The best of the rest from the Physics arXiv this week

Quantum Energy Teleportation with a Linear Harmonic Chain

Astronomy in Antarctica

Quantum Spring from the Casimir Effect

Dreams, Endocannabinoids And Itinerant Dynamics In Neural Networks: Re-Elaborating Crick-Mitchison Unlearning Hypothesis

Preparation Of Carbon Nanotubes At Room Temperature

I’ve argued “school functions in part to help folks accept workplace domination,” said modern workplaces don’t reward creativity, and cited evidence that schools discourage creativity:

Creativity and mental flexibility are directly penalized in terms of school grades, holding constant test scores, Citizenship, and Drive to Achieve.

So I’m not surprised to learn creativity has been falling for decades:

In the 50 years since Schwarzrock and the others took their tests, scholars … have been tracking the children. … After analyzing almost 300,000 Torrance scores of children and adults. Kim found creativity scores had been steadily rising, just like IQ scores, until 1990. Since then, creativity scores have consistently inched downward.

HT to Alex, who is skeptical:  ”I am not at all convinced that creativity is on the decline.” Me, I’m surprised the decline didn’t start earlier.  More tidbits on creativity:

A recent IBM poll of 1,500 CEOs identified creativity as the No. 1 “leadership competency” of the future. … The age-old belief that the arts have a special claim to creativity is unfounded. When scholars gave creativity tasks to both engineering majors and music majors, their scores laid down on an identical spectrum. … Preschool children, on average, ask their parents about 100 questions a day. Why, why, why—sometimes parents just wish it’d stop. Tragically, it does stop. By middle school they’ve pretty much stopped asking. It’s no coincidence that this same time is when student motivation and engagement plummet. … When creative children have a supportive teacher—someone tolerant of unconventional answers, occasional disruptions, or detours of curiosity—they tend to excel. When they don’t, they tend to underperform and drop out of high school or don’t finish college at high rates.

CEOs may give it lip service to creativity, but their actions speak much louder than their words. Most (not all) workplaces punish creativity, and while that situation remains most schools will drill it out of kids as well.

"If you only look at a person through one lens, or only believe what you're told, you can often miss the truth that is staring you in the face." -Kevin Spacey

One of the most powerful ideas from Einstein's theory of Gravity -- General Relativity -- is that any massive object in the Universe not only causes a gravitational force on other masses, but also bends light!

This was confirmed in 1919 by observing the positions of stars during a total solar eclipse; the stars closest to the Sun had their apparent position shift due to the gravitational bending of the light rays!

How does this happen? The mass acts just like a lens does, bending the light rays! Only, instead of being a glass, plastic or acrylic lens, it's a gravitational lens.

In 1936, Fritz Zwicky, the same guy who theorized the existence of dark matter, realized that distant galaxies could act as gravitational lenses also! After all, they have mass, and if there are other objects emitting light behind them, that light could get bent towards us!

Although it wasn't discovered observationally until 1979, this phenomenon, known as strong gravitational lensing, has given us some of the most remarkable images in the Universe.

Those weird arcs in the above image -- of cluster Abell 370 -- are due to gravitational lensing. Gravitational lensing is great for distorting the light from background objects, and therefore for distorting the shapes of lensed galaxies.

Any other neat effects of gravitational lenses?

Multiple images! Do you see what looks like five bright blue stars (with crosshair-style rays) in the image above? Those are actually five multiple images of the same quasar! In many of the images, you can actually see the host galaxy that the quasar resides in!

In fact, just two years ago, we discovered an incredible alignment of three objects nearly all in a perfect row from our vantage point. What does that give us?

Two almost perfect, concentric rings!

It turns out that there's only one thing that determines how much (and what type of) bending we get, given your galaxies in a certain place. All that matters is the mass of the thing acting as a gravitational lens! So if I put down a distant galaxy in the background and then a lens in the foreground, by observing what the background light does, I can easily figure out how much mass is in the lens. In fact, there are software packages out there that will even do it for you.

This is true whether it's a galaxy, a cluster of galaxies, or an individual star doing the lensing. But that's usually not such a big deal. After all, by observing a galaxy, a cluster of galaxies, or an individual star, we can usually learn a lot about its mass from other means.

But you know what would be a huge advance?

If we could find something of unknown mass acting as a gravitational lens!

Well, there's a new paper out (with some great new images) by two joint teams from Caltech and Ecole Polytechnique Federale de Lausanne, respectively, led by George Djorgovski and Georges Meylan. And they found exactly that, for the first time.

Instead of a star, galaxy, or cluster of galaxies, the object acting as a lens is a quasar (shown below), where the galaxy its found in is completely obscured by the blazing core!

Under normal circumstances, we'd never be able to know the mass of the galaxy housing this quasar. But because of the gravitational lens, we can figure it out!

Want to know something that makes this even more amazing? This image was taken from the ground, with all of the Earth's atmosphere to contend with! It is amazing how good adaptive optics have gotten!

And thanks to these observations, this is the first time we've ever seen a quasar act as a strong gravitational lens!

And what they found is that there's a mass of 22 billion Suns within the innermost kiloparsec (about 3,000 light years) of this quasar and its host galaxy!

This is the very first time this technique has been used to measure the mass of a quasar's host galaxy, and the very first time we've seen a quasar act as a gravitational lens! You can bet it won't be the last. So, welcome to the birth of a new way to do astronomy, and enjoy the images and analysis from this first discovery!

Read the comments on this post...

Providing Students and Teachers With a Wealth of Resources in the Physical Sciences

Students, does this sound familiar?

You need information about the environment, physics, chemistry, or the earth and don't know where to go. And your teacher says that the information you reference must be authoritative. Plus, you need the information fast.

No problem!

The U.S. Department of Energy (DOE) - a Dream Festival Partner - is an excellent resource. DOE will sponsor 11 highly informative, interactive exhibits in the Festival's Expo this October at the National Mall in Washington, DC, in addition to equally exciting exhibits by DOE National Laboratories.

Immerse yourself in DOE's hands-on presentations! Explore how physicists are harnessing energy from the sun to make clean and renewable energy. Learn how DOE's Fermilab accelerates particles to probe the most basic components of matter, and use an "accelerator" yourself to identify shapes in hidden targets. Come see a car that can run on water and sunlight ... and much more.

Students and teachers are also highly encouraged to stop by the Department of Energy's Office of Science exhibit to see and use ScienceEducation.gov, a new search tool from the Office of Scientific and Technical Information (OSTI) and the Office of Workforce Development for Teachers and Scientists (WDTS).

ScienceEducation.gov lets you quickly browse thousands of FREE and reliable government science education resources from a single place. And for teachers, the site features lesson plans, activities and other resources you may use in the classroom. Resources are getting added regularly, so visit now and visit often.

Visitors may be interested to know that the Department of Energy's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, providing more than 40 percent of total funding for this vital area of national importance. It oversees - and is the principal federal funding agency of - the Nation's research programs in high-energy physics, nuclear physics, and fusion energy sciences.

With such DOE expertise, be prepared to investigate the intriguing world of physical science!

In addition to DOE, its National Laboratories represented at the Expo on October 23-24 are: Ames Laboratory, Argonne National Laboratory, Brookhaven National Laboratory, Fermi National Accelerator Laboratory, Jefferson Lab, Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, National Energy Technology Laboratory, National Renewable Energy Laboratory, Princeton Plasma Physics Laboratory, Sandia National Laboratories CA, Sandia National Laboratories NM, and ORNL/Oak Ridge Associated Universities.

We thank the DOE and its National Labs and our other valued Sponsors as they join us in our goal of inspiring the next generation of scientists and engineers!

Read the comments on this post...

“The aesthetically appealing eyebrow shape has been defined by its arch, located near the junction between the medial two-thirds and lateral one-third. The position of this arch has been historically described by arbitrary anatomical landmarks that have no logical structural relationship.”

These observations feature in the latest eyebrow-related research from Dr. Bradon Wilhelmi, the Leonard J. Weiner Professor and Chief of the Division of Plastic Surgery in the Department of Surgery at University of Louisville.
Along with colleagues Sylvia Pham and Arian Mowlavi, MD, the professor examined the eyebrows of 50 subjects, taking measurements from the medial aspect of the eyebrow to the a) deep temporal fusion line (ridge), b) eyebrow peak (arch), c) lateral aspect of the brow, and d) lateral limbus. The objective of the study was determine if the deep temporal fusion line can act as a more accurate and functional landmark than prior, and some say illogical, anatomical landmarks for the eyebrow peak position. The new eyebrow measurements demonstrated that the deep temporal fusion line is the most precise indicator of brow peak position among all examined landmarks.

“The lateral limbus and medial two-thirds lateral one-third junction more accurately predict brow peak in females, but the deep temporal fusion line is an equally reliable predictor of brow peak for males and females.”

The conclusions could have implications for those contemplating (or performing) endoscopic brow lift procedures.

“These findings suggest that placement of endoscopic brow lift incisions and subsequent fixation points may be best defined along the deep temporal fusion line.”

The research is published in the Aesthetic Surgery Journal, May/June 2010; 30 (3)

Our tour of the Marianas begins SW of Guam. In this area the volcanoes are submerged and make up a region known as the Southern Seamount Province. Our first stop is Tracey Seamount, which lies 30 km west of Guam. Tracey is a ~2 km tall cone and volume of ~45 km3 It is one of the smaller volcanoes in the Mariana arc; Pagan, contains about 2200 km3 of material (Bloomer et al., 1989). It has a sector collapse on its western flank and resembles a submarine Mt. St. Helens. It was investigated by the ROV Hyper-Dolphin from the R/V Natsushima in Feb. 2009, which revealed that the cone is map up of alternating pyroclastics and dacite built on a basaltic-andesite base. A dome of dacite has formed in the collapse area. It is still considered active and that along with its proximity to Guam and its history of sector collapse suggest an underappreciated risk to the island.

Map of the volcanoes of the Marianas Islands.

Next up is West Rota. This is a large submarine caldera 40 km WNW of Rota. In fact it is the largest caldera in the IBM system, similar in size to Crater Lake in Oregon. Found in the caldera are large balls of rhyolite that are inferred to be rhyolite "balloons" that may have actually floated for a time after erupting (Stern et al. 2008). The youngest material dated so far is 37,000 years old, but there is evidence of current hydrothermal activity.

64 km of Rota and west of the main arc is the small but notable submarine volcano NW Rota 1. It is notable for being the site of the first directly observed deep submarine eruption. In 2001 it was dredged (my first cruise), but nothing unusual was noticed. In 2003 NOAA scientists detected an acidic plume above the summit. Subsequent dives by ROVs in 2004, 2005, 2006 and 2009 found continued vigorous activity, including sulfur-rich plumes, occasional small explosions and density flows of tephra down the flanks. The material being erupted is basaltic-andesite and despite the non-stop activity, no evidence has ever been observed on the surface that anything is going on down below. NW Rota is also the home to a rich ecosystem of shrimp and other organisms that are dependent on sulfur-loving colonies of chemosynthetic bacteria.

Further to the north we enter the Central Island Province, but not all volcanoes here have breached the surface. In addition to a multitude of small submarinevolcanoes, there are several larger ones: Esmeralda Bank, Zealandia Bank, Ruby and East Diamante Seamount. Several of these have some historic record of possible activity (mostly disturbed, discolored water) and Diamante has noticeable hydrothermal activity.

The islands proper start (moving S to N) with the intriguing Anatahan, which consist of overlapping calderas

Morning view of Anatahan from my room, R/V Natsushima June 2009.

Anatahan had a significant eruption in 2003 and there is an interesting story about Japanese holdouts on the island at the end of WWII that was made into little-known movie.

Sarigan is next.

Sarigan Island in the Marianas.

Recently there was a submarine eruption south of Sarigan. A cruise underway at this moment may, if time permits, send an ROV to visit the presumed eruption site.

Guguan last erupted in the 19th century. Alamagan to the north has no definitive historic record of activity, although there was a false alarm in 1999. Pagan is one of the few islands (outside of the larger Saipan, Tinian, Rota and Guam) to have any population. Even minor activity there presents a concern due to this. Agrigan has a caldera that was the site of small eruption around 1917. The symmetrical cone of Ascuncion had reported activity early in the 20the century, but its northern neighbors, the Maug Islands, have no historic eruptions and are in fact the eroding remnants of a caldera. Further north we enter another seamount province, except for Uracas or Farallon de Pajaros. This particular volcano and its submarine neighbors seem to be particularly restless. North of FdP is considered to be the end of the Marianas and the start of the Bonin or Volcano Islands.

Guguan and Alamagan Islands in the Marianas. Image by Ed Kohut.

References
Bloomer, S. H., Stern, R. J., and Smoot, N. C. "Physical Volcanology of the Submarine Mariana and Volcano Arcs." Bull. Volcanology, 51, 210-224, 1989.

Gill, J., Klemperer, S., Stern, R., Tamura, Y., and Wiens, D. 2003. 'Subduction-Factory' Meeting Studies Izu-Bonin-Mariana Margin. Eos, v. 84, No. 1, p. 3

Stern, R.J., Fouch, M.J., and Klemperer, S., 2003. "An Overview of the Izu-Bonin-Mariana Subduction Factory" in J. Eiler and M. Hirschmann (eds.) Inside the Subduction Factory, Geophysical Monograph 138, American Geophysical Union, 175-222.

Stern, R.J., Tamura, Y., Embley, R.W., Ishizuku, O., Merle, S., Basu, N.K., Kawabata, H., and Bloomer, S.H., 2008. Evolution of West Rota Volcano, an extinct submarine volcano in the Southern Mariana Arc: Evidence from sea floor morphology, remotely operated vehicle observations and 40Ar/39Ar Geochronology. The Island Arc 17, 70-89.

Read the comments on this post...

Help to make sense of the Daily Mail’s ongoing effort to classify every inanimate object into those that cause cancer and those that prevent it.

So writes Paul Battley, who compiled a long list.

(Thanks to Metafilter for bringing this to our attention.)

What are some commutative semisimple algebras that aren't separable? john http://math.ucr.edu/home/baez/ baez@math.ucr.edu

In 1977, William Sims Bainbridge and Murray M. Dalziel wrote “New Maps of Science Fiction.” Published in Analog Yearbook [1977, pp. 277-99], it was one of the first carefully done computer-based social sciencey analyses of science fiction. The essay says (among other things):

Our computer has generated many more maps of science fiction, enough for a small atlas, several using rather sophisticated mathematical techniques: factor analysis, similarity matrix analysis, and multidimensional scaling. But we think we have already made our point: standard sociological survey techniques can be used to make reliable maps of science fiction or any other kind of literature. When social scientists explain their findings to the public, they walk an unpleasant tightrope. If the findings make too much sense, people will say, “Oh, we knew that all along. Big Deal. ” If the findings are strange and surprising, people will refuse to believe them. Damned if we do and damned if we don’t.

Many of the results we have presented here will make sense to science fiction readers. We hope that fact will give you some confidence in our methods. Perhaps you also have a sense that questionnaires can produce a tremendous amount of unexpected information when subjected to scientific analysis….

(Thanks to investigator Rose Fox for bringing this to our attention.)

Two recent articles on survivalists:

1. “From the outside, Jerry Erwin’s home … is a nondescript house … But tucked away out of sight in his backyard are the signs of his preparations for doomsday, a catastrophic societal collapse that Erwin, 45, now believes is likely within his lifetime. … Erwin and others like him in the United States and elsewhere see political upheaval and natural disasters as clear signs that civilization is doomed.” (more; HT J Hughes)
2. “Vivos goes all out by promising a survival shelter stocked with power generation, water wells, filtration systems, sewage disposal, a year’s supply of food, security devices and medical equipment. Of course, you’ll need all that if you believe disaster may strike at any moment because of a polar shift, super volcano eruptions, solar flares, nuclear war, and `even the return of Planet X (known as Niburu or Nemesis),’ Vivos cheerfully states. Did we mention that there’s a 2012 countdown clock on the company website?” (more)

Sadly, as with cryonics patients, while survivalists do society a great good, the media mostly snickers at them. This makes sense when you realize: Charity Isn’t About Help. Given a choice between praising acts that show devotion and loyalty, or acts that actually help, humans usually praise loyalty.

On the good: The world faces existential risk, i.e., a risk that the world will die.  Such a death is bad not only for those who live here now, but also for vast future generations who might descend from us now.  Cultures and ethnicities face related risks.  By preparing to save themselves under various disaster scenarios, survivalists also tend to make their culture, ethnicity, and world a bit less likely to die.  An effort for which future generations should be quite grateful.

On snickering:  On average, survivalists tend to display undesirable characteristics. They tend to have extreme and unrealistic opinions, that disaster soon has an unrealistically high probability.  They also show disloyalty and a low opinion of their wider society, by suggesting it is due for a big disaster soon.  They show disloyalty to larger social units, by focusing directly on saving their own friends and family, rather than focusing on saving those larger social units.  And they tend to be cynics, with all that implies.

For those with a theoretical interest in zombies, investigator Mark Siegel recommends Daniel Drezner’s essay in the July/August 2010 issue of the journal Foreign Policy. Siegel says a colleague of his, Doug Edwards, says: “At last, a well-reasoned treatise on the potential effects of a zombie invasion on international politics.” Say what you will, the essay begins:

There are many sources of fear in world politics — terrorist attacks, natural disasters, climate change, financial panic, nuclear proliferation, ethnic conflict, and so forth. Surveying the cultural zeitgeist, however, it is striking how an unnatural problem has become one of the fastest-growing concerns in international relations. I speak, of course, of zombies.

For our purposes, a zombie is defined as a reanimated being occupying a human corpse, with a strong desire to eat human flesh…

In the comments following the silly accelerator poll, onymous wrote:

[T]he point of the LHC isn't to discover the Higgs. No one in their right minds would build a 14 TeV pp collider if their only goal was to discover the Higgs.

While it's true that the ultimate goal of the LHC is to discover more exotic particles that may or may not exist (blah, blah, supersymmetry, blah) most of the hype has focussed on the Higgs, which is the one thing they're pretty sure they'll find (comments later in that thread notwithstanding). This is one of the potential problems with the way the machine has been marketed, but that's a whole different topic.

I did want to pick up on one thing, though, that relates to this question in a slightly different way, and that's the big difference between the masses of the particles being sought and the machines that are used to look for them. Looking at the rumors that kicked this off, after all, they're talking about a Higgs boson with a mass of around 150 GeV. The Tevatron, where they're doing these experiments, already has an energy of around 2000 GeV (or 2 TeV), a full factor of ten bigger than the mass of the particle they're trying to create. The LHC, when it eventually reaches its full energy, will be another factor of almost ten bigger than that.

So, why do you need such a big accelerator to look for such a small particle? If the goal is just to have enough energy to create the Higgs by converting the energy of the colliding particles into mass (E = mc2, baby), why do you need more than a few hundred GeV?

There are lots of ways to answer this, but they mostly come down to one thing: while the colliding particles may have a huge amount of energy, you almost never get to use all of it.

Read the rest of this post... | Read the comments on this post...

It's a pretty nice time for quantum optics and laser physics at Texas A&M, with us moving into a brand new lab and acquiring several new laser systems. One of the systems we're moving isn't new (we've had it for a few years, and the technology is considerably older), but we're about to put it to work on a new project. It's a relatively high-power Nd:YAG laser.

The operating parameters are about 2.5 joules per pulse, with 10 pulses per second for an average power of 25 watts. Each pulse is about 8 nanoseconds long. This is a rather hefty amount of light. Though any Class 4 laser requires serious attention to safety, we're going to treat this one pretty much like a nuclear reactor when it's running.

Now as you may know, light carries momentum and can exert pressure on surfaces that it hits. This is true even in the purely classical field theory of Maxwell. But as a rule we don't notice light pressure because it's so slight. I'm a little curious as to whether it might be significant in a laser this intense. Let's run the numbers and see what happens.

First, let's review some definitions. Power is measured in watts, and it's the number of joules per second. We'll label it with a capital P. Pressure is force per area, and we'll label it with a lower-case p. Intensity is what you might colloquially think of as the brightness, and it's just the power per area, and we'll use capital I for it. The relationship between light pressure and light intensity is given by:

Where c is as usual the speed of light. Now if pressure is force per area and intensity is power per area, than the force will be given by the total power divided by c:

These are just two ways of saying the same thing. We'll start with the second one. 25 watts divided by the speed of light is: 8.34 x 10-8 N. Very slight, as you might expect because 25 watts isn't actually much power. It's just a lot for a laser because it's kept in a very tight beam. But this is a laser and the beam is very tight. It can be focused on something very small. What if we focused the laser on a grain of sand? To simplify the math, say it's a tiny cubic crystal of sand with each side having a length of 0.25mm. Sand is frequently quartz, which has a density of about 2.6 grams per cubic centimeter. As such the grain of sand has a mass of around 40 micrograms. Force is mass*acceleration, so the acceleration the grain will be about 2.05 m/s^2. This is quite a bit, certainly enough to send it sliding across the table.

Well, unless we blow it to smithereens. Remember that 25 watts is an average. The instantaneous power during the pulse is actually about 2.5 joules / 8 nanoseconds, which is about 312 million watts. Focused onto that (0.25 mm)^2 cross section, that's an intensity of 5 x 1013 watts per square meter. Yikes, that's about 50 billion times more intense than direct sunlight. The pressure works out to be relatively modest - I think around 25 PSI (167 kPa) - so I'm not sure mechanical stress will break up our sand grain. However, the light that's absorbed might be enough to melt it, especially with repeated pulses. I'm not sure what the absorbance of sand is at 1063/532nm wavelengths.

Sadly I'm pretty sure I won't be allowed to try this experiment to find out. Frankly I think my self-preservation instinct might veto my "Holy cow, lasers!" instinct anyway. Still, it's tempting...

BLOGGY NEWS: I will be spending the next two weeks in the scenic but very small town of Casper, WY at a quantum optics / laser physics conference/school being held by our own no-kidding legendary Marlan Scully. There's a decent bit of downtime involved, and supposedly the place is quite scenic. As such I hope to be doing a bit of a travelogue, with summaries of some of the talks and pictures of the landscape. At any rate it can't possibly be any hotter than College Station is!

Read the comments on this post...

MVP 23 revealed ... and 24 introduced!

Mystery Volcano Photo #23 was, in fact, Middle Sister volcano in Oregon, part of the picturesque Three Sisters near Bend. Middle Sister is a partially eroded (by glaciers) composite volcano with a mix basaltic andesite to andesite lava flows and tephra deposits. Depending on who you speak with, Middle Sister gets lumped in with North Sister (as Middle Sister build up on the flanks of its slightly older sibling) or stands on its own as a part of the Three Sisters. However, before thinking Middle Sister is dormant, remember, the last eruption might have been as recent as ~440 A.D.

Current Standings:
The Bobs - 3
Don Crain - 3
Boris Behncke - 3
gijs - 2
volcanista - 1
Lockwood - 1
Elizabeth - 1
Ralph - 1
Anne - 1
Cam - 1
gg - 1
Damon Hynes - 1
Marco - 1
Doug C. - 1
Diane - 1
Stephen - 1
MK, Alberta - 1
Kultsi - 1

And now, here is another mystery photo (and it might be a doozy).

Click on the image to see a larger version.

Good luck!

Read the comments on this post...

If you have a problem with surfeit of birds or a lack of avalanches, this invention offers a possible dual solution:

NOISE GENERATING DEVICE TO SCARE BIRDS OR TRIGGER AVALANCHES, Michael Eggers, US patent application number: 12/303,141, Filing date: Jun 5, 2007.

Physicists have finally discovered why a blue pigment used by the Mayans lasts so long.

The Maya civilisation flourished in central America from 2500 BC until the arrival of the Spanish in the 17th century. During that time it developed a complex written language as well as impressive architecture and art.

One of the features of this art is a vivid colour called Maya Blue which amazingly survives until today. Maya Blue has long puzzled archaeologists because of its remarkable longevity. How does it survive when other pigments fade away?

Today, Catherine Dejoie at the Néel Institute in Grenoble et amis provide an answer. They use x-ray diffraction and thermogravimetric analysis (which uses changes in weight to determine how the breakdown in materials occur) to determine the structure of the material. This in turn has revealed the secret of its longevity.

Archaeologists know that Maya Blue is made by heating the organic pigment indigo with palygorskite, a type of fibrous clay found in Yucatan. During this heating process, the indigo is somehow absorbed into the fibrous clay and this fixes the colour. But how this processes increases the longevity of the pigment hasn't been known until now.

Dejoi et amis say that the clay fibres contain channels filled with water molecules. Their analysis shows that the heating process causes the water to boil away, allowing the indigo to enter these channels. When the material cools down, these channels then become sealed by "gatekeeper" molecules that prevent the indigo from getting out again.

That partly explains the longevity but there is another mechanism at work too. Dejoi et amis say that indigo looses its colour and becomes yellow when a carbon-carbon double bond in the pigment is broken. However, this cannot happen in Maya Blue because this bond is protected by the clay channels, a phenomenon known as steric shielding.

"We thus believe that fixing of the indigo molecule to sterically screened sites mainly accounts for the chemical stability of May Blue," say Dejoi and co.

The discovery of the secret of Maya Blue could have important implications for pigment manufacturers. Dejoi and pals say that now they know why Maya Blue is so long lasting, the same trick can be used for other colours too.

They even reveal the first new pigment designed in this way: a new kind of blue in which indigo is embedded in microporous zeolite which performs the same protective function as the palygorskite clay.

That, they say, is the birth of the new discipline of archaeomimetics in which the molecular structure ancient pigments is inspiring a new generation of long-lasting colour.

Fascinating stuff!

Ref: arxiv.org/abs/1007.0818: Revisiting Maya Blue and Designing Hybrid Pigments by Archaeomimetism

"I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use." -Galileo Galilei

Geez, Ethan, why don't you take on a bigger question?

This question of "fundamental things" has a special meaning to scientists and natural philosophers, going all the way back to Thales of Miletus, 2600 years ago, who began asking about the arche (αρχή), which is the "element" or "prime cause" of existing things.

Of course, the scientific enterprise was just beginning, so you can't fault Thales too much for coming up with "water". But I totally credit him with this great idea, that's governed all of scientific progress ever since:

Natural phenomena are explicable by the natural workings of the Universe.

(I'm paraphrasing, of course.) This, to me, is the greatest power of science: you can observe the way many things work, determine what laws they follow, and then generalize those laws to explain (and even predict) new phenomena. So come forward to the present day. Where are we now?

This is the standard model. (Click above for a huge, poster-size image.) We have found a few different types of particles in the Universe with different masses, charges (both electrical and color), and spins (i.e., intrinsic angular momentum). As far as we know, these particles are "fundamental" in the sense that they cannot be broken down any further.

But they do more than exist. These particles also interact, which (in our language) means they exert forces on each other, and they sometimes also react in various ways, turning some fundamental particles into others. Three of the fundamental forces work by exchanging particles,

while gravity, lacking such a successful description of its force, works by mass (and other forms of energy) deforming spacetime.

So in a nutshell, that's how everything we know works. These indivisible components of the natural world, with just a few fundamental properties (like mass, charge, and energy) and laws under which they interact, make up everything we know of in the Universe.

There are also secondary quantities that, while we don't think of them as fundamental, play important roles in figuring out physical phenomena. I'm talking about quantities like Temperature. Heat, a form of energy, is what we think of as a fundamental quantity, but temperature is often more useful to talk about as a measurable quantity. For example, there are a number of people who get upset about the Sun's Corona because of its temperature.

"The Sun's Corona is at a higher temperature than the surface of the Sun. OH NO!" But the Sun's Corona is incredibly diffuse, and would do a far worse job of, say, cooking your pizza, than the Sun's surface would. Why? The Corona has far less heat and energy than the Sun's surface. Looking at fundamental quantities gives us an interesting perspective here. While there's an interesting question of "how" to be answered concerning the Corona, its high temperatures don't represent a fundamental problem with the way we think about the Universe.

In other words, we don't go home at night worried that our understanding of the Universe will never be complete because of the temperature of the Sun's Corona.

But gravity is a problem, in that sense. We don't know what causes it at a fundamental level. There are two major -- seemingly unrelated -- problems with it.

The first one is that general relativity is so mind-bogglingly difficult to work with. If I give you a flat, empty Universe, Einstein's theory of gravity tells me what any particle in that Universe will do. Namely, remain in motion, unchanged by anything around it.

BOR-ING! What if we put one point mass in that Universe?

Well, now things are hard. If you've just got a mass, you've got this spacetime. If your mass is also charged, you've got this one. Massive and spinning? Try here. And massive, spinning, and charged? That's this one.

You want to put a second mass in the Universe? Good luck with that analytically unsolvable problem. Our Universe, by the way, has about 1090 particles in it, so... well, in any case, that's the first problem with gravity.

What's the second?

We don't even know what causes gravity, at a fundamental level. Is there such a thing as a graviton? No one's sure. (Well, some people are sure, but those people aren't necessarily right.) Some people hope for a theory of quantum gravity, most of whom pin their hopes on string theory.

These ideas are not without their problems, which I won't go into here in detail. But there is a new idea out there this year, courtesy of Erik Verlinde.

The basic idea is that gravity is just a consequence of thermodynamics. (For an explanation of how one could visualize this, go here.)

It's been getting a lot of press and a lot of people have been taking it up. I read the original paper and some follow-ups, and here's my take. I want to state that there's nothing that makes it inherently, obviously wrong. But there's a very important assumption that one needs to make in order to take this idea seriously, that may not be based in reality.

First, there's this idea that people throw around very frequently, known as duality. Here's a definition from wikipedia:

If two theories are related by a duality transformation, it means that the first theory can be transformed in some way so that it ends up looking just like the second theory. The two theories are then said to be dual to one another under that kind of transformation. Put differently, the two theories are mathematically different descriptions of the same phenomena.

Here's the deal, though. You can't just change your variables, say "I'm the dual of gravity," and be done with it. You need to ask yourself, "are my dual variables still physical descriptors of the same phenomenon?"

There's an old example from general relativity, back in our "Universe with one mass" model.

If I stand a distance r away from the black hole (of Schwarzschild radius R), I can describe any point in this Universe using the parameter r/R.

But dual to that is that at any point inside the Schwarzschild radius, which can be described by R/r. There's a huge problem with that, though.

We have no information about what goes on inside of that black hole, and whether our descriptions are accurate at all. The math looks the same, but the physics may be very, very different. In other words, what happens outside of the black hole is physically meaningful, and describes fundamental forces. The dual transformation, with the flipped variables? Not necessarily.

Verlinde's idea hinges on his assumption of the duality between gravity and thermodynamics (or entropy) being a physically valid one.

And if he's right, this could lead to some potentially interesting avenues of inquiry. But there's a huge difference between two things being mathematically equivalent and being physically equivalent, and I am not yet convinced of the latter. Especially because I don't think of entropy as being all that fundamental. If I take a physical system, I can measure its entropy, but I can measure its temperature, too. But if I give you the energy, positions, and momenta of every particle in there, you can give me the entropy. If you give me the entropy... the reverse isn't true.

But I've got this old-fashioned picture of how the Universe works in my head. In this picture, particles are the most fundamental things, and something's got to cause the forces between them. Are they other particles? Is it a curving of spacetime? Or is it something else? At this point, all of the ideas out there are speculative and purely mathematical, because nature is slow to give her clues away. So you'll hear more about these ideas from the news media and from scientists, because we just don't know yet.

So there is this new idea out there, and while it isn't necessarily crazy, it isn't necessarily right or physically meaningful either. Hope this helps give you a little perspective!

Read the comments on this post...

By Dr. Cynthia B. Phillips
Planetary geologist at the Carl Sagan Center for the Study of Life in the Universe, SETI Institute

Jupiter's moon Europa could be the best place beyond the Earth to search for life. This small moon, about the size of Earth's Moon, is one of the Galilean moons first discovered 400 years ago by Galileo. The Galilean moons were the first objects observed to orbit another planet, and they revolutionized the way our solar system was understood.

Today, the moons of Jupiter are known to be a scientifically rich part of our solar system, and they are yielding a new revolution in our view of the possibilities for extraterrestrial life. Europa, in particular, may hold the key to understanding the potential for life in our solar system and beyond. Scientists believe that habitability, or the ability of life to survive on a particular world, requires liquid water, the correct chemical elements, and a sufficient source of energy. Beyond the Earth, Mars and Europa are the best places to search for life in our solar system, and Europa is unique because it is believed to have a large ocean of liquid water fairly close to the surface today, underneath its icy crust.

The Galileo spacecraft, which orbited Jupiter from 1995 to 2003, made observations of Europa and the other Galilean moons, and then it was intentionally crashed into Jupiter to avoid any potential contamination of Europa. Galileo observations revealed a smooth, bright icy surface, criss-crossed by an intricate web of fractures and ridges. Scientific analyses of data from its instruments confirmed the probable existence of a layer of water about 50 miles thick beneath the ice. This means that Europa could have more water than in all of the Earth's oceans combined!

Artist's conception of a future mission in orbit around Europa Image credit: Mike Carroll, NASA/JPL/Caltech

NASA is currently planning the Europa Jupiter System Mission (EJSM) to follow up on these discoveries. EJSM is an international project, and includes a NASA-built Europa orbiter and a Ganymede orbiter to be built by the European Space Agency. Both spacecraft would study the entire Jupiter system, as well as their targeted moons. Development of such a mission requires a very long lead time, however - even if design and construction of the spacecraft started now, the first Europa data wouldn't be received until 2024!

Exploration of the outer solar system helps us understand not only the habitability of our own solar system, but also the potential for life in other solar systems. Many of the "exoplanets" that have been recently discovered orbiting other stars are giant planets, much more similar in size to Jupiter than to the Earth. While it is unlikely that such giant planets would be habitable, it is quite possible that these other Jupiters have moons orbiting them just like the Galilean moons. If Europa is an inhabited world in our own solar system, this increases the chance that similar moons could be abodes for life in distant solar systems throughout the universe.

The Europa Jupiter System Mission concept is a mature one, and much work has been done over the past decade to mitigate the radiation challenges that come with operating a Europa spacecraft deep inside the radiation belts of Jupiter's strong magnetic field. A mission to Europa has consistently emerged as the top outer solar system flagship-class mission in studies by NASA and the US planetary science community. It is time to commit funding and resources to making this vision a reality.

To learn more about Galileo's 400 years of discovery, the relevance of outer solar system exploration, and the plans for EJSM, visit a special exhibit in Washington DC at the Rayburn House Office Building on Thursday, July 15th. This exhibit is open to the public.

Read the comments on this post...

Via Crooked Timber, there's a silly web site that lets you put in a chunk of text, and does some sort of statistical analysis of it to determine what famous writer's prose it most closely resembles. It turns out, I'm kind of hard to categorize.

For instance, when I'm writing about Holy Grails, I apparently sound like Dan Brown. When the subject turns to the size of the proton, though, I sound like Douglas Adams.

Maybe it's just that the random variety of topics on the blog throws it off, though. I have, after all, written an entire book explaining quantum mechanics through conversations with my dog, which ought to be consistent. So, what does it make of How to Teach Physics to Your Dog?

The dog dialogue that goes with chapter 5, on the Quantum Zeno Effect evidently sounds like Mark Twain. The start of the serious explanation in that chapter, describing the historical paradox proposed by Zeno of Elea, is reminiscent of Vladimir Nabokov. Moving a little later in the book, the Bunnies Made of Cheese dialogue in which I talk to Emmy about quantum electro-dynamics bears a striking resemblance to Arthur Conan Doyle (I'm not sure which of us is Holmes). And, finally, the opening section of that chapter in which I explain the energy-time uncertainty relation is apparently hard to tell apart from the work of H.P. Lovecraft. That's probably my favorite result of the lot, given that the section in question is a breezy discussion of time and frequency illustrated by discussions of dogs wagging their tails.

I wonder if it would be possible to get those names on the cover of the paperback edition? "If you like Mark Twain, Arthur Conan Doyle, Vladimir Nabokov, or H. P. Lovecraft, you're sure to like at least part of How to Teach Physics to Your Dog..."

Read the comments on this post...

Despite their name, "high-temperature" superconductors require pretty darn cold conditions -- all far below freezing temperatures, some near absolute zero (-273 degrees Celsius) -- to operate without energy loss. As a result, they're not practical for everyday uses like more efficient power transmission -- that is, unless you have a stockpile of liquid helium or nitrogen dewars just hanging around your house.

So why can't we create room-temperature superconductors? That's a question that scientists are still trying to answer.

In research released today in the journal Nature, a team of U.S. and Japanese researchers has made a breakthrough in understanding an alleged killer of room-temperature superconductivity -- an electronic phase called the "pseudogap."

Read the rest of this post... | Read the comments on this post...