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What Exactly is Dirac’s Delta Function?

29 August 2025 at 12:51
Introduction: β€œConvenient Notation” In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a β€œconvenient notation” he referredΒ  to as a β€œdelta function” which he treated as a continuum analog to the discrete Kronecker delta.Β  The Kronecker delta is simply the indexed components of the identity operator in matrix algebra: [tex]\delta^j_k =\left\{\begin{array}{lcl}1&\text{ if }...

Fixing Things Which Can Go Wrong With Complex Numbers

By: PAllen
20 July 2025 at 12:55
Abstract This article will build on the hints about treating the complex numbers as a branched surface, briefly described and pictured in section 4.2 of https://www.physicsforums.com/insights/views-on-complex-numbers/#The-Radish. Using a particular set of conventions, all the problems described inΒ https://www.physicsforums.com/insights/things-can-go-wrong-complex-numbers/ Β can be removed, and the rules described there as applying only to reals generalized to complex numbers. A...

Series in Mathematics: From Zeno to Quantum Theory

8 November 2023 at 02:13
Introduction Series play a decisive role in many branches of mathematics. They accompanied mathematical developments from Zeno of Elea (##5##-th century BC) and Archimedes of Syracuse (##3##-th century BC), to the fundamental building blocks of calculus from the ##17##-th century on, up to modern Lie theory which is crucial for our understanding of quantum theory....
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