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Life in the Universe and Aliens

How did it all start? How did this Earth we proudly call our own really begin? How did life begin?

These are timeless questions that have been asked by our ancestors from time immemorial. When humans turned from being hunter gatherers to farmers they suddenly had more leisure to contemplate the Universe and they began to ask such questions.

The awesome spectacle of the Milky Way on a clear moonless night must have had a profound impact on moulding our collective psyches over generations. Many religions and philosophies evolved with the aim of grappling questions relating to origins. The answers offered in the past, however, have proved wrong or at least inadequate. But humans continue to be curious about the world around them, in a way that sets them apart from all other creatures that inhabit the planet.

Now, in the year 2010AD, some of the answers to these most profound questions are beginning to emerge. We may even be on the threshold of unravelling our cosmic ancestry – discovering where we came from.

Big Bang and its aftermath

Astronomers are now confident that the material that forms planets, stars and galaxies arose in a "Big-Bang" event 13.7 billion years ago. Thus the age of the Universe is just a little more than three times the age of the Earth. We are young in the scheme of things, but perhaps not as young as we once imagined – when the Universe was thought to be of an infinite age.

The original material in the Universe was in the form of elementary particles, the nature of which is still to be fully understood. These elementary particles turned into atoms of hydrogen and helium that form the main constituents of the Universe. The other atoms of which planets and indeed life are made - carbon, nitrogen, oxygen, phosphorous, silicon ……. - were synthesised from hydrogen and helium in the nuclear furnaces in the deep interiors of stars, and were expelled into space by exploding supernovae. This leads to a stark conclusion: all the carbon, oxygen and nitrogen in our bodies, the calcium in our bones, the iron in our cars, were made in the deep interiors of stars. As Carl Sagan once put it "we are starstuff". The work that led to this conclusion was carried out in the 1950’s by three men and one woman: Fred Hoyle, Willy Fowler, Geoff Burbidge and Margaret Burbidge – a team that steered us unerringly towards understanding our cosmic heritage. It was Fred Hoyle and the present author who later continued this journey to become pioneers of the theory that life itself came from space.

Cosmic Genesis

But how did all this come about? How did "starstuff" – the atoms of life - turn into perhaps the most marvellous thing in the cosmos – life? Wherever and whenever the transformation from non-life to life occurred, several steps were involved. First, atoms must come together to form molecules. The right kinds of organic molecules must then be arranged into extremely specific configurations and structures such as DNA, proteins, ……and finally self-replicating cells that evolved into plants, animal, and humans.

To say that the transformation from non-life to life is extremely difficult is an understatement of astronomical proportions! If we consider the assembly of the basic building blocks of life into the right structures, the probability of life emerging, not just on Earth but anywhere in the cosmos – is utter minuscule, infinitesimal.

Think of the odds of winning a national lottery in any country where it is played. The probability of one single win is typically one chance in 10 million. The odds of life emerging de novo from non-life anywhere in the cosmos is like winning a national lottery not once, twice or thrice, but for well over 300 times in a row! This evidently insuperable difficulty has been commented upon by several scientists, and at times even offered as "proof" of a creator

Life debris are everywhere

The first positive identification of complex organic polymers (long chains of organic molecules) in cosmic dust clouds was proposed by the writer and published in the prestigious scientific journal Nature as far back as 1974. The contribution of Fred Hoyle and the present writer to the problem of the origin of life was to turn our attention away from "warm little ponds" on the Earth to the biggest available astronomical setting to understand how life might have arisen. The logic is that if we go to a big enough setting, even a near "impossible" event becomes "possible". We envisage a "pond" of cosmological proportions that transcends the scale of any pond or ocean on Earth by many, many, many powers of ten. Indeed a large part of the entire Universe might have been involved in the initial origin of life. But thereafter, we argue, the spread of life becomes inevitable and unstoppable.

On the Earth it is clear that life processes account for almost all the organic molecules on the planet. If biology can somehow be shown to be widespread on a cosmic scale, the detritus of living cells would be expected to be widely distributed in the Cosmos. The bulk of the organic molecules in space that have been discovered since the 1970’s would then be explained as break-up products of life-molecules. Inorganic processes can scarcely be expected to compete with biology in their ability to synthesize entire suites of biochemicals mimicking the detritus of biology. So wherever complex organics are found in an astronomical setting, one might legitimately infer that biology has been at work.

Spontaneous generation disproved

The notion advocated by Aristotle (384-322BC) was that life could arise spontaneously from everyday materials. According to Aristotle life originated in the form of fireflies emerging from a mixture of warm earth and morning dew! This came to be known as the doctrine of spontaneous generation, an idea that dominated science well into the 19th century.

Louis Pasteur in the early 1860’s claimed to have delivered a ‘mortal blow’ to spontaneous generation from his studies of silkworm diseases, the fermentation of wine and the souring of milk. Pasteur showed convincingly that bacterial activity was responsible for all these processes. What was known already for larger life forms - that life is always derived from pre-existing life of a similar kind - was now shown true for bacteria as well. Bacteria, always and everywhere, come from bacteria that existed before.

In 1987 the German physicist Herman von Helmholtz, responding to Pasteur’s discovery wrote thus:

"It appears to me a fully correct scientific procedure, if all our attempts fail to cause the production of organisms from non-living matter, to raise the question whether life has ever arisen, whether seeds have not been carried from one planet to another…"

If life has always been preceded by life, as Pasteur demonstrated, life did not have a beginning, Helmholtz suggested. We can go back generation by generation at least to the time of the origin of the Earth. And if the Pasteur logic is taken to its logical conclusion, life must have been derived from the matter that went to make the Earth, with the life present at this stage going back even further to a time close to the beginning of the Universe 13.7 billion years ago. This position, which was assiduously argued and developed by the present author and Fred Hoyle over three decades, is beginning to look more and more secure in the light of modern discoveries.

Formation of the Earth

Nearly 4,500 million years ago the Earth had just formed from the accumulation of smaller rocky bodies that were orbiting the sun. At this time its surface was far too hot for life or even organic molecules to survive. Comets containing water ice, organics and also, in our view, the cosmic seeds of life were now occupying the frozen outer regions of the solar system where the planets Uranus and Neptune were coming together. Some of these cometary bodies were deflected into the inner regions of the solar system and struck the Earth. Impacting comets brought water to form the oceans, and the evaporation of water from the oceans and the break-up of water molecules led to the formation of an atmosphere and a cloud cover around our planet. It was only then that our planet became a congenial home for life.

The moment of the first appearance of life on the Earth has been pushed further and further back in geological history, to as far back as 4,000 million years ago. This is possibly the first moment that life could have survived on Earth, and it comes as no surprise that life’s first arrival coincides with a period of intense bombardment by comets; thus forcing the conclusion that life came along with the material that comets brought to the Earth.

Bacteria fit for space

The discovery of microorganisms occupying the harshest environments on Earth continues to provide indirect support for this point of view. Viable transfers of microbial life from one cosmic habitat to another require endurance of high and low temperatures as well as exposure to potentially lethal cosmic rays. Quite remarkably the survival of microorganisms under such extreme conditions is well documented. Dormant microorganisms in the guts of insects trapped in amber have been revived and cultured after 25-40 million years; and a microbial population recovered from eight million year old ices has shown evidence of surviving DNA. There are bacteria that can endure extremely high radiation doses (some thrive within nuclear reactors), extremes of cold and heat as well. Bacteria thus appear to be endowed with properties that make them just right for space travel.

Astronomical studies of comets, interstellar dust clouds in our own galaxy, as well as in distant galaxies, are all converging on the conclusion that microbial material and their degradation products are everywhere in the cosmos. Our microbial biosphere extends to the remotest corners of the cosmos. Nearer home we are discovering evidence that comet dust and comet fragments (meteorites) contain evidence of both dead and living microorganisms.

Life on other planets

According to our theory the genetic components that led to life on Earth are omnipresent in the galaxy, so the same or similar genes that arrived here would also arrive at the surfaces of countless other planets. Every niche in every habitable planet in the galaxy would then be colonized thus leading to the widespread occurrence of microbial life. The fraction that eventually evolves into higher life is debatable, but with identical genes delivered to a multitude of similar environments and planetary niches a convergence of evolutionary patterns could be expected. In terrestrial life for instance, it could be argued that the evolution of the eye was achieved independently at least thrice. Intelligence of the kind humans possess may have some survival advantage in that a greater capacity to understand our environment may lead to greater skills at manipulating it to our advantage. On this basis, high levels of intelligence could be understood as a cosmic evolutionary imperative.

It would also be unwise to regard ourselves – homo sapiens sapiens – as the culmination of this evolutionary process. With just a few million years of human evolution the "experiment" of intelligence may have scarcely begun on Earth, and greater things may well lie ahead. In the cosmic context creatures endowed with much higher levels of intelligence than ours could indeed be commonplace.

Habitable alien planets

How many habitable planets are there in our Galaxy? In the last few years astronomers have discovered a total of about 500 planets orbiting nearby stars. All these are relatively nearby, less than 100 light years away from us. The star Epsilon Eridani which is 10 light years away not only has planets, but also belts of asteroids and comets orbiting around it. It seems probable that 25% of stars like our sun are endowed with planets, and at a reasonable guess one might expect to find a total of a billion habitable planets in the galaxy – planets that can maintain liquid water at the surface and support primitive life.

Intelligent life

How many planets are there in the Galaxy where life has evolved to produce intelligent creatures, and technological civilizations capable of space travel?

It can be calculated, using reasonable assumptions, that the number of such planets is equal to about one fifth of the number of years that an intelligent civilization will be expected to last.

Using our solar system model, the upper limit would be determined by the average time interval between devastating comet impacts, which for the Earth is about 50-100 million years - thus giving a maximum of 10 to 20 million planets endowed with intelligent life. But more realistically the duration of an advanced technological civilization would be shorter. Our human experience on Earth over the past century does not give much confidence for choosing a higher value of lifetime, say, greater than say 500 yr. In this case (according to our rule) we come up with a grand total of only 100 advanced intelligent civilizations in the Galaxy, and the prospect of any alien contact or communication will be slim.

Such pessimism about our inability to survive is based on the simple fact that the nuclear arsenals in the modern world have enough fire power to extinguish all life on the planet; and it is difficult to imagine that this would not be an eventual outcome. However, if the next stage in the evolution of intelligence is to adopt a Buddhistic philosophy of non-violent co-existence, then it could be that the average lifetime of a civilization will be higher. For argument’s sake, taking the lifetime of a civilization to have an optimistically high value of 100 million years, the number of planets endowed with intelligent life becomes 20 million, and their mean separation in the Galaxy turns out to be about 30 light years. If we are optimistic in imagining space-faring aliens to be able to travel at three percent of the speed of light, the average crossing time between adjacent civilizations will be 1,000 years.

Let’s suppose our super-intelligent alien neighbours have an average generation time of 100 years – three times higher than a human generation. This could not be far wrong according to the ideas of convergent evolution. Our potentially nasty neighbours setting out to colonize and threaten Earth would take tens of generations to reach their target planet. Would any intelligent civilization embark on a voyage of conquest where only great, great, great……grand progeny reach their promised land? This would not be consistent with any reasonable extrapolation from human psychology or predator-prey models applicable to lower life forms.

Colonization of a galaxy via the process of "directed panspermia" such as was proposed in 1973 by Francis Crick offers a much better prospect. An advanced technological civilization, perhaps facing the prospect of imminent extinction, may well decide to package its genetic heritage within microbes and launch them out into space. No expensive rocket system is needed. The genetic packages are of just the right sizes for their propulsion by the radiation pressure of starlight to be guaranteed. Although a large fraction of our space-travelling genes might perish in transit, the reassembly of the surviving genes that reach habitable planets would lead indirectly to galactic colonization.

Alien diseases

The real risk to humanity of alien life may be in the form of bacteria and viruses arriving at the Earth which are sometimes pathogenic. Fred Hoyle and the present author have argued the thesis of "Diseases from Space" over several decades. Despite criticisms that have often been made against this concept the basic arguments remain cogent to the present day. With increasing evidence to support the view that life could not have arisen indigenously on the Earth, the idea that the evolution of life is modulated by genes arriving from comets has acquired a new significance.

The record of such genetic additions exists even now in our DNA. The human genome has recently been mapped in its entirety and found to contain more than 50 percent of in the form of well-defined viral genes. It is only possible to understand this if our ancestral line over a few million years had suffered a succession of near-culling events following devastating outbreaks of viral disease. On each such occasion a small breeding group survived and its members assimilated the virus into their reproductive line.

In conclusion, we note that the aliens we have to fear are not super-intelligent creatures arriving in space ships threatening to conquer us, but sub-micron sized viral invaders that may threaten the very existence of our species.

Through the vicissitudes of epidemics and extinctions our own alien ancestry has come to be locked into our genes; but the ultimate origin of all life is lost in the mists of cosmic time.

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