Links for December 2015

We study the extent to which eminent scientists shape the vitality of their fields by examining entry rates into the fields of 452 academic life scientists who pass away while at the peak of their scientific abilities. Key to our analyses is a novel way to delineate boundaries around scientific fields by appealing solely to intellectual linkages between scientists and their publications, rather than collaboration or co-citation patterns. Consistent with previous research, the flow of articles by collaborators into affected fields decreases precipitously after the death of a star scientist (relative to control fields). In contrast, we find that the flow of articles by non-collaborators increases by 8% on average. These additional contributions are disproportionately likely to be highly cited. They are also more likely to be authored by scientists who were not previously active in the deceased superstar’s field. Overall, these results suggest that outsiders are reluctant to challenge leadership within a field when the star is alive and that a number of barriers may constrain entry even after she is gone. Intellectual, social, and resource barriers all impede entry, with outsiders only entering subfields that offer a less hostile landscape for the support and acceptance of “foreign” ideas.

(H/t Robin Hanson.)

Which saddens me, as an MWI proponent, because I am very quick to admit that there are potentially quite good objections to MWI, and I would much rather spend my time discussing those, rather than the silly ones. Despite my efforts and those of others, it’s certainly possible that we don’t have the right understanding of probability in the theory, or why it’s a theory of probability at all. Similarly, despite the efforts of Zurek and others, we don’t have an absolutely airtight understanding of why we see apparent collapses into certain states and not others. Heck, you might be unconvinced that the above postulates really do lead to the existence of distinct worlds, despite the standard decoherence analysis; that would be great, I’d love to see the argument, it might lead to a productive scientific conversation. Should we be worried that decoherence is only an approximate process? How do we pick out quasi-classical realms and histories? Do we, in fact, need a bit more structure than the bare-bones axioms listed above, perhaps something that picks out a preferred set of observables?

Within the consistent histories formalism, this issue manifests as Kent’s set selection problem, as I have belabored many times before.

Many online platforms such as Yahoo! Answers and GitHub rely on users to voluntarily provide content. What motivates users to contribute content for free however is not well understood. In this paper, we use a revealed preference approach to show that career concerns play an important role in user contributions to Stack Overflow, the largest online Q&A community. We investigate how activities that can enhance a user’s reputation vary before and after the user finds a new job. We contrast this with activities that do not help in enhancing a user’s reputation. After finding a new job, users contribute 25% less in reputation-generating activity on Stack Overflow. By contrast, they reduce their non-reputation-generating activity by only 8% after finding a new job. These findings suggest that users contribute to Stack Overflow in part because they perceive this as a way to improve future employment prospects. We provide direct evidence against alternative explanations such as integer constraints, skills mismatch, and dynamic selection effects. The results also suggest that, beyond altruism, career concerns play an important role in explaining voluntary contributions on Stack Overflow.

(H/t Tyler Cowen.)

The cost of LIDAR, a key component of self-driving cars, is falling fast:
“Our customers are telling us they want it to be below $100, that’s kind of the roadmap we’re working from in the back of our mind,” Eggert said.

Velodyne is developing a sub-$500 LIDAR sensor, the VLP-32, that it says will be powerful enough for high-level assisted driving, and autonomous driving. (It declined to reveal exact technical specifications.) Velodyne has development contracts with two manufacturers, one in North America and one in Japan, to deliver the sensor in the first four months of 2016.

And the new sensor isn’t going to be a hulking piece of equipment either. It’s small enough that some players have expressed interest in putting the sensor in vehicle side mirrors. Others may put it on the roof, the easiest way to get a 360-degree view.

Quanergy chief executive Louay Edlada believes LIDAR will cost below $100 in five years. It’s releasing a solid state LIDAR — meaning none of the parts move — next month for $250.

While this proposal was developed by us at CSER (with collaboration from the ‘spokes’ at FHI etc), it will operate as a standalone centre physically, administratively, and in terms of funding, although the centres will collaborate closely. None of the funding will go to CSER.

There will be some differences, namely:

– Leverhulme CFI is broader in its focus on AI, encompassing a broader look at long-term opportunities and challenges of AI (“puerto rico agenda”, if you will), rather than CSER’s somewhat tighter focus on AI safety/risk, although safe and beneficial development of AI will be at its core. It won’t focus on other technologies (unless related, like neuro).

– CSER is broader in its focus on risk, encompassing e.g. bio risk, extreme climate, and future threats.

The plan we’ll be working to will be to develop long-term secure funding for both.

http://futureoflife.org/2015/12/03/15-million-granted-to-new-ai-research-center-at-cambridge-university/

Only 1 in 500 patents makes its inventor money, and businesses are awash in great ideas of dubious market value (only about 4% make money).1 So why do people think innovation begins with a creative idea, is sold through an imaginative story, and diffuses through society because of novelty and merit? Innovators mobilize people to adopt ideas. Although they might start with idea creation, innovators focus mostly on other aspects: market offers, market testing, beta prototyping, production, sales, and customer-support infrastructures that companies use to get products adopted. In fact, 90% of innovation is in fostering adoption.1,4 Ideas are often stories invented after the fact to explain innovations that already emerged, as with the iPhone example discussed later in this column. Yet the media telling of the story makes it sound as if ideation—the creation of ideas—is 90% of the work of innovation. Ideation has produced many inventions that never became innovations because no one adopted them. Many people are misled by stories that inaccurately equate innovation with invention. People who believe these stories put too little effort into adoption and are disappointed by their low success rates

(H/t Robin Hanson.)

After the matriarch died last year, a vicious battle erupted among the female baboons at the Toronto Zoo for her throne that endured for months, prompting a brief closure of the exhibit and providing a fascinating glimpse into the animals’ behaviour.

Medical records show numerous injuries among five of the six female olive baboons, from deep lacerations near their eyes to hair ripped out and tail injuries. At least two required surgeries to close deep gashes.

The exhibit was closed for several days because “there were some injuries that we thought best to keep them at the back because our visiting public don’t know baboon behaviour,” said Maria Franke, the curator of mammals at the zoo.

The baboon house — the area not open to the public where the animals eat and sleep — also had to be modified to allow for more space and additional escape routes, Franke said.

Now, Dutton said, two females sit on the throne in an uncomfortable truce, with the rightful heir biding her time until the older one dies.
Baboons, both in the wild and at zoos, have societies that are run by females — and that dominance runs through family lines. So the oldest daughter of the matriarch is the rightful heir to become queen.

In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. We report the discovery of such a system. In Hubble Space Telescope imaging, we have found four images of a single supernova forming an Einstein cross configuration around a redshift z = 0.54 elliptical galaxy in the MACS J1149.6+2223 cluster. The cluster’s gravitational potential also creates multiple images of the z = 1.49 spiral supernova host galaxy, and a future appearance of the supernova elsewhere in the cluster field is expected. The magnifications and staggered arrivals of the supernova images probe the cosmic expansion rate, as well as the distribution of matter in the galaxy and cluster lenses.

Presumably this supernova is too far away to be useful for neutrinos or anything like that.

The argument I hear against becoming overly worried about bacterial resistance induced by overuse of antibiotic is this: The cellular machinery bacteria must assemble to be resistant to antibiotics is metabolically costly. It’s true that the bacteria whose main environment is saturated with a certain antibiotic will eventually develop resistance, e.g. in bacteria moving from hospitalized human to hospitalized human, or bacterial living on farms which employ antibiotics. But as soon as you stop using the antibiotic routinely, the bacteria will naturally shed the resistant abilities because it’s energetically favorable to do so. (The article simply notes, without explanation: “In the end, though, VRSA turned out not to be much of a threat: In 15 years, there have been only 14 such infections in the United States.”)

One counterargument is this: assembling cellular machinery is indeed costly, but once the resistance mechanism has been cracked it’s relatively cheap to keep a copy of the instructions for doing so, either as some trace background level of plasmids, or as dormant DNA in bacteria that requires activations by external stressors from the antibiotic. Once the selection process, which is induced by rampant use of antibiotics, produces the instructions, these instructions can potentially lie dormant for very low cost. (A counter-counterargument is that even DNA has storage costs in the form of mutational load.)

I wish I knew how these argument are used by the experts, and whether there is consensus. I suspect that, like many similar policy concerns, this ultimately boils down to fights over how to wisely apply the precautionary principle.

Compared with most other astronomical objects, the ice and rock particles in Saturn’s rings are extremely close together. On average, about 3 percent of the total volume of the disk is occupied by solid particles, while the rest is empty space. This may sound small, but it means the typical separation between particles is only a little over three times their average diameter. Assuming a value of 30 centimeters for the latter, the rocks would be as close as one meter away from each other. There is no hard and fast rule, however, due to density variations across the rings and the wide spectrum of particle sizes.

That means that artistic depictions like this

are totally realistic! Rocks would range in size between dust grains and houses. The rings are between tens of meters to several kilometers thicks. If you were inside the ring, you would be weightless in a field of floating boulders. However, if you pushed off one and launched yourself on a slow trajectory out of the ring, you might rise above it, but then would slowly fall back down. The arc would take a few house (since ring orbit times are ~10 hours), and you would have a chance to stop your self by pushing off one of the boulders as you re-entered the ring.

It appears to us that the strongest scientific funders have little interest in policy analysis and advocacy, while the strongest funders of policy analysis and advocacy tend not to take interest in the scientific research issues discussed in this post. We’re interested in the idea of combining – in a dedicated organization – great scientists and great policy analysts, in order to put in the substantial amount of work needed to develop and promote the best possible proposals for improving science policy and infrastructure. It would be a high-risk, potentially very high-return project to attempt. We aren’t aware of any attempts to do something along these lines at the moment, and we think it could be a risk worth taking.

So far, we haven’t been able to find a person or organization who seems both qualified and willing to lead the creation of the sort of organization described in this post. We plan to continue looking for such a person or organization, while continuing to discuss, refine and reflect on these ideas.

Another reddit phenomenon is the AMAs, especially for non-celebrities. I utterly take these for granted now, but less than a decade ago it was an absolute revelation to get detailed, first person perspective on what its like to be in uncountable different roles. Reading the guy describe being a subway sandwich maker was fascinating. Who knew that, with all the hassles, low pay, and low status, he said the one thing he still liked about the job after years was…making sandwiches!

The spacecraft are aluminum-covered brass spheres with a diameter of 60 cm and masses of 400 and 411 kg, covered with 426 cube-corner retroreflectors, giving them the appearance of giant golf balls. 422 of the retroreflectors are made from fused silica glass, while the remaining 4 are made from germanium to obtain measurements in the infrared for experimental studies of reflectivity and satellite orientation. They have no on-board sensors or electronics, and are not attitude-controlled…They orbit at an altitude of 5,900 kilometres (3,700 mi), well above low earth orbit and well below geostationary orbit at orbital inclinations of 109.8 and 52.6 degrees…Measurements are made by transmitting pulsed laser beams from Earth ground stations to the satellites. The laser beams then return to Earth after hitting the reflecting surfaces; the travel times are precisely measured, permitting ground stations in different parts of the Earth to measure their separations to better than one inch in thousands of miles…The LAGEOS satellites make it possible to determine positions of points on the Earth with extremely high accuracy due to the stability of their orbits…The high mass-to-area ratio and the precise, stable (attitude-independent) geometry of the LAGEOS spacecraft, together with their extremely regular orbits, make these satellites the most precise position references available.