Sandy Pentland: Honest Signals

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Chris Hibbert

Sandy Pentland's Honest Signals talks about subliminal cues we all emit and makes a case that they provide reliable clues about all kinds of social outcomes. It's a quick read (100 pages of text, 50 pages of Social Science appendices, 30 pages of notes, bibliography and index) and makes a reasonably compelling case that our unwitting signals accurately foretell outcomes in many situations. (negotiation, sales, poker and dating were all studied.) The cues themselves are described in the appendices, along with a discussion of the gropus who have learned to read them (salespeople, poker players). Pentland says it will soon be possible to produce portable devices to make the signals evident. Some of the experiments he reports on were done using prototype portable units, others were done in the lab with earlier versions.

Several important questions aren't covered in the book: Why do we signal this way but not notice it consciously?, How could we effectively learn to detect these signals?, Can people learn to change the signals they produce (either to conceal their motivations, or to steer situations to more desirable outcomes)?

Pentland does show that there's reasonable evidence that the signals occur early in a conversation, that they are reliable, and that most participants don't notice the signals, even though they usually realize how things went for them by the end of a meeting. He tries to argue that we can use the predictions made about job satisfaction and organizational stress to optimize the way work groups are managed, but there is little indication that the tools can be used for steering. When the metrics show that information isn't flowing freely across a geographical boundary within a group, there are obvious things to do to change that, but is there an obvious response if they indicate that one person has more influence than others? Maybe making diagnostic information about the form of the interactions visibly shared within a group would make it possible for someone to intervene, but we're a long way away at this point from knowing how to optimally intervene in group politics or communication.

Neal Gershenfeld: Programming Bits and Atoms

I followed a pointer from the Long Now Blog to The Perimeter Institute's Quantum to Cosmos Festival, and found some interesting talks. I enjoyed listening to Lee Smolin talking to Neal Stephenson and Jaron Lanier about how science informs and learns from fiction. But I had a much stronger reaction to Neil Gershenfeld's talk on what he's been doing at the Center for Bits and Atoms. It involves multi-scale parallel computronium, and fabricators in the hands of kids all over the world who are vaulting past us in understanding what it means to build stuff with embedded intelligence. A fascinating talk.

Stephen Ziliak and Deirdre McCloskey: The Cult of Statistical Significance

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Chris Hibbert

Stephen Ziliak and Deirdre McCloskey's The Cult of Statistical Significance is a poorly argued rant about what appears to be an important topic on the pursuit of scientific knowledge. Ziliak and McCloskey argue that many of the statistical sciences have been using the wrong metric to determine whether the results of experiments are interesting and relevant. They report on a few detailed reviews of articles in top journals in economics, psychology, and other fields to show that the problem they describe is real and pervasive. Unfortunately, they are much more interested in casting aspersions on the work and influence of Ronald Fisher and building up his colleague William Gosset, and so they don't actually explain how to apply their preferred approach. In amongst the rant, they do manage to make the defects of Fisher's approach clear, though it's tedious reading.

The basic story is that Fisher argued that the main point of science is establishing what we know, and to that end, the important result of any scientific experiment is a clear statement of whether the results are statistically significant. According to Fisher, that tells you what confidence you should have that the results would be repeated if you ran the experiment again. Ziliak and McCloskey want you to understand that a result can be statistically significant but practically useless. And there are worse cases, where statistical significance and Fisher's approach leads scientists to hide more relevant results, or worse to conclude that a proposal was ineffective when the data show that a large effect might be present, but the experiment failed to show that it was certain. Ziliak and McCloskey want scientists to primarily report the size of the effects they find, and their confidence in the result. To Ziliak and McCloskey, a large effect discovered in noisy data is far more important than a small effect in very clear data. They point out that with a large enough sample, every effect will be statistically significant. (Though they don't explain this point in any detail, nor give any numbers on what "large enough" means. I have an intuitive feeling for why this might be true, but this was just one of many points that wasn't presented clearly.)

They describe a few stories in detail to show the consequences for public policy. Vioxx was approved, they claim, because the tests of statistical significance allowed the scientists to fudge their results sufficiently to hide the deleterious effects. (It's not clear why this should be blamed on statistical significance rather than corruption.) They also present a case that a study of unemployment insurance in Illinois found a large effect ($4.29 in benefit for every dollar spent), but gave the Fisherian conclusion, not just that the result wasn't statistically significant, but that there was no effect. It turned out that a careful review of the data showed that the program had a statistically significant benefit-cost ratio of $7.07 for white women, but the overall benefit-cost ratio was not statistically significant because the $4.29 was only statistically significant at the .12 level, while under .05 or less is required by Fisher's followers.

Ziliak and McCloskey demonstrate that they're on the right side of the epistemological debate by supporting the use of Bayes' Law in describing scientific results, but beyond one example, they don't explain how a scientific paper should use it in presenting results. The use of Fisher's approach gives a clear guide: describe some hypotheses, perform some tests, finally analyze the results to show which relationships are significant. With Bayes, the reasoning, approach and explanation are more complicated; but Ziliak and McCloskey don't tell how to do it. Of the 29 references to Bayesian Theory in the index, 24 of them have descriptions like "Feynman advocates ...", or "Orthodox Fisherians oppose ...". There aren't any examples of how one might write a conclusion to a paper and show Bayesian reasoning, even though they pervasively give examples of analogous Fisherian reasoning that they find unacceptable.

Another significance question that Ziliak and McCloskey argue is important (but that they don't explain adequately) and that statistical significance hides is how much various treatments or alternate policy approaches might cost. Fisher's approach allows authors to publish that some proposal would have a statistically significant effect on a societal problem or the course of a disease and not mention that the cost is exorbitant and the effect small (though likely). Ziliak and McCloskey argue that journal editors should require authors to publish the magnitude of any effects and a comparison of costs and benefits. According to the reviews they've done and others they cite, it's common in top journals to omit this level of detail and to focus on whether experimental results are significantly different from zero.

Another of the authors' pet peeves is "testing for difference from zero". They claim that it's common for papers to report results as "statistically different from zero", when they're barely so. They use the epithet "sign testing" for this case. The lack of attention to the size of an effect that significance testing allows means that papers get published showing that some effects have a positive effect on a problem, even when the effect is barely different from a placebo. And there are enough scientists performing enough experiments today that many treatments with no real effect will reach this level of significance purely by chance.

Overall, the book spends far too much time on personalities and politics. Even when the discussion is substantive, too much effort goes into why the standard approach is mistaken and far too little on how to do science right, or why their preferred approaches would actually lead to better science.

For the layperson trying to follow the progress of science, and occasionally to dip into the literature to make a decision about what treatment to recommend to a family member or what supplements would best enhance longevity or health, the point is that scientific papers have to be read more carefully. Ziliak and McCloskey argue that editors, even of prestigious journals, are using the wrong metrics in choosing what papers to accept, and often pressure authors to present their results in formats that aren't useful for this purpose.

When reading papers, concentrate on the size and the costs of the effects being described. Significance can be relevant, but the fact that a paper appeared in a major publication doesn't mean that the effects being described are important or useful. Don't be surprised if the most-cited papers in some area don't actually present the circumstances in which an intervention would be useful. Don't assume that all "significant" effects are relevant or strong.

James Flynn: What is Intelligence?

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Chris Hibbert

In his new book, What is Intelligence?, James Flynn tries to explain a few things. First he wants to explain what intelligence is and what its components are, second he wants to explain his new understanding of the Flynn effect, and what it implies about genes and intelligence, and thirdly, he wants to convince us that what The Bell Curve said about intelligence and race isn't supported by these new understandings. He succeeds admirably at the latter two; his success in explaining the nature of intelligence is limited.

For anyone who isn't familiar with the Flynn Effect, I'll repeat the findings briefly. More than two decades ago, Flynn noticed that IQs have been going up over time. About 3-5 points per decade, independent of culture, location, sex and race. The people who write intelligence tests have known for quite a while; they reissue their tests every decade or so, and "re-norm" the results. Since the definition of IQ is that 100 is the average score across the population (which population? That's a separate question; read the book if you want the details) they have to measure the results for a standardized group, and set the scoring so the current test will give the right results.

One of the consequences that matters to Flynn is the implication for death penalty cases, which he has been brought into recently. The implication is that if you give someone a test that is 10 to 15 years out of date, their score will be artificially inflated, since they are being measured by the norms of an earlier period. The obvious argument among defenders of capital cases is that death row inmates should be tested by up-to-date standards so as not to inflate their scores and accidentally rate them as competent to stand trial when they are in fact borderline or below it. Flynn points out that it's common for schools in disadvantaged areas and for prisons to not replace their existing stock of test booklets when a revision is issued, so they can be significantly out-of-date, which artificially inflates the scores and negates one escape route.

Like all good scientific revolutions, Flynn starts with four paradoxes arising from the combined data about rising scores.

• Different sub-tests (e.g. vocabulary, spatial reasoning, abstract analogies, pattern matching) have shown different increases. What's different about the areas in which intelligence is growing the fastest?
• Given the size of the increase, why doesn't it seem clear in everyday interactions that each generation is significantly smarter? 20 years is almost 10 IQ points, so two generations is nearly 20.
• How did our ancestors get by if only 100 years ago, everyone was mentally retarded by current standards?
• The changes are so rapid that they can't be genetic, so they must be due to environmental changes, yet studies comparing twins raised together and apart show that environment makes little difference to adult intelligence. Why does the environment make so much difference in some cases and so little in others?

Flynn's resolution is that the environmental differences that matter are large-scale and societal. He also argues that the societal differences compound, so even though small changes are scattered throughout our schooling, entertainment, child-rearing practices, employment expectations, and hobbies, the effects can be pervasive. The area of change that Flynn pinpoints is reliance on abstraction. This turns out to be a common thread among the sub-tests with the highest increases. Our ancestors dealt with the world much more concretely, and modern child rearing, education and entertainment all exercise our growing competence at abstraction. The results from twin studies are dominated by society-wide practices, and show that which family one is raised in, or which schools one goes to don't matter nearly as much as which era, and which society. An agrarian society that doesn't expect its children to grow up and leave the farm raises them to focus on the here and now. Expectations change when horizons open up, and we should expect every society to undergo a Flynn effect as people expect the next generation to live in cities, work in information-intensive jobs, and socialize with people who aren't all doing the same work their ancestors have done since time immemorial.

Ultimately, Flynn's book provides a satisfying resolution to the problems raised by IQ differences. The implications of Murray and Herrnstein's The Bell Curve for racial differences have been neutralized. Not by ethical arguments or posturing, but by a careful analysis of the data. Murray and Herrnstein were led astray by the surface implications of the data when analyzed within generations. If they hadn't written up their analysis carefully and thoroughly, Flynn wouldn't have been impelled to revisit the data and produce a sounder conclusion. Murray and Herrnstein's conclusions weren't original with them; their contribution was their willingness to explain an unpopular idea carefully enough that its limitations would become visible when the right context became apparent.

Murray and Herrnstein's other conclusions still stand: modern societies do an extremely good job of separating out the (relatively small, we now know) within-generation differences in intelligence, and directing people to different pursuits and occupations. The consequences is a shortage of general problem solvers in areas where intelligence is less valuable, while our institutions evolved in circumstances where general problem solvers were widely distributed.

Sunny Auyang, How is Quantum Field Theory Possible?

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Chris Hibbert

Sunny Auyang's How is Quantum Field Theory Possible? is the densest and most difficult book I have actually read all the way through. There are sections that seem brilliantly written, and sections that seem absolutely opaque. All together, I didn't learn as much as I had hoped, but I did come to understand a few points about the way QFT suggests we view the world.

"Until now almost all philosophical investigation of quantum theories have either taken the concept of objectivity for granted or prescribed it as some external criterion, according to which the theories are judged. The judgments often deny the objectivity or even the possibility of microscopic knowledge. I adopt the opposite approach. I start with the premise that quantum field theory conveys knowledge of the microscopic world and regard the general meaning of objects as a question whose answer lies within the theory. This work asks quantum field theory to demonstrate its own objectivity by extracting and articulating the general concept of objects it embodies. We try to learn from it, not only the specifics of elementary particles, but also the general nature of the world and our status in it. What general conditions hold for us and the world we are in so that objects, classical and quantum, which are knowable through observations and experiments, constitute reality?"

A large proportion of the book is dedicated to explaining Kant's Categorical Framework, which I'm willing to summarize by saying that everything in the universe consists of objects and their properties, and relations between the objects and between the properties. Many philosophers of QFT have presented a vision of quantum reality in which the quantum objects don't have definite properties except at the moment of measurement. Auyang shows that this isn't the only possible interpretation. Auyang's major goal in writing this book may have been to rescue Kant's Categorical Framework.

"The world described by quantum theories is remote to sensory experiences and is different from the familiar classical world. There are scientific puzzles, such as what happens during the process of measurement. Quantum theories disallow certain questions that we habitually ask about physical things, for example, the moment when a radioactive atom decays. [...] The working interpretation of quantum theories, which physicists use in practice, invokes the concept of observed results as distinct from physical states. [...] These factors prompt many interpreters to adopt the phenomenalist position asserting that quantum objects have no definite property [...] the observer creates what he observes."

Auyang wants readers to see how the world-view she refers to as "Kant's Categorical Framework" applies not just to the classical world, but also to quantum reality. This contrasts with the view presented by many prominent interpreters of QFT, and understood in the popular lingo as "it tells us that there isn't any truth of the matter with respect to quantum objects." Auyang shows how the quantum world can be described in the same objective way as the real world. QFT doesn't undermine our belief that everything is built up out of objects, properties and relations.

"This work presents a parallel analysis of the conceptual structures of quantum field theory and our everyday thinking. I do not try to describe quantum phenomena in substantive classical terms or vice versa. I try to articulate the categorical framework of objective knowledge, of which quantum field theory is one instance and common sense another. The categorical framework enables us to match logically the formal structures of quantum theories and everyday thinking element by element. The structural fit illuminates their philosophical significance."

The main thing I learned about the shape of the universe is that it's improper to think of space-time as fundamental and of objects (and their properties and relations) as inhabiting a pre-existing space-time continuum. Instead, according to QFT, particles and space-time itself are emergent phenomena that arise from the interplay between fermions (matter fields) and bosons (interaction fields). I've seen Feynman diagrams many times before, but I don't remember seeing a statement as clear as Auyang's "In Feynman diagrams, a matter field is [...] represented by a straight line and an interaction field by a wavy line." Section 8 contains this gem along with a table of the fermions and bosons and how they combine to form the four basic interactions (gravity, electromagnetism, strong and weak forces). Auyang makes it clear that at the quantum level, the fundamental elements are the fermions and bosons, that bosons mediate all interactions between fermions, and that bosons and fermions are emergent phenomena of something more fundamental.

At the classical level, we're used to objects interacting directly: billiard balls collide and reflect in predictable directions. At the quantum level, bosons meditate the interactions between fermions. Photons, which are colloquially described as half-particles and half-wave aren't particles at all in this sense, they're the entities that mediate the electromagnetic force. Classical photons are just as much an emergent phenomena as electrons are, but they're part of the constellation of interaction fields while electrons are a kind of matter field. Auyang says "space-like separated transformations do not affect each other, for causality demands that physical effects propagate from point to point with finite velocity." That includes everything from billiard balls caroming to planets tugging on every body in the universe. (Though Auyang admits that "the gravitational interaction is not well understood.")

She goes on to explain how to think of the fields as exhausting space time:

Absolute positions are identities of events. There is no identity without an event. [...] Fields, which are spatio-temporally structured matter, exhaust the universe. It is not that the matter fills space-time; rather, the spatio-temporal structure spans the physical universe.

Auyang also attempts to explain (in § 16) how to think about QFT without invoking the consciousness of the observer. Her explanation seems plausible to me, but I'm not sure I ever understood why the standard model required a special status for the observer. Her explanation seems to boil down to arguing that the proponents of the Copenhagen interpretation are confused by the claim that quantum mechanics is a complete and final theory. (Apparently the term originates in the 1935 EPR paper.) According to Auyang, later proponents pushed the definition too far, insisting that observation required an observer. Auyang says that the observer is implicit, and to the extent that QM provides a complete theory, it's only a complete theory about quantum objects, so the observation has to be at the quantum, not classical level, in order to be part of the theory. I don't know whether theoretical physicists will accept her argument, but I think that's the interesting test of her argument.

While she is talking about the general concept of objects (§ 15), Auyang makes an observation that seems relevant beyond her intention. She says "When we look around, we see objects, books and pens. The presence of objects is immediate, we do not infer them from sense data." Her point is that we learn that our senses can be in error, and that objects we perceive may not actually be present (due to optical illusions, hallucinations, etc.). But the point is more fundamental: the process of coming to awareness is a process in which our sensory apparatus learns how to lump perceptions together based on in-built notions of permanence, cohesiveness, and various kinds of conservation rules. By the time we're doing anything that can be called thinking, we no longer have (if we ever did) access to raw perceptions; we think and perceive in terms of lumpy objects. Artists have to work hard to learn to see the colors, textures, and contours that make up an image. Greg Egan illustrated this brilliantly in a passage in his novel Diaspora. Jeff Hawkins' On Intelligence relies on the same effect at a different level.

Michael Lockwood: The Labyrinth of Time

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Chris Hibbert

Michael Lockwood's The Labyrinth of Time starts out as an explanation of the physical structure of time, but morphs gradually into a treatise on anything Lockwood is interested in that can be remotely connected to time. Lockwood's interests include time travel, quantum electrodynamics, black holes, and quantum gravity. His exposition is better in areas that are clearly physics, and worse on things like the meaning of causality and time travel.

Lockwood starts by presenting two basic ways of thinking about time. In one, the past is fixed and the future is mere possibility turning into the unchanging past as we move past it. The other says that both the past and future are fixed, our point of view is called the present, and as time passes, we get to watch a narrow slice of the fixed 4-dimensional reality pass by. Most of physics works equally well whichever direction time moves, and Lockwood wants to explain why the past and the future seem different to us. We remember the past and not the future. In the end, this paradox wasn't cleared up for me.

Lockwood does present some good new visualizations that clarify space-time and various "problems" with reasoning about the speed of light. His presentation of simultaneity, using a moving train car with two different observers was remarkably clear, as was his explanation of the twin paradox using two unaccelerated paths through a hypothetical cylindrically connected space-time. The presentations of the physics of black holes (and how to use a black hole as a power source) were also good, but I didn't get much out of his approaches to string theory or quantum gravity. I think part of it was that the presentations were more hurried nearer the end of the book; he did better when he took the time to explain the basic concepts clearly first before getting to the advanced ideas. I suspect that except for people steeped in these later areas, his explanations will come up short.

Lockwood kept coming back to time travel paradoxes, without ultimately resolving the issue. Apparently the standard interpretations of physics say that paradoxes aren't allowed, and the open question is what mechanism the universe will use to prevent them. Apparently, if you don't believe in many worlds, you are forced to believe that there is only one past and a single future that will eventualy unfold. This doesn't allow causal loops (even though the fundamental equations seems to countenance them) much less time travellers acting in the past to prevent their known futures from (re-)occuring. I think the underlying theories force you to accept a single past even if you don't go for many worlds. So, whether the past becomes fixed as we journey with the moving present, or our viewpoint moves across an already fixed landscape, you're stuck.

I don't see how these arguments would convince anyone that the universe would act to prevent closed time-like loops. Until we see events conspiring to prevent causal loops, I'm happier reconciling the claim that physics allows time travel by accepting that space-time may be a causal spiral than expecting the universe to allow time travel while conspiring subtly to prevent someone from killing her grandfather. But as Norm Hardy pointed out, some of the phyisicists who seem to understand the equations say that the equations force you to believe in an invariant past. And in the end, Einstein's ability to predict, based on the equations, a lot of what we now believe and that experiments have confirmed, says that that's a strong argument.

Peter McCluskey also wrote about Labyrinth.

Filed in: Reviews

Kanzi, Sue Savage-Rumbaugh

0.2 Chris Hibbert Kanzi: The Ape on the Verge of the Human Mind

Sue Savage-Rumbagh & Roger Lewin'sKanzi is an anecdotal presentation of the capabilities of modern, communicating apes, focusing on Kanzi, who has learned to use an ideograph-based keyboard. Savage-Rumbaugh relates many experiences that don't fit easily into the controlled scientific process in order to show us how much more capable Kanzi and his cousins are than the studies can demonstrate. At the end of it I'm fairly well convinced that Kanzi is communicating, has intentionality, has a mental model that includes the fact that others know different things than he does (sometimes more, sometimes less), can make plans, can and does lie, has a mental map of his (apparently large) normal range and can plan routes in it, and uses grammatic and semantic categories.

I think it is highly likely that these abilities are not shared with chimpanzees and bonobos in the wild, but that many of them would develop such skills if raised in appropriate environments. This conclusion isn't based directly on evidence that Savage-Rumbagh presents, but is my own deduction from the fact that more than a half dozen random individual chimps and bonobos have displayed similar talents when exposed to a variety of language tools more suited to their use than oral speech.

I'm not inclined to think that this changes the moral category of those species in toto, though it probably should have implications for how we treat the individuals that we have raised to such awareness. In order to justify drawing a line to include some chimps and bonobos as aware, and leave most as simple animals, I need to be clear about my thoughts about why we don't draw a similar line distinguishing normal humans from some subset that appears to be less aware than Kanzi. I think the argument that declaring some humans to be outside the protected boundary is a "slippery slope" is a good enough justification for treating all humans as if they were sapient. The difference in intellect between the chimps and bonobos who have acquired language and their kin who haven't is large enough that there's little hazard in drawing a line between them.

Savage-Rumbagh did most of her work in a lab that mainly focused on developmentally challenged clients. Some of the work with Kanzi suggested techniques for teaching them communication skills. These techniques turned out to help some of them significantly in mixing with their mainstream peers.

Filed in:

• Reviews
• Cognition
• Language

Charles Mann: 1491

0.2 Chris Hibbert 1491

Charles Mann's 1491 is a very interesting read. The main point is that the natives to the Americas were a lot more numerous and a lot more advanced before the arrival of the European adventurers than anyone realized until recently. Whatever you learned in school vastly underestimates the accomplishments and the scale of their civilizations. There are a lot of details still to be worked out, but that much seems clear.

Mann is very good at taking the discoveries and recent analysis and making the possibilities clear: there is disagreement in many cases about how many people were here, how much contact there was between groups, when and how they died off, and just how sophisticated they were, but at the end there is so much evidence that there was large-scale engineering in so many places (the North American Midwest, the Amazon basin, the Andes and along South America's west coast, and Central America) that the conclusion stands above the minor disagreements.

More than anything, it's an enjoyable read. Even though Mann is heaping up evidence, he tells good stories of how the people must have lived and struggled. He seems to make it clear when he is speculating, when the experts are in agreement on the basics, and when he is reporting on aspects of the history that are still in dispute. The North American natives didn't write anything down, so he can't tell many stories about individuals, but the South Americans had a variety of writing systems, so he's able to report on political struggles that demonstrate the extent of the civilizations and gives some hints about how the internal wars may have contributed to their demise in the face of the conquistadors and their diseases.

In all these areas, there are constructions that were large enough, and that have endured well enough that they are still visible if you know what to look for. Until recently, anthropologists and archaeologists didn't realize they were there, and so hadn't studied them. In the Andes and the western plains, there are dikes and large scale water works that have only been identified as such in the last twenty years. In the Midwest, there are humongous mounds that are clearly artificial. New pyramids have been discovered in the Amazon in the last twenty years using LIDAR that can penetrate the tree cover.

The mounds are a fascinating chapter all to themselves. My favorite is the Cahokia mound. Cahokia, near present day Saint Louis, was the largest (maybe the only?) city north of the Rio Grande for 300 years starting about 1000 years ago. They built a series of mounds, of which Monks Mound is the most interesting.

Its core is a slab of clay about 900 feet long, 650 feet wide, and more than 20 fee tall. From an engineering standpoint, clay should never be selected as the bearing material for a big earthen monument. Clay readily absorbs water, expanding as it does. The American Bottom clay can increase in volume by a factor of eight. Drying, it shrinks back to its original dimensions. Over time the heaving will destroy whatever is built on top of it.

To minimize instability, the Cahokians kept the slab at a constant moisture level: wet but not too wet. Moistening the clay was easy—capillary action will draw up water from the floodplain, which has a high water table. The trick is to stop evaporation from drying out the top. In an impressive display of engineering savvy, the Cahokians encapsulated the slab, sealing it off from the air by wrapping it in thin, alternating layers of sand and clay. [...] The final result covered almost fifteen acres and was the largest earthen structure in the Western Hemisphere: though built out of unsuitable material in a floodplain, it has stood for a thousand years.

The time of arrival of the pre-columbian inhabitants is more contentious than I realized. I've been using the figure of 13000 years before the present as the time that the first wave came over the Bering Strait, and wiped out all the mega-fauna. It appears that there were probably two waves of immigration before that, and possibly more, though the timing is completely unclear. There are indications that early humans were here as early as 30,000 years ago, and that there was another wave around 20000 years ago based on genealogical evidence and tantalizing archaeology. Those people didn't leave many artifacts, so there is still plenty of disagreement.

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• Reviews
• Anthropology

Levee Breaks

We went to the USGS (US Geological Survey) open house a week ago. The first thing we noticed was the sparse crowds. Hard to tell whether it was a lack of advertising or infelicitous scheduling as one scientist told us.

The best part of the open house is that the scientists-the lead investigators-are standing by their posters, eager to talk about the details and the implications. Janet and I talked for quite a while with a woman whose poster was about invasive species in the Sacramento delta and their effects on the levees. She was impressed by my story from Science News about an approach to controlling the zebra mussels but pointed out that it wouldn't work in open water.

She has been tracking the spread of the mitten crabs. They're a fresh water species, so the spread has been coming overland. A few miles at a time. Occasionally by intentional human intervention. The people trying to hold the crabs back currently have a line drawn, and seem to be holding it for now, though it's not clear how long it will last.

We also talked about the robustness and stability of the levee system in the delta. The delta is an unusual system, since it's a mix of fresh and salt water. The tides push the salt water in an out a certain distance every day. Above the level that the salt never reaches, but still within the delta, is where the aquaducts (which feed the central valley and LA) start. If the levees break above the aquaduct feeds, the increased water draw could pull salt water further up into the delta in a way that would be impossible (or at least horribly expensive) to repair.

The most surprising thing she told us was that the farm land behind the levees has subsided. (See the google or terraserver maps for a browsable view of the delta.) The land here was originally peat. As it has been farmed, it has gradually lost a lot of volume. When the levee system was built, the farmland was at or above the level of the river. The levees were built a few feet high to hold back the water. But the land has now subsided up to 20 feet in most places. (Janet and I drove through here, geocaching, on our way to visit her father a few years ago. We saw that the levees were much higher than the farmland, but didn't realize that the water was close to the top of the levees.)

When the levees break, the water rushes in, and can be infeasible to pump back out. Look at the satellite views again. The large areas the same gray as the river were inundated in the 80's, and after a short struggle, California gave up on trying to dry them out. The narrow green line surrounding the newmade lakes but inset from the edges are the old levees. Current worries are invasive species undermining the levees, general lack of maintenance, and the assurance that eventually there will be an earthquake.

USGS Open House June 3rd and fourth

The USGS rotates annual Open Houses among its three major research centers (Menlo Park, California; Northern Virginia; and Boulder, Colorado), and this year it's the Bay Area's turn again. This is great fun for anyone who enjoys science or has inquisitive kids. They put on a great show with lots of exhibits staffed by the USGS scientists who have been doing original research. They do geology, weather monitoring, oceanography, astronomy, and much more. Their mappers develop great maps showing many different views of the US (geography, politics, rock formations, earthquakes, gravity variation, etc.) plus maps of other planets and the sky. There's always plenty of interesting things to see, and people present who understand the science, can explain it well, and are excited about sharing it with the public. Great fun!

Attacking Zebra Mussels

A new approach to attacking invasive species, according to Science News. Chemists and zoologists at the University of Cambridge have invented an approach to reducing the number of Zebra Mussels in locations like water supply pipes where they're an expensive nuisance. The twin problems with attacking filter feeders are that they shut down their feeding when they detect toxins, and that high levels of toxin will likely afffect other organisms. In this case, they coated small particles of a toxic substance (potassium chloride) in a benign and degradable coating (vegetable oil and soap). Filter feeders accept and concentrate the particles, and are eventually poisoned. The coating degrades in a couple of hours, and once dispersed, potassium chloride (sometimes used as a salt substitute) is relatively harmless.

Fear of Flying

I'm a skeptic when the flight attendants ask passengers to turn off their electronic devices. Years ago, I saw a reference to an IEEE Spectrum article that apparently provided the justification for the airlines' paranoia on the subject, and so I tracked down and read the article. My recollection of the article is that it contained only a hypothetical mechanism by which electronic devices inside the airplane could radiate through the skin, and resonate depending on the specific surface geometry of the airframe. In some cases, the signal might be picked up by external antennas serving the plane's navigation systems. The article (as I remember it) didn't mention any concrete cases, so I discounted it.

For many years, my practice has been to turn on my iPod (previously the CD Player) once I was settled in my seat, and not turn it off unless an attendant noticed that I had it on and directly told me to turn it off. If the pilot noticed interference, I reasoned, she could ask the passengers to turn stuff off, and I'd happily comply. (I can see why cell phones and wireless devices would be a problem, but why would a CD Player be radiating significant amounts of RF interference?) If they couldn't tell that anything was happening, I believed, it must have been all superstition on the part of the airline industry. After all, they've given us plenty of reason to believe that if they can blame the rules on someone else, they are completely unconcerned about inconveniencing us, and little reason to believe that the safety rules are updated when conditions change. (Have you noticed that they're still explaining how seat belts work? How long has it been since you could assume that 99.99% of potential passengers were familiar with seat belts?)

The Mercury News had an article a few days ago saying that there was a new study showing that Cell Phones are causing interference. As usual, there's not enough information in the article to tell what the study looked at or how significant the results were, so I googled for the new article. The authors are mostly worried about the proposals that cell phone use be allowed in flight, but they also mentioned a telling incident involving a DVD player. The most alarming fact in the article, though is that the Aviation Safety Reporting System database that used to track anonymous reports of safety problems reported by crew members or the public has discontinued some services due to budget cuts.

I'm not particularly a fan off more government reporting and regulation, but when they've crowded out private alternatives, it can be dangerous to drop the government funded programs.

Back to the errant DVD player. The new article reported:

In one telling incident, a flight crew stated that a 30-degree navigation error was immediately corrected after a passenger turned off a DVD player and that the error re-occurred when the curious crew asked the passenger to switch the player on again. Game electronics and laptops were the culprits in other reports in which the crew verified in the same way that a particular PED caused erratic navigation indications.

This was the kind of specific detail that I've been claiming for a while was missing in the previous article, and which would have been convincing. So I went back to look at the older article. This looks like the article I found back then, but it does report specific incidents quite similar to this one:

A report selected from the ASRS database illustrates this type of incident. In March 1993, a large passenger aircraft was at cruise altitude just outside the Dallas-Fort Worth International Airport when the No. 1 compass suddenly precessed IO degrees to the right. The first flight attendant was asked to check whether any passengers were operating electronic devices. She said that a passenger in seat X had just turned on his laptop computer.

The report continues: "I asked that the passenger turn off his laptop computer for a period of 10 minutes, which he did. I then slaved the No. 1 compass, and it returned to normal operation for the 10 minute period. I then asked that the passenger tum on his computer once again. The No. 1 compass immediately precessed 8 degrees to the right. The computer was then turned off for a 30-minute period during which the No. 1 compass operation was verified as normal.

Whoops. Well, nowadays, I use an iPod, and it's hard for me to imagine that they radiate as much RF as a PC or even a DVD player. But I may start turning it off for landings, which is what the experts seem most concerned about.

Here are some more excerpts from Spectrum:

All in all, we found 125 entries in the ASRS database that reported PED interference. Of these, 77 were considered highly correlated, based on the description of observed PED use and interference occurrence. The reports included cases of critical aircraft systems such as navigation and throttle settings being affected. Based on the random sample entries from 1995 to 2001, we estimate that the average number of reported interference events might be as high as 23 per year. There is considerable uncertainty about how many incidents actually occur in a year; a number of factors could make the number higher-or even lower-than the estimate of 23. Some reported incidents have not been entered into the database, and some of the reported incidents may not be interference events (that is, they might be false positives). But the data certainly suggest that PED interference events occur a few times each month.

At present, we believe that passenger use of electronics on board commercial aircraft should continue to be limited and that passengers should not be allowed to operate intentionally radiating devices such as cellphones and wireless computer equipment during critical stages of flight.

The practice of including an identifiable random sample of incidents was dropped (because of budget cuts), the ASRS can no longer be used to do statistically valid studies of all types of incidents, including those involving PED interference. Congress should provide budgetary support to reinstate the random sample entries or, better yet, to enter all the received reports.

Isn't this something the airline industry should fund privately if the government is letting the ball drop?

Slow light again

Remember Mercury Delay lines ? No, I wasn't there at the time, but it's an odd bit of technology that hackers like to tell one another about. The UNIVAC I (and other early computers) used this technique to store electronic pulses of information to be used later. The basic idea (and metaphor to be emulated) is that you find a way to send bits out on a slow loop so they'll return at a known time in the future when you'll be ready to use them again. Originally used in WWII radar to remove static objects from images, they were eventually used as generic (short-term) memory.

Well there's new work on slowing down the speed of light that may bring this metaphor in reach again. Remember in 1999, when scientists used clouds of ultracold sodium gas in a Bose-Einstein condensate to slow light down to "walking speed"? Well, the current work uses a silicon crystal full of holes to slow the light. When they send small currents through the crystal, temperature changes in the crystal vary the delay that is applied to the passing light. This means they can vary the delay, making the delay lines more versatile.

Everything Old is New Again.

Rocket Racing League

It sounds like science fiction, and I haven't read about it in the newspaper or any of the blogs I read regularly, but the BBC and several other media outlets are reporting on it, so it must be true. Peter Diamandis, the money behind the X-prize, which encouraged more than a half dozen teams to work on development of vehicles that could safely and repeatedly reach the edge of space, has announced the next step in private space development. He's starting the Rocket Racing League, a race series that will bring exciting competitive rocket races to airports around the country and eventually around the world.

They had a public demonstration at the X Prize Cup and Personal Spaceflight Expo in Las Cruces at the beginning of October, and later in the month showcased a test flight of the EZ-Rocket:

October 21, 2005 - The Rocket Racing League™, announced the successful completion of a detailed performance flight test research program for the EZ-Rocket rocket plane culminating in two exciting and aggressive public demonstration flights. The EZ-Rocket, precursor to the X-Racer™ now under development, made three flights out of Las Cruces, NM at the 2005 X PRIZE Cup events, two of these on the same day. The flights included three successful engine relights during flight and a maximum altitude reached of 8,756 feet. This accomplishment is a significant milestone for the vehicle and for the Rocket Racing League.

The point (obviously?) is to get people excited about space development. The league will fund develpment and production of ten initial rockets. The first few should be able to start racing in 2006, and the full fleet should be going in 2007. Diamandis hopes that other groups will develop their own rockets and enter them in the series. The rockets will be operated by independent companies, and will compete for a final cup annually in New Mexico.

I think these guys have the right idea. It will only take a few billionaires to put enough money into developing visible civilian applications of space to move development forward far enough that space development will be commercially viable. And making it sexy and exciting, and apparently dangerous will attract attention. The Rocket Races will look edge-of-your-seat scary, but if they can keep it actually safe, people will be happy to take trips to space, and spend time in space hotels.

And that'll lead to enough serious development that more commercial applications will become affordable, and other uses will drive development of yet more vehicles and technology.

Filed in: Space