Life in the Cosmos

Life in the Cosmos

There must be many different environments suitable for life in a given planetary system. Once life originates, it tends to be very adaptable and tenacious.

In the Solar system there are several bodies that may be suitable for life of some art: the Earth certainly (if we all live in a real world and not in a computer simulation), and perhaps Mars, Titan and Jupiter.

There is evidence that planets are a frequent accompaniment of star formation. We can see this evidence in the satellite systems of Jupiter, Saturn and Uranus, which are like miniature solar systems. Theories of the origin of the planets are based on this premise and studies of double stars confirm it. We can also observe accretion disks around stars and find the evidence in some preliminary investigations of gravitational perturbations of nearby stars.

Thus many, perhaps even most stars in our universe must have planets.

But what about life? All experiments show that under the most common cosmic conditions the molecular basis of life is readily made, the building blocks of molecules able to make copies of themselves.

We step now on less certain ground: there may be impediments in the evolution of the genetic code, although we think this unlikely over billions of years of primeval chemistry.

On the one hand, many individually unlikely steps had to occur in biological evolution and human history for our present intelligence and technology to develop. There must be many quite different pathways to an advanced civilization of specified capabilities.

On the Earth we must consider the apparent difficulty in the evolution of large organisms represented by the Cambrian explosion. Thus let us suggest that only one percent of planets on which life arises eventually produce a technical civilization.

The conclusion in interesting enough: the total number of planets in the Milky Way only on which life has arisen at least once may be a hundred billion inhabited worlds. And we repeat that we speak about the Milky Way only. That in itself is a remarkable conclusion. But we are not yet finished. One percent of plants where a technical civilization has developed, give us the total number of one billion “civilized” worlds.

Obviously, this estimate represents some middle ground among the varying scientific opinions.  Some think that the equivalent of the step from the emergence of trilobites to the domestication of fire goes like a shot in all planetary systems. Some other think that even given ten of fifteen billion years, the evolution of even ten technical civilizations in the Milky Way Galaxy is unlikely.

Anyway, this is not a subject on which we can do much experimentation as long as our investigations are limited to a single planet. Our estimation about a billion planets on which technical civilizations have arisen at least once is rather speculative. It is very different from saying that there are a billion planets on which technical civilizations now exist. For this, we must know much more about Cosmos.

How many technical civilizations exist in the Universe? We know for sure about only one by now. Image : Megan Jorgensen.

Erosion on the Earth

Erosion on the Earth

Because of erosion on the Earth, our monuments and artifacts will not, in the natural course of things, survive to the distant future. But the spaceships Voyager launched in the XX Century carry human records on their way out of the Solar system.

Indeed, brains and genes and books encode information differently and persist through time at different rates. But the persistence of the memory of the human species will be far longer in the impressed metal grooves on the Voyager interstellar record. It happens because the erosion in interstellar space – chiefly impacting dust grains and cosmic rays – is so slow that the information on these recordings will last a billion years.

But the Voyager message is traveling with agonizing slowness. The fastest object ever launched by the human species, this probe will still take tens of thousands of years to go the distance to the nearest star.

Any television program will traverse in hours the distance that Voyager has covered in years. A television transmission that has just finished being aired will, in only a few hours, overtake the Voyager spacecraft in the region of Saturn and beyond and speed outward to the stars. If it is headed that way, the signal will reach Alpha Centauri in a little more than four years. If, some decades or centuries hence, anyone out there in space hears our television broadcasts, I hope they will think well of us, a product of fifteen billion years of cosmic evolution, the local transmogrification of matter into consciousness.

Our intelligence is providing us with awesome powers, but it is not yet clear yet if we have the wisdom to avoid our own self-destruction.

However, many of us are trying very hard. We hope that very soon in the perspective of our cosmic time we will have unified our planet peacefully into an organisation cherishing the life of every living creature on it and will be ready to take that next great step, to become part of a galactic society of communicating civilizations.

Will we ever become part of a galactic society? Image : © Megan Jorgensen.

Illegal Radio Transmissions

Illegal Radio Transmissions

or Million Years Old Society

A technical civilization one million years-old has descended on the planet Earth… Would we even recognize its presence?

More important question yet: Would a society a million years in advance of us be interested in colonization or interstellar spaceflight?

In fact, it may be people have a finite lifespan for a reason. Could it be that we are so interested in spaceflight because it is a way of perpetuating ourselves beyond our own lifetimes? Of course, progress in the biological and medical sciences might uncover that reason and lead to suitable remedies.

But might a civilization composed of essentially immortal beings consider interstellar exploration fundamentally childish? It may be that we have not been visited because the stars are strewn abundantly in the expanse of space, so that before a nearby civilization arrives, it has altered its exploratory motivations or evolved into forms indetectable to us.

It would be very easy for extraterrestrials to make and unambiguously artificial interstellar message (provided that they have the same logic we have and the same mathematics, which is reasonable enough if they try to make a contact with their neighbours). For example, they could first prime numbers – numbers divisible only by themselves and by one – are 1, 2, 3, 5, 7, 11, 19.

It is extremely unlikely that any natural physical process could transmit radio messages containing prime numbers only. If we received such a message we would deduce a civilization out there that was at least fond of prime numbers. But the most likely case is that interstellar communication will be a kind of palimpsest, like the palimpsests of ancient writers short of papyrus or stone who superimposed their messages on top of pre-existing messages.

Because we will share scientific and mathematical insights with any other civilization, understanding the interstellar message coming from a very advanced cosmic community will be the easiest part of the problem. Convincing the governments to fund a search for extraterrestrial intelligence is the hard part.

In fact, it may be that civilizations can be divided into two great categories: one in which the scientists are unable to convince non-scientists no authorize a search for extraplanetary intelligence, in which energies are directed exclusively inward, in which conventional perceptions remain unchallenged and society falters and retreats from the stars; and another category in which the grand vision of contact with other civilizations is shared widely, and a major search us undertaken.

This is one of the few human endeavors where even a failure is a success. If we were to carry out a rigorous search for extraterrestrial radio signals encompassing millions of stars and heard nothing, we would conclude that galactic civilizations were at best rare, a calibration of our place in the universe. It would speak eloquently of how rare are the living things of our planet, and would underscore, as nothing else in human history has, the individual worth of every human being.  If we were to succeed, the history of our species and our planet would be change forever.

Perhaps at an adjacent frequency or a faster timing, there would be another message, which would turn out to be a primer, an introduction to the language of interstellar discourse. The primer would be repeated again and again because the transmitting civilization would have no way to know when we tuned in on the message. And then, deeper in the palimpsest, underneath the announcement signal and the primer, would be the real message. Radio technology permits that message to be inconceivably rich. Perhaps when we tuned in, we would find ourselves in the midst of Volume 6,511 of the Encyclopaedia Galactica.

Any messages transmitted from outer space are the responsibility of the BBC and the Post office. It is their responsibility to track down illegal broadcasts (pronouncement from a British Defense Department, the London Observer, February 26, 1978). Image : Megan Jorgensen.

Why Do We Go to the Stars?

Why Do We Go to the Stars?

If our Sun or a nearby star were about to go supernova, a major program of interstellar spaceflight might suddenly become attractive, In fact, the discovery that the galactic core was imminently to explode might generate very serious interest in transgalactic or intergalactic spaceflight. Such cosmic violence occurs sufficiently often that nomadic spacefaring civilizations may not be uncommon.

However there may be many other motivations to go to the stars: an emerging technical civilization, after exploring its home planetary system and developing interstellar spaceflight, would tentatively begin exploring the nearby stars.

Some of these stars would have no suitable planets – perhaps they would all tiny asteroids or giant gas worlds. Others would carry an entourage of suitable planets, but some would be already inhabited, or the atmosphere would be poisonous or the climate uncomfortable.

In many cases the colonists might have to change –or as we would parochially say, terraform – a world to make it adequately clement.

The re-engineering of a planet will take time, but suitable world would be found and colonized. 

The utilization of planetary resources so that new interstellar spacecraft could be constructed locally would be a slow process. Eventually a second-generation mission of exploration and colonization would take off toward stars where no one had yet been. And in this way a civilization might slowly wend its way like a vine among the worlds.

It is possible that at some later time with third and higher orders of colonies developing new worlds, another independent expanding civilization would be discovered.

Very likely mutual contact would already have been made by radio or other remote means. The new arrivals might be a different sort of colonial society.

Conceivable two expanding civilizations with different planetary requirements would ignore each other, their filigree patterns of expansion intertwining, but not conflicting. They might cooperate in the exploration of a province of the Galaxy. Even nearby civilizations could spend millions of years in such separate or joint colonial ventures without ever stumbling upon our obscure solar system.

A million years is a very long period of time, but we could manage… (Cosmos by Carl Sagan). Image: © Megan Jorgensen.

Transmissions for Sale

Transmissions for Sale

To learn a little about what other kinds of civilizations are possible, we can study history and cultural anthropology. But we are all of us - us whales, us apes, us people – too closely related. As long as our inquiries are limited to one or two evolutionary lines on a single planet, we will remain ignorant of the possible range and brilliance of other intelligences and other civilizations.

Thus we are looking for other intelligences using different means and methods. For example, we suppose that most of other civilization will use powerful sources to transmit their notions and ideas. Some of our most powerful sources are radar transmitters; a few are used for radar astronomy, to probe with radio fingers the surfaces of the nearby planets.

As the Earth rotates, our more powerful radio transmitters slowly sweep the sky. A radio astronomer on a planet of another star would be able to calculate the length of the day on Earth from the times of appearance and disappearance of our signals. The size of the radar beam projected against the sky is much larger than the size of the planets, and much of the signal wafts on, out of the solar system into the depths of interstellar space to any sensitive receivers that may be listening.

On Earth, most radar transmissions are for military purposes as they scan the skies in constant fear of a massive launch of missiles with nuclear warheads, and augury fifteen minutes early of the end of human civilization. The information content of these pulses is negligible: a succession of simple numerical patterns coded into beeps.

Overall, the most pervasive and noticeable source of radio transmissions from the Earth is our television programming. Because the Earth is turning, some television stations will appear at on horizon of the Earth while others disappear over the other. There will be a jumble of programs. These might be sorted out and pieced together by an advanced civilization on a planet of a nearby star.

Large-scale television transmission on the planet Earth began only in the late 1940’s. There is no calling those television programs back. There is no way of sending a faster message to overtake them and revise the previous transmission. Nothing can travel faster than light.

Thus, there is a spherical wave front centered on the Earth expanding at the speed of light.

Because these transmissions were broadcast a few decades ago, they are only a few tens of light-years away from Earth. Hum… the most frequently repeated messages will be and appeals to purchase detergents, headache tablets, deodorants, automobile and petroleum products.

The most noticeable messages will be those broadcast simultaneously by many transmitters in many time zones – for example, speeches in times of international crisis.

If the nearest civilization is about 100 years away, then we can continue to breathe easy for a while. In any case, we can hope that they will find these programs incomprehensible.

The mindless contents of commercial television and the integuments of international crisis and warfare within the human family are the principal messages about life on Earth that we choose to broadcast to the Cosmos. What must they think of us? Image : © Megan Jorgensen.