We scan the skys for evidence of other life on other planets. Yet, if "they" were there, wouldn't we already know it?
I stumbled upon the following in a site that provides views of Earth and Luna, as well as a "Random New Earth" each day.
You will find the following here, if you scroll down past all the UNIX "incantations".
The ideas provided here and at that site are for some hopefully lively discussion, not to trample on anyone's beliefs, hopes, or dreams. So let's not digress into a flame war, please.
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There are no other intelligent species, certainly not in our galaxy and probably not anywhere in the universe. This is the inescapable conclusion from the Fermi paradox.
Amateur astronomers hoping to share their love of the sky sometimes speak of "the friendly stars". Certainly anyone who comes to really know the sky cannot look upward without seeing old friends visited before, friends to call on again and again, whether with a telescope, binoculars, or just lying in a grassy field on a warm spring evening, taking in the heavens with that venerable instrument, the human eye.
Yet learning more about the universe makes it seem, in many ways, less friendly. For the stars are not lamps hung in the sky to guide us at night, but raging nuclear furnaces separated by emptiness so immense our minds cannot grasp its extent. To study astronomy is to encounter violence beyond the human experience: stars which explode, incinerating their planets, or burn out into eternally dark cinders; sources of radiation so intense they outshine whole galaxies, powered by black holes that swallow entire stars; gravity that crushes atoms into subatomic particles or into nothingness; whole galaxies that explode, collide with one another, and devour their neighbors; a universe born in a creation fire still glowing today and destined—we know not which—either to collapse and be crushed from existence or expand into an eternity of darkness and cold. Awesome it is to contemplate, but awful in its seeming hostility to life.
Awesome because what we discover in the sky seems so alien to our own experience. Awful because to look at the sky is to ask, in the larger sense, "What is my place in the universe?". We look upward from a small globe teeming with life and see an endless void: empty, lifeless, and violent. To learn that not just one's own personal existence, not just all of humanity's experience, but that life itself appears insignificant and irrelevant to the universe is to stand humbled under cold and unfriendly stars.
Look upward to the Sky; look downward at the Earth. Upward, blackness punctuated by points of fire, worlds by the dozens in our neighborhood, and all of them lifeless. Downward, a globe not just home to a multitude of living creatures, but fashioned by life: its life-sustaining atmosphere itself created and maintained by life. Earth is not merely home to life; in a real sense it is alive, but alone.
But are not the stars home to other forms of life, perhaps other intelligent species already sensing our electromagnetic birth cry and preparing to welcome us into the galactic community? Almost certainly not: there is every reason to believe we are alone in the galaxy, and perhaps in the universe.
The meaning of life is to live. To live is to expand the scope of life itself, by replicating, by adapting, by modifying the environment, and by evolving into other forms of life. We are the inheritors of more than three billion years of ceaseless global molecular experimentation, of competition among individuals and species, of a relentless expansion of life into new environments and emergence of new capabilities. How can we have the arrogance to believe, so recently evolved ourselves to a stage that we can truly be said to think, that we are unique—that no other intelligent beings see our Sun as a star in their sky and, as arrogantly, consider themselves unique?
It was physicist Enrico Fermi who first remarked, "If they existed, they would be here". Life expands its own scope. Life on Earth extends from the mid-oceanic ridges where the Earth's very crust is born, to the peaks of the highest mountains and the most remote regions of the Antarctic. In the span of one human lifetime, transcending the limits of our bodies through the cleverness of our minds, our own species has descended to the deepest points in the ocean, visited the most remote places on the planet, learned to fly in the air and then beyond into space, and on July 20, 1969 set foot on another world which had never before been host to life. Products of billions of years of ever-expanding life, the very molecules of which we are made drive us to spread life ever further. Already, our robot proxies have visited all the major worlds of our solar system, seeking life and finding none.
Is it reasonable to expect that life will cease to expand at the very moment it becomes capable of spreading further, outward, onward? That after billions of years and countless quadrillions of organisms, life will remain huddled on one small planet, awaiting the day when the Sun dies and ends it all? No. Already we have taken our first steps outward. Once the expansion begins in earnest, it will spread exponentially. It took three billion years of evolution before life managed to assemble individual cells into complex creatures, then only a quarter as long to evolve beings capable of carrying life to other worlds. Using only technologies we currently possess, and traveling no faster than the Voyager probes already bound starward, we could begin to explore the galaxy. Even at so slow a speed—requiring between ten and a hundred thousand years to travel between stars, if each new outpost launched its own emissaries of life onward, life would spread everywhere in the galaxy in only 300 million years—less than half the time it took the first multicellular creatures to evolve into beings audacious enough to think such thoughts. Using technologies likely to be developed in the next century, founded on scientific knowledge already in hand, life could populate the galaxy in just 4 million years—comparable to the time it took the first hominids to radiate from the Home Continent to the farthest corners of the Home Planet.
Four million or even three hundred million years is an eyeblink of time compared to the 10 billion years elapsed since the galaxy reached the stage where beings like us could develop. If intelligent life is common then why, over the billions of years that preceded our appearance, has no species evolved earlier already filled the galaxy?
"If they existed, they would be here", said Fermi. So where are they? Nowhere in evidence. Intelligent beings with technologies advanced millions of years beyond our own, spread to the far ends of the galaxy, should not be difficult to detect. We already possess the means to detect even primitive technological civilizations like our own at a distance of hundreds of light years.
If they existed, they—the first intelligent species to expand outward among the stars—would be here. And since we look around and see nobody but ourselves, then it is only reasonable to conclude, "We are here, so we are them." We evolved here and we have not yet begun to sow the seeds of life among the stars, but surely we will. Three billion years ago, one planet, the Home Planet, came to life. Slowly life spread across the Home Planet, gaining complexity and diversity until it could think of going yet further.
In a short time on the cosmic scale, beings throughout the galaxy will gaze at the friendly stars in their skies. They will look upward and see, not a hostile and lifeless galaxy, but one teeming with life—the legacy of the planet that came to life and then brought life to a galaxy. They will not be human, no more than we are Australopithecus or fish or bacteria, yet they, in their number and diversity trillions of times beyond the scope of life on Earth, will be our children, inheritors of our coming to understand the meaning of life and the role we humans are to play in its grand pageant.
Ref. article “Enrico Fermi” by Lawrence Badash, Encyclopædia Britannica Online, http://www.britannica.com/EBchecked/topic/204747/Enrico-Fermi:
“During his later years he raised a question now known as the Fermi paradox: ‘Where is everybody?’ He was asking why no extraterrestrial civilizations seemed to be around to be detected, despite the great size and age of the universe. He pessimistically thought that the answer might involve nuclear annihilation.”
Possibly so – or budgetary reasons, or manners good enough so as not to multiply like rabbits around all the Galaxy, or whatever.
Or considering life more generally: there might at this very moment be a large molecule somewhere at the other side of the Milky Way saying, “Eureka, I just found out how to make a copy of meself!” Or maybe he or she or it said it three billion years ago next Wednesday, and is presently busy inventing radio. Or perhaps his or her or its radio signals were sent already 150,000 years ago, and will be found in the next SETI@home work unit to be crunched by some two guys of us.
Enrico Fermi’s question may be justified, but I fail to see how it could be a proof of anything. I feel there is even no need to be guessing, whether extraterrestrial life exists or not, or whether possible extraterrestrial life would be intelligent enough to be contactable. We may just take a look into these and related matters the best way we can. These SETI and SETI@home projects do make sense in this regard.
Well, somebody might want to see another Encyclopædia Britannica Online article, too: “extraterrestrial life” by Carl Sagan, Lynn Margulis and Dorion Sagan, http://www.britannica.com/EBchecked/topic/199123/extraterrestrial-life. There’s even an image of SETI@home screen saver, and a particularly wise paragraph in the end of text:
“Although there is only an infinitesimal possibility that humanlike beings will be discovered in outer space (to serve as a cosmic example of convergent evolution), the discovery of any other living matter anywhere else in the cosmos would be of the utmost scientific significance. Moreover, if no evidence at all for life beyond Earth is found after a significant search, this too would be of great scientific moment. The absence of the evolving matter-energy flow systems that are life would reinforce the awesome responsibility of protecting its diversity in this biosphere, which includes that precious, cosmically fragile, and recent growth form, human civilization.”