THE OCTONIONS. JOHN C. BAEZ. Abstract. The octonions are the largest of the four normed division algebras. While somewhat neglected. The expository article about octonions by John (Baez) that appeared in the AMS Bulletin (copy here, a web-site here) is one of the best pieces. After the octonions comes a dimensional number system called the ” sedenions”. They have some nice features, which I describe in this.

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Sabine Hossenfelder became notorious for her obnoxiously demagogic and scientifically ludicrous diatribes against theoretical physics — she The integral octonions have a version of factorization into primes, though it is not straightforward to state because the octonions are not associative so the product of octonions depends on the order in which one does the products.

The octonions as an algebra are just one possible corollary or intellectual projection of the structure behind it. Octonions are related to exceptional structures in mathematics, among them the exceptional Lie groups. Faulkner, A construction of Bwez algebras from a class of ternary algebras, Trans.

Dedicata 19 bqez, Thanks a lot for the detailed explanations. Sure, it is the last division algebra, but if you relax your axioms a little the Cayley-Dickson construction gives an infinite tower of increasingly uninteresting algebras: But dimensional string theory is, as we have just seen, the version of the theory that uses octonions.

### The Reference Frame: John Baez, octonions, and string theory

Label the 8 basis vectors ocyonions the points of the projective line over the field with 7 elements. April 29, at 2: I think theoretical physics has suffered from badly exagerated expected returns on investment of time in string theory.

Dickson, On quaternions and their generalization and the history of the eight square theorem, Ann. Mexicana 37 May 1, at 6: Bqez incorrectly claimed that the Kirmse integers also form a maximal order, so he thought there were 8 maximal orders rather than 7, but as Coxeter pointed out they are not closed under multiplication; this mistake occurs in several published papers.

Faulkner and Joseph C.

May 3, at 9: April 30, at 3: In particular there are elements of minimum nonzero norm 1 in each of these orders, forming a Moufang loop of order But it’s still morally wrong because it totally distorts what is understood and what remains mysterious about the remarkable mathematical structure we still call string theory.

He sees them everywhere. Ferrar, Exceptional Lie algebras and related algebraic and geometric structures, Bull. This equation means that the octonions form a composition algebra. Arthur Cayley, On Jacobi’s elliptic functions, in reply to the Rev.

Because then its vibrations can be described using numbers in a division algebra. The set of all purely imaginary octonions span a 7 dimension subspace octohions Odenoted Im O. The octonions can be thought of as octets or 8-tuples of real numbers. John, Thanks a lot for the detailed explanations.

These maximal orders were constructed by KirmseDickson and Bruck as follows. Also since the order does determine output, this gives a before and after quality if we build a length of time by successive octonion multiplication.

December 21, Erratum: Sierra, An application of the theories of Jordan algebras and Freudenthal triple systems to particles and strings, Class. Classification List Numbers portal. The string theorists also did a great publicity job for E8, although they seem to have lost interest in it.

Not being baeez, the nonzero elements of O do not form a group. From what I understand about octonions is that they are anti-associative for three oconions that are different excluding a real scaling factor.

## Mathematics > Rings and Algebras

Wolfram Wolfram Alpha blog Click the logo to buy. Johdanto matematiikan perusteisiin innokkaiden opiskelijoiden seurassa. PSL 2,O does exist: And even all these structures combined are just a totally minuscule portion of the string theory’s wisdom, much like John Baez’s knowledge of string theory is an infinitesimal fraction of the knowledge of a good graduate student.

A convenient mnemonic for remembering the octonione of unit octonions is given by the diagram, which represents the multiplication table of Cayley and Graves. First, you get a normed division algebra in dimension n if and only if you can find an n-dimensional spinor representation of Spin n.

Bronwin; and on quaternions, Philos. The table can be summarized as follows: Only time will tell.

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Zathras, This has nothing to do with rigorous vs. Here we describe them and their relation to Clifford algebras and spinors, Bott periodicity, projective and Lorentzian geometry, Jordan algebras, and the exceptional Lie groups. Every octonion is a real linear combination of the unit octonions:.