Tuesday, October 25, 2005

Bird-like dinosaur forces rethink, etc (supporting my Gondwanan origins of birds theory)

Here are science news items (which are getting a bit old now and so some of the links may no longer work) with my comments in square brackets.

Bird-like dinosaur forces rethink, BBC, 13 October 2005 ... A rooster-sized dinosaur with a long, slender snout and wing-like limbs is forcing a rethink on bird evolution. The 90 million-year-old reptile belongs to the same sickle-clawed group of dinosaurs as Velociraptor and feathered dinosaurs from China. Buitreraptor gonzalezorum, from the Neuquén Basin in central Argentina may provide tantalising evidence that powered flight evolved twice. Details of the discovery appear in the academic journal Nature. One theory suggests the lineage of dinosaurs the new animal belonged to, the dromaeosaurs, originated in the Cretaceous Period (144 to 65 million years ago). But this discovery suggests their lineage can be traced further back in time, to the Jurassic (206 to 144 million years ago), experts say. ... It would mean dromaeosaurs were around when the present-day continents of Earth were organised into a single landmass [Pangaea]. This giant landmass later split into northern and southern parts, called Laurasia and Gondwana respectively. Buitreraptor, ... The animal was about the size of a rooster "The preservation of Buitreraptor is superb. The rich fauna of this area, known as La Buitrera, includes other carnivorous dinosaurs," said co-discoverer Sebastián Apesteguía ... Until recently, the dinosaur group had only been found in Cretaceous rocks of Asia and North America, continents that were part of Laurasia. The new discovery, named Buitreraptor, provides definitive evidence that dromaeosaurs also lived in South America - part of Gondwana. They must have originated when all of the continents were still assembled in a single landmass - during the Jurassic. When the landmass split in two, the dromaeosaurs diverged into northern and southern groups. ... Analysis by the authors of the Nature paper show Buitreraptor and Rahonavis, a fossil animal from Madagascar previously considered a primitive bird, form a southern branch of the dromaeosaur family tree. This branch is distinct from Laurasian dromaeosaurids, including Velociraptor and some of the famous feathered dinosaurs from China. Birds are commonly thought to have evolved from this group. The authors say the discovery Rahonavis and Buitreraptor have long and wing-like forelimbs could imply that flight evolved twice, once in birds and once among this group of Gondwanan dromaeosaurs. ... [See also Livescience, San Francisco Chronicle, Science News & Washington Post. This is more evidence for my Gondwanan origins of birds theory (as posted to my now-terminated list CED: 01-Mar-03; 03-Mar-03; 21-Jul-04; 22-Jan -05), and the falsification of the "feathered dinosaurs from China" theory! The basic evidence for the theory is: 1) Rattites (the order of primitive flightless birds including the emu, ostrich, rhea) which T.H. Huxley originally proposed as the link between dinosaurs and birds, have a typical Gondwanan (southern hemisphere) distribution; 2) the other large order of flightless birds, penguins, are found only in the southern hemisphere; 3) it is more parsimonious that flying birds originated among Gondwanan flightless birds, and then some flew north to Laurasia, than that flying birds originated in Laurasia and then some flew south to Gondwana and then all lost the ability to fly.]

Dolphins sing 'Batman' theme, ABC/Discovery News, Jennifer Viegas, 3 October 2005 ... Scientists have taught dolphins to combine both rhythm and vocalisations to produce music, resulting in an extremely high-pitched, short version of the Batman theme song. The findings, outlined in two studies, are the first time that nonhuman mammals have demonstrated they can recognise rhythms and reproduce them vocally. "Humans are sensitive to rhythms embedded in sequences of sounds, but we typically consider this skill to be part of processing for language and music, cognitive domains that we consider to be uniquely human," says Professor Heidi Harley, lead author of both studies. "Clearly, aspects of those domains are available to other species." ... The researchers first had an adult male bottlenose dolphin position itself in front of an underwater sound projector, called a hydrophone, that produced six different 14 kiloherz, 4 second rhythms. The dolphin was rewarded for performing a certain behaviour to each rhythm. For example, when rhythm 1 played, it waved its pectoral fin and when rhythm 2 played, it tossed a ball. The various rhythms were played at different frequencies and tempos to ensure the dolphin was recognising rhythms instead of just frequencies or sound durations. Another adult male was trained to produce similar rhythms using a pneumatic switch, essentially a small, air-filled ball connected to a computer that then generated sounds whenever the dolphin pressed the switch. "The dolphin was reinforced for producing a specific rhythm to a specific object," .... The dolphin spontaneously vocalised to the rhythms, so the researchers started to reward the male with fish whenever it matched its 'singing' to the rhythms. By the end of the studies, the scientists could show an object, such as the Batman doll, which represented a certain rhythm-vocalisation combo to the dolphin, and it would create the correct sounds both vocally and using the switch. .. Gordon Bauer ... says, "This is the first report, to my knowledge, of a nonhuman mammal's ability to discriminate rhythmic patterns." But Bauer doubts that dolphins realise they are producing what people consider 'music'. "I think music is a human construct," he says. "I doubt that it has pertinence to animals, although the elements of music, such as pitch, time, timbre, rhythm, etc, may be incorporated into animal communication." Harley agrees ... [It is refreshing to hear an animal behaviourist acknowledge that while animals may appear to be doing something similar to humans (in this case "to combine both rhythm and vocalisations to produce music") it is not really music in the sense that the animal is just producing sounds without realizing that it is music. I have added this to my "Problems of Evolution" book outline, PE 14.1.7. "Man ... Uniqueness ...Music" ]

Ancient oceans 'filled with sulphur', The Australian, October 06, 2005 ... THE ocean to Australia's north was once filled with toxic sulphur and contained bacteria that may have made the water look purple, new research said. By examining some of the world's best preserved rocks, once under water and now part of land formations near the Gulf of Carpentaria, an Australian scientist has gained a rare glimpse of what the oceans were like 1.6 billion years ago. Dr Jochen Brocks ... found the sea was inhabited by purple and green sulphur-loving organisms which depended on light to live. Scientists have always assumed that as the earth's atmosphere became more oxygenated, so too did the oceans. But they could not explain why, if that was the case, complex forms of life did not become abundant earlier than about 600 million years ago. Dr Brocks' research, published in the latest edition of Nature, provides the first evidence, independent of isotopic findings, that the oceans remained oxygen-starved and sulphur-choked, even while oxygen in the Earth's atmosphere was increasing. In an ancient rock sample from the McArthur Basin in northern Australia, Dr Brocks found molecular remains of green and purple coloured pigments that were used by the bacteria in photosynthesis. Photosynthesis is the process by which plants, algae, and some bacteria harness the energy of sunlight to produce food. Dr Brocks said the presence of the green and purple sulphur bacteria showed the ocean at that time was filled with sulphur close to the surface, where light could penetrate and keep the bacteria alive. "If indeed the oceans were (full of sulphur) during this middle period of earth's history, it would rewrite much of what we've believed about a fifth of the planet's history," Dr Brocks said. "It would seem that this is the reason why the world was ruled by bacteria for such a long time." The new research provides significant clues to the mystery of the other oceans of Earth's "middle age". "Understanding the world's oceans at this time is an important factor in determining why complex forms of life, such as modern algae and animal life, arose so late in the planet's history," Dr Brocks said. The first animal embryos, still mere clusters of cells, only appeared about 600 million years ago. When the oxygenless and toxic waters finally retreated about 800 million years ago, complex eukaryotes, such as algae, finally conquered the world's open oceans, Dr Brocks said. Their development culminated in the Cambrian Explosion 542 million years ago and marked the sudden appearance of most groups of the animals we know today. ... [Sounds like I could have added "sulphur" to the conclusion of the Animal Physiology major assignment that I did on the Cambrian Explosion:

"All of the above? The above proposed explanations for the Cambrian explosion are not mutually exclusive and some, if not all, are complementary and synergistic. The Cambrian radiation of the animal phyla was a unique event in the history of life and was probably the result of a sequence of environmental, ecological and biological interactions, beginning in the Precambrian and working in combination, including: an increase in the amount of atmospheric oxygen; the innovation and elaboration of Hox genes that enabled the development of complex body plans; and ecological niches empty of organisms with that new complexity (Carroll, 1997, p.348; Knoll, & Carroll, 1999). The Cambrian radiation itself may have been triggered by an environmental perturbation near the Proterozoic-Cambrian boundary which was then amplified by intense ecological interactions within new ecosystems (Knoll, & Carroll, 1999)".]

A braney theory, The Economist, Oct 6th 2005 An explanation for the anthropic principle comes a little closer. DID God have a choice? Or, to put the matter less theologically, does the universe have to be the way that it is? The answer to this question, posed by Einstein among others, remains elusive. But it is important, not least because a universe with laws only slightly different from those actually observed would be one in which life-and therefore human life-could never have come into existence. That observation, known as the anthropic principle, disturbs many physicists because they cannot see any fundamental reason why things could not be different. In particular, they cannot see why space has to have three dimensions. But a paper due to be published this month in Physical Review Letters by Andreas Karch ... and Lisa Randall ... suggests that the laws of physics may, indeed, be biased towards three-dimensions. Curiously, though, they have a similar bias towards seven-dimensions. The idea that there may be more dimensions than the familiar ones of length, breadth and height (and also, to be strictly accurate, the fourth dimension of time) is a consequence of attempts to solve an old problem in physics. Ever since Einstein developed his theories of space, time and gravity, physicists have sought a "theory of everything" that would unite those theories with quantum mechanics-the part of physics that describes electromagnetism and the forces that hold atomic nuclei together. ... To date, the best candidates for a theory of everything are various versions of a branch of mathematics called string theory. Unfortunately for common sense, these theories require the universe to have ten or even 11 dimensions rather than the familiar three of space and one of time. To get round this anomaly, some physicists propose that the familiar dimensions are "unfurled", while the other six or seven are rolled up so tightly that they cannot be seen, even with the most powerful instruments available. ... A second interpretation of multidimensionality, however, is that the extra dimensions are not always rolled up, but that even when they are not humans cannot readily observe them because they are not free to move in them. In this version, the space inhabited by humans is a three-dimensional "surface" embedded in a higher dimensional landscape. The particles of which people are composed, and the non-gravitational forces acting on them, are strictly confined to this surface-called a brane (short for membrane)-and, as such, have no direct knowledge of the higher dimensional space around them. Only gravity is free to pervade all parts of the universe, which is one of the reasons why it obeys a different set of rules from the other forces. It is this second interpretation that is invoked by Dr Karch and Dr Randall. They assume that, initially, the universe was filled with equal numbers of branes and anti-branes (the antimatter equivalent of a brane). These branes and anti-branes could take any number of up to ten different dimensions. [They] then demonstrated, mathematically, that a universe filled with equal numbers of branes and anti-branes will naturally come to be dominated by 3-branes and 7-branes because these are the least likely to run into their anti-brane counterparts and thus be annihilated. This result is interesting for two reasons. It is the first piece of work to show that branes alone can explain the existence of hidden dimensions. They do not have to be rolled up to be inaccessible. It is also the first to suggest an underlying preference in the laws of physics for certain sorts of universe, and thus perhaps provide a solution to the anthropic principle. Yet it is not a total solution. Other realities, whether three- or seven-dimensional, could be hidden elsewhere in the landscape. And life in seven-dimensional space would look very different from life on Earth-if, indeed, it existed at all. That is because the force of gravity would diminish far more quickly with distance than it does in this world. As a result, seven-dimensional space could not have planets in stable orbits around stars. Like dark matter and dark energy, therefore, the anthropic principle is still grinning from the sidelines, taunting physicists to explain it. ... [So where did the "universe filled with equal numbers of branes and anti-branes" come from? Or is it branes all the way down?:

"As our ideas developed, a monstrous spectre kept beckoning. Just as the brain of Shakespeare was necessary to produce the famous plays, so prior information was necessary to produce a living cell. But information from where? From some pre-existing life-form, one is tempted to answer, but this would be to incur the ire of Tommy Gold, who tells the following story. A male lecturer had spoken about the nature of the Earth and planets. Afterwards, an old lady came up to him from the audience, claiming she had a theory superior to the one he had described. 'We don't live on a ball revolving around the Sun,' she said, 'we live on a crust of earth on the back of a giant turtle.' Wishing to humour the old lady the lecturer asked, 'And what does this turtle stand on?' 'On the back of a second, still larger turtle,' was the confident answer. 'But what holds up the second turtle?' the lecturer persisted, now in a slightly exasperated tone. 'It's no use, mister,' the old woman replied, 'it's turtles all the way down.' Which epitomizes the conundrum of life. So long as living cells come from pre-existing cells we are calling on support from another turtle. The issue is where do the turtles stop? The conventional answer is that the turtle pile floats on a sea of organic soup, an answer as scientifically improbable as Tommy Gold's story makes it sound." (Hoyle F. & Wickramasinghe C., "Evolution from Space," [1981], Paladin: London, 1983, reprint, pp.164-165)

See tagline for a long, humorous dialogue-style, but helpful (at least to me) quote by the mathematician Ian Stewart on branes and string theory in his book Flatterland (an update on Edwin Abbott's mathematical fiction book Flatland). I found it interesting that string theory has settled on a 10-dimension space-time and that is 3+7.]

Stephen E. Jones, BSc (Biol).
"Problems of Evolution"

"So what ... do you think we are missing? What would tie the whole picture together? That's right. String. `Superstring, actually,' said the Space Hopper. `If you want to bring gravity into the scheme of things, you can't keep the Standard Model exactly as it is. You have to be prepared to modify it a little. ... but that "little" includes a complete rethink of the structure of spacetime. Not just a supersymmetric add-on. Something more significant than that.' It seemed to Vikki that this was going Over The Top. `Why does spacetime have to change, Hopper?' 'Because when you try to quantize gravity, it turns out that particles can't actually remain particles. That just doesn't work - pointlike objects just don't fit all the requirements. So they have to be replaced by something else.' `What?' 'Like I said: superstrings.' `Yes, I know that's what you said, but it made no sense then and it doesn't make any more now!' The Space Hopper gave the criticism due consideration. `Very well,' he said. `A particle is a point or, at least, it looks like a point, with no internal structure. It's a pointlike object, yes?' 'Sure. `Moving up in dimensions, you could replace a pointlike particle by a curve - a string. ... So what happens to quantum strings without ends?' 'They loop round and form a closed loop. A topological circle.' `Ah.' `That's most of them, actually.' `Tidier that way. Otherwise the ends would flap around.' `They can, in some string theories. Anyway, curves are intrinsically one-dimensional. The next step up from curves leads to two-dimensional surfaces membranes. Perhaps with exotic topologies, like Moobius, or the Projective Plain, or a doughnut.' ... `Beyond membranes,' the Space Hopper said ... `are three-dimensional analogues of surfaces, which the Planiturthian physicists insist on calling 3-branes. And then come 4-branes, 5-branes and so on. They also insist on using the symbol p for an arbitrary number of dimensions, rather than the customary N ... and I think I know why. Guess what you get in dimension p?' 'Oh no! p-branes?' 'Absolutely.' `So a surface is a 2- brane?' 'Yes.' `And a string is a 1-brane?' 'Naturally.' `Which makes an ordinary particle, with dimension zero, into a no-brane?' 'I had a feeling that's where you were headed', said the Space Hopper. `You said "superstrings",' Vikki remembered. `You've only explained strings.' `Well, you remember that particles - no-branes in your terminology - are accompanied by ghost extensions into superspace?' `Yes. You mean superstrings are strings that extend into superspace as well as ordinary space?' 'Correct. It's quantum string, it can do that.' `Quantum things can do anything you want, it seems to me. Where do you find these superstrings? At a superstationers?' 'In yet another extension of ordinary space, Vikki. Good job I updated the VUE's HyperZoom facility. .... Follow me!' And down they went, into the smallest scales of the Planiturthian universe - into a world where an electron was too huge to contemplate, where its component quarks glistened like tiny jewelled specks. `Right now we're at the limits of the VUE's spatial resolution,' said the Space Hopper. `Down at the Planck length, where quantum effects make space so fuzzy that it's not even clear that space really exists at all.' `It's frothy,' said Vikki, `not fuzzy.' `That's quantum foam - particles springing into and out of existence, creating space and time along with themselves. Try some, it's quite tasty.' `No thanks!' `Go on. It's a bit like chicken.' `I'm not hungry.' `Suit yourself. See those bright specks?' 'Yes. They're quarks, aren't they?' 'Among other things, yes. What do they look like on this scale?' 'Dots. Points. Nobranes' `Yes. And yet, those points have to support all sorts of quantum states. Spin, charge ... would there be room for such diversity on a no-brane?' That thought hadn't occurred to Vikki before. 'In what sense?' she asked, cagily. `All will shortly become clear. I'll use the HyperZoom to improve the resolution in any other dimensions that may be around-' 'Like superspace?' 'Yes, but there might be others - there's more to a particle than its spin, you know. Ah, yes ... coming into focus now ... Look at that!' 'It's - hey, that quark's not a point at all! It's a tiny loop!' `Yes.' 'And ... isn't it vibrating?' `A little bit, maybe. This one's in its ground state, lowest energy. But if I give it a-' TWANGGGGGGGG! `-then something really interesting happens. Zoom out for a moment, and you'll see.' `Oh. It's changed colour!' `Yes. That's the VUE's way of showing us that it's actually become a different particle altogether. A much more massive relative of a standard quark, as it happens. Doesn't have a name. Anyway, the main thing here is that anything from a 1-brane up can vibrate in all sorts of different ways, whereas a no-brane can't. That means that a 1- brane or a 2-brane or a 3-brane or a zillion-brane can easily support all sorts of different quantum states. Whereas for your traditional point particle the states are just some kind of unexplained add-on. `So here's the idea. On really small scales, spacetime isn't 4D at all. What looks like a tiny point in 4D spacetime is really something else - some kind of p-braned topological hypersurface in a higher-dimensional space.' `How many? Dimensions, I mean? Equal to p?' 'No, could be bigger. For a while 7D and 22D were hot favourites, making the revised spacetime come to 11D or 26D. Right now, though, the consensus is settling on 6D for the extra dimensions - a total of 10D altogether.' `Spacetime is really ten-dimensional?' `That's what every well-informed Planiturthian thinks right now.' `You mean there's a choice?' The Space Hopper laughed. `Oh, yes! A huge choice. The range of n-dimensional spaces is inexhaustible! The problem, Vikki dear, is cutting that number down enough to be able to fix the exact one. Not just the value of n the number of dimensions - but the topological shape of the corresponding space.' `Put that way, I see the difficulty. So how do they sort out all those possibilities?' `Still working on it. But they're making progress. Turned out that the original 11D model - supergravity, it was called - had a fatal flaw. It couldn't encompass the broken symmetry of the weak nuclear force. A People called Edwitten pointed that out in 1984, by their calendar. The way to deal with that was to reduce the dimensionality to 10D. `Now, when you do quantum theoretic calculations, as often as not you get stupid answers.' ... `Easy to make mistakes?' 'No, even when they get the calculations right, they still get stupid answers. Infinity, usually.' `That's bad?' 'It's nonsense. When a physical theory gives you infinity as an answer, it's always a sign of trouble. The real universe doesn't have infinities.' `Hang on, Hopper - we went to infinity in the Projective Plain.' `Yes, but that wasn't a real universe, OK?' `Only an idealization, that's true.' `And in a sense Infinityville wasn't a real infinity, either. But you're distracting me. There is a way to get round these quantum infinities, and it's called renormalization. Doesn't matter exactly what it is - just take my word that it's not an easy trick to pull off. So most potential superstring theories don't work because they're not renormalizable. It turned out that for a 10D superstring theory to be renormalizable it has to be one of five competing possibilities. These are known by their symmetries. One is called SO(32), another is E8 x E8, and they both have an extra 16 dimensions of `internal' states, as well as the 10D of the string itself. See? 26D in all. And the other three are known as Type I, Type IIA, and Type IIB.' 'Imaginative terminology.' `Very. The fascinating thing - a strong hint that such theories could unify gravity and quantum theory, the physicists' Holy Grail - was that they all predicted the occurrence of a particle with spin 2 and mass 0. In quantum theory by itself, that would have been an embarrassment because no such particles are known. But-' `The graviton, if it exists, has to be a particle with spin 2 and mass 0!' yelled Vikki, caught up in the excitement. 'Precisely. String theory seemed to be telling physicists that if they wanted an effective theory of quantum particles, then gravity would be a necessary consequence. All consistent string theories include gravitons.' `It would have been more satisfactory if only some had,' said Vikki. 'To help pick the right one.' `True. But it didn't work out that way ... and it may not be necessary. You see, that People named Edwitten has recently discovered that all five superstring theories fit into a bigger 11D picture, known as M-theory.' The Space Hopper noticed Vikki hopping up and down. `Yes, Vikki, I agree - that's a very imaginative name too, isn't it? But back to my story. There are five different ways to shrink away one of the 11 dimensions of M-theory, and they lead to those five 10D superstring theories. So all five competing theories are actually part of the same Big Picture. Maybe it's the Big Picture that really matters.' He paused. `There's only one problem with all this stuff', he said. `Which is a pity, because it's so beautiful.' `What's the problem with it?' 'It may not be true,' said the Space Hopper sadly. `There's no experimental evidence, you see,' he explained. `Hard to come by desperately hard to come by. For that matter, the calculations are so difficult that there aren't many theoretical predictions, either. So there's precious little to experiment on.' `But couldn't the Planiturthians tell if they really lived in a 10D universe?' 'Couldn't the Flatlanders tell that their 2D world was really just part of 3D Spaceland?' 'Touche. Even so, surely there are experiments that would reveal a whole six extra dimensions? For that matter, why didn't they notice them ages ago?' 'Because, Vikki, they didn't have a HyperZoom. Think about a sheet of paper. What's its dimensionality?' `Two.' `Really?' `Oh. In Flatland, yes. In Spaceland, say, it would really be 3D, but very thin along the third dimension.' `Quite. And the Planiturthian universe looks like a 4D spacetime, but in Superstring Territory it is really 10D, but very thin along the fifth, sixth, seventh, eighth, ninth, and tenth dimensions.' `So thin that the Planiturthians didn't notice?' 'So thin, Vikki, that the Planiturthians can't notice. The structure is below the Planck length - the smallest size their instruments can detect. `That's a pity. Convenient for the theorists, though.' `Suspiciously so. But there might be other ways to find out whether they're right. Indirect ones. For instance, in M-theory there is a class of branes called Dirichlet branes, because they look rather like a surface discovered long before by a People named Peterdirichlet. They turn out to be black branes - branes from which light can't escape. You can even interpret a superstring with ends as a superstring that forms a closed loop, part of which is covered by a black brane. And by doing that, you can reformulate black holes in terms of intersecting black branes wrapped round inside a 7D space.' `And what good does all that do?' asked Vikki. `It makes very accurate predictions about evaporating black holes. But that kind of evidence is just circumstantial. So right now, all anyone can really do is point to the elegance of the theory, and the beautiful way in which it unifies Relativity and quantum theory.' `Which makes it right?' `Not at all. Lots of physicists don't like that approach. They say that beauty could be totally irrelevant. And there are lots of other possibilities in the Mathiverse that don't roll up the extra dimensions of spacetime into very tiny shapes, and there are all sorts of other reasons why the Planiturthians wouldn't notice them, either ... Beauty can be a trap, Vikki. `Anyway, everything in the Mathiverse is beautiful, if you get used to it.' The Space Hopper's U faded momentarily, then renewed itself in a dazzling display of teeth. `None the less, the idea that the extra dimensions are curled up really tightly, so you can observe them only on the extraordinarily small scale of the Planck length, is still the most appealing explanation of why Planiturthians don't observe ten dimensions.' He paused. For once, the bouncy creature seemed at a loss for words. `Um - you know something?' `What?' 'Back in Flatland, Vikki, it's the eve of a new century. Your tour of the Mathiverse has reached its climax. You've learned as much as I can teach you and as much as your brain can digest at one sitting ... I think it's time I took you home. Don't you?' ... Vikki wanted to ask one last question, to make sure she'd understood the essence of the Planiturthian universe. 'You're saying that when the extra dimensions of spacetime get so thin that they're only one Planck length across, they become undetectable?' 'That's right.' `So the only features of the universe that Planiturthians can observe are those that are ... as thick as two short Plancks?' 'You have it exactly,' declared the Space Hopper." (Stewart I., "Flatterland: Like Flatland, Only More So," Macmillan: London, 2001, pp.280-287. Emphasis original)

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