diff --git a/index.html b/index.html index 1ad7d80..d5a52e2 100644 --- a/index.html +++ b/index.html @@ -137,7 +137,7 @@

The Spectrum of a Tensor Field

\end{align} \]

There is no need to know these values when getting the product tables \(X_{i}X_{j}\).

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Shankland (1970) applies the Faddeev - LeVerrier algorithm, or rather its advanced variant extended to tackle multiple eigenvalues, see e.g. Helmberg and Wagner (1993). Note also that here we do not have eigenvectors in a traditional sense, they are weighted sums of the basis \(X_{i}\), not some matrix columns.

+

Shankland (1970) applies the Faddeev - LeVerrier algorithm, or rather its advanced variant extended to tackle multiple eigenvalues, see e.g. Helmberg and Wagner (1993). Here there are no eigenvectors in a traditional sense, they are weighted sums of the basis \(X_{i}\), not some matrix columns.

K.J. Barnes (1963) seeks the spectrum differently, with the matrix projection operators.

@@ -175,7 +175,7 @@

Why Shankland?

To sum up, we are given a field with tensor/spinor indices and their permutation symmetries. The author shows how to build a Lorentz-invariant operator which may serve as a quadratic form for the field. The invented (discovered?!) machinery allows to control a spin content of the field, defined as the eigenvalue multiplicities of the general element of the field’s algebra. One test of this formalism confirms that removing spin 0 from a vector field leads to “apesanteur” \(A\) aka vector potential.

-

Considering a massive literature around group theory, irreducible representations, angular momentum, higher spin field theories, spin projection operators, tensors, spinors, Weyl, Wigner, Weinberg… Shankland’s system is the only one I can really follow.

+

Considering a massive literature around group theory, irreducible representations, angular momentum, higher spin field theories, spin projection operators, tensors, spinors, Weyl, Wigner, Weinberg… Shankland’s system is the only one I can really follow!

Sign the contract big boy... diff --git a/index.md b/index.md index 07d5386..735d495 100644 --- a/index.md +++ b/index.md @@ -135,7 +135,7 @@ $$ There is no need to know these values when getting the product tables $X_{i}X_{j}$. -[Shankland (1970)](https://aapt.scitation.org/doi/10.1119/1.1976018) applies [the Faddeev - LeVerrier algorithm](https://en.wikipedia.org/wiki/Faddeev%E2%80%93LeVerrier_algorithm), or rather its advanced variant extended to tackle multiple eigenvalues, see e.g. [Helmberg and Wagner (1993)](https://core.ac.uk/download/pdf/81192811.pdf). Note also that here we do not have eigenvectors in a traditional sense, they are weighted sums of the basis $X_{i}$, not some matrix columns. +[Shankland (1970)](https://aapt.scitation.org/doi/10.1119/1.1976018) applies [the Faddeev - LeVerrier algorithm](https://en.wikipedia.org/wiki/Faddeev%E2%80%93LeVerrier_algorithm), or rather its advanced variant extended to tackle multiple eigenvalues, see e.g. [Helmberg and Wagner (1993)](https://core.ac.uk/download/pdf/81192811.pdf). Here there are no eigenvectors in a traditional sense, they are weighted sums of the basis $X_{i}$, not some matrix columns. [K.J. Barnes (1963)](https://spiral.imperial.ac.uk/bitstream/10044/1/13413/2/Barnes-KJ-1963-PhD-Thesis.pdf) seeks the spectrum differently, with the matrix projection operators. @@ -171,7 +171,7 @@ It is tough to read this literature, and the results may not always justify the To sum up, we are given a field with tensor/spinor indices and their permutation symmetries. The author shows how to build a Lorentz-invariant operator which may serve as a quadratic form for the field. The invented (discovered?!) machinery allows to control a spin content of the field, defined as the eigenvalue multiplicities of the general element of the field's algebra. One test of this formalism confirms that removing spin 0 from a vector field leads to "apesanteur" $A$ aka vector potential. -Considering a massive literature around group theory, irreducible representations, angular momentum, higher spin field theories, spin projection operators, tensors, spinors, Weyl, Wigner, Weinberg... **Shankland's system is the only one I can really follow.** +Considering a massive literature around group theory, irreducible representations, angular momentum, higher spin field theories, spin projection operators, tensors, spinors, Weyl, Wigner, Weinberg... **Shankland's system is the only one I can really follow!**
Sign the contract big boy...