Archive for the ‘astronomy’ Category
Einstein, science and the natural world: a rabid discourse
Einstein around 1915
Canto: Well, we’re celebrating this month what is surely the greatest achievement by a single person in the history of science, the general theory of relativity. I thought it might be a good time to reflect on that achievement, on science generally, and on the impetus that drives us to explore and understand as fully as possible the world around us.
Jacinta: The world that made us.
Canto: Précisément.
Jacinta: Well, first can I speak of Einstein as a political animal, because that has influenced me, or rather, his political views seem to chime with mine. He’s been described as a supra-nationalist, which to me is a kind of political humanism. We’re moving very gradually towards this supra-nationalism, with the European Union, the African Union, and various intergovernmental and international organisations whose goals are largely political. Einstein also saw the intellectual venture that is science as an international community venture, science as an international language, and an international community undertaking. And with the development of nuclear weapons, which clearly troubled him very deeply, he recognised more forcefully than ever the need for us to take international responsibility for our rapidly developing and potentially world-threatening technology. In his day it was nuclear weapons. Today, they’re still a threat – you’ll never get that genie back in the bottle – but there are so many other threats posed by a whole range of technologies, and we need to recognise them, inform ourselves about them, and co-operate to reduce the harm, and where possible find less destructive but still effective alternatives.
Canto: A great little speech Jas, suitable for the UN general assembly…
Jacinta: That great sinkhole of fine and fruitless speeches. So let’s get back to general relativity, what marks it off from special relativity?
Canto: Well I’m not a physicist, and I’m certainly no mathematician, but broadly speaking, general relativity is a theory of gravity. Basically, after developing special relativity, which dealt with the concepts of space and time, in 1905, he felt that he needed a more comprehensive relativistic theory incorporating gravity.
Jacinta: But hang on, was there really anything wrong with space and time before he got his hands on them? Why couldn’t he leave them alone?
Canto: OMG, you’re taking me right back to basics, aren’t you? If I had world enough, and time…
Jacinta: Actually the special theory was essentially an attempt – monumentally successful – to square Maxwell’s electromagnetism equations with the laws of Newton, a squaring up which involved enormous consequences for our understanding of space and time, which have ever since been connected in the concept – well, more than a concept, since it has been verified to the utmost – of the fourth, spacetime, dimension.
Canto: Well done, and there were other vital implications too, as expressed in E = mc², equivalating mass and energy.
Jacinta: Is that a word?
Canto: It is now.
Jacinta: So when can we stop pretending that we understand any of this shite?
Canto: Not for a while yet. The relevance of relativity goes back to Galileo and Newton. It all has to do with frames of reference. At the turn of the century, when Einstein was starting to really focus on this stuff, there was a lot of controversy about whether ‘ether’ existed – a postulated quasi-magical invisible medium through which electromagnetic and light waves propagated. This ether was supposed to provide an absolute frame of reference, but it had some contradictory properties, and seemed designed to explain away some intractable problems of physics. In any case, some important experimental work effectively quashed the ether hypothesis, and Einstein sought to reconcile the problems by deriving special relativity from two essential postulates, constant light speed and a ‘principle of relativity’, under which physical laws are the same regardless of the inertial frame of reference.
the general theory – get it?
Jacinta: What do you mean, ‘the initial frame of reference’?
Canto: No, I said ‘the inertial frame of reference’. That’s one that describes all parameters homogenously, in such a way that any such frame is in a constant motion with respect to other such frames. But I won’t go into the mathematics of it all here.
Jacinta: As if you could.
Canto: Okay. Okay. I won’t go any further in trying to elucidate Einstein’s work, to myself, you or anyone else. At the end of it all I wanted to celebrate the heart of Einstein’s genius, which I think represents the best and most exciting element in our civilisation.
Jacinta: Drumroll. Now, expose this heart to us.
Canto: Well we’ve barely touched on the general theory, but what Einstein’s work on gravity teaches us is that by not leaving things well alone, as you put it, we can make enormous strides. Of course it took insight, hard work, and a full and deep understanding of the issues at stake, and of the work that had already been done to resolve those issues. And I don’t think Einstein was intending to be a revolutionary. He was simply exercised by the problems posed in trying to understand, dare I say, the very nature of reality. And he rose to that challenge and transformed our understanding of reality more than any other person in human history. It’s unlikely that anything so transformative will ever come again – from the mind of a single human being.
Jacinta: Yes it’s an interesting point, and it takes a particular development of culture to allow that kind of transformative thinking. It took Europe centuries to emerge from a sort of hegemony of dogmatism and orthodoxy. During the so-called dark ages, when warfare was an everyday phenomenon, and later too, right through to the Thirty Years War and beyond, one thing that could never be disputed amongst all that disputation was that the Bible was the word of God. Nowadays, few people believe that, and that’s a positive development in the evolution of culture. It frees us to look at morality from a broader, richer, extra-Biblical perspective..
Canto: Yes we no longer have to even pretend that our morality comes from such sources.
Jacinta: Yes and I’m thinking of other parts of the world that are locked in to this submissive way of thinking. A teaching colleague, an otherwise very liberal Moslem, told me the other day that he didn’t believe in gay marriage, because the Qu-ran laid down the law on homosexuals, and the Qu-ran, because written by God, is perfect. Of course I had to call BS on that, which made me quite sad, because I get on very well with him, on a professional and personal basis. It just highlights to me the crushing nature of culture, how it blinds even the best people to the nature of reality.
Canto: Not being capable of questioning, not even being aware of that incapability, that seems to me the most horrible blight, and yet as you say, it wasn’t so long ago that our forebears weren’t capable of questioning the legitimacy of Christianity’s ‘sacred texts’, in spite of interpreting those remarkably fluid texts in myriad ways.
Jacinta: And yet out of that bound-in world, modern science had its birth. Some modern atheists might claim the likes of Galileo and Francis Bacon as one of their own, but none of our scientific pioneers were atheists in the modern sense. Yet the principles they laid down led inevitably to the questioning of sacred texts and the gods described in them.
Canto: Of course, and the phenomenal success of the tightened epistemology that has produced the scientific and technological revolution we’re enjoying now, with exoplanets abounding, and the revelations of Homo floresiensis, Homo naledi and the Denisovan hominin, and our unique microbiome, and recent work on the interoreceptive tract leading to to the anterior insular cortex, and so on and on and on, and the constant shaking up of old certainties and opening up of new pathways, all happening at a giddying accelerating rate, all of this leaves the ‘certainty of faith’ looking embarrassingly silly and feeble.
Jacinta: And you know why ‘I fucking love science’, to steal someone else’s great line? It’s not because of science itself, that’s only a means. It’s what it reveals about our world that’s amazing. It’s the world of stuff – animate and inanimate – that’s amazing. The fact that this solid table we’re sitting at is made of mostly empty space – a solidity consisting entirely of electrochemical bonds, if that’s the right term, between particles we can’t see but whose existence has been proven a zillion times over, and the fact that as we sit here on a still, springtime day, with a slight breeze tickling our faces, we’re completely oblivious of the fact that we hurtling around on the surface of this earth, making a full circle every 24 hours, at a speed of nearly 1700 kms per hour. And at the same time we’re revolving around the sun at a far greater speed, 100,000 kms per hour. And not only that, we’re in a solar system that’s spinning around in the outer regions of our galaxy at around 800,000 kilometres an hour. And not only that… well, we don’t feel an effing thing. It’s the counter-intuitive facts about the natural world that our current methods of investigation reveal – these are just mind-blowing. And if your mind doesn’t get blown by it, then you haven’t a mind worth blowing.
Canto: And we have two metres of DNA packed into each nucleus of the trillions of cells in our body. Who’d’ve thunkit?
whatever
exoplanets – an introduction of sorts
Jacinta: So do you think we’ve hauled ourselves out of ignorance sufficiently to have a halfway stimulating discussion on exoplanets?
Canto: I think we should try, since it’s one of the most exciting and rapidly developing fields of inquiry at the moment.
Jacinta: And that’s saying something, what with microbiomes, homo naledi, nanobots and quantum biology…
Canto: Yes, enough to keep us chatting semi-ignorantly to the end of days. But let’s try to enlighten each other on exoplanets…
Jacinta: Extra solar planets, planets orbiting other stars, the first of which was discovered just over 20 years ago, and now, thanks largely to the Kepler Space Observatory, we’ve discovered thousands, and future missions, using TESS and the James Webb telescope, will uncover megatonnes more.
Canto: Yes, and you know, about the Kepler scope, l was blown away – this might be veering off topic a bit, but I was blown away in researching this by the fact that Kepler orbits the sun. I mean, I knew it was a space telescope, but I just assumed it was in orbit around earth, probably at a great distance to avoid interference from our atmosphere, but that we can position satellites in orbit around the sun, that really sort of stunned me, more I think than the exoplanet discoveries. Am I being naive?
Jacinta: No, not at all. Well, yes and no. Everything is stunning if you haven’t followed the incremental steps along the knowledge pathway. I mean, if you think, hey the sun’s a way away, and it’s really big and dangerous, best not go there, or something like that, you might be shocked, but think about it, we’ve been sending satellites around the earth for a long time now, and we know how to do it because we know about earth’s gravitational field and can calculate precisely how to harness it for satellite navigation. We’ve currently got a couple of thousand human-made satellites orbiting the earth and trying more or less successfully to avoid colliding with each other. So the sun also has a gravitational field and we’ve known the mathematics of gravitational fields since Newton. It’s the same formula for a star, a planet or whatever, all you need to know is its mass and its radius. And look at all the natural objects orbiting the sun without a problem. Can’t be that hard.
Canto: Okay… so how do we know the mass of the sun? Okay, forget it, let’s get back to exoplanets. What’s the big fuss here? Why are we so dead keen on exploring exoplanets?
Jacinta: Well the most obvious reason for the fuss is SETI, the search for extra-terrestrial intelligence, but to me it’s just satisfying a general curiosity, or you might say a many-faceted curiosity. And it’s all about us mostly. For example, is the solar system that we inhabit typical? We’ve mostly thought it was but we didn’t have anything to compare it with, but now we’re discovering all sorts of weird and wonderful planetary systems, and star systems, with gas giants like Jupiter orbiting incredibly close to their stars – it’s completely overturned our understanding of how planets exist and are formed, and that’s fantastically exciting.
Canto: So you say we discovered the first exoplanet about 20 years ago, and now we know about thousands – that’s a pretty huge expansion of our knowledge, so how come things have changed so fast? You’ve mentioned new technologies, new space probes, why have they suddenly become so successful?
Jacinta: Well I suppose it’s been a convergence of developments, but let’s go back to that first discovery, back in 1992. Two planets, the first ever discovered, were found orbiting a pulsar – a rapidly rotating neutron star. First discovery, first surprise. Pulsars with planets orbiting them, who would’ve thought? Pulsars are the remnants of supernovae – how could planets have survived that? But that first discovery was largely a consequence of our ability to measure, and the fact that pulsars pulse with extreme regularity. Any anomaly in the pulsing would be cause for further investigation, and that’s how the planets were found, and later independently confirmed. Now this was big news, in a field that was already becoming alert to the possibility of exoplanets, so you could say it opened the floodgates.
Canto: Really? But they didn’t discover any more for two or three years.
Jacinta: Well, okay it opened the gates but it didn’t start the flood, that really happened with the second discovery, the first discovery of a planet orbiting a main-sequence star like ours.
Canto: Main sequence? Please explain?
Jacinta: Well these are stars in a stable state, a state of balance or equilibrium, fusioning hydrogen – basically stars not too different from our own, within much the same range in terms of mass and luminosity. So 51 pegasus b was the first planet to be discovered by the radial velocity method, and radial velocity means the speed at which a star is moving towards or away from us. We can measure this, and whether the star is accelerating or decelerating in its movement, by means of the Doppler effect – waves bunch up when the object emitting them is moving towards us, they spread out when the object is receding from us, and the degree of the bunching or the spreading is a measure of their speed and whether it’s accelerating or decelerating. Now we can measure this with extreme accuracy using spectrometers, and that includes any perturbations in the star’s movement caused by orbiting bodies. That’s how 51 pegasus b was discovered.
Canto: So… how long have we had these spectrometers? Were they first developed in the nineties, or to the level of accuracy that they could detect these perturbations?
Jacinta: Well I don’t have a precise answer to that apart from the general observation that spectroscopes are getting better, and more carefully targeted for specific purposes. The French ELODIE spectrograph, for example, which was used to find 51 pegasus b, was first deployed in 1993 specifically for exoplanet searching, and since then it’s been replaced by another improved instrument, but of the same type. So it’s a kind of non-vicious circle, research leads to new technology which leads to new research and so on.
Canto: So – we’ve gotten very good at measuring perturbations in a star’s regular movements…
Jacinta: Regular perturbations.
Canto: And we know somehow that these are caused by planets orbiting around them? How do we know this?
Jacinta: Well we will know from the size of the perturbation and its regularity that it’s an orbiting body, and we know it’s not a star because it’s not emitting any light (though it may be a low-mass star whose light isn’t easily separated from its parent star). We also know – we knew from the results that it was a massive planet orbiting very close to its star – a hot Jupiter as they call it. And that was another surprise, but we’ve developed different techniques for discovering these things and we often use them to back each other up, to confirm or disconfirm previous findings. The ELODIE observation of 51 pegasus b was confirmed within a week of its announcement by another instrument, the Hamilton spectrograph in California. So there’s a lot of confirmation going on to weed out false positives.
Canto: So radial velocity is one technique, and obviously a very successful one as it got everyone excited about exoplanets, but what others are there, and which are the most successful and promising?
Jacinta: Well the radial velocity method was initially the most successful as you say, and hundreds of exoplanets have been discovered that way, but this method actually led to a kind of bias in the findings, because it was only able to detect perturbations above a certain level, so it was best for finding large planets close to their stars. But of course that was good too because we had never imagined that large gassy planets could exist so close to their stars. It’s opened up the whole field of planet formation. Then again, if the main aim is to find earth-like planets, this method is less effective than other methods. So let’s move on to the Kepler project. Kepler was launched in 2009, and since then you could say it has blitzed the field in terms of exoplanet detection. It uses transit photometry, which means that it measures the dimming of the light from a star when an orbiting planet passes between it and the Kepler detector.
Canto: So I get the idea of transit, as in the transit of venus, which we can see pretty clearly, but it’s amazing that we can detect transiting planets attached to stars so many light years away.
Jacinta: Well this is how we’ve expanded our world, from the infinitesimally small to the unfathomably large, from multiple billions of years to femtoseconds and beyond, through continuously refining technology, but let’s get back to Kepler. It orbits around the sun, and has collected data from around 145,000 main sequence stars in a fixed field of view – stars that are generally around the same distance from that dirty big black hole at the centre of our galaxy as our sun is.
Canto: Is that significant – that we’re focusing on stars in that range?
Jacinta: Apparently so, at least according to the Rare Earth Hypothesis, which puts all sorts of unimaginative limits on the likelihood of earth-like planets, IMHO, but no matter, it’s still a vast selection of stars, and we’ve reaped a grand harvest of planets from them – some 3000-odd, with over 1000 confirmed.
Canto: So… promising earth-like planets?
Jacinta: Yes, but I must point out that earth-like planets are difficult to detect. You see, Kepler was a kind of experiment, and we’ve learned from it, so that our next project will be much improved. For various reasons due to the photometric precision of the instrument, and inaccurate estimates of the variability of the stars in the field of view, we found that we needed to observe more transits to be sure we’d detected something. In other words we needed a longer mission than we’d planned for. And of course, Kepler has suffered serious technical problems, especially the failure of two reaction wheels, which have affected our ability to repoint the instrument. Having said that, we’ve been more than happy with its success.
Canto: Okay I just want to talk about these exoplanets. Can you summarise the most interesting discoveries?
Jacinta: Well, Kepler has certainly corrected the view we might’ve gotten from the earlier radial velocity method that large Jupiter-like planets are more common than smaller ones. We’ve had a number of reports from the Kepler group over the years, and over time they’ve adjusted downwards the average mass of the planets detected. And yes, they’ve discovered a number of planets in the ‘habzone’ as they call it. But that’s not all – only this year NASA confirmed the existence of five rocky planets, smaller than earth, orbiting a star that’s over 11 billion years old. I’m just trying to give you an idea of the explosion of findings, whether or not these planets contain life. And we’ve only just begun our hunt, and the refinement of instruments. It’s surely a great time to study astrophysics. It’s not just SETI, it’s about the incredible diversity of star systems, and working out where we fit into all this diversity.
Canto: Okay, I can see this an appropriately massive subject. Maybe we can revisit it from time to time?
Jacinta: Absolutely.
Some very useful sites:
http://www.planetary.org/explore/space-topics/exoplanets/
https://en.wikipedia.org/wiki/Kepler_(spacecraft)
how did life begin?: part 2 – RNA, panspermia, viroids and reviving the blob
Jacinta: So you’re going to talk about RNA, I know that stands for ribonucleic acid, and DNA is deoxy-ribonucleic acid, so – RNA is DNA without the oxygen?
Canto: Uhhh, you mean DNA is RNA without the oxygen.
Jacinta: Whatever, they’re big complex molecules aren’t they, but RNA is simpler, and less stable I think.
Canto: Okay, I’ll take it from here. We haven’t really known for very long that DNA is the essential material for coding and replicating life, and it’s a very complex molecule made up of four chemical bases, adenine, guanine, thymine and cytosine, better known as A, G, T and C. They connect to form base pairs, A always pairing with T and C with G.
Jacinta: What the hell are chemical bases? Do you mean bases as opposed to acids?
Canto: Well, yes. These bases, also called nucleobases, accept hydrogen ions, which have a positive charge. It’s all about pair bonding. The nucleobases – A, G, C and T, as well as uracil, found in RNA – are nitrogen-containing compounds which are attached to sugars… but let’s not get bogged down too much. The point is that DNA and RNA are nucleic acids that code for life, and most of the researchers chasing down the origin of life believe that RNA is a precursor of DNA in the process of replication.
Jacinta: And presumably there are precursors to RNA and so on.
Canto: Well presumably, but let’s just look at RNA, because we have a fair amount of evidence that this molecule preceded DNA as a ‘life-engine’, so to speak, and really no solid evidence, that I know of, of anything before RNA.
Jacinta: Okay so what is this evidence, and why did DNA take over?
Canto: Right, now the subject we’re entering into here is abiogenesis, the process by which life emerged from the inanimate. RNA is probably well down the chain from this emergence, but better to start with it than to dive into speculation. Now as you probably know, RNA has a single helical structure, and today it’s heavily involved in the process whereby DNA ‘creates’ proteins. In fact, all current life forms involve the action and interaction of three types of macromolecule, DNA, RNA and proteins…
Jacinta: But of course these complex molecules didn’t spring from nowhere.
Canto: Well we don’t know how they were built up, and many pundits think they may have been seeded here from elsewhere during the late heavy bombardment, which came to an end about 3.8 billion years ago, around the time that those Greenland rocks, with their heavy load of organic carbon, have been dated to. It seems plausible considering how quickly life seems to have taken off here.
Jacinta: Okay so tell us about RNA, how does it relate to the other two macromolecules?
Canto: Well, RNA is able to store genetic information, like DNA, and in fact it’s the genetic material for some of our scariest viruses, such as ebola, SARS, hep C, polio – not to mention influenza.
Jacinta: Wow, I didn’t know that. But one thing I do know about viruses is that they can’t exist independently of a host, so is RNA the basis of any truly independent life forms?
Canto: Not currently, on our planet, as far as we know, but the evidence is fairly strong that RNA has been central to life here from the very beginning, as it is still key to the most basic components of cells such as ribosomes, ATP and other co-enzymes. This suggests that RNA was once even more central, but in some areas it’s been subordinated to, and harnessed to, the more complex and recent DNA molecule. But, yes, since we can’t look at RNA coding for independent life-forms, we need to wind the clock back still further to look at precursors and other constituents of life, such as amino acids and peptides.
Jacinta: Which are chemical molecules, not biological ones. It seems to me we’re still a long way from working out the leap from chemistry to biology.
a peptide or amide bond – a covalent bond between two amino acid molecules
Canto: Yes, yes but we’re bridging various gaps. Peptides are created from amino acids, as you know. They are chains of amino acids linked by peptide bonds, and proteins are only distinguished from peptides in that they’re bigger versions of them, and bonded in a particular biologically useful way. You’ll notice when you read about this stuff that the terms ‘chemistry’ and ‘biology’ are used rather arbitrarily – a chemical compound can be referred to as a biological compound and vice versa. But various experiments have cast light on how increasingly ‘biological’ constituents are formed from simpler elements. For example, you may know that meteorites and comets, which bombarded the early earth in great numbers, contained plenty of amino acids – we’ve counted more than 70 different amino acids derived from meteorites, such as the Murchison meteorite that landed in Victoria in 1969. Another probable source of these amino acids, and even more complex and ‘biological’ molecules is comets, which also contain a lot of water in frozen form, but this has raised the question of how these molecules could have survived the impact of these colossal objects, which released enormous energy, some of them partially vaporising the earth’s crust. But an ingenious experiment, described in this video, and elsewhere, was able to simulate a comet’s impact, creating pressures many times greater than that experienced in our deepest oceans, to see what would happen to the amino acids. It was expected that they would barely survive the impact, but surprisingly they not only survived but forged bonds that created complex peptides.
a fragment of Murchison meteorite – of which there are many. This carbonaceous chondrite is still being analysed for organic compounds. Up to 70 amino acids identified so far
Jacinta: Mmmm, that is interesting. So, the gap between peptides, or proteins, and RNA, what do we know about that?
Canto: Well, now you’re getting into highly speculative territory, but it’s certainly worth speculating about. Firstly, though, in trying to solve this origin of life problem, we have to note that the earth’s atmosphere was incredibly different from what it is now. In fact it was probably quite different from the way Haldane and Oparin and later Miller and Urey envisaged it. It was predominantly carbon dioxide, with hydrogen sulphide, methane and other unpleasant gases – unpleasant to us, that is. That, together with the continual bombardment from outer space has led some scientists to suggest that the place to find the earliest life forms isn’t the open surface but in hidden nooks and crannies or deep underground, in more protected environments.
Jacinta: Yeah the discoveries of so-called extremophiles has made that idea fashionable, no doubt, but presumably these extremophiles are all DNA-based, so I don’t see how investigating them will answer my question.
Canto: Okay, so it’s back to RNA. The thing is, I don’t want to go into the properties of RNA here, it’s just too complicated.
Jacinta: I believe it was Richard Feynman who said something like ‘to fully understand a thing you have to build it’. So there’s still this leap from polypeptides or proteins, which don’t code for anything, they’re just built by ribosomes – RNA structures – from DNA instructions, to sophisticated coded replicators. We have no idea how DNA or RNA came into being, and nobody has successfully created life apart from Doktor Frankenstein. So it’s all a bit disappointing.
Canto: You must surely be joking, or just playing devil’s advocate. You know very well that this is an incredibly difficult nut to crack, and we’ve made huge progress, new discoveries are being made all the time in this field.
Jacinta: Okay, impress me.
Canto: Well, only this year NASA scientists have reported that the nucleobases uracil, thymine and cytosine, essential ingredients of DNA and RNA, have been created in the laboratory, from ingredients found only in outer space – for example pyramidine, which they’ve hypothesised was first created in giant red stars – and they’ve found pyrimidine in meteors. So, another step towards creating life, and further evidence that life here may have been seeded from elsewhere. And if that doesn’t impress you, what about viroids?
Jacinta: Uhhh… what are they, viral androids? Which reminds me, what about the artificial intelligence route to creating life? Intelligent life, what’s more exciting.
Canto: Another time. Viroids are described as ‘sub viral pathogens’. We were talking about viruses before, as a kind of halfway house between the living and the lifeless, but really they’re much more on the side of the living. The smallest known pathogenic virus is over 2000 nucleobases long, and the biggest – well, a megavirus was famously identified just last year and revived after being frozen in Siberian permafrost for something like 35,000 years…
Jacinta: An ancient megavirus has been revived…? WTF? Who thought that was a great idea? Wait a minute, the Siberian permafrost, wasn’t that where Steve MacQueen and his mates dropped The Blob? Megadeath, not just a shite band! We’re doomed!
Canto: Well, strictly speaking it’s a virion, a virus without a host, which means it’s in a kind of dormant phase, like a seed. But I don’t want to talk about megaviruses, fascinating though they are – and very new discoveries. I want to talk about viroids, which are plant pathogens. They consist of short strands of RNA, only a few hundred nucleases long, without the protein coat that characterises viruses, and their existence tends to support the ‘RNA world hypothesis’. It was the discoverer and namer of viroids, Theodor Diener, who pointed out that they were vitally important macromolecules for explaining essential steps in the evolution of life from inanimate matter. That was back in 1989, but his remarks were ignored, and only rediscovered in 2014. So viroids are now a big focus in abiogenesis. They’ve even been called living relics of the pre-cellular RNA world.
Jacinta: Okay, I’m more or less impressed. We’ll have to do more on abiogenesis in the future, it’s an intriguing topic, with more breakthroughs in the offing it seems. ..
the anthropic principle lives on and on
The anthropic principle, the idea that the universe – and let’s not muddle up our heads with multiverses – appears to be tweaked just right, in a variety of ways, for the existence and flourishing of humans, has long been popular with the religious, those invested in the idea of human specialness, a specialness which evokes guided evolution, both in the biological and the cosmological sense. And, of course, God is our guide.
Wikipedia, God bless it, does an excellent job with the principle, introducing it straight off as the obvious fact that anyone able to ascertain the various parameters of the universe must necessarily be living in a universe, or a particular part of it, that enables her to do the ascertaining. In other words the human specialness mob have it arse backwards.
So I’ll happily refer all those questing to understand the anthropic principle, in strong and weak forms, it proponents and critics, etc, to Wikipedia. I’ve been brought to reflect on it again by my reading of Stephen Jay Gould’s essay, ‘mind and supermind’, in his 1985 collection, The Flamingo’s Smile.
Yes, the anthropic principle, which many tend to think is a clever new tool for deists, invented by the very materialists who dismiss the idea of supernatural agency as unscientific, is an old idea – much more than 30 years old, because Gould was critiquing not only Freeman Dyson’s reflections on it in the eighties, but those of Alfred Russel Wallace more than a century ago, in his 1903 book Man’s Place in the Universe. Gould had good reason for comparing Dyson and Wallace; their speculations, almost a century apart, were based on vastly different understandings of the universe. It reminds us that our understanding of the universe, or that of the best cosmologists, continues to develop, and, I strongly suspect, will never be settled.
Theories and debates about our universe, or multiverse, its shape and properties, are more common, and fascinating, than ever, and accompanied by enough mathematics to make my brain bleed. The other day one of my regular emails from Huff Po science declared that maybe the universe didn’t have a beginning after all. This apparently from some scientists trying to grab attention in a pretty noisy field. I’ve only scanned the piece, which I would hardly be qualified to pass judgment on. But not long ago I read The Unknown Universe, a collection of essays from New Scientist magazine, dedicated to all ideas cosmological. I didn’t understand all of it of course, but genuine questions were raised about whether the universe is finite or infinite, about whether we really understand the time dimension, about how the laws that govern the universe came into being, and many other fundamental concepts. It’s interesting then to look back to more than a century ago, before Einstein, quantum mechanics, and space probes, and to reflect on the scientific understanding of the universe at that time.
A version of the universe, based on Lord Kelvin’s calculations, used by Wallace
In Wallace’s time (a rather vague term because the great scientist’s life spanned 90 years, which saw substantial developments in astronomy) the universe, though considered almost unimaginably massive, was calculated to be much smaller than today’s reckoning. According to a diagram in Man’s Place in the Universe, it ended a little outside the Milky Way galaxy, because we had no tools at the time to measure any further, though Lord Kelvin, the dominant figure in physics and astronomy in the late 19th century, made a number of dodgy calculations that were taken seriously at the time. In fact, Kelvin’s figures for the size of the universe, and for the age of the earth, though too small by orders of magnitude, were considered outrageously huge by most of his contemporaries; but they at least began to accustom the educated public to the idea of ginormity in space and time.
But size wasn’t of course the only thing that made the universe of that time so different from our own conceptions. The universe of Wallace’s imagination was stable, timeless, and, to Wallace’s mind, lifeless, apart of course from our planet. However, he doesn’t appear to have any good argument for this, only improbability. And an odd kind of hope, that we are unique. This hope is revealed in a passage of his book where he goes off the scientific rails just a bit, in a paean to our gloriously unique humanity. A plurality of intelligent life-forms in the universe
… would imply that to produce the living soul in the marvellous and glorious body of man – man with his faculties, his aspirations, his powers for good and evil – that this was an easy matter which could be brought about anywhere, in any world. It would imply man is an animal and nothing more, is of no importance in the universe, needed no great preparations for his advent, only, perhaps, a second-rate demon, and a third or fourth-rate earth.
Wallace, though by no means Christian, was given to ‘spiritualism’, souls and the supernatural, all in relation to humans exclusively. That’s to say, he was wedded to ‘human specialness’, somewhat surprisingly for his theory of evolution by wholly natural selection from random variation. This is the chain, it seems, that links him to modern clingers-to the anthropic principle, such as William Lane Craig and his epigones, who must needs believe in a value-laden universe, with their god as the source of value, and we humans, platonically created as the feeble facsimiles of the godhead, struggling to achieve enlightenment in the form of closeness to the Creator, with its appropriate heavenly rewards. And so we have such typical WL Craigisms as ‘God is the best explanation of moral agents who apprehend necessary moral truths’, ‘God is the best explanation of why there are self-aware beings’ and ‘God is the best explanation of the discoverability of the universe [by humans of course]’. These best explanation ‘arguments’ can be added to ad nauseum, of course, for they’re all of a part, and all connected to the Wallace quote above. We’re special, we must be special, we must be central to the creator’s plan, and our amazingness, our so-much-more-than-animalness, in spite of our many flaws, suggests a truly amazing creator, who made all this just for us.
That’s the hope, captured well by the great French biologist Jaques Monod when he wrote
All religions, nearly all philosophies, and even a part of science testify to the unwearying, heroic effort of mankind desperately denying its contingency.
I think modern philosophy has largely moved on from desperate denialism, but Monod’s remarks certainly hold true for religions, past present and future. Basically, the denial of our contingency is the central business of religion. It’s hardly surprising then that the relationship between religion and science is uneasy at best, and antagonistic at its heart. The multiverse could surely be described as religion’s worst nightmare. But that’s another story.
why are our days getting longer?
I’ve just finished reading a book by the Welsh biologist and science communicator Steve Jones entitled Coral; a pessimist in paradise, which covers a helluva lot of ground and makes me feel inadequate as most science writers do, but one of the many things he has taught me about – something I didn’t know that I didn’t know – is that the days are getting longer, in an inexorable process of rotational slowing. This fact, and the reasons behind it, were further confirmed for me today in an episode of an elegant little podcast out of the University of Houston, called The engines of our ingenuity. I just happened to be browsing through the science and scepticism podcasts on my TV, and I sampled a few curiously titled ones…
Let me backtrack a bit. I’m very very poor (from an affluent western perspective of course) but I received a HD TV from my neighbour recently as part of a complicated deal, and now I can watch free-to-air channels I didn’t have access to before, and what’s more I’ve managed to buy a device which I’m sure many people out there know all about, called an Apple TV, which is so cheap that even I can afford it without too much suffering (what’s a few days without food? it’ll probably extend my lifespan). So now I can explore an almost endless variety of podcasts, vodcasts and classic film noir movies on youtube. That reminds me, one of the podcasts I’ve listened to, the Brain Science Podcast, was all about brain fitness – at least the episode I tuned into was – and inter alia the interviewee informed us that just about the worst thing for the brain was sitting around all day watching TV – Apple or no Apple, presumably…
Anyway I listened to this informative and also charmingly poetic three-minute episode of The engines of our ingenuity, entitled ‘How far the moon?’, narrated and presumably written by Dr John Lienhard. So I’ll share the info, if not the poetry, here.
Our earth spins at a pretty well constant rate because of the forces that set it in motion in the first place and because of Newton’s first law of motion which, put simply, states that an object will stay in the same state (resting or in motion) unless an external force acts on it. A ball spinning in the air will slow down because of air friction, but the earth is spinning in a vacuum, essentially – there’s nothing to slow it down.
Well, not quite. The earth is slowing down, and all in accordance with Newtonian physics. And it’s all due to the moon. Each day is about a twelfth of a second longer than it was when the Egyptians built the pyramids. Doesn’t sound that much, but 4000 years is a mere blip in geological and cosmological time. The moon drags at the earth gravitationally, creating high tides and low tides at a regular rate, and slowing our rate of rotation. But our earth has a much greater influence on the moon than vice versa, the moon having only an eightieth of earth’s mass. This gravitational effect slowed down the moon’s spin until it was in synch with the earth, and locked into the earth’s movement like a dancer being swung around by its partner. And so the moon faces us always. The slowing down of the earth due to the moon’s influence had the effect of loosening the embrace – the moon is slowly moving away from us. Just as a spinning dancer or skater extends her arms out to slow down or pulls her limbs in to speed up. The moon moves away from us so that our combined rotational inertia remains constant. The distance between earth and moon, and the speed at which the moon moves away from us, is being measured thanks to an instrument, placed on the moon by Apollo astronauts, which reflects laser beams from earth. Through measuring the time taken for the beam to return, we know that the moon is moving away from us at a little under 4 cms a year. Back in the dim distant past, days lasted only 12 hours, and the moon was half of today’s distance from us. This has affected the shape of the earth, which is gradually becoming more spherical. The earth’s diameter is at its greatest at the equator and at its smallest at the poles, because of centrifugal forces operating against the force of gravity…
Okay, let me get clearer on this, with the help of this source, among others. Isaac Newton accepted the mathematics and the accuracy of Kepler’s laws of planetary motion, but the great unanswered question was why planets – and moons – traced out these orbits. Newton’s own first law stated that an object will continue in its trajectory (that is, in a straight line) or in its resting state, unless some external force acted upon it to speed it up or slow it down. This state is called a state of inertia. Clearly planets and moons were being acted upon by some force, which could only be exerted by the object being orbited. This force might be called a centripetal force, though that doesn’t explain it in this case. If you swing a stone around on the end of a string, you apply a force to the stone to keep it going, but the string, and your hand holding the string, exerts a force on the string to keep it ‘in orbit’. Its motion will be circular, providing you keep your hand still, because the length of the string is constant. But there’s nothing obvious attaching the moon to the earth. Newton pondered this for some time, until one day the apple dropped.
I’m thinking that, if the moon is moving away from us, its orbit can’t be entirely circular, it must be spiralling outwards, ever so slightly. In any case, the moon pulls the earth out of shape, and that is due to a centrifugal force that balances the centripetal force exerted by the earth on the moon. The moon is moving away due to a reduction in both these forces, and a slowing of the earth’s rotation, and hence of the moon’s orbit.
But sadly, it gets more complicated than that! This is the Newtonian explanation of how these forces operate, but it doesn’t really answer the why question. I’m not going to go deeply into that here – as if I could – but I’ll end with a quote from an astronomer’s explanation, not so much about the earth’s slowing, but about the moon’s behaviour, in terms of Newtonian and then Einsteinian physics:
First case: – Why does the Moon orbit the Earth? It just does. And you can understand how it does by analyzing the forces on the Moon caused by its orbit and finding the forces pushing in and out are equal.
Second case: – Why does the Moon orbit the Earth? Because the Earth distorts spacetime in the vicinity of the Moon, and causes it to orbit the Earth the way it does and the balance of forces to come out the way it does.
So why do massive objects distort space-time? Apparently they just do?
how to debate William Lane Craig, or not – part 5, the fine-tuning argument
gee thanks, goddie – and can you help me win my soccer game on saturday?
Dr Craig’s fifth argument is the well-known fine-tuning argument. Once again I should point out that when Dr Craig brings up these science-related topics it isn’t from a fascination with science itself – indeed Dr Craig likes to use the term ‘scientism’ when he refers to science other than when he’s using it to support his obsession. He uses science solely to mine and manipulate it to convince himself and others that there’s a warrant for a supernatural agent who has a personal love for him. So you should always consider his use of science with that in mind. And you should ask yourself, too, why is it that the physicists and cosmologists and mathematicians of the world, the people who work on a daily basis with the so-called laws of nature and the physical constraints of the universe, are by and large so completely lacking in belief in a personal deity? This is a sub-population that is more atheistic than any other sub-group on the planet. How does Dr Craig account for this? Madness, badness, indoctrination? How is it that the greatest physicist, by general acclaim, of the twentieth century, Einstein, regularly described belief in a personal god as a form of childishness? Why is it that Bertrand Russell, one of the greatest mathematicians and logicians of all time, wrote, ‘I am as firmly convinced that religions do harm as I am that they are untrue’? What is it with the Richard Feynmans, the Stephen Weinbergs, the Stephen Hawkings of this world that they’ve been so indifferent or hostile to the claims of religion? Perhaps Dr Craig should consider launching a wholesale attack on these disciplines, since they seem such a breeding ground for views so completely out of synch with his obsessions. How can they not know that all their researches and discoveries converge on the screamingly obvious fact that a loving human-focused supernatural being designed everything. What a bunch of blind fools.
The fine-tuning argument has been around for a long time despite its seeming ultra-modernity, though of course it gets updated in terms of constants and constraints. It’s of course, a rubbish argument like all the others. This universe wasn’t fine-tuned for anything. There was no tuner, as far as we know, and it would be impossible to predict what possibilities could emerge from the hugely complex and almost entirely unknown preconditions of the universe’s existence. Our universe will provide us with many many surprises long into the future, and I would not be surprised if those surprises include forms of life hitherto thought impossible, due to the ‘laws of nature’. Dr Craig claims that the various constraints and quantities that he talks about are independent of the laws of nature, which is a nonsense, as it’s only through our application of physical laws that we’ve been able to determine these quantities. So I don’t know what to make of his claim that these constraints aren’t physically necessary. The constraints exist as an essential part of the physical nature of this universe. The question of necessity or chance just doesn’t arise. These are the constraints we have to work with, and we find that, within these constraints, intelligent life is clearly possible, though perhaps very rare, though perhaps not so very rare as we once thought. I think we must all agree that we live in exciting times in the search for extra-terrestrial intelligence and extra-terrestrial life more generally. We’re homing in on the zones elsewhere that meet all the conditions for the emergence of life, and I believe we will find that life in time. Intelligent life, by our standards, will no doubt take longer.
Dr Craig says the odds of this universe being life-permitting are astronomically small. Some cosmologists agree, but they don’t then make any leaps to a supernatural cosmic designer. And I mean none of them do. It’s interesting that the cosmologist Alan Guth, to whom Dr Craig has already referred, believes that humans will one day be able to design new universes, no doubt with the help of quantum computers, and there are others who suggest that this may be how our universe came into being. All highly speculative stuff, and not particularly mainstream, but good fun, and worthy of reflection. Others, such as Stephen Hawking, have proposed a superposition of possible initial conditions for the universe which provides for an ‘inevitability’ of us finding ourselves in just this kind of life-sustaining universe at a later stage. It’s all to do with the manipulation of time-perception apparently. This hypothesis eliminates the need to posit a multiverse. There are many other hypotheses too, of course, including the multiverse, the bubble universe and others. It’s an exciting time for cosmology. Tough, but exciting, and far more interesting and rewarding than theology, I can promise you that. As students, I hope you continue to follow this stuff, for its own sake, not to mine it as confirmation for preconceived ideas.
fountains of good stuff 1: introduction
Here is my first podcast in the new series, which I hope to continue with into the future, having worked out a simple format.
fountains of good stuff 1: introduction
Hi, my name is Stewart Henderson, and this is my introduction to fountains of good stuff, a series which will explore all sorts of things we’re learning about the brain, the galaxy, the past, the laws of nature, the strange behaviour of humans, and anything else that happens to take my fancy and which I think may be of interest to, well, somebody out there. In my fantasy world, I’d love to be constantly immersed in all this good stuff, learning about it, reading about it, talking to clever people about it, picking people’s brains about it, arguing about it, and just generally wallowing about in the stuff. Okay, with a dollop of sex thrown in occasionally. It’s a kind of lifelong learning thing, because you know, you’re never too old to learn, and learning is the best way to keep you young and enthusiastic, and to maintain the plasticity of your brain, apparently.
Now it just so happens that I myself am very very old, so I think it’s most appropriate that I should be presenting this ‘fountain of youth’-type series which I’m hoping will flow on and on and on unto oblivion, you know, sans teeth, sans eyes, sans taste, sans everything. And I’m hoping you can follow me along the downward spiral. Should be fun, n’est-ce pas?
So what’s the purpose of all this? Well, in my dotage, I’ve become very interested in knowledge, in finding things out, and also thinking about how we know things. Not in a philosophical way, but in a naïve, childlike way – a sense of wonder, often confusion, sometimes excitement, and sometimes skepticism. And maybe, this is philosophy, I don’t know. It seems to me that, as I get older, I become almost panic-stricken about how little I know about anything, as if I’ve wasted my life, or as if haven’t sufficiently explored and exercised this amazing thing I have inside my head.
There’s a funny story told about Pliny the Elder, a great Roman intellectual who had a servant follow him around all day, reading to him from works of natural history, the science of the time, so that when he was in his bath, sitting on the dunny, or at the dinner table, none of his time would be wasted, he’d be absorbing information during every waking hour. How he’d have loved the modern world of podcasting.
Of course, this is based on the notion of the brain as a great big bucket which you can pour contents into until it’s full up and you know everything, but the brain doesn’t work like that, and Pliny would’ve been well aware of that, he would’ve known that memory is unreliable, that we forget more than we retain and so on, but I can certainly sympathise with his hunger for more knowledge, perhaps in the hope that it would all somehow combine together in his mind, and even that his mind would transform it into more than the sum of its parts, like an oven does to the ingredients of a soufflé. Incidently Pliny, Jupiter bless him, was exactly my age when he died, overcome, so it’s said, by the fumes of Vesuvius, on the same day that it buried Pompei under its lava and ash.
Now where was I? Knowledge. I’m no scientist, in fact through most of my life I’ve been an arty-farty bludger type, but I’ve always been impressed, in fact in awe, of the achievements of science, and I’ve certainly always been interested in the questions science seeks to answer. What does it mean to be alive? Why do we sleep for so much of our lives? How did the world we live in come to be? What do we mean by ‘the world’? Is that an obsolete term or does it still have its uses? How is it that my pet cat has the same shape face as a lion, or a tiger? Exactly how is it different, and how the same? Why does my shit smell so bad, though not as bad as that of other people? Why am I so struck by the beauty of women, while noting that beauty’s infinite variety? How long will our species last? Is there life elsewhere in our solar system?
The number of questions is infinite, of course, or potentially so, and some of these questions we already have answers for, though there may turn out to be better answers, and there are some questions we’re close to finding answers for, and some questions that are unanswerable, or badly framed, or not worth worrying about, or too much of a worry. There are questions we can answer in a jiff via Wikipedia, and questions we wonder if anyone has ever asked before.
Whatever the questions, they all have something to do with knowledge, and it seems to me that science can always be let in to lend a hand. I don’t think science is anything mysterious or scary, it’s simply the way to knowledge. At least, the knowledge I’m interested in. Science is whatever generates reliable knowledge about the world. I’ve heard people say that ‘science doesn’t know everything’, as if science was a person, probably male, obsessive and slightly mad. They say this as if they think this science bloke is getting too big for his boots and needs to have a wadge of humble pie stuffed down his throat. But if you just treat science as an attempt to arrive at reliable knowledge, you’ll see how absurd this statement is. People try to arrive at reliable knowledge because they don’t know everything. And I would say that the vast majority of scientists are happy to admit that they don’t know much about anything. That’s what makes it such a challenge and so much fun, that there’s so much to learn and so much to think about. And if you can think of any other approach to knowledge that is of any use at all, please let me know, I’d be fascinated.
I know some philosophers say there’s no such thing as the scientific method, and I agree. There’s nothing you can point to, or write down, or put into a formula, and say, there’s the scientific method. I think of science as using an open-ended set of methodologies, each one more beautiful than the other, for arriving at reliable knowledge. They generally involve a lot of prior knowledge, a fair degree of creativity, and a balance of open-mindedness and skepticism. Now, I think I understand the Darwin-Wallace theory of natural selection. I can’t say that I fully understand Einstein’s Theory of Relativity, but I know enough about it to be pretty sure that the methods Einstein used to arrive at his theory have pretty well nothing in common with the methods of Darwin and Wallace. In fact I’d say that even Darwin and Wallace arrived at much the same theory using different methods, according to their different natures and experience. That’s the beauty and creativity of science, and there’s plenty of that around.
Science is essentially a way of life, and it’s the best diversion from the perils of self-absorption ever devised.
So I want to celebrate science and its achievements from my lay perspective, very much in the spirit of Bill Bryson in his wonderful book ‘A short history of nearly everything,’ and I immediately identify with Bryson when, in the beginning of his book, he recalls a text-book diagram from his school-days, which cut through the Earth’s inner layers, and the text told him that the inner core was made of molten nickel and iron, at a temperature something like the surface of the sun, and he asked himself – how did they know that? And still asks himself, as I do. How do they know that light travels at about 300,000 kms per second? How do they know that Proxima Centauri, the nearest star to us apart from the sun, is 4.24 light years away? How do they know? Well, it’s not really a mystery, and I’m hoping, as maybe old Pliny did, that it’ll all come together in my mind one day. With a bit of work.
I won’t always be talking about scientific knowledge, though, and how we come to know things. I have an interest in history, in biography, and in religion, its psychology, its history, and its claims to knowledge and influence. I’ll be talking about important and fascinating figures in intellectual history, from Hypatia to Antoni van Leeuwenhoek to Harry Hess. I’m doing it for self-education and for communication, so if you hear any of these talks, and think you’ve learned something from them or been stimulated by them to learn more, I hope you’ll recommend them to your friend. And some people, I hear, have more than one.
So that’s my introduction to these fountains of good stuff. I hope it wasn’t too discombobulating, and I’m hoping that one day, if I get rich, or meet someone who’s a techno wizard with a bit of time on their hands, that I’ll be able to add a few bells and maybe even a whistle or two, to make it all sound really cool.
Meanwhile, I hope you tune into my first fully gushing podcast, which will be about dolphins and their brains. See you then.
is there life on enceladus?
a cool place – and note the tiger stripe
The Curiosity landing has been fabulously successful, and it’ll certainly be worth keeping tabs on the rover’s findings. I posted recently on the possibility of life on Mars, not a couple of billion years ago, as many Mars experts think probable, but right now. The Curiosity rover, as we know, will be investigating this possibility further, but meanwhile there are other possibilities of finding extra-terrestrial life in this solar system, and one of the best places to look, I’m reliably informed, is Enceladus, a tiny moon of Saturn.
Enceladus is only about 500 kilometres in diameter, but its surface has intrigued astronomers ever since Voyager 2revealed detailed features in the early eighties, indicating a wide range of terrains of varying ages. Data from the Cassini spacecraft that performed fly-bys in 2005 showed a geologically active surface, with the most spectacular feature being a large volume of material, mostly water vapour, issuing from the southern polar region. This indicated the existence of ice volcanoes, or cryovolcanoes, which have also been observed elsewhere, and were in fact first observed by Voyager 2 on Triton, Neptune’s largest moon. However, on Enceladus what we have are more like geysers spewing out material from an area known by observers as ‘the tiger stripes’, a series of prominent, geologically active ridges. This material is now known to account for much of the outermost E ring of Saturn, within which Enceladus has its orbit, though a certain amount falls back onto the moon as snow.
Finding water on any object in the solar system obviously excites the souls of astrobiologists. A report from a May 2011 conference on Enceladus stated that this moon “is emerging as the most habitable spot beyond Earth in the Solar System for life as we know it”. However, there are plenty of sceptics, or I should say cautious questioners. First, the existence of water vapour spumes doesn’t necessarily entail liquid water below the surface – for, in spite of the thrill of detecting snow in large quantities on the surface, liquid water is generally regarded as essential to finding life. And even if we assume liquid water…
Some analysts argue that the spumes may be a result of sublimation – a change from a solid, icy state to a vapour, missing out on the liquid phase – or of the decomposition of clathrate deposits. A clathrate is a type of ice lattice that traps gas [methane clathrates are found at the polar regions of Earth]. However, the recent discovery of salt in these plumes has made these possibilities less plausible. Salt is more likely to be associated with liquid water, but hydrogen cyanide, also recently found, would have been expected to react with liquid water to form other compounds, not found as yet. In short, the jury is still out on the presence of liquid water.
And assuming there is liquid water, how could we test for life within it? With great difficulty, obviously. Analysts would be searching for biomarkers, ‘chemicals that appear to have biological rather than geophysical origins’ [Cosmos 44, p78]. Photosynthetic production wouldn’t be an option, so other systems are being hypothesised, including a methanogenic system in which methane is synthesised from carbon dioxide, or a system of metabolizing acetylene, which occurs on Earth. Traces of acetylene have been found on Enceladus. Other biomarkers include amino acids with the right chirality – that’s to say a strong chiral preference, one way [as found on Earth] or its opposite. Amino acids with no chiral preference are likely to be abiotic.
To test for such biomarkers would require new instrumentation and another visit to this intriguing moon. Something else to look forward to. What would we do without anticipation?