Atomic and Molecular Physics

The radical redefinition of the landscape of physics that followed the contributions of Niels Bohr and Werner Heisenberg at the start of the 20th century led to plethora [of] new perspectives on age-old metaphysical questions on determinism and the nature of reality. The main contention of this article is that the work of Gilbert Simondon - whose magnum opus possesses a scope uniting the most basic philosophical concerns with the most recent breakthroughs in natural sciences - is highly relevant for (...) an adequate understanding of the split between determinism and indeterminism, as well as the underlying presuppositions which have driven some influential contributions to this topic. To this end, the article shows that the more deterministic interpretation of quantum mechanics offered by David Bohm and Louis de Broglie proves to be a valuable reference point for a more precise use and understanding of Simondon'ss transductive logic - especially when its philosophical lapses are considered closely. Finally, following the considerations of both thinkers, we aim at a more precise reconsideration of the stakes of indeterminism in modern physics, as well as a restructuration of what is often understood as a polarization. (shrink)

The fine-structure constant, which determines the strength of the electromagnetic interaction, is briefly reviewed beginning with its introduction by Arnold Sommerfeld and also includes the interest of Wolfgang Pauli, Paul Dirac, Richard Feynman and others. Sommerfeld was very much a Pythagorean and sometimes compared to Johannes Kepler. The archetypal Pythagorean triangle has long been known as a hiding place for the golden ratio. More recently, the quartic polynomial has also been found as a hiding place for the golden ratio. The (...) Kepler triangle, with its golden ratio proportions, is also a Pythagorean triangle. Combining classical harmonic proportions derived from Kepler’s triangle with quartic equations determine an approximate value for the fine-structure constant that is the same as that found in our previous work with the golden ratio geometry of the hydrogen atom. These results make further progress toward an understanding of the golden ratio as the basis for the fine-structure constant. (shrink)

I defend an analog of probabilism that characterizes rationally coherent estimates for chances. Specifically, I demonstrate the following accuracy-dominance result for stochastic theories in the C*-algebraic framework: supposing an assignment of chance values is possible if and only if it is given by a pure state on a given algebra, your estimates for chances avoid accuracy-dominance if and only if they are given by a state on that algebra. When your estimates avoid accuracy-dominance (roughly: when you cannot guarantee that other (...) estimates would be more accurate), I say that they are sufficiently coherent. In formal epistemology and quantum foundations, the notion of rational coherence that gets more attention requires that you never allow for a sure loss (or “Dutch book”) in a given sort of betting game; I call this notion full coherence. I characterize when these two notions of rational coherence align, and I show that there is a quantum state giving estimates that are sufficiently coherent, but not fully coherent. (shrink)

Cartea abordează bazele fenomenlogice din fizica atomică, fizica nucleară, radioactivitatea, fizica particulelor, fisiunea, fuziunea și energia nucleară. Conținutul oferă o perspectivă modernă a domeniului, simultan cu o retrospectivă istorică a dezvoltării sale. Fiecare capitol pune accent pe explicațiile fizice ale fenomenelor, ocurența naturală, măsurare, și utilizarea practică a fenomenelor respective. CUPRINS: Fizica atomică - Natura atomică a materiei - - Ipoteze atomice - - Proprietățile atomilor - - - Proprietăți nucleare - - - Masa - - - Forma și dimensiunea (...) - - - Dezintegrarea radioactivă - - - Momentul magnetic - - - Nivelurile energetice - - - Valența și comportamentul legăturilor - - - Stări - - Imagistica atomică - - Structura atomului - - - Particule subatomice - - - Nucleul - - - Norul de electroni Atomul și cuanta - Descoperirea nucleului atomic - Descoperirea electronului - - Descoperirea - Spectroscopia atomică - Linii spectrale - - Teorie - - Atomii - - Linii spectrale - - - Tipuri de spectre de linii - Modelul Bohr al atomului - - Origine - - Mărimea relativă a atomilor (Raza atomilor) - - - Definiții - - - Raze atomice măsurată empiric - - - Raze atomice calculate - - Nivele energetice cuantificate: Undele electronilor (Nivele energetice) - - - Explicație - - - Tranziții ale nivelelor de energie - Mecanica cuantică - - Istorie - - Formulări matematice - Principiul corespondenței - - Mecanica cuantică Nucleul atomic și radioactivitatea - Razele X - - Istorie - - Proprietăți - - - Interacțiunea cu materia - - Producere - - - Detectoare - - - Utilizări medicale - Radiații alfa, beta și gama - Radiații ionizante - - Radiația alfa - - - Utilizări - - Radiația beta - - - Utilizări - - Radiația gama - - - Utilizări - Nucleul atomic - - Structura nucleară - - Compoziție și formă - - Forțe - - - Forța nucleară slabă - - - Forța nucleară tare - Izotopi - - Izotop vs. nuclid - - Definiția - - Notație - - Izotopi radioactivi, primordiali și stabili - Dezintegrarea radioactivă - - Baza teoretică a fenomenelor de dezintegrare - - Apariție și aplicații - - Originea nuclizilor radioactivi - Timpul de înjumătățire - - Detectoare de radiații (Detectoare de particule) - - Detectoare de ionizare gazoasă - - Detector de urme nucleare în stare solidă - - Calorimetre - - Detectoare plate cu microcanale - - Detectarea neutronilor - - Detectoare moderne - - - Detector ermetic - - Instrumente de protecție împotriva radiațiilor - - - Instrumente instalate - - - Instrumente portabile - - Detectoare de particule în cercetare - Transmutarea elementelor (Transmutarea nucleară) - - Istorie - - - Alchimie - - - Fizica modernă - - Transmutarea naturală (Transmutarea în univers) - - Transmutarea artificială (Transmutarea deșeurilor nucleare) - - - Tipurile de reactoare - - - Tipuri de combustibil - - - Motivația din spatele transmutării - - - Produse de fisiune cu durată lungă de viață - Izotopi radioactivi (Radionuclizi) - - Origine - - - Natural - - - Fisiunea nucleară - - - Sintetic - - Utilizări - Datarea radiometrică - - Bazele datării radiometrice - - - Dezintegrarea radioactivă - - - Precizia datării radiometrice - - - Temperatura de închidere - - - Ecuația vârstei - - Datarea cu carbon - - - Detaliile fizice și chimice - - - Principii - - - Considerații privind datarea - - Datarea cu uraniu - - - Metoda de datare cu uraniu-plumb - - - Metoda de datare cu uraniu-toriu - Efectele radiațiilor asupra oamenilor - - Efectele asupra sănătății - - Expunerea la radiații - - - Expunerea profesională - - - Expunerea publica - - - Zborul în spațiu - - - Transportul aerian - - - Semne de avertizare privind pericolele de radiație - - Dozarea radiațiilor - - - Măsurare Fizica particulelor - Istoria - Modelul Standard - Fizica particulelor experimentală - Obiecții - Politici publice - Particule elementare - - Particule elementare - - - Fermioni - - - - Cuarci - - - Cuarci - - - - Leptoni - - - Leptoni - - - Bosoni - - - Particule ipotetice - - Particule compuse - - - Hadroni - - - Barioni - - - Mezoni - - - Nuclee atomice - - - Atomi - - - Molecule - - Substanțe condensate - - Alte particule - - Extensii ale Modelului Standard - - - Marea unificare - - - Supersimetria - - - Teoria corzilor - - - Teoria preonilor - Protoni - Neutroni - - Istoric - - - Evoluția actuală - Electron - - Clasificare - - Proprietăți fundamentale - Cuarci - Fotoni - Gluoni - Bosoni W și Z - - Bosonul Higgs - Neutrino - - Neutrino, noul sistem de comunicații - - Telefonul – particulă - - Comunicații cu submarinele - - Mesaje pentru călătoria în timp - Fizica acceleratorilor - - Accelerarea și interacțiunea particulelor cu structuri RF - - Dinamica fluxului - - Coduri de modelare - - Diagnosticările fluxului - - Toleranțele mașinii Fisiunea și fuziunea nucleară - Istorie - - Descoperirea nucleului - - Descoperirea neutronului - - Câmpul bozonic - - Mezoni - Fisiunea nucleară - - Mecanismul - - Reactoare de fisiune nucleară - - - Mecanism - - - - Fisiunea - - - - Generarea de căldură - - - - Răcirea - - - - Controlul reactivității - - - - Generarea de energie electrică - - Reactoare nucleare cu apă grea presurizată - CANDU - - - Scopul utilizării apei grele - - - Avantaje și dezavantaje - - - Emisiile de tritiu - - - Reactorul CANDU - - - Centrala Nucleară de la Cernavodă - - - - Reactoarele - - - - Incidente - - Plutoniu - - - Proprietăți fizice - - Reactoare nucleare reproducătoare - - - Eficiența combustibilului și tipurile de deșeuri nucleare - - - Raportul de conversie, pragul de rentabilitatea, raportul de reproducere, timpul de dublare și arderea - - - Tipuri de reactoare reproducătoare - - Energia de fisiune - - - Centrale nucleare - - - Probleme de mediu - - - Energia nucleară în România - - Echivalența masă-energie în reacțiile nucleare - - - Istorie - - - Exemplu practic - - - Eficiența - Fuziunea nucleară - - Procesul - - Controlul fuziunii (Energia de fuziune) - - - Descriere - - - - Mecanism - - - - Secțiunea transversală - - - - Criteriul Lawson - - - - Produs triplu: densitate, temperatură, timp - - - - Comportamentul plasmei - - - - Captarea energiei Probleme nerezolvate - Fizica nucleară - Fizica particulelor / Fizica energiilor înalte Referințe Despre autor - Nicolae Sfetcu - - De același autor - - Contact Editura - MultiMedia Publishing . 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What is the meaning of the wave-function? After almost 100 years since the inception of quantum mechanics, is it still possible to say something new on what the wave-function is supposed to be? Yes, it is. And Shan Gao managed to do so with his newest book. Here we learn what contemporary physicists and philosophers think about the wave-function; we learn about the de Broglie-Bohm theory, the GRW collapse theory, the gravity-induced collapse theory by Roger Penrose, and the famous PBR (...) theorem; we learn about Schrödinger's original idea that the wave-function represents charge densities; we learn about the notorious measurement problem and its consequences; we learn about the challenges to find a consistent relativistic quantum theory; and we learn, of course, Gao's own suggestion for the status of the wave-function. Above all, Gao shows us the significance of protective measurements for our search of the ontology of quantum mechanics. Still not widely recognized among physicists and philosophers, protective measurements let us look deeper into quantum mechanics. For Gao this is the main tool to settle the issue on the ontological status of the wave-function: the wave-function is real because one can measure it. (shrink)

This essay introduces the transcription and translation of Paul Feyerabend's "Der Begriff der Verständlichkeit in der modernen Physik" [The concept of intelligibility in modern physics] (1948), which is an early essay written by Paul Feyerabend in 1948 on the topic of intelligibility (Verständlichkeit) and visualizability (Anschaulichkeit) of physical theories. The existence of such essay was likely. It is listed in his bibliography as his first publication. Yet the content of the essay was unknown, as no original or copy is extant (...) in Feyerabend's Nachlass and no known published version was available to the community—until now. The essay has both historical and philosophical interest: it is, as far as our current knowledge goes, Feyerabend's earliest extant publication. It documents Feyerabend's philosophical interest as a physicist-to-be, in what he himself called his “positivist” phase; and it gives a rare if fragmentary insight into the early discussions of the ‘Third Vienna Circle’ and, more generally, the philosophical culture of discussion in Vienna. (shrink)

Arnold Sommerfeld introduced the fine-structure constant that determines the strength of the electromagnetic interaction. Following Sommerfeld, Wolfgang Pauli left several clues to calculating the fine-structure constant with his research on Johannes Kepler's view of nature and Pythagorean geometry. The Laplace limit of Kepler's equation in classical mechanics, the Bohr-Sommerfeld model of the hydrogen atom and Julian Schwinger's research enable a calculation of the electron magnetic moment anomaly. Considerations of fundamental lengths such as the charge radius of the proton and mass (...) ratios suggest some further foundational interpretations of quantum electrodynamics. (shrink)

Gregor Schiemann führt allgemeinverständlich in das Denken dieses Physikers ein. Thema sind die Erfahrungen und Überlegungen, die Heisenberg zu seinen theoretischen Erkenntnissen geführt haben, die wesentlichen Inhalte dieser Erkenntnisse sowie die Konsequenzen, die er daraus für die Geschichte der Physik und das wissenschaftliche Weltbild gezogen hat. Heisenbergs Vorstellungswelt durchzieht durch ein Spannungsverhältnis, das heute noch das Denken vieler Wissenschaftlerinnen und Wissenschaftler bewegt. Er ist um ein umfassendes Verständnis der Naturprozesse bemüht, zugleich aber von der Berechenbarkeit und Beherrschbarkeit von Phänomenen auch (...) dann schon fasziniert, wenn die zugrunde liegenden Prozesse erst teilweise verstanden sind. Aus der Geschichte der Physik zieht er die wirkungsreiche Lehre, daß sich die naturwissenschaftliche Erkenntnis nicht kontinuierlich, sondern sprunghaft in Form von Revolutionen entwickelt. Die Reichweite des physikalischen Wissens begrenzt er in einer Schichtentheorie der Welt, nach der die komplexen Phänomene des Lebens nicht allein durch die Wechselwirkungen zwischen ihren Bestandteilen erklärt werden können. Der zunehmenden Technisierung der Welt steht Heisenberg kritisch gegenüber. Seiner Zeit weit voraus, glaubt er, daß die Technisierung der Welt eine epochal neue Stufe erreicht habe, in der der Mensch „nur noch sich selbst“ gegenüberstehe. (shrink)

Pierre Gassendi was a major factor in the revival of Epicureanism in early modern philosophy, not only through his contribution to the restoration and criticism of Epicurean texts, but also by his adaptation of Epicurean ideas in his own philosophy, which was itself influential on such important figures of early modern philosophy as Hobbes, Locke, Newton, and Boyle (to name just a few). Despite his vigorous defense of certain Epicurean ideas and ancient atomism, Gassendi goes to great lengths to differentiate (...) his philosophy from Epicureanism on certain key points. In this paper I argue that those key points on which Gassendi rejects and and criticizes the Epicurean view, such as the immortality of the soul and divine creation of the cosmos, are central not only to Epicureanism, but also to Gassendi's own philosophy. In order to see Gassendi's philosophy for what it is, and understand its role in the history of natural theology, we need accept and understand better why he rejected the central theses of Epicureanism. (shrink)

تجلت المعالجة الفيزيائية المعاصرة لموضوع الاتصال في نظريتين كبريتين تقاسمتا البحث في الظواهر الطبيعية منذ بداية القرن العشرين: إحداهما نظريــة النسبية (الخاصـة والعامـة)، والأخرى نظرية الكم. وبينما تُعيد النسبية الخاصة صياغة القوانين الأساسية للحركة على نحو أدق مما قدمه نيوتن، تتجه النسبية العامة إلى تعليل خواص المادة على النطاق الواسع، أي على مستوى الكون الأكبر، حيث النجوم والكواكب وحركاتها التجاذبية. أما نظرية الكمّ فتًعلل خواص المادة على النطاق الضيق جدًا، أي على مستوى الكون الذري. وليس هناك فيما يبدو أية رابطة (...) بين النسبية العامة والكم، اللهم إلا في أساسهما المشترك وهو النسبية الخاصة. ومن ناحية أخرى، بينما تنجح النسبية في تحطيم الأطر المطلقة التي افترض نيوتن أن قوانين الطبيعة تعمل بمقتضاها، وهي الزمان والمكان، تُحرز نظرية الكمَّ نجاحًا مماثلاً في تفتيت عالم الذرة الذي ظنه نيوتن مصمتًا لا داخل له. والحق أنها لمهمة شاقة أن نعرض في بحثٍ واحد لنظريتين أثارتا من المشكلات الفلسفية أكثر مما اضطلعتا بحله. ولكننا مع ذلك سنحاول تتبع الخطوط الرئيسة لكلتيهما، تدفعنا رغبة مُلحة في الحصول على إجابة شافية عما إذا كان الاتصال قائمًا في الطبيعة أم لا. (shrink)