Minimizing the cost of producing a desired power density at long range … determines the maximum range of detectability of a transmitted signal. We derive general relations for cost-optimal aperture and power. … Galactic-scale beacons can be built for a few billion dollars with our present technology. Such beacons have narrow “searchlight” beams and short “dwell times” when the beacon would be seen by an alien observer in their sky. … Cost scales only linearly with range R, not as R². … They will likely transmit at higher microwave frequencies, 10 GHz. The natural corridor to broadcast is along the galactic radius or along the local spiral galactic arm we are in. …

Cost, spectral lines near 1 GHz, and interstellar scintillation favor radiating frequencies substantially above the classic “water hole.” Therefore, the transmission strategy for a distant, cost-conscious beacon would be a rapid scan of the galactic plane with the intent to cover the angular space. Such pulses would be infrequent events for the receiver. Such beacons built by distant, advanced, wealthy societies would have very different characteristics from what SETI researchers seek. … We will need to wait for recurring events that may arrive in intermittent bursts. …

A concept of frugality, economy. … directly contradicts the Altruistic Alien Argument that the beacon builders will be vastly wealthy and make everything easy for us. An omnidirectional beacon, radiating at the entire galactic plane, for example, would have to be enormously powerful and expensive, and so not be parsimonious. … For transmitting time t, receiver detectability scales as t^1/2. But at constant power, transmitter cost increases as t, so short pulses are economically smart (cheaper) for the transmitting society. A 1-second pulse sent every 10 minutes to 600 targets would be 1/600 as expensive per target, yet only *1/25 times harder to detect. Interstellar scintillation limits the pulse time to >10^-6 s, which is within the range of all existing high-power microwave devices. Such pings would have small information content, which would attract attention to weaker, high-content messages. …

Cost-optimized beacons … can be found by steady searches that watch the galactic plane for times on the scale of years. Of course, SETI literature abounds with consideration of the trade-offs of search strategy (range vs. EIRP vs. pulse vs. continuous (continuous wave, CW) vs. polarization vs. frequency vs. beamwidth vs. integration time vs. modulation types vs. targeted vs. all-sky vs. Milky Way). But, in practice, search dwell times are a few seconds in surveys and 100–200 seconds for targeted searches. Optical searches usually run to minutes. And integration times are long, of order 100 s, so short pulses will be integrated out. …

Behind conventional SETI methods lies the assumption that altruistic beaming societies will send persistent signals. In searches to date, confirmation attempts, when the observer looks back at a target, in practice usually occur days later. Such surveys have little chance of seeing cost-optimized beacons. … Distant, cost-optimized beacons will appear for much less time than as assumed in conventional SETI. Earlier searches have seen pulsed intermittent signals resembling what we (in this paper) think beacons may be like, and may provide useful clues. We should observe the spots in the sky seen in previous work for hints of such activity but over year-long periods. (more)

Of course both the usual assumption that aliens will pay any cost to make a given power density signal easy for us to see, and the new assumption that aliens ignore our costs and merely seek to maximize power density, are both somewhat unsatisfactory. It would be better to model this interaction as a game, where each side has a limited budget and seeks to maximize the probability of at least one successful communication, holding constant the behavior it expects from the other side. Each side would of course also have to integrate over possible locations and budgets for the other side.

I’m very interested in working with (sim, math, or physics) competent folks to more formally model this SETI communication game.

It would be very difficult to produce a model that convincingly predicts the likelihoods and spatial distributions of the various strategies, since the answer surely depends on many unknowns.

He instead just claims:

The hypothesis is certainly not logically inconsistent and it seems to me not entirely implausible.

So what then is Kent’s contribution? Apparently it is a bunch of strategy fragments, i.e., strategy issues that aliens might consider in various related situations. It is not clear that these are much of a contribution, at least relative to the many contained in related science fiction novels. But, well, here they are:

Even granted an exemplarily stealthy attack and takeover, the mere fact that the previously conspicuous species B is no longer so gives a clue to observers elsewhere that some other species A, with its own potentially interesting resources, may now be in occupation — and hence that it may also perhaps be worth exploring the neighbourhood for other habitats that species A occupies. …

A really cautious predator might perhaps try to take over species B’s habitat while giving the impression that species B had self-destructed. This might or might not be believed: however good the cover story, it would presumably lose credibility if a number of independent species on different habitats in a given region appeared to self-destruct within a statistically implausibly short time interval. If B’s takeover is detected or inferred by species C, they might be tempted to jump in. But so might species D, E, and so on. …

Species may be induced to predate on conspicuous near neighbours even if their general strategy is to remain inconspicuous and avoid predation. Noisy neighbours are liable to attract unwelcome attention to the neighbourhood. One could perhaps run as far away as possible, but this requires finding another unoccupied and inconspicuous habitat. … There is the added danger that one risks becoming conspicuous to predators during the search. …

Assuming there is currently no dominant predator, any predators which attempted dominance in the past must have come to grief. (Perhaps this seems unlikely: if it was defeated by another predator, why would that predator not have come to dominate? And is it really plausible that a very powerful but reticent stay-at-home could, when threatened, have taken out a predator with galactic ambitions?

Kent seems to neglect the value of constructing any remotely plausible self-consistent equilibrium. We might gain great insight from such models, even if they are far from accurate on “likelihoods and spatial distributions of the various strategies.” Kent also seems to overestimate the resource value of inhabited places, relative to uninhabited places. His key assumption:

One imagines that an inhabited planet, together with the ecosystem it supports, constitutes a resource that would be valuable to (some significant subset of the) species originating on other planets.

Inhabited places might be a bit more valuable, but mainly they’d be of interest as potential competitors for all the other resources around.

I’d be interested in working with (math or sim) competent folks to more formally model berserker scenarios.

Planetary anthropic selection, the idea that Earth has unusual properties since, otherwise, we would not be here to observe it, is a controversial idea. This paper … [compares] Earth to synthetic populations of Earth-like planets … [for] high (or low) rates of Milankovitch-driven climate change. Three separate tests are investigated: (1) Earth-Moon properties and their effect on obliquity; (2) Individual planet locations and their effect on eccentricity variation; (3) The overall structure of the Solar System and its effect on eccentricity variation. In all three cases, the actual Earth/Solar System has unusually low Milankovitch frequencies compared to similar alternative systems. All three results are statistically significant at the 5% or better level, and the probability of all three occurring by chance is less than 10^-5. It therefore appears that there has been anthropic selection for slow Milankovitch cycles. This implies possible selection for a stable climate, which, if true, undermines the Gaia hypothesis and also suggests that planets with Earth-like levels of biodiversity are likely to be very rare.

Regions of Earth that have stable temperatures (e.g., tropical rainforests) have high levels of biodiversity. The hypothesis that this link is direct and causal is reinforced by the observation that the deep ocean seafloor also has high biodiversity, even though the conditions are, stability excepted, poor and biological productivity therefore low. Further evidence of a link between rapid climate change and loss of species richness has been gleaned from studies of Earth’sglacial-interglacial cycles. The most recent ice ages have resulted in reduced biodiversity within the temperate zones where the greatest changes in climate occurred. There are, therefore, two independent lines of evidence that support the proposition that biodiversity is, in general, lower when climate change is significant. …

I concentrate on the climatic influence of Milankovitch cycles, that is, the periodic variations in Earth’s climate that are induced by changes in Earth’s orbit and orientation in space. The key factors here are axial precession (time varying axis orientation), orbital precession (time varying orbital orientation), and time variation in orbital eccentricity (circularity of the orbit). Note that changes in obliquity (the tilt of Earth’s axis relative to its orbit) are the consequence of interaction between axial precession and orbital precession, and this important factor is therefore included in the following analyses. The evidence that Milankovitch cycles affect Earth’s climate is secure. (more)

When adjacent space-time places have different local physics, there must be a common “meta” physics that describes their border. This meta-physics will say how often places of one type lead to places of other types nearby, including “ends” where nothing is nearby.

Let us distinguish two special kinds of places:

• Gardens support life and possibly civilization.
• Fertile places tend to lead to more fertile places nearby.

The existence of any fertile place implies an expected infinity of connected fertile places. Thus when meta-physics maintains a one-to-one state map across a time dimension, there should be no finite upper bound to the entropy of a fertile place. Thus the entropy at a fertile place is always vastly lower than is possible, and entropy would increase in some local time direction. Since this low entropy should infect adjacent places, non-fertile places “close enough” to fertile ones should also have entropy increasing away from the fertile side. Thus we can explain our local “arrow of time” by assuming that our place is connected to a fertile place in our distant past.

Is our garden fertile? If both gardens and fertile places are rare, and these properties are not very correlated, then fertile gardens would be especially rare – it would be quite unlikely that our garden is fertile. In this case, while our universe is infinite, our future is finite, and will see and influence only a finite amount before our space and entropy run out.

Cosmologists today, however, tend to think that fertile places are not very rare. They expect places with a “positive vacuum energy” and a “low vacuum decay rate” to generate many “baby universes”, and that many of these baby universes also satisfy this description. In fact, they guess that our place here satisfies this description, and so is fertile. (This is, basically, Sean Carroll’s account of our arrow of time.)

But a whole lot of guess work goes into all this. For example, it could be that vacuum decay rates are much higher, and that baby-universe-generating rates are much lower, than they’ve guessed. My guess is that this property of being fertile is rarer than cosmologists now guess, which lowers the chance of our garden being fertile.

A correlation between being a garden and being fertile might result if civilizations tended to work to increase the rate at which their places lead to more places nearby. But it might be that for most gardens there isn’s much civilizations can do.  In which case if fertile places are rare, then most gardens are not fertile, our future is finite.

Finally, even if our place is fertile, it might be that the border between our place and other different places has no “hair” letting us send specific influences from here to there. In this case, our future influence would still be finite.

A new Journal of Cosmology article says that sealed deep in the water-clay-full sort of (CI1 carbonaceous) meteorites that likely come from comets, one consistently finds forms that look visually and chemically like ancient bacteria fossils. Typical reactions:

This effort clearly falls into the category of “extraordinary claims” that require extraordinary evidence. (more)

Dr David Marais, an astrobiologist with NASA’s AMES Research Centre, said he was very cautious about jumping on the bandwagon. These kinds of claims have been made before, he noted and found to be false. “It’s an extraordinary claim, and thus I’ll need extraordinary evidence,” he said. (more)

Those are odd and intriguing formations, to be sure. … Contamination, no matter how unlikely, is a more mundane explanation than extraterrestrial life, and Occam’s Razor will always shave very closely here. We have to be very, very clear that contamination was impossible before seriously entertaining the idea that these structures are space-borne life. I’ll be honest: my own reaction is one of extreme skepticism. As it should be! All things being equal, I would take news like this with a very large grain of salt, and want a whole lot of outside expert analysis. (more)

The last one links to this explanation:

Extraordinary claims require extraordinary evidence because they usually contradict claims that are backed by extraordinary evidence. The evidence for the extraordinary claim must support the new claim as well as explain why the old claims that are now being abandoned, previously appeared to be correct.

Alas, these attitudes make far more sense in status terms than in information terms.

In status terms, it would of course be big news to hear that academia had declared its consensus that alien life had most likely been found. Academia’s public and patrons would take heed, and the academics associated with inducing that event would gain high status. So academics want to ensure that only folks with quite impressive academic abilities could gain such a prestigious honor. Thus they naturally want to that this honor goes to folks with extremely impressive data, methods, etc. And this paper, published in a low prestige journal by a low prestige academic, using solid but not especially difficult techniques, seems below that bar.

But in information terms, this new result does seem in the ballpark of tipping us over the threshold of thinking it likely than alien life has been found.

First, our prior estimate that alien life would be found in comet-based meteorites should have been pretty high. The idea that life came here from out there is a standard reasonable view:

Panspermia is no longer a marginalized view. It may not yet be the majority opinion, but it shows up often in journal articles and conference proceedings.

Counting by volume, comets seem the most likely place to find such life, and so meteorites from comets would be the most likely place to find alien fossils. We also seem to see alien fossils from Mars. Furthermore, the only known betting market on this topic has for 15 years consistently said we’d find evidence of alien life by 2050:

Not only should our prior on finding alien life in comets be high, the likelihood of this new data seems much higher if alien comet life were common than if it didn’t exist. This new data was was careful to examine only opened surfaces in a sterile vacuum:

The study was confined to investigations of uncoated, freshly fractured, interior surfaces of the meteorites. All tools, sample holders and stubs were flame sterilized. Lunar dust samples and silicon wafers were used as negative controls. … The meteorites were stored in sealed vials at -80 oC and after preparation, electron microscopy stubs were kept in sealed containers in dessicator cabinets or in the freezer. The fusion crust and old cracks in the stones were carefully avoided. The meteorite samples were placed in the instrument chamber (with the fresh fracture surface up) a pumped down immediately after the stones were fractured. All solvents, acids or other liquids were strictly avoided. … Only one seriously Murchison sample was found to be contaminated with fungal filaments (in old cracks in the fusion crust) and not a single pollen grain has been encountered during extensive studies of carbonaceous meteorites carried out since 1996 at the NASA/Marshall Space Flight Center.

Furthermore, the chemical signatures found match ancient fossils far better than recent life. And how could meteorites that fell to Earth a century ago get contaminated with ancient Earth fossils?  Yes these forms might have non-biological explanations, but the point is the likelihood ratio – that such forms that look much like known life are much more likely given life than given not.

Informationally, a nearly neutral prior together with a strong new likelihood ratio should have us now accepting the claim as more likely than not. But academia will not publicly admit that fact until they can find a status holder to credit who they consider worthy of the honor. The journal says:

Members of the Scientific community were invited to analyze the results and to write critical commentaries or to speculate about the implications. These commentaries will be published on March 7 through March 10, 2011.

I’d bet these commentaries will mostly say this is interesting but doubts remain, that this evidence is too ordinary to support its “extraordinary” conclusion, and yet they’ll refuse to bet on the subject. How sad is that?

Added 2:30p: This claims Ladbrokes offers 1000 to one odds against finding alien life, but I can’t find more details online. This says William Hill offers 100 to one odds against “proof of the existence of intelligent extra-terrestrial life will be provided within a year”, but there’s no word on longer time scales.  PaddyPower‘s odds estimate a <20% chance “The sitting President of the USA making a statement confirming without doubt the existence of alternative life beings from another planet” after 2020, and a <30% chance for before 2020 (including a 2.5% chance for 2011).  An Intrade offer of 5% for a NASA announcement by 2013 also implies ~2.5%/year.

So argues Simon Conway Morris, from inside view considerations. I think he’s mostly right, but based on an outside view.

Here it is: when relevant parameters can vary by large magnitudes, the most common type of thing is often overwhemingly more common. For example, processes that create and transmute elements vary greatly in their rates. So even though there are over a hundred elements in the periodic table, over 90% of all atoms are hydrogen, so the odds that two randomly selected atoms are the same element is >80%.

Similarly, since the influences on how many eyes a human has vary greatly across eye numbers, most humans have the same number of eyes: two. Most humans do not have the same last name, however, since rates of gaining or changing names do not vary by huge factors.

The same principle applies to life. Life might have evolved in a great many kinds of environments, based on a great many sorts of elements, and using many types of organization. To the extent that some environments are far more common, or are far more supportive of high rates of biological activity, most biological activity in the universe should occur in the few most common and supportive environments. Similarly if some elements or organizations are far more supportive of biological activity and innovation, most life should use those elements and organization.

I expect cosmic environments to vary enormously in both volume and in support for biological activity. I also expect some types of elements and organizations to be far more supportive of biological activity and innovation. I thus expect most life to be based on similar elements and organizations, to originate and be active and innovative in places similar to where our life orginated and is most active and innovative.

This view is supported by the fact that the assumption that life originates via the entropy of sunlight hitting “dust” predicts many cosmological parameters. In ’08 I reported:

This causal entropic principle so far successfully predicts dark energy strength, matter fluctuation ratio, baryonic to dark matter ratio, and baryonic to photon matter ratio! … A simple reading of the principle is that since observers need entropy gains to function physically, we can estimate the probability that any small spacetime volume contains an observer to be proportional to the entropy gain in that volume. … Exclud[ing] entropy of cosmic and black holes horizons, … ignor[ing] future observers getting far more efficient and aggressive in using entropy, … they estimate that, aside from decaying dark matter, near us most entropy is made by starlight hitting dust, and most of that is in the past.

Our life probably started from sunlight hitting “dust” (including planets). More quotes from Simon Conway Morris:

Will the extra-terrestrials be utterly familiar, completely alien (whatever that is supposed to mean) or is the search a complete waste of time? What will it be? Worlds full of shoppers and celebrities, biological constructions so unfamiliar that they are only brought home by accident and then inadvertently handed over for curation in a department of mineralogy or an exercise in galactic futility as one sterile world after another rolls beneath the spaceship windows. …

Given the likely range of planetary environments, such as a 100 km deep ocean or an atmosphere substantially denser than that of Venus, what fraction of any potentially habitable biosphere is actually occupied? Is the terrestrial ‘habitation box’ only a small proportion of all of biological occupancy space or, alternatively,has life here more or less reached the limits of what is possible anywhere? …

What we find here, therefore, will be a reliable guide to what we will find anywhere. Paradoxically, confidence that this may be correct comes from the dramatic increase in our knowledge of so-called extremophiles. … It may be that the current thermal limit (ca 120◦ C) of microbial activity [10] may not be much exceeded. In part, this is because water at this temperature is necessarily pressurized, and the equivalent limits of microbial habitation in the Earth’s crust (e.g. [11,12]) may not exceed ca 5 km (equivalent to ca 110 MPa; see also below) and an ambient temperature (depending on the local geothermal gradient) of at least 120◦ C. … While the environmental extremes of these and a few other multicellular organisms are impressive [18], the overall size of the habitation box for eukaryotes is unsurprisingly substantially smaller than that of life as a whole. … For life as a whole, there may be no lower limit in as much as at increasingly lower temperatures normal growth then yields to physiological maintenance, and ultimately dormancy where ‘coincidentally’ rates of DNA and protein repair are equal to those of macromolecular deterioration. …

A more fundamental question, however, is whether because of locally contingent circumstances terrestrial life just happens to occupy some fraction, perhaps very small, of the total carbaquist habitation box. As we have already seen, however, in the case of minimum temperatures, pH range, salinities and desiccation, arguably the defined limits for all carbaquists have been reached by life on Earth, and with somewhat less certainty this applies also to hyperthermophiles. …  there is little evidence of microbial viability significantly in excess of the tolerances seen in terrestrial piezophiles. … Given that at least in terms of carbaquist life it is likely that lipid membranes are universal, this suggests that viability may not extend much beyond the deepest oceanic trenches (ca 11 km) or equivalent pressure zone within the crust of the Earth (ca 5 km). But the viability of lipids is not the only problem. Another potential constraint of the habitation box is the behaviour under different temperature and pressure regimes of hydration water essential to biomolecular function. Not only is the optimal zone remarkably narrow, with that for temperature being curiously coincidental in both micro-organisms and homeotherms (ca 36–44◦ C), but the phase diagram for hydration water is circumscribed and little larger than the terrestrial habitation box.

A life-form … based on mirror-image versions of earthly proteins and DNA. … If it worked, those new cells … might also open up new avenues of discovery in materials science, fuel synthesis, and pharmaceutical research. On the down side, though, mirror life wouldn’t have any predators or diseases to limit its reproduction. …

A catastrophe was under way across the Charles River at Genzyme, one of the largest biotech companies in the world. … A virus that disrupts cell reproduction infected one of the bioreactors. The entire plant had to be shut down. … When Church talks about mirror life’s quirky advantages, invulnerability to this kind of mishap is high on his list. “Viruses can’t touch a mirror cell,” … This makes mirror life a potential workhorse for biotech. … Church has been hacking the ribosome. … His plan is to make one that reads regular RNA transcripts of genes but can string together wrong-handed amino acids to form mirror proteins. … Church and his team have cracked the first step. … Last year his team got a synthetic ribosome to self-assemble and produce luciferase, the protein that makes fireflies glow. And he has a library of mutant ribosomes that have the right kind of sockets—they’ll accept mirror amino acids. This is where the money comes in. Some of the most valuable drugs are actually tiny proteins that include wrong-handed amino acids—like the immunosuppressant cyclosporine. To manufacture it, pharmaceutical companies have to rely on an inefficient and expensive fungus. A hacked ribosome modified to handle both normal and mirror amino acids could crank out the stuff on an industrial scale. …

Church thinks even bigger. A manufacturing ribosome would be great, but a fully domesticated mirror cell—able to synthesize more-complicated stuff—would change everything. … vats of virus-proof mirror cells could pump out biofuel, lay down nano-size organic circuitry, and even extrude organic cement foundations for skyscrapers. …

Of course, mirror life could also kill us all. … Just as viruses from our side of the mirror can’t infect it, mirror pathogens can’t infect us. … They might be poisonous, though. … To a mirror cell, … there’s just not enough nutrition for them in the wild. … On the other hand, if mirror cells somehow evolved—or were engineered—to consume normal fats, sugars, and proteins, we might have a problem. … Mirror cells would slowly convert edible matter into more of themselves. … If mirror cells acquired the ability to photosynthesize, we’d be screwed. … All it would take would be a droplet of mirror cyanobacteria squirted into the ocean. Cyanobacteria are at the base of the ocean’s food pyramid, converting sunlight and carbon dioxide into more of themselves … That would wipe out the global ocean ecology. …

“I would be the first to say that we shouldn’t make a photosynthetic mirror cell,” Church says. “But I’m reluctant to have a moratorium on something that doesn’t exist yet.” He says he’d build safeguards into his mirror cells so they’d perish without constant care. And the advances in synthetic biology required to transform those first delicate mirror cells into anything that could survive in the wild are even more remote.

In many folks eyes, an elegantly simple resolution, which is likely because of its simplicity, is to assume there is just one huge filter: the origin of life. Assuming that first step is enormously hard allows one to think all the other steps are pretty easy. They wouldn’t be sure things of course, but conditional on a big enough origin-of-life filter, one wouldn’t have a strong reason to fear that common analyses underestimate future filters.

Unfortunately, the elegantly simple hypothesis that the great filter is mainly a big origin-of-life filter seems at odds with our best evidence. Why? Because if the spread-of-life step had the weakest possible associated filter, then life spreading must be easy. Over billions of years life could have spread to many star systems from its place of origin:

Life could spread across a galaxy via giant molecular clouds reliably collecting life from the stars they drift near, and then passing that life on to a few of the thousands of new stars they create.

If over billions of years life spread to many hundreds, or even billions, of star systems, and no substantial filters stood between arrival of life near a star, and its eventual development of advanced technical civilizations like ours, then why would we now see no any evidence of other civilizations? Yes it is possible that we are the very first, but that hypothesis is of course unlikely by default.

It seems to me that if the great filter is to consist of just one big step, the only plausible possibility is the development of multi-cellular life. All the steps before that one seem able to spread to other star systems via single-celled life hidden in dust, and it seems we haven’t had a big filter step since the multi-cellular innovation.

So if the idea of just one big filter appeals to your sense of elegance, you’ll have to presume that life, including complex life with sexual reproduction etc., is very common in our vast universe, but that Earth is one of the handful of places in all that vastness with multi-cellular life.

If you don’t find that plausible, well then you’ll have to grant there are at least two filters. And if two, why not three? So you must find the possibility of a third filter in our future plausible; beware future filters.

Now these stages could be of quite different difficulties, taking quite different unconditional expected times to complete.  But back in ’98 I noticed (and posted) an interesting non-intuitive result: if each stage is “exponential,” with a constant per time chance c to jump to the next level, then all “hard step” durations are similarly distributed, no matter what their relative difficulty.  (Joint step times are drawn from a uniform distribution.)  So we should see a history of roughly equally spaced hard step transition events in Earth’s history.

Prof. David J. Aldous, of U.C. Berkeley Dept. of Statistics, has just posted some generalizations of this result. While my result generalizes trivially to any per time success chance function C(t) that is nearly a constant C(t) = c near t=0, Aldous also generalized my similarly-distributed result to any function that is nearly linear C(t) = c*t near t=0.  He also generalized my result to any arbitrary tree of possible paths.  Each link in the tree can have arbitrarily varying difficulty, at each node in the tree many processes compete to be the first to succeed, and the one that wins this contest determines the system’s direction in the tree.

While Aldous warns us against over-reliance on simple models, this does I think gives a bit more reason to expect our history to consist of a sequence of roughly equally spaced hard step transitions.

Paul Davies, chair of the group that decides what SETI scientists will do if evidence of aliens is ever found, thinks … until scientists can say something to the public with great (~99%) confidence, they should say nothing. … Most early low-probability signs … being false alarms is “damaging to the credibility of science.”  So until scientists can confidently say that an asteroid will hit us or that we see aliens, they should just whisper to each other. … One might justify this confidence-or-silence policy by arguing … reporters are biased to present low probability news as if it were high probability.

Today’s Post:

NASA … reopened a 14-year-old controversy, … reaffirming and offering support for its widely challenged assertion that a 4-billion-year-old meteorite that landed thousands of years ago on Antarctica shows evidence of microscopic life on Mars. … Fourteen years of relentless criticism have turned many scientists against the McKay results, and the Mars meteorite “discovery” has remained an unresolved and somewhat awkward issue.  This has continued even though the team’s central finding — that Mars once had living creatures — has gained broad acceptance. …

Critics had said that the magnetites could have just as easily existed without bacteria or biology — that they sometimes form as a result of the shock and searing heat that could come, for instance, from an asteroid strike. But … [a] recent paper … reported that the purity of the magnetites made that explanation impossible. … “All the criticisms of our original paper got widely distributed, but when we did the work to prove the critics were wrong, it hardly made a ripple. … We’re now in a position to say we’ve knocked down all the criticisms — and our biological explanation is the one left standing.” …

At the conference, a leading cautionary voice in astrobiology proposed that a special protocol be established to oversee release of any journal articles making dramatic extraterrestrial claims. Andrew Steele … compared the absence of astrobiology review with the formal procedures set up by scientists involved with the search for extraterrestrial life, or SETI.  He said that SETI leaders understood the societal sensitivity of their work and that it was time for researchers in astrobiology “grow up and do the same.” (more)

Yet another voice for muzzling!  It seems clear to me that scientists do not usually insist on such high standards of confidence for publication.  Most Research Findings Are False seems pretty clear evidence, as does the high rate of celebrated new medical treatments that are later repudiated, and the very low marginal health-effectiveness of medicine.  I suspect I see similarly low standards for publications that are pro-global warming, or that warn of low science funding or manpower.  If the standard of evidence for publication varies with the topic, we can’t explain it via a generic tendency for reporters to exaggerate findings.  So what explains this variation?

Here I’ll channel Tyler Cowen, and suggest this is mostly about how real events echoing stories we tell change which intellectuals get more status.  Think of all the movies you’ve ever seen of an outsider intellectual unfairly rejected by establishment scientists.  Evidence of aliens, or a Really Big Disaster are prototypical.  Well establishment scientists see those movies too, and they don’t want real stories like them to appear in the media. They correctly perceive, for example, that a story confirming aliens would raise the status of UFO nuts, relative to establishment academics.  Similarly, news about a really big disaster would raise the status of “the sky is falling” outsiders.

On the other hand, establishment academics correctly perceive their status would be raised, relative to outsiders, by more stories of promising new medical treatments, of the seriousness of global warming, of the need for more science funding, or that a new result “might lead to a new theory of everything.” Even if such stories turn out later to be wrong.  Why?  Because we hear many similar stories about heroic scientists discovering treatments, or warning of enviro disaster, and few stories about such scientists being later wrong.

I see two effects:

1. There are some long standing disagreements between insider and outsider intellectuals in our society, and any news that confirms outsider claims raises outsider status.
2. News about a real event about you that matches a commonly-told story in which you’d be a hero, raises your status.   If that news is later reversed, that won’t reverse your status, if there aren’t commonly told stories about you being a villain in a news reversal story.