Thursday, 27 August 2009

Blogosphere fame

How exciting - our pipes paper has been picked up by the online technology blog/journal Ars Technica under the (admittedly obvious) banner of "Latest carbon sequestration idea could be another pipe dream". And they've done a good job of it as well, possibly on account of not having spoken to me about it. Anyway, needless to say, I'm really chuffed.

Sunday, 23 August 2009

Outlaws in Hamble

Had a nice day out in Hamble (or "Hamble-le-Rice", as it's known on Wikipedia) with the outlaws today. Really just a short walk into the town's waterfront, then across the river on the Pink Ferry for a slightly longer walk up the eastern riverbank. A beautiful blue sky, heavily criss-crossed, for some reason, with planes today. Somehow I never tire of the latter, as evidenced in the walk's photographs.


Friday, 21 August 2009

Pipes published

Finally, after two inexplicably long review-revision-resubmission cycles, our paper on the efficacy (or not) of ocean pipes is finally formally published. I say "inexplicably" because neither review cycle turned up much in the way of major problems with the paper. Reading between the lines, I suspect that difficulties getting reviewers, and getting them to submit reviews on time, has been the main source for our frustrations.

Anyway, what does the paper say? Essentially it explores what the consequences would be if you "plumbed-in" the whole of the ocean (well, wherever it's > 1000 m in depth) with pipes that transfer seawater from its interior to the surface (cf. the figure to the left). The idea behind such pipes is that they would channel high concentrations of deep nutrients to surface waters, where they can fuel the growth of phytoplankton, increase the uptake of CO2, and thus potentially decrease climate change.

In our work we did quite short simulations of the recent past (1995-2004) in which we explored what happened to primary production, export production and the air-sea flux of CO2 when pipes of three lengths (200, 500 and 1000 m) were switched on, relative to a control simulation for the same period.

What we found was that the pipes did the business in terms of primary and export production, with significant increases in both (although we did assume that the pipes were moving a comparable amount of water to that naturally translocated by ocean circulation). However, we also found that, by contrast, the air-sea flux of CO2 was only marginally increased by the pipes. In part, this was because we just ran the pipes everywhere without any consideration as to whether they would bring up more DIC than they'd be able to sequester, and the consequences of this can be seen in the figure below. The big blue areas in the lower row are places where, because of the deep carbon:nutrient ratios, the pipes channel more CO2 to the surface than can be drawn down by the transported nutrients.

However, even factoring out areas where the ocean was turned from a sink of CO2 into a source, we found that for every 100 moles of extra carbon fixed by phytoplankton, there'd be only 2-3 moles extra drawn from the atmosphere. And then, by doing a big back-of-the-envelope calculation, we estimated, based on our results, that to increase the ocean's uptake of CO2 by 50%, we'd need to deploy around 800 million pipes in the oligotrophic tropical ocean. Of course, there are a lot of caveats in our paper that cover what's wrong with our model, our simulation and our assumptions, but we tend to think that our sums are about right to first order (but then we would!).

In the paper, we completely avoided tackling what the "side effects" of the pipes could be (although one of my co-authors finds some really interesting ones in a separate study), just so we could focus on the basic: "do the pipes work?". Taking a somewhat ethical stance, one thing that they would do would be to replace the oligotrophic "desert" communities of the subtropical gyres into the more mesotrophic communities typical of upwelling areas. As a biologist, I don't like the idea of decreasing biodiversity just so that we can avoid the unwanted consequences of our actions, but at the same time I think it's good to know how efficient this sort of geoengineering scheme is just in case we do need a drastic solution to climate change down the line. Though hopefully we'll see sense before then ...

Monday, 17 August 2009

Hard, Harder, Hardest

After a short break from science fiction, I've returned with a vengeance: the ultra-hard, hard science fiction of Schild's Ladder by the Australian author Greg Egan.

Schild's Ladder is set in the distant future, where the giants of 20th century physics are now quaintly described as "the ancients". Their intellectual offspring, general relativity and quantum mechanics, have long [*] been combined into a unified framework, the Sarumpaet rules, named after the long-dead physicist most associated with them. Much as with other Egan novels, humanity has spread among the stars and exists in a number of physical forms at this point. Natural humans, others who live in synthetic organic or mechanical bodies, and those who have forsaken embodied life and exist in computing infrastructure as so-called Qusps. The novel begins with the arrival of Cass at the Mimosa facility 600 light years from Earth. Cass is a physicist interested in quantum graph theory and with new ideas about how the Sarumpaet rules can be tested much more strenuously than ever before. The Mimosa facility affords a quantum mechanical "quietness" that can best allow these tests, and after pleading her case with its administrators, Cass is permitted to begin her experiments. However, despite all of the precautions that Cass and the Mimosans take, the final test goes "wrong" and a startling transformation of the universe's underlying spacetime occurs, creating a fast-expanding "novo-vacuum" with radically different physical properties. Her consciousness copied to a Qusp to watch the experiment at ultra-high speed, Cass and her colleagues watch, horrified, as this novo-vacuum expands to destroy the Mimosa facility.

The novel then jumps forward several hundred years. The novo-vacuum has continued to expand at half the speed of light and by now has consumed a number of inhabited systems. While casualties have been extremely light because of the predictability of the expansion, a Preservationist faction has arisen to contain or even destroy the novo-vacuum. But a Yielder faction balances them, composed of those who believe that adaptation to the novo-vacuum may be possible and that this new state of affairs has shaken up a torpid and stale society. Tchicaya is one of the Yielders who has joined a joint mission with the Prevervationists that has positioned a ship, the Rindler, just beyond the moving envelope of the novo-vacuum. From there the mission observes and performs experiments on the blossoming physical realm expanding just behind their ship. Tchicaya is unsettled by the arrival of his first, but unconsummated, love, Mariama, now one of the Preservationists. He is haunted by the event that divided them centuries before, their discovery of primitive, native life on a colonised world, a finding that led to the quarantine and evacuation of the planet. Humanity has found life to be exceedingly rare, and none of what has been found has approached sentience, so for Tchicaya the novo-vacuum offers the possibility of a new realm to search for it. However, even the nature of the "space" that lies behind the novo-vacuum's border is uncertain, prolonging the incomprehension of the human factions, and allowing the divisions between them to grow.

But a breakthrough in understanding opens the door both to exploration of the novo-vacuum and to the invention of weapons, the planck worms, that may assist in its destruction. Further exploration reveals a physics in the "far side" much richer than that in the "near side", one in which the ostensible vacuum itself writhes with apparent life. What's more, deeper probes into the far side discern unexpected structure and trigger apparent signals from organisms living there, dubbed the vendeks because of their size. At the same time, a sub-faction of Preservationists makes a desperate bid to wrest control of the Rindler, and initiates the release of the planck worms. Faced with the potential loss of the first sentient life that humanity has long been searching for, Tchicaya and Mariama abandon corporeal form and transmit themselves to the far side.

As the (over)long outline above implies, this is a novel with a well thought-out plot, and one which I generally really enjoyed. But it comes with a huge caveat. As I noted right at the start, this is hard science fiction with a capital HARD, and while Egan has created an exciting and imaginative future, he's also carefully thought through the physics that underlies the story. And, unfortunately (for this reader at least), not just thought about it, he's actually jammed it wholesale into the book.

Now, Egan hasn't gone so far to include any equations (though he does include one or two diagrams), but his language is extremely physics-heavy, and long sections of the prose delve, unremittingly, into the extrapolated physics that he's invented for the novel. He's good enough a writer for it to avoid being clunky, in fact it sounds convincingly like mathematical conversations I've eavesdropped over the years, but it's still the sort of thing that's only ever going to be understood fully by that small minority of readers with a strong interest in theoretical physics. I understood practically none of Egan's description, and had to take almost all of it with a pinch of salt, much as I occasionally do at work when some aspect of physical oceanography is being explained.

The upshot of all this is that the novel is something of a compromised read. On the one hand, it's hardly satisfying to have to essentially skim read long sections of the novel (especially given the effort that's clearly gone into them), but on the other hand, Egan has created a very imaginative and enjoyable (when away from the physics) far-future romp. I particularly took to the theme of looking for alien life, the significance this had to Egan's characters, and the lengths to which they'd go to protect it. I also really liked the idea that our world, far from being the pinnacle of creation, is actually an impoverished backwater, a near-lifeless ocean of empty space, while the novo-vacuum (sic) is teeming over with life. But then, I'm always a sucker for anthropic pedestal-knocking.

Anyhow, leaving aside the physics, the novel works pretty successfully. The plot rolls steadily along, with a lot of nice detail blended in, and with a nice progression to the climactic exploration of the far side. As with much science fiction, the characters definitely take something of a backseat, at times to the point where I struggled to work out which of the secondary characters was speaking, and for what faction. But by having only a few main characters, even ones who were not quite fully three-dimensional, I never drifted too far. But it would still be a little difficult to recommend to anyone other than a fan of the hard. Egan's zeal to show the workings behind his fictional world is admirable in a way, but here it really interferes with his storytelling. Other authors like Iain M. Banks occasionally introduce transcendent physics (or the appearance of it), but they do so more through lyrical or qualitative prose than the laying out of carefully-crafted mathematical edifices (which, in the case of Banks at least, is in no small part down to him having a BA rather than a BSc).

In passing, this trait of comprehensively nailing the physics is not a new one for Egan. The novels of his that I read pre-blog, Permutation City and Diaspora, also lay the physics on rather thickly. The former deals with the transfer of minds to something like the Qusps here, and also, curiously enough, with the evolution of alien life created by human actions. Meanwhile, the latter significantly broadens its scope, beginning with the development of a Qusp from its (or vis, to use the novel's pronouns) virtual birth, and ending with a search for extraterrestrial intelligence that ultimately jumps from universe to universe through a vividly created multiverse. Interestingly, Egan's short fiction, by virtue of its length, generally steers him away from long expositions of physics, so plays to his strengths as a master of ideas.

[*] Though the novel is set around 20,000 years in the future, Egan kindly drops the unification of GR and QM back at the "turn of the third millennium". Which, given the enormous (but still small) jump forwards in time, probably comes as some relief to theoretical physicists. He could have dropped it at the "turn of the fifteenth millennium", which would have still been ancient history for most of the novel's characters, but that would have made for a rather withering assessment of progress in contemporary physics.

Thursday, 13 August 2009

Parents + Portsmouth + Photography

Took a trip to Portsmouth Harbour to look around the seafront and Gunwharf. We were put off by the large queue for Spinnaker Tower so the photographs I took were strictly ground level.


Wednesday, 12 August 2009

Failed Briton

It's been confirmed at last: I'm a failure as a British citizen. I took the test but barely managed to scrape half-marks, which surely comfortably tags me up for imminent deportation ...

You have failed the practice citizenship test.

Questions answered correctly: 12 out of 24 (50%)

Time taken: 04 minutes 22 seconds

I can't be sure why I failed (the site doesn't help you there), but some of the questions were pretty strange. For instance, there were a number that could only be answered by demographers familiar with census data, and a couple of others that asked the test subject to select the correct of several similar-sounding organisations. But the overwhelming problem, as far as I could see, was that they tested knowledge of irrelevant or arcane British factoids.

I seriously doubt that, despite being a UK citizen, I'm unusual in failing the test. It's the sort of thing that's sufficiently poorly-judged that one begins to question the wider credibility of government activities.

Bird life

No change in the quad. We've still got the same 9 chicks (7; 2), and we've still got our seagull on the roof opposite. The latter is spending most of its time away, but still pops back every now and again.

I'm now waiting for the ducks, at least the first batch, to try flying out of the quad. At the moment they seem to be doing very little down there, possibly because their mother is long gone. In continuing a pattern of neglect that would have the authorities round for a human, duck mothers don't even appear interested in making sure their offspring take to the wing. Not so with the seagulls, who periodically, but gently, "bullied" their chick into the air.