This issue of Musea contains 3 essays on life: 1. Where is it? 2. What is it?
and 3. Discuss Amongst Yourselves.
Join me in investigating the biggest biosphere of all - our universe!
Where Is It? Zoning Laws for Life OR what would aliens know about us before they even get here.
"Life was an accident. There was little doubt of that. Something that wasn't exactly planned. Something that had crept in, like a malignant disease in the ordered mechanism of the universe. The universe was hostile to life. The depths of space were too cold for life, most of the condensed matter too hot for life, space was traversed by radiations inimical to life. But life was triumphant. In the end, the universe would not destroy it ... it would rule the universe." Cosmic Engineers by Clifford D. Simak.
You'd think with all the stars out there , there would be life everywhere. For instance, if it wasn't for the obscuring dust in space we would be able to read at night by the light of the Milky Way! Let's go through the vastness: our earth is one of many planets in our solar system, our solar system is in a spiral arm of the Milky Way galaxy, our galaxy is one of 31 in the local group of galaxies, with two major ones - ours and Andromeda. The local group is part of the Virgo local supercluster of galaxies with about 2,500 galaxies, and beyond that there seems to be plenty of superclusters too, spread out evenly across the universe. Pretty vast huh?
So surely there is life calling from somewhere out there right? I mean you'd think that with all those possibilities for life to start, it would be popping up, dialing up, and coming down for a landing from every quadrant of the sky. American radio astronomer, Frank Drake, devised the Drake equation, seven factors that derive the number of civilizations in the Milky Way (our galaxy alone) that are able and willing to transmit and receive radio signals. Here it is: N, number of communicating civilizations = rate of starbirths - 10 per year, stars with planets - 1 per solar system, planets with life supporting environments - 1, planets with life - 1, intelligent life - .1 or 1 in 10, communicating societies, - .1 or 1 in 10, civilization life span (or the "we blow ourselves up in this many years" factor) - 1,000 to 1 million years.
The values were guesstimated in 1961 as being from 100 to 100,000,000 civilizations (in our galaxy alone - don't forget galaxy - then local galaxy group, then....) BUT Look carefully. If you were an alien (or an astute, cogitating earthling), you'd know that life probably has a much, much, MUCH, more narrow window of opportunity than most stargazers have ever considered. Let's delve deeper and see why that may be, in a section I call "The Narrow Window of Life!" - I like the sound of that - sort of like a soap opera.
The Tommy equation for life is a little different than Drakes. Here goes.
1. Time. Yes, time rules out a big chunk of the universe. You see, the Big Bang (the pow! BIFF! Bazoom! that started our universe) probably started it all around 13? (10-20) billion years ago. Yet physics-wise that was first, a burst of radiation (so great that the snow on a blank TV screen is the remnant of that bang = 3 degree K background radiation) that cooled to complete darkness as it continued to expand. Will it expand forever? Good question class! ...
Then the mostly hydrogen and helium gases began to collect due to gravity. As things became more concentrated they became more hot and fiery and all at once little beacons or lanterns of light went off, and stars were turned on across the universe. Light had emerged from darkness. Some brash stars - as young whippersnappers often do - spent all their energy quickly (nuclear fusion) and blew up in supernova explosions that sent wastes of heavier elements into the universe like carbon, and oxygen. Thus these stars were like furnaces to make heavier elements needed for life. Our Galaxy was probably formed about 10 billion years ago and the sun was formed about 5 billion years ago, and the earth 4.5 billion years ago.
Finally, here is my point among the data. It took a long, long time for helium and hydrogen to gel into chemicals cool enough for life to evolve from - like carbon and oxygen. In our case it took from the big bang at 13(?) billion years ago) - to 5 billion years ago before our solar system could even start forming - let alone life on Earth. That means that in our case it took 8 billion years (13-5=8) to get some heavy elements. Heavy indeed! So life, which needs carbon and water (see later), would have to wait in the wings for the first 8 billion years. That cuts the alien-making time in at least half right there! So all us life forms had to wait for 2nd generation elements to form.
2. Galaxies are not uniform at all. In ours, the Sun/solar system is on the inner edge of a spiral arm called Orion. But it is also so close to the next spiral as to almost be on the outer edge of the Sagittarius arm. They seem to almost bump each other. The orbit of Sun around the center of the galaxy seems to be nearly circular (like the earth around the sun). But not all stars in this or any galaxy are set up for life. Within the galaxy are older red stars towards the center and younger blue stars towards the edge. In the Discover article called Circles of Life (Nov. 2002,) they say life may not be able to exist too near the center of a galaxy: "The stars are so dense there that they may give off too much radiation and cause too many gravity-perturbing collisions to support life. Stars too far from the center may contain too few metals to make planets massive enough to hold on to an atmosphere. The sun sits right in between these extremes." Sweet!
That suggests an amazingly small window of opportunity in any galaxy. Also it suggests that life would be nearer the rim of these galaxies and thus widely separated. In our galaxy we are in one spiral arm. The distances to similar sections of other spiral arms is immense.
3. Our solar system orbiting around the sun, our star, shows evidence of how it was made. Revolving around the new sun was a disc of matter. Nearest the sun were heavy metals because they weigh more and the Sun's massive gravity held them closer. These collided together to form the heavy rock planets of Mercury, Venus, Earth, Mars, and assorted asteroids. Then beyond are the lighter gas giants of Jupiter, Saturn, Uranus, and Neptune. And finally the out of orbit and out of line, tiny Pluto which doesn't fit much of anything. Anyway, aliens would know where the life would be in this line up because for life to form it has to:
a. Have a certain atmosphere
b. Be a certain distance from its star
Now lets look at these 2 conditions.
A. Have a certain atmosphere. The earth, due to its size, has a specific amount of gravity. This amount holds in a specific atmosphere. Smaller sized planets like the Moon, or Mercury can't hold in any gases - they just float away. Larger-sized planets hold in life-prohibiting gasses. Jupiter, Saturn etc. hold in too much. Earth holds in some, but not others. Example: most released hydrogen, the lightest gas, probably sailed into space long ago never to return.
And if we are left with a specific gravity for all planets with life, then that means that all life will exist within a certain range of size that can exist in that gravity. On our planet that is viroids to blue whale size. It should then be the same limits for other planets with life. [Also note the earth is large enough to retain volcanic activity and internal heat. That may be important, too.]
B. Be a certain distance from its star. Life needs water - not ice, not steam (well maybe steam - the jury is still out). But liquid water is just right, as Goldilocks might say. And for water to be liquid the temperature must be within the range of 0-100C which in 'F' language is freezing at 32 F to boiling at 212 F. But to get that temperature, you've got to be just the right distance from your heat source - the sun. Too far and you're barren Mars, too close and your Hothouse Venus. The earth's orbit is just right. "In our solar system, the zone's inner limit is just outside the orbit of Venus; its outer edge is near Mars. Whether the Red Planet is inside the zone is still a matter of debate." (Discover again). Also note the circular orbit of Earth that keeps the temperature cycle 'wet' or in liquid water territory, almost all the time. If the orbit was more oblong, it may have been too hot then too cold; or, too much for life to adjust to. And note this, with the temperature of all life planets similar, the chemistry of all life should be similar. Thus, those aliens have the same carbon chemistry we do.
Summary so far. We see that aliens looking for life (or us exploring out there) will know that already there is a narrow window of opportunity that includes:
1. A certain time zone in the history of the universe
2. Certain place zones in each galaxy
3. A certain place zone in each solar system. But that isn't all.
Gaia. NASA didn't much like to hear what James Lovelock was saying. He was spoiling their funding for trips to Mars. Lovelock was saying that he knew there was no life there from studying the planet's atmosphere from here. He said that we know if a planet has life by its atmosphere. The chemistry of a living planet is different from a dead planet due to the fact that a planet full of life would cycle through the elements through its numerous food-in and waste out cycles. Mars has a stable atmosphere of non-reactive gases while Earth has an atmosphere mixture that shows that life chemistry is hopping. Lovelock also went on to suggest a Gaia hypothesis: That life bearing planets regulate themselves on a global scale. The basic chemistry of life effects the entire planet! Therefore any space travelers can tell if life is on a planet by checking its atmosphere.
Moon. Could having a moon be a requirement for a planet having life? I tend to think it might. A visitor from space would label Earth/Moon as a dual planet system because our Moon is so similar in size to Earth (as compared to other moon/planet systems). The current best scenario for how the Moon was formed is in good part by William K Hartmann (who I have written to and received comments from - name dropping here). He says that a planetoid about the size of Mars smacked into early earth, tore off a sizable chunk of it that sprayed into space with a lot of dust and debris, and caused all kinds of planetary havoc. The chunks and debris circling earth, coalesced into our Moon that began to circle Earth very closely. Slowly it began to pull away from Earth and widen its orbit - which it continues to do even now. But Earth was affected too. The hit from the planetoid tilted the Earth - thus our seasons. Also with the impact and a Moon orbiting so close, it spun the earth around faster. Days were 3 hours long, nights 3 more. Also there were massive tides, and maybe some of our early atmosphere was blasted off too. Note how Venus, with no Moon, has an oppressive atmosphere with a crushing surface pressure about 95 times that of Earth at sea level, and a temperature of 800 F which is about the temperature of the side of Mercury that faces the Sun! Our Moon may have saved us from some of that (though critics say Venus is closer to the Sun - thus its position was the sole cause of its atmosphere) If having a planetoid strike Earth AND form a Moon sized moon, was a requirement for life here - then life is rare indeed because there was a lot of fluke in the making of our Moon!
Earth's first days. Hot Hot Hot. Hot and turbulent. The planet was cooling and volcanoes and cracks in the slowly forming crust allowed gases to escape. One of the most important was H2O - water vapor - ocean stuff. Some water may have come from comets (dirty snowballs) but most was from the volcanic behavior of Earth. And oceanographers note that the sea floor bed is filled with mounds everywhere - remnants of old volcanoes! There was also oppressive CO2 in the air (and no O yet. We breathe oxygen, but that gas is not a part of first life at all - it is so deadly it would have kept life from starting! It came billions of years later from photosynthesizers. So note that any first life lab experiments must first get the O2 out!) The heavy CO2 atmosphere would cause so many clouds that the sun could not even shine through (and all us poets and painters are missing that up close Moon!). As the Earth cooled and the bombardment of rocks from space (see Moon craters for evidence of this period) slowed down, water vapor turned to rain, which did some magical things. The rain began to take CO2 out of the air, form the earth's crust from seas of cooling lava, start the oceans, and for the first time, let the sun shine through. It is hear that I think was the window of opportunity for life to begin. It had all the goodies needed: sunlight, UV, water, a hot/cold cycle (day/night) and chemicals that were forming into basic building blocks of life. Sweet!
The key experiment in this area was done by Stanley Miller in 1953. He recreated this atmosphere and these conditions in a test tube, and though no life crawled out, the first building blocks of life - some amino acids - did. Origin of life chemistry had its origin. Yet before we leave this, note how narrow a period life had to begin on forming earth. I contend that it had to be at the high end of liquid water - and some beyond (say 70-120C), and that the sun had to shine through, and that the atmosphere had certain gases. IF that is correct, then even on earth the window of opportunity for life, was slim. BUT I also contend that once you got that far and all these requirements were met - THEN life was inevitable.
More Clues. Before I end this essay, I want to list some more clues that our alien visitors or more likely aliens trying to communicate to us over the vast, vast distances of space , OR us communicating to them; will know.
1. Life is carbon chemistry. The big name for it is organic chemistry. But in every case it is carbon compounds. Carbon has magical properties. Like most life chemicals (there are only a few main ones. I remember them as the word CHON = Carbon, Hydrogen, Oxygen, Nitrogen) , it is one of the most common elements. But it also has the property of making immense number of compounds in many different ways. No element is as flexible. Some sci-fiers suggest silicon. Most say nope. Silicon oxygen bonds are so strong that they rarely react with other compounds - thus like in a maze we hit a wall and can go no further with silicon. So aliens just about have to be carbon based life forms too.
2. Life looks like us Earthlings. (Note I use the term earthlings in the broader sense - bears, oaks, jellyfish and bacteria are Earthlings too). The reason aliens will probably look like us is because their gravity is the same, they have liquid water (oceans and seas), their atmospheres are similar (same skies), and if they have land that will be similar. AND there are only certain ways you can adapt (an evolutionary term) to those environments if you are a living thing. Ex. All fliers, flying animals, have relatively the same aerodynamic forms, all swimmers have the best gliding-through-water shapes, all land crawlers (or underground burrowers) have the same basic design. Thus for any life to adapt to its environment, it'll end up looking somewhat the same. (In bio-talk this is convergent evolution. It is a term for like-minded earth creatures, but it should work for other planets too). A good example of this from our own history is these 3 swimmers: ichthyosaurs, sharks, and dolphins. They all developed at different eras in our history - but they all have almost the identical sleek swim-through-the-sea, shape.
3. Speed of development. It is one thing to get life started. It is another to get smart life started (life that can type up stuff about life!). How long does it take? Is our development normal, fast, slow, a fluke? This is a tricky area for sure. But a model I suggest (based on the modes of selection) says that when life is pushed it sinks or swims. When it is not pushed it floats along as is. That means that the most advanced and smartest aliens were those that successfully faced the most hardships - more selection of varieties that way. That is a tricky factor to determine - but it is a key one too. But, and here's another but..., this applies to Darwinian natural selection. Us humans also have cultural selection where we transfer culture/information from generation to generation. Once this begins all Darwinian rules are out. So for us in the future or aliens from out there, this is a factor that is a total unpredictable unknown. No one knows what cultural selection can do. That's a real 'X' factor about life anywhere!
4. All life is energy moderators. See essay on my hypothesis of how life began.
Note - if all life is 4 options of energy moderation - then this basic knowledge will be known by any advanced civilization. That also means they know how to resolve repressed conflicts connected with the 4 options. That in turn means they have eliminated repressed, mostly male, rage. Thus they will not be warlike and will come in peace.
5. Life has a speed limit! Sure it would be fun to whiz through space at light years per second. But it ain't going to happen. Matter (what we are made of) can't go faster than the speed of light. And stars are so vastly SPACED apart that it is hard to visit anywhere in a person's lifetime! Analogy - imagine two distances very, very far apart. Now take this times a million - and you have some idea of how vast the distances between stars - are. So it is more likely that aliens will not visit, (nor we them) but they might call! All in all life might exist outside the basic rules in this essay, but it is doubtful that it would proliferate.
On to Part II, What is Life?