Thursday, January 31, 2013

Harappans Ate Curry

In the Indus River Valley (basically modern Pakistan), the Harappans were eating meals with the characteristic ingredients of curry (such as ginger, tumeric and garlic).

The conclusion is based on the residual remains on food infused on pottery, human teeth, and cow teeth from archaeological digs in the Indus River Valley dated to between 2500 and 2200 B.C.E.  These are the oldest discovered examples of ginger and tumeric in the region.
They found additional supporting evidence of ginger and turmeric use on ancient cow teeth unearthed in Harappa, one of the largest Indus cities, located in Pakistan west of the border with India. Why [?] . . . in the region today, people often place leftovers outside their homes for wandering cows to munch on. There are numerous ancient Indus images of cattle on terra-cotta seals, suggesting that during Indus times, people may have regarded cows as sacred, as Hindus do today. The Harappan ruins also contain evidence of domesticated chickens, which were likely cooked in those tandoori-style ovens and eaten. . . . tandoori-style ovens [are] often found at Indus sites. . .
Many archaeologists once thought that Indus peoples were restricted to a few grains like wheat and barley. But Cambridge University archaeologist Jennifer Bates, part of a joint Indian-U.K. team, has been examining the relative abundance of various crops at two village sites near today’s Masudpur, also west of Delhi. She found that villagers cultivated a wide array of crops, including rice, lentils, and mung beans. Finding significant quantities of rice was a particular surprise, since the grain was long thought to have arrived only at the end of the Indus civilization. In fact, inhabitants of one village appear to have preferred rice to wheat and barley (though millet was their favorite crop).
The evidence that Harappan culture may have been a rice eating one almost from the beginning of its golden age, that it was a culture in which cows were revered, and that its favorite recipes survived the Indo-Aryan invasion, helps to unravel the mystery of what components of Vedic culture were part of the Harappan substrate and which were instead part of the Indo-Aryan superstrate.

In particular, this evidence disfavors a hypothesis that the Harappan culture had so completely collapsed and was in such disarray upon the arrival of the Indo-Aryans, that there was no substrate influence on the income conquerors culture.  This not only lets us know something about the Harappans.  It also, by substraction, tells us what elements of early Vedic culture that it might be tempting to attribute to Proto-Indo-Europeans was in fact a Harappan substrate influence.

This also provides culturally persistent benchmarks that can be searched for in other Indo-European cultures in an effort to discern any possible distinctively pre-Indo-Aryan Harappan influences.  If all of the known cultural indicators of Harappan culture are absent from other Indo-European cultures, this is highly relevant evidence disfavoring an "Out of India" theory of Indo-European origins.

Does The Basilisk Have Roots In A Real Snake?

Many writers, some of non-fiction, and many of fiction drawing on a mixed fiction and non-fiction tradition, have written about the reputed venomous animal called the Basilisk.  Does this legend have roots in a real animal.  This post argues that it does and identifies the most likely candidate based on the earliest written account of one and the relevant candidate species of venomous reptiles.

Per Wikipedia:
One of the earliest accounts of the basilisk comes from Pliny the Elder's Natural History, written in roughly 79 AD. He describes the catoblepas, a monstrous cow-like creature of which "all who behold its eyes, fall dead upon the spot,"[3] and then goes on to say,
"There is the same power also in the serpent called the basilisk. It is produced in the province of Cyrene, being not more than twelve fingers in length. It has a white spot on the head, strongly resembling a sort of a diadem. When it hisses, all the other serpents fly from it: and it does not advance its body, like the others, by a succession of folds, but moves along upright and erect upon the middle. It destroys all shrubs, not only by its contact, but those even that it has breathed upon; it burns up all the grass too, and breaks the stones, so tremendous is its noxious influence. It was formerly a general belief that if a man on horseback killed one of these animals with a spear, the poison would run up the weapon and kill, not only the rider, but the horse as well. To this dreadful monster the crow of a rooster is fatal, a thing that has been tried with success, for kings have often desired to see its body when killed; so true is it that it has pleased Nature that there should be nothing without its antidote. The animal is thrown into the hole of the basilisk, which is easily known from the soil around it being infected. The weasel destroys the basilisk by its odour, but dies itself in this struggle of nature against its own self."[4]
Footnotes 3 and 4 are to "Pliny the Elder, eds. John Bostock, H.T. Riley (translators) (1855). "The Natural History". link. Retrieved 2009-06-10."

Cyrene is a historical province of the Roman empire basically along the western border of modern Egypt in modern Libya. 

Pliny the Elder had served as a senior Roman civil servant in Tripoli and Northern Libya about five years before his work was published, although not in Cyrene itself, and had traveled to almost all parts of the Roman empire during his career as a student, soldier, civil servant and natural philosopher.

The name "Basilisk" has Greco-Roman origins "from Latin basiliscus, from Greek basiliskos "little king," dim. of basileus "king" (see Basil); said by Pliny to have been so called because of a crest or spot on its head resembling a crown."  Thus, the name basically meant "little king snake."

Many later Basilisk accounts which arose in the Middle Ages and later, seem to be derived from Pliny's account and then exaggerated or distorted in the retelling by people in places that no longer had any cobras of any kind, and had never travelled to any place that did.

While various candidates for the origins of this myth have been suggested, discussion has focused on several kinds of snakes commonly called cobras, although from several different subtypes of them.  This post argues that the Nubian Spitting Cobra is probably the source of the Basilisk account made by Pliny the Elder in his Natural History in 79 CE.

The Case For The Nubian Spitting Snake As The Source Of The Basilisk Myth

* Pliny describes the Basalisk as a kind of serpent, which would suggest at least a reptile and probably a snake.

* The "upright and erect upon the middle" mode of locomotion language in Pliny's description is very distinctive as a means of distinguishing cobras from non-cobras.  Many species of cobras also have a distinctive hiss.

* The King Cobra, sometimes discussed, is a poor fit as it is too big to fit the "twelve fingers" description and also is native to Asia, rather than North Africa, an error that Pliny was probably too close to the source to mistake. 



* Many cobras also have distinctive hood markings that could be interpreted as a diadem pattern, but not the geographically more plausible and very lethally venomous, Desert Black Snake.  These are pure black without a diadem pattern (although juveniles in eastern North Africa have a pattern of reddish crossbars on the back), and don't look stereotypically cobra-like even though they are actually a kind of cobra, although it is not part of the distinctive Naja genus of the subfamily of snakes that that do have this distinctive appearance.  Here is what a Desert Black Snake looks like:



Black desert snakes do not spit venom.

* There are sixteen species of Naja genus cobras found in Africa or the Middle East.  But, only two of those species: the Egyptian Cobra and the Nubian Spitting Cobra would have had habitats in or near the Roman province of Cyrene in the historic era.

* The geographically fitting Egyptian Cobra looks the part, but does not spit venom, a trait present in other African cobras which could explain the myth that those who look into its eyes can be afflicted from a short distance even if they are not bitten. An image of an Egyptian Cobra is below:


* Geography (they are found in northeastern Africa in parts of Egypt, Sudan, Chad, Niger and Eritrea), the venom spitting trait, and distinctive hood markings do coincide, however, in the case of the Nubian spitting cobra.  An image of one is below:



The deadly Nubian spitting cobra "likes to hide in holes, brush piles or any other ground cover during the day. If provoked or threatened, it will raise its forebody, spread its hood and readily spit jets of venom at the face of its predator or threat. It prefers to prey on amphibians (such as frogs and toads) if and when they are available, but will feed on rodents, birds and probably snakes." 

These facts fit the notion that roosters incubate its eggs, something that could be wrongfully inferred because rooster feathers would likely be found in the Nubian spitting snake's nest. 

This also fits the notion that the Basilisk lives in burrows, and the notion that they are found in environments where shrubs and grass are present (at least until poisoned) as opposed to more lush environments where most other kinds of cobras are found.

The association with weasels is like a reference to the venom resistant cobra killing mongoose (who cobras sometimes kill by constriction), which look a great deal like weasels (and don't actually use smell to defeat cobras).  The range of the mongoose overlaps signficantly, even today, with the range of the Nubian spitting cobra.

Tuesday, January 29, 2013

Munda As Intrusive To India

The Origins of the Munda People

Razib Khan confirms at the Gene Expressino blog, with independent DIY autosomal genetic analysis, what previous linguistic, archaelogical and Y-DNA evidence had already strongly suggested: the Austro-Asiatic language subfamily of South Asia, called the Munda languages, now spoken by about 9 million people in the Northeastern part of South Asia were intrusive to South Asia from Southeast Asia, rather than the other way around.  The Austro-Asiatic languages are best known for the Vietnamese and Khmer (Cambodian) languages.  These languages have their roots probably in the hills of southern Yunnan in China," between 4000 BCE and 2000 BCE. (As an aside, Recent Y-DNA phylogeny evidence also supports the proposition that people who speak the Hmong-Mien languages are descended from the population that now speaks Austroasiatic Mon-Khmer languages.

This is particuarly notable because the speakers of the Munda languages are predominantly "tribal" peoples, and there has been a tendency to associate tribal peoples of South Asia with the most ancient layer of South Asia's population history.  But, while there may be an ancient South Asian substrate in linguistically Munda populations of South Asia that is particularly strong in the matrilineally inherited mtDNA of the Munda peoples and to a still strong extent in the autosomal DNA of these peoples, there is a clear Y-DNA and autosomal contribution from Southeast Aisa.

The Austro-Asiatic languages are believed to have expanded with agriculture and in particular with early rice farming agriculture, so its likely time of arrival can be associated with the earliest evidence for rice farming in South Asia. 

According to the Wikipedia account:
The earliest remains of the grain in the Indian subcontinent have been found in the Indo-Gangetic Plain and date from 7000–6000 BC though the earliest widely accepted date for cultivated rice is placed at around 3000–2500 BC with findings in regions belonging to the Indus Valley Civilization. Perennial wild rices still grow in Assam and Nepal. It seems to have appeared around 1400 BC in southern India after its domestication in the northern plains. It then spread to all the fertile alluvial plains watered by rivers.

The "tribal" character of the current populations probably reflects language shift among populations that continued to be sedentary rice farmers (mostly to either the Indo-Aryan languages, or to the Tibeto-Burman languages, although the genetic evidence suggests that most of the latter languages were transmitted mostly demically rather than via language shift, particularly on the Y-DNA side); and language conservation among populations that "reverted" to a hunting-gathering or pastoralist means of subsistance in areas that became unsuitable for rice farming.  The less sedentary populations were less easily subjegated by the Indo-Aryans.

As discussed below, this puts the arrival of the Munda languages in India earlier than the Indo-European languages (by 1000 to 1500 years), even earlier than the Tibet-Burman languages (by considerably more centuries), and roughly contemporaneously with the proto-language era of Dravidian immediately prior to its division into subfamilies.

The Indo-European Languages of South Asia

It is already widely agreed that the Indo-European languages of South Asia (mostly the Indo-Aryan languages, which are derived from Sanskrit, but also the Iranian languages and Nuristani languages found in Western Pakistan) are intrusiive to South Asia and arrived around 2000 BCE to 1500 BCE. 

Of course, the widely spoken Indo-European lingua franca of South Asia, which is English, is a legacy of colonial rule by the British, starting in the 1700s via the British East India Company and ending in 1947, when South Asia gained its independence from the United Kingdom.

The Tibeto-Burman Language Of South Asia

Genetic evidence, cultural evidence and historical evidence likewise point to the Tibeto-Burman languages spoken in South Asia's Northern and Eastern borders as intrusive more recently than either the Austro-Asiatic languages or the Indo-European languages.  And, thes languages are spoken only on the very fringe of South Asia, rather than penetrating deeply into it.

The Dravidian Languages

The case of the Dravidian languages is less settled.  With the exception of a pocket of Dravidan language speakers who speak the Brahui language of Pakistan, these languages are concentrated to the South and East of India.  Moreover, while the evidence of place names suggests that Dravidian languages were once spoken over a much wider geographic range in Southern India and the far Southeast of Pakistan than they are today (presumably displaced by Indo-Aryan languages ca. 1500 BCE in these places), per Wikipedia:

The Brahui, Kurukh and Malto have myths about external origins. The Kurukh have traditionally claimed to be from the Deccan Peninsula, more specifically Karnataka. The same tradition has existed of the Brahui. They call themselves immigrants. Many scholars hold this same view of the Brahui such as L. H. Horace Perera and M. Ratnasabapathy.   
Linguistic and genetic evidence, taken together, support an origin for Brahui sometime not long after 1000 CE, mostly via language shift rather than a demic migration of large numbers of Dravidian speakers from South Asia.

The 73 Dravidian languages are fairly closely related and there are attested versions of source languages for two of its main subfamilies by the 4th and 5th centuries respectively (Old Tamil ca. 300 BCE and Old Telegu ca. 400 BCE).  There was probably a single proto-Dravidian language that an ancestral to all modern Dravidian languages around 1500 BCE-2500 BCE.  This linguistically estimated dated coincides with the advent of farming in Southern India, an event known as the South Indian Neolithic

Thus, whether Dravidian was an indigeous language of Paleolithic South Indians, or was instead intrusive like India's other major languages, the particular Proto-Dravidian language that is ancestral to all of the modern Dravidian languages probably did not start to expand more than about a thousand years before the Indo-Aryans began to make their way into Southern India.

Autosomal genetics and most uniparental genetic markers point to ancestral South Indian genetic origins for the core of the linguistically Dravidian people (in some cases with an Indo-European demic infusion into the highest caste populations that underwent language shift) that is far, far older than the proto-Dravidian language. 

Any superstrate population associated with the Dravidian language must have been thin, and the only suggestive trace that I have identifed as a possible proto-Dravidian marker would be Y-DNA haplogroup T, which is most common in India geographically right where proto-Dravidian should have originated, although haplogroup T is now found in populations with various linguistic affiliations.  Y-DNA haplogroup T is found in appreciable frequencies among Somolians, Egyptians and Mesopotamians, and at low frequencies throughout the early Neolithic area, but isn't particular common in the Indus River Valley area where Y-DNA haplogroup T's sister clade, Y-DNA haplogroup L, is more common.

The linguistic origins of Dravidian are unclear.  Some of the more plausible linkages to Dravidian linguistically have been to the Elamite language, to the Uralic languages, and to the fringe members of the Niger-Congo linguistic family that show the simplifying impact of linguistic neighbors that speak languages from other language families.

The hypothesis that Proto-Dravidian was once the language of the Indus River Valley Civilization (mostly in modern Pakistan and the adjacent deserts of India which were once fertile river beds), has very little support in the modern distillation of the linguistic, genetic, and archaeological evidence.  The Indus River Valley civilization area and the Dravidian area are genetically distinct (the deep Ancestral North Indian v. Ancestral South Indian divide).  The archaeological evidence supports only a few border trading posts between the two civilizations.  There is no real evidence of a Dravidian substrate in the earliest Rig Vedic Sanskrit texts (Dravidian influence comes only later through word borrowing and areal influences).  And, the characteristic crops of the Dravidian linguistic area seem to be derived from Sahel African crops rather than from Fertile Crescent crops, as they are better adapted to the local seasons.  This is one of the reason that Fertile Crescent agriculture didn't immediately spread to South India once it arrived in the Indus River Valley area about four thousand years before the South Indian Neolithic.  There are cultural links in addition to crops to the culture of Sahel farmers.

This also tends to disfavor the Elamo-Dravidian theory of this language's origins, since that theory generally assumes that Dravidan reached India as an extension of the Harappan culture of the Indus River Valley which was, unlike South India, adjacent to Southern Iran where the Elamite language was spoken into the early historically attested era in the region.

Bottom Line

There are few tiny, near moribund possible exception of some language isolates in the Andaman Islands (which show genetic linkage to South India) and the highlands of the Himalayas, sometimes grouped into a conjectural and residual Indo-Pacific language family. 

But, otherwise, all of the languages of South Asia arrived there from outside South Asia within the last five thousand years or so, with the possible exception of one geographically tiny pre-Neolithic Dravidian language family dialect if that language is indigeneous rather than intrusive within the last ten thousand years or so.

The language of Paleolithic India as of about 8000 BCE are probably entirely lost, as is the Harappan language, unless one takes the minority view that proto-Indo-European was Harappan rather than the majority view that proto-Indo-European was a language of the Pontic-Caspian steppe.  The minority view is far less crazy than it is often decried as being, but still lacks the multidisciplinary evidnece to support it that the Kurgan hypothesis of Indo-European language origns does.

The main argument for Harappan as proto-Indo-European is the absence of any easily discernable substrate component to the early Sanskrit writings, against a presumed proto-Indo-European background validated with early West Eurasian languages and Tocharian.
But, this should not be misconstrued to say that the major languages of South Asia involved demographic replacement.  Genetically, South Asia's indigeneous Paleolithic peoples appear to be more strongly represented than almost anywhere else in the world, as evidenced by private Y-DNA lineages, private mtDNA lineages and the nature and distributions of South Asia's autosomal genetics in relation to those elsewhere in Asia and Europe.  The case the a majority of non-African modern humans lived in South Asia for much of the period from ca. 75,000 years ago until perhaps 30,000 years ago, is quite strong.  There are clear genetic superstate populations and there is no longer any pure ancestral South Indian population (the Andamanese probably come closest).  But, the ASI percentage of ancestry in much of India is quite high.

Friday, January 25, 2013

Muonic Hydrogen Size Still Smaller Than Expected

Muonic hydrogen protons still appear smaller than ordinary hydrogen protons.

In 2010, scientists published the results of an experiment showing that "the size of the proton (to be precise, its charge radius), measured in exotic hydrogen, in which the electron orbiting the nucleus is replaced by a negatively charged muon, yielded a value significantly smaller than the one from previous investigations of regular hydrogen or electron-proton-scattering. A new measurement published this year by the same team confirms the value of the electric charge radius" by a different method that is 1.7 times more precise than the previous measurement and that can ultimately be made even more precise. (The pre-print of the ultimate source is here).

The standard value of the electric charge proton radius determined from ordinary hydrogen was 0.862(12) fm, as of 1999 based on a 1980 measurement, about two and a half percent larger than the most recent measurement just announced for the electric charge proton radius in muonic hydrogen which is 0.84087(39) fm. 

While the measured magnetic radius is closer to the old ordinary hydrogen measurement, it is so imprecise that it is currently irrelevant to resolving the true size of the proton. "The new measurement also allows a determination of the magnetic radius of the proton for the first time by laser spectroscopy of muonic hydrogen. This results in a value of 0.87(6) femtometres, in agreement with all previous measurements."  The magnetic radius measurement, however, is sufficiently imprecise that it is consistent with both the old canonic ordinary hydrogen measurement and the new muonic hydrogen measurement - both results are less than half of a standard deviation away from the new magnetic radius measurment. 

The muon hydrogen experiment involved medium budget experiments as opposed to super-expensive experiments like the Large Hadron Collider that requires a cast of thousands of scientists and billions of dollars of hardware to conduct. 

This makes it a remarkable value because it is an independent tool that could point to possible beyond the Standard Model physics. 

Alternately, this experiment could confirm the Standard Model and dramatically increase the experimental accuracy of a constant that can be used to add precision to other QCD measurements such as the value of the strong force coupling constant. The strong force coupling constant is the least accurately known of the Standard Model coupling constants by many orders of magnitude (the uncertainty is about 0.6%) and the uncertainty in this experimentally measured constant accounts for a large share of the uncertainty, for example, in the theoretically predicted value of the proton mass from QCD first principles (which is about 1%).

What could explain the result?

Nothing in the Standard Model explains how a lepton orbiting a proton could change the size of the proton it orbits.

In the Standard Model, the orbits of both the electron and the muon around a single proton are governed exclusively by quantum electrodynamics, which has the most accurately determined theoretical calculations and most precisely determined experimental constants, and the electric charge radius of the proton.  Each of the relevant physical constants (other than the electric charge radius of the proton) is known to a one part per ten million accuracy or more.
Hydrogen consists of a single positively charged proton orbited by a negatively charged electron, a model whose success in explaining spectroscopy data dates back to its proposal by Bohr in 1913. The energy levels of this simplest of atoms can be predicted with excellent precision from the theory of quantum electrodynamics. However, the calculations have to take into account that -- in contrast to the point-like electron -- the proton is an extended object with a finite size, made of three quarks bound by so-call 'gluons'. Therefore, the electric charge as well as the magnetism of the proton is distributed over a certain volume. The extended nature of the proton causes a shift of the energy levels in hydrogen. Hence the electric and the magnetic charge radii can be deduced from a measurement of the level shifts. . . .
Muons behave a lot like electrons, except for their mass: muons are 200 times heavier than electrons. The atomic orbit of the muon is therefore much closer to the proton than the electron's orbit in a regular hydrogen atom. This results in a much larger sensitivity of the muon's energy level to the proton size and hence to a stronger shift of the energy levels.
So, what could be going on?  As the article linked above explains:
Physicists around the world are actively seeking a solution to the proton size puzzle. Previous measurements in regular hydrogen and by electron-proton-scattering are being reanalyzed and even repeated. Theorists of various disciplines suggested ways to explain the discrepancy. Very interesting proposals explain the discrepancies by physics beyond the standard model. Other explanations suggest a proton structure of higher complexity than assumed today which only reveals itself under the influence of the heavy muon.
According to the paper's authors the main possibilities that could cause the observed discrepencies are that:
* The electronic hydrogen experiments are almost, but not quite, as accurate as stated,
* The QED calculations are almost, but not quite, as accurate as stated,
* The two photon exchange term that depends on proton polarizability has not been correctly evaluated [this involves an intersection between QED and QCD effect: "The computer effect of this term is proportional to the lepton mass to the fourth power, and so is capable of being relevant for muonic atoms, but irrelevant for electronic atoms.], and/or
* The electron and muon really do have different interactions with the proton, so that there is physics beyond the Standard Model.

None of these possibilities seem very likely, but all must be pursued.
 
Any combination of the first three answers, of course, is boring, but collectively, those possibilities are much more likely than the last one.  The first two possiblities are entirely boring, the third is of interest only to true physics junkies, and the last could profoundly change the course of physics for decades to come.

Experimental Error In The Proton Radius Measured In Ordinary Hydrogen

One boring possibility is that measurements of the proton radius in an ordinary hydrogen atom are simply old, are far less precise than those with muonic hydrogen (something inherent in the lower mass of the electron), have understated error bars, and are slightly inaccurate.  If so, more accurately remeasured proton radius in ordinary hydrogen atoms conducted with state of the art modern equipment and QED calculations will match the muonic hydrogen result.

The central value of the canonical measurement of the electric charge radius of protons in ordinary hydrogen is 54 sigma different from the muonic hydrogen radius, a clearly inconsistent result.  But,  the central value of the muonic hydrogen based estimate of the proton radius is only about 1.75 sigma from the central value of the measurement made in 1980 which were still the best available as of 1999  (and even as of 2005).  Thus, the possibility that the difference is simply due to experimental error in the inherently less accurate measurement of the proton radius in ordinary hydrogen is very plausible. 

After all, the whole point of measuring the proton radius with muonic hydrogen was to get getter precision in this measurement relative to the ordinary hydrogen based measurement which was known to be not very precise.  Only no one had expected the ordinary hydrogen results to be so far off.

A review of the source data for the canonical ordinary hydrogen proton radius measurement in the new paper using the latest data available in 2013 from hydrogen spectroscopy, which includes eight new post-1980 data points developed from 2003 through 2011, states that:
From Fig. 2 one can observe that all rpvalues from H favor a larger rp around 0.88 fm. Still, half of the individual rp values agree with the muonic hydrogen value of 0.84 fm on the level of 1 sigma. In fact, only the 2S-8D5/2 transition disagrees with the muonic rp value on the level of 3 sigma. The discrepancy between the combined value from H, as obtained in the elaborate CODATA adjustment of the fundamental constants, and the muonic hydrogen value, is about 4.4 sigma.
The new paper summarizes also ordinary hydrogen proton radius estimates from another indepedent method (electron-proton scattering) from the results summarized in the blockquote above at:

rp = 0.879 fm +/- 0.005stat +/- 0.004syst +/- 0.002model +/- 0.004group,

adding up the errors in quadrature, the combined error estimate is about +/- 0.0078 fm, which is about 4.6 sigma away from the muonic hydrogen measurement.

There is currently one experiment in the works (scheduled for 2014-2015) to make a more precise measurement based on electron-proton scattering called Jefferson Lab E12-11-106, but it will have to be conducted with technical virtuosity just barely within the capabilities of the relevant equipment to produce a sufficiently precise result to improve on the results from the experiments done from 2003 to 2011.  Six new experiments are in progress to make more precision measurments of proton size in ordinary hydrogen using spectroscopy.

A muon-proton scattering experiment called MUSE at PSI is also in the works.  This experiment could be conducted by 2016 is the necessary $2 million of funding can be secured.

These two kinds of scattering experiments are particularly helpful in evaluating whether the proton polarizability term in the calculation of the proton electric charge radius from spectroscopy measurements have been correctly evaluated, thus, either implicating or ruling out on of the four most plausible explanations for the discrepency in proton size measurements between ordinary hydrogen and muonic hydrogen.

Spectroscopy experiments have also been contemplated with exotic synthetic "atoms" such as positronium (hydrogen atoms in which a positron is substituted for the proton), muonium (hydrogen atoms in which an anti-muon is substituted for the proton), muonic deuterium (heavy hydrogen atoms with muons instead of electrons rotating around them), muonic helium-3, and muonic helium-4, muonic lithium ions, muonic berylium ions, and muonic boron ions. Apparently, it is not feasible to conduct tests on tauonic hydrogen because taus (i.e. third generation electrons) are so short lived relative to muons.

Failure To Consider Material But Non-Obvious Factors In The Muonic Hydrogen Experiment 

Another boring possibility is that experimenters doing the theoretical calculations of the electric charge and magnetic charge radius in the muonic hydrogen experiments have overlooked a material adjustment that must be made, for example, for the electro-magnetic fields of neighboring muonic hydrogen atoms or special relativistic effects.

Similar issues gave rise to the only recently resolved Pioneer anomoly that showed an apparent discepency between the law of gravity and this space probe's actual course until adjustments for a previously unaccounted for factor related the thermal effects from the probe's power source were used to adjust the theoretically predicted trajectory.

Beyond The Standard Model Physics Explanations

But, any beyond the Standard Model physics that could emerge from this measurement would be entirely unexpected and point the way towards theoretical directions far removed from the vast majority of theoretical work in the last few decades.  It could, for example, be experimental evidence of quantum gravity effects, unexpected internal structure in quark-gluon model of the proton that could modify QCD, or even some previously unknown force. 

The biggest indicator that there could be non-Standard Model aspects to muon behavior is that the "experimental value of the muon anomalous magnetic moment exceeds the Standard Model expectation by more than three sigma." The discrepency between the theoretically predicted value of the muon anomalous magnetic moment and the experimentaly measured value is still only about one part per fifty million, however, and this could easily arise from something as subtle as some slight overconfidence in estimating margins of error. Data from tau physics experiments favor a smaller discrepency.  (More background discussion can be found here). 

At least five other sets of experimental data, in addition to the muon anomalous magnetic moment constrain modifications of the Standard Model that would given the muon properties other than mass that differ from those of an electron.

The 2013 paper discusses five ideas for beyond the Standard Model physics that could account for the results while not being inconsistent with the experimental data.  But, existing experimental data rule out "plain vanilla" forces mediated by bosons of spin 0 (scalar fields like that of the Higgs boson), spin 1 (vector fields like those of photons, W and Z bosons and gluons), or spin 2 (tensor fields like that of the hypothetical graviton) that couple to muons and nucleons but not to electrons, and which have equal couplings to muoons and to nucleons (both of which have the same electromagnetic charge).  Experimental data also rule out even more elaborate scalar fields.

Among the possible results would be a MeV mass force carrier that couples to both muons and nucleons but has different coupling constants for each.  A 30 MeV mass heavy photon that interacts with right handed neutrinos has been considered but is highly constrained (i.e. basically disfavored) by current experimental results.  Another set of models looks at two extra force carrier particles that are quite different in kind from one another - one that gives rise to an effect even bigger than the anomalous results observed and another which suppresses these effects in circumstances other than the ones in which the anomalous effects are observed.  Yet another possibility is a very short range force that modifies electromagnetic interactions (i.e. Coulomb forces) at short ranges where muons orbit, but not at longer ranges where electrons orbit.

Bottom Line

By far the mostly likely possibility is that the temptest in a teapot within the physics commuity over the different measured sizes of the proton in ordinary hydrogen and in muonic hydrogen respectively, will be resolved by finding in a more careful analysis that physicists measuring the quantity in ordinary hydrogen were overconfident in their estimates and calculations, or made a slight miscalculation of one difficult to evaluate term in their calculation.

But, since this data point and another one related to muons presents a possibility that it could reveal new physics at a tiny fraction of the cost of LHC experiments which currently seem far less likely to do so, this issues deserves the funding necessary to answer the question.

Tuesday, January 22, 2013

How Precisely Are Fundamental Constants Known?

A brief summary of how accurately we have measured the fundamental physical constants that make up the laws of nature (i.e. the Standard Model, General Relativity, and a couple of constants from cosmology) is set forth below.  It omits constants that have a value that is fixed theoretically to an exact number determinable without experiment in those models (e.g. the zero rest mass of a photon or the number of types of gluons or the number of generations of fermions or the charges and weak isospins of the fundamental particles).  Experiments have essentially ruled out models that do not have exactly three generations of fermions and exactly three QCD colors.

Neutrino physics

Some of the greatest uncertainies regarding fundamental constants in the Standard Model involve neutrino physics because neutrinos are very difficult to measure directly.

Two key experimentally measured constants in the Standard Model: the hierarchy of the three neutrino mass eigenvalues ("ordinary" or "inverted") and the CP violating parameter of the PMNS matrix that governs neutrino oscillations are not known at all (although its other three parameters have been estimated to meaningful accuracy, as discused below).

There is a roughly 400% uncertainty regarding the absolute masses of the neutrinos (the sum of the three mass eigenvalues cannot be more than about 0.3 eV, but the difference in mass between the lightest mass eigenvalue and the heaviest puts a minimum value of the sum of the three masses at about 0.07 eV).  This could be cut in half over the next several years to a decade by experiments currently under way.

PMNS matrix angle theta13 has an experimentally measured value with an uncertainty of about 13%.  The mass difference between the second and third mass eigenvalues for neutrinos and theta23 have uncertainties of about 5%. Theta 12 and the mass difference between the first and second neutrino mass eigenvalues have uncertainties of about 3%.

Another uncertainties in neutrino physics in the Standard Model, are whether neutrinos are Dirac or Majorana in nature (if they are Majorana in nature, they give rise to two more unknown Standard Model constants for Majorana neutrino related CP violations).

Neutrinos, and in particular, neutrinoless double beta decay rates, are critical parts of models with lepton number violations and with Majorana neutrinos.  This has not been discovered to date.

Substantial progress in pinning down all of these constants is anticipated over the next several years to a decade or so due to the concerted efforts of multiple active experiments investigating these matters.

QCD constants

A number of experimentally measured strong force physics, i.e. quantum chromodynamics (QCD) constants are also know with a fair amount of uncertainty.  The masses of the quarks are known with the amounts of uncertainty shown parenthetically after each one (the maximal number if the uncertainty around the preferred value is asymmetrical): u (30%), d (15%), s (5%), c (2%), b (0.7%), t (0.5%).

Despite the uncertainty in the indirectly measured u and d quark masses (which are always "confined"), the mass of the proton and neutron made entirely of these quarks and gluons are known with great precision, as are the masses of most unstable mesons and hadrons made up only of up and down quarks.

The coupling constant is the strong force coupling constant known to about 0.6% accuracy.   

In the big picture, this means that QCD calculations (i.e strong force physics) are accurate to predict many observables (e.g. proton mass) to only about a 1% precision, making first principles calculations far less accurate than direct experimental measurements in almost all cases.

There are some questions relating to the infrared behavior of the the strong force (i.e., is there a "non-trivial" infrared fixed point and if so, what is  it)?

It is theoretically possible, without doing great injustice to the Standard Model, for there to be a CP violating constant in the strong force equations, although the current efforts to measure this are consistent with zero and the Standard Model assumes that it is zero.

Improvements in the measurement of these constants is likely to be incremental and more gradual than in neutrino physics, in part, because of the amount of progress that has been made to date.  The measurements in these fields are more mature and much of the problem relates to developing accurate theoretical models of complex systems that are actually measured in order to make comparisons between theoretical predictions and experimentally measured values possible.  Since quarks make up a quite small portion of the mass of mesons and hadrons (since most of the mass is attributable to the gluon activity that binds the quarks), theoretical predictions have to be very precise to translate these measurements into particle mass measurements.

Extensions of Koide's formula allow for estimates with precision on the order of the electroweak masses described below, but the lack of experimental precision makes these formulas difficult to verify experimentally.  Also, some of these extensions seem to contradict the admittedly only marginally precise data that we have in hand to date for up and down quarks without further modification.

Electroweak constants (apart from neutrino physics)

The measured values of the CKM matrix mixing angles:

θ12 = 13.04±0.05°, θ13 = 0.201±0.011°, θ23 = 2.38±0.06°, and δ13 = 1.20±0.08.

The uncertainties, expressed on a percentage basis, in each respectively are to one significant digit: 0.4%, 5%, 3%, and 8%.  The need to have consistency with an overall fit which is experimentally confirmed so far, also makes the whole somewhat less malliable than individual measurements of these constants by themselves, so the uncertainties of modestly overstated.

This Higgs boson mass is known to a certainty on the order of 2% and the vaccum expectation value of the Higgs field is known to a certainty on the order of 0.5%.  The W boson mass is known to a precision of about 0.02%.  The Z boson mass is known to a precision of about 0.002%.

The electron mass is known to a seven significant digit accuracy.  The muon mass is known to a nine significant digit accuracy.  The tau mass is known to a five significant digit accuracy.

The electromagnetic coupling constant is known to a ten significant digit accuracy.  The weak force coupling constant is known to an eight significant digit accuracy.

The only electroweak physics left to refine are some modest improvements in the accuracy of the CKM mixing matrix angles that the LHC is facilitating as a side project, and increased confirmation of the Higgs boson mass and that its properties match those of the Standard Model Higgs boson (which so far have been satisfied in multiple respects to the limits of current experimental accuracy).

General relativity and cosmology constants

The speed of light in a vacuum is known to an accuracy of roughly nine significant digits.  Planck's constant is known to an accuracy of about seven significant digits.  The accuracy of Einstein's law of special relativity has been tested to accuracies comparable to those of the speed of light and the electroweak constants.

The gravitational constant is known to an accuracy of about one part per thousand. The cosmological constant in the equations of general relativity is known to only a roughly one order of magnitude precision: it is roughly 10−52 m−2.  The Hubble constant and estimated age of the universe are known to a precision of about 1%.

Various deviations of general relativity from simple Newtonian gravity have been measured experimentally and found to match the predictions of General Relativity to precisions of one part per thousand to one part per ten thousand in most cases (e.g. the precession of the perihelion of Mercury's orbit, the deflection of light by the sun, the gravitational redshift of light, graviational lensing, light time travel delay, frame dragging, equivalence principal, binary pulsar behavior in strong fields including apparent gravitational waves).

Dark Matter and quantum gravity

Of course, the big unknown in astronomy, cosmology and gravitational physics is the question of dark matter about which there is no single consensus explanation for their mechanism.  For example, there is no identified dark matter particle.  The effects attributable to dark matter have been measured to precisions on the order of about 1%, but the details of their cause isn't known and more experiments seem to be creating more questions rather than more certainty.

Dark matter phenomena are definitely the greatest "known unknown" of physics.  WMAP data fit dark matter cosmology models involving cold dark matter and a cosmological constant, and allow, but disfavor, up to one kind of light dark matter particle (although other sources of data pretty much definitively rule out another generation of neutrino as that particle). 

Particle physics experiments and direct dark matter detection experiments have largely ruled out a large mass range of weakly interacting dark matter particle candidates. 

The single constant in the empirical MOND model which quite accurately models essentially all galactric rotation curves observed by astronomers (regardless of the accuracy of the mechanism it implicitly assumes which is a modification to the law of gravity in weak fields rather than a dark matter particle) is known to an accuracy of about one signficiant digit.  Different dark matter models have several constants each that are fitted to experimental data.

Searches for quantum gravity distinctions from general relativity has focused on black hole event horizons, implications for cosmological models, implications for the large scale structure of the universe, cosmic ray behavior, WMAP cosmic background radiation measurements, and weak field behaviors that could lead to phenomena equivalent to dark matter and dark energy (at least in part).  Limited efforts have also been underway to measure gravitational effects at the sub-centimeter level which are difficult because gravity is so weak relative to other forces that could be relevant at such short distances.  Some of the very subtle predictions of general relativity are very difficult to measure with human scale experimental resources.  In understanding this difficulty consider, for example, that the entire planet Earth, for example, radiates about only about 200 watts of gravitational radiation

Theoretical considerations involved in harmonizing the Standard Model and General Relativity play a larger role than astronomoy observations in current efforts to develop theories of quantum gravity at the moment.  The tricky part at this point is to devise ways to experimentally test possible variants on General Relativity.

Limitations on beyond the Standard Model physics

All experimental results to date are consistent with the Standard Model.

A few alternatives to the Standard Model are admitted by experiment, but are highly constrained experimentally at "low energies" (up to about 100 GeV-10 TeV), which a low relative to hypothetical maximal energy scales such a "grand unification" energies and the Planck scale, but exceed the energy scales seen in all but the most extreme processes (mostly not too long after the Big Bang) in nature.

At the currently established mass of the Higgs boson, the Standard Model is mathematically coherent up to roughly the Planck scale, something that would not have been the case at many other Higgs boson masses.  So, beyond the Standard Model physics isn't strictly necessary for it to function even at very high energies, even if it is an "ugly" model that leaves the "why" questions behind many of its features unexplained.

Strict experimental bounds on lepton number violations, neutrinoless double beta decay, flavor changing neutral currents, proton decay, non-Standard Model particle decays, and minimum masses of hypothetical particles with particular properties greatly constrain these models, as does the discovery of the Higgs boson.  Simpler supersymmetry models (including string theories), technicolor models, and extradimensional models, for example have well established experimental limitations placed upon them.  Strict boundaries have been established on the constancy of a number of key fundamental physical laws and constants over billions and billions of years as well.

Any modification to the Standard Model must, essentially, add moving parts to a minimal Standard Model but retain much of its overall structure and manifest only in extreme conditions.  Supersymmetry models, for example, have more particles than the Standard Model, but those particles all behave according to rules very similar to those governing the behavior of Standard Model particles.

9 Year WMAP Data Favors Three Neutrino Species

The cosmic background radiation of the universe is measured by an experiment called WMAP which has just published its ninth year of data.  The big news is that it completely consistent with the three generations of neutrinos in the Standard Model of Particle Physics (within about two-thirds of a single standard deviation), and is inconsistent at a roughly 4.97 sigma level (roughly the threshold for scientific discovery in particle physics) with more than one weakly interacting light non-Standard Model particle (e.g. with more than one species of sterile neutrino).

[C]ompared to the 7-years WMAP data, the update typically brings a 20-30% reduction of already tiny errors on the composition of the Universe. There is however one number that changed visibly. The effective number of relativistic degrees of freedom at the time of CMB decoupling, the so-called Neff parameter, is now Neff = 3.26 ± 0.35, compared to Neff = 4.34 ± 0.87 quoted in the 7-years analysis. For the fans and groupies of this observable it was like finding a lump of coal under the christmas tree...  
So, what is this mysterious Neff parameter? According to the standard cosmological model, at the temperatures above 10 000 Kelvin the energy density of the universe was dominated by a plasma made of neutrinos (40%) and photons (60%). The photons today make the CMB about which we know everything. The neutrinos should also be around, but for the moment we cannot study them directly. However we can indirectly infer their presence in the early universe via other observables. First of all, the neutrinos affect the energy density stored in radiation:
which controls the expansion of the Universe during the epoch of radiation domination. The standard model predicts Neff equal to the number of known neutrinos species, that is Neff = 3 (in reality 3.05, due to finite temperature and decoupling effects). Thus, by measuring how quickly the early Universe was expanding, we can determine Neff. If we find Neff ≈ 3 we confirm the standard model and close the store. On the other hand, if we measured that Neff is significantly larger than 3, that would mean a discovery of additional light degrees of freedom in the early plasma that are unaccounted for in the standard model. Note that these new hypothetical particles don't have to be similar to neutrinos, in particular they could be bosons, and/or have a different temperature (in which case they would correspond to non-integer increase of Neff ). All that is required from them is that they are weakly interacting and light enough to be relativistic at the time of CMB decoupling [ed. about 1 MeV in mass or less]. 
The irony is rich. 

On one hand, the results of the nine year data are a very good fit to the lambda cold dark matter model tuned to fit the previous 7 year WMAP data release. 

On the other hand, the WMAP data have ruled out the possibility that there is more than one species of cold dark matter particle and a model with no weakly interacting light particles beyond the Standard Model is disfavored over a model with only Standard Model particles by a ratio of about 4-1, although they aren't entirely excluded.

Data from other sources are consistent with a Neff (effective number of neutrino species) of 3-5.  Collider data (such as LEP) strongly support just three neutrino generations and so do neurino oscillation measurement, which just a year or two ago might have supported four or five kinds of neutrinos.

UPDATE of February 6, 2013: Corrected data largely supersede the results above as discuss here.

Monday, January 21, 2013

Was Hades Permanent?

I have been reading James D. Tabor's new book "Paul and Jesus" (2012), and have blogged about its relevance to Christian theology and the modern culture wars at my Wash Park Prophet blog. 

But, one notable observation in the book has relevance to the Indo-European origins of the Greeks and also of the Hindus, so this data point finds its way here.

The Context Of Tabor's Observations

Tabor, a career intellectual historian of Christian origins, and he addresses this in the context of how Saint Paul, whose letters and journey are central to the Christian New Testament, viewed and talked about the afterlife, a task that required him to reconcile a Jewish conception with the prevailing Hellenic conception.  His main object in doing so is to understand what the resurrection of Christ meant to early Christians and early members of the Jesus movement within Judaism that would ultimately wither while Christianity ultimately became the dominant religion of Europe.

Greek views, in particular, were relevant, because Paul's evangelism was centered in the Greek speaking Aegean basin and in then Greek speaking Southern Anatolia and Syria, although he is reputed to have traveled as far west as Spain and as far South  as Mount Sinai.  Politically, the entire region was under Roman control at the time.

In doing so, Tabor makes some very interesting observations about pre-Christian Greek understandings of the afterlife in the time period leading up to the Christian era.  His description is based in part, of course, on some of the older accounts of classical Greek philosophers like Plato, since contemporary Greek sources on this metaphysical question are limited.

Plato's Context

Plato's writing post-date by about a two thousand to fifteen hundred years (depending upon where in the Aegean basin you are talking about) the transition from non-Indo-European pre-Greek languages to Indo-European ancient Greek.  [Note that for the purposes of this post, it doesn't matter if that transition was demic or cultural, since I am tracing a cultural and metaphysical worldview legacy that could easily have accompanied the language shift without regard to the extent that it was demic in character, which is fortunate, because that issue isn't a definitively settled one.]

Plato was about as far removed from the earliest Indo-European Greek language speakers as we are from the early Christian church prior to the fall of Rome.  Thus, it is fair to assume that the foundational worldview conceptions of the early ancient Greek speakers may have persisted to Plato's time, just as early Christian worldviews remain familiar in the 21st century.

Tabor on Greek Afterlife Beliefs via Plato, et al. as Hindu-Like

Tabor argues that in the Greek conception there was an immortal soul which temporarily resided in an impermanent earthly body, and that at death, the immortal soul (but not the earthly body) returned to a Chthonic Hades. 

So far, a basically familiar understanding.

Far more notably, however, Tabor argues that the Greeks did not see the soul's trip to Hades as a one way journey.  In his account, the prevailing Greek view was that immortal souls in Hades would often return to a new body on Earth to develop further, in a worldview very similar to that of the Vedic Hindus, another major branch of Indo-Europeans.

Reincarnation, of course, has remained a part of the South Asian religious worldview and was adopted not just by Hinduism, but by Buddhism, which unlike Hinduism expanded far beyond South Asia to become a dominant element of Eastern religious thinking.

In Tabor's account, the notion of death as at least a one way journey, with exceptions for extremely rare near death experience revivals and for a possible Resurrection in a new spiritual body in the end times, has its source in modern Western religious metaphysical thinking in Christianity under formulas worked out in the first instance by Saint Paul. 

Tabor doesn't expressly make the connection between Greek reincarnation belief and Hindu religious views, as they would be detours from the points his is trying to prove.  But, the similarities are patent and obvious to anyone reading his prose on the subject.

The notion that the trip to Hades is a one way trip, in modern readings of Greco-Roman mythology, then, is merely an unconscious and anachronistic imposition of thoroughly assimilated Christian metaphysical understandings on these myths that would not have been shared by the people for whom they were a living set of religious beliefs.

Given that this is the first time I have ever heard of reincarnation as a central afterlife belief of the ancient Greeks, and Tabor's somewhat controversial status in his field, I am not entirely convinced by his isolated account that this is an accurate description of Hellenic beliefs.  It is not, for example, reflected in this account at the Metropolitan Museum of Art in New York City.  It is also not clear in this scholarly account drawing on the writings of Homer and Virgil.  But, Tabor is sufficiently credible that the idea with deep implications, discussed below, deserves more careful examination.  According to this account:
The notion that the human soul enters another body upon death, though unfamiliar in popular Greek religion, was widespread in Greek philosophy. The doctrine of transmigration is first associated with the Pythagoreans and Orphics and was later taught by Plato (Phaedo, Republic) and Pindar (Olympian). For the former groups, the soul retained its identity throughout its reincarnations; Plato indicated that souls do not remember their previous experiences. Although Herodotus claims that the Greeks learned this idea from Egypt, most scholars do not believe it came either from Egypt or from India, but developed independently.
Of course, scholars may not have considered the notion that the Greeks derived this idea not from India but from Proto-Indo-Europeans ancestral to the Greeks and the people of India alike, and it could be that Greek philosophy, rather than Greek religion, was the more conservative medium.  Greek abandonment of reincarnation ideas in more popular culture could have arisen from the borrowing of ideas by this sea faring peoples from the Levatine Semitic neighbors.

Favoring an Indo-European culture that included reincarnation belief is this scholarly source suggesting that the Norse had similar reincarnation beliefs to the Greeks.

Implications For The Proto-Indo-European Culture

It is widely assumed that the polytheistic religious views of Indo-Europeans generally have some proto-Indo-European roots, albeit incorporating local substrates and adapting to local conditions.

But, until hearing Tabor's account, the reincarnation concepts that figure so prominently in Hinduism had seemed like a local innovation or substrate influence, rather than part of the Indo-European cultural package.  Tabor's observations, if accurate, suggest that this is not the case, and the reincarnation of the soul is an element of the Indo-European cultural package that was conserved in India, but was lost in other parts of West Eurasia as a result of Semitic religious influences.

This, in turn, adds serious substance to our cultural understanding to the Proto-Indo-Europeans who bridge the cultural gap between the Western Indo-European cultures like the Greeks, and the Eastern ones, like the Vedic culture that gave rise to Hinduism and Sanskrit.

Wednesday, January 16, 2013

What Part of Fundamental Physics Must Give?

[There] is a deep conflict between fundamental physical principles, that form the foundation of our most basic framework for describing physics. These pillars are quantum mechanics, the principles of relativity (special or general), and locality. These pillars underly local quantum field theory, which serves as the basis for our description of physical reality—from the shining sun to creation of matter in the early Universe to the Higgs boson (if that's what it is).
These principles clash when pushed to the extreme—the sharpest version of the problem arises when we collide two particles at sufficient energy to form a black hole. Here, we encounter the famed black hole information problem: if the incoming particles start in a pure quantum state, Hawking's calculation predicts that the black hole evaporates into a mixed, thermal-like final state, with a massive loss of quantum information. This would violate—and thus doom—quantum mechanics
While serious people still consider modifying quantum mechanics, so far proposals to do so create much bigger problems. . . . Quantum mechanics appears to be remarkably resistant to sensible modification. If quantum mechanics is sacred, apparently other principles must go: either those of relativistic invariance, or of locality, or both. The former likewise appears resistant to sensible modifications, but locality is a remarkably "soft" principle, in the context of a theory with quantum mechanics and gravity. So, that seems a reasonable concept to suspect.
The basic statement of locality is that quantum information cannot propagate faster than the speed of light. At least as early as 1992, modification of locality to solve the problem of getting missing quantum information out of a black hole was proposed. . . . In a context where one or more supposed bedrock principles must be discarded, we obviously need to be a little crazy—but not too crazy! . . .
Suffice it to say: while it appears that one of three basic pillars of physics must be modified, and that locality is the prime suspect, modification of locality is no small matter. Naive modifications of locality—as often proposed by physicists "on the fringe," generically lead to disastrous collapse of the entire framework of quantum field theory, which not only has been experimentally tested to a very high degree of accuracy, but underlies our entire physical picture of the world. If such modification must be made, it must be subtle indeed. It also appears that the basic picture of reality as underlain by the fabric of space and time may well be doomed. What could replace it is a framework where the mathematical structure of quantum mechanics comes to the fore. I would say more … but marching orders.
I will say I am deeply concerned about how we will arrive at a complete and consistent theory of gravity, and that we must, in order to describe not only black holes—which have been found to be ubiquitous in the universe—but also both the early inflationary and pre-inflationary evolution of our universe, as well as our seemingly dark-energy dominated future. The current problems at the foundations link to multiple big questions—and I fear it will be no small feat to resolve them.
From the answer of UC Santa Barbara physicist Steve Giddings to the 2013 "Edge" question, "What *Should* We Be Worried About?", entitled Crisis At The Foundations of Physics.

Another pillar of fundamental physics that is closely related to and intimately intertwined with locality is the notion of causality.

The Example of Quantum Entanglement

A useful illustration of this concept is the phenomena known as quantum entanglement (the drawing below is mine and not copied from another source).




When two quantum particles become "entangled" at a particular point in time and space (A), and then separate from each other at different points in time and space (B) and (C), their behavior remains correlated with each other.

Individually, a particular quantum mechanical property of (B) is entirely random and cannot be known until it is measured. But, if you measure that property in (B) you can know to a certainty that its entangled partner, (C), will take a value of that property that is complementary to (B).

So, if we measure (B) to be + then (C) will be - no matter when we actually measure (B) and (C). For example, even if we measure (B) and (C) at precisely the same time and they are separated by a ten light years at that point, and the +/- value of (B) and (C) are indeterminate at that point, when our experimenters eventually compare their measurements, if we measured (B) to be +, we will have measured (C) to be minus (-).

That this is true is a matter of indisputable empirically proven scientific fact, and it is implicit in the equations of quantum mechanics (both in the Standard Model and in all non-crackpot variants of it).  But, why this is possible or how this comes to be is an open question.  Some physicists under the slogan "shut up and calculate" are content to know this is true without a fundamental mechanism and doubt that the question of "how" is anything other than a category error. 

But, lots of very respectable physicists and natural philosophers do ponder this question.

Alternative Explanations For Entanglement

There are three basic ways (at least) that this empirical reality can be resolved.

1.  Lee Smolin, a physicists best known for his loop quantum gravity work, offers one of them in his Edge question answer, "hidden variables."

In other words, through a theory deeper than the stochastic quantum mechanical theory that we use today, a deterministic law has resolved the question of whether each particular particle will be a + or a - when measured, even though it appears to be underdetermined to us when we observe it.

He is in good company with Einstein, de Broglie, Schroedinger, and Bohm, all of whom have stated that they believed this to be the case at some point.

But, "hidden variables" theories are strongly disfavored by the physics community at this point because a variety of experiments designed to reveal more naiive hidden variables have failed to find them.  Bohm, the last of these titans of physics to weigh in on the question formulated his hidden variables interpretation of quantum mechanics in the 1950s.  The "Copenhagen interpretation" as it is called, which disavows hidden variables, rather than Bohmian quantum mechanics, is overwhelmingly the mainstream view of practicing physicists today.

2.  A second solution is non-locality. The value of the quantum property truly is undetermined until (B) or (C) is measured, whichever happens first,[1] but, when this happens, this is communicated instantly, rather than merely at the speed of light, from one particle to the other. The term "quantum teleportation" implicitly adopts this understanding.  As Professor Giddings explains, there are multiple ways that a non-locality proposition could be implemented. I will offer here several of my own examples (rather than his examples which are a bit obscure to people not familiar with recent debates about black hole "firewalls"):

* The information truly "teleports" from (B) to (C) without passing through intermediate points (i.e. there is no speed of light limitation on information); or

* Space-time is fundamentally made up of a discrete grid of nodes with perhaps four connections each. While, on average, these nodes are arranged in a fairly smooth adjacent pattern that emergently gives rise to four dimensional space-time, nothing prevents one node from being directly connected to another node that is far from the first node in classical space-time based on its other three connections (this is true in most loop quantum gravity theories); or

* Space-time as we know it is a four dimensional space embedded in a larger eleven dimensional universe, and certain kinds of quantum information can take shortcuts through one or more of the other seven dimensions, even though no known fundamental particles themselves (except perhaps the hypothetical graviton) can do so (this is true in many version of string theory).

[1] One reason to be skeptical of non-locality is that the phrase "whichever happens first" is inherently ambiguous in the context of general relativity because time passes at different rates for different observers.  There are definitional ways of resolving this ambiguity, but they aren't very elegant.

3.  A third solution is backward causality. Assuming (without loss of generality) that (B) is measured first, a message goes backward in time from (B) to the point of entanglement (A) at the speed of light or some slower speed, and then goes forward in time to (C).

Importantly, because it illustrates the deep connections between locality and causality, backward causality is equivalent to stating that non-locality for quantum information is possible for entangled particles, but only within the light cone of the point of entanglement.

Which approach makes the most sense?

The trouble is that messing with any of the pillars of fundamental physics: an absence of hidden variables, locality, or causality, raise all sorts of difficult and troubling issues if not bounded in some exquisitely constrained way.

Each approach is appealing in its own way.

I tend to favor either a hidden variables or causality violation interpretation over a non-locality interpretation for the reason I state in my footnote [1].   But, I'm not at all certain that interpretations aren't all mathematically and physically equivalent.  Also, I recognize my personal biases strongly influence how I weigh the possibilities. This is a situation where it is not at all clear which way Occam's Razor points.

Tuesday, January 15, 2013

SUSY Higgs Boson Global Fits Get Specific

In there Standard Model there are 4-3 Higgs bosons (ie. one of them because the other three are "eaten" by the W+, W- and Z bosons).  But, in Supersymmetric models there are at least 8-3 Higgs bosons (i.e. five of them), two charged and three neutral (some supersymmetric models have additional sets of four Higgs bosons).
[I]f you believe in Supersymmetry you might want to try and classify the newly found boson . . . as one of the three neutral states that the less complicated class of SUSY theories predict to exist: two h, H cp-even states, and a CP-odd state A. Or some mixture of those. If you do that, you immediately get some constraining power to add to the many direct searches for SUSY signatures in the tan(β) versus M_A plane. The exercise may thus reveal where to look for the other Higgs bosons, for instance! . . .
So, a new paper by Bechtle, Brein, Heinemeyer, Stal, Stefaniak, Weiglein and Williams . . .  [has] taken information about experimental rates and limits of neutral Higgs decays in all measured final states by the experiments at the LHC and Tevatron, together with limits from charged Higgs signals, and produced a map of delta-chi squared (a statistical measure of compatibility between experimental results and theoretical predictions) in the tan(β) - A mass plane. . .
In particular, by assuming that the 126-GeV Higgs boson is the heavier of the two neutral CP-even states, then the best-fit region highlighted in black shows that, if one accepts the authors' sample choice of some of the SUSY parameters (except β and M_A), [specifically: MSUSY = 1 TeV; |X|= 2.4 TeV; mu = 1 TeV; M1 = 100 GeV; M2 = 200 GeV; M3 = 800 GeV] one gets the hint that the A mass is 101 GeV, tan(β) is 6, and the light-Higgs h mass is 92.3 GeV. . . . in this scenario the h particle, the lightest Higgs, escapes the LEP II search limits by acquiring reduced couplings to Z bosons (I recall that LEP II limits a standard model Higgs at 114.4 GeV, but that if one assumes that the production cross section of h in electron-positron collisions is smaller than what the standard model calculates, then LEP II could have missed that particle). . . we are down to ranges of tan(β) from 2 to 14.
From here.

This has the desirable character of being falsifiable with existing technologies and there are indeed rumors of a possible 100 GeVish bump in the LHC data.  The margin of theoretical error in the mass predictions is roughly +/- 2.5 GeV at the one sigma level.

But, this narrowed parameter space isn't too meaningful because less complicated versions of SUSY used to make the estimate, the Minimal Supersymmetric Model (MSSM), and even its close cousin, the next-to-MSSM (NMSSM) is increasingly being ruled out on a variety of grounds in addition to those provided by a Higgs boson mass fit in any case.  A computer program linked to in the paper allows for others to make their own fits with different choices of parameters from the same data.
 

Monday, January 14, 2013

Friday, January 11, 2013

More Hobbit Fossils Confirm Existence Of Species

Newly reported research on  Homo floresiensis confirms that these Hominin skeletal remains from the Indonesian island of Flores really do represent a distinct species or subspecies of hominins, rather than diseased individual Homo sapiens.  Basically, the new research confirms the prior research in Flores.

The Hobbits Were A Distinct Species Of Small Hominins.

According to lead author Caley Orr:
The tiny people from Flores were not simply diseased modern humans. . .  The new species of human stood approximately 3' 6" tall, giving it its nickname "The Hobbit" . . . [T]hey walked on two legs, had small canine teeth, and lived what appears to have been an iconic "cave man'" lifestyle. Stone tools and evidence of fire use were found in the cave, along with the remains of butchered animals, such as Stegodon (an extinct elephant relative), indicating that meat was a part of diet.
But, there were differences from modern human as well:
The Hobbits had arms that were longer than their legs, giving them a slightly more ape-like structure. Their skulls had no bony chins, so their faces had more of an oval shape. Their forehead was sloping. The inferred brain size was tiny, putting them in the IQ range of chimpanzees.  . . . the feet were also long relative to the legs.
According to anthropologist Tracy Kivell:
These fossils provide further, clear evidence that H. floresiensis is in no way a pathological modern human, or that its primitive morphology is related simply to its small body size. Instead, it is clearly its own, unique and very intriguing species. . . .  
What is particularly interesting is that H. floresiensis is associated with such a long, well-documented history of stone tools. (Its primitive hand and wrist were) still apparently capable of making and using stone tools, suggesting that H. floresiensis solved the morphological and manipulative demands of tool-making and tool-use in a different way than Neanderthals and ourselves.
Is Denisovan Admixture In Modern Humans Really Hobbit Admixture?

So, where does Homo floresiensis fit in the hominin evolutionary tree?
The Hobbit's wrist looked like that of early human relatives, such as Australopithecus, but the key ancestral candidate now is Homo erectus, "Upright Man." It is possible that a population of H. erectus became stranded on the Indonesian island and dwarfed there over time. Orr said that "sometimes happens to larger animals that adapt to small island environments." A problem, however, is that H. erectus is somewhat more modern looking than the Hobbit, so researchers are still seeking more clues.
And, what role did they play in the prehistory of modern humans?
Another question concerns whether or not the Hobbits ever mated with modern humans. . . . So far, however, conditions have not been right to extract DNA from H. floresiensis bones.
The Geography Of Flores Fits The Modern Population Genetic Boundaries Of Denisovan Admixture



The island of Flores is very close to the Wallace line (the biogeographic barrier between areas once connected by land to mainland Asia and those that were not for a hundred million years or so). This is also the point at which modern humans whose genomes have archaic admixture corresponding the ancient DNA from the Denisova cave in Siberia (basically Aboriginal Australians and Papuans and peoples admixed with those populations).


Hobbits And Modern Humans Co-Existed For 32,000 Years

Homo floresiensis related artifacts start to appear around 95,000 years ago on the island of Flores.  Modern humans reached the island of Flores around 45,000 years ago.

There is evidence that Homo sapiens and Homo floresiensis probably co-existed on the island of Flores for many thousands of years, and as recently as 17,000 years ago by conservative estimates, and more likely until at least until 13,000 year ago.  This is roughly 32,000 years after the founding populations of Australia and Papua New Guinea's indigenous populations cross through Flores en route to their final destinations.

In contrast, periods of co-existence between Neanderthals and modern human populations in geographic regions that small, or between modern human hunter-gatherer populations and first farmer populations in geographic regions that small, where we have accurate archaeological evidence, appear to have typically lasted no more than 1,000 years in any one place.  There are no archaeological examples of mixed Neanderthal-modern human communities.

Neanderthals and modern human hunter-gatherers co-existed in Europe for about 21,000 years, and in the Levant for perhaps 25,000 years or so, but for the most part, they did not exist so close to each other in any one place for anything close to that long of a time period.  Europe is a much bigger place than the island of Flores.

Of coure, early divergence of Australian and Papuan populations (the Philippine Negrito group called the Mamanwa people also probably had common origins with these two population and diverged around the same time) strongly suggests that admixture that survived into populations in existence today happened during the first few thousand years (or less) of that co-existence.  But, the long period of co-existence points to a stable and cooperative form of co-existence, something that local legends on the island of Flores (discussed below) also support.

There Are Plausible Reasons For Modern Human Interactions With Hobbits To Be More Peaceful Than Those With Homo Erectus.

One plausible possibility is that a stable symbiotic relationship developed between Homo floresiensis and modern humans, but not between Homo erectus and modern humans, because the small and childlike Homo floresiensis seemed less threatening to modern humans.

Also, the difficulty involved in crossing the straight to reach the island of Flores may have kept the initial modern human population of the island whose first contact experience set the tone for future interactions small enough that it did not overwhelm the Hobbits.  In contrast, when archaic hominins on the mainland encountered wandering modern human tribes, the modern humans may have so dramatically outnumbered the archaic hominins that defeating them or routing them from their traditional homes may have been so easy that there was no incentive to develop interacts that didn't lead to archaic hominin extinction.

If the modern human population that admixed with  Homo floresiensis was small, this would also make it possible for a very small number of admixture events to account for the inferred nearly 8% initial modern human-Denisovan admixture level that modern population genetic studies suggest was present via founder effects.

There Are Few Other Plausible Sources Of Denisovan Admixture In Modern Humans

In contrast, there is no archaeological or population genetic evidence for prolonged period of co-existence between Homo sapiens and Homo erectus proper (one of the type fossils for which is Java man, just a few channel crossings over in Indonesia).  Tropical conditions in much of the region and the minimal research funds available for archaeology in Asia until very recently could also explain this gap in the fossil record. 

The absence of archaic non-Neanderthal admixture in existing mainland Asian populations, also points to limited or non-existence admixture between ordinary Homo erectus and modern humans although the population genetic evidence poses very different preservation concerns.  In the case of population genetics the strongest possibility to account for is the possibility that subsequent waves of modern humans may have entirely replaced the earlier waves of modern humans in Asia that could have admixed with Homo erectus. 

There is also no substantial evidence that there was ever a Neanderthal presence anywhere significantly to the east of India, which is notable given how well the lithic tool culture of Neanderthals has been studied and how well lithic tools can be preserved even when skeletal remains are not preserved.  It could be that bamboo or some other perishable tool materials were more attractive in Southeast Asia than stone and that this disrupted the culturally transmission of Neanderthal lithic industries, but this seems fairly implausible to me given that earlier archaic lithic traditions found in Africa were transmitted to Southeast Asia around 2 million years ago when Homo erectus arrived in Asia.

Thus, a lack of other good alternative candidates is another reason to suspect that Denisovan admixture in the modern human genome is really Homo floresiensis admixture.

Bottom Line: Hobbits May Be Among The Ancestors Of People Alive Today

The bottom line is that a variety of factors make Homo floresiensis a particularly attractive potential source for so called "Denisovan" admixture observed in modern humans. Indeed, I would argue that they are the most likely source of this archaic admixture in modern humans.

In the most likely hypothesis, Homo floresiensis were a pygmy derivative of Homo erectus, and the Denisovan samples of ancient DNA from Siberia look like a source of admixture because they are also derived, at least in substantial part, from a common Homo erectus ancestor.

Were Hobbits The Last Archaic Hominins On Earth?

Probably as a result of their geographic isolation and possibly also as a result of a stable symbiotic relationship with co-existing modern humans on Flores, Hobbits may have been one of the last archaic hominin species to go extinct. 

A conservative estimate suggests that they went extinct 17,000 years ago.   This is around the time of the last glacial maximum and would suggest that an influx of a new wave of modern humans at this time could have caused their extinction.

But, there is good evidence that they persisted as recently as 12,000 to 13,000 years ago.   See Morwood, M. J.; Soejono, R. P., et al.,"Archaeology and age of a new hominin from Flores in eastern Indonesia". Nature 431 (7012): 1087–1091 (October 27, 2004) and Morwood, M. J.; Brown, P., et al.,"Further evidence for small-bodied hominins from the Late Pleistocene of Flores, Indonesia". Nature 437 (7061): 1012–1017 (October 13, 2005). As Wikipedia explains:
Local geology suggests that a volcanic eruption on Flores approximately 12,000 years ago was responsible for the demise of H. floresiensis, along with other local fauna, including the elephant Stegodon.   
The estimated date of their extinction 12,000 years ago is about 12,000 years after the most recent known Neanderthal remains and about 80,000 years after the most recent reliably dated and typed Homo erectus remains. It is fairly close in time to a couple of inferred dates of admixture between archaic hominins and Paleo-African populations (i.e. modern human pygmies and Khoisan populations in South Africa) based on population genetic analysis for which there are no fossil remains, in part, due to poor preservation conditions in tropical Africa.

Did Homo floresiensis survive into the modern era? 

There is also a legitimate case to be made for a much more recent demise of H. floresiensis,
Gregory Forth hypothesized that H. floresiensis may have survived longer in other parts of Flores to become the source of the Ebu Gogo stories told among the Nage people of Flores. The Ebu Gogo are said to have been small, hairy, language-poor cave dwellers on the scale of this species. Believed to be present at the time of the arrival of the first Portuguese ships during the 16th century, these creatures are claimed to have existed as recently as the late 19th century.  Gerd van den Bergh, a paleontologist working with the fossils, reported hearing of the Ebu Gogo a decade before the fossil discovery.
This remains a part of the living oral history of these people.

At least one reputable linguist has conjectured, but cannot prove, that the linguistic structure of one of the main languages spoken in Flores reflects the effects of contact with Homo floresiensis, who may have served as servants of early modern humans in Flores. This makes some sense. It is hard to see how to hominin species could manage to co-exist in a geographic niche as small as the island of Flores for 32,000 without either causing the other to go extinct, if these communities did not live in a symbiotic, cooperative relationship with each other.

A linguistic connection, if there is one, suggests strongly that some population of Homo floresiensis survived long after the volcanic erruption 12,000 years ago and lends credence to the legends that claim that they actually went extinct somewhere in the last five hundred years, as a time depth of 12,000 years would be too far in the past to leave the kind of linguistic trace suggested.

Does the species survive today?
On the island of Sumatra, there are reports of a 1–1.5 m (3 ft 3 in–4 ft 10 in) tall humanoid, the Orang Pendek which might be related to H. floresiensis. Henry Gee, senior editor at Nature magazine, speculates that species like H. floresiensis might still exist in the unexplored tropical forest of Indonesia.
The evidence cited to the effect that some Orang Pendek may be a non-extinct species on Sumatra, while not bringing their existence to the level of an incontrovertable scientifically discovered fact, is not insubstantial.
[The Orang Pendek] has allegedly been seen and documented for at least one hundred years by forest tribes, local villagers, Dutch colonists, and Western scientists and travelers. Consensus among witnesses is that the animal is a ground-dwelling, bipedal primate that is covered in short fur and stands between 80 and 150 cm (30 and 60 in) tall. . . . Hundreds of locals claim to have either seen the animal personally or can relate stories of others who have.
These observations are tied to a particular location:
While Orang Pendek or similar animals have historically been reported throughout Sumatra and Southeast Asia, recent sightings have occurred largely within the Kerinci regency of central Sumatra and especially within the borders of Taman Nasional Kerinci Seblat (Kerinci Seblat National Park) (TNKS).[1][2][8] The park, 2° south of the equator, is located within the Bukit Barisan mountain range and features some of the most remote primary rainforest in the world. Habitat types within the park include lowland dipterocarp rainforest, montane forests, and volcanic alpine formations on Mt. Kerinci, the second highest peak in Indonesia.[8] Because of its inaccessibility, the park has been largely spared from the rampant logging occurring throughout Sumatra and provides one of the last homes for the endangered Sumatran Tiger.
If the Orang Pendek really does still exist, or did until recently, and DNA samples and skeletal remains could be obtained, this would be a truly extraordinary discovery.  Certainly, the search deserves more resources than the one year National Geographic study funded effort in 2009 by a lonely couple of investigators.

This article was updated with links and some additional material on January 15, 2013.  The sentence in the section "Did Homo floresiensis survive into the modern era?" following the blockquote was added on May 29, 2015.