Thursday, December 6, 2012

They're just not that into us



Well, for a while I was pretty upset.  This was my first reaction:

 
Then I was *sure* it was a typo, because of what was written in the 03 section report; and then I figured out it wasn’t, and got really upset.  Luckily instead of dabbling further in ‘career-destroying tweet’ waters, I went off and gunned down a bunch of Egyptian cultists

You see, I consider the 2012 ERA rankings a *personal* smack-down and humiliation because I was the one who was crankiest about us not submitting anything last time around and falling off the radar, who pushed hardest for going in this year, was most confident that the assessors would see through any spin and hype to the bone and sinews beneath, and most confident that we could and would make a 3.  

But I have reached a kind of equilibrium.  There are lots of people who have suffered worse. St. Sebastian, for instance:  

And I am a contrarian who always regarded the whole process with caustic cynicism, so it is not like I have any starry-eyed illusions about the results being objective or having any intrinsic meaning.

More importantly, I have realised that what is being measured as ‘research quality’ has nothing to do with what we in a university fulfilling the traditional functions of a university consider to be ‘research quality’.

In a publicly-funded university that has a legally mandated mission to deliver the ‘whole of knowledge’ to its community, we believe that the interests of our academic staff in chemistry should cover the ‘whole of chemistry’.  We think that every potential PhD candidate interested in any branch of chemistry should be able to do their PhD with a respected chemist and publish work of internationally-recognised quality. We think this is in the best interest of our students and the best interests of the nation.

The ERA exercise would clearly be happier if all our students and all our resources were funnelled to one high-flier publishing in one field so we could meet a totally arbitrary cut-off of number of papers for a four digit 03** code. But that is the opposite of what we’re about.  I suppose that means by the ARC’s lights that we see research as subordinate to teaching. If so, so be it. Teaching is the rationale for our existence.  

Saturday, September 29, 2012

What's not to like?



It is the greatest happiness of the greatest number that is the measure of right and wrong.  
(Jeremy Bentham)




It was an impulse buy. Sandy had given up on those sort of gimmicks a long time ago. Once or twice a year self-loathing would goad her into a calorie-controlled diet, but lack of visible results and the impossibility of coping with work while feeling hungry all the time meant she could never stick at it for long. As for miracle weight loss products, fad diets, and programmes, she had long since stopped paying attention.

It was the woman on the box that did it. She looked so genuinely happy. Sandy couldn't remember the last time she had seen anyone - in real life, on TV, or one of the perfect people plastered over every available advertising surface - who looked so utterly content and authentic in their consumer ecstasy. And it was on special. Half price.  'Choose happiness!'  it said in friendly letters underneath the woman's picture. 'If only' muttered Sandy sadly to herself, and without really thinking put the package of meal-replacement drinks in her trolley. It was a brand she had never seen before.

I don't blame Sandy. If it wasn't Sandy, it would have been somebody else. Or if no one had ever bought it, They would have found some other way.

The next day was Monday.  Sandy came home from work with her gut tied in knots  from what Tamika had said and slumped on the couch watching impossibly fit young people play tennis. She hated tennis but couldn't get up the energy to change the channel. She couldn't face making a proper dinner either, so she got one of the meal-replacement drinks. It was the sort of fine powder that gets everywhere no matter how carefully you try to open the packet, and that takes forever to stir to get rid of the lumps. She hardly tasted it at all. And it didn't make her feel like the woman in the picture.

At least, not until the next morning.

When the alarm went off, Sandy realised her bedroom was beautiful. In the pre-dawn, the contours of the junk on the bedside table looked like the towers of an alien city at sunrise, gleaming with mysterious potential. The fragment of poetry 'rose-red city half as old as time', which she had once seen on a poster in a travel agent's window, flamed into her thoughts. Then a vision of one of the cities in Ray Bradbury's 'Martian Chronicles', which she had read as a teenager, and a brief unbearable tang of bittersweet affection for the doomed Martians.  She swung herself out of bed. The knot of despair in her gut was gone. She felt no dread of the put-downs and petty nastinesses she was sure to face at work.  She felt good. The heavy pall of self-loathing that had hung over her constantly since she was fourteen years old was gone.

It was another rubbish day at work. Tamika and Marcella were even more vicious than usual. But today Sandy didn't seem to mind. Life was beautiful. She was happy. Instead of ending up weeping in the loo at lunchtime, she sat in the tearoom and looked out at the sunlight playing on the windswept leaves of the trees by the carpark. She had never noticed before how beautiful it all was. It wasn't until then that she thought just how strange it was that she felt so happy.

'If this is because of that stuff I had last night, there's no way it can be legal. This is crazy.' A mental image of a box labelled 'Uncle Arthur Conan Doyle's Heroin-Infused Bran Flakes' came to her, and she giggled. A voice - it sounded like Darren - said something that could only have been 'crazy fat bitch' from the other side of the room, and Sandy only felt a pang of bittersweet affection for him, like he was one of the doomed Martians.

That night she had The Dream.

She was walking with the woman from the package. Or flying, in that way dreams sometimes blur two things together that could never really be blurred together. In the same way the woman from the box was covered with tiny little kingfisher-blue feathers - or not - in the same ambiguous dream fashion.

'This is how you are meant to feel' the woman said. 'This is how people should be. How you felt before was a wrongness. A disease.'

'I get that' said Sandy. She had the sense that she and the woman were not alone, that there were more of the kingfisher-blue people walking or flying nearby, hundreds or thousands or millions of them.

'Would you like to feel like this forever?' asked the woman.

'Oh yeah' said Sandy. 'Oh yeah.'

Sandy stayed happy. Life stayed beautiful. At work, she found she could just smile sweetly at people who would have left her a sullen mass of self-hatred the week before.

By Friday morning, everything she tried on was too loose. She started weighing herself again and found she was rapidly losing weight. Not rapidly enough to be frightening -  to be, for instance, another symptom of a brain cancer that was also causing her strange euphoria - just nice. It was like the celebrities in the magazines whose 'baby bodies' miraculously melt away without leaving any dangling wattles of skin.

'If I feel sick - at all - I'll go to the doctor' she promised herself. 'There can't be anything wrong with me if I feel fine.'

Day by day she effortlessly shrank towards the socially most acceptable body shape for a woman of her age.

Two weeks after The Dream Sandy swam up out of sleep an hour before dawn. Her skin was tingling, trembling for joy, like the skin of women in soap commercials. Through her sleep-blurred eyes she saw that her arm was shiny. Opalescent. A little like kingfisher feathers. Startled, she moved her arm, and the shininess on it took flight, a cloud of little dancing motes. They scattered in the air and faded, leaving only the faintest sheen remaining on her arm. She got out of bed, her heart pounding hard. They were streaming off her everywhere like solar flares, more slowly than the initial flight from her arm, in long coiling patterns of wilful smoke that seemed to make their own way toward the door. It was terrifying, but beautiful. The tingling in her skin stopped, the last motes faded, and she wasn't shiny any more.

'I should see the doctor' Sandy said to herself. 'I must be going crazy.'

But when she had finished breakfast she had changed her mind to: 'If I have any more weird hallucinations like that, then I'm going to see the doctor.'

By that time, although no-one had realised it, there was already a Scanning Electron Micrograph of one of the motes, taken two days before by a palynologist at Victoria University. It was a faceted ellipsoid, with three axes of length approximately 21.3, 13.2, and 8.1 microns. The same objects had also been seen in semen samples from the stud ram 'Wairarapa Roger', which meant they had to be thrown away, and - in vast numbers - in the blood of a Miss Allanah Sanderson, whose childhood leukaemia had suddenly gone into remission.  Some of the objects from Miss Sanderson's blood sample were sent for further analysis, but by the time the results came back, events had moved on.

Forty-five minutes after Sandy got to work that day, the first social media exchange between two people who had dreamed slightly different versions of The Dream took place. I didn't notice it until I woke up - 6:18 pm New Zealand time - by which time it was all over the internet. And I didn't decide that the only hope for humanity was to nuke New Zealand for another two hours. But even if I had been Emperor of Earth, it probably wouldn't have worked. Those things were drifting in the ocean by then. Carried on planes to places all over the world. Burrowing deep in the subsoil.

That afternoon The Dream had come up in the tearoom at Sandy's work. Afternoon tea ended with a group hug.

That was a week ago. The only other people I know who rejected The Dream are my friend James, who is aspergers, and the Pakistani couple that run the Asian music store on Hollins Road. Even after They issued Their statement, making it perfectly clear what Their plans were,  and letting people know they were free to change their minds whatever they chose, 998 out of a thousand people have chosen happiness. The last time I checked Their manifesto had 870 million 'Likes'.

You get to live forever. You get to fulfill your potential to be happy all the time. The only downside is that your real flesh and blood body gets replaced by a community of free-willed nanites - all immortal, all happy like you, all happy to be your friends and help you out. They mimic the body you had before, except you never get sick. Or, you can change it. If you ask nicely, They'll give you wings. Or gills. Or any kind of frigging superpower compatible with the laws of physics. They've converted most of the soil into Themselves. They're working Their way down into the crust, rearranging it into a different kind of sentient happy nanite. Animals and plants - anything without free will - They're replacing those too. Abolishing suffering. No more tortured mice. No more caterpillars writhing with ichneumon wasp larvae in their guts. What's not to like? But I don't like it.

They've promised to keep enough of the old ecosystem going to provide all the necessities of life for Luddites like me and James as long as we live. But They already outnumber us quintillions to one. God knows what Their plans for the planet are after we're gone.

I just watched the video of Sandy telling her story for the ninth time. I can't help myself. She looks so happy. She looks so beautiful. Damn. Damn. Damn.


Notes: 
 

1. There are doubtless more prosaic ways to successfully mount a Grey Goo invasion, of course. This one has not just been invented for novelty value, but as a solution to some potential problems that might arise for the invaders in a world subject to real world physics.

In the real world, space is full of violent cosmic rays and any journeys between stars will take a very long time, so any object carrying the nanites from somewhere else will need to be well shielded, and hence relatively large - I am thinking at least the size of a beach ball - but not so large as to make a big obvious fuss coming down. It makes sense to me for this thing to get down to Earth's surface in one go, instead of dispatching tiny probes from its limited resources to brave the atmosphere individually.

Now, this beach ball contains some billions of sentient beings. They won't follow a prearranged plan, but work out things as they go along based on all the information they collect from us as they approach our planet. They will want to be careful to kickstart their propagation as quickly as possible, to avoid the chance of being noticed by these curious ape-descended creatures and possibly being nipped in the bud. And I think something they would be quite likely to do, given their initially limited resources and desire for speed, is to hijack an efficient terrestrial system for gathering energy and matter and replicating complex structures - i.e., something alive - rather than rolling out their own systems. There is no reason this would be particularly easy, no matter how advanced their science. They need to get a lot of information into a living organism; certainly quite a few of their people - maybe some highly specialised sorts of nanites that a lot of work has gone into; and it is quite likely that they might need significant amounts of some trace elements not common in Earth - in the initial stage of rapid propagation, when they control few living systems, these would be a limiting factor on their growth and it would make sense to supply a bolus of them to the initial host for distribution through the first several generations. The nanites have few resources at this narrow window in time: they are psychologically conditioned to scarcity from thousands of years of living in a beach ball. So they won't scatter a lot of baits around willy-nilly where most of them will be wasted and they might be picked up by curious ape-descended scientists. No, I think it makes good sense for them to minimise waste by putting a lot of effort into one really good bait, designed for the biochemistry of a particular species. And if their study of our electronic traffic suggests a way that they can ensure self-selection of an individual member of that species who can easily afford the excess metabolic load, and who will be pleasantly surprised rather than freaked out if they suddenly lose a lot of mass... ? What's not to like?


2. The story is actually set in New Zealand because I thought of the idea when I happened to be there some years ago. Of course, a beach-ball-sized meteorite is large enough to be interesting, so landing in a remote bit of deep ocean before heading to the nearest supermarket is a sensible strategy, which would make New Zealand a more likely starting place than most.


3. As I was writing, I was thinking of the 'I' in the story as a male Anglo in his early 20s, geeky not nerdy, named 'Luke' and living in Oldham in the UK. But you can feel free to imagine him/her as being whoever you like, living in any English-speaking country in that approximate time zone.






Tuesday, September 18, 2012

Aussie Aussie Aussie! Oi oi oi...

I am embarrassed to find today, in this comparison of commercial oat brans (Luhaloo et al., 1998, J.Sci. Food Agric., 76, 142), that our oat bran is (was) really lame compared to the Scandinavian oat brans. See, we have the lowest protein! The highest fat! And the lowest beta-glucan (the bit that's good for you)! So, be sure to chose imported Nordic oat brain over our dubious local product... :(


Update:  At least our barley beats out Yemen and Albania. W00t!

(Cubadda and Marconi, 2008, Ingredienti Alimentari, 7, 6)



Wednesday, July 11, 2012

Whatever

A Brief Restatement of the Obvious for a Clueless World


Item 1: The heat capacity of the ocean is big compared to the heat capacity of the atmosphere.


Item 2: The carbon dioxide capacity of the ocean is big compared to the carbon dioxide capacity of the atmosphere.


Item 3: Heat and mass transfer across the atmosphere/ocean interface are not independent and are not simple.

Personal experience re Item 3: I have spent a lot of the last six years trying to get my head around heat and mass transfer across the atmosphere/farm dam interface. 

3a: It is really not simple.

3b: Even a failed physicist like me can see that the semi-empirical models of it in the 'climate science' literature are dodgy-as.

3c: I have a model: it is too hard to test in farm dams so we have gone back to 44-gallon drums of water.
3c.i: We haven't got data good enough to test it in six months yet.
3c.ii: 44-gallon drums of water are simpler than the ocean.


Item 4: When I was an undergraduate, when we talked about the weather, we talked about strange attractors and the butterfly effect and the essential unpredictability of complex systems and the impossibility of drawing a line between weather and climate since they showed the same self-similar pattern on all scales. Now, for the entire lifetime of today's undergraduates, the world has been running around like a headless chook pretending the climate can be modelled by y = mx + b.  

Problem?

Monday, July 2, 2012

Ce qu'on voit et ce qu'on ne voit pas


Just floating a back-of-envelope calculation about 12C:13C ratios in different parts of what I am going to call the 'dynamic' carbon cycle: the bit where carbon is moving around a lot, leaving out both the slow deposition of fossil fuels and carbonates and the geological or anthropogenic processes that get them out of the ground again.

I've taken some numbers from one of many pictures of the carbon cycle available on Our Friendthe Interwebz, and shown them to scale the way the ancient Greeks would have, geometrically. The area of the arrows and the squares are to the same scale, showing the amount of carbon in each place and the amount moving from one place to another in the course of a year. There are three populations of carbon in this simplified picture: Biomass (plants and soil), the atmosphere, and the oceans. And the greatest of these is the ocean.



Note that we basically have a fast equilibrium (the atmosphere and biomass equilibrating rapidly, on the rough order of a decade to exchange half the carbon in the biomass) and a slow equilibrium (the atmosphere and the ocean doing the same on the order of a few hundred years).

Before moving on, I just want to say that the overall ratio of 12C:13C in this whole system should remain pretty much the same for periods of geological time that are long compared the time scales in which lots of interesting things can happen. Good evidence for this is that the amount of variation in carbonates laid down since the beginning of the Pliocene is not very much at all: less than +/- 1 ‰ (Ghosh & Brand 2003).

Now, the relative amount of 12C:13C in each box will be governed by two things:

(1) The relative amounts of 12C:13C in the box(es) it is in equilibrium with; and,
(2) Any isotopic selectivity in the transitions between boxes.

Now, the isotopic selectivity due to the more rapid diffusion of  44CO2 over 45CO2 through eensy-weensy membranes in plants is very well understood: and this generates a clear difference in the 12C:13C ratio between biomass and the atmosphere, despite the rapid interchange between them.

But, if there was no life on Earth, the atmosphere would still be enriched in 12C:13C relative to the ocean. Because there is also a solid basis for isotopic selectivity in the ocean:atmosphere equilibrium. Most of the carbon in the ocean is present as hydrogen carbonate ions in the deep ocean. To get to the surface, this material has to run a gauntlet of a layer of warm water hundreds of metres thick where calcium carbonate is stable. I haven't been able to find any decent data on isotopic dependence of hydrogen carbonate ion diffusion rates - just some molecular dynamics simulations that didn't find a significant difference* - but a priori, if you have a column of fluid some hundreds of metres high, surely the bottom of the column is going to be enriched in the component with a molar mass of 62 rather than 61.

Now it seems to be the because of the fast interchange between the biomass and the atmosphere, the relative distribution of carbon isotopes between the ocean and the total (biomass + atmosphere) component has to be governed by the slow equilibrium. And thus the main driver of the isotopic ratio in the atmosphere has to be the slow equilibrium. Yes? If you see a problem with this, let me know.

So: looking back at those boxes. And going back to that number from Ghosh & Brand 2003 and some other numbers. Taking -6 13C ‰ for the pre-industrial recent atmosphere and -25 13C ‰ for terrestrial biomass (Epstein 1969) gives an overall value of -20 13C ‰ for the (biomass + atmosphere) component. Now, if we have a 13C ‰ of 0 ± 0.8 for oceanic carbonates since the Pliocene, this means that the error we should reasonably associate with this component should be of order ± 10 13C ‰.

This may be a conservative overestimate: but looking at the size of the boxes where the carbon is sitting, the error in the small boxes has to be bigger than the error in the small boxes. And there is one more small problem, which is that while the 12C:13C selectivity in plants is well-understood and not likely to have changed much at all since the little fellers evolved their carbon fixation pathways, the 12C:13C selectivity of ocean:atmosphere transport ought to be dependent on the distribution of the layer of warm water, which will rely on the vicissitudes of global climate and over a longer period of time how the continents are shifting about to change global ocean circulation.

So, my point is: relying on 12C:13C ratios alone to tell us details about the source of a particular carbon-containing deposit at some remote period of time is probably not a good idea, because there are likely to be big systematic errors which we know not what of.

Perhaps that's not a very big point. 




* And only just found a significant difference for CO2, where we know one exists experimentally.

Wednesday, June 27, 2012

My Little Planet: Interfaces are Magic


Okay, I've finished Thomas Gold's "The Deep Hot Biosphere" and have decided that I'm not quite ready to shout 'Eureka!' and say that this will be the continental drift of the 21st century.

Overall the chemistry seems pretty solid, and the model makes sense in terms of the likely process of planetary evolution, but I need to wander off and check some more recent primary references. Most intriguing is the information about helium and heavy metal distribution in hydrocarbons, which really doesn't seem to have any good explanation in terms of the traditional biotic origin theory. On the other hand I've thought of a perfectly good alternate explanation for the lack of isotopic drift in oceanic carbonate deposits over geological time – I'm sure you can do the same, so I won't tell you now. And Gold's explanation of methane clathrates doesn't seem to square with our current understanding of their distribution. So as I said, I have decided I'm not quite ready to jump on the bandwagon.

(Note the extreme sketchiness of my treatment here – this is because I want you to read the book yourself so we can talk about it, rather than spend my time making an exhaustive book report.)


Anyhow.


What I really want to do is to step back a little and discuss the implications of Gold's model for the origins of life in a more focussed way than he does in his Chapter 9. I say step back a little, since I'm not going to assume that Gold's model of upwelling of abiotic hydrocarbons is occurring on Earth now, or necessarily occurred in the past. What does seem plausible – so plausible that it is certain to have happened many, many, many times – is that such a model system has arisen on rocky planets somewhere. We know the clouds of junk available for making planets can contain a lot of carbonaceous material. The cold aggregation of an Earth-sized planet containing a lot of this material is sure to happen sometimes. The timeframe for outgassing of this carbonaceous material is sure to have extended over very long time periods on some worlds. As Gold postulates, it is sure that on some worlds there will have been a persistent water-rich layer on top of this hydrocarbon layer.

This plausible persistent environment is exciting. It is by far the best postulated locale for the development of life, or of pre-life, that I have come across.

Remember what we need:

We need to assemble a collection of complex molecules in something with an edge to it, so the collection can get more complicated inside that surface; we need a flux of energy into the system; and we need a flux of matter in and out of the system:a proto-proto-proto-proto-metabolism of some kind.

This all seems far more likely in the upwelling hydrocarbon system than any other possible system I have read about.

1. The upward flow of hydrocarbon material provides a source of chemical energy, a steady replenishment of raw material ('food') and a means of disposal of superfluous matter ('waste'). This is not going to be the case at all in the traditional 'small tidal pool' or a homogeneous cloud of dense molecular gas. The energy flux is going to be far more useful than the heat gradient one might get a large body of water, or in a small dense body like a comet, and the mass flux will be more persistent than any mass flux driven by these heat gradients.

2. As Gold stresses, and as he shows in a splendid figure from a paper by one of his Soviet precursors , complex molecules are much more stable at very high pressures. This means the necessary molecular complexity is much more likely to be present under such conditions.

3. Furthermore, the heterogeneous environment of the deep underground is fantastically more suited for complexification than something like an ocean, which is a pretty well-mixed homogeneous fluid. There are pores of different sizes; there are interfaces everywhere, with different adsorption characteristics on different minerals; there are thermal and chemical gradients. It is a chromatography column on a planetary scale providing an incredible opportunity for sorting molecules into a gazillion different microenvironments. There is nothing like this in any of those other possible environments for pre-biotic evolution. Gold makes much of the greater volume available for experimenting with chemistry underground than in the ocean, but does not mention this incredible advantage in terms of its partitioning into innumerable separate experiments.

4. At this point Gold wanders off the point and wastes the rest of Chapter 9 talking about numbers with large powers of ten – as people who talk about the origin of life are wont to do – and about autocatalytic reactions. You should know by now what I think about autocatalytic reactions and their irrelevance to the  more important questions of the origin of life, so I won't beat that dead horse just now.

What Gold could have done instead is consider some other implication of one other part of his model. He postulates that a layer dominated by hydrocarbons lies deep in the crust, beneath a higher layer dominated by aqueous solutions. What happens when they meet one another?

4a. Well, they don't mix homogeneously. We have proverbs about that.

4b. The water layer is relatively full of oxidants, so some of the large hydrocarbon molecules are partially oxidised. This can make them surface-active. Which means they will want to stay at the interface between the hydrocarbon and aqueous phases.

4c. As more surface-active material is generated, it will generate more interface for itself to sit at. That's what surfactants do. The interface will grow more complicated and interesting.

4d. As more surface-active material is generated, it will self-assemble into interesting structures. That's another thing surfactants do. Among the self-assembled structures they are likely to form are vesicles, the basis for all biological compartmentalisation we know about.

Voila, we have a persistent zone of CHO(N)-rich molecules and plausible proto-proto-cellular menbranes at the interface between the hydrocarbon world and the water world, eminently susceptible to further complexification!

This gives a strong pointer towards where we should be seeking the chemical building blocks of pre-pre-life: What do we get in reactions of hydrocarbon mixtures and oxidising aqueous solutions at very high pressures? And then, what do the phase diagrams of surfactant molecules formed in this way look like at the same very high pressures?


Even if Gold's theory turns out to be bogus as far as Earth is concerned, I am sure that it happened somewhere, and if it did, it could give rise to persistent complexifiable chemical systems: systems which, being embedded in very large lumps of matter, would be far more likely to survive fortuitous transport from one solar system to another than analogous systems somehow arising in gas clouds, planetary surfaces, or the interior of small cold bodies. So that's why I'm excited. :)



Edit June 30th: Also, this.

Tuesday, June 26, 2012

Aristotle, Dante, Dawkins, and a multi-millennial Arse-about-Face


Being an expansion of one of my two small points for expansion later

I am going to stick my neck out just this once, since life is too short to be timid. Carpe diem, and all that...

One of many ways our civilisation has parted ways with logic is that the 'anything goes, abort and experiment away' attitude to very small human beings is shamefully associated with a scientific worldview, while the 'don't do that' attitude is more usually than not explained away as an arbitrary theological idea, associated only with people with a strong religious worldview. This is exactly opposite to how it logically should be.
Allow me to explain.
I am going to make two assumptions to start with. Feel free to disagree with them. But if you do, be prepared to mount clear arguments upholding contrary assumptions against minds much wiser and subtler than mine.
1. Only individuals matter. Only individual entities can feel or suffer; only individual entities can have rights or obligations. Everything else is gravy, a second-order level of goods. Think of a Venn diagram of ideas showing where Simone Weil overlaps with Margaret Thatcher. This is it.
2. All non-trivial reasoning is probabilistic. If X causes Y, and Y causes Z, then X causes Z. If Z is bad, we stop X. Duh. But in the real world, there might be a 70% chance X causes Y if W is the case, but only a 20% chance if not-W, with some experts suggesting a very high chance of W and other experts suggesting a very low chance of W. Meanwhile, the high W experts also agree that there is a 70-90% chance that Y causes Z, with the low-W experts explaining at great length that Y has a best a 50% chance of causing Z. And Z might be bad. There's an 80% chance it is bad - say, a 10% chance it will be really bad - unless condition V is met, which is only about 10% likely, but would make Z really good... according to a sizeable minority of both W and non-W experts. So what should we do? That's my simple example of how we have to figure things out in the real world.
Now, to apply these two assumptions to the poorly-phrased question 'when does life begin?' which is not above the pay grade of anyone with a handful of neurons to stitch together into a crude neural net. The question is poorly-phrased, since 'life' began somewhere billions of years ago and ever since then the lives of individuals - the only important moral objects according to my assumption 1 - have been tangled together in complicated ways. What we are really asking is: When does a particular life become individuated enough from other life that it is worthy of moral consideration? Or, probabilistically, how much moral consideration should we pay to an individual life during the process of individuation, relative to the amount of consideration we pay to a fully individuated life?
I'm going to draw a graph showing the relative probability of a particular individual person - let's call her 王芳 - doing something at the extreme right hand side of the x-axis, which is time, if we keep our mitts off the process shown in the graph and do not interfere. This could be something as simple as breathing, or a more complicated thing like eating lunch, robbing a convenience store, winning a Nobel Prize in Chemistry, etc. The y-axis is a normalised arbitrary log axis showing the possibility of 王芳 doing something that we recognise as a behaviour characteristic of fully individuated human beings at time t = 1.
Here is the graph:
Now, in our scientific understanding of what happens at conception, there is a vanishingly small probability that this particular girl, 王芳, will ever do any of the things we have postulated that she might do before a bundle of physical and chemical events that are very close together on the x-axis: after that bundle of events the probability is higher by many many orders of magnitude. This bundle of physical and chemical events is close enough to be, for all practical purposes, a discontinuity in this graph. This is the only interesting point on the graph. This is the only point where there is any philosophical justification, in the scientific (i.e., experimental-evidence-based) worldview for saying: at this point in time we don't need to apply any moral consideration to 王芳; over here, we do. That is what science says. Note that concerning ourselves with an individual is all important. If we were to pretend that people are interchangeable and of no particular value as individuals, and drew a graph showing the probability of some theoretical person, rather than 王芳 specifically, we would not get a sharp discontinuity in the probability function.
Obviously, this discontinuity is a pre-implantation point.  This might not be a convenient point, or a practical point, but it is the only logical point to draw a moral distinction. In a scientific worldview.
So we can overlay a 'should we care?' function on 王芳's graph:
The only philosophically tenable way to pick some other point on this graph is to postulate some non-probabilistic, non-scientific, definition of what it means to be human. Let's say that people are only people if they have 'souls'. People without 'souls' are just meat puppets. How do you know if they have 'souls' or not? They aren't things that you can detect scientifically. You can hope for a divine revelation. Or you can muddle it out as best you can.
Here is the answer given by Statius to Dante in Purgatory, explaining how it works:
The perfect blood, which never is drunk up
Into the thirsty veins, and which remaineth
Like food that from the table thou removest,
Takes in the heart for all the human members
Virtue informative, as being that
Which to be changed to them goes through the veins
Again digest, descends it where 'tis better
Silent to be than say; and then drops thence
Upon another's blood in natural vase.
There one together with the other mingles,
One to be passive meant, the other active
By reason of the perfect place it springs from;
And being conjoined, begins to operate,
Coagulating first, then vivifying
What for its matter it had made consistent.
The active virtue, being made a soul
As of a plant, (in so far different,
This on the way is, that arrived already,)
Then works so much, that now it moves and feels
Like a sea-fungus, and then undertakes
To organize the powers whose seed it is.
Now, Son, dilates and now distends itself
The virtue from the generator's heart,
Where nature is intent on all the members.
But how from animal it man becomes
Thou dost not see as yet; this is a point
Which made a wiser man than thou once err
So far, that in his doctrine separate
He made the soul from possible intellect,
For he no organ saw by this assumed.
Open thy breast unto the truth that's coming,
And know that, just as soon as in the foetus
The articulation of the brain is perfect,
The primal Motor turns to it well pleased
At so great art of nature, and inspires
A spirit new with virtue all replete,
Which what it finds there active doth attract
Into its substance, and becomes one soul,
Which lives, and feels, and on itself revolves.


This is all based on the 4th century BCE embryology of Aristotle. This is why there is ambiguity in the writings of the Christian theologians of the high middle ages about 'when life begins'. These ideas of Aristotle have also been taken over into the main schools of Shi'a and Sunni jurisprudence, which is why most of them don't have a problem with very early term abortions. Much as I hate to say it, they are probably the source of the Talmudic concept that the fertilised egg is a 'tissue of water' in the first 40 days after conception.
In a religious worldview, this pernicious hypothesis of the soul might give us the following 'should we care' function on 王芳's graph:
Historically, for other reasons, mainstream Christianity has usually drawn the line more conservatively than implied by Aristotle's embryology. But whatever line we draw based on this unverifiable concept of ensouling will be an arbitrary one. Because this silly non-scientific idea of a 'soul' is embedded deeply in our culture, we think it is a difficult question to decide 'when life begins'. And that's the only reason.
Would you believe, I tried to make this point to someone a few months back in a Tweet? No wonder @damonayoung had no idea what I was getting at.

*** 
As an illustration of the complete and perfect storm of muddle a reasonably intelligent famous Professor of Biology can get into in these matters, here is a long quotation from a famous book by Richard Dawkins, where he discusses the notorious murder of John Britton, a Florida abortionist, by Paul Hill, a religious zealot:

Richard Dawkins: There are people who, because of their religious convictions, think abortion is murder and are prepared to kill in defense of embryos, which they chose to call ‘babies’. On the other side are equally sincere supporters of abortion, who either have different religious convictions, or no religion, coupled with well-thought-out consequentionalist morals. They too see themselves as idealists, providing a medical service for patients in need., who would otherwise go to dangerously incompetent back-street quacks. Both sides see the other side as murderers or advocates of murder. Both sides, by their own lights, are equally sincere.
A spokeswoman for another abortion clinic described Paul Hill as a dangerous psychopath. But people like him don’t think of themselves as dangerous psychopaths; they think of themselves as good, moral people, guided by God. Indeed, I don’t think Paul Hill was a psychopath. Just very religious. Dangerous, yes, but not a psychopath. Dangerously religious. By the lights of his religious faith, Hill was entirely right and moral to shoot Dr Britton. What was wrong with Hill was his religious faith itself. Michael Bray, too, when I met him, didn’t strike me as a psychopath. I actually quite liked him. I thought he was an honest and sincere man, quietly spoken and thoughtful, but his mind had unfortunately been captured by poisonous religious nonsense.
Strong opponents of abortion are almost all deeply religious. The sincere supporters of abortion, whether personally religious or not, are likely to follow a non-religious, consequentionalist moral philosophy, perhaps invoking Jeremy Bentham’s question, ‘Can they suffer?’ Paul Hill and Michael Bray saw no moral difference between killing an embryo and killing a doctor except that the embryo was, to them, a blamelessly innocent ‘baby’. The consequentionalist sees all the difference in the world. An early embryo has the sentience, as well as the semblance, of a tadpole. A doctor is a grown-up conscious being with hopes, loves, aspirations, fears, a massive store of humane knowledge, the capacity for deep emotion, very probably a devastated widow and orphaned children, perhaps elderly parents who dote on him.
Paul Hill caused real, deep, lasting suffering, to beings with nervous systems capable of suffering. His doctor victim did no such thing. Early embryos that have no nervous system most certainly do not suffer, And if late-aborted embryos with nervous systems suffer- though all suffering is deplorable- it is not because they are human that they suffer. There is no general reason to suppose that human embryos at any stage suffer more than cow or sheep embryos at the same developmental stage. And there is every reason to suppose that all embryos, whether human or not, suffer far less than adult cows or sheep in a slaughterhouse, especially a religious slaughterhouse where, for religious reasons, they must be fully conscious when their throats are ceremonially cut.


You probably know the name of Professor Dawkins' book, so it is not surprising that he associates opposition to abortion only with religious worldviews. Note how totally his argument embodies the arse-about-face confusion I have been discussing: although he says opponents of abortion are 'almost' all deeply religious, he doesn't consider any possible non-religious motivation for believing that life begins at conception, and that therefore abortion and embryonic research are wrong.

I am going to go off on a tangent briefly and look at the argument Dawkins poses that Paul Hill killing John Britton was wrong, but John Britton killing embryos and foetuses is okay.
How do the ‘well-thought-out consequentionalist morals’ of Dawkins distinguish between the two cases?

(1) Suffering of the Victim.
An embryo without a developed nervous system does not suffer, while a more grown human does. Richard does not take this argument very seriously, or else he would take much more care to distinguish between an early-aborted embryo and a late-aborted foetus with a developed nervous system. Instead of citing some experimental data on foetal suffering in animals, drawing a line at say, three months of gestation, and standing firm with Jeremy Bentham, he throws in an irrelevant statement that foetal suffering is, at any rate, less than that of sheep in halal or kosher slaughterhouses. This is a complete non sequitur as far as logic goes. Emotionally, it is a different story, and I have long felt that the anti-abortion movement should logically also take a stand for innocent animals and oppose carnivory. But suddenly bringing in halal butchers has no logical connection whatever with the ‘they can’t suffer, so it’s okay to kill them’ argument. It is just there to provoke people’s self-interest: ‘Gee, Professor Dawkins is implying that if I oppose abortion, I ought to give up eating meat. But I don’t want to do that…”

Conversely, let us now consider the suffering of Dr John Britton. Is it really his suffering that is important? Let's say that instead of laying in wait for him with a shotgun, Paul Hill had waited until he was deeply asleep and then painlessly administered a lethal injection? Would the State of Florida have said, ‘Oh, that’s fine, you can go on your merry way, plucky lad?' As far as I know, Paul Hill was a pretty good shot and John Britton’s death was instantaneous and painless. On the other hand, if I were to go to Florida and try to shoot an abortionist, having never had much hand-eye coordination, I’m sure I would at worst wing them and they would come good in the end, after a whole lot of immediate pain and months or years of physio. Yet, Jeb Bush would not have connived at my judicial murder for the attempted killing of a doctor. 

The question ‘can they suffer?’ is the wrong question. It is irrelevant to proper ‘well-thought-out consequentionalist morals’, since you can murder someone without them suffering at all and we all agree this is bad.

(2) Suffering of the Victim’s Friends.
Richard points out that John Britton had: ‘…a devastated widow and orphaned children, perhaps elderly parents who dote on him.’ All of these people will obviously feel real suffering at his loss. But if this is the consequentionalist reason not to kill him, then what about people who have no friends? Is it more permissible to knock them off? I have seen this argument seriously advanced with respect to animals (e. g., C. S. Lewis, The Problem of Pain) but so far as I know, only facetiously with respect to humans (e. g., Jonathan Swift, A Modest Proposal). 

Does the argument that it was wrong to kill John Britton because people were sad about his death imply that if I were to distribute lurid details of his activities beforehand to millions of members of my militant anti-abortion group,* so that his continued existence caused them suffering and they were really happy about his death, then it would be okay? I think the answer would have to still be, no.

(3) Loss of Potential.
Richard points out that John Britton had ‘…hopes, loves, aspirations, etc.’ What does this mean? It means that if he had not been killed, chances are he would be enjoying his retirement now. He might be out playing golf. He might be writing entertaining novels, like the retired Colorado Planned Parenthood bigshot Sheri S. Tepper. He could be travelling around in a campervan, or sitting in front of the TV doing Sudoku. These are all things he could have been doing that have been brutally and unfairly taken away from him . Chances are, he would have been doing something that pleased him and enriched the universe in some way. He is not; his life has been cut short with his potential unfulfilled, and that was why it was wrong to kill him.

That is also why it was wrong for him to kill those embryos and foetuses.

For, if those embryos John Britton killed had not been killed, they too might now be playing golf or sitting in front of the TV. There is very nearly as good a probability that they would have gone on to do these things as there was that John Britton would go on to do them. The only difference is the difference between the seen and the unseen: we saw a great deal of John Britton’s potential unfold; we did not see the potential of those embryos and foetuses unfold, because their lives were brutally and unfairly taken away from them. The consequence of the killing of those human individuals is that they were denied the whole of the life that we other human individuals take for granted, and if ‘consequentionalist morals’ do not consider that as a valid consequence, I think they need another name.

Note that this tangential discussion has not mentioned God. It has not mentioned religion. It has not assumed the existence of an absolute morality. It is based purely on what we all, intuitively, understand to be so bad about premature death. To my mind, it is a 'well-thought-out consequentionalist morality' eminently suitable for theist and atheist alike.


***

To dispose of one more possible objection, the idea of 'being able to live independently' is sometimes raised as a logical place to draw a line netween people we should care about and people we shouldn't. This is not tenable, because no human being can live independently. We are social animals who need the support of others of our kind to became capable of independent life. So, a foetus cut out of its mother cannot breathe, and dies. A newborn infant left in a room next to a fridge full of formulae cannot feed itself, and dies. An urban man dropped naked in the wilderness is clueless, and dies. There is no discontinuity in this curve where we can draw a line.


***

Finally, you are free to think that I am only playing logic games to reach a pre-determined conclusion. I can't testify objectively as to whether that is true or not. I did try to be a Catholic for a very long time, and how I think and feel is shaped by my life experience. I can only say that, subjectively, my life has seemed from the inside to be a process of figuring things out, of trying to approach truth in a logical and self-consistent way, of painfully letting go of things I had felt I ought to believe that didn't fit into this process, and of reluctantly believing things I couldn't disbelieve any more as this process went on. That's what it looks from here.




*: I am not really the mastermind of a militant anti-abortion group with millions of members. This is a hypothetical. Please don't tap my phone.