
But that is a hell of a long way from producing a self reproducing
organism. As one you your team said, "Expecting random chemical reactions
to assemble a working cell is a bit like expecting a tornado to blow
through a junkyard and produce a Boeing 747." Only it's worse that that -
even the most complex aircraft is incredibly simple compared to the
simplest cell.
You've calculated that the probability of a random chemical reaction
producing a simple cell, at any time during the life of a particular
planet, is about one in 1040, ie. 0.00000000000000000000000000000000000001.
There may be a lot of planets out there, but these odds are steeper still.
Odds are life will never get started. Even if it does, it will probably
only be in one place -the odds against two planets having this fluke
reaction are pretty tiny. So - you concede that there may be trillions upon
trillions of planets out there. But it seems to you that they are probably
all sterile.
For more information, try the following linkes:
. http://www.sciam.com/explorations/112596explorations.html
. http://www.geocities.com/CapeCanaveral/Lab/2948/orgel.html
. http://www.sigmaxi.org/amsci/articles/95articles/cdeduve.html

Geologists

You are geologists - in fact, you are paleontologists. You search for the
oldest fossils on Earth. Year after year, you drive your landcruisers out
into the most remote parts of the Earth, in outback Australia, far north
Canada or Siberia, searching for signs of life in the world's oldest rocks.
Your skin is weatherbeaten, your hands callused from holding a hammer, and
your eyes have that far-off look of someone used to wide open spaces.
You are interested in the question - how soon did life get going on Earth?
The Earth is known to be 4,600 million years old, give or take a million or
two. Humans only appeared in the last two million years. Dinosaurs appeared
less than 200 million years ago, and the first multicellular organisms
appeared about 600 million years ago. But when did the first single celled
organisms appear?
This is a hard question to answer. Single cell organisms do not fossilize
well. Even if they did, most rocks this old have been through hell -
melted, stretched, eroded and deformed many many times before they fall
under your hammers.
Nonetheless, you have found signs of life in some incredibly old rocks. In
the deserts of WA, you found fossilized stromatolites - mats of
microorganisms that even today live along some coastlines. These
stromatolites were found in rocks over 3,600 million years old! That means
that life was well established when the Earth was only 1,000 million years
old. But there is worse! In Canadian rocks, you found marginal evidence of
life going back over 4,000 million years!
What does this mean for life in Space? It tells you that life got started
on Earth pretty well as soon as it could! 4,000 million years ago, the
Earth had only just solidified, and it was taking a punishing beating from
meteorites. The atmosphere was toxic and radiation intense. Yet there was
already life there!
To you, this suggests that life gets going very easily. The origin of life
cannot be some difficult, implausible process, or it would have taken
longer on Earth. So if it got going rapidly here, despite the difficult
conditions, you suspect that it would get going quickly anywhere.
You are not sure how many planets are out there in the universe. But if
you are correct, most of them should have life.


Planet Searchers

You are astronomers, engaged in the difficult and tedious job of looking
for planets around other stars. Until five years ago, your peers regarded
you as boring, anal retentive nit-pickers. But then you started discovering
new planets, and now they come and ask for your autographs!
There are countless billions of stars out there. But stars are not good
places for life to form - they are seething balls of radioactive gas,
thousands of degrees in temperature with no solid surfaces. If there is
going to be life in space, it will probably need something solid to live on
- a planet, moon or asteroid. Planets are pretty tiny compared to the stars
they orbit, and moons and asteroids are even smaller, but they seem to be
the best environments for life to form and evolve.
So what fraction of stars have planets and/or moons and asteroids orbiting
them? Until recently, nobody had the faintest idea. You cannot just go and
look - a typical star is a billion times brighter than the largest planet,
and it dazzles even the best telescopes. It's a bit like trying to see a
dim light (like a candle) 100 metres away along a dark road. Easy, unless
the person holding the candle is leaning against the bonnet of a car with
its full beam headlights shining at you! We knew that our own star (the
Sun) had nine planets, about 100 moons and over a million asteroids
orbiting it. But is our Sun typical?
You've taken a sneaky approach. As a planet orbits a star, its gravity
pulls the star backwards and forwards very slightly. This wobble is very
small, but with a sensitive technique known as "precision radial velocity
measurement" you can sometimes detect it, if the planet is very large and
very close to the star.
And the results have been spectacular! You and your competitors have
discovered over 50 planets around nearby stars. You find planets around 5%
of all the stars you survey. You have become famous - universities compete
to offer you highly paid jobs, grant money and prizes are showered upon
you, you appear regularly on the TV, and attractive young members of the
opposite sex flock around you in public. Only the astrologers are unhappy,
trying to fit all your new planets into their horoscopes.
Could there be life on these planets? Probably not. Your technique can
only find really massive planets - planets like Jupiter or Saturn. These
planets are probably huge balls of gas with no solid surfaces. They may,
however, have moons, just like our own Jupiter and Saturn. And these moons
might be suitable for life.
Several of your stars have multiple planets orbiting them. Once again, you
can only detect the big planets, but if there are so many big ones, there
might be some small ones too, like the Earth (our Sun has four big planets
and five small planets). And what about the other 95% of stars? They could
all have planets just like the Earth. Though they could also have
absolutely nothing - you cannot tell with current technnology.
So - at least 5% of stars have planets around them. It could be much more
than this - even 100%. That is now certain. What you don't know is if there
are any Earth-like planets out there - planets suitable for life.
For more details, see the notes from ASTR1002:
. http://msowww.anu.edu.au/~pfrancis/astr1002/www6_extrasolar/index.html

Anthropologists

Unlike most of the nerdish scientists in this auditorium, you like to work
with people. You study the human race, and how its cultures and societies
evolve and change. When you are not in the deepest Kalahari investigating
bushman religion, you are lurking undercover in ANU colleges, studying
student mating rituals (dangerous and disgusting work).
Your studies tell you that there is no such thing as a truly stable
society. All societies are constantly changing, constantly reinventing
themselves. This is obvious in a culture like modern Australia. But even
more traditional cultures, such as the aborigines or the Egypt of the
Pyramids, which were once thought to be ancient and unchanging, are now
known to have been constantly varying.
What does anthropology have to do with life in space? Well, what we are
really interested in is intelligent life in space - life we could talk to.
But this may only be a very brief phase in the evolution of any planet.
So - let's imagine that on some distant planet, an intelligent race has
evolved. They might be just like us or unbelievably alien. How long will
they stay around? Surely they won't last long. They may blow themselves to
pieces with atomic weapons, or some other bizarre technological weapons
system of their own. We've only had atomic weapons for 50 years and we've
already come close to wiping out humanity several times. If we keep on in
the same way, sooner or later we'll get unlucky and blow ourselves to
pieces. It may take a few thousand years, but in the cosmic scheme of
things that is only the blink of an eyelid.
The aliens may pollute themselves into extinction. We're already much of
the way there, and we've only had industrial society for about 150 years.
How could we possibly survive a thousand years or a million? And even a
million years is a tiny period compared to how long it took us to evolve
(4,600 million years).
And even if the aliens do not destroy themselves, their society will soon
be so advanced that they may have no interest in talking to us. Just think
how much our society has changed in the last 10,000 years. How much do we
have in common with cavemen? Consider how fast technology is changing at
present. We cannot imagine what the world will be like even ten years in
the future, let alone a thousand or a million. Surely it's enormous
arrogance on our part to think that aliens a million years more advanced
than us would have any interest in communication.
What's all this got to do with finding life in space? Our galaxy is 10,000
million years old, and our Earth is 4,600 million years old, but we've only
been intelligent and technological for a few hundred years. So if any
aliens come here, odds are they arrived 100 million years ago (and had a
really interesting conversation with the dinosaurs), or they will arrive
100 million years in the future (when even our garbage has been erased by
plate tectonics, and we've either died out or evolved into incomprehensibly
philosophical robots). It would take incredible fine tuning to arrive at
the exact instant when we are intelligent and interested in a chat.
So, if we go into space, odds are we will find planets full of bacteria,
or planets on which intelligent life came and went billions of years ago.
We'd have to be incredibly lucky to find someone we can talk with.

Evolutionary Biologists

You are a team of evolutionary biologists. You use a combination of
fieldwork and computer simulation to understand how species evolve and
adjust to their environments. In your spare time you argue with
creationists.
Evolution is an awesomely powerful process. You see it every day in your
lab. In one experiment, you left a petri dish out for a few hours, until it
was covered in colonies of bacteria. You then dosed them with a toxin. 99%
died. You then let the remaining 1% grow and multiply in peace for a few
days. You dose them with some mutation-inducing radiation, and before long
you have a petri dish full of mutants descended from the original 1% of
toxin resistant bugs. You then hit them with a toxin again. This time, only
perhaps 70% die. Once again, you let the survivors recover, and you mutate
them. Over and over you repeat the experiment, and within a few months
you've evolved a new species of toxin resistant bacterium. The same process
happens naturally all the time in hospitals.
All you need for evolution is something that can make copies of itself. It
could be a life-form, or a self-replicating machine (or a self-replicating
computer program, for that matter). The copying process must be slightly
imperfect, and there must be some way to kill off some of the copies. One
you have this situation, evolution is pretty unstoppable. The evolving
thing makes copies of itself. Not all the copies are identical. Some are
better able to avoid being killed than the others. These ones survive, and
make more copies of themselves. And so on.
What does this mean for life in space? All you need is that something
capable of making copies of itself be produced by chance on a planet. Some
people have suggested that this first self copying thing might be as simple
as a strand of RNA, or some bizarre protein. The copying process may be
pretty pathetic at first, and the self copying thing (whatever it is) very
fragile, but soon evolution will work its magic. The copying will get
better and better, the self copying object more and more robust, and before
you know where you are, Bingo! Recognisable life!
How likely is this process? You don't know. Nobody has yet found a
chemical that is both simple enough to form by chance, and capable or
making copies of itself. But many groups consider themselves to be pretty
close.
More problematical for you is the question of intelligence. Once you have
simple evolving life forms on a planet, is it inevitable that they will
eventually evolve intelligence? You are not at all sure about this. On
Earth, life formed about 4,000 million years ago, but it stayed as single
celled organisms until only 600 million years ago. It seemed quite happy to
stay at that level. Even today, single celled organisms are the dominant
lifeforms on Earth.
So if we ever find life in space, maybe it will have got stuck at some
stage in its evolution, or simply taken a bit longer (say 5,000 million
years rather than 4,000 million years) to get to the stage of multicellular
organisms. Or maybe evolution will have gone off in some other direction,
perhaps producing ever more sophisticated bacteria and not bothering with
gluing many cells together. Or maybe evolution got as far as dinosaurs or
kangaroos, and then decided to go no further, or to go in some other
direction (flying kangaroos? Dinosaurs with propellers?). Intelligent life
seems far from inevitable.
To have a go at evolution for yourself, try this WWW link:
. http://alife.fusebox.com/ (and click on the leftmost circle - Morph).


NASA Scientists

You work for NASA (poor sods). When you aren't battling the bureaucracy or
watching spaceprobes crash into Mars, you are studying data on the planets,
looking for suitable environments for life.
The question is this: there may well be very large numbers of planets out
there in the universe. We only have nine orbiting our Sun, but there are a
lot of other stars just like our Sun out there. If most of them have
planets around them, there could be billions of planets in the universe.
But just because there are planets, does not mean there could be life.
Planets could be too cold, too hot, too large or too small. It is hard to
imagine life (for example) evolving on Pluto, where even the air is frozen
and lying on the surface. Or on Venus, with its clouds of sulphuric acid
and temperature of 600 degrees. What fraction of planets are suitable for
life?
Your guess is that life requires a planet with liquid water. That is
pretty restrictive - if a planet is even slightly too close to its star,
all the liquid water will boil off. And if it is too far away from its
star, the water will freeze.
In our solar system, there are three places with liquid water.
. Earth of course - which happens to be in just the right orbit to have
oceans.
. Mars - spacecraft images show clear evidence for floods in the recent
past. You know that Mars has lots of ice - something must be melting
this from time to time - perhaps volcanoes or meteorites.
. Europa - this moon of Jupiter is covered with ice. The ice is cracked
in a way that suggests that an ocean of liquid water lies below it.
This water would be melted by the immense gravitational pull of
Jupiter.
So in our Solar system, two planets and a moon are possible havens for
water based life. That's not bad: 2/9 planets and 1/100 moons. If every
star has a family of planets around it, and about three planets in every
family are suitable for life, that's an awful lot of life-suitable planets
out there.
Bear in mind, however, that this is all based on just one solar system -
our own. Other solar systems could be quite different. And we still don't
know if there is any life on Mars or Europa - it could be that liquid water
isn't enough, by itself, to allow life.