- Chris Blattman on the Center for Global Development’s endorsement of cash transfers. (Report.)
Here’s to several decades of grinding out a couple of decimal places to parameterize a charged Higgs:
Three years ago the BaBar collaboration at SLAC measured the branching ratios for B-meson decay to produce either a muon or a tau. For two slightly different decays, they found 2σ or greater deviations from the democratic standard-model expectation. Now the LHCb collaboration at CERN has confirmed the BaBar result for one of the decays. In a preprint, the Belle group at KEK in Japan has also announced results that show a similar though less strong deviation from the standard model. The figure below (from the Heavy Flavor Averaging Group) shows the branching ratios (R) measured by the groups for the two decays, denoted D and D*, along with the standard-model prediction. Taken together, the groups’ measurements have struck a 3.9-σ blow to the principle of lepton democracy. If they hold up, the standard model will have to be modified—perhaps by the addition of a new charged Higgs boson, whose interactions would depend on mass.
Importantly, this is a combination of several experiments rather than easily attributable to a systematic mistake in one.
- Advanced LIGO turns on after completing upgrade. From now on, LIGO will be able to notify any number of 75 astronomical observatories around the world who have agreed to, at a moment’s notice, point their telescopes to the sky in search of light signals corresponding to possible gravitational wave detections.
New data on great filter from density of habitable planets.
these new results offer little support for the scenario where we have a good chance of growing out into the universe and meeting other aliens before a billion of years have passed. Either we are very likely to die and not grow, or we are the only ones who could grow…The simplest story seems right: if we have a chance to fill the universe, we are the only ones for a billion light years with that chance.
- List of selfie-related injuries and deaths.
- Surprising to me: forests with no net growth are not carbon neutral.
- ISS virtual tour.
- Indirect evidence of cosmic (aka relic) neutrino background in CMB. (PRL.)
A phenomenal and extensive collection of high-speed video of pool shots. I thought I knew a lot of the physics that went into pool, but I did not realize how much depth there is. For example:
- “How Google’s new Logo is just 305 bytes“. Relatedly, Bézier curves are simpler and more sensible than I guessed.
- Robin Hanson comments on metabolism scaling.
- Eye opening anecdotes from academic publishing. The author’s proposed solutions are hilariosly bad.
- Not enough people are aware that breaking RSA-like encryption, the go-to motivation for quantum computers, really isn’t a big deal; everyone will just move to quantum-secure protocols with only a modest speed penalty. Lattice-based methods are a leading contender for a replacement.
- EA primer in the Washington Post.
Maybe bad new for the adoption of open-access:
Scientists’ concerns about open-access (OA) publishing might be fading, according to the results of a large Nature Publishing Group survey released on 13 August (see go.nature.com/t2cxrq). The poll found that more than one-third of scientists have not published any OA papers in the past three years, a proportion that has shifted little since 2014. But last year, 40% of those researchers expressed concerns about perceptions of the quality of OA publications; this year, that proportion dropped to 27%.
Maybe good news: There is a new arXiv overlay journal, Discrete Analysis, with Fields medalist Timothy Gowers as managing editor and Terrance Tao as an editor.
(H/t Ivar Martin. Nature News coverage.)
In my opinion, the best thing about overlay journals is that they remove the disincentive for authors to release their work under copyleft (e.g., creative commons). (I also wonder if a rise in overlay journals would prompt university departments to very sensibly hire copyeditors to free up the time of their professors, but I’m not holding my breath…)
- Missing link.
The Sun is roughly typical star and emits about photon per second in the visible range. It takes about 100 photon incident on the pupil, of which only about 10 are absorbed by a rod cell, to lead to visual perception of a flash by humans. If we require those photons to hit our square-centimeter pupil in a tenth of a second, that means the dimmest stars would be visible from away. And indeed, almost all of the stars we see are within a 1,000-lightyear sphere around the sun, with the very furthest individually visible stars (much brighter than the sun) being 16,000 lightyears away. In comparison, the Milky Way disk is about 1,000 lightyears thick and 100,000 lightyears across, which is why it appears as a dim smear across the night sky with no individually distinguishable stars.
An advance in cache coherence for multi-core processors.
MIT researchers unveil the first fundamentally new approach to cache coherence in more than three decades. Whereas with existing techniques, the directory’s memory allotment increases in direct proportion to the number of cores, with the new approach, it increases according to the logarithm of the number of cores.
There is a spectrum among people interested in research careers, where on one extreme are people who just want to be researchers (in the sense that they enjoy the job, the benefits, etc.) and on the other are those platonic saints who are motivated purely to do the most important research for the good of society. Most people, obviously, fall somewhere in between. Many people would agree that, insofar as the academic job process selects for research output metric that don’t track research value ideally, we will tend to select more for people who want to be researchers rather than those who want to do research. But it’s my opinion that things are worse than this. The academic system doesn’t just make it hard for the idealized researchers to survive, it actively pushes them along the spectrum. The fraction of people who enter grad school saying they want to win nobel prizes, but then slowly morph into boring-paper factories, is too high to attribute to the natural trend of people getting boring as they get older.
Harold Lee sees this happening in lots of places, and (very speculatively) speculates that it has to do with most of the prestigious career paths involving no positions of command, in contrast to the many military careers of the past. I don’t know exactly what economic considerations prevent grad student for having more subordinate undergrads, or young lawyers ordering around more interns. However, I do think this story is consistent with the impressive ambition of folks coming out of the few industries where smart young people can quickly become commanders: technology start-ups.
- New article on Europa in Nautilus.
- Terraforming Mars by nudging asteroids into a collision course? Apprently, forty such impacts would give Mars a temperate climate, and enough water would have been melted to cover a quarter of the planet with a layer of water 1 m deep. (PDF. Free HTML.)
- Description of a sunspot.
Hands down the best pictures yet from New Horizons, one of my favorite astronomical images of all time. Here’s a direct link to the raw B&W but I am perfectly happy to indulge in colorization:
The fact that you can see surface height features in 3D in the same image as you see the curvature of Pluto is incredible. I dare you to not click that image and zoom in.
- Incidentally, I hadn’t seen this shot of Europa passing in front of Jupiter’s great red spot before. Great resolution and artificially colorized:
- “These 25 schools are responsible for the greatest advances in science.” Princeton lagging behind some other elite colleges according to some metrics of accomplishment for its alumni. Commentary/summary by Steve Hsu.
- Informative YouTube channels. (HN discussion.)
- Some recent developments in indistinguishability obfuscation and functional encryption. (HN discussion. Related Stack Exchange discussion.)
- Hiccups during Apollo 12, along with actual audio conversation between mission control and the astronauts.
- Nasa study subjects healthy guy to 70 days of bedrest.
- The talks from EA Global are now online.
- Project Oilsand (H/t Scott Alexander.)
- Also from Scott: “Harvard University says it can’t afford journal publishers’ prices“. Lol. In any case, hopefully this pushes toward open access (and therefore forkable papers!) To solve this collective action problem, I recommend going to the bottleneck with the fewest actors and least reason to defect: funders. All academic funders should make publishing open access a condition of receiving grants. This aligns well with the goals of funders (produce and spread knowledge) and needn’t involve coercion (you don’t have to take the money). And it’s working in the form of mandates like the NIH’s.
Some support for the hypothesis that males have greater variability than females (PDF):
Greater Intrasex Phenotype Variability in Males Than in Females is a Fundamental Aspect of the Gender Differences in Humans
Human studies of intrasex variability have shown that males are intellectually more variable. Here we have performed retrospective statistical analysis of human intrasex variability in several different properties and performances that are unrelated or indirectly related to intelligence: (a) birth weights of nearly 48,000 babies (Medical Birth Registry of Norway); (b) adult weight, height, body mass index and blood parameters of more than 2,700 adults aged 18–90 (NORIP); (c) physical performance in the 60 meter dash event of 575 junior high school students; and (d) psychological performance reflected by the results of more than 222,000 undergraduate university examination grades (LIST). For all characteristics, the data were analyzed using cumulative distribution functions and the resultant intrasex variability for males was compared with that for females. The principal finding is that human intrasex variability is significantly higher in males, and consequently constitutes a fundamental sex difference.
A related comment by David Friedman points out that fact that the mean score on IQ-loaded tests is the same for men and women is not really a gauge-invariant fact. Women do consistently better than men on some question, and vice versa, so the relative means can be shifted by choosing how many questions of each type to have.
- MRIs of fruit. Yep.
- More Scott: Psychologists distort statistics, but journalists are way worse. This is one of my least favorite practices, and it’s rampant.
- I always assumed that the “US vs. International” dichotomy among possible index funds was only a natural sort of split for US citizens who felt more comfortable investing in their own stocks, but it turns out that this split actually divides the world fairly evenly.
World record solving Rubik’s cube with feet:
- New idea for reducing carbon emissions: allow for permanent carbon easements so that philanthropic foundations can purchase mineral rights to coal deposits and ensure that the carbon is never burned. Has some interesting economic properties, although I wonder if these lead to weird incentives to find new coal and sell it even though it never would have been extracted in the first place. Probably not an issue so long as coal extraction cost estimates are reasonably reliable.
- Carl Shulman: “There is a prize for good national leaders in Africa who voluntarily give up power at the end of their democratically elected terms (so far awarded in 4 out of 8 years).” The Ibrahim Prize.
- US presidental candidate betting odds. Sadly must be based on UK betting data, since these have been outlawed in the states.
LaTeX in commentsInclude [latexpage] to render LaTeX in comments. (More.)
- Legendre transform (4)
- Branches and matrix-product states (6)
- Jess Riedel This prompted me to take an old email where I listed some models of branching... – Oct 12, 3:16 AM
- interstice Thanks. Do you know of any systems, toy or real, where we can identify a... – Oct 11, 10:06 PM
- Jess Riedel Great question. It is not obvious that we should define branches from the tensor structure... – Oct 10, 8:00 PM
- interstice Right, so to argue that the branches evolve independently, one must first define what branches... – Oct 10, 4:19 PM
- Jess Riedel You're right that the criteria for defining branches I give in the paper doesn't make... – Oct 05, 2:33 PM
- interstice I have a stupid(?) question. The criteria you give in the paper doesn't involve time-evolution... – Oct 05, 12:36 PM
- Comments on Weingarten's preferred branch (1)
- Links for August-September 2017 (2)
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