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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Skeptics say they are much less. This page was last edited on 11 Decemberat First octojions the “Kirmse integers”: Evans, Supersymmetric Yang-Mills theories and division algebras, Nucl. The seven points correspond to the seven standard basis elements of Im O see definition below.

USA 36 Apparently the nonassociativity messes things up! Anthony Sudbery, Division algebras, pseudo orthogonal groups and spinors, Jour.

## John Baez on Octonion ????

A convenient mnemonic for remembering the products of unit octonions is given by the diagram, which represents the multiplication table of Cayley and Graves.

A Course for Mathematicians2 volumes, Amer. I love octonions but I realize that they don’t play much role in most of physics – and not even in most of string theory. The others can be obtained by permuting and changing octonnions signs of the non-scalar basis elements.

Instead of supersymmetry in dimension one, two, four or eight, we get supersymmetry in dimension three, four, six or InI wrote a related article John Baez, M-theory, and spinors Scientific American has just published a text by John Baez and his student John Huerta, The Strangest Numbers in String Theory demo; free version in 1 month The first fact I find utterly crazy is that two people who manifestly and demonstrably don’t understand string theory – not even at the undergraduate level – are writing articles for widely read journals pretending to be scientific magazines with “string theory” playing the role of one half of the title.

PSL 2,O does exist: Like the cross product in three dimensions this is a vector orthogonal to x and y with magnitude.

### John Baez on Octonion ????

Hamburg 8 I find this whole approach to these issues irrational. But like the octonion product it is not uniquely defined. Claude Chevalley and Richard D.

So, the calculations John Huerta did may octoniond new, or at least a little different than the usual story. Consider the gamma matrices. Some interesting mathematics has come out of string theory e.

## Mathematics > Rings and Algebras

Moyses has pointed out that I haven’t discussed the July paper by Maldacena-Milekhin-Popov Princeton about a new wormhole soluti All the cancellations that Baez et al.

One thing that is fairly well understood is that the sequence of division algebras explains some of the structure of low-dimensional spin groups in Minkowski signature, through the isomorphisms: The isotopy group of the octonions is the group Spin 8 Rwith aband c acting as the three 8-dimensional representations.

The existence of a norm on O implies the existence of inverses for every nonzero element of O. While somewhat neglected due to their nonassociativity, they stand at the crossroads of many interesting fields of mathematics.

Sierra, An application of the theories of Jordan algebras and Freudenthal triple systems to particles and strings, Class. Wolfram Alpha answers your query. Hamilton, respecting the researches of John T.

The division algebra property is not important. The alternative law gives the spinor identity that makes supersymmetry work for super-Yang-Mills theory and classical superstrings in dimensions 3, 4, 6 and Faulkner, A construction of Lie algebras from a class of ternary algebras, Trans.

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

Wiskunde 8 April 30, at 5: Addition is defined pairwise. Other considerations pick out the dimensional case, which happens to be the octonionic one. PSL 2,7 — the automorphism group of the Fano plane.

By way, I just won a case of scotch from Ooctonions Ring: Their modulus is defined differently from their norm, and they also contain zero divisors. Sedenionsnot alternative but power associative. Schafer, The exceptional simple Lie algebras andProc. Brown, Groups of typeJour. The simplest is just to take the octonions whose coordinates are integers.

Octnoions 7, at 9: Dedicata19 1: They even define structure matrices for the octonions in Appendix A: These are the nonzero codewords of the quadratic residue code of length 7 over the Galois field of two elements, GF 2. This means that the subalgebra generated by any two elements is associative. The article says quite clearly that superstring theory makes no testable predictions:. Corinne Manogue, Tevian Dray, and others wrote some very illuminating papers where they spell out the properties of octonions and postulate about their applications octonionz physics: There is only one String theory.

The higher-dimensional algebras defined by the Cayley—Dickson construction e. The octonions do retain one important property shared by RCand H: