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Jun 3, 2023 at 1:27 answer added krm2233 timeline score: 1
Sep 17, 2017 at 23:36 answer added Kimball timeline score: 1
Sep 17, 2017 at 15:00 comment added anon The motivation for constructing the quaternions is more geometric than purely algebraic. Hamilton wanted 3D rotations the way complex numbers yield 2D rotations, so wanted a 3D number system equipped with a multiplicative norm. However, the norm didn't work out to be multiplicative... until he realized that $ij$ (the product of $i$ and the new $j$) must be linearly independent, i.e. jut out in a 4th dimension. Then it becomes more evident the relations they must satisfy in order for multiplicativity to be achieved, after which we get 3D and 4D rotations via quaternions.
Sep 16, 2017 at 23:27 comment added user451844 youtube.com/watch?v=3BR8tK-LuB0 might be a good start ?
Sep 16, 2017 at 23:25 comment added J. M. ain't a mathematician "cannot solve it without" - that's a bit strict, I think. One could certainly choose to work instead with certain $4\times 4$ matrices with properties that allow that system to be isomorphic to the quaternions. The quaternions just happen to be a convenient and compact representation. And as already mentioned, the dual numbers are a very useful system. Have a look at the "split-complex numbers" as well.
Sep 16, 2017 at 23:19 comment added Tyberius There actually is an interesting number system obtain by defining a new number $\epsilon^2=0$. These are called the [Dual Numbers])(en.wikipedia.org/wiki/Dual_number)
Sep 16, 2017 at 23:14 review First posts
Sep 16, 2017 at 23:17
Sep 16, 2017 at 23:09 history asked ajd138 CC BY-SA 3.0