Timeline for Einstein Summation Problem
Current License: CC BY-SA 4.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Nov 29, 2022 at 20:13 | comment | added | Ghoster | The important thing to understand is why $a_1b_1+a_2b_2+a_3b_3$ gives a quantity that is invariant under rotations, but $a_1b_1+a_1b_2+\dots+a_3b_2+a_3b_3$ does not. A similar argument applies to Lorentz transformations. Tensor contractions are defined in a way that ensures they produce other tensors. | |
| Nov 29, 2022 at 18:32 | answer | added | J. Murray | timeline score: 2 | |
| Nov 29, 2022 at 18:31 | comment | added | Ghoster | Think about $\vec a\cdot\vec b=a_ib_i$ for 3D Cartesian vectors. | |
| Nov 29, 2022 at 18:28 | comment | added | Ghoster | en.wikipedia.org/wiki/Einstein_notation | |
| Nov 29, 2022 at 18:26 | history | asked | Nayeem1 | CC BY-SA 4.0 |