|What the sky might look like from Gliese 667C; BBC|
This is the region where temperatures ought to allow for the possibility of liquid water,although no-one can say for sure what conditions are really like on these planets...
The planets would need an atmosphere to sustain liquid water on their surfaces, but at a distance of more than 200 trillion km, there are no means currently to determine what the precise conditions are like or whether life would have any chance of establishing itself.
Nonetheless, Dr Tuomi believes M-dwarf stars are good candidates to go hunting for potentially habitable worlds.The fact that these three planets could have liquid water "...single-handedly demonstrates that low-mass stars can be hosts of several potentially habitable planets," explained one of the investigators, helpfully. We've seen this many times before, cosmologists using 'life' to mean 'life as we know it', the marketing criterion by which to get discoveries of orbiting rocks into the mainline news.
Whether these planets have any atmosphere is a trivial detail that current research can't answer. In part, this is because the planet is a mere 22 light years away (about 200 trillion kilometers!). The star is about a third the size of our sun, and the planets about 3 times the size of the earth. These planets, the story hopefully enthuses, have annual orbits of 28, 39, and 62 days. Because the pseudo-sun is smaller and cooler (it's what is known as an M-dwarf star), planets can be closer to it than the earth is to our sun and life still may have evolved there, and they can orbit fast without being singed beyond recognition.
Now, finally! We have planets that might plausibly (and hence the news writers and scientists would like us to assume, must) have life. And just imagine what it's like!
Twitter, twitter, little star!
Life on Gliese 667C would be quite a whirlwind. Let's take 40 days as the typical orbit. Days and nights, and years, would (literally) race around like cars in the Indy 500. A message as long as this would take a week to write. For poor students, a 15 earth-week (say, 100 days) semester would take 3 Gliese 667C years! Students would reach retirement age shortly after graduating. And don't get too fond of your pets. With a 10-year lifespan, kitty would only last 400 days--about one earth year!
Indeed, circling this little star so quickly would have taught everyone long ago to communicate fast. We hypothesize that Twitter was invented on Gliese 667C, and somehow transmitted to earth. With the world, so to speak, passing by with such dizzying speed, one would not wish to dawdle over every correspondence. A long-time earth friend you've known for 5-10 years would be the equivalent of a Gliese 667C friend you met only a couple of hundred days ago. We'd all have to wolf down our food to prevent noticeably aging during a single meal. And nights would not last long enough for even a single 90-minute dream cycle!
The implications of life in the fast-orbit are dizzying. It seems almost impossible to imagine. And contemplating life on Gliese 667C raises further very serious and perhaps even more profound questions, that lead us (ever the skeptics!) to doubt claims or hints that life really does exist on Gliese 667C. Here are some of the problems.
Is life in the fast-spin possible?
- Life heavily depends on the annual cycle of seasons. For example, mating takes place in the cold season when many creatures are hibernating or pupating, so that young are born in the spring when their prey are hatching. Because embryos take time to develop, if the year is too short, they will be born at the wrong time relative to their food sources.
- Similarly, many plants shed their leaves to refresh their growth after an off-season. Deciduous plants require fertilization from insects who are active (and hence whose larvae have matured) when the leaves are new and the plants are in flower. It's true that on earth bees and plants and other animals have different gestational times from fertilization to maturity, but winters need to be long enough for that to happen, and that takes months rather than just a few days. The short days and weaker amount of light from this lesser star would also play havoc with chloroplasts' needs for enough light to achieve enough photosynthesis in the brief daytimes, so trees might not be able to grow big enough nor produce enough nutrient energy to support their leaves, limbs, roots, flowers, and seeds. Bad news for the squirrels, bees, bugs, and even woodpeckers. Apples won't have maturing time to become, well, actual apples. They'll just be tiny runts.
- At the same time, the lesser energy may yield far fewer thunderstorms and hence fires to clear the vegetation for forest health. And this in turn may also not provide enough tropical rainforest to absorb enough CO2 or release enough oxygen as needed for other life on the planets. And the growing seasons might be so short that only bonzai trees could survive, providing no sustenance or low- (or high-) hanging fruit for insects or mammals.
- We don't know whether these exoplanets have atmospheres or not, but if there's life then of course they must. But whether the 'air' would be dense enough for bird or even insect flight, or pollen dispersal, is highly problematic. There must of course be sufficient oxygen for breathing as well as to provide a shield against dangerous cancer-causing UV radiation from Gliese 667C.
- Sea life depends, at least for animals, on buoyancy, which requires that the salt content of the exoplanetary seas be suitable for algae, crustaceans, fish and sea mammals. Likewise, the evolution of land life from sea life requires sufficiently strong (but not too much!) gravity for support by bony structures, so the expansion onto land would allow mobility for searching for prey or escaping predators.
- Even the climate makes a difference. Spring runoff and the like provide fresh water when more animals are active. Tectonic (geologic) activity is needed to shape the land and sea and its interface and even to provide some minerals and building materials for life. But would it be fast enough, or too fast?
Of course, we're just spoofing here. When cosmologists and the media (including sci-fi writers and Hollywood) talk about 'life' elsewhere, they almost always mean 'intelligent' life and even human-like life. Talking about 'habitable zones' reflects this. Yes, carbon, oxygen, water and the like are vital to life here, and could be important elsewhere. But it is only a paucity of imagination, and a penchant for self-promotion, that leads to reports like this being treated as more than just the discovery of a few rocks in space.
Life need not be as we know it, or perhaps we have so provincial an understanding that the word itself really means our kind of molecular activity. What other forms of self-perpetuating activity might exist, in or out of 'habitable zones', who can say?
Gliese 667C is a very close star to us, as these things go. For starters, there are 56 stars known to be less than 17 light years from the earth (e.g., Wikipedia 'List of nearest stars'). These are, of course, stellar systems as dead as doornails as far as we can tell. We get no radio rock music emanating from them. So we must go farther afield to find our nearest neighbors.
But even as close as 22 light years, which is much closer than most other stars even in our own galaxy (which is about 100,000 light years across) not to mention other galaxies, even if there were human life on Gliese 667C, and even if they were, unbelievably, in the same fleeting fragment of their existence to use electromagnetic (i.e., radio) means of distant communication, and even if they had some sort of 'language', and even if they were curious about what aliens might exist out beyond Gliese 667C, just to set up communications would take lifetimes (44 years just to exchange one message, and how many cycles to learn to read each others'?
Let's think about this. There will be no Rosetta stone signaling from space--signals with translation into an earth language. Decoding ancient (simple) cuneiform tablets, like the famous Mycenean Linear B from the ancient Mediterranean world (see below) took a lifetime and more of scholarly work to understand and translate.
|Linear B: Wikipedia|
Actual travel even at high but imaginable speeds (assuming light is the fastest way to go and approaching it would require ginormous amounts of fuel energy), a one-way trip to Gliese 667C would take longer than hominids have existed. So even contemplating contact, even with a nearby star, even having human-like intelligence (if that's not just a self-flattering term!), verges on putting us in a mind, much less a time, warp.
Is there life out there? We've written about this before here on MT. Given that there are on the order of billions of galaxies, each with billions of stars and hence likely multiple billions of rocks orbiting around, it would seem implausible that there is not a variety of forms of 'life' all over the place. But while it is entrancing to muse about, it is to a great extent not even a scientific question to ask. It is musing, it's philosophy or even religion perhaps, but it's not science.
|ET; The Guardian|