Quantum Measurement Processes

The Measurement Process in Local Quantum Theory and the EPR Paradox

We describe in a qualitative way a possible picture of the Measurement Process in Quantum Mechanics, which takes into account: 1. the finite and non zero time duration T of the interaction between the observed system and the *microscopic part* of the measurement apparatus; 2. the finite space size R of that apparatus; 3. the fact that the *macroscopic part* of the measurement apparatus, having the role of amplifying the effect of that interaction to a macroscopic scale, is composed by a very large but finite number N of particles.
The conventional picture of the measurement, as an instantaneous action turning a pure state into a mixture, arises only in the limit where N tends to infinity, T tends to zero, R tends to infinity.
The limit where N tends to infinity has been often discussed as the origin of decoherence. We argue here that, as a consequence of the Principle of Locality, before those three limits are taken, no long range entanglement between the values of observables which are spacelike separated far away can be detected (although entangled states for such observables are well known to exist in local theories, simple examples are given in an Appendix). In order to detect correlations, one of the observers has to wait until he enters the future causal shadow of the region employed by the apparatus of the other. Accordingly, in this picture of the measurement process there would be no Einstein Podolski Rosen Paradox. (Similar views had been proposed already [6], [22]). A careful comparison with the growing experimental results of the recent decades might settle the question

The EPR Paradox is one of the most spectacular and disturbing consequences of Quantum theory and Special Relativity. But maybe if we really pay close attention to the microscopic details of the quantum measurement process, the paradox will disappear. This paper doesn't completely resolve these issues, but it does point out some of the idealizations of standard quantum theory that may be contributing to the EPR paradox.

Quantum Gravity

Quantum Gravity: Motivations and Alternatives

The mutual conceptual incompatibility between GR and QM/QFT is generally seen as the most essential motivation for the development of a theory of Quantum Gravity (QG). It leads to the insight that, if gravity is a fundamental interaction and QM is universally valid, the gravitational field will have to be quantized, not at least because of the inconsistency of semi-classical theories of gravity. If this means to quantize GR, its identification of the gravitational field with the spacetime metric has to be taken into account. And the resulting quantum theory has to be background-independent. This can not be achieved by means of quantum field theoretical procedures. More sophisticated strategies have to be applied. One of the basic requirements for such a quantization strategy is that the resulting quantum theory has GR as a classical limit. - However, should gravity not be a fundamental, but an residual, emergent interaction, it could very well be an intrinsically classical phenomenon. Should QM be nonetheless universally valid, we had to assume a quantum substrate from which gravity would result as an emergent classical phenomenon. And there would be no conflict with the arguments against semi-classical theories, because there would be no gravity at all on the substrate level. The gravitational field would not have any quantum properties, and a quantization of GR would not lead to any fundamental theory. The objective of a theory of 'QG' would instead be the identification of the quantum substrate from which gravity results. - The paper tries to give an overview over the main options for theory construction in the field of QG. Because of the still unclear status of gravity and spacetime, it pleads for the necessity of a plurality of conceptually different approaches to QG.

Horse Dung and Telescopes

I'm reading The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science by Richard Holmes. It's about science and culture in the late eighteenth and early nineteen century - mostly British. I just finished the section about William Herschel, the German/English discoverer of the planet Uranus. He was an innovative telescope maker and he employed horse dung to make the moulds which he used to cast the metal mirrors for his telescopes. The book says that horse dung was used for this purpose until the early twentieth century. Herschel was also a professional musician and that's how he made his living until he became famous for discovering the planet.

Distribution of Stars at the Center of the Galaxy

High angular resolution integral-field spectroscopy of the Galaxy's nuclear cluster: a missing stellar cusp?
The distribution of stars near the center of the galaxy isn't what is expected from a model of a supermassive black hole.

Ward Cunningham Interview

Here's a really nice interview with computer programmer Ward Cunningham the originator of the term "Wiki" as in Wikipedia.

The baryonic Tully-Fisher relation

The baryonic Tully-Fisher relation and its implication for dark matter halos

The baryonic Tully-Fisher relation (BTF) is a fundamental relation between baryonic mass and maximum rotation velocity. It can be used to estimate distances, as well as to constrain the properties of dark matter and its relation with the visible matter. In this paper, we explore if extremely low-mass dwarf galaxies follow the same BTF relation as high-mass galaxies. We quantify the scatter in the BTF relation and use this to constrain the allowed elongations of dark matter halo potentials. We obtained HI synthesis data of 11 dwarf galaxies and derive several independent estimates for the maximum rotation velocity. Constructing a BTF relation using data from the literature for the high-mass end, and galaxies with detected rotation from our sample for the low-mass end results in a BTF with a scatter of 0.33 mag. This scatter constrains the ellipticities of the potentials in the plane of the disks of the galaxies to an upper limit of 0-0.06 indicating that dwarf galaxies are at most only mildly tri-axial. Our results indicate that the BTF relation is a fundamental relation which all rotationally dominated galaxies seem to follow.

Honesty - Will or Grace?

Patterns of neural activity associated with honest and dishonest moral decisions

What makes people behave honestly when confronted with opportunities for dishonest gain? Research on the interplay between controlled and automatic processes in decision making suggests 2 hypotheses: According to the “Will” hypothesis, honesty results from the active resistance of temptation, comparable to the controlled cognitive processes that enable the delay of reward. According to the “Grace” hypothesis, honesty results from the absence of temptation, consistent with research emphasizing the determination of behavior by the presence or absence of automatic processes. To test these hypotheses, we examined neural activity in individuals confronted with opportunities for dishonest gain. Subjects undergoing functional magnetic resonance imaging (fMRI) gained money by accurately predicting the outcomes of computerized coin-flips. In some trials, subjects recorded their predictions in advance. In other trials, subjects were rewarded based on self-reported accuracy, allowing them to gain money dishonestly by lying about the accuracy of their predictions. Many subjects behaved dishonestly, as indicated by improbable levels of “accuracy.” Our findings support the Grace hypothesis. Individuals who behaved honestly exhibited no additional control-related activity (or other kind of activity) when choosing to behave honestly, as compared with a control condition in which there was no opportunity for dishonest gain. In contrast, individuals who behaved dishonestly exhibited increased activity in control-related regions of prefrontal cortex, both when choosing to behave dishonestly and on occasions when they refrained from dishonesty. Levels of activity in these regions correlated with the frequency of dishonesty in individuals.

Some people were always honest and they showed no special brain activity, other people were sometimes dishonest and they did display increased brain activity. This doesn't really seem surprising. Which isn't to say that this experiment is trivial, far from it - it's fascinating. It would be interesting to see if there are unusual people who can perform dishonestly without registering any special brain activity. Presumably these people would be naturally good spys, poker players, etc.
See the web page of the Moral Cognition Lab at Harvard.
There's a discussion of the paper at this blog post: Angels and Demons.

Statistics - Levy Laws and 1/f noise

A unified and universal explanation for Lévy laws and 1/f noises

Lévy laws and 1/f noises are shown to emerge uniquely and universally from a general model of systems which superimpose the transmissions of many independent stochastic signals. The signals are considered to follow, statistically, a common—yet arbitrary—generic signal pattern which may be either stationary or dissipative. Each signal is considered to have its own random transmission amplitude and frequency. We characterize the amplitude-frequency randomizations which render the system output's stationary law and power-spectrum universal—i.e., independent of the underlying generic signal pattern. The classes of universal stationary laws and power spectra are shown to coincide, respectively, with the classes of Lévy laws and 1/f noises—thus providing a unified and universal explanation for the ubiquity of these classes of “anomalous statistics” in various fields of science and engineering.

Cosmic Impact at the Younger Dryas Boundary

Shock-synthesized hexagonal diamonds in Younger Dryas boundary sediments

The long-standing controversy regarding the late Pleistocene megafaunal extinctions in North America has been invigorated by a hypothesis implicating a cosmic impact at the Ållerød-Younger Dryas boundary or YDB (≈12,900 ± 100 cal BP or 10,900 ± 100 14C years). Abrupt ecosystem disruption caused by this event may have triggered the megafaunal extinctions, along with reductions in other animal populations, including humans. The hypothesis remains controversial due to absence of shocked minerals, tektites, and impact craters. Here, we report the presence of shock-synthesized hexagonal nanodiamonds (lonsdaleite) in YDB sediments dating to ≈12,950 ± 50 cal BP at Arlington Canyon, Santa Rosa Island, California. Lonsdaleite is known on Earth only in meteorites and impact craters, and its presence strongly supports a cosmic impact event ...

Helitrons

Structure-based discovery and description of plant and animal Helitrons

Helitrons are recently discovered eukaryotic transposons that are predicted to amplify by a rolling-circle mechanism. They are present in most plant and animal species investigated, but were previously overlooked partly because they lack terminal repeats and do not create target site duplications.

Plant genomes: Massive changes of the maize genome are caused by Helitrons

Helitrons are eukaryotic transposable elements recognized only recently by computer analysis of repetitive DNA sequences of Arabidopsis, rice and Caenorhabditis elegans (Kapitonov and Jurka, 2001). Helitrons are quite large (>10 kbp) but unlike virtually all other classes of transposable elements, Helitrons lack terminal repeats and do not duplicate host sequences during the insertion process. They insert within the host dinucleotide, AT.

Living Fossils?

Nine exceptional radiations plus high turnover explain species diversity in jawed vertebrates

The other main deviations from our constant-rate model are the prototypical ‘‘living fossil’’ lineages, old lineages with few extant species (17, 18). In our study, 3 living fossil lineages are notable for both their low rate of speciation and extremely low rates of extinction. These groups stand out in stark contrast to the rest of the vertebrate tree, which is characterized by high rates of both speciation and extinction (Fig. 2). This highlights one of the key challenges presented by living fossils to molecular based studies of extant diversity: although young species-rich groups can be explained by a transient increase in net diversification rates for a relatively short period, older species-poor groups require negligible rates of both speciation and extinction over tremendously long periods of time to explain their persistence. We note that all 3 slowly evolving lineages were historically more diverse than they are today.

Why are these groups called "living fossils"? They diverged a long time ago and they have few surviving species. Why does that lead anyone to believe that the modern organisms are similiar to ancient ones?

Sirtuins - enzymes which regulate lifespan?

Recent progress in the biology and physiology of sirtuins

The sirtuins are a highly conserved family of NAD+-dependent enzymes that regulate lifespan in lower organisms. Recently, the mammalian sirtuins have been connected to an ever widening circle of activities that encompass cellular stress resistance, genomic stability, tumorigenesis and energy metabolism. Here we review the recent progress in sirtuin biology, the role these proteins have in various age-related diseases and the tantalizing notion that the activity of this family of enzymes somehow regulates how long we live.

Electricity from Kites

Wind power: High hopes in Nature.

A vast supply of energy is racing around the planet far above the surface. Erik Vance meets the engineers trying to bring the power of high-altitude wind down to earth.

Helical Dirac fermions

A tunable topological insulator in the spin helical Dirac transport regime

Helical Dirac fermions—charge carriers that behave as massless relativistic particles with an intrinsic angular momentum (spin) locked to its translational momentum—are proposed to be the key to realizing fundamentally new phenomena in condensed matter physics

First observation of spin-helical Dirac fermions and topological phases in undoped and doped Bi2Te3 demonstrated by spin-ARPES spectroscopy

Electron systems that possess light-like dispersion relations or the conical Dirac spectrum, such as graphene and bismuth, have recently been shown to harbor unusual collective states in high magnetic fields. Such states are possible because their light-like electrons come in spin pairs that are chiral,which means that their direction of propagation is tied to a quantity called pseudospin that describes their location in the crystal lattice. An emerging direction in quantum materials research is the manipulation of atomic spin-orbit coupling to simulate the effect of a spin dependent magnetic field,in attempt to realize novel spin phases of matter. This effect has been proposed to realize systems consisting of unpaired Dirac cones that are helical, meaning their direction of propagation is tied to the electron spin itself, which are forbidden to exist in graphene or bismuth.

X Rays from Nanotubes

Nanotubes sharpen X-ray vision

Mini X-ray tubes could revolutionize radiotherapy — and airport baggage scanners.

Is the Toucan's Bill primarily a Heat Exchanger?

Heat Exchange from the Toucan Bill Reveals a Controllable Vascular Thermal Radiator

The toco toucan (Ramphastos toco), the largest member of the toucan family, possesses the largest beak relative to body size of all birds. This exaggerated feature has received various interpretations, from serving as a sexual ornament to being a refined adaptation for feeding. However, it is also a significant surface area for heat exchange. Here we show the remarkable capacity of the toco toucan to regulate heat distribution by modifying blood flow, using the bill as a transient thermal radiator. Our results indicate that the toucan's bill is, relative to its size, one of the largest thermal windows in the animal kingdom, rivaling elephants’ ears in its ability to radiate body heat.

Polarized Signalling in Animals

Many animals create striking visual effects not with pigments but with intricately structured materials. See how some scarab beetles produce their colorful appearence in Evolutionary Photonics with a Twist.

Pathological Science

Pathological Science is when investigators trick themselves into believing false results. There was a classic talk PATHOLOGICAL SCIENCE given by Irving Langmuir in 1953.

Did the Immune System Originate with a Virus?

The immune system has the incredible ability to create a vast number of very specific antibodies. In Immune System: Success Owed to a Virus? the author conjectures that the recombination process which generates so much variety may have originated with a virus.

Rare Venomous Mammal

The Solenodon is a very rare and strange little mammal, it is the only mammal that injects venom through its teeth like snakes. See Saving a Venomous Ghost in Science. The are kind of cute too, see Venomous mammal caught on camera.

Phonon Lasers

Phonon laser action in a tunable, two-level photonic molecule

The phonon analog of an optical laser has long been a subject of interest. We demonstrate a compound microcavity system, coupled to a radio-frequency mechanical mode, that operates in close analogy to a two-level laser system. An inversion produces gain, causing phonon laser action above a pump power threshold of around 50 $\mu$W. The device features a continuously tunable, gain spectrum to selectively amplify mechanical modes from radio frequency to microwave rates. Viewed as a Brillouin process, the system accesses a regime in which the phonon plays what has traditionally been the role of the Stokes wave. For this reason, it should also be possible to controllably switch between phonon and photon laser regimes. Cooling of the mechanical mode is also possible.

Nuclear Astrophysics

Massive stars as thermonuclear reactors and their explosions following core collapse

Nuclear reactions transform atomic nuclei inside stars. This is the process of stellar nucleosynthesis. The basic concepts of determining nuclear reaction rates inside stars are reviewed. How stars manage to burn their fuel so slowly most of the time are also considered. Stellar thermonuclear reactions involving protons in hydrostatic burning are discussed first. Then I discuss triple alpha reactions in the helium burning stage. Carbon and oxygen survive in red giant stars because of the nuclear structure of oxygen and neon. Further nuclear burning of carbon, neon, oxygen and silicon in quiescent conditions are discussed next. In the subsequent core-collapse phase, neutronization due to electron capture from the top of the Fermi sea in a degenerate core takes place. The expected signal of neutrinos from a nearby supernova is calculated. The supernova often explodes inside a dense circumstellar medium, which is established due to the progenitor star losing its outermost envelope in a stellar wind or mass transfer in a binary system. The nature of the circumstellar medium and the ejecta of the supernova and their dynamics are revealed by observations in the optical, IR, radio, and X-ray bands, and I discuss some of these observations and their interpretations.

Musical Numerology

Why the Kirnberger Kernel Is So Small discusses some interesting numerical coincidences in the most commonly used musical scale.

Open Problems in HadronPhysics

Confinement & Chiral Symmetry Breaking: The fundamental problems of hadron physics

Some of the difficulties arising when one tries to understand confinement as well as dynamical and anomalous chiral symmetry breaking are reviewed. Criteria to be fulfilled by a successful and complete picture of these phenomena are presented, and a few of the suggested explanations are listed.

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".

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.

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.

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.

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.

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

FUNDAMENTALS OF STATISTICAL 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.

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.

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.

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.

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

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.

Swoopo

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.

Spontaneous Symmetry Breaking

FROM BCS TO THE LHC

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.

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.

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.

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!

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.

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.

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.

Valentini's Critique of Quantum Theory

Is Quantum Mechanics Tried, True, Wildly Successful, and Wrong?

A skeptical physicist charges that his field has been wandering in a philosophical wilderness for 80 years. The good news: He thinks he knows the way out.

Many of Antony Valentini's other papers can also be found at arXiv by clicking on the author's name in this link: Quantum Theory at the Crossroads: Reconsidering the 1927 Solvay Conference

We reconsider the crucial 1927 Solvay conference in the context of current research in the foundations of quantum theory. Contrary to folklore, the interpretation question was not settled at this conference and no consensus was reached; instead, a range of sharply conflicting views were presented and extensively discussed. Today, there is no longer an established or dominant interpretation of quantum theory, so it is important to re-evaluate the historical sources and keep the interpretation debate open. In this spirit, we provide a complete English translation of the original proceedings (lectures and discussions), and give background essays on the three main interpretations presented: de Broglie's pilot-wave theory, Born and Heisenberg's quantum mechanics, and Schroedinger's wave mechanics. We provide an extensive analysis of the lectures and discussions that took place, in the light of current debates about the meaning of quantum theory. The proceedings contain much unexpected material, including extensive discussions of de Broglie's pilot-wave theory (which de Broglie presented for a many-body system), and a "quantum mechanics" apparently lacking in wave function collapse or fundamental time evolution. We hope that the book will contribute to the ongoing revival of research in quantum foundations, as well as stimulate a reconsideration of the historical development of quantum physics. A more detailed description of the book may be found in the Preface. (Copyright by Cambridge University Press (ISBN: 9780521814218), expected publication date 2007.)

Cosmic Reionization

Computer Simulations of Cosmic Reionization

The cosmic reionization of hydrogen was the last major phase transition in the evolution of the universe, which drastically changed the ionization and thermal conditions in the cosmic gas. To the best of our knowledge today, this process was driven by the ultra-violet radiation from young, star-forming galaxies and from first quasars. We review the current observational constraints on cosmic reionization, as well as the dominant physical effects that control the ionization of intergalactic gas. We then focus on numerical modeling of this process with computer simulations. Over the past decade, significant progress has been made in solving the radiative transfer of ionizing photons from many sources through the highly inhomogeneous distribution of cosmic gas in the expanding universe. With modern simulations, we have finally converged on a general picture for the reionization process, but many unsolved problems still remain in this young and exciting field of numerical cosmology.

Graphene

Graphene: Status and Prospects

Graphene is a wonder material with many superlatives to its name. It is the thinnest material in the universe and the strongest ever measured. Its charge carriers exhibit giant intrinsic mobility, have the smallest effective mass (it is zero) and can travel micrometer-long distances without scattering at room temperature. Graphene can sustain current densities 6 orders higher than copper, shows record thermal conductivity and stiffness, is impermeable to gases and reconciles such conflicting qualities as brittleness and ductility. Electron transport in graphene is described by a Dirac-like equation, which allows the investigation of relativistic quantum phenomena in a bench-top experiment. What are other surprises that graphene keeps in store for us? This review analyses recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.

The Evolution of Sex

On the Origin of Sexual Reproduction

Sexual reproduction is costly, so what are the benefits? One of the hypotheses has a catchy name: the Red Queen theory - from the Lewis Carroll character who tells Alice she must keep running faster just to stay in the same place. In biology it's the theory that organisms have to keep changing to keep ahead of their parasites. The recombination of characteristics in sexual reproduction may help.
The widespread system of sexual reproduction found in humans and many other eukaryotes alternates haploid and diploid stages. In humans the gametes (egg and sperm) are hapolid, they only have one copy of each chromosome, while embryos and adult forms are diploid, they have two copies of each chromosome. There's an elaborate mechanism, meiosis, which converts the diploid form into the haploid form. There's another mechanism, ferilizaton, which goes from two haploid forms (the egg and sperm) to the diploid form.

The Evolution of Meiosis From Mitosis

... if there is one event in the whole evolutionary sequence at which my own mind lets my awe still overcome my instinct to analyse, and where I might concede that there may be a difficulty in seeing a Darwinian gradualism hold sway throughout almost all, it is this event—the initiation of meiosis. W. J. HAMILTON (999, p. 419)

THE origins of meiosis in early eukaryotic history have never been satisfactorily explained. Since the reduction-division process in meiosis is essential for sexual life cycles, discussion of the origins of meiosis has been closely tied to debates about the evolutionary value of sex itself and the selective pressures for its maintenance. Yet the cytological events involved in the origins of meiosis are as puzzling as the question of selective pressures. While meiosis almost certainly evolved from mitosis, it has not one but four novel steps: the pairing of homologous chromosomes, the occurrence of extensive recombination between non-sister chromatids during pairing, the suppression of sister-chromatid separation during the first meiotic division, and the absence of chromosome replication during the second meiotic division. This complexity presents a challenge to any Darwinian explanation of meiotic origins. While the simultaneous creation of these new features in one step seems impossible, their step-by-step acquisition via selection of separate mutations seems highly problematic, given that the entire sequence is required for reliable production of haploid chromosome sets. Both Maynard Smith (1978) and Hamilton (1999) regarded the origins of meiosis as one of the most difficult evolutionary problems.

This article discusses something which always bothered me. In meiosis, the chromosomes are replicated first, resulting in four copies of each homolog chromosome. But each gamete requires only one copy. Why not seperate into two gametes directly, without the initial replication - it seems simpler. Apparently, since meiosis evolved from mitosis, and the initial replication is very similiar to what happens in mitosis, it is a relatively simple evolutionary change.

Thus, and perhaps counterintuitively, the evolution of two-step meiosis requires fewer new events than the seemingly simpler one-step process

This article proposes that the main benefit of meiosis is prevention of damage during recombination. Recombination itself is helpful for repairing damaged chromosomes.

Wavefunction Uncollapse

Uncollapsing the wavefunction by undoing quantum measurements

We review and expand on recent advances in theory and experiments concerning the problem of wavefunction uncollapse: Given an unknown state that has been disturbed by a generalized measurement, restore the state to its initial configuration. We describe how this is probabilistically possible with a subsequent measurement that involves erasing the information extracted about the state in the first measurement.

Fool's Gold

Fool's Gold: How the Bold Dream of a Small Tribe at J.P. Morgan Was Corrupted by Wall Street Greed and Unleashed a Catastrophe. Author Gillian Tett follows the staff of J.P. Morgan as they developed new financial instruments (various kinds of derivatives) to better manage risk - and which ended up being used in very risky ways that significantly contributed to the current financial meltdown.

Carlos Castenada

Carlos Castenada was a UCLA anthropology student who wrote a popular series of books in the 1970's about his research into the practices of native Mexican "sorcerers" which included the consumption of psychoactive plants. As it turns out, he also had a cult, based in Los Angeles, largely of women devotees, some of whom were supposed to be witches. When Castenada died of cancer in the late nineties, five of the women disappeared without a trace - it is assumed they committed suicide. A skeleton found in Death Valley was identified as one of the "witches" in 2006. See The dark legacy of Carlos Castaneda in Salon and The Sorcerer's Apprentice: My Life with Carlos Castaneda by Amy Irving.

Isotope Separation

SWU for U and Me by Jeremy Bernstein. Urananium isotope seperation has been in the news of late because of Iran's efforts in this arena. This paper explains some of the theory behind gas centrifuges and some of the fascinating history as well. If equations aren't your cup of tea, try skipping past those sections to the ancedotes.

The Evolution of Cell membranes

Cell membranes are largely composed of phospholipids. Phospholipids in turn are built on a glycerol phosphate. The are two different glycerol phosphates in use, glycerol-1-phosphate (G1P) and glycerol-3-phosphate (G3P). The archaea use G1P and the eubacteria and the eukaryotes use G3P. The two phospholipids are synthesized in entirely different ways. The mystery is, how did two such different systems evolve, and what was the nature of the common ancestor? Compounding the mystery, eukaryote transciption and translation is similiar to the archea, while eukaryote cell membranes are similar to bacteria. See Ancestral lipid biosynthesis and early membrane evolution and archea cell membranes.

Julian Schnabel

The Nerve and the Will is a beautiful review of the work of Julian Schnabel, in the New York Review of Books.