Massachusetts Institute of Technology, Cambridge, Massachusetts

A quantum mechanic considers how we might ‘talk’ to aliens

So it finally happens. After hundreds of years of humans attempting to communicate with extraterrestrial beings, our descendants receive a message back. But it looks like utter gibberish. What to do? Earthlings might, for example, find some middle ground by sending the aliens a stream of circularly polarized photons to explain what we mean by left handedness. Or maybe the aliens would be able to decipher simple mathematical formulae, encoded in a binary alphabet, through which we could gradually build up a mutual understanding of mathematics, logic, and so forth?

That might work, but what if the replies are still nonsensical? Brendan Juba and Madhu Sudan recently supplied a mathematically precise answer to this question (B. Juba and M. Sudan Symp. Theor. Comput. 123–132; May 2008). Using the theory of interactive proofs, which shows how parties who possess different pieces of a theorem’s proof can cooperate to construct a full proof, they show that as long as aliens are not completely indifferent to communications from Earth, we will quite quickly be able to ascertain whether or not they have knowledge that is useful to us.

The technique that Earthlings should use goes like this: Bob, the human, systematically encodes questions about a class of problems in a form that any computer can interpret. He then repeatedly sends the encoded questions to Alice, the alien, and carefully parses the apparent gobbledygook that she sends back. Juba and Sudan prove that if Alice knows the answers to Bob’s questions (that is, were the questions asked in her own language), and actually answers some non-neglible fraction of those questions (again, in her own language), Bob can determine what she means.

So communicating with aliens is possible in principle, no matter how unpromising the task may seem. I find that reassuring.

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Queen's University, Belfast, Northern Ireland

A microbiologist learns that all marine creatures must suffer for the greed of a few.

Phosphate is an essential nutrient for all forms of life. Demand for it tends to outstrip supply to such an extent that it limits the overall productivity of many ecosystems, including vast tracts of the seas. I study the curious strategies by which creatures obtain sufficient phosphate for life as they know it.

Some microorganisms, for instance, keep a phosphate store for when times are hard. They scavenge for the nutrient in their surroundings with high-affinity uptake systems and then produce polyphosphate, an insoluble polymer that packs hundreds of phosphate subunits into a single strand. Strands of polyphosphate then form intracellular granules that can be broken down by cellular enzymes when they are needed.

This kind of 'luxury' uptake was recently the focus of a study by Ellery Ingall of the Georgia Institute of Technology in Atlanta and his colleagues. Diatoms — unicellular, silica-walled algae — accumulate phosphate during summer blooms to levels far beyond their immediate needs. Indeed, polyphosphate produced by plankton accounted for 7–11% of the total phosphate in the surface waters of Effingham Inlet, a fjord on Vancouver Island, Canada (J. Diaz et al. Science 320, 652–655; 2008).

This self-indulgent behaviour seems to have far-reaching consequences. Decaying plankton eventually sink to the ocean floor, where they spill unused polyphosphate onto the sediment surface. Notably, Ingall and his team found that soluble phosphate was not released at this point. Instead, polyphosphate molecules seeded the precipitation of minerals called apatites, a process that took only a few years. So diatom greed may ultimately lower the ceiling on marine productivity by locking away the oceans' most hard-to-come-by nutrient. That is important as well as curious.

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University of Sheffield

A palaeobiologist calls for greater biological realism in climate models.

The world's most sophisticated climate models fail to adequately replicate climate at high latitudes and over continents' interiors during ancient periods of greenhouse-gas-induced warming: the wintertime predictions are consistently too cold. This makes me worry that the field is missing fundamental feedback processes that amplify warming. If so, climate models might be underestimating how much anthropogenic warming will happen in the future.

What might these mysterious processes be? Lee Kump and David Pollard of Pennsylvania State University in University Park think they have found one. They propose that marine phytoplankton that emit dimethylsulphide — already recognized as a major source of cloud-seeding particles far out to sea — became thermally stressed during the Cretaceous period (100 million years ago). As a result, the phytoplankton grew more slowly and reduced their emissions. Fewer biologically derived aerosol particles meant fewer nuclei for cloud condensation, which, in turn, led to less extensive cloud cover and more transparent clouds. Solar radiation was thus reflected less, and polar temperatures rose by 10–15 °C (L. R. Kump and D. Pollard, Science 320, 195; 2008).

Kump and Pollard's work is exciting for its dramatic result. Nevertheless, the duo's findings are ultimately unsatisfactory; the effects of heat on biological aerosol emissions need to be better described in their model for it to generate really solid conclusions. Although some recent field and laboratory experiments do suggest that marine algae produce less dimethylsulphide when carbon dioxide concentrations approach those of the Cretaceous, much more research is needed. If such results agree with Kump and Pollard's assumptions, I might worry less about climate models — but maybe even more about global warming.

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University of California, Los Angeles

An epidemiologist points to a fifth sort of human malaria.

Malaria has plagued humans since the dawn of written history, and probably since long before that. These days, biologists understand tiny mechanistic details of the workings of one human malarial parasite, Plasmodium falciparum, but know surprisingly little about the others. As someone who studies how pandemics are born and die — and how they might one day be prevented — these holes in our knowledge seem striking to me.

Aside from P. falciparum — the cause of 'malignant' malaria — parasitologists acknowledge three other human malaria parasites, P. vivax, P. ovale and P. malariae, each of which probably jumped from another primate host to humans independently. With so many malaria parasites plaguing other vertebrate species, however, and only basic diagnostic instruments available in most parts of the world, science could be missing new types of human malaria that have the potential to seed pandemics.

In a recent paper, Janet Cox-Singh and her colleagues build on their earlier finding that humans can harbour a fifth malaria parasite, P. knowlesi, which was once thought to infect only Asian monkeys. The researchers detected P. knowlesi DNA in about one third of 1,014 malaria patients in Malaysia, showing that this parasite is common, deadly and almost always misidentified as P. malariae (J. Cox-Singh et al. Clin. Infect. Dis. 46, 165–171; 2008).

That an unknown animal pathogen can cause widespread human disease is reminiscent of some of the biggest scourges of the twentieth century: HIV and pandemic influenza. Reductionist, molecular approaches to tackling important plagues may be en vogue and a near necessity for grant funding, but I bet that an old-fashioned natural historian studying how infectious agents jump host species will be first to signal the coming of the next plague.

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