Korean, Japanese, Vietnamese, and Cantonese

Korean and Cantonese (a.k.a. Yue Chinese) share some similarities because Cantonese preserves more ancient pronunciations than other Chinese languages, and Korean was influenced by Chinese at a time when these ancient pronunciations were used for words that it borrowed from Chinese. Japanese loan words from Chinese also sound more like Cantonese than other Chinese languages for the same reason. Specifically, Cantonese and these loanwords all have pronunciations that were used by Middle Chinese.

Presumably, then, these loan word pronunciations in Korean and Japanese date to the time period from roughly the 6th to 10th centuries, or perhaps as late as a couple of centuries later, when Middle Chinese was spoken. In the case of Korean, this corresponds to Old Korean. In the case of Japanese, this corresponds to Old Japanese and early Middle Japanese. 

Prior to Old Korean and Old Japanese, which were written with Chinese characters, neither Korean languages or Japanese languages had a written form, and the Chinese loan words were also probably mostly absent. There were three languages or dialects in Korea, before the language of the unified Silla Kingdom that united the southern two-thirds of the peninsula and lead to the extinction of the two sister languages spoken by the kingdoms it conquered. The Proto-Japonic language that preceded Old Japanese probably arrived in Japan from Korea. "Most scholars believe that Japonic was brought to northern Kyushu from the Korean peninsula around 700 to 300 BC by wet-rice farmers of the Yayoi culture and spread throughout the Japanese archipelago, replacing indigenous languages." This was during the Korean Iron Age and prior to the proto-Three Kingdoms period. In this time period:

Gojoseon was the first Korean kingdom, located in the north of the peninsula and Manchuria, later alongside the state of Jin in the south of the peninsula. . . . 

The historical Gojoseon kingdom was first mentioned in the Chinese record in a text called Guanzi, attributed to 7th century BCE. By about the 4th century BC, Gojoseon had developed to the point where its existence was well known in China, and around this time, its capital moved to Pyongyang.

In 194 BC, the King of Gojoseon was overthrown by Wi Man (also known as Wei Man), a Korean-Chinese refugee from the Han vassal state of Yan. Wi Man then established Wiman Joseon. In 128 BC, Nan Lü (南閭), a leader of Ye who was receiving pressure from Wiman Joseon, surrendered to the Han dynasty and became the Canghai Commandery. In 108 BC, the Chinese Han dynasty defeated Wiman Joseon and installed four commanderies in the northern Korean peninsula. . . . 

Around 300 BC, a state called Jin arose in the southern part of the Korean peninsula. Very little is known about Jin, but it established relations with Han China and exported artifacts to the Yayoi of Japan. Around 100 BC, Jin evolved into the Samhan confederacies.

Many smaller states sprang from the former territory of Gojoseon such as Buyeo, Okjeo, Dongye, Goguryeo, and Baekje. The Three Kingdoms refer to Goguryeo, Baekje, and Silla, although Buyeo and the Gaya confederacy existed into the 5th and 6th centuries respectively.

Modern Korean is derived from Middle Korean:

Middle Korean is the period in the history of the Korean language succeeding Old Korean and yielding in 1600 to the Modern period. The boundary between the Old and Middle periods is traditionally identified with the establishment of Goryeo in 918, but some scholars have argued for the time of the Mongol invasions of Korea (mid-13th century). Middle Korean is often divided into Early and Late periods corresponding to Goryeo (until 1392) and Joseon respectively. It is difficult to extract linguistic information from texts of the Early period, which are written using adaptations of Chinese characters. The situation was transformed in 1446 by the introduction of the Hangul alphabet, so that Late Middle Korean provides the pivotal data for the history of Korean.

Given this timing, it would appear that the bulk of Chinese loan words into Korean were received in the Old Korean time period, which coincided with Middle Chinese. And, since the earliest Korean writing is in Chinese characters and dates to about the 6th or 7th centuries, prior to that time, Korean may not have had a written language at all. Since written Chinese is much older than that, it makes sense that Chinese loan words into Korean date to around the same time that Korean started to be written with Chinese characters.

Old Korean (North Korean name: 고대 조선어; South Korean name: 고대 한국어) is the first historically documented stage of the Korean language, typified by the language of the Unified Silla period (668–935).

The boundaries of Old Korean periodization remain in dispute. Some linguists classify the sparsely attested languages of the Three Kingdoms of Korea as variants of Old Korean, while others reserve the term for the language of Silla alone. Old Korean traditionally ends with the fall of Silla in 935. This too has recently been challenged by South Korean linguists who argue for extending the Old Korean period to the mid-thirteenth century, although this new periodization is not yet fully accepted. This article focuses on the language of Silla before the tenth century.

Old Korean is poorly attested. Due to the paucity and poor quality of sources, modern linguists have "little more than a vague outline" of the characteristics of Old Korean. The only surviving literary works are a little more than a dozen vernacular poems called hyangga. Hyangga use hyangchal writing. Other sources include inscriptions on steles and wooden tablets, glosses to Buddhist sutras, and the transcription of personal and place names in works otherwise in Classical Chinese. All methods of Old Korean writing rely on logographic Chinese characters, used to either gloss the meaning or approximate the sound of the Korean words. Thus, the phonetic value of surviving Old Korean texts is opaque. Its phoneme inventory seems to have included fewer consonants but more vowels than Middle Korean. In its typology, it was a subject-object-verb, agglutinative language, like both Middle and Modern Korean. However, Old Korean is thought to have differed from its descendants in certain typological features, including the existence of clausal nominalization and the ability of inflecting verb roots to appear in isolation.

Despite attempts to link the language to the putative Altaic family and especially to the Japonic languages, no links between Old Korean and any non-Koreanic language have been uncontroversially demonstrated. . . . 

For what it is worth, I have almost no doubts about the linguistic relatedness of the Korean and Japanese languages, and I see their connection to at least parts of the larger Altaic family as at least more likely than not. Some scholars suspect that Japanese is a descendants of one of the two pre-Old Korean languages of Korea that have since died.

Old Korean is generally defined as the ancient Koreanic language of the Silla state (BCE 57–CE 936), especially in its Unified period (668–936). Proto-Koreanic, the hypothetical ancestor of the Koreanic languages understood largely through the internal reconstruction of later forms of Korean, is to be distinguished from the actually historically attested language of Old Korean.

Old Korean semantic influence may be present in even the oldest discovered Silla inscription, a Classical Chinese-language stele dated to 441 or 501. Korean syntax and morphemes are visibly attested for the first time in Silla texts of the mid- to late sixth century, and the use of such vernacular elements becomes more extensive by the Unified period.

Initially only one of the Three Kingdoms of Korea, Silla rose to ascendancy in the sixth century under monarchs Beopheung and Jinheung. After another century of conflict, the kings of Silla allied with Tang China to destroy the other two kingdoms—Baekje in 660, and Goguryeo in 668—and to unite the southern two-thirds of the Korean Peninsula under their rule. This political consolidation allowed the language of Silla to become the lingua franca of the peninsula and ultimately drove the languages of Baekje and Goguryeo to extinction, leaving the latter only as substrata in later Korean dialects. Middle Korean, and hence Modern Korean, are thus direct descendants of the Old Korean language of Silla.

Little data on the languages of the other two kingdoms survive, but most linguists agree that both were related to the language of Silla. Opinion differs as to whether to classify the Goguryeo and Baekje languages as Old Korean variants, or as related but independent languages. Lee Ki-Moon and S. Roberts Ramsey argue in 2011 that evidence for mutual intelligibility is insufficient, and that linguists ought to "treat the fragments of the three languages as representing three separate corpora". Earlier in 2000, Ramsey and Iksop Lee note that the three languages are often grouped as Old Korean, but point to "obvious dissimilarities" and identify Sillan as Old Korean "in the truest sense". Nam Pung-hyun and Alexander Vovin, on the other hand, classify the languages of all three kingdoms as regional dialects of Old Korean. Other linguists, such as Lee Seungjae, group the languages of Silla and Baekje together as Old Korean while excluding that of Goguryeo. The LINGUIST List gives Silla as a synonym for Old Korean while acknowledging that the term is "often used to refer to three distinct languages".

In a similar exercise the different stages of the evolution of the Japanese language can be compared to the era when Middle Chinese was spoken. These corresponds to Old Japanese, when Chinese characters were used to make it a written language, and Early Middle Japanese.

Prehistory

Proto-Japonic, the common ancestor of the Japanese and Ryukyuan languages, is thought to have been brought to Japan by settlers coming from the Korean peninsula sometime in the early- to mid-4th century BC (the Yayoi period), replacing the languages of the original Jōmon inhabitants, including the ancestor of the modern Ainu language. Because writing had yet to be introduced from China, there is no direct evidence, and anything that can be discerned about this period must be based on internal reconstruction from Old Japanese, or comparison with the Ryukyuan languages and Japanese dialects.

Old Japanese

The Chinese writing system was imported to Japan from Baekje around the start of the fifth century, alongside Buddhism. The earliest texts were written in Classical Chinese, although some of these were likely intended to be read as Japanese using the kanbun method, and show influences of Japanese grammar such as Japanese word order. The earliest text, the Kojiki, dates to the early eighth century, and was written entirely in Chinese characters, which are used to represent, at different times, Chinese, kanbun, and Old Japanese. As in other texts from this period, the Old Japanese sections are written in Man'yōgana, which uses kanji for their phonetic as well as semantic values.

Based on the Man'yōgana system, Old Japanese can be reconstructed as having 88 distinct morae. Texts written with Man'yōgana use two different sets of kanji for each of the morae now pronounced き (ki), ひ (hi), み (mi), け (ke), へ (he), め (me), こ (ko), そ (so), と (to), の (no), も (mo), よ (yo) and ろ (ro).[7] (The Kojiki has 88, but all later texts have 87. The distinction between mo1 and mo2 apparently was lost immediately following its composition.) This set of morae shrank to 67 in Early Middle Japanese, though some were added through Chinese influence. Man'yōgana also has a symbol for /je/, which merges with /e/ before the end of the period.

Several fossilizations of Old Japanese grammatical elements remain in the modern language – the genitive particle tsu (superseded by modern no) is preserved in words such as matsuge ("eyelash", lit. "hair of the eye"); modern mieru ("to be visible") and kikoeru ("to be audible") retain a mediopassive suffix -yu(ru) (kikoyu → kikoyuru (the attributive form, which slowly replaced the plain form starting in the late Heian period) → kikoeru (all verbs with the shimo-nidan conjugation pattern underwent this same shift in Early Modern Japanese)); and the genitive particle ga remains in intentionally archaic speech.

Early Middle Japanese

Early Middle Japanese is the Japanese of the Heian period, from 794 to 1185. It formed the basis for the literary standard of Classical Japanese, which remained in common use until the early 20th century.

During this time, Japanese underwent numerous phonological developments, in many cases instigated by an influx of Chinese loanwords. These included phonemic length distinction for both consonants and vowels, palatal consonants (e.g. kya) and labial consonant clusters (e.g. kwa), and closed syllables. This had the effect of changing Japanese into a mora-timed language.

Late Middle Japanese

Late Middle Japanese covers the years from 1185 to 1600, and is normally divided into two sections, roughly equivalent to the Kamakura period and the Muromachi period, respectively. The later forms of Late Middle Japanese are the first to be described by non-native sources, in this case the Jesuit and Franciscan missionaries; and thus there is better documentation of Late Middle Japanese phonology than for previous forms (for instance, the Arte da Lingoa de Iapam). Among other sound changes, the sequence /au/ merges to /ɔː/, in contrast with /oː/; /p/ is reintroduced from Chinese; and /we/ merges with /je/. Some forms rather more familiar to Modern Japanese speakers begin to appear – the continuative ending -te begins to reduce onto the verb (e.g. yonde for earlier yomite), the -k- in the final mora of adjectives drops out (shiroi for earlier shiroki); and some forms exist where modern standard Japanese has retained the earlier form (e.g. hayaku > hayau > hayɔɔ, where modern Japanese just has hayaku, though the alternative form is preserved in the standard greeting o-hayō gozaimasu "good morning"; this ending is also seen in o-medetō "congratulations", from medetaku).

Late Middle Japanese has the first loanwords from European languages – now-common words borrowed into Japanese in this period include pan ("bread") and tabako ("tobacco", now "cigarette"), both from Portuguese.

Modern Japanese

Modern Japanese is considered to begin with the Edo period (which spanned from 1603 to 1867). Since Old Japanese, the de facto standard Japanese had been the Kansai dialect, especially that of Kyoto. However, during the Edo period, Edo (now Tokyo) developed into the largest city in Japan, and the Edo-area dialect became standard Japanese. Since the end of Japan's self-imposed isolation in 1853, the flow of loanwords from European languages has increased significantly. The period since 1945 has seen many words borrowed from other languages—such as German, Portuguese and English. Many English loan words especially relate to technology—for example, pasokon (short for "personal computer"), intānetto ("internet"), and kamera ("camera"). Due to the large quantity of English loanwords, modern Japanese has developed a distinction between [tɕi] and [ti], and [dʑi] and [di], with the latter in each pair only found in loanwords. . . . 

The language experienced a massive influx of Sino-Japanese vocabulary after the introduction of Buddhism in the 6th century and peaking with the wholesale importation of Chinese culture in the 8th and the 9th centuries. The loanwords now account for about half the lexicon. They also affected the sound system of the language by adding compound vowels, syllable-final nasals, and geminate consonants, which became separate morae. Most of the changes in morphology and syntax reflected in the modern language took place during the Late Middle Japanese period (13th to 16th centuries). . . . 

There is fragmentary evidence suggesting that now-extinct Japonic languages were spoken in the central and southern parts of the Korean peninsula. Vovin calls these languages Peninsular Japonic and groups Japanese and Ryukyuan as Insular Japonic.

The most-cited evidence comes from chapter 37 of the Samguk sagi (compiled in 1145), which contains a list of pronunciations and meanings of placenames in the former kingdom of Goguryeo. As the pronunciations are given using Chinese characters, they are difficult to interpret, but several of those from central Korea, in the area south of the Han River captured from Baekje in the 5th century, seem to correspond to Japonic words. Scholars differ on whether they represent the language of Goguryeo or the people that it conquered.

Traces from the south of the peninsula are very sparse: The Silla placenames listed in Chapter 34 of the Samguk sagi are not glossed, but many of them can be explained as Japonic words.

• Alexander Vovin proposes Japonic etymologies for two of four Baekje words given in the Book of Liang (635).
• A single word is explicitly attributed to the language of the southern Gaya confederacy, in Chapter 44 of the Samguk sagi. It is a word for 'gate' and appears in a similar form to the Old Japanese word to2, with the same meaning.
• Vovin suggests that the ancient name for the kingdom of Tamna on Jeju Island, tammura, may have a Japonic etymology tani mura 'valley settlement' or tami mura 'people's settlement'. . . . 

According to Shirō Hattori, more attempts have been made to link Japanese with other language families than for any other language. None of the attempts has succeeded in demonstrating a common descent for Japonic and any other language family.

The most systematic comparisons have involved Korean, which has a very similar grammatical structure to Japonic languages. Samuel Elmo Martin, John Whitman, and others have proposed hundreds of possible cognates, with sound correspondences. However, Alexander Vovin points out that Old Japanese contains several pairs of words of similar meaning in which one word matches a Korean form, and the other is also found in Ryukyuan and Eastern Old Japanese, suggesting that the former is an early loan from Korean. He suggests that to eliminate such early loans, Old Japanese morphemes should not be assigned a Japonic origin unless they are also attested in Southern Ryukyuan or Eastern Old Japanese. That procedure leaves fewer than a dozen possible cognates, which may have been borrowed by Korean from Peninsular Japonic.

There was also contemporaneous Chinese linguistic influence in Vietnam, with all three waves of Chinese loan words more or less corresponding to the Tang Dynasty of China:

During the Tang dynasty (618–907), Chinese writing, language and culture were imported wholesale into Vietnam, Korea and Japan. Scholars in those countries wrote in Literary Chinese and were thoroughly familiar with the Chinese classics, which they read aloud in systematic local approximations of Middle Chinese. With those pronunciations, Chinese words entered Vietnamese, Korean and Japanese in huge numbers.

The plains of northern Vietnam were under Chinese control for most of the period from 111 BC to AD 938. After independence, the country adopted Literary Chinese as the language of administration and scholarship. As a result, there are several layers of Chinese loanwords in Vietnamese. The oldest loans, roughly 400 words dating from the Eastern Han, have been fully assimilated and are treated as native Vietnamese words. Sino-Vietnamese proper dates to the early Tang dynasty, when the spread of Chinese rime dictionaries and other literature resulted in the wholesale importation of the Chinese lexicon.

Isolated Chinese words also began to enter Korean from the 1st century BC, but the main influx occurred in the 7th and 8th centuries after the unification of the peninsula by Silla. The flow of Chinese words into Korean became overwhelming after the establishment of civil service examinations in 958.

Japanese has two well-preserved layers and a third that is also significant: 

• Go-on readings date to the introduction of Buddhism to Japan from Korea in the 6th century. Based on the name, they are widely believed to reflect pronunciations of Jiankang in the lower Yangtze area during the late Northern and Southern dynasties period. However, this cannot be substantiated, and Go-on appears to reflect an amalgam of different Chinese varieties transmitted through Korea.
• Kan-on readings are believed to reflect the standard pronunciation of the Tang period, as used in the cities of Chang'an and Luoyang. It was transmitted directly by Japanese who studied in China.
• Tōsō-on readings were introduced by followers of Zen Buddhism in the 14th century and are thought to be based on the speech of Hangzhou. . . . 

In contrast, vocabulary of Chinese origin in Thai, including most of the basic numerals, was borrowed over a range of periods from the Han (or earlier) to the Tang.

Since the pioneering work of Bernhard Karlgren, these bodies of pronunciations have been used together with modern varieties of Chinese in attempts to reconstruct the sounds of Middle Chinese. They provide such broad and systematic coverage that the linguist Samuel Martin called them "Sino-Xenic dialects", treating them as parallel branches with the native Chinese dialects. The foreign pronunciations sometimes retain distinctions lost in all the modern Chinese varieties, as in the case of the chongniu distinction found in Middle Chinese rime dictionaries. Similarly, the distinction between grades III and IV made by the Late Middle Chinese rime tables has disappeared in most modern varieties, but in kan-on, grade IV is represented by the Old Japanese vowels i1 and e1 while grade III is represented by i2 and e2.

Vietnamese, Korean and Japanese scholars also later each adapted the Chinese script to write their languages, using Chinese characters both for borrowed and native vocabulary. Thus, in the Japanese script, Chinese characters may have both Sino-Japanese readings (on'yomi) and native readings (kun'yomi). Similarly, in the chữ Nôm script used for Vietnamese until the early 20th century, some Chinese characters could represent both a Sino-Vietnamese word and a native Vietnamese word with similar meaning or sound to the Chinese word, but would often be marked with a diacritic when the native reading was intended. However, in the Korean mixed script, Chinese characters (hanja) are only used for Sino-Korean words. The character-based Vietnamese and Korean scripts have since been replaced by the Vietnamese alphabet and hangul respectively, although Korean does still use Hanja to an extent.

The Tang Dynasty was a big deal in the history of China (and incidentally, coincided with the early Islamic Empire and the Migration Period in the West):

The Tang empire in 661, at its greatest extent.

The Tang dynasty (/tɑːŋ/, [tʰǎŋ]; Chinese: 唐朝), or the Tang Empire, was an imperial dynasty of China that ruled from 618 to 907, with an interregnum between 690 and 705. It was preceded by the Sui dynasty and followed by the Five Dynasties and Ten Kingdoms period. Historians generally regard the Tang as a high point in Chinese civilization, and a golden age of cosmopolitan culture. Tang territory, acquired through the military campaigns of its early rulers, rivaled that of the Han dynasty.

The Li family founded the dynasty after taking advantage of a period of Sui decline and precipitating their final collapse, in turn inaugurating a period of progress and stability in the first half of the dynasty's rule. The dynasty was formally interrupted during 690–705 when Empress Wu Zetian seized the throne, proclaiming the Wu Zhou dynasty and becoming the only legitimate Chinese empress regnant. The devastating An Lushan Rebellion (755–763) led to the decline of central authority in the dynasty's latter half. Like the previous Sui dynasty, the Tang maintained a civil-service system by recruiting scholar-officials through standardized examinations and recommendations to office. The rise of regional military governors known as jiedushi during the 9th century undermined this civil order. The dynasty and central government went into decline by the latter half of the 9th century; agrarian rebellions resulted in mass population loss and displacement, widespread poverty, and further government dysfunction that ultimately ended the dynasty in 907.

The Tang capital at Chang'an (present-day Xi'an) was the world's most populous city for much of the dynasty's existence. Two censuses of the 7th and 8th centuries estimated the empire's population at about 50 million people, which grew to an estimated 80 million by the dynasty's end. From its numerous subjects, the dynasty raised professional and conscripted armies of hundreds of thousands of troops to contend with nomadic powers for control of Inner Asia and the lucrative trade-routes along the Silk Road. Far-flung kingdoms and states paid tribute to the Tang court, while the Tang also indirectly controlled several regions through a protectorate system. In addition to its political hegemony, the Tang exerted a powerful cultural influence over neighboring East Asian nations such as Japan and Korea.

Cantonese preservation of ancient Chinese pronunciations is mentioned, for example, by the Encyclopedia Britannica, which states that:

Cantonese preserves more features of Ancient Chinese than do the other major Chinese languages; its various dialects retain most of the final consonants of the older language and have at least six tones, in contrast to the four tones of Modern Standard Chinese, to distinguish meaning between words or word elements that have the same arrangement of consonant and vowel sounds. The language has fewer initial consonants than Modern Standard Chinese and about twice as many distinctively different syllables. 

According to Wikipedia, per the link above:

Cantonese is the traditional prestige variety of Yue Chinese, a Sinitic language belonging to the Sino-Tibetan language family. It originated in the city of Guangzhou (formerly known as Canton) and its surrounding Pearl River Delta [ed. a.k.a. the Guangdong–Hong Kong–Macao Greater Bay Area].

Cantonese is regarded as an integral and inextricable component of the cultural identity of its native speakers across a vast expanse of southeastern China, Hong Kong, and Macau, as well as in overseas communities. In mainland China, Cantonese is the lingua franca of the Chinese province of Guangdong (being the majority language of the Pearl River Delta) and neighbouring areas such as Guangxi. It is also the dominant and co-official language of Hong Kong and Macau. Furthermore, Cantonese is widely spoken among overseas Chinese in Southeast Asia (most notably in Vietnam and Malaysia, as well as in Singapore and Cambodia to a lesser extent) and the Western world.

Despite the considerable overlap in vocabulary between Cantonese and Mandarin, as well as other varieties of Chinese, these Sinitic languages are not mutually intelligible. This is due to a combination of factors, including phonological differences and variations in grammar and vocabulary.

 

Thus, the similarity exists despite the significant geographic distance between the areas where Cantonese has its origins and is most widely spoken on one hand, and Korea and Japan on the other, and despite the fact that less similar topolects of Chinese exist between these two regions.

The Chinese language began to be spoken on a widespread basis in the Pearl River Delta region starting around 214 BCE when ethically Han Chinese people began to migrate to the region in large numbers after it was conquered by the Qin Dynasty. According to the same link:

Successive waves of immigration followed at times of upheaval in Northern and Central China, such as the collapse of the Han, Tang and Song dynasties. The most popular route was via the Xiang River, which the Qin had connected to the Li River by the Lingqu Canal, and then into the valley of the Xi Jiang. A secondary route followed the Gan River and then the Bei Jiang into eastern Guangdong. Yue-speakers were later joined by Hakka speakers following the North River route, and Min speakers arriving by sea.

After the fall of Qin, the Lingnan area was part of the independent state of Nanyue for about a century, before being incorporated into the Han empire in 111 BC. After the Tang dynasty collapsed, much of the area became part of the state of Southern Han, one of the longest-lived states of the Five Dynasties and Ten Kingdoms, between 917 and 971.

Large waves of Chinese migration throughout succeeding Chinese dynasties assimilated huge numbers of Yue aborigines, with the result that today's Southern Han Chinese Yue-speaking population is descended from both groups. 

The colloquial layers of Yue varieties contain elements influenced by the Tai languages formerly spoken widely in the area and still spoken by people such as the Zhuang and Dong.

The port city of Guangzhou lies in the middle of Pearl River Delta, with access to the interior via the Xi, Bei, and Dong rivers, which all converge at the delta. It has been the economic centre of the Lingnan region since Qin times, when it was an important shipbuilding centre. By 660, it was the largest port in China, part of a trade network stretching as far as Arabia. During the Southern Song, it also became the cultural centre of the region. Like many other Chinese varieties it developed a distinct literary layer associated with the local tradition of reading the classics. The Guangzhou dialect (Cantonese) was used in the popular Yuèōu, Mùyú and Nányīn folksong genres, as well as Cantonese opera. There was also a small amount of vernacular literature, written with Chinese characters extended with a number of non-traditional characters for Cantonese words.

Guangzhou became the centre of rapidly expanding foreign trade after the maritime ban was lifted, with the British East India Company establishing a chamber of commerce in the city in 1715. The ancestors of most of the Han Chinese population of Hong Kong came from Guangzhou after the territory was ceded to Britain in 1842. As a result, Hong Kong Cantonese, the most widely spoken language in Hong Kong and Macau, is an offshoot of the Guangzhou dialect. . . . 

Yue varieties are among the most conservative of Chinese varieties regarding the final consonants and tonal categories of Middle Chinese, so that the rhymes of Tang poetry are clearer in Yue dialects than elsewhere. However they have lost several distinctions in the initial consonants and medial vowels that other Chinese varieties have retained.

Initials and medials

In addition to aspirated and unaspirated voiceless initials, Middle Chinese had a series of voiced initials, but voicing has been lost in Yue and most other modern Chinese varieties apart from Wu and Old Xiang. In the Guangfu, Siyi and Gao–Yang subgroups, these initials have yielded aspirated consonants in the level and rising tones, and unaspirated consonants in the departing and entering tones. These initials are uniformly unaspirated in Gou–Lou varieties and uniformly aspirated in Wu–Hua.

In many Yue varieties, including Cantonese, Middle Chinese /kʰ/ has become [h] or [f] in most words; in Taishanese, /tʰ/ has also changed to [h], for example, in the native name of the dialect, "Hoisan". In Siyi and eastern Gao–Yang, Middle Chinese /s/ has become a voiceless lateral fricative [ɬ].

Most Yue varieties have merged the Middle Chinese retroflex sibilants with the alveolar sibilants, in contrast with Mandarin dialects, which have generally maintained the distinction. For example, the words 將; jiāng and 張; zhāng are distinguished in Mandarin, but in modern Cantonese they are both pronounced as jēung.

Many Mandarin varieties, including the Beijing dialect, have a third sibilant series, formed through a merger of palatalized alveolar sibilants and velars, but this is a recent innovation, which has not affected Yue and other Chinese varieties. For example, 晶, 精, 經 and 京 are all pronounced as jīng in Mandarin, but in Cantonese the first pair is pronounced jīng, while the second pair is pronounced gīng. The earlier pronunciation is reflected in historical Mandarin romanizations, such as "Peking" for Beijing, "Kiangsi" for Jiangxi, and "Tientsin" for Tianjin.

Some Yue speakers, such as many Hong Kong Cantonese speakers born after World War II, merge /n/ with /l/, but Taishanese and most other Yue varieties preserve the distinction. Younger Cantonese speakers also tend not to distinguish between /ŋ/ and the zero initial, though this distinction is retained in most Yue dialects. Yue varieties retain the initial /m/ in words where Late Middle Chinese shows a shift to a labiodental consonant, realized in most Northern varieties of Chinese as [w]. Nasals can be independent syllables in Yue words, e.g. Cantonese 五; ńgh; 'five', and 唔; m̀h; 'not', although Middle Chinese did not have syllables of this type.

In most Yue varieties (except for Tengxian), the rounded medial /w/ has merged with the following vowel to form a monophthong, except after velar initials. In most analyses velars followed by /w/ are treated as labio-velars.

Most Yue varieties have retained the Middle Chinese palatal medial, but in Cantonese it has also been lost to monophthongization, yielding a variety of vowels.

Final consonants and tones

Middle Chinese syllables could end with glides /j/ or /w/, nasals /m/, /n/ or /ŋ/, or stops /p/, /t/ or /k/. Syllables with vocalic or nasal endings could occur with one of three tonal contours, called 平; 'level', 上; 'rising', or 去; 'departing'. Syllables with final stops were traditionally treated as a fourth tone category, the entering tone 入; rù, because the stops were distributed in the same way as the corresponding final nasals.

While northern and central varieties have lost some of the Middle Chinese final consonants, they are retained by most southern Chinese varieties, though sometimes affected by sound shifts. They are most faithfully preserved in Yue dialects. Final stops have disappeared entirely in most Mandarin dialects, including the Beijing-based standard, with the syllables distributed across the other tones. For example, the characters 裔, 屹, 藝, 憶, 譯, 懿, 肄, 翳, 邑, and 佚 are all pronounced yì in Mandarin, but they are all distinct in Yue: in Cantonese, yeuih, ngaht, ngaih, yīk, yihk, yi, yih, ai, yāp, and yaht, respectively.

Similarly, in Mandarin dialects the Middle Chinese final /m/ has merged with /n/, but the distinction is maintained in southern varieties of Chinese such as Hakka, Min and Yue. For example, Cantonese has 譚; taahm and 壇; tàahn versus Mandarin tán, 鹽; yìhm and 言; yìhn versus Mandarin yán, 添; tìm and 天; tìn versus Mandarin tiān, and 含; hàhm and 寒; hòhn versus Mandarin hán.

Middle Chinese is described in contemporary dictionaries as having four tones, where the fourth category, the entering tone, consists of syllables with final stops. Many modern Chinese varieties contain traces of a split of each of these four tones into two registers, an upper or yīn register from voiceless initials and a lower or yáng register from voiced initials. Most Mandarin dialects retain the register distinction only in the level tone, yielding the first and second tones of the standard language (corresponding to the first and fourth tones in Cantonese), but have merged several of the other categories. Most Yue dialects have retained all eight categories, with a further split of the upper entering tone conditioned by vowel length, as also found in neighbouring Tai dialects. A few dialects spoken in Guangxi, such as the Bobai dialect, have also split the lower entering tone.

Middle Chinese, meanwhile, is first attested around 500 CE by Shen Yue:

Middle Chinese (formerly known as Ancient Chinese) or the Qieyun system (QYS) is the historical variety of Chinese recorded in the Qieyun, a rime dictionary first published in 601 and followed by several revised and expanded editions. The Swedish linguist Bernhard Karlgren believed that the dictionary recorded a speech standard of the capital Chang'an of the Sui and Tang dynasties. However, based on the preface of the Qieyun, most scholars now believe that it records a compromise between northern and southern reading and poetic traditions from the late Northern and Southern dynasties period. This composite system contains important information for the reconstruction of the preceding system of Old Chinese phonology (early 1st millennium BC).

The fanqie method used to indicate pronunciation in these dictionaries, though an improvement on earlier methods, proved awkward in practice. The mid-12th-century Yunjing and other rime tables incorporate a more sophisticated and convenient analysis of the Qieyun phonology. The rime tables attest to a number of sound changes that had occurred over the centuries following the publication of the Qieyun. Linguists sometimes refer to the system of the Qieyun as Early Middle Chinese and the variant revealed by the rime tables as Late Middle Chinese.

The dictionaries and tables describe pronunciations in relative terms, but do not give their actual sounds. Karlgren was the first to attempt a reconstruction of the sounds of Middle Chinese, comparing its categories with modern varieties of Chinese and the Sino-Xenic pronunciations used in the reading traditions of neighbouring countries. Several other scholars have produced their own reconstructions using similar methods.

The Qieyun system is often used as a framework for Chinese dialectology. With the exception of Min varieties, which show independent developments from Old Chinese, modern Chinese varieties can be largely treated as divergent developments from Middle Chinese. The study of Middle Chinese also provides for a better understanding and analysis of Classical Chinese poetry, such as the study of Tang poetry. 

. . . 

The tone system of Middle Chinese is strikingly similar to those of its neighbours in the Mainland Southeast Asia linguistic area—proto-Hmong–Mien, proto-Tai and early Vietnamese—none of which is genetically related to Chinese. Moreover, the earliest strata of loans display a regular correspondence between tonal categories in the different languages. In 1954, André-Georges Haudricourt showed that Vietnamese counterparts of the rising and departing tones corresponded to final /ʔ/ and /s/, respectively, in other (atonal) Austroasiatic languages. He thus argued that the Austroasiatic proto-language had been atonal, and that the development of tones in Vietnamese had been conditioned by these consonants, which had subsequently disappeared, a process now known as tonogenesis. Haudricourt further proposed that tone in the other languages, including Middle Chinese, had a similar origin. 

Other scholars have since uncovered transcriptional and other evidence for these consonants in early forms of Chinese, and many linguists now believe that Old Chinese was atonal.

Around the end of the first millennium AD, Middle Chinese and the southeast Asian languages experienced a phonemic split of their tone categories. Syllables with voiced initials tended to be pronounced with a lower pitch, and by the late Tang dynasty, each of the tones had split into two registers conditioned by the initials, known as the "upper" and "lower". When voicing was lost in most varieties (except in the Wu and Old Xiang groups and some Gan dialects), this distinction became phonemic, yielding up to eight tonal categories, with a six-way contrast in unchecked syllables and a two-way contrast in checked syllables. Cantonese maintains these tones and has developed an additional distinction in checked syllables, resulting in a total of nine tonal categories. However, most varieties have fewer tonal distinctions. For example, in Mandarin dialects the lower rising category merged with the departing category to form the modern falling tone, leaving a system of four tones. Furthermore, final stop consonants disappeared in most Mandarin dialects, and such syllables were reassigned to one of the other four tones.

Changes from Old to Modern Chinese

Middle Chinese had a structure similar to many modern varieties, especially conservative ones like Cantonese, with largely monosyllabic words, little or no derivational morphology, three tones, and a syllable structure consisting of initial consonant, glide, main vowel and final consonant, with a large number of initial consonants and a fairly small number of final consonants. Without counting the glide, no clusters could occur at the beginning or end of a syllable.

Old Chinese, on the other hand, had a significantly different structure. There were no tones, a smaller imbalance between possible initial and final consonants, and many initial and final clusters. There was a well-developed system of derivational and possibly inflectional morphology, formed using consonants added onto the beginning or end of a syllable. The system is similar to the system reconstructed for Proto-Sino-Tibetan and still visible, for example, in Classical Tibetan; it is also largely similar to the system that occurs in the more conservative Austroasiatic languages, such as modern Khmer.

The main changes leading to the modern varieties have been a reduction in the number of consonants and vowels and a corresponding increase in the number of tones (typically through a Pan-East-Asiatic tone split that doubled the number of tones and eliminated the distinction between voiced and unvoiced consonants). That has led to a gradual decrease in the number of possible syllables. Standard Mandarin has only about 1,300 possible syllables, and many other varieties of Chinese even fewer (for example, modern Shanghainese has been reported to have only about 700 syllables). The result in Mandarin, for example, has been the proliferation of the number of two-syllable compound words, which have steadily replaced former monosyllabic words; most words in Standard Mandarin now have two syllables.

Middle Chinese continues to be attested through at least 1150 CE. Old Chinese meanwhile, is much older:

Old Chinese, also called Archaic Chinese in older works, is the oldest attested stage of Chinese, and the ancestor of all modern varieties of Chinese. The earliest examples of Chinese are divinatory inscriptions on oracle bones from around 1250 BC, in the Late Shang period. Bronze inscriptions became plentiful during the following Zhou dynasty [ed. 1046 BCE to 256 BCE]. The latter part of the Zhou period saw a flowering of literature, including classical works such as the Analects, the Mencius, and the Zuo Zhuan. These works served as models for Literary Chinese (or Classical Chinese), which remained the written standard until the early twentieth century, thus preserving the vocabulary and grammar of late Old Chinese.

The transition from Middle Chinese to modern Chinese topolects appears to date from sometime between the 10th and 13th centuries.

After the fall of the Northern Song dynasty and subsequent reign of the Jurchen Jin and Mongol Yuan dynasties in northern China, a common speech (now called Old Mandarin) developed based on the dialects of the North China Plain around the capital. The 1324 Zhongyuan Yinyun was a dictionary that codified the rhyming conventions of new sanqu verse form in this language. Together with the slightly later Menggu Ziyun, this dictionary describes a language with many of the features characteristic of modern Mandarin dialects.

Up to the early 20th century, most Chinese people only spoke their local variety. Thus, as a practical measure, officials of the Ming and Qing dynasties carried out the administration of the empire using a common language based on Mandarin varieties, known as 官话; 官話; Guānhuà; 'language of officials'. For most of this period, this language was a koiné based on dialects spoken in the Nanjing area, though not identical to any single dialect. By the middle of the 19th century, the Beijing dialect had become dominant and was essential for any business with the imperial court.

In the 1930s, a standard national language (国语; 國語; Guóyǔ), was adopted. After much dispute between proponents of northern and southern dialects and an abortive attempt at an artificial pronunciation, the National Language Unification Commission finally settled on the Beijing dialect in 1932. The People's Republic founded in 1949 retained this standard but renamed it 普通话; 普通話; pǔtōnghuà; 'common speech'. The national language is now used in education, the media, and formal situations in both mainland China and Taiwan.

In Hong Kong and Macau, Cantonese is the dominant spoken language due to cultural influence from Guangdong immigrants and colonial-era policies, and is used in education, media, formal speech, and everyday life—though Mandarin is increasingly taught in schools due to the mainland's growing influence.

Influence

Historically, the Chinese language has spread to its neighbors through a variety of means. Northern Vietnam was incorporated into the Han dynasty (202 BCE – 220 CE) in 111 BCE, marking the beginning of a period of Chinese control that ran almost continuously for a millennium. The Four Commanderies of Han were established in northern Korea in the 1st century BCE but disintegrated in the following centuries. Chinese Buddhism spread over East Asia between the 2nd and 5th centuries CE, and with it the study of scriptures and literature in Literary Chinese. Later, strong central governments modeled on Chinese institutions were established in Korea, Japan, and Vietnam, with Literary Chinese serving as the language of administration and scholarship, a position it would retain until the late 19th century in Korea and (to a lesser extent) Japan, and the early 20th century in Vietnam. Scholars from different lands could communicate, albeit only in writing, using Literary Chinese.

Although they used Chinese solely for written communication, each country had its own tradition of reading texts aloud using what are known as Sino-Xenic pronunciations. Chinese words with these pronunciations were also extensively imported into the Korean, Japanese and Vietnamese languages, and today comprise over half of their vocabularies. This massive influx led to changes in the phonological structure of the languages, contributing to the development of moraic structure in Japanese and the disruption of vowel harmony in Korean.

Borrowed Chinese morphemes have been used extensively in all these languages to coin compound words for new concepts, in a similar way to the use of Latin and Ancient Greek roots in European languages. Many new compounds, or new meanings for old phrases, were created in the late 19th and early 20th centuries to name Western concepts and artifacts. These coinages, written in shared Chinese characters, have then been borrowed freely between languages. They have even been accepted into Chinese, a language usually resistant to loanwords, because their foreign origin was hidden by their written form. Often different compounds for the same concept were in circulation for some time before a winner emerged, and sometimes the final choice differed between countries. The proportion of vocabulary of Chinese origin thus tends to be greater in technical, abstract, or formal language. For example, in Japan, Sino-Japanese words account for about 35% of the words in entertainment magazines, over half the words in newspapers, and 60% of the words in science magazines.

Vietnam, Korea, and Japan each developed writing systems for their own languages, initially based on Chinese characters, but later replaced with the hangul alphabet for Korean and supplemented with kana syllabaries for Japanese, while Vietnamese continued to be written with the complex chữ Nôm script. However, these were limited to popular literature until the late 19th century. Today Japanese is written with a composite script using both Chinese characters called kanji, and kana. Korean is written exclusively with hangul in North Korea, although knowledge of the supplementary Chinese characters called hanja is still required, and hanja are increasingly rarely used in South Korea. As a result of its historical colonization by France, Vietnamese now uses the Latin-based Vietnamese alphabet.

Why Is Cantonese linguistically conservative?

The Sino-Tibetan language family has its origins in Northern China, and not Southern China. Prior to the arrival of the Han Chinese in 214 BCE, languages belonging the Thai language family thrived where Cantonese is now spoken. Other language families now spoken mostly in Southeast Asia also had their origins in Southern China. 

Presumably the preservation of ancient pronunciations in Cantonese reflects the general linguistic principle the historic features of languages tend to be more strongly preserved on frontiers of a language's range, than near the core of its range. See also Appalachian English (which is the modern English dialect closest to Shakespearian English), New Mexican Spanish (which is the only place that some archaic features of the Spanish language have survived), and the Icelandic language (which is closest to Old Norse, the Germanic proto-language).

The Chinese Min languages, which have some features that predate Middle Chinese, are likewise Chinese languages that developed on the frontier of the range of Chinese languages.

Many Min languages have retained notable features of the Old Chinese language, and there is linguistic evidence that not all Min varieties are directly descended from Middle Chinese of the Sui–Tang dynasties. Min languages are believed to have a significant linguistic substrate from the languages of the inhabitants of the region before its sinicization. . . .

The Min homeland of Fujian was opened to Han Chinese settlement by the defeat of the Minyue state by the armies of Emperor Wu of Han in 110 BC. The area features rugged mountainous terrain, with short rivers that flow into the South China Sea. Most subsequent migration from north to south China passed through the valleys of the Xiang and Gan rivers to the west, so that Min varieties have experienced less northern influence than other southern groups. As a result, whereas most varieties of Chinese can be treated as derived from Middle Chinese—the language described by rhyme dictionaries such as the Qieyun (601 AD)—Min varieties contain traces of older distinctions. Linguists estimate that the oldest layers of Min dialects diverged from the rest of Chinese around the time of the Han dynasty. However, significant waves of migration from the North China Plain occurred: 

• The Uprising of the Five Barbarians during the Jin dynasty, particularly the Disaster of Yongjia in 311 AD, caused a tide of immigration to the south.
• In 669, Chen Zheng and his son Chen Yuanguang from Gushi County in Henan set up a regional administration in Fujian to suppress an insurrection by the She people.
• Wang Chao was appointed governor of Fujian in 893, near the end of the Tang dynasty, and brought tens of thousands of troops from Henan. In 909, following the fall of the Tang dynasty, his son Wang Shenzhi founded the Min Kingdom, one of the Ten Kingdoms in the Five Dynasties and Ten Kingdoms period.

Jerry Norman identifies four main layers in the vocabulary of modern Min varieties: 

1. A non-Chinese substratum from the original languages of Minyue, which Norman and Mei Tsu-lin believe were Austroasiatic.
2. The earliest Chinese layer, brought to Fujian by settlers from Zhejiang to the north during the Han dynasty (compare Eastern Han Chinese).
3. A layer from the Northern and Southern dynasties period, which is largely consistent with the phonology of the Qieyun dictionary (Early Middle Chinese).
4. A literary layer based on the koiné of Chang'an, the capital of the Tang dynasty (Late Middle Chinese).

Laurent Sagart (2008) disagrees with Norman and Mei Tsu-lin's analysis of an Austroasiatic substratum in Min. The hypothesis proposed by Jerry Norman and Mei Tsu-lin arguing for an Austroasiatic homeland along the middle Yangtze has been largely abandoned in most circles and left unsupported by the majority of Austroasiatic specialists. Rather, recent movements of analyzing archeological evidence, posit an Austronesian layer, rather than an Austroasiatic one.

As a footnote, I have argued repeatedly that the highly divergent features of the Anatolian language relative to the time when these languages are first attested and when the first archaeological evidence of Indo-European cultural litmus tests in Anatolia appear, is due to language contact with languages such as the pre-Hittite Hattic language which is very different from the substrate Indo-European languages of Europe. 

But another possibility is that the Anatolian languages preserved archaic features of the language family because they were located at a language frontier of the Indo-European linguistic range. Again, not because they have so much more time depth than the Indo-European languages of Europe, but because they were isolated on the frontier from developments in the Indo-European linguistic community elsewhere, which were more connected to each other, that led those languages to collectively evolve in similar ways.

SUSY And String Theory Advocates Half-Admit Their Problem

So close, and yet so far. The goal posts have been moved again. SUSY is no longer well-motivated (and with it SUSY WIMPs as dark matter candidates are also no longer well-motivated). 

The non-detection of weak scale SUSY is also dragging string theory down with it. 

The signals hypothesized would be dubious and subject to varying interpretations even in the unlikely even that they appeared.

Experimental searches for supersymmetry (SUSY) are entering a new era. The failure to observe signals of sparticle production at the Large Hadron Collider (LHC) has eroded the central motivation for SUSY breaking at the weak scale. 

However, String Theory requires SUSY at the fundamental scale M(s) and hence SUSY could be broken at some high scale below M(s). Actually, if this were the case, the lack of experimental evidence for low-energy SUSY could have been anticipated, because most stringy models with high-scale SUSY breaking predict that sparticles would start popping up above about 10 TeV, well beyond the reach of current LHC experiments. 

We show that using next generation LHC experiments currently envisioned for the Forward Physics Facility (FPF) we could search for signals of neutrino-modulino oscillations to probe models with string scale in the grand unification region and SUSY breaking driven by sequestered gravity in gauge mediation. This is possible because of the unprecedented flux of neutrinos to be produced as secondary products in LHC collisions during the high-luminosity era and the capability of FPF experiments to detect and identify their flavors.

Luis A. Anchordoqui, Ignatios Antoniadis, Karim Benakli, Jules Cunat, Dieter Lust, "SUSY at the FPF", arXiv:2410.16342 (October 21, 2024).

Ethiopian Genetics

Razib Khan has a new piece out on Ethiopian genetics in which he analyzes a sample of modern whole genomes and compares those from Ethiopia with those from elsewhere.

Bottom line: Ethiopian genetics are distinct both from sub-Saharan Bantus, Pygmies and Khoi-San, and from the people of the Levant and Southern Europe.

Standardized genetic distance from Ethiopia’s cultural and historically dominant Amhara people.

In a four population ancestry analysis model, Ethiopians have significant Arabian ancestry, but little Iranian or Bantu ancestry.

Beginnings And What We Don't Know In Physics

This post lays out the fact that we know almost all of the fundamental laws of physics, and describes what I see as the most plausible resolutions to the ones for which we don't have consensus answers.

We Understand The Particle Physics Of Everything But The First Fraction Of A Second After The Big Bang

In the standard chronology of the universe in cosmology, there is a state change from quark-gluon plasma to confined hadrons (mostly protons and neutrons) at one second after the Big Bang. 

This is only a rough approximation, however. The physics of the Standard Model up to this temperature (about 5.5 trillion degrees Kelvin) have been experimentally confirmed at the Large Hadron Collider. More exactly, this temperature, where the quark-gluon plasma state change is expected ends at 10^-12 seconds after the Big Bang, in the standard chronology of the universe, dramatically shrinking the time period in the universe where we don't fully understand the relevant particle physics from the first second, to the first trillionth of a second. The trillionth of a second in the history of the universe where the Standard Model has not been experimentally confirmed is one part per 10^30 of the time that the universe has existed. 

The Standard Model is mathematically consistent and sound for at least another twenty-two orders of magnitude beyond that point (i.e. up to the GUT scale), to one part per 10^52 of the time that the universe has existed, but hasn't been experimentally tested in the higher energy parts of that domain. 

The hypothetical Planck epoch, which is a point where the Standard Model equations might break down, is about three orders of magnitude smaller in the time after the Big Bang. The Planck time, a dimensional reasoning based theoretical possible minimum unit of time, is about 10^-43 seconds and would be characterized by energy scales of 10^19 GeV or greater. Classical general relativity predicts a gravitational singularity before this point, although a quantum gravity theory might not have a singularity.

This chronology assumes that Big Bang Nucleosynthesis with the newly formed protons and neutrons begins about ten seconds after the Big Bang and lasts for about sixteen and a half minutes. The particle and nuclear physics of Big Bang Nucleosynthesis are scientifically well understood, and the predictions of the BBN model are confirmed with observations, subject to some modest discrepancies in lithium levels that recent astronomy observations have tended to confirm by finding missing lithium levels and better modeling lithium production and destruction during the 13.7 billion years between the end of BBN and the present in nuclear reactions in stars.

So, any "new physics" that arise at energies above those that the Large Hadron Collider could reach are restricted to some fraction of the first second of the Universe. We fully understand the laws of physics (except dark matter and dark energy and possibly quantum gravity) that apply in the circumstances found in the universe at all time after that.

There are three main possible kinds of "new physics" motivated by astrophysics that scientists are looking for, and one kind of unobserved Standard Model physics that hasn't been observed because energies are too low, that could be restricted to the high energies found only in the first second after the Big Bang. They are, respectively: Cosmological inflation, baryogenesis, leptogenesis, and baryon number and lepton number non-conserving (but B-L preserving) sphaleron interactions.

Sphaleron interactions, while theoretically interesting, aren't enough to explain baryogenesis or leptogenesis, or any other phenomena in the world later than a fraction of a second after the Big Bang, so while undiscovered and theoretically interesting, are basically a side curiosity. These also require temperatures about 100 times the hottest temperature reached at the LHC, so the time frame in which they could have occurred is significantly less than a trillionth of a second.

The cosmology narrative that I find most plausible, mirror cosmology, simultaneously eliminates the need for cosmic inflation, explains the baryon asymmetry of the universe without post-Big Bang new physics, and answers the question "how could something come out of nothing" at least partially by causing the Big Bang to no longer violate mass-energy conservation. 

Deur's approach to gravity meanwhile, eliminates the need for either dark matter or dark energy, and solves all or many of the problems with the LambdaCDM Standard Model of Cosmology, and has been explored preliminarily not just at the scale of galaxies and galaxy clusters, but also in cosmology applications. He also eliminates the mass-energy conservation exception (the only one in physics other than the Big Bang itself) associated with dark energy by a means that I've not seen utilized by any other theory in astrophysics.

Baryogenesis and Leptogenesis

The baryon asymmetry of the universe (i.e. the vast excess of protons and neutrons over anti-protons and anti-neutrons) requires one of two things: 

(1) the large positive net baryon number of the Universe (i.e. the excess of protons and neutrons over anti-protons and anti-neutrons) was present essentially at the outset of the Big Bang, or 

(2) the Big Bang started with matter and antimatter in perfect balance and sometime in the first second after the Big Bang, a baryon number non-conserving process that violates CP conservation much more strongly than any process in the Standard Model exists at energies higher than those in the Standard Model generating the asymmetry seen today.

Mirror cosmology, in which there is an anti-matter universe before the Big Bang in time, and our matter universe after it, explains baryogenesis and leptogenesis without new physics and basically allows the Universe as a whole to have equal amounts of matter and antimatter, while not requiring a new charge parity (CP) violating process not found in the Standard Model at high energies (except for a time bias between matter and antimatter in pair production of quarks and leptons at the time of the Big Bang). 

As quarks and antiquarks are photoproduced at the Big Bang, the quarks disproportionately end up on our side of the Big Bang, and the antiquarks disproportionately end up before the Big Bang in time. 

As charged leptons and charged antileptons are photo-produced at the Big Bang, the charged leptons disproportionately end up on our side of the Big Bang and the anti-leptons disproportionately end up before the Big Bang in time. 

Neutrinos, by the way, aren't photoproduced because they don't have an electromagnetic charge. So, the neutrinos in our post-Big Bang observable universe, would all be created post-Big Bang in lepton number conserving interactions. And, while beta decay can create an electron and an anti-neutrino, given what we know about the frequency of beta decay and the proportion of protons and neutrons in the universe, the net lepton number of the universe should be at least similar to the number of charged leptons in the universe (which is almost identical to the number of protons in the universe), while the number of anti-neutrinos should only slightly and imperceptibly exceed the number of neutrinos in the our observable universe. 

Cosmological Inflation

Cosmological inflation is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10^−36 seconds after the conjectured Big Bang singularity to some time between 10^−33 and 10^−32 seconds after the singularity. Following the inflationary period, the universe continued to expand, but at a slower rate.

Inflation presumes an expansion of space at faster than the speed of light in this time period. At the speed of light, in 10^−32 seconds, light moves 10^−24 meters (by comparison a proton is about 10^−15 meters across). But, in one typical inflation theory, space expands from a 10^-50 meter radius at 10^-35 seconds after the Big Bang to about a 1 meter radius at 10^-34 seconds.

These new inflation physics purportedly appear so early on in this scenario, that the entire universe would fit in my bathroom with room to spare. The energy scale at which this is supposed to happen is the GUT scale, i.e. about 10^15 GeV to 10^16 GeV.

Put another way, cosmological inflation is a one time fix that ends when the universe has a one meter radius in the first 10^-34 seconds after the Big Bang, or so, so it is functionally just a set of hypothesized initial conditions of the universe from that moment slightly after the Big Bang.

The Wikipedia article on Cosmic Inflation explains:

It explains the origin of the large-scale structure of the cosmos. Quantum fluctuations in the microscopic inflationary region, magnified to cosmic size, become the seeds for the growth of structure in the Universe (see galaxy formation and evolution and structure formation). Many physicists also believe that inflation explains why the universe appears to be the same in all directions (isotropic), why the cosmic microwave background radiation is distributed evenly, why the universe is flat, and why no magnetic monopoles have been observed.

The detailed particle physics mechanism responsible for inflation is unknown. The basic inflationary paradigm is accepted by most physicists, as a number of inflation model predictions have been confirmed by observation; however, a substantial minority of scientists dissent from this position. The hypothetical field thought to be responsible for inflation is called the inflaton.

There are literally hundreds of proposed inflation theories (a 300 page summary of the various inflation theories can be found here) and astronomy observations have time and again narrowed the parameter space of potential inflation theories to rule out a great many of them. See, e.g., prior posts from this blog on March 21, 2013, March 18, 2014, July 24, 2017, and October 4, 2021. In the first of those posts, I noted that:

Planck [cosmic microwave background observations] strongly disfavors power law inflation, the simplest hybrid inflationary models, simple monomial models with n > 2, single fast roll inflation scenarios, multiple stage inflation scenarios, inflation scenarios with flat or concave potentials, dynamical dark energy, time variations of the fine structure constant are all strongly disfavored. Any theory that would create non-Gaussian statistics of the CMB anisotropies, non-flat universes, tensor modes, or statistically discernible deviations from isotropy at L >50 are ruled out.

The summary chart from the 2021 paper is as follows:

Only the blue part of the parameter space remains open, so "natural inflation" is ruled out.

Many people (including many serious astrophysicists and me) are skeptical that cosmic inflation is really necessary. In an October 31, 2016 post, I noted that even one of inflation theory's original creators doubts that it really exists. 

Paul Steinhardt gave a colloquium at Fermilab last month with the title Simply Wrong vs. Simple. In it he explained “why the big bang inflationary picture fails as a scientific theory” (it doesn’t work as promised, is not self-consistent and not falsifiable).

Deur's gravitational work is agnostic on the subject.  

An abstract of a paper on the topic of mirror cosmology also explains the basic astronomy motivation for cosmic inflation, and why the mirror cosmology model dispenses with the need for it.

Observations indicate that the early Universe was strikingly simple: a fraction of a second after the Big Bang, the Universe was radiation-dominated, almost perfectly homogeneous, isotropic, and spatially flat; with tiny (around 10^−5) deviations from perfect symmetry also taking a highly economical form: random, statistically gaussian, nearly scale-invariant, adiabatic, growing mode density perturbations.

Although we cannot see all the way back to the bang, we have this essential observational hint: the further back we look (all the way back to a fraction of a second), the simpler and more regular the Universe gets. This is the central clue in early Universe cosmology: the question is what it is trying to tell us.

In the standard (inflationary) theory of the early Universe one regards this observed trend as illusory: one imagines that, if one could look back even further, one would find a messy, disordered state, requiring a period of inflation to transform it into the cosmos we observe.

An alternative approach is to take the fundamental clue at face value and imagine that, as we follow it back to the bang, the Universe really does approach the ultra-simple radiation-dominated state described above (as all observations so far seem to indicate).

Then, although we have a singularity in our past, it is extremely special. Denoting the conformal time by τ , the scale factor a(τ) is ∝ τ at small τ so the metric g^(µν) ∼ a(τ)^(2ηµν) has an analytic, conformal zero through which it may be extended to a “mirror-reflected” universe at negative τ.

[W]e point out that, by taking seriously the symmetries and complex analytic properties of this extended two-sheeted spacetime, we are led to elegant and testable new explanations for many of the observed features of our Universe including: . . . (ii) the absence of primordial gravitational waves, vorticity, or decaying mode density perturbations; (iii) the thermodynamic arrow of time (i.e. the fact that entropy increases away from the bang); and (iv) the homogeneity, isotropy and flatness of the Universe, among others.

The Dark Sector

Deur's work on gravity, purports to explain the phenomena attributed to dark matter and dark energy with non-perturbative weak field gravitational effects. Other gravity based approaches (e.g. here) likewise seek to explain dark matter and dark energy without new particles or substances, in various ways, one of the most notable of which adds conformal symmetry to the constraints of general relativity. 

In my opinion, the balance of the evidence strongly favors either some gravitational explanation for dark matter or an ultralight bosonic dark matter particle with a mass-energy on the same order of magnitude as a graviton that looks a lot like a fifth force. 

One of the strongest pieces of evidence that dark matter, if it exists, must be very light is Alfred Amruth, "Einstein rings modulated by wavelike dark matter from anomalies in gravitationally lensed images" Nature Astronomy (April 20, 2023) https://doi.org/10.1038/s41550-023-01943-9 (Open access copy available at arxiv).

And, the gravitational approach is better motivated in y humble opinion, and has more rigorously been confronted with the evidence.

Deur's approach to gravity is more intuitive in a graviton based quantum gravity context, but he claims that it works in unmodified classical general relativity (without a cosmological constant) as well if non-perturbative effects are considered.

If Deur is correct, there is about 95% less mass-energy in the universe than expected in the LambdaCDM Standard Model of Cosmology, and there is no observational motivation for stable particles not explained by the Standard Model of Particle Physics (other than gravitons) to exist.

Mass-Energy Conservation

By eliminating the need for dark energy, Deur also removes the one exception to conservation of mass-energy in general relativity (and physics generally) that dark energy creates, except at the moment of the Big Bang when you have a "something created out of nothing" issue. This is solved at the moment of the Big Bang in mirror cosmology.

Quantum Gravity

Another benefit of removing the cosmological constant from general relativity is that it makes it easier to formulate a quantum gravity theory if you don't need to include the Lambda (i.e. cosmological constant) term from Einstein's field equations (which incidentally is a gravitational explanation for dark energy).

This isn't the biggest barrier to a quantum gravity theory, however. The biggest barrier is that general relativity isn't renormalizable, which is a property that any usable and non-pathological theory of quantum gravity should have, at least not perturbative the way that the three Standard Model forces are.

But, it looks like the same approach the Deur took to explain dark matter and dark energy phenomena, non-perturbative effects of general relativity, also make general relativity non-perturbatively renormalizable. This suggest a roadmap for finally crossing the seemingly insurmountable barrier of mathematically formulating a quantum gravity theory.

There are, however, quite strict observational constraints on quantum gravity effects.

If quantum gravity does exist, the gravitational coupling constant has a beta function that explains how it runs with energy scale, which could also provide useful insight and ought to be possible to devise from first principles. One effort to do so is mentioned here.

The existence of quantum gravity would also slightly tweak the beta functions of the other Standard Model experimentally measured physical constants, which might have interesting implications at very high energies.

Neutrinos

Science still need to pin down some of the physical constants associated with neutrinos (which is just a matter of brute force effort and isn't theoretically problematic) and the nature of neutrino mass (Majorana or Dirac). I strongly suspect that neutrinos have Dirac mass and have some ideas about where it comes from (basically, through W boson and/or Z boson mediated interactions and self-interactions).

Explaining the Standard Model Constants

The only other thing we don't know in physics that would be nice to know (although it isn't strictly necessary to explain the observed universe) is the way that the physical constants for the fifteen experimentally measured masses of the Standard Model (which are only fourteen degrees of freedom because the W and Z boson masses are functionally related to each other in the electroweak theory of the Standard Model), the eight parameters of the CKM matrix and the PMNS matrix, and the three Standard Model coupling constants (as well as Newton's constant, Planck's constant, and the speed of light). The electromagnetic and weak force coupling constants are also functionally related to each other and to the W and Z boson masses. 

There is good reason to believe that a "within the Standard Model" theories could explain a great many of these physical constants a derived values rather than just experimentally measured physical constants. 

The masses of the Standard Model fundamental particles, which have origins in the electroweak sector of the model, seem particularly susceptible to being explained this way, that I've explored in prior posts at this blog. Basically, I think that Koide's rule and extensions of this point to the Yukawa couplings to the Higgs field having their roots in dynamic balancing of these values through W boson interactions. The LP & C relation suggests a connection between the Higgs vacuum expectation value (which is a function of the W boson mass and the weak force coupling constant) is the source of the overall mass scale of the fundamental particles of the Standard Model.

It might also be possible to reduce the number of non-derived CKM matrix parameters from four to two with a little more theoretical work, and maybe someday, similar progress could be made with the four PMNS matrix parameters. 

These efforts wouldn't bring the number of experimentally measured fundamental physical constants in the Standard Model to zero or even to one, but it might be possible to get them down, perhaps, from twenty-five to eight (plus the speed of light, Planck's constant, and Newton's constant).

Fourth Generation (Or Greater) Standard Model Fermions

It is very unlikely that there are fourth generation fundamental fermions. Instead, there are exactly three generations of Standard Model fermions. 

For theoretical reasons, there has to be a full set of an up-type quark, down-type quark, charged lepton, and neutrino in each generation. 

Direct searches and cosmology observations rule out these possibilities up to high masses relative to the third generation. This is particularly in the case of a four generation active Standard Model neutrino; which has been ruled out to, at least, 45,000,000,000 eV (the heaviest of the three Standard Model neutrino masses is not more than 2 eV by direct measurements and neutrino oscillation data, and is less than 0.1 eV based upon cosmology bounds). Fourth generation down type quarks are ruled out up to 3,000 GeV by direct searches (the b quark mass is about 4.2 GeV). Fourth generation up  type quarks are ruled out up to 1,500 GeV by direct searches (the t quark mass is about 173 GeV). Fourth generation charged leptons are ruled out up to 100.8 GeV by direct searches (the tau lepton mass is about 1.78 GeV).

Also, from a theoretical perspective, a fourth generation or higher Standard Model fermion more massive that then top quark is ruled out because its expected mean lifetime would be shorter than the mean lifetime of the W boson that effects its decay. The mean lifetimes of the W and Z bosons, which are the most short-lived particles ever observed, are each about 3*10^-25 seconds. The mean lifetime of the top quark is about 5*10^-25 seconds, which is the shortest of the Standard Model fermions and is so short that top quarks decay before they can hadronize.

Furthermore, the existence of fourth generation fundamental Standard Model fermions would cause the decays of the Standard Model Higgs boson to differ greatly from what is observed.

The Strong CP Problem

I also have my own heuristic answer to the strong CP problem, which is that since gluons that mediate the strong force are massless and thus don't experience time in their own reference frame, that neither gluons, nor any other massless particles, can experience CP violation which is equivalent to time symmetry violation.

This makes a hypothetical axion particle to suppress CP violation in strong force interactions unnecessary.

Quote Of The Day

This paper is both novel and correct, but the novel part is not correct and the correct part is not novel.

From a peer review of an academic journal article attributed to physicist Wolfgang Pauli.

Papuan Demographic History From Modern Genomes

A new pre-print at bioRxiv disputes the status of Papuans (presumably together with aboriginal Australians) as an outgroup to both European and Asian populations. Instead, it positions them as a sister population of other Asian populations.

The demographic history of the Papua New Guinean population is a subject of significant interest due to its early settlement in New Guinea, at least 50 thousand years ago, and its relative isolation compared to other out of Africa populations. This isolation, combined with substantial Denisovan ancestry, contributes to the unique genetic makeup of the Papua New Guinean population. Previous research suggested the possibility of admixture with an early diverged modern human population, but the extent of this contribution remains debated. 

This study re-examines the demographic history of the Papua New Guinean population using newly published samples and advanced analytical methods. Our findings demonstrate that the observed shifts in relative cross coalescent rate curves are unlikely to result from technical artefacts or contributions from an earlier out of Africa population. Instead, they are likely due to a significant bottleneck and slower population growth rate within the Papua New Guinean population. Our analysis positions the Papua New Guinean population as a sister group to other Asian populations, challenging the notion of Papua New Guinean as an outgroup to both European and Asian populations. 

This study provides new insights into the complex demographic history of the Papua New Guinean population and underscores the importance of considering population-specific demographic events in interpreting relative cross coalescent rate curves.

Mayukh Mondal, et al., "Resolving out of Africa event for Papua New Guinean population using neural network" bioRxiv (September 23, 2024) https://doi.org/10.1101/2024.09.19.613861

The introduction to the paper explains that:

The Papua New Guinean (PNG) population is among the most fascinating in the world, owing to its unique demographic history. Following the Out Of Africa (OOA) event, modern humans populated New Guinea at a remarkably early date-at least 50 thousand years ago. Since then, the population has remained relatively isolated compared to other OOA populations (such as European and Asian populations) and has gone through a strong bottleneck. The substantial Denisovan ancestry within the PNG population and the strong correlation between Denisovan and Papuan ancestries, contribute to the genetic distinctiveness of the PNG population. 

Researchers have suggested that the genomes of PNG populations contain evidence of admixture with a modern human population that might have diverged from African populations- around 120 thousand years ago- much earlier than the proclaimed primary divergence between African and OOA populations. However, the extent to which this early diverged population contributed to the genome of PNG populations remains a subject of ongoing debate. Interestingly, this early migration hypothesis is more widely accepted by archeologists. 

Pagani et al supports this hypothesis, notably through Relative Cross-Coalescent Rate (RCCR) analysis. This RCCR analysis suggests that the PNG population diverged from African populations significantly earlier than other OOA populations. They argued that this earlier divergence indicated by the RCCR curve might reflect a contribution from an earlier OOA population specific to PNG. While this shift in the RCCR curve is well-documented, some researchers attribute it to technical artefacts such as low sample sizes and phasing errors rather than genuine demographic events. 

The origins of the primary lineage of the PNG population have also been contested. Some researchers propose that the PNG population is closely related to the Asia-Pacific populations and serves as a sister group to other Asian populations. Conversely, other researchers argue that the PNG population is an outgroup to both European and Asian populations. 

Recent advancements in analytical methods may provide new insights into these debates. For example, Approximate Bayesian Computation with Deep learning and sequential Monte Carlo (ABC-DLS) allows for the use of any summary statistics derived from simulations to train neural networks, which can then predict the most likely demographic models and parameters based on empirical data. Additionally, the Relate software enhances RCCR analysis by employing a modified version of the hidden Markov model, initially used in the Multiple Sequentially Markovian Coalescent (MSMC) method, allowing for the analysis of thousands of individuals with greater robustness. 

In this paper, we re-examine the demographic history of the PNG population using newly published samples combined with data from the 1000 Genome Project and cutting edge methods. This approach has enabled us to address these longstanding questions with greater precision. We first generate new empirical RCCR curves and demonstrate that the previously observed shift is unlikely to be the result of low sample size or phasing errors. Through simulations, we further show that the PNG population is indeed a sister group to other Asian populations and this shift is probably not due to contributions from an earlier OOA population. Instead, it is likely a consequence of a significant bottleneck and slower population growth in the PNG population.

The paper then defines the demographic models that the paper analyzed at a broad brush level:

To explore the demographic processes causing the observed RCCR shift, we tested five plausible demographic scenarios labelled A, O, M, AX and OX. In Model A, the PNG and East Asian populations are sister groups. Model O positions the PNG population as an outgroup to both European and East Asian populations. Model M combines elements of both A and O, suggesting that the PNG population arose from admixture between a sister group of the Asian population and an outgroup of European and Asian populations. Model AX postulates that the PNG population is a sister group to the Asian population but received input from an earlier OOA population. Finally, in Model OX, the PNG population receives a contribution from an earlier OOA population, while remaining ancestry came from an out group to the European and East Asian populations. . . .  

The best-fitting parameters for Model A largely correspond with the previously established OOA model, with some deviations specific to the inclusion of the PNG population. 

Our model suggests that all OOA populations, including PNG, diverged from African populations (represented by Yoruba) around 62.4 (62- 62.8) thousand years ago, experiencing a significant bottleneck. Approximately 52 (51.6- 52.8) thousand years ago, Neanderthals contributed around 3.7% (3.59- 3.85%) of the genome to these OOA populations. Shortly thereafter, Europeans and East Asians diverged from the PNG populations around 51.2 (50.8- 51.6) and 46.2 (45.9- 46.5) thousand years ago, respectively. The PNG population then mixed with Denisovans around 31.2 (31.1- 31.5) thousand years ago, contributing approximately 3.16% (3.05- 3.21%) to the genome of PNG. 

Our analysis also shows that the PNG population experienced a more severe bottleneck (674 [663- 689] of effective population size) than other OOA populations (i.e. Europeans 3512 [3423- 3589] and East Asians 1771 [1730- 1799] of effective population size), with growth rates significantly lower than those of other OOA populations, consistent with previously published data. 

While our parameter inference is generally robust within the individual model, substantial changes occur when the underlying model is altered. Given that determining the precise demographic model for human populations is an ongoing effort, parameter estimates should be considered supplementary to the model rather than independent results. 

The concluding discussion of the results notes that:

We successfully replicated the shift observed by Pagani et al., confirming its presence in both physically mapped and statistically phased sequences, which involved over 100 PNG samples. This consistency suggests that the shift is reproducible, though its underlying cause may differ from the original interpretation of Pagani et al.. 

Our analysis using ABC-DLS supports a simpler demographic model for PNG populations, proposing them as a sister group to Asians with no substantial detectable contribution from an earlier OOA population. Interestingly, our simulated models reveal that a stronger bottleneck with a lower growth rate could produce a similar shift in RCCR analysis and potentially be misinterpreted as a signal of an earlier population separation. While RCCR is a valuable proxy for estimating the separation time between populations, it is not without biases. The shift could result from various factors, including earlier divergence times, admixture with earlier diverged populations, or even a bottleneck in one of the populations, as demonstrated in our study. Interestingly this demographic history of stronger bottleneck with slower growth rate was also experienced by the Andamanese population, which explains the shift found in the Andamanese population as well. Thus, using RCCR analysis to rebuild the tree of divergence might need to be revised.

The observed shift in the RCCR curve suggests that a recent bottleneck can impact estimates of effective population size in the distant past. Notably, in our simulations, the Papua New Guinean bottleneck occurred much later (around 46.2 thousand years ago) than the observed shift (peaking around 100 thousand years ago) with a population (Yoruba) that separated a long time ago. This finding implies that the estimation of effective population size and cross-coalescent rates may not be entirely independent, potentially affecting RCCR analysis in its current form. Further analysis suggests that the estimation of coalescent rate was affected earlier than true changes of effective population size, which shifts the RCCR curve as RCCR is a ratio of coalescent rates. Additionally, this shift was absent in simulations involving populations that separated 300 thousand years ago, akin to the San population, indicating that the bottleneck effect diminishes over longer separation times.

Our results also reveal that when the contribution from an earlier OOA population is between 1-5%, our neural analysis misclassifies the Model AX to be Model A at a higher rate. We found that when the contribution from an earlier OOA population is set between 1-5%, our ABC-DLS analysis tends to misclassify the Model AX as Model A at a higher rate. A similar issue arises with Model M, where a low contribution (less than 5%) from an outgroup Eurasian population can still be misclassified as Model A. Thus our analysis does not work for less than 5% contribution from these unknown ghost populations, though Model OX does not show a similar phenomenon with Model A misclassification. While we cannot completely rule out the possibility of a small contribution from these populations, our analysis suggests that such models are not necessary to explain the RCCR shift as previously proposed.

Interestingly, our results position PNG as a sister group to Asian populations rather than an outgroup of European and Asian. The primary difference between those models and ours lies in the migration rates between populations. Previous models that incorporated significant migration rates between populations were found to have confounded results, leading us to avoid including migration rates in our models. Without migration, our Model O closely resembles the previous models of PNG. Given that those models used substantial migration rates, they are not directly comparable to our models without migration rate. Indeed with high migration rates, our approach failed to distinguish between Model A and O with high certainty. Still our work suggests that the main lineage of PNG is coming from a sister group of Asia, which was not confounded by a convoluted migration rate patterns between populations.

Our parameter estimation suggests that the PNG population separated from other populations around 46.2 (45.9 - 46.5) thousand years ago, a timeline that aligns with archaeological estimates of when the ancestors of PNG reached the ancient continent of Sahul, the landmass that once connected New Guinea and Australia. 

Additionally, our Relate analysis indicates that the separation time between PNG and European populations was the longest observed among OOA populations. However, as our model suggests, this is likely a bias caused by the bottleneck of PNG. This bottleneck may lead to an overestimation of the separation time, particularly in RCCR analysis. In reality, it is more likely that PNG and East Asian populations separated later than the divergence between PNG and European populations. 

In conclusion, our study provides compelling evidence that the unique demographic events—specifically, a significant bottleneck and slower population growth—within the PNG population are key factors influencing the observed shifts in RCCR curves. These findings not only refine our understanding of PNG's demographic history but also emphasise the necessity of accounting for population-specific demographic events when interpreting RCCR curves. 

Semi-Recessive Genes

Some genes classified as recessive genes that have their main phenotypical effects only when both copies of it are present, are actually only "semi-recessive" and have much milder versions of the same phenotypic effects in "carriers" with only one copy of the gene.

A new pre-print at bioRxiv demonstrates this by looking at 1929 genes considered recessive in the British UK Biobank database which includes 378,751 unrelated European individuals, singling out carriers of recessive genes associated with intellectual disabilities, who exhibit below average intellectual abilities themselves, as an example.

The abstract explains that:

The genetic landscape of human Mendelian diseases is shaped by mutation and selection. Selection is mediated by phenotypic effects which interfere with health and reproductive success. Although selection on heterozygotes is well-established in autosomal dominant disorders, convincing evidence for selection in carriers of pathogenic variants associated with recessive conditions is limited, with only a few specific cases documented.

We studied heterozygous pathogenic variants in 1,929 genes, which cause recessive diseases when bi-allelic, in a cohort of 378,751 unrelated European individuals from the UK Biobank. We assessed the impact of these pathogenic variants on reproductive success. We find evidence for fitness effects in heterozygous carriers for recessive genes, especially for variants in constrained genes across a broad range of diseases. Our data suggest reproductive effects at the population level, and hence natural selection, for autosomal recessive disease variants. We further show that variants in genes that underlie intellectual disability are associated with reduced cognition measures in carriers. In concordance with this, we observe an altered genetic landscape, characterized by a threefold reduction in the calculated frequency of biallelic intellectual disability in the population relative to other recessive disorders. The existence of phenotypic and selective effects of pathogenic variants in constrained recessive genes is consistent with a gradient of heterozygote effects, rather than a strict dominant-recessive dichotomy.

Hila Fridman, et al., "Reproductive and cognitive effects in carriers of recessive pathogenic variants" bioRxiv (October 1, 2024). https://doi.org/10.1101/2024.09.30.615774

Dark Matter Is Still Probably The Wrong Answer

Stacy McGaugh has a reaction blog post to the Scientific American article "What if We Never Find Dark Matter?" by Slatyer & Tait.

It nicely sums up the sociological conundrum in astrophysics that has led the discipline to throw a lot of weight and support behind a deeply flawed dark matter particle hypothesis with a particle that hasn't been detected and no hypothetical particle that can fit the astronomy observations and no theory that has made many significant ex ante predictions, rather than MOND and modified gravity that is a much better fit to the astronomy observations and has made many significant ex ante predictions.

He is spot on. Some good quotes:

In the 1980s, cold dark matter was motivated by both astronomical observations and physical theory. Absent the radical thought of modifying gravity, we had a clear need for unseen mass. Some of that unseen mass could simply have been undetected normal matter, but most of it needed to be some form of non-baryonic dark matter that exceeded the baryon density allowed by Big Bang Nucleosynthesis and did not interact directly with photons. That meant entirely new physics from beyond the Standard Model of particle physics: no particle in the known stable of particles suffices. This new physics was seen as a good thing, because particle physicists already had the feeling that there should be something more than the Standard Model. There was a desire for Grand Unified Theories (GUTs) and supersymmetry (SUSY). SUSY naturally provides a home for particles that could be the dark matter, in particular the Weakly Interacting Massive Particles (WIMPs) that are the prime target for the vast majority of experiments that are working to achieve the exceptionally difficult task of detecting them. So there was a confluence of reasons from very different perspectives to make the search for WIMPs very well motivated.

That was then. Fast forward a few decades, and the search for WIMPs has failed. Repeatedly. Continuing to pursue it is an example of the sunk cost fallacy. We keep doing it because we’ve already done so much of it that surely we should keep going. So I feel the need to comment on this seemingly innocuous remark:

although many versions of supersymmetry predict WIMP dark matter, the converse isn’t true; WIMPs are viable dark matter candidates even in a universe without supersymmetry.

Strictly speaking, this is correct. It is also weak sauce. The neutrino is an example of a weakly interacting particle that has some mass. We know neutrinos exist, and they reside in the Standard Model – no need for supersymmetry. We also know that they cannot be the dark matter, so it would be disingenuous to conflate the two. Beyond that, it is possible to imagine a practically infinite variety of particles that are weakly interacting by not part of supersymmetry. That’s just throwing mud at the wall. SUSY WIMPs were extraordinarily well motivated, with the WIMP miracle being the beautiful argument that launched a thousand experiments. But lacking SUSY – which seems practically dead at this juncture – WIMPS as originally motivated are dead along with it. The motivation for more generic WIMPs is lacking, so the above statement is nothing more than an assertion that runs interference for the fact that we no longer have good reason to expect WIMPs at all. . . . 

I can save everyone a lot of time, effort, and expense. It ain’t WIMPs and it ain’t axions. Nor is the dark matter any of the plethora of other ideas illustrated in the eye-watering depiction of the landscape of particle possibilities in the article. These simply add mass while providing no explanation of the observed MOND phenomenology. This phenomenology is fundamental to the problem, so any approach that ignores it is doomed to failure. I’m happy to consider explanations based on dark matter, but these need to have a direct connection to baryons baked-in to be viable. None of the ideas they discuss meet this minimum criterion.

Of course it could be that MOND – either as modified gravity or modified inertia, an important possibility that usually gets overlooked – is essentially correct and that’s why it keeps having predictions come true. That’s what motivates considering it now: repeated and sustained predictive success, particularly for phenomena that dark matter does not provide a satisfactory explanation for. . . . 

The equation coupling dark to luminous matter I wrote down in all generality in McGaugh (2004) and again in McGaugh et al. (2016). The latter paper is published in Physical Review Letters, arguably the most prominent physics journal, and is in the top percentile of citation rates, so it isn’t some minuscule detail buried in an obscure astronomical journal that might have eluded the attention of particle physicists.

Bonus quote from the comments:

It’s exactly the same crap as with string theory, and supersymmetry, and inflation, and dark sectors, and many other research bubbles in the foundations of physics. It is mathematical fiction; it’s nothing to do with reality any more.

- Sabine Hossenfelder (YouTube link).

A New Published Koide Triple Paper

Arivero at the Physics Forums (who comments here from time to time) has gotten his article on Koide Triples published:

I had put in a preprint some calculations of Koide masses using the original composite idea and they have happened to be published as Eur. Phys. J. C 84, 1058 (2024). https://doi.org/10.1140/epjc/s10052-024-13368-3, so as a collateral effect we now have another published paper that mentions:

• the waterfall, in a footnote.
• the tuples (0ds), (scb) and (cbt).
• the relation sum(scb) = 3 sum (leptons).

It is nice to see this promising line of inquiry advanced. The preprint linked and its abstract are as follows:

We propose an interpretation for the adjoint representation of the SO(32) group to classify the scalars of a generic Supersymmetric Standard Model having just three generations of particles, via a flavour group SU(5). 

We show that this same interpretation arises from a simple postulate of self-consistence of composites for these scalars. The model looks only for colour and electric charge, and it pays the cost of an additional chiral +4/3 quark per generation.

Alejandro Rivero, "An interpretation of scalars in SO(32)" arXiv:2407.05397 (July 7, 2024). The published version is open access and was published on October 15, 2024.

Bonus: The article contains a cute "Turtles All The Way Down" illustration, which we here on Turtle Island, appreciate.