Friday, May 31, 2019

Northern Route Migration

Assuming that humans dispersed into Asia predominantly via a southern coastal route is firmly rooted in conventional wisdom. But, the evidence is far more equivocal on the question. 
Northern and Central Asia have been neglected in studies of early human migration, with deserts and mountains being considered uncompromising barriers. However, a new study argues that humans may have moved through these extreme settings in the past under wetter conditions. By analyzing past climate, northern Asia emerges as a potential route of human dispersal, as well as a zone of potential interaction with other hominins such as Neanderthals and Denisovans.
From here.

Feng Li, Nils Vanwezer, Nicole Boivin, Xing Gao, Florian Ott, Michael Petraglia, Patrick Roberts. "Heading north: Late Pleistocene environments and human dispersals in central and eastern Asia." PLOS ONE, 2019; 14 (5): e0216433 DOI: 10.1371/journal.pone.0216433

Probabilistic Vocalizations

Titi monkeys have a communications system with each other that is not categorical. Even the concept as explained in this linked blog post from John Hawks is hard to get your head around. From the paper discussed in the blog post:
Although the notion of categorical meaning is intuitively compelling, it is not necessarily the default mode of animal perception. Categorical perception has been a major theoretical pillar in animal communication research, particularly because of its intuitive link to linguistic theory. For example, Macedonia and Evans [(16), p. 179] presupposed that external events are processed in categorical terms (“…all eliciting stimuli must belong to a common category”). Although this approach has been fruitful and productive, it has also generated enigmas suggesting that the underlying theory may have to be revised. For example, in a seminal paper, Cheney and Seyfarth (17) were puzzled by the fact that animals appeared to have very few categorical semantic labels, mostly limited to predator classes and a few social events. One possibility is that graded meanings are the default way of animal communication [e.g., (18)], although this hypothesis has been much ignored and considered as less interesting than categorical perception (16). Our study suggests that explaining animal communication on categorical terms alone may be too restrictive and anthropocentric and may explain the struggle to extract meaning from some animal communication systems.

Thursday, May 30, 2019

Teaching Science v. Celebrating Science

Warning: There are no spoilers in this post, but there are in the linked source material.

Many commentators on science fiction assume that science fiction should accurately explain science because it is teaching people about science. But, usually, it isn't doing that, so accuracy isn't the point. This doesn't mean that there is no relationship between science and science fiction. But, it is as much about eternal narratives and cultural alternatives, as it is about hard science, in many cases.
The a movie like Avengers: Endgame doesn’t teach science, or even advertise it. It does celebrate it though. 

That’s why, despite the silly half-correct science, I enjoyed Avengers: Endgame. It’s also why I don’t think it’s inappropriate, as some people do, to classify movies like Star Wars as science fiction. Star Wars and Avengers aren’t really about exploring the consequences of science or technology, they aren’t science fiction in that sense. But they do build off science’s role in the wider culture. They take our world and look at the advances on the horizon, robots and space travel and quantum speculations, and they let their optimism inform their storytelling.
From 4gravitons

The Particle Data Group's 2019 Update Is Now Live

The Particle Data Group combines all of the experimental data on fundamental particles and hadrons to establish global averages. 

One of the most notable of the new data points in 2019 is the Higgs boson mass which is now 125.10 ± 0.14 GeV.  Previously in 2018 it was 125.18 ± 0.16 GeV. The significance of the difference between the PDG 2019 value for the Higgs boson mass and the 124.65 GeV value that would make the Higgs boson mass squared plus the W boson mass squared plus the Z boson mass squared equal to exactly one half of the Higgs vev squared is 3.21 sigma, only slightly changed from the 3.31 sigma of the 2018 value as the uncertainty is reduced by 22% relative to  last year, in short, still strongly disfavored but not completely ruled out either.

The W and Z boson masses are unchanged. The most recent LHC data for the W boson mass (from 2018 using Run-1 data) tugs down a little to 80.370 ± 0.018 GeV relative to the current fit of 80.379 ± 0.012 GeV, but not enough to pull down the global average. A global fit of the W boson mass with the Higgs boson mass and top quark mass suggests a value of 80.362 +/- 0.002 GeV. The most recent Z boson mass data is from 2001.

2018 Quark Masses v. 2019 Quark Masses v. FLAG19 (in MeV)

top quark 173,000 ± 400 v. 172,900 ± 400
bottom quark 4,180 +40-/-30  v. 4,180 + 30/-20 v. 4,198 ± 12
charm quark 1,275 +25/-35 v. 1,270 ± 20  v. 1,282 ± 17
strange quark 95+9/-3 v. 93 +11/-5 v.  93.12 ± 0.69
down quark 4.7 + 0.5/-0.4 v. 4.67 +0.48/-0.17 v. 4.88 ± 0.2
up quark 2.2 +0.5/-0.4 v. 2.16 + 0.49/-0.26 v. 2.5 ± 0.17

All of the PDG 2019 values are consistent with the FLAG19 values.

Curiously, the PDG strange quark mass uncertainty has increased even as the uncertainty in the other four non-top quark masses has declined and the uncertainty in the top quark mass has remained the same. It is also puzzling that FLAG19 reports an uncertainty in its determination of the strange quark mass (despite having a central value that has dropped to be consistent with the FLAG19 value) that is more than eleven times smaller than PDG 2019 does, even though the other error margins for FLAG19 values are smaller than the PDG values but of the same order of magnitude.

The small downward shift in the global average of direct top quark mass measurements pulls it away from the value it would need to have for the sum of the square of the fundamental fermion masses in the Standard Model to equal half of the Higgs vev squared, which is about 174,040 MeV which is 2.85 sigma from the directly measured value.  But, this is balanced out a bit by indirect measurements of the top quark pole mass of about 173,100 ± 900 MeV. The error weighed average of the direct and indirect top quark mass measurements in PDG 2019 is 172,960 ± 366 MeV, which is 2.95 sigma from 174,040 MeV. As in the case of the Higgs boson mass, this is still strongly disfavored but not completely ruled out either. But, the likelihood that both the top quark mass measurements is too low by 2.95 sigma and the Higgs boson mass measurement is high by 3.2 sigma is very low indeed.

But, since the deviations from these values are in opposite directions and similar in magnitude, the possibility the less stringent relationship, that the sum of the square of the fundamental particle masses is equal to the square of the Higgs vev, is still perfectly consistent with the data. So, the LC & P relationship lives another year.

While FLAG19 values are based purely on state of the art lattice QCD determinations, the PDG 2019 values aren't based on methodologies that are much different.

The charged lepton masses are unchanged. I didn't determine if the neutrino mass eigenstate differences, and mixing angles were precisely the same in 2019 as they were in 2018, but the neutrino mass eigenstate differences are at a minimum, very similar to at least two significant digits.

When Herders And Foragers First Met In Africa, They Did What Comes Naturally To Humans

New ancient DNA from Africa sheds light on how the first herders in Africa found mates among Africa's foragers. 
DNA analysis shows that African herders and foragers mated with each other in two phases, says a team led by archaeologist Mary Prendergast of Saint Louis University in Madrid. After entering northeastern Africa from the Middle East around 8,000 years ago, herders swapped DNA with native foragers between roughly 6,000 and 5,000 years ago. Herders possessing some forager heritage then trekked about halfway down the continent and mated with eastern African foragers around 4,000 years ago, the scientists report online May 30 in Science. . . .
Early African herders inherited about 20 percent of their DNA from foragers, mostly via mating that occurred before 5,000 years ago, the scientists say. Herders then spread rapidly throughout eastern Africa after 3,300 years ago, mating little with foragers along the way. 
From here. The source paper is:

M.E. Prendergast et al. Ancient DNA reveals a multistep spread of the first herders into sub-Saharan Africa. Science. Published online May 30, 2019. doi:10.1126/science.aaw6275.

The abstract is as follows:
How food production first entered eastern Africa ~5000 years ago and the extent to which people moved with livestock is unclear. We present genome-wide data from 41 individuals associated with Later Stone Age, Pastoral Neolithic (PN), and Iron Age contexts in what are now Kenya and Tanzania to examine the genetic impacts of the spreads of herding and farming. Our results support a multi-phase model in which admixture between northeastern African-related peoples and eastern African foragers formed multiple pastoralist groups, including a genetically homogeneous PN cluster. Additional admixture with northeastern and western African-related groups occurred by the Iron Age. These findings support several movements of food producers, while rejecting models of minimal admixture with foragers and of genetic differentiation between makers of distinct PN artifacts.

Mathematics As A Mature Discipline

How mature is mathematics as a discipline?

Probably less than 2% of adults will ever master any kind of math more modern than the advances made by Leohard Euler, who died in 1783, and fewer people still can understand all the contributions he made to mathematics and other scientific disciplines. His intellectual legacy began to accumulate around 1726.

Calculus, now studied by many students late in high school or in their freshman year in college, was invented by Newton and Leibniz in the late 1600s.

Alexander the Great, who died around 323 BCE, studied some of the same mathematical subjects that are found in high school classes called trigonometry or pre-calculus (e.g. conic sections).

Most Americans spend a year in school studying geometry concepts that were in place and improved upon by Pythagoras who died around 495 BCE.

Tuesday, May 28, 2019

They Are Building A Neutrino Telescope At The Bottom Of The Mediterranean Sea

This neutrino telescope isn't just at the bottom of the sea. It's looking down, not up.
Deep under the Mediterranean Sea, hundreds of watchful eyes hang suspended on cables, waiting for a rare and valuable flash. Their quarry are ghostly neutrino particles, capable of tunneling through light-years of space and a planet’s worth of rock without ever coming into contact with matter. 
But, here, under the ocean, they just might hit a detector from the Cubic Kilometre Neutrino Telescope, or KM3NeT. While the international collaboration is still in the early stages of construction, it hopes to soon begin tracking some of the most elusive particles in the universe. 
Neutrinos are nearly massless particles produced in the sun and in energetic events like supernovas, colliding stars, and gamma-ray bursts. Because the particles barely interact with the rest of the universe, they are notoriously difficult to study, though trillions pass through your body every second. 
Researchers have tended to bury neutrino detectors in vats of supercooled liquids or miles underground, hoping that neutrinos will be the only particles that make it through.
This time, researchers are hiding the detectors at the bottom of the sea, on the other side of the planet from the skies they hope to study, to block everything but neutrinos from hitting their detectors.
From here (emphasis added).

For what it is worth, at this moment in time, I think that innovative big telescopes (like this one and the new gravitational wave telescopes) are a better investment to answer the solvable questions about the fundamental laws of physics that we haven't solved yet than a new particle accelerator that is seven to twelve times as big as the biggest one we've built yet.

Someday, the time may be ripe to build a new accelerator. But, we can almost guarantee that we won't find anything really revolutionary by increasing the energy scale of the collisions by one order of magnitude. We'd have been getting hints via indirect indications, albeit inconclusive, of what is going on at higher energies already if that was going to happen. But, we haven't been seeing that.

In contrast, we know for a fact that it takes some sort of new physics to explain dark matter and dark energy phenomena, and we have very good reason to think that new data can tell us more about neutrinos and the history of the universe (i.e. cosmology). And, we are getting so much new data, simultaneously, from so many independent sources of new observations, that we actually are making progress on those questions, even though it may not alway seem like that on a day to day basis.

Wednesday, May 22, 2019

What do scientists mean when they say that something exists?

Sabine Hossenfelder does her usual spot on job of navigating through the weeds of what it means in science to say that something exists, using the Higgs boson, quarks, and gravitational waves as examples. An excerpt:
When we say that these experiments measured “gravitational waves emitted in a black hole merger”, we really mean that specific equations led to correct predictions.

It is a similar story for the Higgs-boson and for quarks. The Higgs-boson and quarks are names that we have given to mathematical structures. In this case the structures are part of what is called the standard model of particle physics. We use this mathematics to make predictions. The predictions agree with measurements. That is what we mean when we say “quarks exist”: We mean that the predictions obtained with the hypothesis agrees with observations. 
She goes on to discuss the philosophical concept of "realism" and to, appropriately, dismiss it as basically irrelevant. 

Saturday, May 18, 2019

Modern Humans Were Cooking Starchy Plants 120,000 Years Ago

Flour has been in use since the Upper Paleolithic era in Europe (ca. 40,000 years ago) and in pre-Columbian, pre-Neolithic North American, but this example is much older.
"Our results showed that these small ashy hearths were used for cooking food and starchy roots and tubers were clearly part of their diet, from the earliest levels at around 120,000 years ago through to 65,000 years ago," says Larbey. "Despite changes in hunting strategies and stone tool technologies, they were still cooking roots and tubers." 
. . .

By combining cooked roots and tubers as a staple with protein and fats from shellfish, fish, small and large fauna, these communities were able to optimally adapt to their environment, indicating great ecological intelligence as early as 120,000 years ago. 
"Starch diet isn't something that happens when we started farming, but rather, is as old as humans themselves," says Larbey. Farming in Africa only started in the last 10,000 years of human existence.
From here.

The paper is:

Cynthia Larbey, et al., "Cooked starchy food in hearths ca. 120 kya and 65 kya (MIS 5e and MIS 4) from Klasies River Cave, South Africa." 131 Journal of Human Evolution 210 (2019). DOI: 10.1016/j.jhevol.2019.03.015

Proposed Solution To Voynich Code Published

Language Log has a nice analysis of the most recent published claim to have solved the great linguistic mystery of the Voynich Code.
"The Language and Writing System of MS408 (Voynich) Explained" In Romance Studies. Published online: 29 Apr 2019 
[VHM: MS 408 is the call number under which the Voynich manuscript is catalogued in Yale University's Beinecke Rare Book and Manuscript Library, to which it was donated by Hans P. Kraus in 1969.] 
Manuscript MS408 (Voynich) is unusual in a number of respects: 1. It uses an extinct language. 2. Its alphabet uses a number of unfamiliar symbols alongside more familiar symbols. 3. It includes no dedicated punctuation marks. 4. Some of the letters have symbol variants to indicate punctuation. 5. Some of the symbol variants indicate phonetic accents. 6. All of the letters are in lower case. 7. There are no double consonants. 8. It includes diphthong, triphthongs, quadriphthongs and even quintiphthongs for the abbreviation of phonetic components. 9. It includes some words and abbreviations in Latin. As a result, identifying the language and solving the writing system required some ingenuity and lateral thinking, but both were duly revealed. The writing system is rather more singular and less intuitive than modern systems, which may explain why it failed to become culturally ubiquitous and ultimately became obsolete. On the other hand, a significant vestige of the language has survived into the modern era, because its lexicon has been sequestered into the many modern languages of Mediterranean Europe. Here, the language and writing system are explained, so that other scholars can explore the manuscript for its linguistic and informative content.
Established experts strongly disagree that this proposed solution is accurate:
"Cheshire reCAsT", J. K. Petersen, The Voynich Portal (5/7/19) 
"Cheshire Reprised", J. K. Petersen, The Voynich Portal (5/16/19) 
"No, someone hasn’t cracked the code of the mysterious Voynich manuscript. Medieval scholar: "Sorry, folks, 'proto-Romance language' is not a thing."" Jennifer Ouellette, Ars Technica (5/15/19)

Etruscans in Poland?

"The Pomeranian culture, was an Iron Age culture with origins in parts of the area south of the Baltic Sea, from the 7th c. to the 3rd c. BC, which eventually covered most of today's Poland" that has a lot of material culture in common with the Etruscans of Northern Italy (one of the last attested linguistically non-Indo-European people in Europe) and other Mediterranean people of uncertain linguistic affiliation, according to a fairly convincing post at the Old European Culture blog. The most plausible route of the connection is via the Iron Age "Amber Road". But, the artifacts shared by these cultures don't appear in places in between them.

Tuesday, May 14, 2019

New Definitions Of Metric Units Take Effect On May 20, 2019

New definition of the international system of units will take effect on May 20, 2019.
The international system of units, the SI, is the system of units in which:
* the unperturbed ground state hyperfine splitting frequency of the caesium 133 atom  is exactly   hertz,
* the speed of light in vacuum  is exactly    meter per second,
* the Planck constant  is exactly    joule second,
* the elementary charge  is exactly  coulomb,
* the Boltzmann constant  is exactly    joule per kelvin,
* the Avogadro constant  is exactly    reciprocal mole,
* the luminous efficacy  of monochromatic radiation of frequency hertz is exactly  lumen per watt,
where the hertz, joule, coulomb, lumen, and watt, with unit symbols , and , respectively, are related to the units second, meter, kilogram, ampere, kelvin, mole, and candela, with unit symbols , K,, and , respectively, according to the relations (for periodic phenomena), , and . The steradian, symbol , is the SI unit of solid angle and is a special name and symbol for the number s  so that
Deriving Basic Units

The means by which these constants should be operationalized is also spelled out in the fine print. Specifically:
The choice of physical constants was made on the basis of minimal uncertainty associated with measuring the constant and the degree of independence of the constant in respect of other constants that were being used. Although the BIPM has developed a standard mise en pratique (practical technique) for each type of measurement, the mise en pratique used to make the measurement is not part of the measurement's definition – it is merely an assurance that the measurement can be done without exceeding the specified maximum uncertainty.
Caesium 133 is used to define the second. The Planck constant is used to define the joule given the second. Boltzmann constant is used to define the degree Kelvin given the joule. The speed of light is used to define the meter given the second. The kilogram, meter and second are used to define the watt. The second and the watt and the properties of a laser of a certain color are used to define the lumen and candela. The elementary charge is used to define the coulomb which is used with the second to define the ampere. The steradian is mathematically defined.

Casesium 133, Planck's constant and the speed of light could also be used to determine the kilogram and the kilogram's mass can also be determined directly from the definition of the mole (I would think that the former is as a practical matter easier to get precise about than the latter). So, the mole is just an alternative (potentially not quite exactly the same at the part per billion level) way to define the kilogram and could have been omitted, even though as a practical matter it is probably easier to operationalize that the method using casesium 133, Planck's constant and the speed of light. A presume that the fine print favors one method over the other, or at least resolves the conflict, if there is a discrepancy between two ways of defining the kilogram.

The History Of The Metric System

In some ways, the reform represents a return to the metric system's historic roots in physical constants after the Enlightenment motivated post-French Revolution thought that spawned it.

The original definition of the meter adopted in March of 1791 was one ten millionth of the distance between the North Pole and the Equator through Paris. From 1889 until 1960, the meter was defined in terms of reference objects. 

From 1889 until May 20, 2019, the kilogram has been defined in terms of reference objects. But, the gram was calibrated originally to be equal to the mass of one cubic centimeter of water. 

The size of the degree in Celsius and Kelvin temperatures is designed to be 1% of the difference in temperature between the freezing point of water and the boiling point of water. 

The calorie was originally the amount of heat required to raise the temperature of 1 kg of water from 0 to 1 °C at 1 atmosphere of pressure.

The original definition of the second was based on Earth's average rotation during 1750–1892, which takes, on average, about 31,556,736 seconds (60 seconds a minute, 60 minutes an hour, 24 hours a day, 365 days a year except in leap years divisible by four and not divisible by 100 when there are 366 days a year).

An erg is the amount of work done by a force of one dyne exerted for a distance of one centimeter. In the CGS base units, it is equal to one gram centimeter-squared per second-squared (g⋅cm2/s2). It is thus equal to 10^−7 joules or 100 nanojoules (nJ) in SI units.

The joule is an energy unit that flows naturally from thinking in terms of kilograms, meters and seconds (it is one kg*meter squared per second squared a.k.a. one Newton meter a.k.a. one Pascal times cubic meters). It can also be defined as:

* The work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb-volt (C⋅V). This relationship can be used to define the volt.

* The work required to produce one watt of power for one second, or one watt-second (W⋅s) (compare kilowatt-hour – 3.6 megajoules). This relationship can be used to define the watt.

Current in ampere's was defined by setting the magnetic force constant  to unity and electric potential is defined in such a way as to ensure the unit of power calculated by the relation is an erg/second. This was slightly refined to produce the current soon to be replaced definition of the ampere which was that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 m apart in vacuum, would produce between these conductors a force equal to 2×10^−7 newton per meter of length (i.e. two dynes).

The previous definition of the mole was the amount of substance of a system that contains as many elementary entities as there are atoms in 0.012 kilogram of carbon-12 (i.e. in 1 gram of a carbon-12 standard based atomic mass unit). The mole was thus derive of the gram which was derivative of the mass of one cubic centimeter of water which was derivative of the meter.

The new physical constant based definitions still bear homage to these motivating concepts for metric system basic units, as the numbers selected aren't natural at all in their own reference frames.

Other Impacts

All measurements in the U.S. customary system of measurements are defined exactly in terms of S.I. units, so they will also change subtly on May 20, 2019.

The inch in the U.S. customary system is defined to be exactly 0.0254 meters, so all U.S. customary measurements of length, area and volume will change on May 20, 2019. The U.S., the United Kingdom and other Commonwealth countries agreed on this definition effective July 1, 1959. (The speed of light in miles per second will now be: 186,282.397 to the nearest part per billion, leaving a rounding error of about 1 part per 20 billion.)

Likewise, the U.S. customary system pound is defined to be exactly 435.59237 grams by agreement between the U.S., the United Kingdom, and other English-speaking countries in 1959, so all units of weight in the U.S. customary system (or strictly speaking analogs of U.S. customary system measurements of weight converted to measurements of mass).

The degree Fahrenheit, which is defined as exactly 5/9ths of a degree Kelvin in magnitude, so it will change on May 20, 2019. 

A degree Celsius and a degree Kelvin are defined to be equal in magnitude. There is an exact conversion between degrees Celsius and degrees Fahrenheit (since 32 degrees Fahrenheit is exactly 0 degrees Celsius and 212 degrees Fahrenheit is exactly 100 degrees Celsius). But, Celsius is not an S.I. unit. 

By international agreement, since 1954 the unit degree Celsius and the Celsius scale are defined by absolute zero and the triple point of Vienna Standard Mean Ocean Water (VSMOW), a specially purified water. This definition also precisely relates the Celsius scale to the Kelvin scale, which defines the SI base unit of thermodynamic temperature with symbol K. Absolute zero, the lowest temperature possible, is defined as being exactly 0 K and −273.15 °C. The temperature of the triple point of water is defined as exactly 273.16 K (0.01 °C).

The calorie is also a metric, but non-S.I. unit based upon the properties of water. It is the amount of energy needed to heat on cubic centimeter of liquid water (which has a mass of one gram) by one degree Celsius. It is about 4.1868 J. A dieter's calorie is 1000 calories or one kilocalorie, or about 4186.8 J.

How to change from U.S. customary units to metric units.

I have long recommended that the U.S. make the change over to metric units partially, first converting (1) from Fahrenheit to Celsius and Rankine to Kelvin, (2) from horse power to watts, (3) from BTUs and tons of refrigeration and foot-pounds to joules and calories, and (4) from slugs to Newtons, while deferring conversion of more familiar units later. Since few people use Rankine, tons of refrigeration, foot-pounds and slugs, those conversions would be painless. More people use horse power and BTUs, but both are used on a very isolated basis and would require reforms primarily by a few big corporations in a small number of industries. For most people, the first wave would primarily mean converting from Fahrenheit to Celsius.

Conversion from more familiar U.S. customary units of length, area, volume and weight to metric and S.I. units would take place later, to minimize the amount of conversion shock taking place at one time. This is because so many legacy measurements (e.g. land surveys and recipes) are in convenient multiples of U.S. customary units.

This would probably best be broken up into different waves based upon the industry or type of thing measured, continuing current trends which use metric units for some purposes and U.S. customary units for others.


One of the subtle issues of the redefinitions is that it obscures, without truly eliminating, issues related to the precision with which we can measure the physical constants that are given exact defined values (most of which were in the parts per billion plus or minus an order of magnitude). The new definitions are generally designed to match existing values to nine significant digits of precision.

I'm disappointed that they didn't decide to define the speed of light in a vacuum to be exactly 300 000 000 meters per second, even though I understand why they did (for back compatibility). The difference would be a reduction of 0.7 millimeters per meter.

Likewise, if we were starting over from scratch, defining the coulomb as as 1 x 10^19 elementary electric charges would have made sense. But, we are victims of our past.