Speculations on alien biology, communication, linguistics, psychology, society, technology, and theology, and the possible effects of contact or discovery of alien life.
In the Pleiades (known as Subaru in Japanese - yes, the car company is named for it), astronomers have discovered evidence of terrestrial planets forming, or having recently formed, around two young (100 - 400 million years old) stars in the Pleiades cluster.
"This is the first clear evidence for planet formation in the Pleiades, and the results we are presenting may well be the first observational evidence that terrestrial planets like those in our solar system are quite common," said Joseph Rhee, a UCLA postdoctoral scholar in astronomy and lead author of the research (UCLA, par. 3).
The Pleiades is a young open cluster 400 light years away. Some scientists feel that our Sun was formed in an open cluster as well; stars in an open cluster tend to wander from the "nest" as they age. So, we may see the beginnings of home worlds for future Subaruians (Pleiadians?).
UCLA News Results. "Planets found forming in Pleiades star cluster." SpaceFlight Now. 15 November 2007. 22 December 2007. <http://spaceflightnow.com/news/n0711/15pleiades/>
During this time of year, my thoughts turn philosophically, sentimentally deeper toward several things: family, the past, spirituality and, of course, life on other planets.
For family, this time of year means additional sentimental thoughts partly because, for the Northern hemisphere, the weather is growing colder, and the nights darker and longer, and so our hearts instinctively look to shorten the distances between loved ones to increase warmth, security, and hope.
For the past, at this time of year, with the New Year approaching, it is a time that we begin to realize that another year has gone, and we begin to look back and take stock of what has happened - sometimes with happiness, sometimes with new knowledge realized, sometimes with anger, sometimes with regret, and sometimes with sadness. If used right, it is a time of extra growth.
For spirituality, this season has strong, and many times somewhat similar, religious meanings for many of the world's theologies. This is in large part because, again for the Northern hemisphere, the Winter solstice brings not only the longest night of the year, but the knowledge that the days will now begin to lengthen again - the Sun returns, and with it renewed warmth and energy filled life. It is the promise of Spring. It is the promise of rebirth, renewal, and resurrection that we rejoice in and are thankful for. It is the promise of death conquered. And connected with looking back to the year that was, and looking close to loved ones, it is a time of year to be thankful yet again for the blessings that loved ones, that love, brings (though for those struggling with a bad year, with abandonment, it can be a very dark time of year indeed).
Of course, too often all of this is ruined by crass commercialism, by the pressures and stresses of false and shallow meanings that have been attached to the season. But that is a topic for other blogs.
For life on other planets, I wonder how they would treat a solstice on their planet? To be high level sentient does one have to be a pattern seeker, to look for the meaning and/or reasons for the patterns? If so, then such sentient beings would see the pattern of solstice and equinox as even our distant ancestors did (from even before Stonehenge) and work to apply a meaning or reason to the pattern (for to find meaning or reason is to find purpose and to be able to make predictions, and maybe even gain some control over - or at least the illusion/delusion of some control).
This, of course, depends on many factors which would affect the severity, or the placidness, of annual weather patterns. Is the planet in a very circular orbit, or a somewhat elliptical one? Is the planet close to its star, and thus with a very short year? Is the planet actually a large habitable moon circling a gas giant? Is there a virtually non-existent tilt to its axis or it is a large tilt? And what of these combined?
If, for instance, the planet is in a very circular orbit, at a close orbit (a red dwarf, for instance, would have a habitable zone much closer to it than a normal G-type star like our own Sun), and with virtually no tilt to its axis, such a planet may have very little differences between its seasons - and seasons that come and go quickly (smaller orbit means, usually, a shorter year). If a longest night is very quickly followed by a longest day (weeks later, i.e.), would there be as much imperative to celebrate the return of the sun's dominance in the sky?
For a planet-moon circling a gas giant, the sun could disappear for days at a time before returning to a "regular" schedule.
Or if the planet-moon is phase locked with its parent gas giant planet, then for the time it is behind the planet there would be, for the far side of the planet-moon there would be constant darkness until the planet-moon came out from behind the gas giant; but then the sun would rise and stay in the sky as it slowly arcs to the opposite horizon as the planet-moon orbits in front of the gas giant. On such a world, a short winter may cover the entire globe while in the shadow of the gas giant, and summer cover the entire globe while in front of the gas giant with extremely short springs and fall at the point the planet-moon is over the terminator line of the gas giant (the line where day and night on the gas giant meet, where one begins and the other ends). Maybe the world's sentient race would view their world as more of a unity than we view our own as on Earth the Northern and Southern hemispheres experience direct opposite seasons at the same time, while on this hypothetical world, both hemispheres experience the same season at the same time.
Anyway, back to the long day and long night, a primitive sentient mind may see that as a mighty heroic epic struggle between day and night. Though if a non-aggressive sentient species, say a slow moving herbivore species on a cool planet, maybe the day and night would represent a sort of "wheel of fortune" - first good luck (sun, warmth, plants taking full advantage) and then bad luck (days long darkness, worsening cold, plants folding up waiting for the sun)?
Additionally, there would be no solstice like we have - there would be no gradual shortening of the night - just one long night, and then one long day, each individual night as long as the night before, separated by an equally long day. Essentially, they would be in eternal equinox. Spring would be morning, summer would be the day, fall would be the evening, and winter would be the night - if you wanted to give them seasons. It may be more accurate to say such a world would have no real seasons at all, only the kind of "seasons" any day-night cycle would have.
If, instead, the planet-moon did have a noticeable tilt to its axis, and a non-circular orbit around its parent gas giant planet, which itself had a non-circular orbit around the central sun, or if the parent planet had a noticeable tilt to its axis with the planet-moon orbiting directly over the parent planet's equator, then the planet-moon, while still retaining non-changing lengths to its day and nights, would gain true seasons. The sun would arc over the sky differently through out the parent planet's year - while the planet-moon's year is the time it takes to orbit around the gas giant, the gas giant has its own year as it orbits its sun.
On such a world, a season would not be different parts of the planet-moon's year, but would be seen year to year. A number of years would be Spring, while another number of years would be Summer, and so forth, repeating itself. What a different kind of zodiac such a world would have! In some ways, it would be similar to a Chinese zodiac calendar (the year of the horse, the year of the dog, etc), except each zodiac would cover a span of years. Their zodiac could contain a zodiac within a zodiac within a zodiac.
Solstice on such a world may not represent so much the return of day, since it is possible that the day and nights would not change in length from year to year, but could represent the point where Winter is half over and thus the return of Spring begins. And maybe, just maybe, the celebration would be a whole year (for the planet-moon).
Of course, this is supposing that all higher level sentient beings feel, in an emotive sense, for in some ways spirituality, and especially sentimentality, depends upon emotion more (at least at times) than reason. Is emotion necessary to higher level of sentience? It seems on Earth, at least, the higher the level of sentience, the more emotion the creature seems to have.
Comments? Feel free to comment on any post in this blog. Please feel free to disagree with me (just do so respectfully please - even if you think I sin in any or all of my opinions, please recall, if you are Christian, Jesus' attitude toward the adulteress: while he was against what she did, he did not condemn her, and turned away those who would stone her).
Happy Holidays to you and yours (and even to Lrrr, Ruler of Omicron Persei 8, and his wife Nd-Nd. And what the heck, to Robot Santa too!*).
* If Lrrr, Nd-Nd, and Robot Santa mean nothing to you, you need to run, not walk, to the TV and catch an episode of Futurama.
From a 11 December 2007 press release from the NASA/ESA Hubble Space Telescope reported by SpaceRef.com
A team of astronomers have used the NASA/ESA Hubble Space Telescope to detect, for the first time, strong evidence of hazes in the atmosphere of a planet orbiting a distant star. The discovery comes after extensive observations made recently with Hubble's Advanced Camera for Surveys (ACS).
The team, led by Frederic Pont from the Geneva University Observatory in Switzerland, used Hubble's ACS to make the first detection of hazes in the atmosphere of the giant planet. "One of the long-term goals of studying extrasolar planets is to measure the atmosphere of an Earth-like planet, this present result is a step in this direction" says Pont. "HD 189733b is the first extrasolar planet for which we are piecing together a complete idea of what it really looks like."
The exciting aspect of this is, of course, the increased possibility that astronomers may, within years, measure the atmosphere of a planet that bears life - and life will leave its mark on any atmosphere. While not cold, hard, definitive proof of life (even then, some folk would just refuse to accept), it would be exciting evidence.
Alien Safari, from NASA's JPL can help you "Discover some of the most extreme organisms on our planet, and find out what they are telling astrobiologists about the search for life beyond Earth" (Alien Safari, par. 1).
The Safari includes the weird methane-ice worms found deep 80 miles off the coast of Louisiana. Life finds a way yet again! Though, to be fair, this doesn't necessarily mean that life can originate everywhere, just that life, once established, is tenacious and difficult to get rid of (you can, unfortunately, eliminate individual species easily, but getting rid of life entirely is extremely difficult). So it may bode well for terraformers more than for those searching for alien life. However, I still bet on life being rather common in solar systems.
More than 260 planets have already been discovered orbiting other stars, and new ones are found almost every month. Having trouble keeping track? Help is on the way.
Desktop planet counter: Install this widget for your PC or Mac and keep up with the current tally of newly-discovered planets.
Map of planet hunters: Interactive global view of scientists and techniques involved in searching for another Earth.
JPL is part of NASA's ongoing program of searching for planets around other stars, particularly those that might be Earthlike and potentially hospitable to life.
Yet more evidence suggests that a moon like ours is rare. Oh, moons are found aplenty around planets, but they tend to be rather small in comparison to the planet they orbit, and most of them are captured. Our Moon, however, was not captured, and is very large in comparison to the Earth. The ratio of the difference in size is so small that some astronomers propose calling the Earth-Moon system a double planet system.
Around 4.5 billion years ago, a large Mars-sized planet collided with the Earth in such away that part of the Earth's mantle was thrown into space. The Mars-sized impactor was absorbed by the Earth, it's iron core joining the Earth's. It also increased the Earth's spin. Most of the section of mantle that was thrown into space coalesced quickly into the Moon (may have taken as little as a year). The rest of the debris that was "kicked up" by the collision, and which did not coalesced, continued to circle the sun for millions of years before gravity and solar radiation cleaned it up.
Well, as reported before in this blog (Astronomers Say Moons Like Ours Are Uncommon - How Important is That?), some scientists feel that the Moon was essential to the origin of life on the Earth due to the tidal mixing which helped to mix, mainly from erosion caused by the tides, chemicals from the soil with the oceans, creating the chemical soup from which life arose. This is especially true for the young Earth when the Moon was closer and had a much more dramatic effect on the tides. Only 1/3 of the today's tidal effects is attributed to the Sun, the rest to our Moon.
In the original report, it was stated that maybe only 5 to 10% of planets would a moon like Earth's. However, a new report by Nadya Gorlova of the University of Florida in the November 2007 issue of The Astrophysical Journal, states that the percentage may even be smaller: 1 in 400. As reported by Physics News:
Using the cryogenically-cooled infrared orbiting Spitzer Space Telescope, Gorlova and her colleagues surveyed the 30-million-year old star cluster NGC 2547. They selected this cluster because of its age. The planetary building process usually ends by approximately 50 million years, making the odds of a giant impact unlikely to occur outside this window. The other advantage of NGC 2547 is that it is old enough for the material left out from the original cloud of
which solar systems formed to dissipate (this takes about 3-10 million years). By focusing on radiation at a wavelength of about 8 microns, they could detect the heat they would expect from dust at a distance of about one astronomical unit (1 AU) from a solar-type star. The NGC 2547 cluster was previously surveyed spectroscopically, so they could cross-check to make sure that the emission they detected was not due to gas (which would be evident by spectral emission lines). Out of about 400 stars in the NGC 2547 cluster, they found only one that showed evidence of dust from a massive impact.
What needs to be kept in mind are 1) this is just one sampling. There may be other factors at play here that, for instance, may have sped up the cleaning of debris after the collision, or otherwise minimized the debris; 2) statistically, an average is not found everywhere - that is, if 1 out of 10 planets, on average, form a Moon like Earth's, you would find some regions where the percentage was higher, and some regions where it was lower; 3) even without the Moon, enough mixing may still occur for life to begin (albeit maybe would've taken longer); and 4) there may be other situations such as a habitable moon orbiting a gas giant - where the tidal effects from the gas giant would be strong enough to mix chemicals on the young terrestrial moon.
Some planets may very well be true water worlds - totally covered in water. Though some, like Gliese 581 C (a "super-earth" 50% larger than the Earth 20.5 light-years away) may have dense water - maybe a thin layer of liquid water on top of compressed water. What sort of life would arise there? Think about it - no dry land, or extremely rare dry land that is easily flooded by storms or tides. Life transitioning to land would not happen, at least not large roaming life which needs territory to grow and thrive on (digression: could high level stationary sentient life ever evolve, I wonder?).
On Earth, life developed limbs and walked out of the seas - large tracts of land allowed for evolution to proceed in that direction. On a planet covered with one giant ocean, that direction would be blocked, unless the poles were cold enough to keep up the continued production of ice floes - then there could be an evolutionary path for living on ice floes part or full-time. Otherwise, any evolutionary development of limbs would go in the direction of underwater ambulation. But how useful is underwater ambulation? As useful as fins on land? And so, over millenia, higher sentient life would evolve totally adapted to the oceans. I don't think they would have just fins - hard to build and use tools without some means of griping and manipulating the physical environment.
That is not to say intelligent life needs a means to physically manipulate the environment, but that the ability to manipulate the environment does allow for greater evolution and progress of the brain, or at least to make it much easier for it to happen.
Maybe on some water world planet, a species of sentient life has evolved that can not manipulate the environment, but they have survived for millenia and so have slowly evolved to be able to do high order abstract thinking - their art, culture, science, and theology would all be based on communication - their only tool left to them; they would manipulate the mental environment. Art would be, for those that communicate via sound, vocal music and oral literature. Science would be based largely on observation and mental experiments (of the kind that Einstein made famous, but that the Greeks did to an extent as well) since they could do little experimenting (some, probably, but not much). They would not less likely to physically explore space, as they would not be able to leave their planet (water is extremely heavy, especially compared to air, lifting a craft full of water out into space would be extremely difficult -albeit not impossible - to do. In addition, making space suits for exploration, especially that of dry surfaces, would be extremely problematic as well). Would they be more likely to become telepathic then? To astrally project themselves? Or is that too "newagey?"
For a large planet with several times greater gravity, a thick ocean may have "normal" water at the top, but definitely, for a thick ocean, water that would become denser quickly the deeper one went - water become plastic, or even solid. We have a slight inkling of that here on Earth - mountain climbers know the air gets thinner as they climb, it is a danger if ignored. For our water world aliens, something similar may be in play.
Depending upon their evolutionary track, if they evolved as deep sea creatures, rising up to the surface may be dangerous - especially if they can not work with tools to create devices to help them breath or deal with the pressure change. Even sea creatures on Earth have ranges - some that live closer to the surface can dive rather deep, but they don't live in the depths. Other deep living creatures tend to stay in the depths, only coming near or to the surface when they are sick or dying (like giant squid) - near the surface is not a friendly environment for them to linger in.
Another thought - would, after millenia, creatures evolve to be like our flying fish? Would the air be conquered there as it has long been here as well by flying creatures? They would have to be creatures that feel at home surrounded by oceans, who do not need land to survive. Probably most likely flying fish like creatures, though maybe one some planets, the flying fish make the evolutionary steps toward fish that fly more than they are fish, and develop lungs and end up spending their lives either floating on the surface (when resting, for instance) and flying.
There are some sea birds on Earth that can live far out at sea, and may spend much of their life out at sea. Such birds tend to glide or soar more than the powered flight. This is because they can take advantage of the wind deflected by waves, and or by ground effect which reduces drag.
Because of convergent evolution (where unrelated species tend to develop similar characteristics due to their sharing similar environments, and due to the fact that the same physical laws apply to all species in the same environment) we can make educated guesses that creatures on other planets will tend to try to be efficient in adapting to their environments just like Earth life. If deflected wind and the ground effect is still in effect on this alien water world, then flying creatures there will glide more than they would use powered flight since the latter uses more energy.
Would these fully pelagic sea bird like creatures be the ones to most likely to become tool makers? They would have, possibly, develop feet (webbed most likely), which could have an opposable digit to help them grip prey (like modern Earth birds) and which could eventually evolve to manipulate tools (as a previous blog entry has noted, some birds, crows most notably, are known to create and use tools, and may be as smart, or even smarter, than a chimpanzee).
Or would the creatures be more like flying fish, or half-bird/half-fish - able to live under water (maybe to nest and breed) as well as live on the water surface and fly over it (to more easily hunt for food - flying through air is faster than flying through water - less dense, less drag).
Though one drawback (to sentient beings) is that on a water planet it would be hard to work with metals - to melt, smelt, and other wise work with metal to create structures and devices that would allow them to eventually explore the stars. Mining ore would be more problematic as well. Water is heavier than air, more dense - it takes more energy to move through it, and probably more difficult to shore up tunnels (not only would they have the weight of the stone above, but the pressure of the water on top bearing down). Light has a harder time penetrating water than it does gaseous atmospheres (sound, however, could travel great distances under water). Working with electricity would be harder. Building telescopes to view the heavens would be harder (though maybe on a planet with rare land, a species that could tolerate the air for short periods could build telescopes on such land - or the avian species, which would have a higher ability to tolerate the air).
On a larger planet, covered with water, how would that affect territorial issues? Would such creatures tend to be more nomadic - especially if they never develop the ability to farm, there is no need to settle down and build cities. Are cities necessary for advancement? Do cities help speed up advancement of civilization, and if they do help (which it does seem like they did for humans), are they the only way? Could nomadic species find their own way to help quickly spur on advancements in civilization? Without natural barriers like mountains, oceans, ice fields, deserts, and large rivers are to humans, would their be less isolation between groups and thus a more "we are one" sort of sentiment develop? Or would groups still develop, some adapting to more colder regions, for instance? (but would this still, in the end, create fewer insulated, insular groups than is the case on Earth?) Would this create a species that would be less xenophobic?
What theology would exist for such creatures? For those on planets with rare land - would the inhospitable land be their version of hell? Or for deep dwelling sentient species, which can not bear being near the lower pressure regions in the upper regions of the sea, would the upper, more lighted, and more dynamic regions be more like hell and heaven more like the darker, heavier, and calmer pressured regions? Would they think all planets are ocean, and that heaven would be a calm ocean? They probably would have some tectonic activity - underwater volcanoes - as well as deep, dark trenches that could play roles in primitive theologies. And for the water bird sentient species, how would their primitive ancestors first think of the world, theologically (I suppose they would love the O.T. verses that describe God as a mother hen).
1. Would a water world be less susceptible to extinction level events from meteor impacts (no dust to throw up into the air to create a long lasting year round winter that kills off the plant life, no cracking open part of the crust and letting out lava, etc)?
2. There is an article in DVICE.com about the Focus 21 France, a hovercraft prototype that would use the ground effect to achieve helicopter speeds. It would have to fly close to the water to take advantage of the ground effect (a height equal to twice the wingspan or less). I thought that maybe that is how water world sentient species would fly, at least for their earlier flights. Sort of like sub-orbital or low earth orbits for us.
White, Charlie. "Focus 21 France uses ground effect to zip above the waves" DVICE.com. 3 December 2007. 9 December 2007. <http://dvice.com/archives/2007/12/focus_21_france.php>
Astrobiology Magazine has a neat (OK, neat for space geeks) online interactive program that allows you to "Build a Virtual World" by playing around with many different environmental factors, from reflected sunlight (albedo) to the amount of methane in the atmosphere - it then tells you how much of Mars would be habitable under the conditions you set.
In three previous posts, "Planets, Planets Everywhere," "Young Sun-like Star Already Parent," as well as The Introduction to this blog, we learn that planets seem rather common-place: they form readily. All you need is debris or dust circling a star, gravity, and time (a million to several million years). Planets even are reborn around pulsars - regenerated from the blasted debris of the star's original planets (planets destroyed by the enormous supernova explosion that preceded the star becoming a pulsar).
And this got me to thinking - how come the rocky and dusty debris of the asteroid belt has never coalesced into a planet or dwarf planet? Possibly the tidal influence of Jupiter? If anyone has any input on this matter, it would be gratefully received.
The Spitzer Space Telescope has discovered a young Sun-like star, UX Tau A, may already be a parent, even though it is only 1 million years old! Within the thick dust disk surrounding the star is a gap - a gap indicative of the sweeping action of a planet (or planets); planets that form out of primordial dust disks tend to clear a path through the disk. A process called photoevaporation can also clear away some of the disk from the star outward some distance, but since there is a thick ring of dust close to the star, then the gap, then another thick ring of dust - photoevaporation cannot be the cause.
If this is the case, then it is yet more evidence that stars and planets are a common combo, like peanut butter and jam, ham and eggs, or like Homer and doughnuts.
Jet Propulsion Laboratory. "Youthful Star Sprouts Planets Early." SpaceRef. 29 November 2007. 2 December 2007. <http://www.spaceref.com/news/viewpr.nl.html?pid=24132>
In 2003, NASA, through the input of more than 200 scientists and technicians, finalized an Astrobiology Roadmap to outline and prioritize research and exploration pathways. The Roadmap has six goals:
Goal 4: Understand how past life on Earth interacted with its changing planetary and Solar System environment
I will be returning to this topic from time to time, especially Goal 3, which actually speaks of developing a study of universal biology.
Reports in The Ecologist and National Geographic reports that crows are carrying walnuts in their beaks to intersections, wait for the traffic light to turn red, drop the walnuts and after the cars run over the nuts, fly down and pick out the walnut meat. The National Geographic continues, stating that crows can make tools - and not just by accident. They create two different tools, depending upon the need. Apparently crows are as smart as chimpanzees, and studies seem to show that actually, crows are better at making tools than chimpanzees.
In addition, studies show dogs can map language. Great apes have been taught to communicate using sign language. We know that some animals can lie (recall, for instance, the article "Lemurs can be liars, if they think you want their food" in the May 2006 issue of Monitor on Psychology).
So, if planets are a natural consequence of the laws of physics (especially gravity) given a debris field, and life a natural consequence of the laws of physics and chemistry given liquid water, common basic organic molecules (found everywhere in space, from nebulae to comets), and an energy source, is sentient life a consequence of the laws of biology given a "boring" enough environment (see "Universal Biologies - Order from Chaos," and "Sentient Life" post)?
This is not to say that the universe is teeming with sentient life. While life is probably fairly common, most of it will be microbial type. Even with Earth's history, microbes account for most of the timeline for life. While catastrophic events can (and have, on the Earth) wipe out larger life forms, microbial forms are the most likely to survive.
Microbes can even survive being blasted into space; for example, if a large meteor hits a planet, large chunks of the planet can be launched into space. If one of those chunks hits another planet - life may be seeded there. Some feel that maybe that has happened between Mars and the Earth: some say life may have started on Mars first, then spread to the Earth (making Mars the garden of eden, and it did have a much wetter and warmer past), others say the reverse.
In addition, some environments are probably too harsh for large, complex life forms to evolve, or greatly slow down the evolutionary process (increasing the chances for a large enough catastrophe to set the evolutionary clock back).
But, life will find a way, and where there is life, there is hope. Thus, I believe sentient life is a natural potential - it will result if given a chance. But it won't be as common as, well, "common," or lower, life forms.
Dingfelder, S. "Lemurs can be liars, if they think you want their food." Monitor on Psychology. Vol 37, No. 5 (May 2006). 10. Can also be found at <http://www.apa.org/monitor/may06/lemurs.html> (as of 1 December 2007).
Watching the "Alien Planets" episode of the History Channel's Universe program, we learn an interesting discovery: planets around a pulsar (for example PSR B1257+12). That should be impossible - a pulsar is what is formed after a massive supernova explosion, an explosion so powerful that any planets should be destroyed. However, three small rocky planets were found. What they now hypothesize is that these are planets that formed from the debris of the destroyed orignial planets. If this is so, then this is more proof that planets can form even under extreme conditions; gravity wants to clump debris together, it is a natural consequence of matter and gravity. Thus, planets are probably very, very common.
By the way, life on a planet around a pulsar is very unlikely - there is far too much radiation flooding the system, especially if the planet happens to be in the way of the emission beams from the pulsar's magnetic poles.
Pennsylvania State University. "Scientists announce smallest extra-solar planet yet discovered." 10 February 2005. 29 November 2007. <http://live.psu.edu/story/10180>
Some more contemplations on color and culture. Color can be useful for helping to distinguish between unripe, ripe, and overripe fruit; threaten or warn; distinguish between types of prey (which kind of beetle is tastier); and attracting mates; to mention but a few uses, and thus reasons for, the ability to see in many colors. For creatures who can see in color and find it useful, and who develop advanced sentience (including the ability to think in abstract terms), there is a probability that they will assign metaphorical meanings to color as well.
Some of this was mentioned in the Color of Life post; think of what various colors mean to us: yellow means warmth, light, day, energy - it is a positive color; red is connected to blood, and often means life, and from spilled blood, sacrifice or death; blue is a color of coolness, water, and sky; black is the color of night, mystery, and death, and of course green is for food, sustenance, fertility, serenity, and life.
Around different stars, these colors could easily take on other meanings. Around a hot blue star, blue may not be a color of coolness. The sky may very well be blue, with a brighter blue spot for the sun - which could be interesting. Think about what if our sky was yellow? Our yellow sun would be this bright part of the yellow sky, a bright spot that moved. Maybe we wouldn't be able to tell exactly the boundaries of the sun and so not, at first, recognize it as a self contained body circling the Earth, but instead just a brightness that moves across the sky.
So too, possibly, for some planets circling a blue star (a B class star - O class stars are also blue, but being the most massive stars in the universe, nd can not form planets due to the photoevaporation effect). Blue stars tend to be extremely hot and bright - the star would be this large very bright blue spot in the sky, the sky being a gradient from somewhat darker blue at the horizon, moving to lighter and brighter blue at the center of the bright day light. The world would be bathed in blue. Plants could be fuchsia, or even purple, in color. Oceans would have fuchsia or purple algae like plants in it, giving the seas there a violet or purple tint.
It is possible that some planets around F-stars would be home to plants with blue and blue related hues. Creatures trying to conceal themselves would develop blue skin colorations (Andorians?). That could either elevate blue to some mythic status, or because it is so common, other, more rare, colors would hold greater value.
Another possible result may be that some creatures, especially the carnivores, may find being color blind an advantage - with everything awash in blue, the ability to detect differences in brightness and texture would become more important than color itself (see the post Color Blindness Advantages - What Drives Color Range? for more information). Maybe blues would be seen in grayscale, while the other, more rare, colors are seen as they are. To such beings, the day time sky would appear a bright light grey, with the night sky black - and as the day turns to night, the sky changes in a sliding gradient from very light grey to ever darkening grey, and finally to black.
On a planet with black plants (possibly on a planet circling a dim, red class M star, the most common star in the universe), black could come to represent life (literally to the primitive sentient mind and metaphorically to the advanced sentient mind) - the opposite of how many Earthlings view the color. And if black was food, sustenance, fertility, and thus life - then what of the black night sky? Think of how such a planet would look to human explorers - say a somewhat dim red sun in the sky (giving the appearance of constant approaching evening), in a crimson, fuchsia or magenta sky (*), bathing black plants with reddish light - what a demonic place it would appear to human eyes, a Dante planet. Yet, to the natives, those would be the colors that would bring peace, and calmness - it would be the colors of home. Red would mean life, as well as black. The night sky would be as important, color-wise, as the day sky. Space would always have this connection to plants, to food, to sustenance - even if subconsciously. So maybe such creatures would be less fearful of space - they would find a comfort being surrounded by the blackness like some people on Earth feel when in a heavily forested mountain, or dense tropical jungle - surrounded by the color of life.
Would primitive aliens on such a planet think of the night sky as being a large plant leaf that blocks the sun (but, like all leaves, has imperfections, imperfections that allow some light to sneak through - star light)? One of their gods could then be a plant god. And since plants need the sun, this is not an evil god, just one that is taking its turn soaking up some sun. Or maybe it is an evil plant-god (some plants are poisonous, after all) fighting with the planet's creatures for the life-giving rays of the sun, a battle that occurs every day-night cycle (ancient humans thought somewhat similar battles went on between the Sun and the Moon - brought to terrifying climax with solar eclipses, which gave the appearance of the Moon eating the Sun, and to which primitive humans tried to help the Sun by banging on drums or shooting arrows in the air at the Moon to drive the Moon away - which of course always worked!)
* Depending upon how much blue light the star also radiates, and how much ozone is in the atmosphere to scatter that blue light- while an M-star radiates red most strongly in the visual range, it doesn't mean it does not radiate any other color.
Most members of the animal kingdom can regenerate lost body parts at some (or all) of their life cycle. Mammals aren't one of those animals. Yet, scientists say the pathway (called the Wnt pathway) still exists, untapped, in mammalians.
Before we start speculating on alien sentient beings being able to routinely sprout new appendages (or like Jeebs, the hapless alien in MIB I and II, a new head), the question that first needs to be pondered is why have mammalians lost, or suppressed, this ability. On the surface, it seems like it would be evolutionary advantageous to retain this ability. Yet apparently it was also advantageous to lose it. Even among creatures that can regenerate, many of them can not do so when adults. This seems to indicate that there must be some problems with regeneration, especially with advanced life forms.
It is obvious we do not fully understand all the parameters regarding regeneration. However, the fact remains the Wnt pathway still exists, latently, but exists in at least some higher mammals. Thus, maybe it is not far-fetched to think there could be sentient aliens with at least some regenerative abilities. In addition, since Earth scientists are looking to restart this latent ability (and have had some success with adult frogs and chicken embryos), it is a distinct possibility that other alien sentient beings could work on restarting any latent regeneration they may have, and may be successful, either as medical procedure, or as a full time reacquired ability.
However, the more advanced the creature, the more there are limitations to the regeneration - that only makes sense. Simple structures are easier to rebuild, with less chance for mistakes. Not so for complex structures. Simple structures require less energy to rebuild than complex structures. Simple structures can rebuild faster. And finally, simple creatures tend to less centralized, the less centralized they are, the easier they can live without a part of themselves. Complex creatures tend to have rather centralized controls. Which brings us to an important point: there are structures that just can't be regenerated - such as a heart, or brain. How can a mammalian body naturally survive a missing heart even if it has the ability to regenerate? The body cannot survive long enough without a heart to give time enough for another heart to regenerate. Same with a brain - if the entire brain is dead or missing, the body cannot continue functioning long enough to allow for regeneration to complete (and even if a creature could regenerate a new head, ala Jeebs in MIB, how could it retain all its knowledge and memories?).
So, how would this affect culture, if we could routinely regenerate missing ears, noses, arms, or legs? For one, it would prolong life - for instance, amputations due to illness would be a temporary set back as the body regrows a healthy new appendage. Maybe more people would be greater risk takers, since the risk of death or permanent dismemberment or disfigurement is lowered (cosmetic surgery? Just remove the offending area, and let a new area grow back). But it also may make war or violence even more common place, since soldiers could be more easily resent back into battle (wars of attrition would take much longer). Of course repeated violence, repeated being torn apart and regrowing must have an affect on the brain, especially on the mental "adaptation" to such a "life." This would also affect culture.
The tougher question is how would it affect theology? What kind of theology would an alien race that had strong natural regenerative powers have?
ScienceDaily (2007-11-22) -- The next time you take a moonlit stroll, or admire a full, bright-white moon looming in the night sky, you might count yourself lucky. New observations suggest that moons like Earth's -- that formed out of tremendous collisions -- are uncommon in the universe, arising at most in only five to ten percent of planetary systems.
Though 5 to 10 percent of billions of planets is still a large number of planets with large moons (the size of the Moon is so large in comparison with the Earth, it leads some to speak of the Earth and the Moon as a Earth-Moon system, or a double planet).
However, this is an important issue when discussing, speculating, on alternative extrasolar biological, psychological, theological and societal realities that could exist.
Firstly, how important is a large moon to the rise of, and sustainability of, life on a planet? Some say the moon, by its size, helps protect the Earth from large meteor bombardment. That is debatable. One could actually argue that the Earth protects the Moon more than the Moon protects the Earth since the Earth is larger than the Moon, and hence a bigger target and a larger "attractant" due to its larger gravity. Also, one could also argue that the Moon also increases the chances of meteors coming close, by adding its gravitational pull (think of the Earth and Moon as one system: add up the gravitational attraction it would have on passing meteors). Additionally, while the Moon is large, it is separated by 250,000 miles. The further away you hold a large shield from you, the less of a shield it becomes. When a meteor heads towards the Earth, the Moon would have to be pretty much in the direct path. Remember, the gravity pull of the Earth is several times larger than the Moon's - in a tug a war between the Earth and the Moon over a meteor, I would lay bets on the Earth "winning."
So while the Moon may give the Earth some protection, it may not give us as much as we think. But, it may have been enough. Let us say that without the Moon's protection, we would've experienced only one additional large meteor impact over the history of the planet to date. That one additional impact would easily change the course of sentient development on Earth - most likely delaying it by millions of years. And quite possibly changing the final face of the sentient creature that did eventually evolve.
Secondly, the size of the Moon does help keep the Earth from being too wobbly on its axis. This helps keep the seasons from being overly dramatic, which would make it more difficult for complex life to arise (though, I would argue, not impossible, but probably would prolong its rise, and thus delay the rise of sentient life).
Thirdly, the Moon affects the tides on Earth. A smaller moon would have a much smaller effect, and without a moon, there would be an even small effect (the Sun would have an effect, but only 1/3 of the effect the Moon presently has). The tides have profound effects on the Earth - mainly from erosion which helps mix chemicals, especially for the young Earth (when the Moon was closer and had a much more dramatic effect on the tides).
By the way, did you know that this tidal affect is also responsible for pushing the Moon slowly away from us? The Earth is rotating faster (essentially 29 times faster) than the Moon orbits around it. This causes the high tide to move ahead of the Moon. Recall that a high tide is a bulge in the oceans of the Earth facing the Moon (and directly opposite of it). This bulge has mass, and thus gravity; this added gravity tugs on the Moon - but since it is slightly ahead of the Moon (due to the Earth rotating faster than the Moon orbits) - this tiny gravitational tug pulls on the Moon, accelerating it. The result of this constant tug is that the Moon is slowly accelerating, and thus spiraling away from the Earth. As time passes, the Moon will get further and further away (though as it gets further away, the Moon will have lesser effect on the tides, which will thus mean that the resulting acceleration would decrease - but not to zero, the Moon will continue to spiral away). So for those that remark at how miraculous it is that the Moon is the same apparent size in the sky as the Sun need to recall that it hasn't always been that way, nor will it stay that way (plus the Moon isn't exactly the same apparent size as the Sun - but it is very close to it).
Another result of the above is that the energy for the acceleration of the Moon comes at a cost to the Earth: it's angular momentum decreases. The result for this is a lengthening day. Some calculate that billions of years ago the Earth spun much faster, and without any moon, a full day today would be around 8 hours instead of 24. This faster spinning Earth could also have much stronger winds as well. Life would look a bit different on a planet that had stronger winds, a shorter day, and smaller (but more frequent) tides.
Not having a moon would definitely have affects on the culture and theology of a sentient race. Think of how strongly our Moon plays into many of our primitive theologies and myths. But another consideration is how the dark skies would affect the alien race as well: darker skies would mean more attention paid to the stars, but I think an even stronger effect is that having a large moon so close to us may have encouraged us as a species to think about exploring space sooner than we would've otherwise. Without a moon, there is nothing close enough to explore - for thousands of years, the planets were just thought of as wandering stars. The only other physical body was the moon. Without the Moon, it would be quite some time before we would realize there are other physical bodies besides the Earth. Without a moon, there would not be that stepping stone that we enjoy - going to the Moon is far easier than going to Mars. It gives us a chance to learn, experiment, and gain experience before heading off to more arduous and more difficult explorations.
One way a habitable planet may have some of the benefits of a large moon without having a moon orbiting it, is for the planet to be a large moon itself, and circling a gas giant. While that gas giant would surely attract more than its share of meteors, the orbiting moons are so very small compared to the parent planet, that most would probably miss the moons. Not all, of course, but no planet or moon is totally safe from meteors.
Let's say a planet about the size of the Earth was circling a planet the size of Jupiter. There would definitely be tides! And as we see with our own system, giant planets are like a solar system themselves: ringed by many captured moons. A habitable "moon" circling such a gas giant would have many near by physical neighbors to visit, explore, and colonize (or base stations on). Such a civilization may be more even encouraged to explore space than our own.
And what a god the gas giant would probably play in their primitive theologies! Would they look up in the sky filled, at times, completely by the gas giant, and think "is that heaven" or "is that hell?"
Actually, that may be a downside - orbiting such a large planet would mean periods where the sun would be blocked by the gas giant, and day and night would both be dark (with part of that darkness without even any nighttime stars). Though the times the moon was in front of the gas giant (between the planet and the sun), the night would be ruled by the reflected sunlight off of the planet's cloud tops. Life has adapted to life above the arctic and antarctic circles here on Earth, with their months long days and months long nights, so life could easily adapt to orbiting a gas giant - though the orbiting moons may well have such fast orbiting periods (for one thing, as big as Jupiter is, it is still much smaller than the sun) that these periods of full light and full darkness would be short - Io orbits Jupiter in under two days, while Europa orbits in under 4 days. Leda and Himalia have the longest orbiting periods for a Jovian moon: just over 238 days for Leda and 250 for Himalia. Nights (where the sun is totally blocked by Jupiter) on those moons are probably around one or two months long (haven't worked out the exact numbers; the distance from Jupiter is a factor - a theoretical moon with an orbit of 250 days at 600,000 Km from Jupiter would have a longer day long nights than another moon with the same orbit, but at 11,480,000 Km away. The shadow of a planet is not a cylinder, but a cone, it gets more narrow the further out it goes).
Another thing to consider is if the orbiting moon is in phase lock with the planet - the rotation period the same as its orbital period, thus ensuring one side always facing the planet it is orbiting. Our Moon is like this - we only see one side of the Moon from Earth. Those living on the far side of the orbiting moon would never see the gas giant (well, if they stayed near the equator. If they moved some distance north or south of the equator, they would begin to see the top, or bottom, of the gas giant over the horizon). They would have a long day, followed by a long night. Those on the near side would always face the gas giant. Most of their daylight would be the reflected light off the gas giant, though as the moon orbited the planet, those living on the near side would get short glimpses of the sun - it wouldn't rise high in the sky, however. And then they would experience a starless night (though for the same reason they would get a short glimpse of the sun before or after night, they would get a short glimpse of a star filled night sky after or before night).
It would be interesting to entertain what kind of mythologies would arise on the near side and on the far side of such a world. For the near side, a massive god before them, and a bright god that flirtatiously appears once during the short year, and a star filled sky half a year later. For the far side, the bright god of the day, but this looming god just over the horizon, peaking over. And then there's the many small moons whizzing by, some below, some above the world - what to make of them? Also, would such a world figure out sooner than we did that the universe doesn't orbit around the habited world?
Another downside to orbiting a gas giant could be the intense radiation belt surrounding the giant planet. Io, a moon of Jupiter, orbits closer to the Jupiter's cloud tops than the Moon orbits the Earth. Jupiter has massive radiation belts, and Io cuts through them, causing Io not only to be bathed in high levels of dangerous radiation, but creating huge currents of electricity that flow along Io's own magnetic field (bathing the moon in auroral glow).
Another downside is that such a "moon" would have greater tides. The closer it circles the gas giant, the greater the tidal forces. It is thought that the tidal energies experienced by the moons orbiting Jupiter and Saturn are keeping the cores of the moons heated. There is direct evidence of geological activity at work on many of the moons. For instance, it is thought that tidal forces are what are causing the volcanic activity on Io, and is one of the mechanisms thought to create liquid oceans under the frozen surface of Europa (also a moon of Jupiter).
ScienceDaily (2007-11-23) -- Scientists have discovered some unexpected forms of liquid crystals of ultrashort DNA molecules immersed in water, providing a new scenario for a key step in the emergence of life on Earth.
A key missing step in the process has been discovered - it is felt that the formation of full DNA molecules by random chemistry is essentially impossible, and thus scientists have been searching for more primitive and simpler molecules that would self organize. These, then, could lead to DNA.
This discovery of liquid crystal form of self organizing ultrashort DNA is an amazing discovery. Small repeating patterns combine to build larger repeating patterns which combine to build even larger and more complex patterns. Evolution works fairly quickly with simple organizations, and slows for more complex organizations, as we've seen in a previous post (Sentient Evolution ).
This helps support New York University chemist Robert Shapiro's earlier statement that life began from cyclical reactions involving small molecules: "these reactions would produce compounds that would feed back into the cycle, creating an ever-growing reaction network" (Schirber, Par. 13). The cyclic reactions from the small molecules would eventually create more complex molecules that would be more efficient, replacing the smaller molecules: "the system would learn to make slightly larger molecules" (Schirber, Par. 15). This is the "metabolism first" hypothesis of how life began (the other main thought is that RNA came first).
However life started, there is evidence it started 3.7 billion years ago, and fossilized bacteria found as old as 3.5 billion years. There is evidence that some form of photosynthesis began nearly at the beginning, if not at the beginning. This may indicate yet again that photosynthesis may be one of the more common energy sources for life, especially early life - may even be a common, almost universal, part of the rise of life; thus, the most common life form in the universe may well be simple plants. When the writer of Genesis says God created plant life first, and far before animal life, that writer was right - He didn't dally with the plants.
A short article in the October issue of Discover explains that sometimes being color blind isn't a bad thing. It was discovered that color-blind capauchins (a species of monkey native to S. America) were more successful at hunting camouflaged insects than capauchins with broader color vision. One hypothesis is that color-blindness actually helps improve the ability to notice differences in texture and brightness, thus being able to better detect camouflaged insects. As a hobby artist, I find that black and white photos sometimes show me more than a full color photo, especially in looking for differences in contrast or brightness - sometimes full color sends too many signals to the brain.
So, in addition to possible alien sentient beings able to perceive only or mainly in the UV range (see previous posts with the tag "alien senses"), or in the infrared, some aliens may see within our range, but be color-blind compared to the average human. Of course, we woul'd be UV-blind (though there have been rare instances of humans being able to see partially into the UV range).
Sex and food primarily, and possibly detection of enemies. For instance, some researchers feel that first color vision arose because those who evolved the ability to see color were better able to distinguish ripe fruit. As the primates developed, and then improved, their ability to see red and orange, the primates began to develop orange and red hues to their hair and skin (or maybe more accurately, those few primates that had orange or red hair stood out from the others and thus were favored by the primates that were more successful in finding ripe fruit).
Interestingly, humans can normally only keep track of three items at once, but if groups of items are of the same color, then we can keep track of three groups, or sets, of items, and thus keep track of many items at once - as long as the items are grouped in no more than three sets of colors (thus, one reason for team uniforms). Not sure what the benefit is of only three. Why not four or five? But at least our minds can use the "trick" of color to get around that limitation somewhat. Maybe humans hunted packs of animals in packs themselves, but also needed to keep track of their human pack leader (the "alpha wolf"). Thus, team uniforms are very advantageous for the spectator: with the two opposing teams in different colors, and the referees in yet a third color, the spectator can keep track of what is going on far better than if everyone wore whatever they wanted, with no player having the same color scheme as any other player on the field. Sports may not have been the evolutionary pressure to develop this ability to track three sets based on color, but instead an example of how the modern mind takes advantage of the situation.
But if we could answer the question, why three, we may be able to determine the conditions needed for an alien species to develop the ability to track four or five (or just two). The ability to track different items will affect the alien civilization's social, cultural, and theological realities; think about the three again: humans have trouble tracking more than three items at once, and three seems to be a holy number for many of our theologies - coincidence? Maybe for aliens that can track four items at a time with ease, four would be their common holy number. And maybe they would have games involving three teams at once.
American Institute of Physics. "Tracking Your Team." Science Daily. 1 December 2006. 25 November 2007. <http://www.sciencedaily.com/videos/2006/1202-tracking_your_team.htm>
It seems the more complex the sentient mind, the slower it evolves. Apparently this is because the genes in the complex mind code for proteins that have complex interaction with other molecules in the body: "change a gene too much and it will be unable to continue its existing functions" (Barone, Par. 2). Thus, the more a brain evolves, the slower its evolution becomes. Though some postulate that the recent information revolution, with its explosion of information and rapid technological change may add extra evolutionary pressure on our brains.
Anyway, this may be another reason why sentient life needs long "boring" (no planet-wide catastrophes) stretches of time to develop, and another reason for some to believe that while life itself may be fairly common in the universe, intelligent life may be somewhat (or even very) rare.
I disagree that it would necessarily be rare - hopefully, if a sentient species makes it to space travel, it will begin colonization and thereby increasing the likelihood of its survival as a species. Space colonization would have an evolutionary pressure on the beings - living in different gravity fields, electromagnetic fields, or atmospheric oxygen compositions for instance, may cause evolutionary changes. These changes wouldn't necessitate brain changes, but body adaptation changes (longer or shorter legs, larger lung capacities) which are not as complex changes to make as are changes in the brain.
Of course, that's skirting around the issue a bit - or cheating: a few sentient species spreading throughout the galaxy is not quite the same thing as sentience being a common result of habitable planets.
One result of this (as complexity of the brain increases, evolution of the brain slows) may be that the old, oft used Sci-Fi adage that advanced aliens would be to us as we are to ants may not hold as much water after all. Sure, a species that's been around for a billion years longer than we have, would have an evolutionary leg up on us, but to compare us to ants? Maybe a lemur would be a more appropriate comparison (by the way, there's an interesting article "Lemurs can be liars, if they think you want their food" in the May 2006 issue of Monitor on Psychology. Not so dumb, after all, these lemurs.). And how many billion year old civilizations would their be? And how many of them had continuously advancement (no dark ages, or no catastrophes that set them back)?
I've wondered sometimes if that would be another reason for extraterrestrials to come visit the Earth: a civilization that was a billion years old may very well have forgotten how they came to be - look at how just much we don't know just several thousands of years back in our own history. They may have great curiosity at how a primitive technological civilization begins. Think how intrigued we'd be if we found a planet of somewhat similar looking creatures were in their stone age era. We'd want to observe them, to maybe get some ideas to help us figure out our own past. Sure, there would be differences, but even the differences can teach us something. It is like studying the weather on Venus and Mars - both have extreme difference in weather, but the two planets are similar enough to Earth in other ways as to be very instructive; Venus and Mars are like two experiments that help us to set parameters, or to see certain forces more clearly on them that are also at work on Earth, but not as obviously.
Dingfelder, S. "Lemurs can be liars, if they think you want their food." Monitor on Psychology. Vol 37, No. 5 (May 2006). 10. Print. Can also be found at <http://www.apa.org/monitor/may06/lemurs.html> (as of 25 November 2007).
No, not talking about a cosmic Jack Lalane (OK, too old of a reference). At my first alma mater, the University of Tennessee, Knoxville, the physics department has a java applet online that demonstrates why hot stars look blue and cool ones look red using Planck's Law, Wien Law, and Steffan-Boltzmann Law. It calculates the blue-visual and ultraviolet-blue color index, as well as showing where the normalized intensity lies in the ultraviolet - visible - infrared spectrum. This site is found at: <http://csep10.phys.utk.edu/guidry/java/wien/wien.html>.
I found it interesting that as a star gets hotter, its normalized intensity peak lies increasingly in the UV (ultraviolet) range of the spectrum. As stars get cooler, the peak moves toward the infrared, but doesn't get into the infrared except for very cool stars.
This would mean that for hot stars, UV would be the more important wavelength to use, while for cool stars, infrared could have some importance. Our eyes are centered around the normalized peak for the sun, with it's 5,780 K surface temperature, which makes logical sense. For beings on a planet around a blue star, their eyes could be centered in the UV band. They may not even have much use at all for the "visible" part of the spectrum ("visible" to us).
For plants, I wonder if this would mean they would be white, since they'd be using the UV photons for photosynthesis instead of our visible light range they'd reflect back all of the visible (to us) light - thus they would appear white. However, it seems unlikely that UV light photons could conceivably be used for photosynthesis. UV light is very energetic, and thus, for the most part, very damaging to life: UV inhibits photosynthesis in present day Earth plants and it can cause destruction to DNA as well as many proteins and lipids. The shorter the wavelength, the more energetic and the more damaging. However, it is thought that UV was an important source of energy in the creation of life and some viruses, bacterium, and fungal spores are rather highly resistant to UV radiation. However, often times creatures that are highly resistant to UV radiation are resistant because they have developed a mechanism for repairing the damage done by the UV radiation, and not because they can just ignore it.
Thus, there are limits to what carbon-based plant life can tolerate with regards to UV radiation. And for a planet around a particularly hot blue star, life would definitely have to find a way to deal with the UV radiation (here's a thought: if UV is thought to be important to the origin of life, would that mean that life is more likely to originate around blue stars than for other stars?). There are two articles, "Limits of photosynthesis in extrasolar planetary systems for earth-like planets," by S. Frank et al. and "Ultraviolet radiation constraints around the circumstellar habitable zones," by Andrea P. Buccino, et al. which I hope to get my hands on soon. Part of the Habitable Zone equation may not only include the zone where water can be in a liquid state, but also where UV radiation isn't extreme.
Anyway, there are some creatures on Earth that, while using the visible spectrum, also use part of the UV spectrum for vision. Various insects, for instance, can see into the UV spectrum - and some flowers have patterns on their petals that can only be seen in UV light to help attract the insects (to aid in pollination).
What would this mean for alien life? That they may be blind to most, if not all, of our "visible" spectrum, and we to theirs. This is not to say they would be blind, rather they would just find an inside room lit with light bulbs to be rather dim if not completely dark: most fluorescent lamps are designed to give off minimal amount of UV radiation - much less than what could be found out of doors (the mercury vapor in a fluorescent lamp does give off UV radiation, but it then collides with the phosphorus coating on the inside of the bulb, and thus is "converted" into visible light). Some lamps, like LEDs, do not give off any UV radiation. LEDs would be invisible to a being who sees only in the UV range.
This isn't an either/or proposition, of course. Some beings could have eyes sensitive to a large range, with part of their visible spectrum in the UV and part in our visible spectrum. They would be essentially color-blind in that they would see some colors, but not all (for instance, can only see blue and green). Many animals on Earth have limited color range, seeing mainly black and white. Even some humans only see in black and white: more than 5% of the natives of the island Ingelap, in Micronesia, have the rare condition of Monochromasy - total color blindness (Oliver Sacks wrote a book about them, titled The Island of the Colorblind).
Not sure how this would affect the alien's culture or theology, though they would see the night sky differently than we do, seeing patterns that we do not see, which could affect their theology to some degree. It would definitely affect their visual art - painting, drawing, and video. They would work on UV cameras first, and create UV TVs - rather different technology than what we came up with (I wonder how a UV TV would work?). The biggest affect, I believe, would be in the contact between us and them.
Of course, some Sci-Fi movies do have aliens that can only see in infrared or UV, though usually just in infrared, as it makes for more exciting drama to have an alien that can see our body heat - making us stand out like glaring targets, while the alien is concealed to our vision. That would indeed play on our visceral fears, if we knew that our new alien friends can readily see in infrared.
In a recent edition of Discover, an article, "Aliens Among Us," asks the question "do we share our planet with alternative forms of life?" (62). Mathematical models indicate that there is a 95% chance that life originated two or more times on the Earth. There is no reason, from natural laws, that life didn't have more than one origin. DNA based life dominated, but that doesn't mean that niches are filled with RNA based life (DNA based life uses RNA, and evolved from RNA based life). At present, most of our methods for detecting life do not look for RNA, they look for DNA instead.
In early Earth history, the Earth would've been bombarded by large planetoids, comets and meteors - some of which may have wiped out early life. Life would've begun again. Why? Why can chemical reactions be predicted if the type and quantity of the chemicals involved are known as well as the environment (temperature, pressure, etc)? Why can large (and thus Newtonian) physical systems be predicted given known values (mass, density, magnetic fields, etc)? Because laws are universal. Given certain range of conditions, life will rise.
Life has great variety on Earth "but at the molecular level they are staggeringly uniform" (62). This doesn't mean that alien life will share the same uniformity as Earth life. But it will probably have its own uniformity. And it does mean that when looking for life, we need to broaden the tool set we use for looking for life. But it also means that here on Earth we need to study all the forms of life that exist here to help us gain an idea of the universal biology laws.
You see, forces all work to find an equilibrium. A star burns because gravity compresses it down, igniting a nuclear furnace. The radiation pressure from that furnace pushes back against the forces of gravity. While they balance, the star burns in an overall steady state. Depending upon mass, the star lives a long life, or a short life, and ends in a supernova or a blackhole (OK, this is a bit oversimplified). This happens over and over again throughout the universe because the forces are everywhere - gravity, light, and electromagnetism, for instance, are common and they react each according to their natures; and because their natures are not random natures, they do not interact randomly: gravity doesn't randomly become light and then magnetism, for instance, and it doesn't randomly change the way it interacts with the universe.
True, constants may actually change over time (there are debates about just how constant constants are), but overall forces have a nature to them, a pattern to them. And patterns interacting with patterns, and you get great variety of results, but it isn't chaos. Same with biology. There will be universal biological laws. And given the right range of conditions, and life will arise again and again in the universe, just like stars die and stars are born, they didn't come into existence only once, to die as a one time occurrence. Galaxies weren't created only once. There is an overall evolution to the universe (change may be the only true constant), but it is a slow evolution, and right now life exists, and we are learning more and more just how tenacious life is. It survives terrible calamities, terrible upsets - particular life forms may not survive, but life itself tenaciously persists.
Zimmer, Carl. "Aliens Among Us." Discover. July 2007. 62 - 65. Can also be found at <http://discovermagazine.com/2007/jul/aliens-among-us>.
Scientists, including biometerologist Nancy Kiang of NASA's Goddard Institute for Space Studies, have been speculating to the color of alien life in response to the type of star, or even atmosphere, of their planet.
Plant like life would probably be fairly common since starlight is a very useful, and fairly constant source of energy for life to take advantage of. On the Earth, for instance, phytoplankton (microbial plants) are extremely abundant and "provide the basis for most of the marine food chain, half the oxygen in our atmosphere and ultimately much of the life on Earth" ("Breakthrough").
Studying plants on Earth, the scientists discovered something: at first plants seem rather inefficient because they reflect light at its highest energy output - green light. The sun light energy that hits the surface of our planet actually peaks in the green band. However, photosynthesis uses particles (photons) of the light rather than just the energy. The photons peak in the red range. This is because red light penetrates through the atmosphere easier than blue light which gets scattered mainly by atmospheric ozone (which is why the sky looks blue, and the sun appears to be red when it is setting - the light from the setting sun has to travel through more atmosphere than the noon time sun, and the only light that makes it through with the least scattering is red).
But even though blue light is scattered somewhat by our atmosphere, enough still reaches the ground that plants can find it useful; while photosynthesis relies on photons, more energetic photons tend to be more efficient - blue photons are far more energetic than red photons. Though there is a limit as to how much energy a plant can take in. For most Earth plants, concentrating on the peak in the red range is enough.
By the way, while the sun puts out more light energy in the green band, it looks yellow to us on the surface because, as mentioned above, some of the blue is being scattered by the atmosphere. From space, the sun looks white, but that is because of how our eyes work - when flooded by the entire spectrum, especially from a bright source, our eyes will perceive the source to be white, even if it is not fully white.
Using this information about photosynthesis, Nancy Kiang and her fellow scientists speculated what color life would prefer in alien environments. F-type stars, for instance, are hot blue stars that give off more blue photons than photons of other colors, and definitely far more than the sun. On a planet circling such a star, any plant like organisms that finds the chemistry of photosynthesis to be as useful as do Earth plants (*), then such plant like organisms may want to concentrate on absorbing blue particles. They would probably reflect red and orange, since those wavelengths are of little use (not efficient to use them).
Around cooler, and dimmer, red M-type stars, the light may be so little that plant life will need all the particles they can get, and thus they would reflect little to no light back (black plants - a goth planet!). Even if the plant life used chlorophyll that absorbed mostly in the infrared range (scientists have discovered two types of chlorophyll on Earth that absorb in the infrared range), such plants may want to absorb as much heat as possible. Or for a planet or habitable moon circling a gas giant far from the central sun, with a thick atmosphere (reflecting even more of the blue wavelength that our atmosphere), plants on such a planet may need to use all available light as well. (Note: Apparently solitary - not binary - red dwarf M-type stars are the most common in our galaxy).
What would this mean for sentient cultures? Just that each section of their spectrum could easily have rather different cultural significances or cultural or theological metaphors. Think of what yellow means to us: warmth, light, day, energy - it is a positive color. Red is connected to blood, and often means life, and from spilled blood, sacrifice or death. Blue is a color of coolness, water, and sky. And of course green is for food, sustenance, fertility, serenity, and life.
Around different stars, these colors could easily take on other meanings. Around a hot blue star, blue may not be a color of coolness. The sky may very well be blue, with a brighter blue spot for the sun - which could be interesting. Think about what if our sky was yellow? Our yellow sun would be this bright part of the yellow sky, a bright spot that moved. Maybe we wouldn't be able to tell exactly the boundaries of the sun and so not, at first, recognize it as a self contained body circling the Earth, but instead just a brightness that moves across the sky. So too, possibly, for some planets circling a blue star.
On a planet with black plants, black could come to represent, to the primitive sentient mind, life. And if black was food, sustenance, fertility, and thus life - then what of the black night sky?
And what of a planet that had both blue water and blue plants? The color blue could take on such a huge significance. Maybe even some of the animal life would have blue pigmentation (to blend in with the vegetation, for instance). However, Ms. Kiang feels that totally blue is the least likely color for plants, since blue light has very high energy photons.
Speaking of red stars, class M stars tend to flare more than sun, and more strongly. This can cause problems for life as the flare floods the planets with strong radiation. However, life is tenacious, "life always finds a way," and not only are there small life forms on Earth that can survive in outer space, but water is a good shield - life forms 9 to 10 meters below the surface would be protected from the flares while still getting enough life giving photons.
* Because of the universality of the laws of physics and chemistry, it is conceivable that there are universal laws of biology, which are based on physics and chemistry. Not all biologies may discover photosynthesis, as there are many chemical and physical variables within those universal laws, variables that may vary enough that some biologies may not "discover" or even need photosynthesis, or may find alternative versions of photosynthesis that are not needed or were not "discovered" by the biology of our planet. However, chlorophyll is a remarkable molecule; it is a very useful source of energy production for life and so seems highly likely to be popular among life in the universe (though again, that does not rule out exceptions).
Estimates the number of advanced Milky Way galaxy civilizations we potentially could communicate with.
For more information see my Introduction to the Drake Equation post and related posts with label Drake Equation.
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