Tuesday, July 28, 2009

Whale Sharks

I went swimming with whale sharks near Cancun, Mexico with Manuel Lazcano. We saw over a hundred whale sharks feeding together right on the surface. The hydrodynamics of swimming with the whale sharks was quite interesting. It was almost effortless to stay next to the whale sharks when swimming in a certain spot, over the pectorial fin. Otherwise, they were travelling fast enough that it required a lot of work to keep up.
Alas neither of the photos below (by Carlos Requena) show me in the "sweet spot".

Wednesday, July 22, 2009

More Completely Over the Top Music Videos

Pink: Just Like a Pill

Black Eyed Peas - Pump It

Eminem - The Real Slim Shady

Eminem-Without Me

Foo Fighters - Everlong

Fiona Apple - Criminal

David Bowie - Ashes To Ashes

The Killers - Mr. Brightside

OutKast - Hey Ya!

OK Go - Here It Goes Again

Verka Serduchka

The Queen of Over the Top Music Videos is the Ukranian phenom Verka Serduchka. Here are some of my favorites:

The GSI Anomaly

The GSI anomaly
Recently, an experiment at GSI Darmstadt has observed oscillating decay rates of heavy ions. Several controversial attempts have been made to explain this effect in terms of neutrino mixing. We briefly describe the experimental results, give an overview of the literature, and show that the effect cannot be due to neutrino mixing. If the effect survives, it could, however, be explained by hypothetical internal excitations of the mother ions (~ 10^(-15) eV).

Why a splitting in the final state cannot explain the GSI-Oscillations
In this paper, I give a pedagogical discussion of the GSI anomaly. Using two different formulations, namely the intuitive Quantum Field Theory language of the second quantized picture as well as the language of amplitudes, I clear up the analogies and differences between the GSI anomaly and other processes (the Double Slit experiment using photons, $e^+ e^- \to \mu^+ \mu^-$ scattering, and charged pion decay). In both formulations, the conclusion is reached that the decay rate measured at GSI cannot oscillate if only Standard Model physics is involved and the initial hydrogen-like ion is no coherent superposition of more than one state (in case there is no new, yet unknown, mechanism at work). Furthermore, a discussion of the Quantum Beat phenomenon will be given, which is often assumed to be able to cause the observed oscillations. This is, however, not possible for a splitting in the final state only.

Do Electrons Oscillate?

Neutrino Oscillation is the theorectical explanation of the Solar Neutrino Problem. All attempts to measure the elusive neutrinos which should theorectically be produced by nuclear fusion in the sun came up short by a factor of three. The explanation is that neutrinos come in three flavors and they oscillate amongst the flavors while they travel.
The three flavors of neutrino correspond to the three flavors of electron, which include the muon and the tau - heavier, unstable particles otherwise very similar to the electron. So then shouldn't the different flavors of electron oscillate just like the neutrino flavors? The answer is they do, but it doesn't come up much in practice - see the post by Carlb in physics forums. Here's a previous blog post on the same topic: lepton oscillation.

Monday, July 20, 2009

The Golden Ass

I just finished reading the Golden Ass of Lucius Apuleius - originally in Latin from the second century - on the Kindle in a sixteenth century translation, which I downloaded free from Project Gutenberg. It was a bawdy and entertaining tale.
The witch Meroe in the story is a lamia.

Color Glass Condensate

A Brief Introduction to the Color Glass Condensate and the Glasma: exotic forms of matter may arise in high energy collisions.

Sunday, July 19, 2009

Quark Mixing

This preprint Quark Mixing and CP Violation gives a decent exposition of the CKM quark mixing matrix, weak interaction eigenstates, mass eigenstates and all that.
The preprint Three Lectures on Meson Mixing and CKM phenomenology points out that certain neutral mesons (including the neutral K meson) mix with their antiparticles. This was a big surprise to me. It's odd enough that particle/antiparticle states don't usually mix, but there are exceptions to that rule too!
Note that many neutral antiparticles don't mix because of other conservation laws, neutrons and neutrinos obey baryon and lepton number conservation, or so it seems.
See also Status of CP Violation for another fairly recent review.

Here's another very recent preprint: Flavor Questions for the LHC
The physics underlying quark and lepton masses and mixings (the "flavor problem") is the least well understood aspect of the Standard Model. Some questions of flavor physics, and ways in which the LHC can help shed light on this problem, are described.

Flavor Physics in the Quark Sector is another recent summary of quark mixing and CP Violation experiments and theory.

Saturday, July 18, 2009

Topological Insulators

Edge-State Physics Without Magnetic Fields in Science.
Solids can be divided into conductors and insulators. A new class of materials, called topological insulators, has been predicted (1, 2) that exhibit surface states that lead to quantized conductance of charge and spin. These surface states are helical edge states, which interconnect spin and momentum of the carriers. Observation of these states should not require application of a magnetic field.

Here's a potential application: Topological Quantum Image Analysis physics preprint.
A new approach to analyzing visual images is proposed, based on the idea of converting an optical image into a spatially varying pattern of polarized squeezed light, which is then used to produce a pattern of chiral edge currents in a thin film topological insulator. Thin films of Bi or Bi doped with Sb which are punctured with an array of sub-micron holes may be a way of realizing this kind of optical quantum information processing.

For a good introduction see A New Spin on the Insulating State in Science.

A Deeper Quantum Theory?

Is Quantum Theory Exact? by Stephen L. Adler and Angelo Bassi.
According to the standard theory, the state of a quantum system evolves deterministically according to Schrödinger's equation until the state is measured, when there's an apparently instantaneous nondeterministic transition to a new state.
How can we reconcile this probabilistic distribution of outcomes with the deterministic form of Schrödinger's equation? What precisely constitutes a "measurement?" At what point do superpositions break down, and definite outcomes appear? Is there a quantitative criterion, such as size of the measuring apparatus, governing the transition from coherent superpositions to definite outcomes? These puzzles have inspired a large literature in physics and philosophy.

The article asks whether there might be a deeper-level theory which explains quantum weirdness.
See also their preprint Collapse models with non-white noises.

Cats Modify Purring to Manipulate their Owners

Cat Purrs Evoke Baby Cries
There may be more to a cat's purr than meets the ear. A new study reports that our feline friends modify their signature sound when seeking food, adding a higher-frequency element that exploits our sensitivity to infant wails--and thus making it harder to ignore.

Elegant Microfluidic Images

This article contains more nice photomicrographs of emulsions High-Order Multiple Emulsions Formed in Poly(dimethylsiloxane) Microfluidics.

Climate Flip-Flops

What Drives Climate Flip-Flops?
Around 14,600 years ago, the atmospheric circulation over the North Atlantic region flipped within just a few years to another state (2); also, Greenland temperatures skyrocketed by >10°C over several decades (3), terminating a cold phase known as Heinrich Event 1. The global impacts of this Bølling-Allerød transition have been well documented with climate proxy records such as sediment cores and ice cores, but the physical conditions that triggered the transition remain controversial. The temperature evolution from the Heinrich Event 1 to the Bølling-Allerød and the subsequent Younger Dryas cold phase (see the figure) is strikingly similar to the Dansgaard-Oeschger cycles (4) that dominated Northern Hemispheric climate between 60,000 and 30,000 years ago (5). Hence, unraveling the processes that triggered the Bølling-Allerød transition may also help to elucidate the mysterious, tantalizingly regular Dansgaard-Oeschger cycles (6).

Giant Planets on the Move!

Shifting Orbits Gave Solar System A Big Shakeup, Model Suggests
Planetary scientists are finding that the four outermost planets of our solar system haven't always been orbiting where they are today. They've moved, some a considerable distance outward. The most catastrophic scenario for such planet migration, dubbed the Nice model (after the French city), has been gaining ground of late. It envisions the great reshuffling as a brief, violent affair that not only put the outer planets where they are today but also created the Kuiper belt of small icy bodies beyond Neptune, gave the planets scores of oddly orbiting moons, and bombarded the solar system with a rain of asteroids and comets so fierce that it would have cooked all but the deepest subterranean life on early Earth. The latest support for the Nice model, a new explanation for primitive-looking asteroids, appears this week in Nature. But the model has more hurdles to clear, such as explaining why the innermost planets—Earth and its neighbors—weren't reshuffled as well.

Mysterious Ancient Global Warming

Ancient Climate-Change Event Puzzles Scientists
Over the past couple of decades, researchers have been gathering data about a mysterious event known as the Paleocene-Eocene Thermal Maximum (PETM). The data, derived from drill cores brought up from the deep seabed in the Atlantic and Pacific Oceans, show that the surface temperature of the planet rose by as much as 9°C within 10,000 years during the PETM, which itself started out warmer than our current world. Temperatures stayed at this elevated level for nearly 100,000 years.

Friday, July 17, 2009

Steven Weinberg on Quantum Field Theory - Video

The Quantum Theory of Fields: Effective or Fundamental? talk by Steven Weinberg at CERN, July, 2009.

Statistics and Causality

Traditionally, Statistics has been concerned with uncovering and describing associations, and statisticians have been wary of causal interpretations of their findings. But users of Statistics have rarely had such qualms. For otherwise what is it all for?
The enterprise of “Statistical Causality” has developed to take such concerns seriously. It has led to the introduction of a variety of formal methods for framing and understanding causal questions, and specific techniques for collecting and analysing data to shed light on these.

One of the examples mentioned is the quite simple but highly unintuitive Simpson's Paradox. The Berkeley sex bias case is particularly bizarre.

Thursday, July 16, 2009

Feynman Videos Online at Microsoft

Videos of a series of lectures from 1964 by Physics Nobel Prize winner Richard Feynman has been placed on the web at Microsoft.
"This law has been called the greatest generalization achieved by the human mind. And you can get already from my introduction, that I'm interested not so much in the human mind as in the marvel of nature, who can obey such an elegant and simple law as this law of gravitation. So our main concentration will not be on how clever we are to have found it all out, but on how clever she is to pay attention to it."

Primordial Lithium Problem

A Bitter Pill: The Primordial Lithium Problem Worsens
The lithium problem arises from the significant discrepancy between the primordial 7Li abundance as predicted by BBN theory and the WMAP baryon density, and the pre-Galactic lithium abundance inferred from observations of metal-poor (Population II) stars. This problem has loomed for the past decade, with a persistent discrepancy of a factor of 2--3 in 7Li/H.

Effect of quark-mass variation on big bang nucleosynthesis
Measurements of the primordial baryon-to-photon ratio
η from the cosmic microwave background from
WMAP [1], coupled with precise measurements of the
neutron half-life [2], have made big bang nucleosynthesis
(BBN) an essentially parameter-free theory [2, 3, 4]. In
this paradigm excellent agreement has been obtained between
predicted and observed abundances of deuterium
and 4He (see, e.g. the Particle Data Group review [2] and
references therin). However there is some disagreement
for 7Li, the only other element for which the abundance
has been measured to an accuracy at which fruitful comparison
with theory can be made. While the “lithium
problem” has been known for some time, it has been exacerbated
by recent measurements of the 3He(α, γ)7Be
reaction [5]. Standard BBN theory with η provided
by WMAP 5 overproduces 7Li by a factor of 2.4 – 4.3
(around 4 – 5σ) [4].

Solar System Anomalies

There are at least four unexplained anomalies connected with astrometric data. Perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. Next, a secular change in the astronomical unit AU is definitely a concern. It is increasing by about 15 cm yr$^{-1}$. The other two anomalies are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions. Some astronomers and physicists are convinced this effect is of concern, but many others are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth anomaly is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction in both the Earth and Moon. However, there is a reported unexplained increase that is significant at the three-sigma level. It is prudent to suspect that all four anomalies have mundane explanations, or that one or more anomalies are a result of systematic error. Yet they might eventually be explained by new physics. For example, a slightly modified theory of gravitation is not ruled out, perhaps analogous to Einstein's 1916 explanation for the excess precession of Mercury's perihelion.

Wednesday, July 15, 2009

Space-Time Sensors using Atomic Levitation

Space-Time Sensors using Multiple-Wave Atomic Levitation
Optical atomic clocks are promising tools to investigate basics physics through fundamental tests. The best clocks to date control the atomic motion by trapping the sample in an optical lattice and then interrogate the atomic transition by shining on these atoms a distinct laser of controlled frequency. In order to perform both operations simultaneously and with the same laser field, we propose to use instead the levitation of a Bose-Einstein condensate through multiple-wave atomic interferences. The levitating condensate experiences a coherent localization in momentum and a controlled diffusion in altitude. The sample levitation is bound to a set of resonance conditions used either for frequency or for acceleration measurements. The chosen vertical geometry solves the limitations imposed by the sample free fall in previous optical clocks using also atomic interferences. This configuration allows for multiple-wave interference effects, which maintain the atomic population in levitation and yield a sensitivity improvement. This setup constitutes an attractive alternative to current atomic clocks and gravimeters.

Tuesday, July 14, 2009

Cosmic Microwave Background Anomalies

NASA / WMAP Science Team

Large scale alignment anomalies of CMB anisotropies: a new test for residuals applied to WMAP 5yr maps
The paper lists some anomalies of the CMB with respect to the lambda cold dark matter model:
1. There is low correlation (essentially zero) at large angles, not expected.
2. Unlikely alignments of low order multipole moments: the quadrupole and octupole moments with the dipole moment (which is caused by the motion of the earth). AKA "The Axis of Evil".
3. The two hemispheres defined by the plane of the solar system are asymmetric.
4. A Cold Spot in the southern hemisphere.

Dark Matter Astrophysics

Dark Matter Astrophysics preprint
These lectures are intended to provide a brief pedagogical review of dark matter for the newcomer to the subject. We begin with a discussion of the astrophysical evidence for dark matter. The standard weakly-interacting massive particle (WIMP) scenario--the motivation, particle models, and detection techniques--is then reviewed. We provide a brief sampling of some recent variations to the standard WIMP scenario as well as some alternatives (axions and sterile neutrinos). Exercises are provided for the reader.

Monday, July 13, 2009

Hominin Evolution

Middle and later Pleistocene hominins in Africa and Southwest Asia in PNAS.
Approximately 700,000 years ago, Homo erectus in Africa was giving way to populations with larger brains accompanied by structural adjustments to the vault, cranial base, and face. Such early Middle Pleistocene hominins were not anatomically modern. Their skulls display strong supraorbital tori above projecting faces, flattened frontals, and less parietal expansion than is the case for Homo sapiens. Postcranial remains seem also to have archaic features. Subsequently, some groups evolved advanced skeletal morphology, and by ca. 200,000 years ago, individuals more similar to recent humans are present in the African record. These fossils are associated with Middle Stone Age lithic assemblages and, in some cases, Acheulean tools. Crania from Herto in Ethiopia carry defleshing cutmarks and superficial scoring that may be indicative of mortuary practices. Despite these signs of behavioral innovation, neither the Herto hominins, nor others from Late Pleistocene sites such as Klasies River in southern Africa and Skhūl/Qafzeh in Israel, can be matched in living populations. Skulls are quite robust, and it is only after ≈35,000 years ago that people with more gracile, fully modern morphology make their appearance. Not surprisingly, many questions concerning this evolutionary history have been raised. Attention has centered on systematics of the mid-Pleistocene hominins, their paleobiology, and the timing of dispersals that spread H. sapiens out of Africa and across the Old World. In this report, I discuss structural changes characterizing the skulls from different time periods, possible regional differences in morphology, and the bearing of this evidence on recognizing distinct species.

An ancient human skull (pictured above) was found in Israel at Skhūl cave!?

Genetic Analysis of Copernicus?

It's impressive that they can now do so much with remains that are over 400 years old. Genetic identification of putative remains of the famous astronomer Nicolaus Copernicus at PNAS.
We report the results of mitochondrial and nuclear DNA analyses of skeletal remains exhumed in 2005 at Frombork Cathedral in Poland, that are thought to be those of Nicolaus Copernicus (1473–1543). The analyzed bone remains were found close to the altar Nicolaus Copernicus was responsible for during his tenure as priest. The mitochondrial DNA (mtDNA) profiles from 3 upper molars and the femurs were identical, suggesting that the remains originate from the same individual. Identical mtDNA profiles were also determined in 2 hairs discovered in a calendar now exhibited at Museum Gustavianum in Uppsala, Sweden. This calendar was the property of Nicolaus Copernicus for much of his life. These findings, together with anthropological data, support the identification of the human remains found in Frombork Cathedral as those of Nicolaus Copernicus. Up-to-now the particular mtDNA haplotype has been observed only 3 times in Germany and once in Denmark. Moreover, Y-chromosomal and autosomal short tandem repeat markers were analyzed in one of the tooth samples, that was much better preserved than other parts of the skeleton. Molecular sex determination revealed that the skeleton is from a male individual, and this result is consistent with morphological investigations. The minimal Y-chromosomal haplotype determined in the putative remains of Nicolaus Copernicus has been observed previously in many countries, including Austria, Germany, Poland, and the Czech Republic. Finally, an analysis of the SNP located in the HERC2 gene revealed the C/C genotype that is predominant in blue-eyed humans, suggesting that Copernicus may have had a light iris color.

See this blog post for more information about the HERC2 gene HERC2 & blue eye color & Danes

B Factories

Future prospects of B physics
In recent years, the CKM picture of flavor and CP violation has been confirmed, mainly due to B decay data. Yet, it is likely that there are small corrections to this picture. We expect to find new physics not much above the weak scale. This new physics could modify flavor changing processes compared to their SM expectations. Much larger B decay data sets, which are expected from LHCb and super-B-factories, will be used to search for these deviations with much improved sensitivity. The combination of low and high energy data will be particularly useful to probe the structure of new physics.

LHCb detector

Hierarchy problems

In particle physics, the Hierarchy problem is the question why the weak force is 10^32 times stronger than gravity. The Cosmological constant problem is that most quantum field theories predict a huge cosmological constant from the energy of the quantum vacuum . The value is off by 120 orders of magnitude, which is said to be the worst prediction in theorectical physics! In the preprint The Concept of a Cosmographical Vacuum we have:
The argument for a novel concept with a not unique, ``Cosmographical Vacuum'' state which generates fermion and weak boson masses is outlined in a brief and concise way.

The following preprint discusses the particle physics hierarchy problem and the problem of the very small but nonzero neutrino masses using the (speculative) possibility of extra dimensions:
Signatures of Singlet Neutrinos in Large Extra Dimensions at the LHC
It is a challenge to explain why neutrinos are so light compared to other leptons. Small neutrino masses can be explained if right-handed fermions propagate in large extra dimensions. Fermions propagating in the bulk would have implications on Higgs boson decays. If the Higgs boson is discovered at the Large Hadron Collider (LHC), a detailed analysis may reveal the presence of large extra dimensions. This paper reviews the status of large extra-dimensional models in the context of the current limits on Higgs boson masses and the fundamental Planck scale in extra dimensions.

Solar Circulation Paradox

Secrets of Magnetohydrodynamic Hell: The Solar Circulation Paradox and the Geodynamo
Differential rotation is widely supposed to be essential for the dynamo effects that sustain solar and planetary magnetic fields, but dynamo effects tend to oppose the flows that drive them, and it is uncertain what drives differential rotation. The relative sign of the differential rotation and meridional circulation is not consistent with simple convection modified by Coriolis forces. We investigate dynamo mechanisms consistent with the observed solar circulation, and discuss how reactive JxB forces would affect such flows. We formulate scaling rules that relate the magnetic field strength to mean rotation and convective heat transport.

On Time Reversal Mirrors

Narcissus by Caravaggio
A friend of mine complained that her boyfriend accused her of never passing a mirror without checking herself out, and that she spent half her life looking at her face in the mirror. Well if that were true and my friend had herself a Time Reversal Mirror, she would never get older! Sorry, that application is not actually discussed in this preprint, despite the promising title: On time reversal mirrors.
Time reversal (TR) is the process of recording the signal, time-reversing and re-propagating the signal. When the signal is from a localized source the time reversed field is expected to focus on the source. Time reversal of acoustic waves has led to applications in ultrasound and underwater acoustics including brain therapy, lithotripsy, nondestructive testing and telecommunications [17]. An even greater potential holds for the time reversal of electro-magnetic waves which is closely related to optical phase conjugation [28].

While it isn't quite the fountain of youth for the narcissists among us, there are exciting applications.

Dorian Gray used a different technology to remain youthful.

The Space Station

Space Station Is Near Completion, Maybe the End Plan to 'De-Orbit' in 2016 Is Criticized - article in the Washington Post. After $100 billion dollars the space station should be completed next year. Then we're going to burn it up over the ocean in 2016. Nice. Essentially no science has ever been done on the space station, though there's supposed to be an experiment brought up on the last shuttle flight in 2010. After that the space station can only be reached by the Russian Soyuz. What a waste. Someone in the article suggested that instead of destroying it we should give it to China!
Photo NASA

Sunday, July 12, 2009

Vanity Fair on Finance and Politics

It Came from Wasilla

The August 2009 issue of Vanity Fair magazine had several interesting articles: It Came From Wasilla a hatchet job about Sarah Palin; The Man Who Crashed the World on the collapse of financial giant AIG by Michael Lewis; RICH HARVARD, POOR HARVARD "If Harvard is so smart, how come its record $36.9 billion endowment has collapsed" about the financial problems of my neighbor here in Cambridge; and a strangely sweet story about paparazzi Michael Jackson’s Last Close-Up. You'll have to buy the magazine to read the article about Harvard, the rest are on the web site.
The Harvard article (p.145) claims that the average full professor at Harvard makes $192,600 not including benefits. I'm surprised that's so high. I had been under the impression that the most prestiguous universities could actually get away with paying their faculty comparatively lower wages because professors were willing to give up salary to work at a big name institution.

Saturday, July 11, 2009


Swoopo is The Crack Cocaine of Auction Sites.

Mantis Shrimps are Really, Really Cute

Photos of mantis shrimps found on the web, for the source and attribution, click on the photo.

An Ancient Explosion of Land Plants?

When Earth greened over: Explosion of animal life could have been triggered by blanket of vegetation.
A thick, green carpet of photosynthetic life, on the scale of that seen today, exploded across Earth 850 million years ago — much earlier than thought — a new study suggests.

Thursday, July 09, 2009

Spontaneous Symmetry Breaking

Steven Weinberg reflects on spontaneous symmetry breaking, and the connection between condensed-matter physics and particle physics

Unanswered Questions in the Electroweak Theory

Unanswered Questions in the Electroweak Theory by Chris Quigg
For all its triumphs, the electroweak theory has many shortcomings. It does not make specific predictions for the masses of the quarks and leptons or for the mixing among different flavors. It leaves unexplained how the Higgs boson mass could remain below 1 TeV in the face of quantum corrections that tend to lift it toward the Planck scale or a unification scale. The Higgs field that must pervade all of space to hide the electroweak symmetry contributes a vacuum energy density far in excess of what is observed. And the electroweak theory responds inadequately to challenges raised by astronomical observations, including the dark-matter problem and the baryon asymmetry of the Universe. These shortcomings argue for physics beyond the standard model; some possibilities are recalled.

Wednesday, July 08, 2009

Kindle Definitions continued

I've been reading Ivanhoe on the Kindle. It was written in 1812 and the story was set long before that. There are many archaic terms used in the book, for example: kirtle, dingle and baldric. I probably wouldn't have bothered looking those up if I was reading the book in print but it was nice and easy on the Kindle. Not that these are likely to come up in conversation, even here in Cambridge.

Classical vs. Quantum Thought?

Classical Logical versus Quantum Conceptual Thought: Examples in Economy, Decision theory and Concept Theory
Inspired by a quantum mechanical formalism to model concepts and their disjunctions and conjunctions, we put forward in this paper a specific hypothesis. Namely that within human thought two superposed layers can be distinguished: (i) a layer guided by an underlying classical deterministic process, giving rise to essentially logical thought and its indeterministic version modeled by classical probability theory; (ii) a layer guided by conceptual weights of different types, such as 'typicality', 'membership', 'representativeness', 'similarity', 'applicability', 'preference' or 'utility', giving rise to what we call 'conceptual thought', indeterministic in essence, but equally well, although very differently, organized than logical thought. A substantial part of the conceptual thought process can be modeled by quantum mechanical probabilistic structures. We consider examples of three specific domains of research where the effects of the presence of conceptual thought and its deviations from classical logical thought have been noticed and studied, i.e. economics, decision theory, and concept theories and which provide experimental evidence for our hypothesis.

Tuesday, July 07, 2009

A Brief History of Planet Earth

The Earth – For Physicists is an article by John Baez with a somewhat unfortunate title. You don't actually need a background in physics to follow this synopsis of the origin and development of our planet.

Definitions in Kindle

Though the Kindle user interface is admittedly rather rudimentary, there's one seemingly minor feature that works great in practice. While reading a document, when you move the cursor onto a word it gives you a one line definition at the bottom of the screen. Hit return and it switches to a screen with the complete definition. I use this feature quite frequently. Even when I'm more or less familiar with a word, it's sometimes nice to check the exact definition. I don't check definitions nearly enough when I read normally, due to laziness, but the Kindle makes it painless enough that I've been actually doing it.

Monday, July 06, 2009

Kindle Shines in the Sun

I recently purchased a Kindle DX from Amazon, mainly hoping to use it while travelling. I've more or less ignored it since the first couple of days after it arrived. But today is a gorgeous sunny day for a change here in Boston, so I decided to try to read something out on my deck, which is blazingly bright today. I brought out the Kindle and was pleasantly surprised by how easy it was to read while wearing a pair of extremely dark polarized sunglasses. I found reading on the Kindle easier on my eyes than a paperback book, perhaps in part because the print is somewhat larger on the Kindle. As a joke, I brought out my laptop. I could barely see anything on the laptop screen in the sunlight without my sunglasses and absolutely nothing with the sunglasses on.
On a nice sunny day I often would like to read outdoors, but usually find the eye strain too much. The Kindle seems to help in this situation.

On the other hand the E Ink display used by the Kindle has its quirks too: there's a dramatic flash when the page is changed and there's long decay time when erasing the cursor, etc. However, I don't really even notice the page change flash anymore, though I certainly did when I first got it.

This Snake is a Fake Out Artist

The Tentacled Snake, an aquatic reptile of southeast Asia, does a nice job of faking out its fish prey: Tentacled snakes turn C-starts to their advantage and predict future prey behavior.

Many People Reject Unfair Offers Even When They Screw Only Themselves

The private rejection of unfair offers and emotional commitment
In a series of experiments, we demonstrate that certain players of an economic game reject unfair offers even when this behavior increases rather than decreases inequity. A substantial proportion (30–40%, compared with 60–70% in the standard ultimatum game) of those who responded rejected unfair offers even when rejection reduced only their own earnings to 0, while not affecting the earnings of the person who proposed the unfair split (in an impunity game). Furthermore, even when the responders were not able to communicate their anger to the proposers by rejecting unfair offers in a private impunity game, a similar rate of rejection was observed. The rejection of unfair offers that increases inequity cannot be explained by the social preference for inequity aversion or reciprocity; however, it does provide support for the model of emotion as a commitment device. In this view, emotions such as anger or moral disgust lead people to disregard the immediate consequences of their behavior, committing them to behave consistently to preserve integrity and maintain a reputation over time as someone who is reliably committed to this behavior.

Giant Kangaroo was probably wiped out by Humans

The largest-ever kangaroo, Procoptodon goliah disappeared about the time that humans arrived in Australia. It appears that was not a coincidence: Extinction implications of a chenopod browse diet for a giant Pleistocene kangaroo.

A Tight Biological Loop

Prochlorococcus, a tiny photosynthesing marine bacteria, is one of the smallest and most abundant forms of life. It needs nitrogen which is often a limiting factor in its growth. Apparently a major source of its nitrogen is nitrate, which is produced by organsims which mainly feed on Prochlorococcus itself: Prochlorococcus: Approved for export!

Sunday, July 05, 2009

The Economics of Piracy

Aaaargh-onomics a blog post in the New York Times by Edward L. Glaeser of Harvard, reviews Peter Leeson’s book “The Invisible Hook: The Hidden Economics of Pirates.”
Mr. Leeson’s book represents a serious attempt to use the tools of economics to make sense of the institutions of piracy. The book is another example of economic imperialism, the use of economics to make sense of real world phenomena that are outside the standard realm of economic science. It addresses an important force that did, and does, impact world trade. But as the skull and crossbones on its spine suggests, the book is also just fun.

Benford, Zipf and Pareto

In this blog post Benford’s law, Zipf’s law, and the Pareto distribution Fields medalist Terence Tao discusses three remarkable real-world statistical patterns: Benford’s law, Zipf’s law, and the Pareto distribution.

Saturday, July 04, 2009

Isn't it Ironic?

How to Think, Say, or Do Precisely the Worst Thing for Any Occasion
In slapstick comedy, the worst thing that could happen usually does: The person with a sore toe manages to stub it, sometimes twice. Such errors also arise in daily life, and research traces the tendency to do precisely the worst thing to ironic processes of mental control. These monitoring processes keep us watchful for errors of thought, speech, and action and enable us to avoid the worst thing in most situations, but they also increase the likelihood of such errors when we attempt to exert control under mental load (stress, time pressure, or distraction). Ironic errors in attention and memory occur with identifiable brain activity and prompt recurrent unwanted thoughts; attraction to forbidden desires; expression of objectionable social prejudices; production of movement errors; and rebounds of negative experiences such as anxiety, pain, and depression. Such ironies can be overcome when effective control strategies are deployed and mental load is minimized.

Hurricane Prediction

There appears to be a connection between Central Pacific Warming events and the severity and pattern of hurricanes in the North Atlantic. Central Pacific Warming events occur around the international dateline and are apparently distinct from Eastern Pacific Warming events - El Nino: Impact of Shifting Patterns of Pacific Ocean Warming on North Atlantic Tropical Cyclones and Predicting El Niño's Impacts.

Wednesday, July 01, 2009

The Russians are going to Phobos

Phobos, one of the moons of Mars, is a strange object. The Russians are launching a sample return mission this year: Russia's Dark Horse Plan to Get to Mars.