21 January 2010

Obama announces support for renewal of Glass-Steagall

OK, amidst all the bad news, something good. It's a start.

My e-mail to President Obama

I have written to the White House numerous times before, urging the President to give up on conciliation with the enemy, and urging him to adopt a more populist progressive stance, and to get smart about the necessity of framing the issues in a way that communicates an emotional message to overcome the propaganda manipulation of fear which the Right Wingers have become so very good at. George Lakoff and Manuel Castells have written very cogently on this subject. See also the excellent comments of Matt Taibbi in the Village Voice on what is needed in the way of reframing the progressive message.

The president seemed to get this, at least to a great extent, during the campaign, but, frankly, his governance has been abysmal. We are the verge, if not over the verge, of complete failure.

The president must listen to new voices. He must abandon those who advocate compromise and conciliation with the Right, because it could not be clearer that the Right… virtually all Republicans and some Democrats, such as Nelson and Lieberman, will stop at nothing to block and impede the President’s efforts to change the message from “government is the enemy” to “we need good governance, and reform, to ensure that the interests of ordinary people are put first.”

The president needs desperately to not only change the tone of his message, but its substance as well. He must clearly and squarely oppose those, even in his own administration, who refuse to recognize the need for sweeping financial reform. He must embrace a truly progressive agenda, and not approach every issue by proposing the compromise before the negotiations even begin.

Yes, we are in a real pickle legislatively. But the president must LEAD us out of it. Demand, in the state of the union, that the Senate be run on a majority rule basis, and ASK the people to write to their Senators and make this demand. Fight like hell, giving no quarter, to elect Democrats who will actually support a Progressive agenda, and leave those that won’t in the cold. We have to build a legislative majority… it may take a few years, but if the President truly changes course now it can be done.

Otherwise, the President will have already been defeated, and the Right will regain power sooner rather than later. The choice IS as stark as that. Mr. Obama, I implore you: get smart. It's all out war. Slash and burn; use every tactic; learn from the Right Wing the power of message and propaganda, and fight like the future depends on it (because it does). The future of the whole world is at stake.

What a week

What a week. First, the Massachusetts electorate votes in an idiot from the Torture Party to replace Edward Kennedy. Now the Supreme Court, in Citizens United v. F.E.C.,  has effectively gutted campaign finance law and handed the power to buy elections and representatives without much restraint to corporations, based on some of the most irrational legal reasoning in decades. Now, Nancy Pelosi is effectively conceding that Health Care Reform is a lost cause. Sheesh.

Politics is becoming unbearable in this country. Something's gotta give: I cry out for Progressives to get smart. It's all out war. Slash and burn; use every tactic; learn from the Right Wing the power of message and propaganda, and fight like the future depends on it (because it does). The future of the whole world is at stake.

20 January 2010

Where are they, then?

Sixty years ago Enrico Fermi asked this question when the discussion of the prevalence of extraterrestrial intelligence came up. It's a fair question.

Over the past fifty years or so, various writers, some very carefully examining all the known facts, and others perhaps a bit less careful, have addressed the question of whether it's realistic for the human race to expect to encounter alien technological civilizations (usually the expectation being that they will be contacted by radio). Frank Drake came up with the famous Drake Equation in the early 1960s to attempt to give a number to the technological civilizations in the Galaxy (let's call them, rather, spacefaring, meaning that they have made themselves detectable from outside their own home star system). The problem with Drake's "equation," as variously treated by different authors, is that virtually all of its terms, beyond the basic physical facts about the Galaxy and its stars, are pretty much informed (at best) guesses, some usually pretty clearly colored by wishful thinking. The factors are designed so that the number of spacefaring civilizations will equal a fraction of the number of stars in the Galaxy, by estimating how close to unity various factors are. Some of these are: How many (i.e., what proportion of) star systems have planets with living organisms? How many of these develop complex multicellular life? How many of these develop intelligent life? How many of these develop outer-space technology? (E.g., there's no sign that Earth's dolphins, who may well be as intelligent as we, will ever do so; which begs the question of just what is intelligence, anyway, and how biased is our view of what it essentially is by our own characteristics as a species?) How long does an average spacefaring civilization last? (This of course determines how likely we would be to encounter any given civilization in a given period of time). The original Drake equation ignored the physical evolution of the Galaxy, whereby in its earlier phases the likelihood of intelligent life was presumably zero, since the interstellar medium from which stars formed was pretty much devoid of the necessary elements for the evolution of life for the first billion or more years of the Universe's (and therefore necessarily any particular galaxy's) lifetime.

In any case, there are no definitive answers to any of these questions, and estimates have tended to be on the rosy side. See this post for reasons to believe that complex life, and therefore intelligent life, may be a good deal rarer in the universe at large than formerly thought. Many of the Drake factors could well be very low, in which case spacefaring civilizations could be quite rare... or we could even be unique in all the Galaxy. I think it cannot be dismissed that there may be some number well above zero (one, really, counting us), on the other hand, but the fact is we don't have a lot of evidence from which to make informed estimates, so people's proclivities and wishes tend to infect their estimations. 

Most scientifically minded people allow that conditions similar to the early Earth are probably not all that rare, and that life is likely to arise in such conditions, although even this is debatable. There are those who, not resorting to any kind of religious argument or metaphysics at all, nonetheless conclude, using Occam's Razor reasoning with regard to the likely permutations of molecules, that life may be a fluke, so unlikely to arise that it is probably unique to Earth in all the universe. Personally, I'm convinced by explanations for why a purely probabilistic analysis of how likely it is, for example, for DNA molecules to arise spontaneously from simple organic precursors, are not realistic. See, for example, the excellent work of Christian René de Duve on the origin of life. I think there's a good intellectual case to be made that basic living systems, comparable to bacteria, at least, will arise in time wherever the conditions are present and stable long enough for it to do so.   

I have not yet read Jack Cohen and Ian Stewart's Evolving the Alien, but from what I can gather their thesis is that we need to expand our thinking about how and where life may evolve, and not merely assume that a planet much like Earth is the only possible place of origin. Fair enough, but I don't see how most of the observations I talk about here are affected much by widening the scope of exobiology a bit; the facts about evidence or lack thereof of its presence remain. I am not arguing that intelligent beings do not likely exist elsewhere than Earth. I am only arguing for a certain perspective and realism in discussing this subject. 

It's generally been accepted by most who have written about this subject that the Earth and its Solar System bear no evidence of ever having been actually physically visited by alien beings (or by their machines), UFO true believers notwithstanding. I would have to call this an open question. We have hardly explored the Solar System in sufficient depth, and our knowledge of the form that alien technology might take is sufficiently paltry, that no definitive statement to the effect that we have never in our planet's 4½ billion year history been visited by alien intelligence, is possible. Still, there is no positive evidence either, so at least we can say that there doesn't appear to be any active visitation going on. Of course it isn't possible to absolutely rule out the Galactic Zoo hypothesis, whereby we are under clandestine observation by aliens careful to conceal their presence, but in the absence of actual evidence for this, it remains purely speculative. To my personal prejudices, I consider this idea just short of silly and not at all likely.

Technically, indeed, as discussed above, the existence of any life of any kind anywhere other than this planet is speculative, but given what is known about the depth and breadth, as well as the essential sameness of the stars and galaxies which comprise the vast universe, I take it as a reasonable supposition that life, if it could evolve once, must surely have done so countless times, in sufficiently similar contexts; and that, however rarely, nonetheless somewhere and at some times, it must have evolved into beings to some arbitrary degree comparable to ourselves. People with certain religious--or other philosophical-- views (e.g. Ray Kurzweil) will reject this notion out of hand, but holding an opposite view, it seems to me, is what requires special pleading: it is actually hard to imagine that what has happened here has not happened, in essentials, elsewhere. The essential, really unanswerable, question, is how often? Are beings comparable to ourselves common in the universe, vanishingly rare, or somewhere in between? The fact is, we just don't know.

So what can be said? Not a great deal, definitively, but there are some additional factors that need to be taken into account.

What about machines visiting the Solar system in the past and having left evidence? As noted, this can't be ruled out. But how likely is it that some past civilization would have actually done this? The brilliant theoretician John von Neumann is credited with first conceiving of self-replicating machines, sometimes called Von Neumann Machines. Elaborating on this a bit, the idea is that a sufficiently advanced technological civilization is likely to wish to explore the galaxy, and to do so, eventually, it is likely to build spacecraft which use Von Neumann's idea: they would be capable of using raw materials they encounter in space to construct copies of themselves, to proceed further, possibly in exponentially increasing numbers, to explore star after star, reporting back to 'home base' (the programming is reproduced as well). It is a pretty simple calculation to realize that, even without fantasizing about unknown physics allowing faster than light travel, or particularly exotic energy technologies, such systems would be at least theoretically capable of visiting every last one of the 300 billion stars in the Galaxy is a small fraction of the age of the Galaxy. I've seen estimates of perhaps one to no more than a few million years for such a project, to explore a galaxy that (like all galaxies) is something on the order of 13 billion years old. Is this possible? Since it's never actually been done, as far as we know, I don't know that anyone can really say. Maybe even if some particularly relentless and determined explorer species tried this, their program might fail just from the inevitable incursion of noise into the programming. But the multiply redundant code of DNA in living genes suggests that sufficiently detailed and exact information can be preserved sufficiently intact over tens or hundreds of millions of years, so this doesn't seem to be a legitimate objection, at least in principle.

The Scottish science fiction writer Iain M. Banks has publicly dismissed the whole Von Neumann Machine scenario on the grounds of aesthetics. It's just so mechanical, and ultimately, boring, he would argue. What conclusion can be drawn from any of this? I would say only that advanced civilizations capable of building self-replicating automatic exploration machines, if they have ever existed in this galaxy, are (in all likelihood) not currently active and have not left any very noticeable traces here in the Solar System. Can this scenario, having happened in the past, or likely to happen in the future, be ruled out? No, but beyond that there really isn't much to say about it.

So what about "SETI," the search for extraterrestrial radio communications? SETI enthusiasts always say that their search is just barely begun, and that it isn't realistic to expect them to have succeeded by now, because the Galaxy is so vast, and the available bandwidths and modulation potentials for communication so various and extensive. But is this really a reasonable point of view? It seems to me that the whole premise of SETI is that other civilizations will be actually a lot like us, using electromagnetic waves to communicate by superimposing artificial patterns on them, and further that any such civilizations will continue to do this for long periods of time, so that there would be a reasonable probability that they would exist and be doing this concurrently with our existence, and we might detect this activity passively. I think this is at best an untested guess. We may well have advanced in the relatively near future to the point where we no longer use leaky EM broadcast signals for any form of communication. Maser or Laser communications (tight-beam) would probably not be detectable by anyone not their intended recipients over any great distances of space, and this technology already exists. To my mind, the fact that we have not detected other civilizations from their communications is not surprising, but it also doesn't tell us much about how likely other civilizations are to exist, and not, or not only, for the reasons the SETI folks suppose. It may just be that they are on a fool's errand.

What does the fact that there's no obvious evidence of visitation to Earth by extraterrestrials at any time in the past tell us about the likely potential for space travel? Here, I think, the implications are clear, and they are not what many space enthusiasts like to believe. Let's make some assumptions and see where they lead us. Assume that there have been in the Galaxy some substantial number of civilizations which have well exceeded our level of technology, over the at least few billion years that stars a lot like the Sun have existed, such that at least potentially a civilization comparable to ours could have arisen. Assume that some reasonable fraction of these persisted, or continue to exist, for long periods of time, such as at least many thousands of years (making it likely that some exist now). Next, assume that we have not learned all the fundamental laws of physics, and, after all, despite all the sound reasons what we have learned tells us otherwise, it turns out that it is feasible to build starships, wonderful engines of technology that can transport beings and materials from one star to another at speeds faster than light. And at least some fraction of these putative past and present civilizations have discovered this secret, and actually built such things. Star Trek!

Well, there is a serious problem with the implications of these assumptions in combination. It's the Von Neumann implication all over again, only moreso. If a civilization with even a very modest rate of natural growth and stable technology capable of traveling between stars at faster than light speed (if that were even possible) existed, and if it persisted for a few tens of thousands of years, it would have plenty of time to visit every single star in the Galaxy. If it persisted for millions of years, it would have had time to visit a few of the nearer outer galaxies as well. And surely, with all that awesome power, it would, somewhere in all the vast cosmos under constant observation by thousands of terrestrial astronomers, have left some evidence... some radiation that didn't fit a natural cause; some star whose energy signature was obviously artificially modified, some artifact somehow detectable using the powerful telescopes and other means of detection at our disposal. To my mind, all this seriously strains credulity. The fact is that nothing has ever been discovered which is even seriously suspected of being the product of an advanced technological civilization. I think the fact that we live in a quiet galaxy, where to all appearances our Solar System has remained undisturbed for billions of years, speaks volumes, and what it tells us, if we have ears to hear, is that no technology exists anywhere which can transport matter or even signals faster than light. This is an actual limitation, a real barrier, imposed on us by the nature of reality in our universe, that is and has always been an effective limit on the ability of any organisms anywhere to travel or propagate themselves in space. No amount of scientific or technological progress is going to change this fact, ever.

To those who might object, "what if they just didn't want to visit every star?," I'd have to say, well, maybe so, but surely in all of the Galaxy, and in all that time, if this were possible, and if such civilizations existed in any numbers, someone would have done this. I think the conclusion is all but inescapable that a Star Trek type universe, with tens or hundreds of concurrently existing spacefaring civilizations, all capable of traveling faster than light and zipping around the galaxy in small fractions of their individual lifetimes, will forever remain a fairy tale.  

The fact that, for reasons I don't have time or space to go into here, travel at speeds faster than light is the exact functional equivalent of time travel, and that both of them violate fundamental laws of causality, is at least suggestive that there are very good reasons why faster than light travel is and always will be impossible.  

The fact is that stars are very, very far apart (see this), and travel between them takes a very long time, in any vehicle likely to be developed, even by advanced technologies. It is also likely to remain expensive, in terms of fraction of resources that a civilization would likely as soon devote to other uses, although a sufficiently advanced civilization may have resources to freely spend without much care. So, generally, star travel is likely to remain essentially infeasible, except, conceivably, for one-way colonization and/or exploration missions. Extremely long lifespans of the travelers could change this, but it seems to be a real limitation. This is a subject of much speculation, which I will defer for another discussion, except to say that these same considerations would apply, and would have applied, to other civilizations as much as to our own.

Another subject of much speculation is whether machine civilizations might come into existence. There has been a fair amount of speculative fiction written on this subject. I have rather definite views on the possibility of machine consciousness (not), but I will defer that subject as well, and merely observe that whether you are talking about biological civilizations, machine civilizations, or hybrids thereof, makes little difference for this discussion. Assuming, that is, that machine civilizations must necessarily arise originally as byproducts of the civilizations of living beings. 

I will also leave alone any metaphysical speculations on the existence of nonphysical entities, whose intelligence and presence may not be observable conventionally. This is a fascinating topic, but it has no direct bearing on the issue, which assumes ordinary physical existence as a starting point for discussion.  

What about advanced civilizations' artifacts? Freeman Dyson and science fiction writer Larry Niven postulated, respectively, "Dyson spheres," huge spherical artifacts which contain a star at their center and host living space on their inner surfaces; and "ringworlds," bandlike rings orbiting stars at roughly earth-distance, with habitable inner surfaces. Iain M. Banks modified the ringworld idea to postulate what he calls an "orbital," a rotating ring about 3 million km. in diameter, orbiting a suitable star, which could be spun to have approximately Earthlike centrifugal gravity equivalent on its inner surface, and, as it works out, approximately a 24 hour cycle of light and dark, just like a planet. These fictional future technologies (or current or past technologies of hypothetical advanced civilizations elsewhere) are, to say the least, conjectural, but even if they exist, in large numbers, would they be detectable? I'm not sure of the answer to that. I've seen it speculated that a Dyson sphere, at least, would be noticeable within a certain range. It would be a dully radiating infrared source, emitting all the energy of its concealed star. Such an object would be detectable for quite large distances, and would be sufficiently unlike any natural objects to raise some red flags. Conceivably, the smaller versions might exist and go unnoticed, but this at least suggests that civilizations that use all the energy of their home stars are not common, if they exist or have previously existed at all.

The Russian scientist Nikolai Kardashev pursued these ideas to a logical extreme in the 1960s, postulating the existence of different levels of super-advanced civilizations, with Type I consuming all the energy of a single star, all the way up to Type IV, which would consume the equivalent of all the energy of the entire universe. On this scale, we aren't even at Type I -- far from it. Looking out into space, we do not see any obvious evidence of civilizations which are using all the energy of their star, and re-emitting it as infrared. Still less are there any reasons to suppose that any of the fascinating objects observed in the Galaxy or beyond is the glow of the waste heat of a supercivilization. To my mind, all of this is pure fantasy, with the possible exception of advanced cultures that use some considerable fraction of the light of a star, and might eventually be detectable as a result. It seems to me looking for such things might actually be worthwhile. Certainly actually finding one would be of earthshaking importance. But the idea that there are civilizations anywhere using all the energy of a galaxy seems to me fanciful in the extreme, particularly in the complete absence of any actual evidence for even the lesser 'classes.'

So what can we conclude from all this? Where, in fact, are they? I think from what we observe we can conclude that advanced technological civilizations, at our level or above, are not, and have not been in the past, very abundant. If they were, over long periods of time, it seems to me reasonable to assume that there would already be some evidence, somewhere, of their existence.

For all intents and purposes the Galaxy has been more or less as it is now for billions of years, so other worlds could have formed earlier than Earth (or later, for that matter, since rates of evolution are not necessarily uniform)... and reached an equivalent of Earth's current evolutionary phase many millions of years ago. Therefore, there is no reason to believe, at least in terms of hundreds of thousands or even millions or tens of millions of years, that there is anything special about this time, as opposed to some earlier time. So civilizations could have arisen and surpassed our technological level, persisting for long periods of time, at least some tens or even hundreds of millions of years ago. Had any significant number of them at any time reached a level where their presence was likely to leave unmistakable traces... artifacts sent roaming the Galaxy to search for life; huge space arcologies, whatever... it seems likely that some residual evidence of that fact would persist and be detectable, somewhere in the vastness of the Galaxy. Is there such evidence? We can't be sure, because our technology for detection remains of uncertain prowess. We have not exhaustively explored places like the Moon, where there is no erosion, and where small artifacts from an actual visit remote in time could remain. Also, the works of a civilization at any distance, particularly one which has ceased to function, could well be completely undetectable. But still, the absence of evidence, while, in the famous formulation (attributed to Carl Sagan), not being evidence of absence, is nonetheless suggestive: it seems to me that we should accept as an operating assumption, since there is literally nothing in all the observational history of our world that can reasonably be ascribed to extraterrestrial life, that many of the factors in the Drake equation are a good deal less than one, and that advanced civilizations are not really all that common, nor necessarily all that long-lived when they do arise.

To my mind the facts point to a tentative conclusion that space is vast, and likely mostly empty of beings (to whatever arbitrary degree) "like" ourselves. I find it hard to imagine that intelligent beings haven't existed, and don't continue to exist, elsewhere in space, but space is really, really big, so we could well be alone in a huge volume, which could mean communication with or even detection of extraterrestrial civilizations may just not be effectively possible. Maybe someday we (or our remote descendants) will find and somehow converse with our like out there somewhere, but there doesn't seem to be any good reason to expect this to happen any time soon. 
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Taking a Break

For my few readers wondering at the recent spate of posts on, shall we say, philosophical, issues: I am taking a break from commentary on politics for a while, for the I suppose obvious reason that what's been going on both in my home state of California and in Washington these past several months is so profoundly disappointing.

14 January 2010

Link to article on "Where are they?" (i.e., the Fermi Paradox)

An interesting article on the "Where are They?" question (so-called Fermi Paradox) from Scientific American a few years back. I will post a few of my own thoughts on this subject later.

One glaring fallacy in this article is the assumption that technological civilizations would likely form at a more or less constant rate since the origin of the universe. Without going into long explanations, I'll just say that assumption is obviously wrong and defer further comment.

09 January 2010

Galaxies and Life; why not all galaxies are created equal

The Milky Way Galaxy, our home (in a very broad sense), is what's called a barred spiral galaxy, with something like 300 billion stars. When I took Astronomy 101 in college more than 35 years ago, that sentence would have left out the word ‘barred’ and would have said ‘100’ billion stars, but knowledge is always changing, and in the field of Astronomy, understanding has progressed in the last hundred or so years literally by leaps and bounds.

300 billion is a, well, astronomical, number, so large that we can hardly imagine it, even though we use the same kind of numbers for dollars… which we don’t really grasp either. The mind fogs at the prospect of such numbers. But despite this huge number of stars, a galaxy is almost entirely empty space. Typically there are only one or two atoms per cubic meter on average. All those stars are set amidst an incredibly tenuous gas, which in some places is a bit denser, less so in others, but nowhere, other than in actual objects like stars, comets, and planets, anywhere near as dense as air, just as an example. And the stars are almost unimaginably far apart. Around here (out in the disklike plane of the Galaxy, about 30,000 light years (~250-300 quadrillion kilometers) from the center), stars are typically roughly 3 to 5 light years apart (and this is a slightly denser than average region). A typical star is smaller than the Sun’s roughly 1.4 million kilometer diameter, and the typical distance separating typical stars translates to something like 50 trillion kilometers.That's still an almost unimaginable distance. At the escape velocity of a rocket leaving the Earth, it would take over 100,000 years to get to the nearest star.


M31, the "Andromeda Galaxy;" about 2 million light years distant

That’s hard to imagine. So picture this. If the Sun were a basketball, the next nearest star, which happens to be roughly the same size, would be about 10,000 kilometers away (Alpha Centauri A, ignoring its slightly smaller companion and much smaller distant companion, which just happens to be a shade closer, Proxima Centauri). That's Los Angeles to Eastern Europe. The Earth, in contrast, would only be about 50 meters away. So, you realize that on the interstellar level, the universe is very, very empty, and stars are very very far apart. Two galaxies can pass right through each other without a single stellar collision; in fact it happens all the time, in the grand scheme of things. The Milky Way is in the process of swallowing up a medium small dwarf galaxy right now, and will eventually swallow up its companions the Clouds of Magellan, and in turn be swallowed up after colliding with the Giant Spiral M31 in Andromeda (commonly referred to as the "Andromeda Galaxy"). But don’t worry, that’s billions of years in the future.

Galaxies are gravitationally bound systems of stars, with lots of gas and dust typically, although there are significant differences in their forms and histories that are very important for questions such as the origins of stars like the Sun and planets like the Earth, and, by extension, the origin of life as a sort of scum clinging to the surface of a few particularly situated such planets. Of course, there are all kinds of complications to all that. Galaxies all formed at about the same time, when the universe was cooling and expanding, and knots of density coalesced into, well, galaxies. Almost all galaxies have massive black holes in their central regions, which swallow huge amounts of matter and make the central regions not particularly hospitable. Galaxies, like everything in the universe, are actually mostly dark matter, the specific nature of which no one really knows, but for a basic understanding of what a galaxy is, and why some galaxies are likely abodes of living beings, including possibly, complex biospheres and intelligent creatures somewhat comparable to ourselves; and some are not, this will do as a basic description. They are all but unimaginably vast systems of stars, which can be categorized by their form or shape.

Galaxies are typically found in clusters, which form clusters of clusters. In the center of clusters, collisions are common, and most of the galaxies have already experienced collision and being swallowed up or swallowing up their neighbors. This has an unfortunate consequence for the eventual origination of life. Colliding galaxies, it turns out, typically expel a lot of their interstellar gas back into intergalactic space, where nothing much happens. This gas, however, is the stuff that stars are made out of. And so, galaxies near the centers of clusters typically stopped forming stars a long time ago. This is typical of what are called Elliptical galaxies (whether found in cluster centers or not). Ellipticals range from roughly spherical to elongated ovoids, and range from rather small galaxies to the very largest, in some cases hundreds of times as massive as the Milky Way (these kind have generally absorbed many other galaxies in the process of growing to this size over billions of years). This latter kind of galaxy is common near the center of clusters. Typically, Ellipticals (large and small alike) consist almost entirely of what are called Population II stars… older, very poor in metals (because they formed from what the universe was made of at the time, almost pure hydrogen and helium), and really kind of boring. Such stars can’t have rocky planets like Earth. They probably could never support complex biospheres because all the interesting elements; carbon, nitrogen, magnesium, potassium, phosphorus, oxygen, etc., etc.; necessary for life are pretty much absent. And since whole galaxies consist of these kinds of stars, with little or no gas and dust, and no new star formation, it’s a safe bet that these types of galaxies are essentially devoid of living worlds and life altogether. Wow, boring.

Then there are zillions and zillions of tiny dwarf galaxies, which are common in huge numbers in the general vicinity of other galaxies. These little dwarf galaxies, too, mostly consist of older, boring stars lacking complex chemistry, and almost certainly not capable of being the nursery of living worlds or life. (It turns out the universe is kind of like suds… the galaxies form the soap, and there are big voids where there’s pretty much nothing, but that isn’t really important. We’re talking about the volumes of space where there are galaxies in appreciable numbers. Our galaxy is located on a sort of tail end of a moderately large cluster, called the Virgo Cluster).

So what’s left? The spirals (and some of the irregular small but not tiny galaxies like the Large Cloud of Magellan). These include the barred spirals, more or less shaped like “S”, with a bar in the middle, like ours (this fact about the Milky Way has only been known for a few years). These galaxies are mostly quite flat and disklike, except for their spheroidal central regions and great clouds (haloes) of older stars and clusters that surround the entire galaxies in rough spheres. Picture a pair of CD's glued together, with a marble in the hole surrounded by a tenuous sphere of haze. That's the approximate proportion. Much of the mass is in the central regions, which are a lot like elliptical galaxies themselves, with energetic black holes in the centers of very dense regions, a lot of radiation, almost all Population II stars, and no star formation going on. The haloes of old star clusters and some individual stars are also old, Population II, and therefore lacking complex chemistry. So what’s interesting is the disk regions, which are where the spiral arms are, but also where there is a sort of general “disk population” of stars. The Sun is a disk star, located smack in the Milky Way's galactic disk, about 30,000 light years out from the center. (The disk is a bit over 100,000 light years in diameter).

Here, in these galactic disk populations, is we find active new star formation, and the enrichment of the interstellar medium from recycling of old exploded stars. This is where all those interesting elements beyond helium on the periodic table, which make life possible, come from. Stars which have formed later than the original formation of the galaxy in which they find themselves, and which incorporate this residue (these are referred to as Population I stars). These stars, of which the sun is one, are the kinds of stars that can have rocky planets, and, which, at least in the case of the sun, are capable of providing a suitable location for the evolution of life.

Spiral galaxies (including barred spirals, which are roughly half of them) together only make up about 20% of all galaxies, so right off the bat 80% of the galaxies seem to be unsuitable for the formation of living beings like ourselves anywhere in their vast reaches. There are probably some exceptions to this, since the morphology of galaxies is actually extremely complex, and many galaxies may have no new star formation but still have some Population I type stars, with metals (meaning everything heavier than helium) in their makeup. But however you look at it, not all galaxies are equally likely to be homes of living creatures. The beautiful flat spirals like our galaxy are the best candidates.

08 January 2010

Origin Questions and First Special Post: Rare Living Worlds

Most people don’t seem to have any real interest in what I think of as origin questions. I’m not talking metaphysics here… that’s a whole different area of human inquiry and understanding, and I’m definitely not dismissing it, but I’m talking about physical origins here. Questions about why there is something and not nothing, whether the universe exists amid myriad other universes, and what is the ultimate nature of reality, I will set aside. I’m also not talking about the ultimate physical origin of the universe as a whole, which is also a fascinating topic, about which much more is known than even twenty or thirty years ago. 

If you accept as a given that the physical universe had an origin, the Big Bang or whatever it was, and that a milieu of (all but innumerable) galaxies and clusters of galaxies, having certain composition and reasonably well understood dynamics, came into being some twelve or thirteen billion years ago and has been undergoing a sort of evolutionary process (including the accelerating expansion of the space containing them), ever since, that leaves a great deal to talk about in terms of how that milieu led to the here and now on planet Earth, and similar circumstances elsewhere. (The fact that there are an almost unimaginably vast number of elsewheres  is of course relevant, but this, too is a given).

Anyway, this is what I’m focusing on: the physical origin of the environment we live in, given the existence of the universe. This planet; its origin and history, in general terms, leading to the existence of a complex and relatively stable biosphere. Its star, the Sun, on which life on this planet unquestionably depends. The milieu from which the star and its system of planets arose: how, when, where, and what particular processes were involved. How probable it was for this process to have happened the way it did, which has obvious implications for how often something similar has happened elsewhere. The origin and potential alternative developmental histories of life on this planet, or on similarly situated planets. The fact that intelligent animals evolved, capable of manipulating their environment to the extent of possibly even escaping from the surface of their world of origin and going to live elsewhere, potentially replicating the essentials of their original biosphere in new locales (not happened yet, beyond a baby step, on this world). Necessarily related to these questions are questions of whether and how often the universe has produced conditions that have resulted in the evolution of beings comparable to ourselves: the Are we alone? question, and its corollary, first posed by Enrico Fermi more than 60 years ago: [If not], Where are they?

(The “Where are they?” question will be a whole post coming up).

So anyway, if you are one of those folks, the majority of humanity, clearly, whose eyes glaze over when these topics are brought up, and who prefer to simply take the world more or less as it is for granted, (since, quite sensibly, you conclude that there’s nothing we can do to change any of this anyway, so we might as well ignore it), then these rambling thoughts are probably of no interest to you, and you may as well break off right here. But I have been casually interested, as a lay person,  in these subjects for my whole adult life, and have read widely in the popular scientific literature on this subject. While I am hardly an expert, I do have a pretty good understanding, descriptively (as opposed to quantitatively), of the scientific consensus on the most important factors giving rise to the current state of knowledge and understanding in this area.

Of course, this is a huge topic, and serious students of its various aspects have written massive amounts touching on every aspect of it. But what I’d like to talk about is what it seems to me every intelligent person should know about it, particularly since a lot of what was and remains conventional wisdom on these subjects, as embodied in the mythos of the Space Age and Star Trek, turns out to be pretty much entirely wrong.

So bear with me, if you find this at all interesting. Watch this spot, as they say. When I get a chance, haphazardly, over some period of time coming up, I plan to post a series of what I hope will be thought-provoking ruminations on topics related to these questions, which I hope will be interesting and informative, starting with this one (below): Rare Living Worlds and the Origin and Special Characteristics of the Solar System and our World, and Implications for the Formation of Similar Worlds.

Some others I’m thinking about:
Why this is not (yet) the Space Age; what a Space Age might actually be like (and why the 'Star Trek' Universe does not and cannot exist).
Where are they? Are we the first (around here)?  
How and why not all galaxies are likely abodes of living beings (but don’t worry, there are lots of the kind that are).

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Rare Living Worlds and the origin and Special Characteristics of the Solar System and our World, and Implications for the Formation of Similar Worlds.

The Sun is what’s referred to as a ‘Main Sequence’ star. All this means is that it’s still in the phase of its existence where it is stable, and cooking along doing what stars generally do for most of their lifetimes: fusing hydrogen nuclei (also called protons) into helium nuclei (also called alpha particles) in their core regions (a process that produces a lot of energy, in the form of radiation). As it happens, the Sun is about halfway, maybe a little more, of the way through this phase, which commenced shortly after its formation from interstellar gas (and some “dust,” which just refers to other stuff, i.e, not hydrogen and helium)— that was present in the Milky Way galaxy in the region where the Sun formed. That was about 5 billion years ago, or something like 35–40% of the age of the universe. So the Sun is relatively old.

So what are stars? This is important to understanding what our world is and where it came from. Astronomy textbooks often just skip over this, but it’s actually not all that obvious. Why are there such things as stars anyway? The simple answer is that stars are great globes of incandescent plasma, consisting of the same thing as the universe is mostly made of, about 90% hydrogen, and 10% helium (with some contamination). Plasma is just is ionized gas. Meaning the electrons are stripped off the atoms because they’re so hot, and the electrons and nuclei are floating around in giant hot, very brightly shining, dense sphere, held together by gravity, not attached to one another. Of course it’s more complicated than that, but that serves as a basic picture. These globes form in the first place from gravitational collapse. Clouds of gas (contaminated with a tiny bit of other stuff— we’ll get to that)… in the vastness of space coalesce; they begin to collapse inward, as a result of various processes, not all that well understood. Eventually most of the gas in a particular region of space ends up in a particular place, and forms a roughly spherical ball of hot plasma. Turns out the question is, why doesn’t it collapse all the way to a point and just disappear? And the answer is radiation pressure (although, in most cases there wouldn’t be enough mass there for that to happen anyway, because it takes enormous pressure to actually dissociate protons into neutrons, or, even further, to dissociate them entirely, but it does happen when there’s enough mass collapsing: they’re called black holes).

Yes, light exerting pressure (it does, it’s just not noticeable in the environmental conditions we live in); that’s what holds stars together, preventing them from collapsing into even smaller bodies, which when they use up their fuel, they do (white dwarfs, neutron stars, black holes; but that’s a whole different topic). When enough gas, now plasma, collapses to increase the temperature and pressure to about million degrees Celsius (~Kelvin), nuclear fusion occurs. Protons fuse to become helium nuclei, releasing huge amounts of energy as radiation, which is where the star’s light comes from, after filtering up from the core to the surface. This was all worked out by Fred Hoyle and Margaret and Geoffrey Burbidge (among other people) back in the 1940s. Anyway, without focusing on the details, if there’s enough mass of hydrogen and helium for this nuclear fusion to occur at the core of the collapsing ball of plasma, a metastable state results. The pressure from the intense radiation of the fusion going on at the core holds up the outer layers of the ball, and before long a relatively stable, brightly shining star comes into existence. Later, the star leaves the main sequence because it’s ‘burned’ a lot of its hydrogen and it starts burning other nuclei, but that, too is a different topic. Stellar evolution is fascinating, but only its preliminary phase, the origin of normal, mid-life, hydrogen burning stars, is relevant to our topic.

Main-sequence stars vary, based mainly on mass, and to some degree on composition. The collapsing regions of interstellar gas that form stars vary from quantities not big enough to form shining stars at all (not hot enough for nuclear reactions), which form dully glowing bodies called brown dwarfs, glowing mainly only from the energy of their collapse itself (more like big Jupiters than stars at all, really)— all the way up to very massive, intensely bright stars that shine like beacons over whole vast regions of the Galaxy. More or less, though, the time that the star spends ‘burning’ hydrogen normally is inversely related to how massive it is. In other words, these bright beacons, these massive blue stars we see in our sky (like Rigel, for example), don’t live very long, and end up in spectacular explosions, sometimes after only a million or a few million years, in contrast to the Sun, which is already 5 billion years old.

You often hear the Sun referred to as a “garden variety” or “average” star. This isn’t actually true. Most stars (about 75% or more) are small, red dwarf stars, ranging from about a tenth to about 40% of the mass of the Sun. As noted, the lifetimes of stars are also more or less inversely related to their mass. So these small, very dim stars (much, much dimmer than the Sun), live a very, very long time. Far longer than the universe has even existed. They range from ten or eleven billion years old to recently formed, but all of them are young in terms of their own lifetimes, which can range up to over 100 billion years… again, far, far longer than the universe has existed. More below on whether life-forming worlds can exist in Red Dwarf systems, but for now, let’s talk about stars more or less like the Sun.

There is a class of stars (Class K) between Red Dwarfs (Class M) and yellow dwarfs like the Sun (Class G). These are what you might call Orange Dwarfs, and they live longer but are significantly dimmer than the Sun. It’s pretty much a continuum, although age of the star (stars grow brighter continuously as they age in the main sequence), and its composition (how much and what other stuff, other than hydrogen and helium, which astronomers confusingly refer to as “metals”) also affect its brightness and other characteristics. The Sun is most of the way to the brighter (and rarer) end of the “G” category, after which (brighter, shorter lived, and rarer as you go along), come “F” and “A”, and finally “B” and “O.” The latter two classes are extremely rare blue giants, so we can pretty much forget about them. They probably never have planets, and they live such a short time that life-bearing worlds could never form in their orbits, and together they constitute less than 1/4 of 1% of stars.  

So the Sun is somewhere around the 90th percentile of brightness, short-livedness, and rarity, of all stars. Hmm. So much for the mediocrity hypothesis of the Copernican worldview. Turns out our Sun is minimally exceptional. (We knew we were special all along, didn’t we? Just not too special).

Why is this important to understanding our world? Obviously, a star, to be the home star of a living planet like Earth, has to exist in a stable form long enough for that planet to evolve life, and there has to be a reasonable probability that a planet capable of supporting life will have formed at a spot where it receives, like Goldilocks, just the right amount of sunlight. Not too hot, not too cold. The sun fits this bill… it’s medium-bright, and it has a planet just where liquid water can exist, Earth.

Very bright stars don’t live long enough. Very dim stars have such small zones where the temperature is right that planets are actually quite unlikely to form there, and if they did, they are likely to be locked with one hemisphere facing the star all the time, like the Moon in relation to the Earth. That would be not too good for life. Also, red light is low-energy. It’s not inconceivable that life could evolve in a red-star system, but Earth life wouldn’t do too well there. Photosynthesis doesn’t work well in red light. Also, red dwarf stars typically flare a lot. Meaning their atmospheres throw out prominences that increase their brightness by a factor of two or even more. The sun does this too, but the prominences are trivial compared to the overall brightness of the sun, and at 150 million km. away, they are no danger to us. A planet a few million km. from a red dwarf could be cooked by a stellar flare. On the other hand, little red stars are really really common, and they live a long, long time, so life may very well exist on some worlds orbiting red dwarf stars, where conditions have turned out to be just right. Certainly, if life gets started, it should have plenty of time to evolve solutions to its environmental challenges. We shouldn’t expect, if we ever mature enough to explore such things, to find such life to be all that similar to life on Earth.

So, the sun is a medium bright, middle aged star. All these things appear to be pretty much necessary for the evolution of a living world like earth. Such stars are still quite common. What else about the Sun is favorable to life, and if such a factor were absent, life might be less likely, or, perhaps more specifically, complex multicellular life like Earth’s might be less likely?

First, it turns out that the Sun, compared to other stars of similar age (enough time for life to have evolved to a high degree of complexity), is very rich in ‘metals’ (stuff beyond helium on the periodic table). This is important, because it’s precisely this stuff, in which the cloud that formed the Sun was much richer than average, that formed the Earth, with all its trace elements necessary for life. Before I get to what is believed to have caused this unusual richness, we have to consider at least the possibility that it is a necessary prerequisite for complex evolved life. We don’t really know this, but it seems at least plausible. The formation of a rocky world with oceans and atmosphere just right for life, like Earth, would seem likely to be critically dependent on particular composition of the cloud of stuff from which it formed. We now know, from research into planetary detection, that other stars have systems of planets that do not at all resemble the Solar System. Many have massive hot planets very close to the stars. We can’t yet detect planets the size of Earth in orbit around other stars, so there are a lot of questions, but right now it looks like past assumptions that the Earth is quite typical may not be correct. It seems likely that planets similar enough to Earth (oceans, stable climate over long periods of time, nontoxic atmospheres, etc.) for complex life to form, may be rather rare. I’ll get to some additional reasons to believe this to be true later.

What caused the Sun to be rich in metals? Current thinking goes something like this. Stars often, maybe even always, form in clusters. The cluster that included the Sun was probably relatively small, because it has spread out to the point that we can’t really tell which stars in the star stream of the Galaxy formed with it, indicating that the cluster was small enough that in 5 billion years it's drifted into a diffuse population embedded in the general star stream of the Galactic disk. But the cluster in which the Sun formed was not too small, which we know because there is strong evidence (radiation effects on meteorites) to suggest that the cluster that formed the Sun experienced a number of supernova explosions prior to the formation of the Sun. These explosions probably actually triggered the collapse of matter from which the Solar System formed, and the explosion of stars enriched the medium with metals. (That’s where metals come from: other than water and organic materials that contain hydrogen, almost everything we’re made of and that exists around us came from the interiors of stars that blew up and disgorged this stuff back into the interstellar medium… before the Sun and Earth even formed). Supernovas result from very bright, very massive stars that end their lives in spectacular explosions. These still occur, about once a century or so in a Galaxy like the Milky Way, but it’s thought they were more common billions of years ago, when star formation was a bit more ramped up than at present (a lot of the matter has been used up). 

An interesting aside here. While the Sun is unusually rich in metals for a star of its age, stars more recently formed, due to the continual enrichment of the interstellar medium over time, are somewhat more likely to be similarly rich in metals. What this implies is that to the extent that metal richness of the formative medium is a necessary prerequisite for complex life, and intelligent life in particular, we may be pioneers. The universe may be very young from this point of view... complex worlds may just be getting going, and ours is a forerunner. Most of the stars that will ever form in the universe have already formed (another topic!), but it may well be that most of the complex forms of life that may one day evolve have yet to do so. (Good, we'll get on the ground floor of the greatest real estate grab ever!) 

Anyway, the particulars of the cluster that formed the Sun may also account for the presence of comets in the Solar System. There’s a current school of thought that says that comets are not typical of stars in general, but form when there is interaction between stars in close proximity during their formation stage in a relatively (but not extremely) dense cluster. This is important because it’s also now generally thought that the origin of the Earth’s oceans may well have been bombardment by millions and millions of comets, especially early in its history. (Comets are mostly water). If a star more or less like the sun had a rocky world more or less like Earth, but no comets, that world might remain dry and uninhabitable forever.

These characteristics of the formation of the Sun were not unique, but neither were they universal. Most stars of comparable age and brightness are different. They have lower levels of metals, and may well have very different histories and planetary systems. So you can’t blithely assume that earthlike worlds will be common orbiting such stars. They may well not be. On the other hand, there’s no reason to believe that conditions have to be exactly like Earth for complex life to form. A star may be quite a bit dimmer or brighter, and conditions on the planet of life-origin could be rather different. We don’t have a clear picture what the parameters are. Some think that Mars may have had an ocean early in its history, and may have developed some kind of life, although that remains speculative. So it’s at least plausible that conditions could vary quite a bit from what we have here and still result in living worlds.

What are some of the other factors? Robert Brownlee and Peter Ward published a book in 2000 called Rare Earth which discusses a number of factors that they contend make the Earth virtually unique as an abode of complex, multicellular life. (See here). They talk about a ‘galactic habitable zone’ (you need to be the right distance from the center of the Galaxy to have the right kind of stars and no disruptive cosmic events in the necessary time). They talk about the need for a Jupiter like planet to shepherd the colliding asteroids of a forming solar system, and keep a planetary surface relatively impact free for long periods of time (look at the Moon… big impacts were common in the early Solar System). They talk about orbital stability, and reasons to believe it may be more or less fortuitous in our case. They talk about mass and composition of an earthlike planet, which may be more or less coincidental. The Earth, it turns out, formed from the collision of two planets, which then formed the Earth/moon. The presence of the moon may have affected mantle convection, plate tectonics, axial tilt stability, and other factors that may or may not be crucial for complex life. It’s also just not known how likely the origin of life itself is; and how likely some of the other steps in the evolution of a complex biosphere may be. Optimists tend to assume that these things are inevitable, given the right conditions, but we just don’t know. All this may add up to the conclusion, as Brownlee and Ward argue, that while simple unicellular (bacterialike) life may be rather common where temperate liquid-water environments form, complex multicellular life, and intelligent life in particular, may be spectacularly rare in the universe.

Of course, the universe is enormous. There’s at least one such world in the Milky Way (Earth), so it seems inevitable that somewhere out there in the vast sea of galaxies, there are others. But maybe Carl Sagan’s (and others’) assumptions that there were billions of civilizations in our Galaxy alone were, well, wildly overoptimistic. None of this rises to the level of certainty, but it’s a safe bet that the truth is not exactly what people like Sagan thought, although it may also not be quite as bleak as the Rare Earth folks think either.

One factor that is quite puzzling is the way the Earth has maintained a habitable (water liquid) temperature for a long, long time, despite the fact that the Sun, like other stars, has grown brighter during that time. (About 20% since the formation of the oceans). Somehow, atmospheric conditions have changed, possibly in a Gaia-like global feedback system, so as to keep global temperatures relatively stable, within a range where life is possible. How likely is that? No one really knows, but it’s another possible pitfall in the evolution of a stable living world like ours.

So what does this all add up to? If you read or watch science fiction based on the tradition dating back to Buck Rogers, there seems to be a conventional assumption that outer space, (realistically, the stars around us in the galaxy), are teeming with living worlds somewhat like Earth, and that alien intelligent beings are common. But from what we actually know, the Sun is not unique but also has a number of uncommon characteristics; and the formation of the Earth has some unusual circumstances as well. There are reasons to believe that some of the characteristics of the Earth that make it habitable may be rather unlikely to develop. So, I think it’s a pretty reasonable assumption to say that complex life, especially intelligent life, has arisen on Earth through a series of at least somewhat unlikely events, and that worlds similar to Earth, with complex biospheres and intelligent inhabitants, are likely to be relatively rare in the universe, and those that do exist, necessarily, are likely to be not too close to us.

Sobering thoughts, contrary to a sort of unspoken conventional wisdom of the past half century or so, at least among those whose minds have tended to even consider these questions. To me, because life like that on Earth may well be rather unusual and rare, is all the more reason why we, as stewards of the biosphere we have evolved the ability to destroy, must be all the more careful to preserve it and protect its richness and complexity. We are unlikely in any foreseeable future to encounter its like. 


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To anyone who actually read this whole post, I am glad to assure you that follow-on posts will be substantially shorter. Thanks for your interest.

04 January 2010

E-mail to Fox News re Brit Hume's outrageous religious commentary on l'affaire Tiger woods

I exaggerated my real degree of offense a bit, perhaps, in this e-mail to Fox News Sunday regarding the silly and stupid, as well as hateful and bigoted, remarks of Brit Hume urging Buddhist Tiger Woods to convert to Christianity. In reality, I think the man's an idiot and I give his opinions essentially no weight, so it's hard to be genuinely offended by anything he says. What is offensive is that this all-propaganda-all-the-time network exists at all and, its existence a fact, that it gives this blowhard air time. Here is the clip (with Andrew Sullivan's take), for those interested.

As a Buddhist, I was deeply shocked and offended by the increasingly incoherent Brit Hume's outrageous denigration of Buddhism and his shameless proselytizing of his religion, in connection with the essentially trivial and greatly over-emphasized Tiger Woods affair, on the most recent airing of Fox News Sunday.

Opinion is one thing, and is appropriate on an opinion show like
Fox News Sunday, although in my view no opinions regarding Mr. Woods's supposed need for redemption are appropriate or necessary and time spent on this affair on air is time wasted that could be better put to much more pressing matters. But in any case, in this context or any other, to dismiss and openly disrespect one of the world's oldest and most perennial religions in this manner is simply unacceptable, and well beyond the scope of reasonable on-air discourse. Mr. Hume should either apologize on air or be fired. Buddhists are obviously a minority in America, but the notion that this kind of open disregard and denigration is acceptable must be put to rest firmly and immediately.