Matrix exponential by Ciro Santilli 40 Updated 2025-07-16
Is the solution to a system of linear ordinary differential equations, the exponential function is just a 1-dimensional subcase.
Note that more generally, the matrix exponential can be defined on any ring.
The matrix exponential is of particular interest in the study of Lie groups, because in the case of the Lie algebra of a matrix Lie group, it provides the correct exponential map.
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How (and why) to raise e to the power of a matrix by 3Blue1Brown (2021)
Source.
This is how you transform the Lagrangian into the Hamiltonian.
Subtle is the Lord by Abraham Pais (1982) chapter 4 "Entropy and Probability" mentions well how Boltzmann first thought that the second law was an actual base physical law of the universe while he was calculating numerical stuff for it, including as late as 1872.
But then he saw an argument by Johann Joseph Loschmidt that given the time reversibility of classical mechanics, and because they were thinking of atoms as classical balls as in the kinetic theory of gases, then there always exist a valid physical state where entropy decreases, by just reversing the direction of time and all particle speeds.
So from this he understood that the second law can only be probabilistic, and not a fundamental law of physics, which he published clearly in 1877.
Elon Musk by Ciro Santilli 40 Updated 2025-07-16
Musk is a truly ambivalent personality. Some points are very good. Some are very bad.
Respect on the technical side by Ciro Santilli.
But the way he treated his first wife Justine Musk, is very very weird, incomprehensible: www.marieclaire.com/sex-love/a5380/millionaire-starter-wife/
Positive Cirocoins for possibly going to reverse Twitter's unfair Trump ban if his Twitter acquisition goes through:
Negative Cirocoins for according to Wikipedia:
Within the merged company [Thiel's Confinity + Elon's X.com], Musk returned as CEO. Musk's preference for Microsoft software over Unix created a rift in the company and caused Thiel to resign.
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The REAL Reason Why Tesla Made All Patents Open-Source by The not so boring Man (2021)
Source. Supercut from various interviews/presentations in which Elon saying that Tesla has open source patents and pro open source stuff. Can we trust it? Maybe.
Xavier Niel by Ciro Santilli 40 Updated 2025-07-16
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Xavier Niel, Iliad - Free: Je suis un casseur de monopoles by DECIDEURSTV (2011)
Source. Title translation: "I'm a hunter of monopolies".

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