eBooks de Historia de la ciencia, página 10 de 61

Un Monde Sans Plastique : Des Solutions dAvenirLe plastique, autrefois symbole de progrès, est aujourdhui lun des plus grands défis environnementaux. "Un Monde Sans Plastique : Des Solutions dAvenir"

Niels Bohr (18851962) was a Danish physicist who played a key role in the development of atomic theory and quantum mechanics, he was awarded the Nobel Prize for Physics in 1922. First published in 1924, this second edition of a 1922 original contains three essays by Bohr dealing with the application of quantum theory to problems of atomic structure: the first essay is on the spectrum of hydrogen; the second is on the series spectra of the elements; the third is on the structure of the atom and the physical and chemical properties of the elements. The essays do not aim at a comprehensive treatment of their subjects, instead providing the reader with a more accessible, generalised viewpoint. This book will be of value to anyone with an interest in Bohrs contribution to physics.

« Le plateau central et ses volcans un Etna français » de Stanislas Meunier et Philippe Glangeaud est un ouvrage captivant qui plonge le lecteur au coeur de la géologie fascinante du Massif Central.

Neste momento crucial, em que a intersecção entre ciência, tecnologia e sociedade molda nosso futuro, Luiz Ricardo Mantovani da Silva nos oferece uma obra indispensável, com um olhar aguçado e a prof

Em Estrada para lugar nenhum , o jornalista, podcaster e crítico Paris Marx desafia as visões utópicas do Vale do Silício sobre o futuro do transporte. Desvendando as falhas nas promessas de carros a

Nel terzo volume della collana I manuali dellaspirante scienziato viene fornita una guida per orientarsi nel complesso mondo della gestione dei rifiuti alla luce delle recenti disposizioni riguardanti leconomia circolare.Paradossalmente la gestione dei rifiuti, importantissima nellottica della tutela dellambiente e del pianeta, e contemporaneamente uno degli argomenti che piu appassionano riflessioni, in particolare quelle socio-politiche e, nello stesso tempo, un tema nel quale la discussione di massa e caratterizzata da grande approssimazione, forte inconsapevolezza e, troppo spesso, solamente da affermazioni ideologiche e/o demagogiche destituite di alcun fondamento tecnico-scientifico.In questo manuale, lautore riesce a condensare, in poche pagine, molte delle conoscenze indispensabili per poter correttamente approcciare il tema, in particolare dal punto di vista della corretta gestione dei rifiuti e della buona pratica operativa ai fini dellattuazione dei principi delleconomia circolare

IN connexion with the discussion of the physical interpretation of the quantum theoretical methods developed during recent years, I should like to make the following general remarks regarding the principles underlying the description of atomic phenomena, which I hope may help to harmonise the different views, apparently so divergent, concerning this subject.The content of this paper is essentially the same as that of a lecture on the present state of the quantum theory delivered on Sept. 16, 1927, at the Volta celebration in Como. For a summary of the theory just previous to the development of the new methods the reader is referred to a lecture of the author, Atomic Theory and Mechanics, published in this periodical (NATURE, 116, 809; 1925).The rapid development which has taken place since has given rise to a considerable number of publications. The present paper is confined to a few references to recent articles which have a special bearing on the subject now under discussion.

IN a series of papers in this periodical the present writer has attempted to give the outlines of a theory of the constitution of atoms and molecules by help of a certain application of the Quantum theory of radiation to the theory of the nucleus atom. As the theory has been made a subject of criticism, and as experimental evidence of importance bearing on these questions has been obtained in the meantime, an attempt will be made in this paper to consider some points more closely.

Part of the ensuing Discourse about Light was written at the Desire of some Gentlemen of the Royal-Society, in the Year 1675, and then sent to their Secretary, and read at their Meetings, and the rest was added about twelve Years after to complete the Theory; except the third Book, and the last Proposition of the Second, which were since put together out of scatterd Papers. To avoid being engaged in Disputes about these Matters, I have hitherto delayed the printing, and should still have delayed it, had not the Importunity of Friends prevailed upon me. If any other Papers writ on this Subject are got out of my Hands they are imperfect, and were perhaps written before I had tried all the Experiments here set down, and fully satisfied my self about the Laws of Refractions and Composition of Colours. I have here publishd what I think proper to come abroad, wishing that it may not be translated into another Language without my Consent.The Crowns of Colours, which sometimes appear about the Sun and Moon, I have endeavoured to give an Account of; but for want of sufficient Observations leave that Matter to be farther examined. The Subject of the Third Book I have also left imperfect, not having tried all the Experiments which I intended when I was about these Matters, nor repeated some of those which I did try, until I had satisfied my self about all their Circumstances. To communicate what I have tried, and leave the rest to others for farther Enquiry, is all my Design in publishing these Papers.In a Letter written to Mr. Leibnitz in the year 1679, and published by Dr. Wallis, I mentiond a Method by which I had found some general Theorems about squaring Curvilinear Figures, or comparing them with the Conic Sections, or other the simplest Figures with which they may be compared. And some Years ago I lent out a Manuscript containing such Theorems, and having since met with some Things copied out of it, I have on this Occasion made it publick, prefixing to it an Introduction, and subjoining a Scholium concerning that Method. And I have joined with it another small Tract concerning the Curvilinear Figures of the Second Kind, which was also written many Years ago, and made known to some Friends, who have solicited the making it publick.In this Second Edition of these Opticks I have omitted the Mathematical Tracts publishd at the End of the former Edition, as not belonging to the Subject. And at the End of the Third Book I have added some Questions. And to shew that I do not take Gravity for an essential Property of Bodies, I have added one Question concerning its Cause, chusing to propose it by way of a Question, because I am not yet satisfied about it for want of Experiments.This new Edition of Sir Isaac Newtons Opticks is carefully printed from the Third Edition, as it was corrected by the Authors own Hand, and left before his Death with the Bookseller. Since Sir Isaacs Lectiones Optic, which he publickly read in the University of Cambridge in the Years 1669, 1670, and 1671, are lately printed, it has been thought proper to make at the bottom of the Pages several Citations from thence, where may be found the Demonstrations, which the Author omitted in these Opticks.

Niels Bohrs atomic theory of 1913 is one of the absolute highlights in the history of modern science. It was only with this work that physicists realized that quantum theory is an essential ingredient in atomic physics, and it was also only with this work that Rutherfords nuclear model dating from 1911 was transformed into a proper theory of atomic structure. In a longer perspective, Bohrs quantum atom of 1913 gave rise to the later Heisenberg-Schrodinger quantum mechanics and all its marvellous consequences. This book is a detailed account of the origin of the Bohr atom centred around his original scientific articles of 1913 which are here reproduced and provided with the necessary historical background. In addition to the so-called trilogy the three papers published in Philosophical Magazine also two other and less well-known yet important papers are included.The present work proceeds with a chapter outlining earlier ideas of atomic structure and tracing Bohrs route from his doctoral dissertation in 1911 over his stays in Cambridge and Manchester to the submission in April 1913 of the first part of the trilogy. The reproduction of Bohrs five articles is followed by notes and comments directly related to the texts, with the aim of clarifying some of the textual passages and to explicate names and subjects that may not be clear or well known. The reception of Bohrs radically new theory by contemporary physicists and chemists is discussed in a final chapter, which deals with the immediate reactions to Bohrs theory 1913-1915 mostly among British, German and American scientists.Historians of science have long been occupied with Bohrs atomic theory, which was the subject of careful studies in connection with its centenary in 2013. The present work offers an extensive source-based account of the original theory aimed at a non-specialist audience with an interest in the history of physics and the origin of the quantum world. In 1922 Bohr was awarded the Nobel Prize for his theory. The coming centenary will undoubtedly cause an increased interest in how he arrived at his revolutionary picture of the constitution of atoms and molecules.

IN a previous paper(On the constitution of atoms and molecules) the writer has shown that an explanation of some of the laws of line spectra may be obtained by applying Plancks theory of black radiation to Rutherfords theory of the structure of atoms. In the present paper these considerations will be further developed, and it will be shown that it seems possible on the theory to account for some of the characteristic features of the recent discovery by Stark[ of the effect of an electric field on spectral lines, as well as of the effect of a magnetic field first discovered by Zeeman. It will also be shown that the theory seems to offer an explanation of the appearance of ordinary double spectral lines

The probability that the most accurate method of determining the solar parallax now available is that resting on the measurement of the velocity of light, has led to the acceptance of the following paper as one of the series having in view the increase of our knowledge of the celestial motions. The researches described in it, having been made at the United States Naval Academy, though at private expense, were reported to the Honorable Secretary of the Navy, and referred by him to this Office. At the suggestion of the writer, the paper was reconstructed with a fuller general discussion of the processes, and with the omission of some of the details of individual experiments.To prevent a possible confusion of this determination of the velocity of light with another now in progress under official auspices, it may be stated that the credit and responsibility for the present paper rests with Master Michelson.Simon Newcomb,Professor, U.S. Navy,Superintendent Nautical Almanac.Nautical Almanac Office,Bureau of Navigation,Navy Department,Washington, February 20, 1880.

THE discovery. of the aberration of light was soon followed by an explanation according to the emission theory. The effect was attributed to a simple composition of the velocity of light with the velocity of the earth in its orbit. The difficulties in this apparently sufficient explanation were overlooked until after an explanation on the undulatory theory of light was proposed. This new explanation was at first almost as simple as the former. But it failed to account for the fact proved by experiment that the aberration was unchanged when observations were made with a telescope filled with water. For if the tangent of the angle of aberration is the ratio of the velocity of the earth to the velocity of light, then, since the latter velocity in water is three-fourths its velocity ill a vacuum, the aberration observed with a water telescope should be fourthirds of its true value.t * This research was carried out with the aid of the Bache Fund. t It may be noticed that most writers admit the sufficiency ot the explanation according to the emission theory of light; while in fact the difficulty is even greater than according to the undulatory theory. For on the emission theory the velocity of light !!lnst be greater in the water telescope, and therefore the angle of aberration should be less; hence, in order to reduce it to its Lrue value, we must make the absurd hypothesis that the motion of the water in the telescope carries the ray of light in the opposite direction

Lautore ha cercato negli anni un dizionario dei termini della viticultura nella Sicilia orientale senza mai trovarlo. Cosi e nata lidea di raccogliere quotidianamente questi termini dalla voce diretta dei protagonisti, annotati alla rinfusa nel corso del tempo. Il materiale e risultato infine generoso e quindi degno di una classificazione ben piu organica. Il testo raccoglie oggi oltre duecento parole della lingua siciliana, tutti termini specifici corredati da aneddoti e racconti delle vigne dellEtna. Si e cercato di conoscere ove possibile letimologia dei singoli termini e contestualizzarli con brevi appunti, momenti, eventi, discussioni, storie, cronache, dicerie ed altro ancora.Sono spesso memorie comuni, storie personali che raccontano anche eventi antichi.Attraverso la lettura di questo testo, dedicato alle vigne dellEtna, sara quindi possibile ancora una volta svelare la ricchezza linguistica e culturale di questa magnifica, emozionante, affascinante e contraddittoria terra.

Il Cosmo con un po di chaos. Lordine è larmonia sono chiamate a convivereCon un po di chaos e alcuni dicono che è meglio così. Il passaggio dal chaos al Cosmo non ha eliminato completamente

Tutto sommato, e probabile che in un prossimo futuro, il 2023 venga ricordato come lanno del contatto con la Macchinita. Nel mese di febbraio 2023, OpenAI ha lanciato la versione 4.0 di ChatGPT, un potente modello di intelligenza artificiale, ottenendo un notevole impatto emotivo sul pubblico. Con i suoi 180.000 miliardi di parametri schierati e funzionanti, ChatGPT4.0 ha fenomenologicamente impressionato anche gli addetti ai lavori. Gli effetti di tale impatto, incalzati dallarrivo di altri prodotti simili, sono destinati a persistere ed evolvere nel tempo. Ma non basta. Solo dieci anni prima, nel 2013, si comincio a parlare in sede industriale, ovvero fuori dei laboratori di ricerca, di possibili integrazioni del corpo umano con dispositivi elettronici o computer microscopici ( quanto e seccante portarsi lo smartphone in tasca) e ora, solo undici anni dopo, un cervello umano e stato dotato di una interfaccia cerebrale appena un pochino piu complessa del wireless del vostro mouse. Per altro i dishbrain, ovvero colture di neuroni umani o di topo su un disco di silicio, sono disponibili da tempo e, allegramente collegabili a un computer, imparano da soli e in pochi secondi a giocare a tennis. E tutto cio mentre linossidabile Facebook presidia, con investimenti da capogiro e impassibile alle relative cospicue perdite, il terreno del Metaverso. Anzi, ci crede cosi tanto che in un mondo dove sovente il marchio vale piu del prodotto, non ha esitato a modificare il suo brand in Meta. Che si attenda che tutti i suoi tre miliardi di utenti si colleghino senza piu essere costretti a smanettare smartphone oppure computer e tastiera? In realta, possiamo tranquillamente affermare che una profonda e totale trasformazione e appena iniziata, anzi a dir la verita, e semplicemente emersa in quanto era oramai impossibile nasconderla e lintelligenza artificiale, il metaverso, neuralink e dishbrain rappresentano solo le piu recenti e potenti espressioni di qualcosa che da molto tempo si e insinuato nel palcoscenico sociale umano: la Macchinita. La Macchinita, naturale contraltare dellUmanita, qualunque cosa sia e per definizione oggetto di indagine antropologica. Lantropologia studia luomo nelle sue varie manifestazioni culturali, sociali ed evolutive. Gli antropologi cercano di comprendere la diversita umana attraverso lanalisi di pratiche culturali, strutture sociali, credenze, valori e comportamenti umani. E tutti i sistemi sinora nominati con la loro silenziosa efficienza, la disarmante ingenuita, a volte lormai acquisita ubiquita, limplacabile potenza operativa ma soprattutto la dirompente capacita commerciale, modificano e modificheranno pesantemente il comportamento umano entrando obbligatoriamente anche nel mirino dellantropologo.Una volta pensavamo di essere al centro del mondo. Copernico ha mostrato che cosi non e.Una volta pensavamo di essere differenti e separati dal mondo animale. Darwin ha mostrato che cosi non e. Una volta pensavamo di essere padroni delle nostre decisioni. Freud ha mostrato che cosi non e. Una volta pensavamo di essere reali. Bohr ha mostrato che cosi non e. Da sempre pensiamo di essere intelligenti e consideriamo questa qualita come qualcosa di esclusivo. Come una scintilla di divino. E se scoprissimo che

No meio evangélico dito pentecostal , não apenas se houve falar, como muitos têm, também, experimentado alguns dons do Espírito Santo. O fato é que a grande maioria do povo evangélico toma como base

Simple à lire et destiné à tout le monde, ce livre est rédigé par Thierry Velu, spécialiste des interventions de secours en zone sismique et président fondateur du GSCF (Groupe de Secours Catastrophe

Além dos aspectos individuais, a saúde mental é também determinada pelos aspectos sociais, ambientais, econômicos e fisiologicamente. A saúde mental não é algo isolado, é também influenciada pelo amb

Francesco Saverio De Sanctis (1817-1883) e stato uno scrittore, saggista, critico letterario, Libero Muratore e politico del Regno dItalia. Considerato tra i maggiori critici e storici della letteratura italiana nel XIX secolo, successivamente alla proclamazione dellunita dItalia e stato Governatore della Provincia di Avellino, Deputato per diverse legislature e ha piu volte rivestito la carica di Ministro della Pubblica Istruzione.La sua Storia della Letteratura italiana e stata per oltre un secolo un imprescindibile punto di riferimento, anche a livello internazionale.La Scienza e la Vita, che oggi riproponiamo ai nostri lettori, e il testo del discorso inaugurale tenuto da De Sanctis nellUniversita di Napoli il 18 Novembre 1872.Il motto della scienza era un giorno la liberta contro il limite; oggi e la ristaurazione del limite nella liberta. Noi abbiamo distrutti o indeboliti tutti limiti al di fuori, e non li abbiamo ricreati dentro di noi. Nel furore della lotta li abbiamo odiati, disconosciuti, e perche al di fuori erano superstizione, oppressione; abbiamo ucciso dentro di noi anche il sentimento che li rigenera, e siamo rimasti nel vuoto. Quei limiti sono lo stimolo che sviluppa le forze organiche e creano la serieta e la moralita dalla vita, e ci toglie allegoismo animale, e ci rende capaci del sacrifizio e del dovere. La scienza altro non e se non ricostituzione de limiti nella coscienza, la riabilitazione di tutte le sfere della vita.