1. Are We Alone in The Universe? - by Sir Martin Rees - August 2004

  2. Are We Alone in The Universe? - by Richard A. Kerr - July 2005

  3. Are We Alone in The Universe? - The Search for An Answer Moves From Telescopes to Computers - by Sean Raymond - January 2005

  4. Are We Alone in The Universe? - In Conversation with Paul Davies and Phillip Adams - November 2002

  5. Are We Alone in The Universe? - by Dr. Sten Odenwald - 1997












Are we Alone In The Universe?
by Sir Martin Rees

Astronomer Royal

10 Aug 2004

from FirstScience Website

More than 400 years ago, Giordano Bruno, an Italian monk, wrote that "In space there are numberless earths circling around other suns, which may bear upon them creatures similar or even superior to those upon our human Earth."


Bruno deserves to be remembered in the millennium year - he was burnt at the stake, in Rome, in the year 1600.

In the late 19th century, the science fiction of Jules Verne and H.G. Wells popularized the idea of alien life. Percival Lowell, a wealthy American, built his own observatory in Flagstaff, Arizona primarily to study Mars.


He believed that its surface was criss-crossed by 'canals', dug by an advanced civilization to channel water from the frozen polar caps to the 'deserts' near the Red Planet's equator.

In 1900, a French foundation offered the Guzman Prize of 100,000 francs for the first contact with an extra-terrestrial species; but prudence led them to exclude Mars - detecting Martians was then thought to be too easy!




Is there life on Mars - the idea has always fascinated us.


How life began, and whether it exists elsewhere remains one of the most fascinating questions in the whole of science - indeed, you don't need to be a scientist to wonder about this.


But we still don't know the answer. We're less optimistic about Mars than our forbears were a hundred years ago. Even if there is life there, it would be nothing more than microscopic 'bugs' of the kind that existed on Earth early in its history - there is certainly nothing on Mars like the 'Martians' of popular fictions.

Indeed, nobody now expects 'advanced life' on any of the planets or moons in our Solar System.


But our Sun is just one star among billions. And in the vastness of space far beyond our own Solar System we can rule out nothing. Astronomers have discovered, just within the last five years, that many stars have their own retinue of planets. There are millions of other Solar Systems.


And there would surely, among this vast number, be many planets resembling our Earth.



Lynette Cook

Life could be everywhere;

over 31 planetary systems

have been discovered around other suns


If intelligent aliens were common, shouldnít they have visited us already?


Some people, of course, claim that aliens have indeed visited us. But the evidence for UFOs is no better than that for ghosts, and I'm personally quite unconvinced.


Some astronomers cite this as evidence that aliens are rare. They note that some stars are billions of years older than our Sun, and point out that, if life were common, its emergence should have had a 'head start' on planets around these ancient stars.

But the fact that we haven't been visited doesn't, in my view, imply that aliens don't exist - the question remains open. It would be far harder to traverse the mind-boggling distances of interstellar space than to send a radio signal. That's perhaps how aliens would reveal themselves first.


The nearest stars are so far away that signals would take many years in transit. For this reason alone it makes sense to 'listen' rather than transmit - if a signal were detected, there would be time to send a measured response, but no scope for quick repartee!


(Aliens equipped with large radio antennae could in any case pick up the combined output of all our TV transmitters - if they could decode them, it's hard to think what they might conclude about 'intelligent' life on Earth!).



Seth Shostak

ET please phone Earth - SETI listens for radio signals from

alien civilizations at the Arecibo Radio Telescope


Attempts to search for such signals have had a hard time getting public funding (even at the level of the tax revenues from a single science fiction movie) because the topic is encumbered by 'flakey' associations with UFOs, and so forth.


But thereís a serious effort in California, backed by hefty donations from some silicon-valley millionaires.

We have no idea what intelligent aliens would look like - it would depend on the habitat that their 'home planet' offered. They could be balloon-like creatures floating in dense atmospheres; they could be the size of insects, on a big planet where gravity pulled strongly. Or they may be freely-floating is space.


They could even, as some science fiction reminds us, be super-intelligent computers, created by a race of alien beings that had already died out.

Even if intelligent aliens existed, they may not be transmitting any signals; and their brains and senses may be so different from ours that we couldn't recognize them. There may be a lot more life out there than we could ever detect - absence of evidence wouldn't be evidence of absence. There are heavy odds against such searches succeeding.

But I'm enthusiastic about these searches, because of the import of any manifestly artificial signal. Even if we couldn't make much sense of it, we'd have learnt that 'intelligence' wasn't unique and had emerged elsewhere.


Our cosmos would seem far more interesting; we would look at a distant star with renewed interest if we knew it was another Sun, shining on a world as intricate and complex as our own.




Galaxies, stars and planets,

a cosmic structure we share with any aliens


If we ever established contact with aliens, what could we discuss with them?


I've argued in a new book that we're assured one common interest. We'd belong to the same universe of stars and planets, all made of similar atoms and governed by universal laws. We'd all trace our origins back to a single 'genesis event' - the so-called 'big bang', which happened about 12 billion years ago.

To firm up the odds on alien life, we need to understand how life begins and evolves. An extraordinary precession of species (almost all now extinct) have swum, crawled and flown during the Earthís 4.5 billion year history.


For a billion years, primitive 'bugs' exhaled oxygen, transforming the young Earth's poisonous atmosphere and clearing the way for our eventual emergence.


We know from fossils that a cornucopia of swimming and creeping things evolved during the Cambrian era 550 million years ago. The next 200 million years saw the greening of the land, offering a habitat for exotic creatures - dragonflies as big as seagulls, millipedes a yard long, giant scorpions and squid-like sea-monsters.


Then came the dinosaurs. Their sudden demise opened the way to mammals - to the evolution of apes and us. We are the outcome of time and chance: if evolution was 're-run', there would be no humans, and we can't predict whether any other species would achieve our dominant role.


So we can't lay firm odds on whether 'intelligence' would emerge on another Earth-like planet.




Is there life under the icy crust of Europa?


We know this happened on Earth, but we'd dearly like to discover a second example where even the earliest stages of life might exist.


Mars remains the best place to look. Three years ago, American scientists announced evidence for fossil 'bugs' on a meteorite that had come from Mars. This claim, hyped up at a press conference attended by President Clinton himself, was dubious and premature - NASA has been backtracking on it ever since.


We'll learn more from a series of space probes that will be sent to Mars in the next decade, to study its surface, and eventually return samples to Earth. And there are longer-term plans to search elsewhere - for instance, a submersible robot will probe the ice-covered oceans of Jupiter's moons Europa and Callisto.

All this depends on the space program.


For most of the present century, space travel was a futuristic concept, familiar from comics and corn flakes packets. But in July 1969, Neil Armstrong's 'one small step' made space travel a reality. Those of us who are now middle-aged can remember viewing 'live' the murky TV pictures of that event: it seemed a high point in a decade blighted by the arms race and the Vietnam war.

Another lasting image from the 1960s was the first photograph of the entire round Earth, taken from the Moon. Our habitat of land, oceans and clouds was revealed as a thin delicate-seeming glaze. Our home planet - the 'third rock from the Sun' - is very special.


The beauty and vulnerability of 'spaceship Earth' contrasts with the stark and sterile moonscape on which the astronauts left their footprints.



Neil Armstrong's giant leap for mankind

was fuelled by the Cold War.


In the 1960s, the first brief excursions to the Moon seemed just a beginning.


We imagined follow-up projects: a permanent 'lunar base', rather like the one at the South Pole; or even huge 'space hotels' orbiting the Earth. Manned expeditions to Mars seemed a natural next step. But none of these has happened. The year 2001 will not resemble Arthur C. Clarke's depiction, any more than 1984 (fortunately) resembled Orwell's.

The program, announced by President Kennedy in 1961, 'to land a man on the Moon before the end of the decade, and return him safely to earth', was lavishly funded because America wanted to beat Russia. Their pride had been badly dented in 1957, when Russia launched the first 'Sputnik', and this was a chance to recapture the lead in the space race.


Reaching the Moon was an end in itself: the last lunar landing was in 1972.

Manned spaceflight now seems a rather jaded spectator-sport: the veteran senator John Glenn's recent trip in the Space Shuttle may have been a morale-booster for elderly Americans, but it didn't recapture the excitement of his pioneering flight 36 years earlier. We admired the Russian cosmonauts more for their fortitude and DIY skills than for anything else, as they coped with one malfunction after another in the decrepit Mir spacecraft.

Nationals of other countries have hitched rides into space. The British astronaut Michael Foal heroically survived the hazards of Mir, the Russian Space Station. French, Bulgarian and Mongolian astronauts have also made the trip.


But none of this has recaptured public enthusiasm.



Perhaps the best astronauts are robots


The practical case for manned spaceflight was never strong, and it gets weaker as robots and computers get more powerful.


Space technology - now funded commercially as well as by governments - has abundantly proved its value. Thousands of small unmanned objects have been launched into orbit.

Satellites are routinely used for long distance telephones and satellite TV broadcasts. The 'global positioning satellites' allow planes or ships to navigate precisely - and allow solo hikers or sailor to locate themselves accurately anywhere on Earth, with a pocket-sized instrument. Weather forecasts depend on pictures and data from space.

Space exploration need not involve humans. It can be better (and far more cheaply) carried out by fleets of unmanned probes, exploiting the advances that have given us mobile phones and high-powered personal computers.

Cameras and scientific instruments have beamed back pictures from the other planets of our Solar system. And the Hubble Space Telescope has imaged stars and galaxies so deep in space that their light set out on its journey towards us billions of years before our Earth and Sun were born.


The cosmos is fantastically larger and more complex than could have been imagined by the ancients who first mapped the constellations.

The cosmos confronted with huge spans of time, as well as stupendous expanses of space. Life on Earth has evolved for billions of years, but our Sun has burnt up less than half its fuel, and will keep shining for another five billion years. If life isn't prematurely snuffed out, our remote progeny will surely - in the aeons that lie ahead - spread far beyond this planet.

We plainly can't forecast the vastly remote future. But what might happen in the first decades of the new millennium? How long will it be before people return to the Moon, and perhaps explore still further afield?



Worth its weight in gold

- a section of the International Space Station


The centerpiece of the current US program is the new International Space Station: this will be in orbit a few hundred miles up, and the size of a football field.


It will be the most expensive artifact ever constructed, costing its own weight in gold. Even if it is finished - something that seems uncertain, given the immense and ever-rising costs, and prolonged delays - it will be neither practical nor inspiring.


Thirty years after men walked on the Moon, a new generation of astronauts will be going round and round the Earth, in more comfort than Mir can offer, but much more expensively. The astronauts will be able to do experiments, but most of those could be done more cheaply by robots in smaller free-flying satellites.

The Space Station would make somewhat more sense as a staging post on the way to other planets. But no such follow-up will materialize unless public enthusiasm revives, or unless some technical breakthrough renders space travel much cheaper and easier than it now seems.

Present launching techniques are as extravagant as air travel would be if the plane had to be rebuilt after every flight. Spaceflight will only be affordable when it adopts the same techniques as supersonic aircraft. Tourist trips into orbit may then become routine. And wealthy adventurers may boldly go further. Future Richard Bransons, for whom round-the-world ballooning seems too tame and routine, could aim for the Moon.


If Bill Gates seeks a challenge that won't make his later life seem an anticlimax, he could sponsor the first expedition to Mars.



Armageddon? - an asteroid impact on Earth



Some people use the so-called 'insurance policy argument' to advocate a manned space program.


There is an ever-present risk (though fortunately a small one) that a comet or asteroid will hit the Earth. The craters on the Moon's surface are records of these impacts. An impact on Earth - leaving a huge undersea crater near Chicxulub in the Gulf of Mexico, probably sealed the fate of the dinosaurs 65 million years ago.

There is about one chance in 10000 that, within the next 50 years, the Earth will be hit by an asteroid large enough to cause world-wide devastation - ocean waves hundreds of feet high, tremendous earthquakes, and changes in global weather. This chance is low - but no lower than the risk (for the average person) of being killed in an air crash. Indeed, it's higher than any other natural hazards that most Europeans or North Americans are exposed to.

The ever-present risk from nature has been augmented since humankind entered the nuclear and biotechnological age. Humanity will remain vulnerable to these (probably increasing) hazards so long as it is confined here on Earth.


But once self-sustaining communities exist away from the Earth - on the Moon, on Mars, or freely floating in space - our species would be invulnerable to any global disaster, and whatever potential it has for the 5-billion-year future could not be snuffed out.

Whether on not humans spread beyond the Earth during the next millennium, we'll still want to know whether we are alone. It would in some ways be disappointing if searches for alien intelligence were doomed to fail. On the other hand, it would boost our 'cosmic' self-esteem. If our tiny Earth were a unique abode of intelligence, we could view it in a less humble cosmic perspective than it would merit if the Galaxy already teemed with complex life.


We'd have even stronger motives to cherish this 'pale blue dot' in the cosmos, and not foreclose life's future - a future that could be even longer than the time span over which simple life has evolved into humans.


That is why we should expand our cosmic vision in the new millennium.







Today, most scientists are convinced that we are not alone. But what life exists in our own back yard Ė our Solar System?

Back to Contents


Are We Alone in the Universe?
by Richard A. Kerr

Science 1 July 2005
Vol. 309. no. 5731, p. 88

from ScienceMagazine Website

Alone, in all that space? Not likely.


Just do the numbers: Several hundred billion stars in our galaxy, hundreds of billions of galaxies in the observable universe, and 150 planets spied already in the immediate neighborhood of the sun.


That should make for plenty of warm, scummy little ponds where life could come together to begin billions of years of evolution toward technology-wielding creatures like ourselves. No, the really big question is when, if ever, we'll have the technological wherewithal to reach out and touch such intelligence. With a bit of luck, it could be in the next 25 years.

Workers in the search for extraterrestrial intelligence (SETI) would have needed more than a little luck in the first 45 years of the modern hunt for like-minded colleagues out there.


Radio astronomer Frank Drake's landmark Project Ozma was certainly a triumph of hope over daunting odds. In 1960, Drake pointed a 26-meter radio telescope dish in Green Bank, West Virginia, at two stars for a few days each. Given the vacuum-tube technology of the time, he could scan across 0.4 megahertz of the microwave spectrum one channel at a time.

Almost 45 years later, the SETI Institute in Mountain View, California, completed its 10-year-long Project Phoenix.


Often using the 350-meter antenna at Arecibo, Puerto Rico, Phoenix researchers searched 710 star systems at 28 million channels simultaneously across an 1800-megahertz range. All in all, the Phoenix search was 100 trillion times more effective than Ozma was.

Besides stunning advances in search power, the first 45 years of modern SETI have also seen a diversification of search strategies. The Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations (SERENDIP) has scanned billions of radio sources in the Milky Way by piggybacking receivers on antennas in use by observational astronomers, including Arecibo.


And other groups are turning modest-sized optical telescopes to searching for nanosecond flashes from alien lasers.



Listening for E.T.

The SETI Institute is deploying an array of antennas

and tying them into a giant "virtual telescope."


Still, nothing has been heard. But then, Phoenix, for example, scanned just one or two nearby sunlike stars out of each 100 million stars out there.


For such sparse sampling to work, advanced, broadcasting civilizations would have to be abundant, or searchers would have to get very lucky.

To find the needle in a galaxy-size haystack, SETI workers are counting on the consistently exponential growth of computing power to continue for another couple of decades. In northern California, the SETI Institute has already begun constructing an array composed of individual 6-meter antennas.


Ever-cheaper computer power will eventually tie 350 such antennas into "virtual telescopes," allowing scientists to search many targets at once.


If Moore's law - that the cost of computation halves every 18 months - holds for another 15 years or so, SETI workers plan to use this antenna array approach to check out not a few thousand but perhaps a few million or even tens of millions of stars for alien signals. If there were just 10,000 advanced civilizations in the galaxy, they could well strike pay dirt before Science turns 150.

The technology may well be available in coming decades, but SETI will also need money.


That's no easy task in a field with as high a "giggle factor" as SETI has. The U.S. Congress forced NASA to wash its hands of SETI in 1993 after some congressmen mocked the whole idea of spending federal money to look for "little green men with misshapen heads," as one of them put it.


Searching for another tippy-top branch of the evolutionary tree still isn't part of the NASA vision. For more than a decade, private funding alone has driven SETI. But the SETI Institute's planned $35 million array is only a prototype of the Square Kilometer Array that would put those tens of millions of stars within reach of SETI workers.


For that, mainstream radio astronomers will have to be onboard - or we'll be feeling alone in the universe a long time indeed.

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Are we alone in the universe?

The Search for an answer moves from telescopes to computers
by Sean Raymond

USA Today (Magazine)


from Encyclopedia Website

"More than 100 planets have been detected around other stars in the last 10 years... None of these are thought to support life because they are [gas giants].... Earth-sized planets have not been discovered [yet because] it is harder to spot smaller planets - much harder."


Sean Raymond is a doctoral candidate in astronomy at the University of Washington, Seattle.



THE SEARCH FOR LIFE outside the Earth is more active than ever as telescopes probe for intelligent life on other planets while robots scour the surface of Mars.


There even are desktop computers that predict which stars might be orbited by Earth-like planets. Moreover, planets similar to Jupiter are being discovered around other stars on a monthly basis.

Imagine a planet orbiting a faraway star. It is a bit larger than Earth and is completely covered by a miles-deep ocean. We think that such "water world" planets exist around some stars. We also surmise that there are others with less water, maybe even much drier than Earth. Can they harbor life? To answer this, we need an understanding of life here on our own planet.


How and when did life originate on Earth? Where did Earth come from? Are there "Earths" orbiting other stars in our galaxy?

Earth formed and resides in the "habitable zone." the distance from a star at which liquid water may exist on the surface of a planet. All life on our globe requires some interaction with water. If a planet is too close to its parent star, like Venus, for example, water will evaporate from its surface; if it is too far, like Mars, then water only can exist as ice.


Like Goldilocks' third bowl of porridge, Earth lies where the temperature is just right. So, the quest for life on planets around other stars begins as a search in the habitable zone.

Astronomy has been an active science for thousands of years, and high-powered telescopes have existed for almost a century. However, planets around other stars only have been detected in the last decade. Why can't we just use our big, fancy telescopes to take pictures of other planets?


Because a planet orbiting another star appears about 1,000,000,000 times fainter than the star! It is washed out completely by the light of the star and impossible to see. It is like trying to hear a whisper from across the stadium during the Super Bowl.

More than 100 planets have been detected around other stars in the last 10 years. However, none of these are thought to support life because they are massive balls of gas hundreds of times as large as Earth with no surface to stand on! The reason that Earth-sized planets have not been discovered is that it is harder to spot smaller planets--much harder. The method used relies on the wobble of a star as a planet goes around it.

For example, picture a seesaw with a football player on one end and a kitten on the other: to balance the seesaw, the fulcrum needs to be placed very close to the football player. The kitten travels way up and down, but the muscular athlete moves very little. The idea is the same for a planet orbiting a star. Like the kitten, the planet is much less massive than the star, and it moves very far compared with the star.


Yet, like the football player, the star does move, albeit in a much smaller orbit. The star's wobbling can be detected with extremely sensitive instruments, and the presence of the planet can be deduced - remember, we merely can see the light of the star, not the planet.


It is easier to locate more massive planets since the star's wobble is greater, just like the football player's motion is greater if he is balanced by a 10-year-old boy instead of a kitten.


The wobble of a star due to the orbit of a terrestrial planet is so small that, employing this method, finding such a planet is nigh impossible.

New techniques, however, always are on the horizon, and a pair of upcoming space missions hope to detect a terrestrial planet around another star: the Europeans are launching Corot in 2006 and NASA is unleashing Kepler in 2007.


The hope is to uncover planets as small as a few times the mass of Earth. In addition, the European Space Agency's Darwin and NASA's Terrestrial Planet Finder missions are scheduled to launch in the next 10-15 years--with the hope of finding a few dozen terrestrial planets and probing the composition of their atmospheres to search for signs of life.

If these missions fail to uncover any signs of life, does that necessarily mean that Earth is unique, containing the only life in our galaxy? Absolutely not. These missions merely will be able to search for planets and life around roughly 50 stars, a tiny subset of the 100 billion existing in our galaxy. It is like picking one strand from an enormous haystack, hoping to find the needle.


In this case, though, we do not know how many needles are in the haystack: the range is anywhere from zero to millions. It will take decades, maybe centuries, before we have a clear picture of what the terrestrial planets in our galaxy look like, and whether there is life on one or more of them.

Some scientists have approached this dilemma via an alternate route. Since the formation of the planets in our solar system is relatively well understood, we can simulate this process in a variety of conditions in which planets could form around other stars. We can analyze the bodies that form in these computer simulations to see how numerous Earth-like planets are, and how often they take shape in the habitable zone.


In addition, we can attempt to predict whether habitable terrestrial planets can be created around a star based on characteristics that can be observed with a telescope. These predictions can help missions like Terrestrial Planet Finder to choose their lists of target stars in order to increase the likelihood of finding potentially habitable planets.

What really makes a planet able to support life?


A planet can form in the habitable zone and have the necessary temperature for water to be liquid on its surface, but contain very little or no water. Having an orbit in the habitable zone is not enough: water is needed to support life. To better understand this phenomenon, let us look at how Earth formed and acquired its water.

Earth once was a large disk of dust and gas, slowly accumulating smaller bodies over a 50,000,000-year span. Each body that impacted Earth had a slightly different composition, because it formed at a different distance from the sun at a different temperature. The boundary separating dry and icy material falls at about 2.5 times the Earth-sun distance in our solar system, between the orbits of Mars and Jupiter, and is called the snow line.


Everything formed inside the snow line was completely dry, but past it are a mixture of rocks and ice. Since Earth has a lot of water, it must have been hit by a large number of objects that formed past the snow line and delivered water to the otherwise dry planet.


Earth mostly is made up of building blocks that formed in the habitable zone or nearby, but all of its water came from material forming past the snow line.

Once we understand how Earth acquired its water and became a habitable planet, we can apply this knowledge to computer models and test how terrestrial planets form in other environments to see whether our solar system is the exception or the role.


What these experiments demonstrate is that the terrestrial planets in our solar system - Mercury, Venus, Earth, and Mars - are part of a continuum that can appear in various shapes and sizes.


These simulations of possible planet systems indicate that every conceivable combination is out there and probably some we cannot imagine. Some planets in a star's habitable zone will be dry, but most will contain at least some water while others may be water-rich. In one simulation, a planet 3.8 times the mass of the Earth with 40 times as much water was the only terrestrial planet to form around its star, on an orbit very similar to that of the Earth around the sun.


The surface of such a planet would be covered with a global ocean many miles deep with no land in sight.


The chance that life could exist in such a place is not well understood because this type of environment is completely foreign to our solar system, but the possible existence of these "water worlds" is very exciting, and could provide ideas for budding science fiction writers.

Planets form in the habitable zone under a variety of conditions.


If the creation of planets like the Earth can happen in so many different environments, then it is likely that Earth-like planets will prove to be relatively common in the galaxy, although it probably will be a long time before observations can confirm or reject this.

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Are We Alone in the Universe?
In Conversation with Paul Davies and Phillip Adams


from MoreBigQuestions Website


Phillip: Human language is daunted by the scale of the cosmic enterprise. Words fail us when we gaze up at the stars and try to contemplate their significance - and our insignificance.


But there is a word that Iím fond of, one that attempts to describe the feelings of awe, wonderment, curiosity and dread that fills us when we look up into the skies on a clear night. The word is Ďnuminousí. And with the feeling of the numinous comes another big question.


Are we alone? Are there other forms of life - particularly of conscious life - out there? Should we attempt to make contact? How might this be possible? On the one hand, we acknowledge that the right conditions to kindle life might be so rare, so fugitive, that weíre doomed to cosmic solitude. On the other hand, weíre dealing with such immense numbers of suns and, presumably, of planets, that life forms may be as bountiful in the cosmos as they are on Earth.


After all, in the observable universe there are 1020 - 100 billion billion - suns.

Paul: Thatís a lot, isnít it, a big number. Unfortunately not so big that if life formed as a result of an accidental shuffling of molecules - that is, if life is a chemical fluke - then it would be bound to occur twice.

Phillip: But what if you add to those 100 billion billion suns the number of possible planets? You are then dealing with an even greater number.

Paul: Itís just another factor of ten or so. People are very bad at large number estimates. They think that a million is awfully big, and a billion just a bit bigger, and so on. Although 100 billion billion sounds like an enormous number, it is still absolutely tiny compared to the odds against forming life by random shuffling. It is undeniably true that the universe is vast: there are a huge number of stars and probably planets too.


Nevertheless the odds against shuffling, say, amino acids into proteins, which we were talking about previously, are enormous - like one followed by 130 zeros as opposed to your puny number here of one followed by twenty zeros! A hundred billion billion doesnít begin to scratch the surface of the improbability of forming life, if it formed purely by accident.


So if life is merely a chemical fluke, we are alone. The only possibility of us not being alone is if there is something other than just a random shuffling process involved.


E.T. Phone Greece

Phillip: There are conflicting human emotions at work here. On the one hand, it is a very bleak thought, to suppose that we are alone in the universe. Many of us would like the company of user-friendly species from other galaxies. On the other hand, we have always been very arrogant; we rather like to think that we are at the centre of things.

Paul: In some cultures, yes. But not all. The same argument was raging even in ancient Greece over 2000 years ago. The Greek atomists believed that we are not unique. They reasoned that the universe is nothing but indestructible particles moving in the void.


This led them to conclude that extraterrestrial beings exist because if atoms can come together in certain combinations to form living things here on Earth, then they might do so on other worlds, too.

Phillip: Does Christianity generally accept the notion that we are alone?

Paul: Christians have traditionally hated the idea that there could be intelligent life elsewhere. It causes all sorts of doctrinal difficulties for them. The problem is not so severe in other religions, but Christianity has particular difficulty, I think, with life elsewhere in the universe because Jesus Christ is traditionally held to be the Savior of mankind only, which is hard on any alien beings whose ethical or spiritual stature might dwarf that of humans.


Don't Forget The Sunscreen

Phillip: Letís reduce the scale from our 100 billion billion suns. Letís look at our own sun and one of our neighboring planets - Mars. There has been a lot of speculation about life on Mars recently.

Paul: Yes, there has. Mars has always been at the forefront of speculation about life beyond Earth. Remember how 100 years ago Percival Lowell claimed he saw canals on the surface of Mars? He believed there were alien beings who built these structures to bring melt water from the poles to the parched equatorial regions of the planet.


Then in the 1960s our spacecraft went to Mars and didnít find any canals, or any other signs of life. For a while it looked as if Mars was not only red, but dead too.

Phillip: Of course, there are the pseudo-scientists who claim there is a giant face on Mars surrounded by pyramids.

Paul: Yes, there is the famous Ďface on Marsí too, but weíre not taking that seriously! The two Viking spacecraft that NASA sent to Mars in the 1970s were specifically designed to search for life. They scooped up some topsoil, analyzed it in little on-board laboratories, and didnít find any compelling evidence for life - even microbial life.


In fact, the surface of Mars turned out to be a pretty dreadful place. Itís exceedingly dry, and very cold - rarely above the melting point of water. On top of that, it is drenched in deadly ultraviolet radiation, and the soil is incredibly oxidizing, which is very dangerous to life. All in all, the surface of Mars is extremely hostile to any form of life that we know.

Phillip: But Paul, you have established that life occurred on Earth in extremely inhospitable circumstances.

Paul: That is true, and there has been some speculation that Antarctica can reproduce conditions not very dissimilar to the surface of Mars. Remarkably, there are organisms that live in the dry valleys of Antarctica that I think could live on the surface of Mars even today, if only they could be shielded from the ultraviolet radiation.


So, I agree, it is not obvious that the surface of Mars is completely hostile to life even today. But nevertheless, itís not a place you would want to be stranded - Ďnot the kind of place to raise a kidí, as Elton John sang in ĎRocket Maní.


I think the real reason why Mars looks promising from the point of view of life is that we know that in the past it was warm and wet. The photographs of the Martian terrain show unmistakable signs of river valleys, and there were times when there was so much water on the surface of Mars there may even have been an ocean.


Going back about 3.8 billion years, to a time when we know that there was probably life here on Earth, Mars wasnít so very dissimilar from Earth. So, I think that although Mars doesnít look terribly friendly for life today, in the past it would have been a different story.


The Hitchhiker's Guide For Organisms

Phillip: Let me return to the matter of the bombardment where the Earth, our planet, was patinated by large amounts of rubble being attracted to it. One possibility is that life might have been introduced to Earth as part of that process.


Given that rocks have been traded back and forth between the two planets, could perhaps Earth life have been transmitted to Mars?

Paul: In my mind there is no doubt that if material can travel between the two planets, then so can organisms. It is entirely possible that microbes can hitch a ride on a rock and make their way from Mars to Earth or visa versa.


We know that Mars and Earth receive hits from time to time with enough force to splash material into space; at the moment this happens about every few million years or so, on average.


The ejected debris will be scattered around the solar system, and some of it will inevitably be swept up by other planets.

Phillip: So, Paul, all things considered, do you think that there was life on Mars?

Paul: Iím absolutely convinced that there was, in the remote past, if for no other reason than it would have got there from Earth along with the displaced rocks. The bombardment that took place in the early history of the solar system was so intense that it would have propelled an enormous number of rocks backwards and forwards between the two planets.


We know that Mars was warm and wet at the time there was life on Earth, so I think it was inevitable that some Earth microbes would have made their way to Mars inside ejected rocks and found conditions there rather congenial.

Phillip: But would these little microbes piggybacking on pieces of rock have made it alive across that distance?

Paul: I agree it does seem extraordinary that even a microbe could travel through inter-planetary space without being killed, but when you look at it carefully, it does appear to be possible. The first hazard is getting blasted off a planet by a major asteroid or comet impact event. While this looks unlikely, it actually turns out that an appreciable fraction of rocks can be flung into space by an impact without being unduly shocked or compressed.


The Martian meteorites that we have here on Earth, for example, havenít been pulverized.


I think a microbe could survive ejection from a planet. It could also survive the radiation in space because, cocooned inside the rock, it would be shielded from the worst of the ultraviolet radiation from the sun, and from the worst of the cosmic rays too. On arrival, a rock with a suitable trajectory could be braked by air friction and hit the ground at low speed without burning up.


So, yes, I think a fraction of microbes could make it unscathed from one planet to another.


Meteorite From Mars Kills Dog

Phillip: Conversely could life have begun on Mars and then been transferred here?

Paul: Absolutely. In fact, I think there is some reason to favor Mars over Earth for the origin of life. Mars is a smaller planet, so it would have had less of a bombardment problem. It would have been possible for microbes to live deeper in the Martian crust because it wasnít such a hot planet.


Also, it is easier to blast stuff off Mars because of its lower gravity. So there is a chance that life began on Mars, maybe as early as 4, even 4.2, billion years ago, and was subsequently conveyed to Earth in some of the debris that was splashed off at a later stage. If that is correct, it leads to the bizarre conclusion that we are all descended from Martians!

Phillip: How can we be sure that a rock on Earth had a Martian origin?

Paul: Well, as it happens, the University of Adelaide has been in possession of a piece of Martian rock for decades, although nobody realized it until Dr Vic Gostin spotted its significance a few years ago. It is part of an object that fell in Egypt in 1911 near the town of Nakhla. Incidentally, it killed a dog.


This is the only known example of a canine fatality caused by a cosmic object! To look at, this Martian meteorite is unremarkable. Frankly, itís little different from any old bit of rock that you might find in your garden.

Phillip: We established earlier that physicists, mathematicians and other members of your profession are regarded as high priests. I confessed to having a blind faith in your utterances, but I want you to convince me that there is rock on Earth that has come from Mars!

Paul: You canít tell by looking at a rock that it has come from Mars - it is not red or anything. The first clue is that it is a type of rock called igneous, which means that it was produced by volcanic activity. Meteorites of the common-or-garden variety are all bits of debris left over from the formation of the solar system - primordial and largely unprocessed rocks that were not accumulated into planets. If something is made by a volcano, then there is only one place it can have originated, and that is a planet.


So this rock must have come from a planet. Did it come from the Earth? Earth has volcanoes. No. How can we be sure? Because we have got a pretty good understanding of what Earth rocks are like. When you study the chemistry of this rock, you find that it is subtly different from any rocks on Earth. In particular, the oxygen isotopes in rocks from Mars have different ratios from Earth rocks and, incidentally, from moon rocks.

Phillip: So it has a Martian fingerprint all over it.

Paul: At least a non-terrestrial fingerprint. So, we are looking for a planet in the solar system, other than Earth or its moon, with volcanoes.


Mars is the obvious answer. Look at the pictures of Mars - it has some of the biggest volcanoes in the solar system. Itís a volcanic planet. However, even that is not the clincher. It turns out that the best evidence we have that meteorites come from Mars - and there are about a dozen of them that have been collected so far - is that trapped within the rock are gases from the Martian atmosphere.


In the 1970s the Viking spacecraft, which landed on the surface of Mars, measured the different isotopes of the gases - argon, xenon and so on - in the thin Martian air.


Those isotope ratios match exactly the isotope contents of our Martian rocks. That is just too much to be a coincidence, so they clearly do come from Mars. I donít think many scientists now seriously doubt that.


The Secret Life of ALH84001

Phillip: Do any of our Earth-bound meteorites contain hints of life?

Paul: Yes, a meteorite found in Antarctica in 1984, code-named ALH84001, contains tantalizing evidence for life. Indeed, there are some scientists at NASA who are convinced that life has been at work in that meteorite. There are three reasons why the NASA scientists are excited by it. One is that it contains tiny grains of carbonate - and to a geologist carbonate suggests one thing: water.


Of course, all life as we know it depends on water. If you look very carefully with a microscope at these carbonate grains, there are other features, little mineral inclusions within them, which suggest that some sort of organic processing has gone on. If you saw such features in an Earth rock you would attribute them to bacterial activity.

Phillip: It wouldnít be a line call? You would be absolutely confident that it was bacterial activity?

Paul: It would be pretty certain if it was in an Earth rock, yes. But of course if you see it in a Mars rock, you think again. However, the mineral grains were not all.


The scientists from NASA also found ring-shaped organic molecules known as PAHs which living organisms can produce. Unfortunately PAHs can also be made by normal chemical means, so it is not conclusive evidence for life.


The third line of evidence, and I suppose the thing which most captured the public attention when the results were announced, was the existence of tiny little sausage-shaped features, little microscopic blobs, reminiscent of fossilized bacteria. Nobodyís claiming they are living bacteria, but they could be bacterial fossils. All these findings have been disputed - the jury is still out on them.

Phillip: How old would these putative fossils be?

Paul: The figureís a bit rubbery, but 3.6 billion years seems a good estimate. These could be very ancient Martian microbes.

Phillip: And what prospects are there for life on Mars today?

Paul: As we discussed earlier, the surface of Mars is not very promising for life. However, deep underground, where the permafrost is melted by geothermal heat, conditions may well resemble those beneath the surface of the Earth, a region we know is seething with microbial life. My personal belief is that there probably is microscopic life in the subsurface zone on Mars even today.

Phillip: Okay, letís take the optimistic view that yes, life did exist on Mars, and may even exist on Mars today. If that is the case we can extrapolate to the wider universe. The probability is that many of the billions of stars we have mentioned have planets. Do you take the view therefore, that life is likely to be bubbling away all over the cosmos?

Paul: Because we are almost completely ignorant of how life began, that is an open question. Personally I would say that life is common throughout the universe, but I am arriving at that point of view largely on philosophical rather than scientific grounds.

Phillip: Philosophical? In what sense?

Paul: I donít believe that we are freaks, that life on Earth is the result of a single stupendous, meaningless accident. I think that life is part of the natural outworking of the underlying laws of physics, laws that govern a bio-friendly universe.


Emotional Intelligence

Phillip: Is that an emotional need of yours?

Paul: Probably, yes. Iím coming at this entirely from the philosophical, or, if you like, emotional direction. Not from a scientific direction, because the scientific evidence is very equivocal. We donít know how life began. We have no idea whether it was a unique event or whether it is something that occurs easily under the right conditions.


I might say that many scientists are biological determinists: they think that it is rather easy for life to form under the right conditions.


They also point out the fact that the basic building blocks of life, the amino acids and so on, are very common throughout the universe, and that the stuff of which life is made - the basic elements like carbon, nitrogen, oxygen, hydrogen and so on - are among the most abundant elements in the universe.


Therefore they conclude that life is likely to be abundant in the universe, but we donít know that. It is pure conjecture.

Phillip: If there is a miracle - and as an atheist I find that an embarrassing word to use - but if there is a miracle in the story of life, I find it in the growth or the development of consciousness: self-regarding, self-aware consciousness. Is there in your view a likelihood that consciousness would develop in other realms on other planets? Is that a part of the inevitability, the coding?

Paul: If we accept Darwinís theory of evolution as a complete picture of the evolutionary changes that have taken place among life on Earth, then it would seem extremely unlikely that consciousness would develop anywhere else.


Consciousness would simply be a quirky little by-product of the blind groping of evolution, in the same way that fingernails and eyebrows and so on have appeared. In other words, they donít have any deep significance.

Phillip: Some quirk.

Paul: Naturally we regard it as immensely significant because we are the products of it. However, there is no known law that operates in evolution to direct the evolutionary change towards consciousness or intelligence. If evolution is blind, if it is just a random groping through the space of possibilities, then the chances of Earthís evolutionary pathway being paralleled on another planet are infinitesimal.


Of course, if there is more to it than Ďblind watchmakerí Darwinism, then this conclusion may be wrong. Consciousness and intelligence may emerge as a natural by-product of bio-friendly laws. We donít know, but it is important to put the matter to the test.

Phillip: By test, you mean SETI - the search for extraterrestrial intelligence - using radio telescopes to seek out signals from alien civilizations? Given your optimistic philosophy, do you regard SETI as a worthwhile project?

Paul: When people ask me about SETI I say that it is almost certainly a hopeless enterprise, just because of the enormous odds against locating an alien intelligence even if the universe is full of them. Still, itís a glorious enterprise nonetheless, and well worth doing. I am a thorough supporter of SETI. Alas, though, the chances of success are extremely small.

Phillip: Letís entertain a hypothesis, a mind game: Life abounds in the universe. Conscious life, despite its improbability, evolves. Alien beings decide to go on shopping trips, explorations, and visit Earth.


Of course, such visits are passionately believed in by many, many people, most of whom live in California! What in your view is the likelihood of successful space travel.

Paul: Suppose we do live in a universe in which not only life is inevitable, but conscious, intelligent life, too. Suppose furthermore that some fraction of intelligent life develops into technological communities.


You might then conclude that the Earth should have been visited, and might still be visited today, by alien creatures. It is an argument, incidentally, often used in support of the contrary belief, that life is unique to Earth - the Ďwhere-are-they?í argument. If the universe was teeming with life we ought to see evidence of these alien beings, and as we donít, therefore we must be alone.


My feeling about this is that if life does develop to the point of technology, it makes no sense at all to travel in the flesh from one star system to another. It is immensely expensive. It is one thing to travel from planet to planet within a given star system - we will be able to do that soon - but traveling between star systems is quite another thing.


The distances are so immense: the nearest star is 4 1/3 light years away from Earth.

Phillip: Turn it into kilometers or miles.

Paul: A light year is about ten trillion kilometers or six trillion miles. To put that into comparison, light takes a second or so to reach Earth from the moon, and about 8 1/2 minutes to reach us from the sun, which is a 150 million kilometers away.


Weíre talking 4 1/3 years to the nearest star. Now if the universe is teeming with life, as some people suggest, and if there are many, many technological communities out there, physical space travel would be a poor way to make contact.


It would make much more sense for an alien civilization to log onto the nearest node of the galactic internet and upload the video of their planet to their friendly alien neighbors next door, than to literally travel there in the flesh. The cost of interstellar travel is so horrendous that it makes no ecological or economic sense to do it.


If thereís an intelligent community out there that can communicate, we could contact them much, much less expensively by radio or laser once we know where they are located.

Phillip: Then, of course, there is the problem of the timing. Our planet has existed for four billion years, while something approaching the human being has been around for a mere four million years.


And that human being has been capable of sending radio signals for only about four decades. So you would need some amazing synchronicities to be occurring.

Paul: Thatís absolutely right. A lot of people have an image of alien beings that are only a few decades ahead of us technologically.


They donít realize how improbable this is. As you point out, life on Earth has taken about four billion years to evolve to the point of technological society. Now supposing, hypothetically, there was another planet out there where life got going at exactly the same time as it did here on Earth.


There have been so many accidents of evolution, so many little byways in the evolutionary process, that the chances of the same sequence happening on another planet, reaching the same point of development to within 100 years or so of us is infinitesimal.


That is why I donít believe the UFO stories because the reported aliens are just too much like us, not only in bodily form, but in their level of technology. If you read the reports, UFOs seem to be something like the next generation of stealth bombers! Just 100 or 200 years ahead of us technologically.


The chances that any two planets would arrive at that similar level of technology after four billion years of evolution are simply infinitesimal. Then take into account the fact that there have been stars around for billions of years before our solar system even formed. There could be planets - and indeed life forms - that stretch back for many more billions of years than life on Earth.


The conclusion you arrive at is if there are other intelligent beings out there, they will either be way, way ahead of us technologically, or way, way behind. If the latter is the case, they wonít be signaling us across interstellar space. So if we do succeed at SETI and pick up an alien signal, it is likely to be from a civilization enormously more advanced than ours.

Phillip: Previously, I quoted Asimov's term Ďthe armies of the nightí, which he used to describe the serried ranks of those opposed to science. You might also argue that the term could be applied to believers in the UFO phenomenon, although in this case the armies of the night are people with a passionate love of science.


They love science to such excess it would seem that they have turned the UFO into a sort of twentieth-century religion. There is a paradox here.

Paul: I think that the UFO scene really is religion with a thin veneer of science. What is happening is that old fairy stories or Bible stories of religious visitation have been overlaid with technological language. I was always impressed by Ezekielís vision of four flying wheels, full of eyes, out of which stepped an angel with the likeness of a man.


Replace Ďwheelí by disc, Ďeyesí by portholes, and Ďangelí by Ufonaut, and you have a classic flying saucer story!


Virtual Reality

Phillip: Americaís energetic pop culture has given us a series of fads. Thereís been the yo-yo, the frisbee, the hula hoop and the flying saucer - all things, I point out, that spin.


Now the latest phenomenon is, of course, the bodily abduction, as big a fad as the yo-yo. I was recently alarmed when I met and talked with a professor from Harvard whoís a passionate believer in bodily abductions, having interviewed, he says, simply hundreds of abductees. Your view on this please.

Paul: I have my own theory about alien abductions. It may not explain all of the cases, but I think it explains some. The abduction stories have many features in common with a phenomenon known as lucid dreaming. Iím not talking about vivid dreams; we all have vivid dreams. Thereís another type of dream state, quite different, which most people will have spontaneously perhaps only once or twice in their lifetime. I have certainly had lucid dreams.


How do they differ from ordinary ones? In a normal dream everything has a sort of wishy-washy quality.


By contrast, in a lucid dream things take on a type of reality which is every bit as sharp and real as you and me sitting here now. If you are not aware that you are having a lucid dream - these days I always am, but if you didnít know it - it could be quite terrifying. A well-known feature of the normal dream state is a sense of paralysis.


Weíve all had that dream where we are trying unsuccessfully to run away from things. If you get that feeling in a lucid dream it can be really very scary - I have had the experience myself.


Another prominent dream image is levitation, a sense of floating or flying. Again, it can occur in the lucid dream state, too. There can also be a strong sense of a malevolent presence.


When I have a lucid dream, I usually think that somebody has broken into the house, and they are in the room, standing at the end of the bed.

Phillip: So you are suggesting that these dreams can be conflated with reality?

Paul: Well, you see, if you put all those elements together you have many of the aspects of alien abduction. Somebody falls asleep, in the middle of the night they have a sense of a malevolent presence nearby, they are paralyzed, and find themselves floating.


The other distinctive feature of lucid dreams is that you have a strong sense of touch. Again, in the lucid dreams Iíve had, it is usually a feeling of something prodding or poking me.


When I was a child and would have these dreams, I thought the cat was walking over me.


The Intergalactic Shortcut

Phillip: Okay, I can accept that, particularly if the dreams are then to some extent choreographed by a mass media or given a form and structure. Now I would be remiss if I didnít ask you a final question, and that is the wormhole argument.


The late astronomer Carl Sagan suggested that it may be possible for interplanetary, intergalactic, cosmic visitations to occur through the wormhole. Your response?

Paul: It is quite interesting, historically, what happened here. Carl Sagan wrote the book Contact, now a movie starring Jodie Foster. It features a so-called wormhole as an imaginary mode of faster-than-light space travel.


When Sagan finished the book he went to his friend Kip Thorne at Caltech to discover if rapid transit through a wormhole could really be done.


So there began a sort of recreational mathematical exercise to see if it was possible to have a shortcut between two points in space that would enable rapid transportation from one place to the other. It is already known that black holes can do funny things to space and time, and Saganís hypothetical wormhole is somewhat like an adaptation of a black hole.


As a result of these theoretical studies, Thorne and his colleagues decided that it was just about feasible - not a very practical proposition - but just about feasible that you could have such a wormhole.


But there was a bizarre twist to this conclusion. It turned out that if you could go through the wormhole and come out the other end a short time later, maybe only a few minutes later, then the wormhole could also be used as a time machine, it could send you back in time!


So most of the theoretical work that has since been done involves looking at mathematical models of wormholes in the context of time travel rather than space travel.


However, it does look like it is theoretically possible to create a wormhole and use it for space travel, but it would certainly be a very expensive exercise.

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Are we alone in the universe?

by Dr. Sten Odenwald


from AstronomyCafe Website

We have no hard evidence at this time that there is life to be found anywhere else in either our solar system, or the rest of the universe.


Still, as an astronomer, I think the chances are very good that life exists elsewhere.

Paleobiologists report that life on this planet may have arisen not once but several times when the Earth was very young, perhaps only a few hundred million years old. During this period, there were many frequent impacts with very large asteroids as the formation of the Earth was ending or the Moon was being formed, and each of these impacts would have incinerated any biological system then in existence.

The planet Mars very likely had lots of running water on its surface when it was very young, but lost it all once the atmosphere leaked away. But there could have been a period lasting over one billion years when bacteria like that on Earth could have formed. That's why we are now excited about looking for fossils of ancient martian bacteria on Mars.


If we find them, that will mean that the conditions for evolving life, even just bacteria to start with, are fairly generous and we could expect lots of bacterial life in the universe given that a planet orbits its star at the right range of distances.

We now know that our solar system was formed in a way that is common to many stars. We have observed disks of matter orbiting young stars, and even old ones, that is probably dust and asteroidal material. We have even detected signs of planets orbiting several stars, though additional work is needed to firm up this as the only explanation for the data we have.

So, I think the chances are better than ever that there is life elsewhere in the universe.


We still don't know how often evolution ends up with intelligent beings. This may be very rare considering the fickle conditions that had to occur on Earth for mammals and intelligence to become an important evolutionary skill.


Dumb animals lasted billions of years on this planet before something like homo sapiens evolved!


A universe filled with bacteria and dinosaurs could be the rule, not the exception.


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