Take the group of all Translation in .
Let's see how the generator of this group is the derivative operator:
The way to think about this is:
So let's take the exponential map:
and we notice that this is exactly the Taylor series of around the identity element of the translation group, which is 0! Therefore, if behaves nicely enough, within some radius of convergence around the origin we have for finite :
This example shows clearly how the exponential map applied to a (differential) operator can generate finite (non-infinitesimal) Translation!
SVG 1.2 by Ciro Santilli 37 Updated 2025-07-16
Dropped in favor of SVG 2.
Originally done with (neutral) silver atoms in 1921, but even clearer theoretically was the hydrogen reproduction in 1927 by T. E. Phipps and J. B. Taylor.
Video 1.
The Stern-Gerlach Experiment by Educational Services, Inc (1967)
Source. Featuring MIT Professor Jerrold R. Zacharias. Amazing experimental setup demonstration, he takes apart much of the experiment to show what's going on.
SARS-CoV-2 cell entry by Ciro Santilli 37 Updated 2025-07-16
Video 1.
Model of Membrane Fusion by SARS CoV-2 Spike Protein by clarafi (2020)
Source.
Atomic orbital by Ciro Santilli 37 Updated 2025-07-16
In the case of the Schrödinger equation solution for the hydrogen atom, each orbital is one eigenvector of the solution.
Remember from time-independent Schrödinger equation that the final solution is just the weighted sum of the eigenvector decomposition of the initial state, analogously to solving partial differential equations with the Fourier series.
This is the table that you should have in mind to visualize them: en.wikipedia.org/w/index.php?title=Atomic_orbital&oldid=1022865014#Orbitals_table

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