Kaluza's law
Kaluza's law proposes a phonological constraint on the metre of the Old English poem "Beowulf". It takes its name from Max Kaluza, who made an influential observation on the metrical characteristics of unstressed syllables in "Beowulf". His insight was developed further in particular by Alan Bliss and R. D. Fulk. The name 'Kaluza's law' itself appears to have been bestowed by Fulk. The significance of Kaluza's observations for the dating of "Beowulf" has been extensively debated. The law. Like other Old Germanic languages alliterative verse, the Old English poetic metre of "Beowulf" exhibits the  phenomenon of resolution, whereby, under certain conditions, two syllables count as one for metrical purposes. These conditions are: Kaluza's observations suggested that "Beowulf" exhibits a further constraint on condition 5, concerning the unstressed syllable in the pair of syllables that are to resolve. When the two potentially resolving syllables immediately follow a stressed syllable, resolution does not happen if: Thus in lines categorised in Sievers' theory of Anglo-Saxon meter as A2a, such as "Beowulf" line 222a (") or 1171a ("), the second and third syllables (in these examples " and " respectively) resolve, and in these cases they consistently end in an  etymologically short vowel, with no consonant. (These are sometimes known as 'Kaluza Type I verses' and there are sixty-two examples in the poem.) Yet in lines of type D2 and D*2, such as "Beowulf" line 2042a (") or 2912b (") the potentially resolving syllables (in these examples " and ") follow a stressed syllable (in these examples " and ") and might in theory resolve. If they did, however, the line would contain only three syllables, too few to meet the four-syllable minimum requirement of Old English alliterative metre. In such verses in "Beowulf", the unstressed syllable consistently includes a consonant and/or has an  etymologically long vowel. (These are sometimes known as 'Kaluza Type II verses' and there are forty-four examples in the poem.) R. D. Fulk developed Kaluza's observations to argue that they show that at the time when "Beowulf" was composed, poetic varieties of Old English still distinguished between long and short vowels in unstressed syllables. There is no precise evidence for when these distinctions were lost, but there is a range of evidence for other kinds of unstressed vowel reduction in the history of Old English. This evidence suggests that vowel-length distinctions in unstressed vowels could not have  persisted beyond in Mercian Old English or in Northumbrian Old English. This implies a relatively early date for "Beowulf". No other Old English poem coheres to Kaluza's law to any significant degree. Alternative explanations. Most linguists who have considered Kaluza's law hold that the patterns in "Beowulf" reflect a phonological constraint in early Old English poetic metre. However, several scholars have argued that the appearance of Kaluza's law patterns in "Beowulf" specifically may not reflect the continued distinction between long and short vowels in unstressed syllables at the time of "Beowulf"<nowiki>'</nowiki>s composition, but a residual  conformity to older patterns arising from any of a range of postulated factors, including: Leonard Neidorf and Rafael J. Pascual contend that these alternative explanations are weaker than the phonological explanation preferred by Kaluza and Fulk.