Open System – Ark's blog https://arkadiusz-jadczyk.eu/blog Physics without frontiers Sun, 22 Mar 2026 11:20:36 +0000 en-US hourly 1 https://wordpress.org/?v=6.9.4 https://arkadiusz-jadczyk.eu/blog/wp-content/uploads/2025/11/cropped-Parabolic-Quantum-FractalLogo-32x32.jpg Open System – Ark's blog https://arkadiusz-jadczyk.eu/blog 32 32 Recovery https://arkadiusz-jadczyk.eu/blog/2026/03/recovery/?utm_source=rss&utm_medium=rss&utm_campaign=recovery https://arkadiusz-jadczyk.eu/blog/2026/03/recovery/#comments Sun, 22 Mar 2026 10:20:49 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3812 This post is an attempt to explain my recent long silence. Over the past few months I have been in a kind of “construction period,” slowly rebuilding my working environment and trying to create a space where I can think … Continue reading →

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]]> https://arkadiusz-jadczyk.eu/blog/2026/03/recovery/feed/ 3 3812 Exterior algebra https://arkadiusz-jadczyk.eu/blog/2026/01/exterior-algebra/?utm_source=rss&utm_medium=rss&utm_campaign=exterior-algebra https://arkadiusz-jadczyk.eu/blog/2026/01/exterior-algebra/#comments Sun, 18 Jan 2026 18:09:28 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3787 Geometric algebra was not born in an ivory tower; it grew out of three very human lives, each marked by faith, doubt, and an almost mystical hunger for structure. ​ The quiet mystic: Grassmann Hermann Grassmann was a provincial schoolteacher, … Continue reading →

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]]> https://arkadiusz-jadczyk.eu/blog/2026/01/exterior-algebra/feed/ 5 3787 Kronecker generalized deltas and Levi-Civita epsilons https://arkadiusz-jadczyk.eu/blog/2026/01/kronecker-generalized-deltas-and-levi-civita-epsilons/?utm_source=rss&utm_medium=rss&utm_campaign=kronecker-generalized-deltas-and-levi-civita-epsilons https://arkadiusz-jadczyk.eu/blog/2026/01/kronecker-generalized-deltas-and-levi-civita-epsilons/#comments Fri, 09 Jan 2026 10:08:01 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3777 My last post “It’s all about permutations” was a complete failure. Really very bad. I copied, without much thinking, some formulas from “Mathematical Handbook For Scientists And Engineers“, Granino A. Korn and Theresa M. Korn, Dover 2000, and it was … Continue reading →

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]]> https://arkadiusz-jadczyk.eu/blog/2026/01/kronecker-generalized-deltas-and-levi-civita-epsilons/feed/ 17 3777 It’s all about permutations https://arkadiusz-jadczyk.eu/blog/2025/12/its-all-about-permutations/?utm_source=rss&utm_medium=rss&utm_campaign=its-all-about-permutations https://arkadiusz-jadczyk.eu/blog/2025/12/its-all-about-permutations/#comments Sun, 28 Dec 2025 11:19:33 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3757 Permutations appear whenever “things are the same, but in a different order.” That simple idea hides a powerful engine that underlies physics, geometry, information, and even the notion of identity itself. In quantum mechanics, identical particles do not carry little … Continue reading →

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]]> https://arkadiusz-jadczyk.eu/blog/2025/12/its-all-about-permutations/feed/ 10 3757 Densities https://arkadiusz-jadczyk.eu/blog/2025/12/densities/?utm_source=rss&utm_medium=rss&utm_campaign=densities https://arkadiusz-jadczyk.eu/blog/2025/12/densities/#comments Sun, 21 Dec 2025 14:58:42 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3725 This post introduces “densities”. There is a very nice book, available on arxiv, by Sean M. Carroll: “Lecture Notes on General Relativity“. There, on p. 52, Carroll writes “… we don’t like tensor densities, we like tensors.” Well, I do … Continue reading →

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]]> https://arkadiusz-jadczyk.eu/blog/2025/12/densities/feed/ 56 3725 Tensors on a picnic https://arkadiusz-jadczyk.eu/blog/2025/12/tensors-on-a-picnic/?utm_source=rss&utm_medium=rss&utm_campaign=tensors-on-a-picnic https://arkadiusz-jadczyk.eu/blog/2025/12/tensors-on-a-picnic/#comments Sun, 14 Dec 2025 17:26:00 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3701 This series of posts is meant as a “gentle introduction to …”. It’s so gentle that some readers may even find it boring. They might say, “All this is well known—get to the point!” But I can’t think of another … Continue reading →

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]]> https://arkadiusz-jadczyk.eu/blog/2025/12/tensors-on-a-picnic/feed/ 21 3701 Tensors are geometric objects https://arkadiusz-jadczyk.eu/blog/2025/12/tensors/?utm_source=rss&utm_medium=rss&utm_campaign=tensors https://arkadiusz-jadczyk.eu/blog/2025/12/tensors/#comments Wed, 10 Dec 2025 16:17:49 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3658 Originally, while writing the previous post, I was convinced that this one should be devoted to the Grassmann (or exterior) algebra.  I even began drafting it and managed about half a page before realizing that, if the promise of a … Continue reading →

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]]> https://arkadiusz-jadczyk.eu/blog/2025/12/tensors/feed/ 16 3658 Conformal structure – until the puppy grows up https://arkadiusz-jadczyk.eu/blog/2025/12/conforma-structure-until-the-puppy-grows-up/?utm_source=rss&utm_medium=rss&utm_campaign=conforma-structure-until-the-puppy-grows-up https://arkadiusz-jadczyk.eu/blog/2025/12/conforma-structure-until-the-puppy-grows-up/#comments Sun, 07 Dec 2025 12:34:03 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3644 On my other blog, I promised Anna—the ever‑curious Reader—that I would finally tackle the subject of conformal structure. So here it begins: a gentle introduction to a concept that admits many gateways. Precise definitions abound online, of course, and one … Continue reading →

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]]> https://arkadiusz-jadczyk.eu/blog/2025/12/conforma-structure-until-the-puppy-grows-up/feed/ 26 3644 Growing Out of the Sandbox https://arkadiusz-jadczyk.eu/blog/2025/12/growing-out-of-the-sandbox/?utm_source=rss&utm_medium=rss&utm_campaign=growing-out-of-the-sandbox https://arkadiusz-jadczyk.eu/blog/2025/12/growing-out-of-the-sandbox/#respond Tue, 02 Dec 2025 13:24:54 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3629 On my other blog, I spent quite some time exploring a simplified universe—one defined by just one spatial and one temporal dimension. When space is only one-dimensional, the possibilities for motion are strictly limited: light can travel either to the … Continue reading →

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]]> https://arkadiusz-jadczyk.eu/blog/2025/12/growing-out-of-the-sandbox/feed/ 0 3629 Blog reincarnation with analytic idealism https://arkadiusz-jadczyk.eu/blog/2025/11/blog-reincarnation-with-analytic-idealism/?utm_source=rss&utm_medium=rss&utm_campaign=blog-reincarnation-with-analytic-idealism https://arkadiusz-jadczyk.eu/blog/2025/11/blog-reincarnation-with-analytic-idealism/#respond Sun, 30 Nov 2025 16:58:28 +0000 https://arkadiusz-jadczyk.eu/blog/?p=3624 I am reincarnating my old blog. It is a kind of rebirth. And, in Bernardo Kastrup’s analytic idealism, a newborn is not a tabula rasa. Kastrup does not see reincarnation as a literal soul moving into a new body. Instead, … Continue reading →

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