Tuesday, January 22, 2019

Ciao

The following analysis of the Italian word "ciao" is from here:
I often close letters with "ciao", which means both "hello; hi" and "bye; goodbye". When I do this, I am essentially saying "I am your slave". 
Borrowed from Italian ciao (“hello, goodbye”), from Venetian ciao (“hello, goodbye, your (humble) servant”), from Venetian s-ciao / s-ciavo (“servant, slave”), from Medieval Latin sclavus (“Slav, slave”), related also to Italianschiavo, English Slav, slave and Old Venetian S-ciavón ("Slav"), from LatinSclavonia (“Slavonia”). Not related to Vietnamese chào (“hello, goodbye”).
Wiktionary 
The Italian salutation ciao, which is now popular in many parts of the world outside Italy, originated in the dialects of northern Italy. In the dialect of Venice, ciau literally means "servant, slave," and is also used as a casual greeting, "I am your servant." Dialectal ciau corresponds to standard Italian schiavo, "slave," and both words come from Medieval Latin sclāvus. Declaring yourself someone's slave might seem like an extravagant gesture today, but expressions such as Your obedient servant or Your servant, madam were once commonplace in English. Similarly, the Classical Latin word servus meaning "slave" is still used as an informal greeting in southern Germany and in Austria, the Czech Republic, Slovakia, Hungary, Poland, Romania, Ukraine, and other parts of central Europe that were formerly part of the Austro-Hungarian Empire. At the opposite end of the world, in Southeast and East Asia, one even finds words that originally meant "slave"or "your slave" but have developed into pronouns of the first person through their use in showing respect and humility. In Japanese, for example, the word boku is used to mean "I, me," especially by boys and young men, and it comes from a Middle Chinese word meaning "slave" or "servant" and now pronounced pú in Mandarin.
American Heritage Dictionary, 5th ed.

Monday, January 21, 2019

Passings Of Little Known Great Minds

Woit has had three obituaries at his Not Even Wrong blog since Christmas Eve. All three are brilliant people, although none are household names.



Another Dark Matter-Less Galaxy (NGC1052-DF4) Is It Proof Of MOND?

This paper replicates the result seen in a sister galaxy. MOND explains this with the "External Field Effect" something absent from conventional General Relativity.

A second galaxy missing dark matter in the NGC1052 group

The ultra-diffuse galaxy NGC1052-DF2 has a very low velocity dispersion, indicating that it has little or no dark matter. Here we report the discovery of a second galaxy in this class, residing in the same group. NGC1052-DF4 closely resembles NGC1052-DF2 in terms of its size, surface brightness, and morphology; has a similar distance of D=19.9±2.8 Mpc; and has a similar population of luminous globular clusters extending out to 7 kpc from the center of the galaxy. Accurate radial velocities of seven clusters were obtained with the Low Resolution Imaging Spectrograph on the Keck I telescope. Their median velocity is v=1445 km/s, close to the central velocity of 22 galaxies in the NGC1052 group. The rms spread of the observed velocities is very small at σobs=5.8 km/s. Taking observational uncertainties into account we determine an intrinsic velocity dispersion of σintr=4.2+4.42.2 km/s, consistent with the expected value from the stars alone (σstars7 km/s) and lower than expected from a standard NFW halo (σhalo30 km/s). We conclude that NGC1052-DF2 is not an isolated case but that a class of such objects exists. The origin of these large, faint galaxies with an excess of luminous globular clusters and an apparent lack of dark matter is, at present, not understood.
A tweet from van Dokkum states:
and I found a twin of NGC1052-DF2, with the same weird population of globular clusters and super low velocity dispersion. Meet NGC1052-DF4! What the paper can't convey is how incredibly surprised we were!
He also tweeted this image of the system (which naively makes it look further from NGC 1052 but closer to NGC 1035), but it is hard to discern distances between objects since depth is not known with that precision.



A previous posts on point can be found here and here. The authors explain in the introduction the implication of these results for the dark matter paradigm:
With this confirmation, the central unanswered question is whether NGC1052-DF2 is an isolated case or representative of a population of similar galaxies. This is important for judging the likelihood of interpretations that require unusual orbits or viewing angles (see, e.g., Ogiya 2018) and, most importantly, for judging the relevance of NGC1052-DF2 for our ideas about galaxy formation and the relation between dark matter and normal matter. With the important exception of tidal dwarfs (Bournaud et al. 2007; Gentile et al. 2007; Lelli et al. 2015), it is thought that a gravitationally-dominant dark matter halo is the sine qua non for the formation of a galaxy. If galaxies such as NGC1052-DF2 are fairly common we may have to revise our concept of what a galaxy is, and come up with alternative pathways for creating galaxy-mass stellar systems. Here we report the discovery of a galaxy that shares essentially all of NGC1052-DF2’s unusual properties, to a remarkable degree. It is in the same group, has a similar size, luminosity, and color, the same morphology, the same population of luminous globular clusters, and the same extremely low velocity dispersion.
In contrast, MOND understands why this is happening and predicted this result before "The Breakfast Club" was in theaters in the early 1980s.

Galactic Rotation Curves Still Well Behaved

There have actually been a lot of interesting papers about gravity and dark matter in the past little while, but given ill health I'll also simply note this one without much comment or formatting. It affirms and refines the data supporting some kind of modified gravity hypothesis.

The baryonic Tully-Fisher relation for different velocity definitions and implications for galaxy angular momentum

Federico Lelli (1), Stacy S. McGaugh (2), James M. Schombert (3), Harry Desmond (4), Harley Katz (4) ((1) European Southern Observatory, (2) Case Western Reserve University, (3) University of Oregon, (4) University of Oxford)
We study the baryonic Tully-Fisher relation (BTFR) at z=0 using 153 galaxies from the SPARC sample. We consider different definitions of the characteristic velocity from HI and H-alpha rotation curves, as well as HI line-widths from single-dish observations. We reach the following results: (1) The tightest BTFR is given by the mean velocity along the flat part of the rotation curve. The orthogonal intrinsic scatter is extremely small (6%) and the best-fit slope is 3.85+/-0.09, but systematic uncertainties may drive the slope from 3.5 to 4.0. Other velocity definitions lead to BTFRs with systematically higher scatters and shallower slopes. (2) We provide statistical relations to infer the flat rotation velocity from HI line-widths or less extended rotation curves (like H-alpha and CO data). These can be useful to study the BTFR from large HI surveys or the BTFR at high redshifts. (3) The BTFR is more fundamental than the relation between angular momentum and galaxy mass (the Fall relation). The Fall relation has about 7 times more scatter than the BTFR, which is merely driven by the scatter in the mass-size relation of galaxies. The BTFR is already the "fundamental plane" of galaxy discs: no value is added with a radial variable as a third parameter.
It turns out that there are actually quite a few ways that you can tweak gravity to produce this result. This kind of detail helps to discriminate between them. The chart below is a screenshot from the paper capturing its central conclusion:

Friday, January 18, 2019

Quote of The Day

Scientists found that while Pluto was originally a planet, it no longer identifies as one. So we need to respect its position as a Trans-Neptunian Object… along with all the other trans-planets.
From here (Chris Rusche, July 21, 2014).

Still need a little more humor to meet the 3% quota.

Atomic Structure

This blog had a humor deficit that I'm working to backfill.


From here.

Fun fact: 43 out of 1571 posts at this blog are tagged humor (about 3%).

Monday, January 14, 2019

More Evidence That Hobbits Aren't Dwarf Erectus

A 2018 paper from Sweden adds more evidence to the conclusion of two prior papers which conclude that:
H. floresiensis seems to be deeply rooted in the phylogeny of Homo and not closely related to Indonesian H. erectus.
From John Hawks.

Problems With The Hypothesis The Bell Beaker People Derive From The Hungarian Yamnaya

Davidski at Eurogenes points out some problems in the ancient DNA evidence with the hypothesis that the Northern and Central European Bell Beaker people are derived from the Hungarian Yamnaya people. There are lots of archeological and geographic reasons why this hypothesis is plausible and the autosomal genetic evidence isn't inconsistent with this hypothesis, but the ancient Y-DNA data doesn't really support this conclusion so far.

We care because the Bell Beaker people were the last major wave of migration into Northern and Western Europe (in the late Copper Age and Bronze Age) before the gene pools in those regions came to be very similar to those of modern Europe. The Bell Beaker people are also notable because many people believe (although I am somewhat skeptical of the claim for reasons beyond the scope of this short post) that the Bell Beaker people were the original Indo-Europeans in this part of Europe. At any rate, the Bell Beaker people without a doubt were very important in causing the people of Western Europe and Northern Europe to become the people that they are today.

We know, in very general terms that the Bell Beaker people have significant European steppe ancestry, and we know about when they started to appear on the scene, but we lack the kind of more specific understanding of where in particular they came from and what route they took that we have in the case of many other notable mass migration in world history (especially in the late prehistoric period).

Good Problems And Non-Problems

I agree 100% with Sabine Hossenfelder's list of what are and are not "good problems" in fundamental physics in a recent post at Backreaction.

In short: inconsistencies between accepted theories or between accepted theories and observation are problems, while dissatisfaction with the form of the laws of Nature that have been experimentally discerned are not.

I would add that it isn't inherently wrong to look for more elegant ways to describe existing descriptions of the laws of Nature that are not inconsistent with observation or other physical laws, but that this doesn't make them "problems" that need to be solved by physicists. (In the same way, even tough there is more than one way to prove the Pythagorean Theorem, the validity of the Pythagorean Theorem ceased to be a "problem" once it was first proven, even though not every means of proving it had been articulated at that point.) 

I also agree that her placement of the phenomena associated with "dark matter" at the top of her list of "good problems" is appropriate. The existence of these phenomena are established by overwhelming evidence and they can only be explained with "new physics" or (at least) a major reinterpretation of existing physics as it is applied today. Further, figuring out the cause of "dark matter phenomena" is likely to have applications that are predictive, in addition to explaining existing knowledge.

Tuesday, January 8, 2019

Earlier Out of Africa Evidence

A jaw bone and teeth found at least 177,000 years ago in what is now Israel appears to be that of a modern human, pushing back the earliest known evidence of modern humans out of Africa by at least 57,000 years. This is much older than the estimated date of the most recent common ancestor (TMRCA) of all extent Eurasians based upon some genetic evidence although other genetic evidence suggests an even earlier date.
Earliest modern humans out of Africa

Recent paleoanthropological studies have suggested that modern humans migrated from Africa as early as the beginning of the Late Pleistocene, 120,000 years ago. Hershkovitz et al.now suggest that early modern humans were already present outside of Africa more than 55,000 years earlier. During excavations of sediments at Mount Carmel, Israel, they found a fossil of a mouth part, a left hemimaxilla, with almost complete dentition.

The sediments contain a series of well-defined hearths and a rich stone-based industry, as well as abundant animal remains. Analysis of the human remains, and dating of the site and the fossil itself, indicate a likely age of at least 177,000 years for the fossil—making it the oldest member of the Homo sapiens clade found outside Africa.

Abstract

To date, the earliest modern human fossils found outside of Africa are dated to around 90,000 to 120,000 years ago at the Levantine sites of Skhul and Qafzeh. A maxilla and associated dentition recently discovered at Misliya Cave, Israel, was dated to 177,000 to 194,000 years ago, suggesting that members of the Homo sapiens clade left Africa earlier than previously thought. This finding changes our view on modern human dispersal and is consistent with recent genetic studies, which have posited the possibility of an earlier dispersal of Homo sapiens around 220,000 years ago. The Misliya maxilla is associated with full-fledged Levallois technology in the Levant, suggesting that the emergence of this technology is linked to the appearance of Homo sapiens in the region, as has been documented in Africa.
Israel Hershkovitz, et al., "The earliest modern humans outside Africa" 359 (6374) Science 456-459 (January 26, 2018) DOI: 10.1126/science.aap8369