Sunday, December 27, 2009
Saturday, November 7, 2009
The origins of life, nucleic acids, purines, pyrimidines and extra-terrestrial cyanide
Newsflash: Monday 10th October, 2016
Have just come across this item in the Mail.
http://www.dailymail.co.uk/sciencetech/article-3830773/The-secret-ingredient-life-Earth-THICKENER-kick-started-evolution-living-creatures.html
I strongly recommend it, especially as there are faint echoes of the thinking in this posting of mine from way back in 2009.
Start of original posting:
An opportunity has just presented itself to share with my fellow earthlings an idea that's been fermenting in this senescent brain for some time. It concerns the building blocks of DNA and RNA - the purine and pyrimidine bases. These are the flat stackeable molecules that make up the base pairs in double-stranded DNA - Watson and Crick's double helix- and thence the triplet genetic code.
Left: pyrimidines and purines. Right: a pyrimidine nucleotide showing the intermediate ribose sugar between a pyrimidine base and phosphate
Why were these particular molecules selected from the primeval soup? Could other molecules have served in their place? Did adenine and guanine (the purines) and cytosine, thymine and uracil (the pyrimidines) just happen to be "lying around", so to speak, in some primeval rock pool, or forming in the vicinity of a hydrothermal vent?
I tried tackling it first from a physicochemical standpoint. What conditions would be needed for any kind of spontaneous chemistry to occur in a puddle say on Earth? The classic Miller-Urey experiments you may recall subjected the assumed constituents of Earth's proto-atmosphere to electric discharges, in an attempt to generate the precursors of proteins and nucleic acids (amino acids, purines and pyrimidines). Glycine - the simplest of the amino acids- was formed, but that was hardly a chemical cornucopia.
The Miller-Urey apparatus. The test mixture of water, methane, ammonia, hydrogen and carbon monoxide was intended to replicate the then-imagined reducing atmosphere. Current thinking is that the main carbon component was CO2 rather than methane CH4. Interestingly, substituting CO2 for methane gives the same range of amino acid and other products, provided that oxygen is excluded.
See wiki for more details
See wiki for more details
One of the chief problems would have been intense uv radiation from space - without oxygen, there would have been no ozone "sun-screen". So maybe the first requirement was to generate sun-screen agents in situ. Purines and pyrimidines all absorb strongly in the ultraviolet:
From left: adenine ( as the nucleotide AMP ); uracil (as UMP); cytosine (as CMP); guanine (as GMP)
So if they formed by accident a kind of proto-Darwinian natural selection would operate. Further molecules could then evolve, protected by the sun-screen molecules. What about the sugars - the five carbon ribose and deoxyribose? Could they have developed initially in a permissive role, simply to allow more chemistry to proceed?
If life did evolve on land, say in a rock pool receiving intermittent rain, and exposed to all weathers, then there needed to be a mechanism to protect against freezing or evaporation. Chemistry generally needs to be in solution if one is to synthesise. Well, there's a possible role for sugars. Firstly, they depress freezing point, ie have anti-freeze properties. What's more, a sugar solution tends to go syrupy when water is evaporated. It's often quite difficult to drive off the last of the water. Sugar molecules bristle with hydrogen-bonding OH groups which cling tenaciously to water.
Sun-screen agent, anti-freeze - are these the properties of purines, pyrimidines and sugars that caused them to become the building blocks of life?
What about those five chemical bases? Where did the carbon and nitrogen come from for their cyclic structures?
It was the article in the current New Scientist ("Was life founded on cyanide from space crashes?") that provided another piece of the jigsaw. It's proposed that life on earth was seeded by cyanide , -CN, in asteroids. As written it's a free radical, not a stable molecule. It would have to be HCN, or a metal cyanide, eg KCN. Now if you look at the detailed structure of purines and pyrimidines, you will see that all of them feature an alternation of -C-N- in their rings. There are some -C-C bonds as well, but the cyanide dimer cyanogen N-C-C-N could have provided that.
As soon as I started googling I struck pay dirt, with a 1978 paper describing how solutions of HCN began to form purines and pyrimidines spontaneously in the presence of alkali.
Read the New Scientist article and comments, five at the time of writing, with the suggestion that cyanide is the carbon precursor par excellence, not only for its association with nitrogen, but for being "electron-rich" (my term), given the presence of that triple bond between the two atoms, representing three shared pairs of electrons.
Standard valence formula (lower left); electronic configuration (upper right). Of the six electrons in the triple bond, 4 are available for forming new chemical bonds with additional atoms of carbon, nitrogen, hydrogen etc.
Further reading: for a critique of the Miller-Urey experiment, indeed, the entire idea that life could have evolved spontaneously, see the article by John Peet.
Postscript: it's all been thought of before: at least the cyanide to purines route.
And, to end on a light note:
Postscript: added October 8, 2016:
It's nigh on 7 years since penning this post, which still continues to receive a trickle of visitors, according to my sitemeter. Much water has flowed undr this blogger's bridge these last few years. First there's this retired science bod's explanation for the Turin Shroud - a flour/oil imprint from a live adult male (probably 13th century!) onto linen intitially, then roasted, then washed, to produce the final faint, enigmatic 'negative' image. See my specialist TS site for details.
There's also my theory for Stonehenge, and indeed most standing stones, circles and henges in the UK, namely that they were sites for "sky burial", or as I prefer to call it, AFS (avian-facilitated skeletonization). See the most recent postings on this site for the basis of this interpreation, much resting on the crude and rustic layout of what has been dubbed "Seahenge" uncovered by storms on the Norfolk coast in the late 1990s.
Labels:
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origin of life,
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Friday, October 30, 2009
Talking Energy - an individual perspective
Today's the day when the Telegraph launches its "Talking Energy" feature in association with E.on, the energy supplier.
One is invited to join the debate . Four of us bloggers are each given individual "home pages" on the website: Christina O, SabinaA, the recently-arrived Robert and myself.)
Whether, in the case of E.on, one calls it a public consultation exercise or a PR campaign, does not worry this blogger unduly. Given the way that the AGW debate has been politicized and polarized, any new forum is to be welcomed if it allows the voice of reason and real science to be heard without all the personal aggro.
So this blogger has signed up, asking that any new forum be proactively moderated. I suggested in an email that it could usefully take a leaf from New Scientist about how to moderate. (For example, the NS has no time or patience for those persistent conspiracy theorists who clutter up its comments, and a good thing too.)
"Reactive moderation", as one sees on My.Telegraph, may be cost-effective, but it degenerates quickly into unseemly dogfights, ending with entire posts and comments - good as well as bad - being deleted by the tardy moderators.
I received an electronic galley proof of the Telegraph/Eon opening gambit, scheduled for later today tomorrow, and submitted my 600 words yesterday, along with mugshot and bio' as requested. One waits with bated breath (more commonly rendered these days as "baited breath", with visions of mouse traps and Cheddar cheese*).
I'm not giving any secrets away by telling you that the central message of the exercise is that energy companies like E.on are confronted with what they call a "trilemma". (A parallel campaign on YouTube whence came my graphics is already underway with that questionable t-word neologism in prominence). The trilemma refers to so-called "conflicting" demands that future energy supplies be: 1. Green (low-carbon) 2. Affordable and 3. Reliable.
Well, one could be pedantic and say there's nothing conflicting there - they are merely three desirable criteria that need to be met simultaneously. Otherwise our lives would be burdened with trilemma, like where to live (it's got to be a nice area, affordable, handy for public transport).
Rather than nitpick, this blogger decided to focus on renewable energy, and how it might be made more reliable, given fluctuations in wind speed affecting turbine output etc. Clue: Dinorwig.
I'll let the Telegraph publish first, then wait a day or two.
Watch this space!
* Cruel Clever Cat by Geoffrey Taylor:
This little ditty first appeared in an anthology called Catscript, edited by Marie Angel. However, it was first published in 1933 in a limited edition of Geoffrey Taylor’s poems entitled A Dash of Garlic.
Additional reading E.on powers down to cut carbon and costs
Interesting to see the spotlight being put on our PCs - and rightly so, when you consider the heat that comes - not just from the laptop itself, but the charger too.
Energy-saving tip: when using one's laptop, switch off a light or other appliance that would normally be on, if it's superfluous to requirements when you are online.
Update: Thur 5th November: Here's a C&P of my first post on the E.on site. Having been up for a few days now, it would not seem a terrible breach of protocol to add it here for archival purposes:
Who can doubt that the future lies with renewable energy, and that we Brits are blessed with the stuff – existing or yet-to-be-realized.
First, there are those wind turbines – not the stuff of Wordsworthian rapture I grant you - but they are increasingly being sited offshore.
Then there’s solar energy, with a choice of two panels for your roof – the older thermal, or the state-of-the-art PV panels that can feed the electricity you don’t use into the National Grid.
And there’s wave power – which is a kind of secondhand solar power, recalling that weather and wind are due to unequal heating of the Earth’s surface.
And there’s even the dear old man in the moon, not wishing to be outshone by his flashy big brother, who contributes the prospect of tidal power. Just wait until we have a hydroelectric barrage across the Severn Estuary, supplying maybe as much as 10 per cent (?) of our power supply. (Yes, there are downsides, needless to say, to any big scheme, in terms of amenity, effect on wildlife, capital cost, the carbon-footprint of setting up etc. But let’s stick with the broad brush today.)
The problem with most of the renewable schemes is that the end-product – electricity, that energy-carrier par excellence – is generated at scattered locations across the country, supply may be intermittent, or supply may not match demand around the clock or calendar.
Is there a solution? Yes, there probably is, though it’s not always a panacea. One is talking about big money upfront, and, more to the point, big commitment.
But unless or until fusion power becomes a reality – which may take decades, centuries even – then there is no Plan B, assuming one is not a unbudgeable climate change denialist who thinks the world's scientists in their droves have abandoned all reason in condemning those fossil fuels.
So what is the solution? Simply go to the wiki page on Pumped Hydroelectric Storage, and it’s all there.
Britain already has 4 PHS stations – two in Scotland, two in Wales, and now needs a lot more in different shapes and sizes.
The principle is simple. One has two bodies of water – a lower and upper level. When there’s a surplus of electrical power, say from wind farms during the night, water is pumped from the lower to the upper level. When there’s extra demand, and the conventional stations are struggling to cope, water runs back through turbines, generating electricity.
It’s the closest one can get to “storing” electricity as the potential energy of a head of water. What’s more, the efficiency is surprisingly high – 80 per cent or more they claim in a well-designed system.
Do read the article, to see the new and imaginative ways of developing the principle. The Japanese have used the sea on Okinawa as one of the two levels, the other being a reservoir at the top of the headland.
The Danes have a plan that does not even need two levels – the water is simply pumped into a giant bladder which gradually plumps up, creating its own head. Sand is laid on top to get extra oomph.
My favourite is the salt-mine idea. We have lots of worked-out salt-mines in Cheshire and elsewhere. You pump water down into the old-workings, and site your upper reservoir on the surface. Yes, the water becomes brine, so all the equipment has to be corrosion-resistant. But there’s an upside too: once the water becomes saturated brine, it’s 20 per cent heavier than pure water, so becomes a more efficient energy-transfer medium.
What is it they say – where there’s a will, there’s a way!
One is invited to join the debate . Four of us bloggers are each given individual "home pages" on the website: Christina O, SabinaA, the recently-arrived Robert and myself.)
Whether, in the case of E.on, one calls it a public consultation exercise or a PR campaign, does not worry this blogger unduly. Given the way that the AGW debate has been politicized and polarized, any new forum is to be welcomed if it allows the voice of reason and real science to be heard without all the personal aggro.

I received an electronic galley proof of the Telegraph/Eon opening gambit, scheduled for
I'm not giving any secrets away by telling you that the central message of the exercise is that energy companies like E.on are confronted with what they call a "trilemma". (A parallel campaign on YouTube whence came my graphics is already underway with that questionable t-word neologism in prominence). The trilemma refers to so-called "conflicting" demands that future energy supplies be: 1. Green (low-carbon) 2. Affordable and 3. Reliable.
Well, one could be pedantic and say there's nothing conflicting there - they are merely three desirable criteria that need to be met simultaneously. Otherwise our lives would be burdened with trilemma, like where to live (it's got to be a nice area, affordable, handy for public transport).
Rather than nitpick, this blogger decided to focus on renewable energy, and how it might be made more reliable, given fluctuations in wind speed affecting turbine output etc. Clue: Dinorwig.
I'll let the Telegraph publish first, then wait a day or two.
Watch this space!
* Cruel Clever Cat by Geoffrey Taylor:
Sally, having swallowed cheese,
Directs down holes the scented breeze,
Enticing thus with baited breath
Nice mice to an untimely death.
Directs down holes the scented breeze,
Enticing thus with baited breath
Nice mice to an untimely death.
Additional reading E.on powers down to cut carbon and costs
Interesting to see the spotlight being put on our PCs - and rightly so, when you consider the heat that comes - not just from the laptop itself, but the charger too.
Energy-saving tip: when using one's laptop, switch off a light or other appliance that would normally be on, if it's superfluous to requirements when you are online.
Update: Thur 5th November: Here's a C&P of my first post on the E.on site. Having been up for a few days now, it would not seem a terrible breach of protocol to add it here for archival purposes:
Who can doubt that the future lies with renewable energy, and that we Brits are blessed with the stuff – existing or yet-to-be-realized.
First, there are those wind turbines – not the stuff of Wordsworthian rapture I grant you - but they are increasingly being sited offshore.
And there’s wave power – which is a kind of secondhand solar power, recalling that weather and wind are due to unequal heating of the Earth’s surface.
And there’s even the dear old man in the moon, not wishing to be outshone by his flashy big brother, who contributes the prospect of tidal power. Just wait until we have a hydroelectric barrage across the Severn Estuary, supplying maybe as much as 10 per cent (?) of our power supply. (Yes, there are downsides, needless to say, to any big scheme, in terms of amenity, effect on wildlife, capital cost, the carbon-footprint of setting up etc. But let’s stick with the broad brush today.)
The problem with most of the renewable schemes is that the end-product – electricity, that energy-carrier par excellence – is generated at scattered locations across the country, supply may be intermittent, or supply may not match demand around the clock or calendar.
Is there a solution? Yes, there probably is, though it’s not always a panacea. One is talking about big money upfront, and, more to the point, big commitment.
But unless or until fusion power becomes a reality – which may take decades, centuries even – then there is no Plan B, assuming one is not a unbudgeable climate change denialist who thinks the world's scientists in their droves have abandoned all reason in condemning those fossil fuels.
So what is the solution? Simply go to the wiki page on Pumped Hydroelectric Storage, and it’s all there.
Britain already has 4 PHS stations – two in Scotland, two in Wales, and now needs a lot more in different shapes and sizes.
The principle is simple. One has two bodies of water – a lower and upper level. When there’s a surplus of electrical power, say from wind farms during the night, water is pumped from the lower to the upper level. When there’s extra demand, and the conventional stations are struggling to cope, water runs back through turbines, generating electricity.
It’s the closest one can get to “storing” electricity as the potential energy of a head of water. What’s more, the efficiency is surprisingly high – 80 per cent or more they claim in a well-designed system.
Do read the article, to see the new and imaginative ways of developing the principle. The Japanese have used the sea on Okinawa as one of the two levels, the other being a reservoir at the top of the headland.
The Danes have a plan that does not even need two levels – the water is simply pumped into a giant bladder which gradually plumps up, creating its own head. Sand is laid on top to get extra oomph.
My favourite is the salt-mine idea. We have lots of worked-out salt-mines in Cheshire and elsewhere. You pump water down into the old-workings, and site your upper reservoir on the surface. Yes, the water becomes brine, so all the equipment has to be corrosion-resistant. But there’s an upside too: once the water becomes saturated brine, it’s 20 per cent heavier than pure water, so becomes a more efficient energy-transfer medium.
What is it they say – where there’s a will, there’s a way!
Labels:
AGW,
baited breath,
E.on,
eon,
renewable energy,
talking energy,
telegraph,
trilemma
Tuesday, October 20, 2009
Can entropy decrease in a Big Crunch - without defying the Second Law of Thermodynamics?
The Universe, we're told, is expanding, and has been from the beginning of time - reckoned to be some 13.6 billion years ago. Extrapolate back, and the Universe must have started as something incredibly small, hot and dense - a singularity. Something caused that singularity to explode, in a Big Bang. So far, I'm telling you nothing you have not already heard or read many times.
Will the Universe go on expanding for ever? If you believe in Dark Matter and Dark Energy, then the answer is probably yes. But so far, neither of those hypothetical entities has yet been detected.
So there's another scenario that cannot be dismissed - that expansion will slow, and the Universe will cease expanding and then start collapsing back on itself, ending in a Big Crunch.
Some, myself included, are attracted to this idea, especially as it makes possible the idea of a new Big Bang, indeed, a never-ending series of Bangs and Crunches.
But some objections, or at any rate difficulties, have been raised with the idea of a Big Crunch. One of them is to do with entropy (eg link to Yahoo forum) , and the Second Law of Thermodynamics, which is the one I intend to discuss briefly here today and tomorrow.
The essential idea conveyed by the Second Law is that while energy is never created or destroyed, energy is gradually dispersed, becoming less and less useful. Engines use concentrated energy - fuel - to operate. The end product is waste heat - too dispersed for it to be recaptured and re-used. Indeed, the very act of trying to do that would be self-defeating, incurring a greater energy cost than that recouped. Entropy - the spontaneous tendency for systems to become chaotic, more dispersed, has been successfully analysed statistically in terms of order/disorder, more specifically to do with numbers of possible arrangements. The example I used to give students was this. Imagine you have a neat and tidy bedroom, and there's a strong gust of wind through an open window. Papers get scattered, things fall off shelves etc. Suppose one started with a disordered bedroom, and there was a gust of wind. You would be very surprised if you ended with a tidy bedroom. The probability of a chance event - in this case the wind - producing disorder is hugely greater than that of producing order. Why? Because there are relatively few ordered arrangements compared to the number of disordered ones.
What's all this got to do with cosmology you may ask? Well, we see entropy increase around us on a daily basis - eg salt dissolves in water. The ordered structure of a crystal is replaced with the chaos of dispersed ions in solution. If entropy is steadily increasing, in accordance with the Second Law, then the entropy of the initial singularity must presumably have been minimal, possibly zero - a maximally-ordered system it would seem.
There's a problem, then, with the idea of contraction back to a singularity - the Big Crunch. Why ? Because if the end result is the same singularity, then entropy would decrease steadily during the contraction. But that would be contrary to the Second Law, would it not? Other objections have been raised. If we lived in a contracting universe, salt would presumably still dissolve in water, so we would still be seeing the Second Law in action.
Some have tried to get round the conundrum by introducing the variable of time. It then gets very counter-intuitive, especially the concept of negative time, even history running in reverse! Let's not go there.
I believe there is a way of reconciling the concept of a Big Crunch with entropy and the Second Law.
I shall be posting it here tomorrow!
Wed 21 Oct: Well, tomorrow has arrived, so here's the rest of the story.
It's all to do with the size of the Universe, and its fitness or otherwise to act as an entropy-increasing heat sink. While the Universe is expanding, there is abundant space in which heat can dissipate, or other forms of disorder can occur - eg dilution of gaseous end products etc. In the initial stages of contraction, things would continue much the same while there are still light-years between galaxies, or light-minutes between planets and their nearest neighbours, or even light-seconds between a planet and its moon with intervening space.
But imagine the process of contraction occurring continuously. There will finally come a time when one's perception of nature will change. Galaxies will collide for a start, but let's focus on events at a more local level. Previously there was almost limitless space for heat to dissipate. That will no longer be the case - for two reasons. First there is less space for any new heat to dissipate. Secondly, and more importantly, all the previous heat dissipated into the Universe - which is still out there- will become progressively concentrated. (Reminder; it's not just the contents of space that disappear into a black hole vortex - but the fabric of space-time itself- represented by the mesh in the graphic).
Temperatures in deep space, presently a few degree above absolute zero, will start to increase. The so-called microwave background radiation, a left-over from the Big Bang - will gradually shift and start to shorten in wavelength - first to normal radio frequencies, and then into the infra-red region. That's when things start to get interesting. Engines will no longer run so efficiently, because as background temperatures rise, they will find it progressively harder to dissipate exhaust heat.
Let's now look at the salt/water system. Yes, salt will continue to dissolve in water, suggesting that all is well - that the Second Law is still operating. But as background temperatures increase, the water gets hotter, and if there were still observers around, a point would be reached when the water was no longer liquid at normal temperatures and pressures. In other words, salt could not dissolve in water - if there were no liquid water still in existence!
So there would in fact be a gradual violation of the Second Law as we know it, were the Universe to implode towards a Big Crunch, due to increasing difficulty in dissipating waste heat against a background of rising temperature. In the final stages, the temperatures would become so great that no heat could be dissipated at all. In that situation, one has returned to a state of minimum entropy, but hugely elevated temperatures.
Had a classical thermodynamicist such as Carnot (of eponymous cycle fame) been born into a contracting Universe he would have enunciated the Second Law of Thermodynamics differently, methinks. Quite how it would have been worded I would not care to speculate, except to say it would need to have been heavily qualified re differences between open and closed systems. Could a contracting Universe even be described as "open". Only when the system under study was small, with a sizeable temperature difference between it and everything else "out there"?
What then? See my earlier ideas in the margin (scroll down) which have now been appeared in the MSM - so far with no serious objections being raised. I do not believe that the Big Crunch continues indefinitely. There comes a point when, through frictional forces, the plasma reaches the maximum possible temperature - when its constituent particles (strings?) then moving/vibrating so rapidly that they reach the speed of light, and then transform into massless photons. When that occurs, the system ceases to be a superblack hole, and spectacularly flies apart, creating a new Big Bang...
Update 16th Dec 2014 (5 years later!)
It's temperature that is the key to the conundrum, and the kind of world it creates for those seeking evidence of order/disorder.
In our relatively low temperature world (relying on radiated heat from a single sun that is 92 million miles away) we see lots of evidence of order, notably as the presence of substances as liquids and solids, when at higher temperatures (say in the laboratory) they becomes gases, and at thousands or millions of degrees would be in the plasma state.
But the latter are the temperatures that attain when a Universe contracts down to a black hole, and then singularity, hypothetically or otherwise. So it's useless to go looking for the kind of ordered, low entropy signatures that we are accustomed to. We have to ask ourselves what the signatures are when temperatures are hugely elevated, such that subatomic particles are travelling at speeds close to those of light, and colliding with each other. Those collisions break down the order of associations, but progressively a simplified plasma emerges in which there are the ultimate particles only, whatever they happen to be, all crushed together. The original translational energy across sizeable distances now becomes progressively constrained to vibrations about fixed positions (as in a classical earthly solid), obviously with enormous oscillation frequencies. Thus a kind of high-temperature/highly ordered/low entropy state does (paradoxically perhaps) become finally achievable, but through initial fragmentation, rather than clumping association. In other words, there's more than one route to a low entropy state, depending on temperature.
Will the Universe go on expanding for ever? If you believe in Dark Matter and Dark Energy, then the answer is probably yes. But so far, neither of those hypothetical entities has yet been detected.
So there's another scenario that cannot be dismissed - that expansion will slow, and the Universe will cease expanding and then start collapsing back on itself, ending in a Big Crunch.
Some, myself included, are attracted to this idea, especially as it makes possible the idea of a new Big Bang, indeed, a never-ending series of Bangs and Crunches.
But some objections, or at any rate difficulties, have been raised with the idea of a Big Crunch. One of them is to do with entropy (eg link to Yahoo forum) , and the Second Law of Thermodynamics, which is the one I intend to discuss briefly here today and tomorrow.
The essential idea conveyed by the Second Law is that while energy is never created or destroyed, energy is gradually dispersed, becoming less and less useful. Engines use concentrated energy - fuel - to operate. The end product is waste heat - too dispersed for it to be recaptured and re-used. Indeed, the very act of trying to do that would be self-defeating, incurring a greater energy cost than that recouped. Entropy - the spontaneous tendency for systems to become chaotic, more dispersed, has been successfully analysed statistically in terms of order/disorder, more specifically to do with numbers of possible arrangements. The example I used to give students was this. Imagine you have a neat and tidy bedroom, and there's a strong gust of wind through an open window. Papers get scattered, things fall off shelves etc. Suppose one started with a disordered bedroom, and there was a gust of wind. You would be very surprised if you ended with a tidy bedroom. The probability of a chance event - in this case the wind - producing disorder is hugely greater than that of producing order. Why? Because there are relatively few ordered arrangements compared to the number of disordered ones.
What's all this got to do with cosmology you may ask? Well, we see entropy increase around us on a daily basis - eg salt dissolves in water. The ordered structure of a crystal is replaced with the chaos of dispersed ions in solution. If entropy is steadily increasing, in accordance with the Second Law, then the entropy of the initial singularity must presumably have been minimal, possibly zero - a maximally-ordered system it would seem.
There's a problem, then, with the idea of contraction back to a singularity - the Big Crunch. Why ? Because if the end result is the same singularity, then entropy would decrease steadily during the contraction. But that would be contrary to the Second Law, would it not? Other objections have been raised. If we lived in a contracting universe, salt would presumably still dissolve in water, so we would still be seeing the Second Law in action.
Some have tried to get round the conundrum by introducing the variable of time. It then gets very counter-intuitive, especially the concept of negative time, even history running in reverse! Let's not go there.
I believe there is a way of reconciling the concept of a Big Crunch with entropy and the Second Law.
I shall be posting it here tomorrow!
Wed 21 Oct: Well, tomorrow has arrived, so here's the rest of the story.
It's all to do with the size of the Universe, and its fitness or otherwise to act as an entropy-increasing heat sink. While the Universe is expanding, there is abundant space in which heat can dissipate, or other forms of disorder can occur - eg dilution of gaseous end products etc. In the initial stages of contraction, things would continue much the same while there are still light-years between galaxies, or light-minutes between planets and their nearest neighbours, or even light-seconds between a planet and its moon with intervening space.
But imagine the process of contraction occurring continuously. There will finally come a time when one's perception of nature will change. Galaxies will collide for a start, but let's focus on events at a more local level. Previously there was almost limitless space for heat to dissipate. That will no longer be the case - for two reasons. First there is less space for any new heat to dissipate. Secondly, and more importantly, all the previous heat dissipated into the Universe - which is still out there- will become progressively concentrated. (Reminder; it's not just the contents of space that disappear into a black hole vortex - but the fabric of space-time itself- represented by the mesh in the graphic).
Temperatures in deep space, presently a few degree above absolute zero, will start to increase. The so-called microwave background radiation, a left-over from the Big Bang - will gradually shift and start to shorten in wavelength - first to normal radio frequencies, and then into the infra-red region. That's when things start to get interesting. Engines will no longer run so efficiently, because as background temperatures rise, they will find it progressively harder to dissipate exhaust heat.
Let's now look at the salt/water system. Yes, salt will continue to dissolve in water, suggesting that all is well - that the Second Law is still operating. But as background temperatures increase, the water gets hotter, and if there were still observers around, a point would be reached when the water was no longer liquid at normal temperatures and pressures. In other words, salt could not dissolve in water - if there were no liquid water still in existence!
So there would in fact be a gradual violation of the Second Law as we know it, were the Universe to implode towards a Big Crunch, due to increasing difficulty in dissipating waste heat against a background of rising temperature. In the final stages, the temperatures would become so great that no heat could be dissipated at all. In that situation, one has returned to a state of minimum entropy, but hugely elevated temperatures.
Had a classical thermodynamicist such as Carnot (of eponymous cycle fame) been born into a contracting Universe he would have enunciated the Second Law of Thermodynamics differently, methinks. Quite how it would have been worded I would not care to speculate, except to say it would need to have been heavily qualified re differences between open and closed systems. Could a contracting Universe even be described as "open". Only when the system under study was small, with a sizeable temperature difference between it and everything else "out there"?
What then? See my earlier ideas in the margin (scroll down) which have now been appeared in the MSM - so far with no serious objections being raised. I do not believe that the Big Crunch continues indefinitely. There comes a point when, through frictional forces, the plasma reaches the maximum possible temperature - when its constituent particles (strings?) then moving/vibrating so rapidly that they reach the speed of light, and then transform into massless photons. When that occurs, the system ceases to be a superblack hole, and spectacularly flies apart, creating a new Big Bang...
Update 16th Dec 2014 (5 years later!)
It's temperature that is the key to the conundrum, and the kind of world it creates for those seeking evidence of order/disorder.
In our relatively low temperature world (relying on radiated heat from a single sun that is 92 million miles away) we see lots of evidence of order, notably as the presence of substances as liquids and solids, when at higher temperatures (say in the laboratory) they becomes gases, and at thousands or millions of degrees would be in the plasma state.
But the latter are the temperatures that attain when a Universe contracts down to a black hole, and then singularity, hypothetically or otherwise. So it's useless to go looking for the kind of ordered, low entropy signatures that we are accustomed to. We have to ask ourselves what the signatures are when temperatures are hugely elevated, such that subatomic particles are travelling at speeds close to those of light, and colliding with each other. Those collisions break down the order of associations, but progressively a simplified plasma emerges in which there are the ultimate particles only, whatever they happen to be, all crushed together. The original translational energy across sizeable distances now becomes progressively constrained to vibrations about fixed positions (as in a classical earthly solid), obviously with enormous oscillation frequencies. Thus a kind of high-temperature/highly ordered/low entropy state does (paradoxically perhaps) become finally achievable, but through initial fragmentation, rather than clumping association. In other words, there's more than one route to a low entropy state, depending on temperature.
Saturday, October 10, 2009
What went wrong with NASA's moon crash?
The idea was to crash a spacecraft into the Moon at a chosen spot where ice might be lurking. Hitting the Moon at twice the speed of a bullet would send a plume of debris miles high that could then be analysed spectroscopically for water.
But there appears to have been no plume - only a brief white flash. Why not? Here's this blogger's explanation for what it's worth, published first on New Scientist and now the Times.
From the latter:
"Maybe a plume was formed but settled too quickly to be seen by the following probe, 4 minutes behind. Don't forget that although gravity is lower on the Moon, making things slower to fall, there's no air to slow the descent - even of dust particles or those hoped-for ice crystals.
There's a classic lab experiment in which a stout glass tube has all the air pumped out. A feather inside then falls as quickly as a ball-bearing.
Let's hope the NASA scientists did not forget their school physics."
Update: Sunday 18 October Well, halleluja, a plume was captured on camera after all, although the photograph in New Scientist ("Elusive lunar plume caught on camera after all") was somewhat disappointing. I mean to say - given it was said to be 6-8 kilometres wide, why show us a mere smidgeon of white on a so-called "zoomed image"? Small wonder the conspiracy theorists began falling out of the woodwork!
The fact that a plume was briefly formed lends support to the hypothesis I've ventured above. The plume didn't last long, because the particles fell back faster than many might suppose (given that the Moon's lower gravity seems to dominate most thinking, with the absence of an atmosphere frequently overlooked).
The absence of an atmosphere alters the dynamics of an impact and its aftermath considerably. Dust and other particles (ice?) may well be ejected much higher and further than on Earth, due to absence of a cushioning atmosphere - no air molecules to be pushed aside- but their return to "earth" would look entirely different to an observer or camera. Initially the descent would seem gentle - due to 1/6th Earth's gravity- but acceleration would be continuous, without anything comparable to "terminal velocity" (approx 120 mph on Earth in "old money"). A quick back- of- envelope calculation using school physics says that while it would take some 30 seconds for dust or ice particles to reach 120mph (which is our earthly terminal velocity), they would go on accelerating indefinitely until they finally hit the surface. There's another factor to consider - which another scribe on NS comments has pointed out : much of the ice -if present- would be vaporised by the kinetic energy (heat) of impact. The molecules would be unlikely to re-coalesce in the Moon's near-vacuum, and simply disappear from view - except perhaps to a highly sensitive spectrometer that was set up specifically to look for them - and certainly fail to drop back. Molecules generally don't "drop back" in a vacuum, especially in a weak gravitational field. They would simply spread out, ie diffuse rapidly.
But there appears to have been no plume - only a brief white flash. Why not? Here's this blogger's explanation for what it's worth, published first on New Scientist and now the Times.
From the latter:
"Maybe a plume was formed but settled too quickly to be seen by the following probe, 4 minutes behind. Don't forget that although gravity is lower on the Moon, making things slower to fall, there's no air to slow the descent - even of dust particles or those hoped-for ice crystals.
There's a classic lab experiment in which a stout glass tube has all the air pumped out. A feather inside then falls as quickly as a ball-bearing.
Let's hope the NASA scientists did not forget their school physics."
Update: Sunday 18 October Well, halleluja, a plume was captured on camera after all, although the photograph in New Scientist ("Elusive lunar plume caught on camera after all") was somewhat disappointing. I mean to say - given it was said to be 6-8 kilometres wide, why show us a mere smidgeon of white on a so-called "zoomed image"? Small wonder the conspiracy theorists began falling out of the woodwork!
The fact that a plume was briefly formed lends support to the hypothesis I've ventured above. The plume didn't last long, because the particles fell back faster than many might suppose (given that the Moon's lower gravity seems to dominate most thinking, with the absence of an atmosphere frequently overlooked).
The absence of an atmosphere alters the dynamics of an impact and its aftermath considerably. Dust and other particles (ice?) may well be ejected much higher and further than on Earth, due to absence of a cushioning atmosphere - no air molecules to be pushed aside- but their return to "earth" would look entirely different to an observer or camera. Initially the descent would seem gentle - due to 1/6th Earth's gravity- but acceleration would be continuous, without anything comparable to "terminal velocity" (approx 120 mph on Earth in "old money"). A quick back- of- envelope calculation using school physics says that while it would take some 30 seconds for dust or ice particles to reach 120mph (which is our earthly terminal velocity), they would go on accelerating indefinitely until they finally hit the surface. There's another factor to consider - which another scribe on NS comments has pointed out : much of the ice -if present- would be vaporised by the kinetic energy (heat) of impact. The molecules would be unlikely to re-coalesce in the Moon's near-vacuum, and simply disappear from view - except perhaps to a highly sensitive spectrometer that was set up specifically to look for them - and certainly fail to drop back. Molecules generally don't "drop back" in a vacuum, especially in a weak gravitational field. They would simply spread out, ie diffuse rapidly.
Labels:
moon crash,
NASA,
search for lunar water
Thursday, October 8, 2009
The Times "Eureka" magazine - first impressions
I've just spent an hour leafing through the Times's most recent addition to its publishing platform. It's called Eureka, its cover is very green, with an unattractive graphic of a chap who's lost the top half of his skull, with a plethora of sciencey things bursting forth from the exposed remainder.
Personally I find it hard to conceive of an image that is better guaranteed to confirm in the layman's mind that science is a nerdy thing that reveals more than you really want to know - an autistic lack of the light touch, to say nothing of discretion and good taste .
Well, I hadn't intended to start on so negative a note, but it's sitting there next to me in all its disturbing, stomach-churning immediacy, so I want to get that off my chest. First impressions still count, do they not?
Second and subsequent impressions are a lot more favourable. One doesn't envy anyone the task of producing a digest of science for the general reader of a newspaper, not even a serious one like The Times. How does one define the target audience, given that a relatively small proportion will have formal scientific qualifications much beyond GCSE - or O-Level? Then there is the notorious antipathy that exists towards science and scientists in the UK - one that has produced what someone described some years ago as the "ghettoization" of science.
Scientists are partly to blame themselves - let's not go into all that right now. Suffice it to say that the finger hovers over the remote when a science programme appears on TV. Woe betide any presenter who attempts to get too immersed in detail, or who overdoes the gee-whizzery, pie-in-the-sky delivery. The British public is inured to that kind of thing, and is likely to say "Come back in 10 years when you know some more, or have a workable, marketable product."
The criterion for a good thriller is that it is un-putdown-able. So what should it be for a periodical that appears only once a month? Not un-putdownable - that would be asking too much, in view of the subject matter. I suggest it should be put-downable, ie nothing too long and demanding of time, but so pick-uppable again that it escapes an early fate in the nether regions of a bulging paper-rack, or worse still the dustbin. In that sense I believe "Eureka" is over its first hurdle. There's a good mix of light and serious, human and technical, visionary and realistic to make it worth returning to if one only has the time or inclination to dip in now and again.
I'll come back in a day or two with a closer look at some of the features. I do have one or two quite serious gripes with some of the detailed science. In particular the feature "Living in the City" seems to have some unrealistic chemistry and biology. Since when has carbon dioxide reacted with magnesium chloride to give magnesium carbonate? (The reaction proceeds fine in the opposite direction!) But let's not nitpick today. The line-up of writers is impressive - with at least three with solid research experience and qualifications - up to and beyond PhD - and amazingly the Times has secured the services of Martin Rees - President of the Royal Society- whose keynote contribution is worth a read, touching as it does on a host of the issues that confront scientists, and the perception (or misconceptions) re the scientific approach to modern life and the myriad questions it throws up.
Update: Friday 9 October
The individual articles in Eureka are now online, including the one with the questionable chemistry. Have submitted this comment:
"Hmmm. While one welcomes "out-of-the-box" thinking on technology, the fundamental science has to stay firmly within the box.
It would not seem feasible, for example, to use "magnesium chloride" as a trapping agent for CO2. Magnesium hydroxide, certainly, but since that's made from magnesium carbonate, heating in steam to drive off CO2, it's self defeating re carbon footprints.
With magnesium chloride, one is trying to make the following (well known) reaction go in reverse:
magnesium carbonate + hydrochloric acid -> magnesium chloride + water + carbon dioxide
Not only does it prefer to go in the direction shown, but if one did contrive conditions to make it go in reverse one would release hydrochloric acid fumes into the neighbourhood! Hardly environmentally-friendly!
The bacterial illumination look improbable too. Yes, there are strains that react oxygen with luciferin, but the light-show is mediated by the enzyme luciferase, and that catalysis, like the rest of bacterial metabolism, requires an aqueous environment. I doubt whether bacteria would take kindly to being incorporated into coatings if that meant having to exist lichen-like in all weathers. Bacteria - excluding their resistant spores- are a lot more fussy about their environment!"
Personally I find it hard to conceive of an image that is better guaranteed to confirm in the layman's mind that science is a nerdy thing that reveals more than you really want to know - an autistic lack of the light touch, to say nothing of discretion and good taste .
Well, I hadn't intended to start on so negative a note, but it's sitting there next to me in all its disturbing, stomach-churning immediacy, so I want to get that off my chest. First impressions still count, do they not?
Second and subsequent impressions are a lot more favourable. One doesn't envy anyone the task of producing a digest of science for the general reader of a newspaper, not even a serious one like The Times. How does one define the target audience, given that a relatively small proportion will have formal scientific qualifications much beyond GCSE - or O-Level? Then there is the notorious antipathy that exists towards science and scientists in the UK - one that has produced what someone described some years ago as the "ghettoization" of science.
Scientists are partly to blame themselves - let's not go into all that right now. Suffice it to say that the finger hovers over the remote when a science programme appears on TV. Woe betide any presenter who attempts to get too immersed in detail, or who overdoes the gee-whizzery, pie-in-the-sky delivery. The British public is inured to that kind of thing, and is likely to say "Come back in 10 years when you know some more, or have a workable, marketable product."
The criterion for a good thriller is that it is un-putdown-able. So what should it be for a periodical that appears only once a month? Not un-putdownable - that would be asking too much, in view of the subject matter. I suggest it should be put-downable, ie nothing too long and demanding of time, but so pick-uppable again that it escapes an early fate in the nether regions of a bulging paper-rack, or worse still the dustbin. In that sense I believe "Eureka" is over its first hurdle. There's a good mix of light and serious, human and technical, visionary and realistic to make it worth returning to if one only has the time or inclination to dip in now and again.
I'll come back in a day or two with a closer look at some of the features. I do have one or two quite serious gripes with some of the detailed science. In particular the feature "Living in the City" seems to have some unrealistic chemistry and biology. Since when has carbon dioxide reacted with magnesium chloride to give magnesium carbonate? (The reaction proceeds fine in the opposite direction!) But let's not nitpick today. The line-up of writers is impressive - with at least three with solid research experience and qualifications - up to and beyond PhD - and amazingly the Times has secured the services of Martin Rees - President of the Royal Society- whose keynote contribution is worth a read, touching as it does on a host of the issues that confront scientists, and the perception (or misconceptions) re the scientific approach to modern life and the myriad questions it throws up.
Update: Friday 9 October
The individual articles in Eureka are now online, including the one with the questionable chemistry. Have submitted this comment:
"Hmmm. While one welcomes "out-of-the-box" thinking on technology, the fundamental science has to stay firmly within the box.
It would not seem feasible, for example, to use "magnesium chloride" as a trapping agent for CO2. Magnesium hydroxide, certainly, but since that's made from magnesium carbonate, heating in steam to drive off CO2, it's self defeating re carbon footprints.
With magnesium chloride, one is trying to make the following (well known) reaction go in reverse:
magnesium carbonate + hydrochloric acid -> magnesium chloride + water + carbon dioxide
Not only does it prefer to go in the direction shown, but if one did contrive conditions to make it go in reverse one would release hydrochloric acid fumes into the neighbourhood! Hardly environmentally-friendly!
The bacterial illumination look improbable too. Yes, there are strains that react oxygen with luciferin, but the light-show is mediated by the enzyme luciferase, and that catalysis, like the rest of bacterial metabolism, requires an aqueous environment. I doubt whether bacteria would take kindly to being incorporated into coatings if that meant having to exist lichen-like in all weathers. Bacteria - excluding their resistant spores- are a lot more fussy about their environment!"
Labels:
Martin Rees,
Times Eureka
Friday, September 25, 2009
That so-called "Anglo-Saxon" treasure could have been of genuine British-manufacture
I'm going to stick my neck out here. Who's to say that the fabulous hoard of gold and silver craftwork, unearthed by that bloke with the metal detector in Staffordshire, was produced by Johnny-Come-Lately Anglo-Saxon settlers?
OK, so we are supposed to be proud of our admixture of Anglo-Saxon and other genes. We are supposed to take pride in being an allegedly mongrel race (hybrid vigour an' all).
But have your read your Stephen Oppenheimer? He's the Oxford scholar who analyses modern DNA to trace our genetic roots. I blogged about his claims some 3 years ago. Oppenheimer rejects the idea that Anglo-Saxons supplanted the native Brits, sending us scurrying to the Celtic fringes. Oppenheimer reckons that the native Brits pre-dated the Celts, and indeed resisted numerous waves of invasion - the Celts, the Romans, the Anglo-Saxons, the Normans, stubbornly staying put, and surviving - either by putting up resistance, or by assimilating the invaders.
Oppenheimer reckons that native Brits are derived from Basque migrants who recolonised Britain some 15,000 years ago after the last Ice Age, crossing the then still existing land bridge between the Continent and England.
So why is the treasure being described as Anglo-Saxon? Who's to say it is not native British - or, less probably, Celt?
OK, so it was discovered in a Staffordshire field, in central England, and is reckoned to be 7th century, when that part of England was in the Anglo-Saxon kingdom of Mercia. But that does not mean that it was Anglo-Saxon treasure. It may have been of native British manufacture, possibly from the era (mythical or otherwise) of King Arthur, Camelot, and the Knights of the Round Table. It may have been taken from our dead warriors on the battlefield as war booty - or maybe our knights buried their finery (purely for show!) before facing the invader in battle wearing the equivalent of combat fatigues.
What's the evidence that Anglo-Saxons ever produced such exquisite artwork? I thought they were practical types, more concerned with clearing forest, ploughing, agriculture and animal husbandry? Their efforts went into producing axes and ploughs - not fine gold filigree ornamentation.
Yep, I'll put my head on the block. The "experts" have got it entirely wrong. It's not Anglo-Saxon treasure. It's British treasure. And no, I don't mean Celtic treasure - although that gifted if mercurial folk did produce fine arts and crafts - and are arguably more highly regarded in that respect than the Anglo-Saxons.
Nope, I reckon the treasure was produced by native "aboriginal" Brits, of Basque-derived stock according to Professor Oppenheimer - the true Brits - the ones who re-settled the British Isles, and who have managed to survive and prosper despite waves of immigrants seeking a better life. Britain's geography permitted co-existence within probably quite confined geographical areas - a few hundred square miles for example - which could be a little as 20m x 20m- thanks to our varied topography, the (then) more abundant forest cover, and, dare I say it, mutual tolerance and/or respect between native and newcomer. There was room for everyone who was prepared to work, and to "live and let live" - the British way. Britain was, if you like, the "New World" of the first millennium, once the Romans had left.
I repeat: the experts may have got it wrong. One cannot assume it is Anglo-Saxon treasure. It could well have been the exquisite handiwork of native Brits who succeeded in maintaining their genetic, ethnic and cultural identity over thousands of years - standing firm and finally expelling - or assimilating- the Celts, Romans, Anglo-Saxons, Danes, Vikings and Normans.
Update Sat 26 14:31 : See the Telegraph article with its 23 comments - at the time of writing.
The "Staffordshire Hoard" now has a wikipedia entry
Just 9 of some 1500 so-called "Anglo-Saxon" artefacts - a stupendous find, regardless of provenance
OK, so we are supposed to be proud of our admixture of Anglo-Saxon and other genes. We are supposed to take pride in being an allegedly mongrel race (hybrid vigour an' all).
But have your read your Stephen Oppenheimer? He's the Oxford scholar who analyses modern DNA to trace our genetic roots. I blogged about his claims some 3 years ago. Oppenheimer rejects the idea that Anglo-Saxons supplanted the native Brits, sending us scurrying to the Celtic fringes. Oppenheimer reckons that the native Brits pre-dated the Celts, and indeed resisted numerous waves of invasion - the Celts, the Romans, the Anglo-Saxons, the Normans, stubbornly staying put, and surviving - either by putting up resistance, or by assimilating the invaders.
Oppenheimer reckons that native Brits are derived from Basque migrants who recolonised Britain some 15,000 years ago after the last Ice Age, crossing the then still existing land bridge between the Continent and England.
So why is the treasure being described as Anglo-Saxon? Who's to say it is not native British - or, less probably, Celt?
OK, so it was discovered in a Staffordshire field, in central England, and is reckoned to be 7th century, when that part of England was in the Anglo-Saxon kingdom of Mercia. But that does not mean that it was Anglo-Saxon treasure. It may have been of native British manufacture, possibly from the era (mythical or otherwise) of King Arthur, Camelot, and the Knights of the Round Table. It may have been taken from our dead warriors on the battlefield as war booty - or maybe our knights buried their finery (purely for show!) before facing the invader in battle wearing the equivalent of combat fatigues.
What's the evidence that Anglo-Saxons ever produced such exquisite artwork? I thought they were practical types, more concerned with clearing forest, ploughing, agriculture and animal husbandry? Their efforts went into producing axes and ploughs - not fine gold filigree ornamentation.
Yep, I'll put my head on the block. The "experts" have got it entirely wrong. It's not Anglo-Saxon treasure. It's British treasure. And no, I don't mean Celtic treasure - although that gifted if mercurial folk did produce fine arts and crafts - and are arguably more highly regarded in that respect than the Anglo-Saxons.
Nope, I reckon the treasure was produced by native "aboriginal" Brits, of Basque-derived stock according to Professor Oppenheimer - the true Brits - the ones who re-settled the British Isles, and who have managed to survive and prosper despite waves of immigrants seeking a better life. Britain's geography permitted co-existence within probably quite confined geographical areas - a few hundred square miles for example - which could be a little as 20m x 20m- thanks to our varied topography, the (then) more abundant forest cover, and, dare I say it, mutual tolerance and/or respect between native and newcomer. There was room for everyone who was prepared to work, and to "live and let live" - the British way. Britain was, if you like, the "New World" of the first millennium, once the Romans had left.
I repeat: the experts may have got it wrong. One cannot assume it is Anglo-Saxon treasure. It could well have been the exquisite handiwork of native Brits who succeeded in maintaining their genetic, ethnic and cultural identity over thousands of years - standing firm and finally expelling - or assimilating- the Celts, Romans, Anglo-Saxons, Danes, Vikings and Normans.
Update Sat 26 14:31 : See the Telegraph article with its 23 comments - at the time of writing.
The "Staffordshire Hoard" now has a wikipedia entry
Thursday, September 24, 2009
No genuinely free water on the Moon, it would seem...
The ambiguity of "free" in my title is deliberate. The traces of water detected by that inspired Indian lunar probe are not of course free water, in a chemical sense, but chemically-bound, non-wettening "water".
Even my non-scientific wife was quick to realize that, watching last night's news, even if the media reports elsewhere conjure up visions of future moon colonists tapping into an abundant supply. Moonshine!
Being chemically-bound, whether weakly or strongly, it's hardly free for the taking either. The expression "getting blood out of a stone" springs to mind.
Here's what I sent last night to the Times in response to that trumpeting headline re there being a litre of water per tonne of lunar soil. (One feels that "water" should have been enclosed in quotation marks in the Times's article).
Is that a water-diviner in his hand? If so, then happy-hunting..
Being chemically-bound, whether weakly or strongly, it's hardly free for the taking either. The expression "getting blood out of a stone" springs to mind.
Here's what I sent last night to the Times in response to that trumpeting headline re there being a litre of water per tonne of lunar soil. (One feels that "water" should have been enclosed in quotation marks in the Times's article).
September 24, 2009 11:10 PM BST on community.timesonline.co.uk
"Hydroxyl", note, is not a molecule, as the report would have one believe. Being simply OH, with an unpaired electron, it would be a free radical, with no independent existence, and a lifetime of seconds at most if generated in the atmosphere by, say, cosmic ray bombardment. Most "OH" in rocks is, of course, present as negatively-charged hydroxyl ions, accompanying positively-charged metal ions, eg aluminium.
Aside: well done, btw, Times for finally adding a time and date stamp to readers' comments, and for a much-speedier moderation than before. The BBC-style facility for expressing approval is also cute. It even survives cut-and-pasting here, apparently as a live-link - see the blue font above! Shame though that one's comments are not accessible to search engines. The world wide web depends on linking, you know, if only for information-retrieval. Vanity has nowt to do with it, of course...
Update: Friday 15:15 pm. Had some further thoughts on the inconclusive nature of the chemistry after reading the New Scientist's feature: Have just sent the following:
"Hmmm. So the signal could have come from water or from the "OH molecule". Leaving aside the faulty nomenclature - OH is not a molecule, but is either a free radical if electrically neutral, or a negatively- charged ion - it seems a bit of a liberty to lump together two entirely different chemical species in this manner. The discovery of H2O would indeed be exciting, even if strongly adsorbed to minerals. But "hydroxyl", presumably as mineral hydroxides, would be an entirely different matter, requiring somewhat high temperatures in most cases if desiring to drive off molecular water, which would then have to be cooled and condensed. Most of the hydroxides of predominant minerals in the Earth's crust - magnesium, calcium, aluminium etc- hang onto their oxygen and hydrogen quite firmly, needing red heat or higher to dissociate into oxides and steam.
So it's somewhat premature surely to report that "water" has been discovered. On the basis of available evidence, none of which can be described as "hard", what's been discovered are oxygen atoms that are bonded to one or possibly two hydrogen atoms with a strong attachment to a mineral matrix given they are able to survive solar heating in a vacuum. Alternatively, and less usefully from the point of view of harvesting lunar water, the signal is picking up a temporary association, ie the turnover model, which would explain why the discovery did not come earlier from study of Apollo-mission rocks"
Update Sep 25 21:17 : See also "How could astronauts harvest water on the Moon" - latest article in New Scientist.
Update: Friday 15:15 pm. Had some further thoughts on the inconclusive nature of the chemistry after reading the New Scientist's feature: Have just sent the following:
"Hmmm. So the signal could have come from water or from the "OH molecule". Leaving aside the faulty nomenclature - OH is not a molecule, but is either a free radical if electrically neutral, or a negatively- charged ion - it seems a bit of a liberty to lump together two entirely different chemical species in this manner. The discovery of H2O would indeed be exciting, even if strongly adsorbed to minerals. But "hydroxyl", presumably as mineral hydroxides, would be an entirely different matter, requiring somewhat high temperatures in most cases if desiring to drive off molecular water, which would then have to be cooled and condensed. Most of the hydroxides of predominant minerals in the Earth's crust - magnesium, calcium, aluminium etc- hang onto their oxygen and hydrogen quite firmly, needing red heat or higher to dissociate into oxides and steam.
So it's somewhat premature surely to report that "water" has been discovered. On the basis of available evidence, none of which can be described as "hard", what's been discovered are oxygen atoms that are bonded to one or possibly two hydrogen atoms with a strong attachment to a mineral matrix given they are able to survive solar heating in a vacuum. Alternatively, and less usefully from the point of view of harvesting lunar water, the signal is picking up a temporary association, ie the turnover model, which would explain why the discovery did not come earlier from study of Apollo-mission rocks"
Update Sep 25 21:17 : See also "How could astronauts harvest water on the Moon" - latest article in New Scientist.
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Why not get the Sahara green first - to create biomass and reduce CO2? Huge problems to overcome, yes, but if we can't lick that problem, what hope is there of colonising the Moon or Mars on a realistic timescale?