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Home , Amedeo Avogadro, Hugo Schiff, Luigi Galvani, Stanislao Cannizzaro

IN DURING LATE 18TH AND 19TH CENTURIES

, Ignazio Renato Bellobono, CSci, CChem FRSC, FRSC LASA, Department of , University of Milan.

e-mail address : i.bell obon o@ti scali.i t LASA, Dept.Dept. ofPhysics, Physics, University of Milan  The birth of Luigi Galvani, , and Luigi Valentino Brugnatelli

 From Chemistry to Radiochemistry The birth ofChemistr y and Periodic Table and

 Contributions to Organic Chemistry

LASA, Dept.Dept. ofPhysics, Physics, University of Milan  1737 At the Faculty of Medicine of the University, the first chair of Chemistry is establishedestablished,,andandassigned to Jacopo Bartolomeo BECCARI (1692-1766). He studied phosphorescence and the action of light on silver halides  1776 In some marshes of the Lago Maggiore, near AngeraAngera,, Alessandro VOLTA ((17451745--18271827),),hi gh school teacher of physics in Como, individuates a flammable , which he calls aria infiammabile. Methane is thus discovered. discovered. Two years laterlater,,heheis assigned, assigned,asasprofessor of experimental phihysicscs,,toto the UiUniversi ty of PiPavia

LASA, DDtept. of PhPhys icscs,, University of Milan  1778 In aletter a letter to Horace Bénédict de Saussure, aaSwissSwiss naturalist, VOLTA introduces, beneath that of electrical capacitycapacity, the fundamental concept of tensione elettrica (electrical, tension), exactly the name that elettricaCITCE recommended for the difference of in an . of potential potential  17901790--17911791 VOLTA anticipatesanticipates,,bybyabout 10 yearsyears,,thethe GAYGAY--LUSSACLUSSAC linear de ppyendency of gas volume on tem pp,erature, at constant pressurepressure,,andandafew a fewyears later ((17951795)) anticipatesanticipates,,byby about 6years 6 years,,thethe soso--calledcalled John ’s rules ((18011801))ononvapour pressure

LASA, Dept.Dept. ofPhysics, Physics, University of Milan  1790 Luigi GALVANI (1737 (1737——17981798),),a physiologist and anatomist, anatomist, while applying an electrical stimulus to a sectioned frog, observedobserved,,byby touching the crural nervesnerves,,thatthatconvulsive movements occurred along its limbs, and attributed this phenomenon to animal ,,asaswell as to a connection between electricityelectricityand life. VOLTA’s controversy on this point of view is well knownknown;;butbut finaaylly he recognised the ppoioneering vaaulue of Galv ani ‘s experimentsexperiments,,whenwhenhis successful studies on the connection between chemical energy and electricity lead to the discovery, discovery,aafewfewyears later ((17991799--18001800),), of the pila di . Phenomena ener occurring enerin this device to convertdi VoltaVoltachemical energyyintinto electrical energy have been also named galvanism ((galvanicgalvaniccells) cells)

LASA, Dept.Dept. ofPhysics, Physics, University of Milan  1792 Luigi Valentino BRUGNATELLI (1761 (1761--18181818),), professor at the since 1796, edits Annali di ChimicaChimica. Some years later ((startingstarting from 18001800),), by using V the pila. di Volta (electrochemical cell able to convert chemical energy into electrical energyenergy),),he studies the reverse phenomenon (electrolysis, that is use of electricity to produce chemicalschemicals))

 1799 VOLTA, coming back from Pavia to Como (because (because the UiUniversit yyoof PiPaviaawaswas suppressed by the AtiAustrian rulersrulers,,andandbonapartist professors were banishedbanished))waswas studying, around these years, what we now call VOLTA’s effect.

LASA, Dept.Dept. ofPhysics, Physics, University of Milan metals When putting into contact different metals, metals,duedueto different energy lllevelssoof the irrconcondtiduction bdbandss,,anane ltlectron flow takes placeplace.. In those timestimes,,anywayanyway,,thisthisquantum mechanical explanation was far from being reached. reached.TowardsTowards the end of 17991799,, howeverowever,,VOLTAVOLTA’’’s distinction between dry ,,forforwhich the VOLTA’s effect appliesapplies,,andand humid metltals,,wwhenen,, iiin the presence of condtiducting saltssororac id solutionssolutions,,aamoremore remarkable flow of electricity occurredoccurred,, was made clearr.. For the first time in the history of physics and chemistrychemistry,,conversionconversion of what we call chemical energy into electrical energy was clearly shownshown,,bybyadevice a device,,whichwhichVOLTA himself called pila (alternate and vertical piling up of two metals, put in mutual contact by an ionically conducting solution or medium). LASA, Dept.Dept. ofPhysics, Physics, University of Millan On March 20th, 1800, a communication was sent by VOLTA to Sir Joseph Banks, Banks,presidentpresident of the Royal Society, by which he announced to the scientific community the invention of his electromotive apparatus or artificial electric organ, as compared to the natural organs of some fishes. fishes.TheThecommunication apparatus,was published on Philosophical Transactions, with the title, On the electricity excited substancesexcitedof different by kinds. After the Marengo’s defeatby the of the Austrian Army ((JuneJune14th 14th the mere 1800), the first Consul Napoleonmere contactBonaparte reopened the University of Pavia, and reinstated contact of ,,bybyaspecific a specific decree, Alessandro VOLTA as professor ofofexperimental conducting physicsphysics,,andanddirector of the physics laboratorylaboratory..conducting

LASA, Dept.Dept. ofPhysics, Physics, University of Milan High esteem and honours attributed by Napoleon to Volta, during the visit paid by VOLT A and BRUGNATELLI, to present VOLTA’s discovery at the Institut de ((NovemberNovember 77thth1801) 1801)areare well known, known,andanddehistorically France documenteddocumented..VOLTAVOLTAwas designed as foreign memberFrance of the Institut and awarddded byytthe gold medldal,,witwith a lflife donationdonation,,asaswell as (in 18051805))byby the Légion d’ award. In 1809 heewaswas ddiesigned as sena tor,d’HonneurHonneur and one year later countcount,,ofofthe Regno d’Italia ,,createdcreated by Napoleon at his peak. d’Italia In 1816, 1816,thetheVOLTA’s Opera Omnia were published in Florenceorence.. In 1819, VOLTA retireOmnia d tooprpritivate life, and died in his country house of Camnago (now (nowa fraction of Como, name d, iiin his honouronour,, Camnago VVlt)olta) iiin MhMarch 55thth 18271827,,atatthe age of 82. 82.

LASA, Dept.Dept. ofPhysics, Physics, University of Milan In 18221822,,fivefiveyears before the death of VOLTA, Amedeo AVOGADRO and Vittor io MICHELOTTI set up iiin TiTurinnaa series of fundamental experimentsexperiments,,totodevelop the chilhemical theory o f pilail di VltVolta,,anand undtdiderstanding, iiin terms of chemical reactionsreactions,,thetheconversion of chemical into electrical energy, as well as the reverse process, which BRUGNATELLI had been pioneering in the early 19th century, that is the use of electrical energy, generated by VOLTA’s cells, cells,toto produce chemicalschemicals..

The loop was thus closed, closed,andandanew a new branch of ChemistryChemistry,, ELECTROCHEMISTRY,,waswas ready to tktakeeooff, iiin the name of VOLTA. VOLTA.

LASA, Dept.Dept. ofPhysics, Physics, University of Milan An epistemologicalconsideration: consideration:

Just one hundred years ((18991899--19001900))afterafter the date of VOLTA’s discovery of electrochemical cell, cell,ininaperiod a period dense of new discoveriesdiscoveries,,officially on December 1414th,th, 19001900,,atat 55pm,pm,in the Institute of ofT Berlin UniversityUniversity,,MaxMaxPLANC K presented aoflecture, lecture Physics, Zur Theorie des Gesetzes Physics , Gesetzes der in which PLANCK, for the first time in the history of der Energieverteilung physicsphysics,,introducedintroducedEnergieverteilung the quantum in ,,aasmallsmall energy quantityy,,asas a “flformal assumption”,,oof which probblbably not even himself realised, realised,atat that timetime,,thethe tremendous itimportanceance.. in NormalspektrumNormalspektrum

LASA, Dept.Dept. ofPhysics, Physics, University of Milan A revolution was beginning in physics. physics.OnlyOnlyafew a fewyears beforebefore,,PLANCKPLANCK did not firmly believe in atomic theorytheory,, whichwhich,,ononthe contrary, contrary,hadhadbeen the base of all the chemistry of the 1919ththcentury, century,andandwas strengthened by LdLudwig i BOLTZMANN, iiin hissstustudies on t heeseconsecond principle of thermodynamics. thermodynamics.

PLANCK, effectivel y, durin g the two or three years which preceded the turn of the centurycentury,,disapproved the statistical and probabilistic approach of BOLTZMANN towards the second principle, principle,andandwas strongly polemical towards the whole . theory.

LASA, DDtept. of PhPhys icscs,, University of Milan FortunatelyFortunately,, just during the studies on the energy distribution in the spectrumspectrum,,PLANCK recognised B his debt tdtowards BOLTZMANN,,proposeproposed toocacall BltBoltzmann’’’s constant the kkconstantconstant of his equation on energy dist rib uti onon,,wwhich was theesamesame as tha t of sttitiltatistical interpretation of the second principle by BotlzmannBotlzmann,,andand proposed in 1905 and 1906 the Nobel prize for the austrian . scientist.

LASA, DDtept. of PhPhys icscs,, University of Milan ButBut,,unfortunately, unfortunately,ititwas too latelate..BoltzmannBoltzmann,,feelingfeeling iltdisolated and unapprecitdiated, died iiin DiDuino, near TiTriest e, on September 1906, 1906,atatthe age of 62. 62.BoltzmannBoltzmannwas wrong iiin ddiiespising himself : heewaswas among theemosmost respected and admired physicists of the 1919ththcentury, century, and Planck, at the end, described his work as “one of the most beautiful triumphs of theoretical researchresearch””..

In factfact,,thethe atomic theory and what we now call the quantum theory were complementarycomplementary,,asasshown, shown,sincesince the beginningbeginning,,bybythe Kirchhoff’s Kirchhoff’s equation on energy dist rib uti onsons,, ititdinvestigated by Wien and afterwar ds by PlanckPlanck,,giving rise to the revolution of quantum physics and quantum c hithemistry through hout the 20th centuryury..

LASA, DDtept. of PhPhys icscs,, University of Milan  The birth ofElectrochemistry LiiGlLuigi Galvani iAl, Alessand ro V Vltolta, and Luigi Valentino Brugnatelli

 From Chemistry to Radiochemistry The birth of Chemistry and Periodic Table AdAAmedeo Avogad ro and dStil Stanislao CiCannizzaro

 Contributions to Organic Chemistr y LASA, DDtept. of PhPhys icscs,, University of Milan CHEMISTRY AND PERIODIC TABLE (1) About 40 years before the birth of RADIOCHEMISTRY, a great debate was taking course in CHEMISTRY, concerning the essence itself of this new-born science, from thequestion of atomicand molllecular weihights to periodical properties of the elements and their compounds. But, even about four decades before, Amedeo Avogadro, count of Quaregno and Cerreto, basing on thework by Joseph Gay-Lussac (1808) had published in the edition of JlJuly 14th 1811 on JlJournal dde Ph iysique, dde Chimie et d'Histoire naturelle his paper Essai d'une maniè ere de déte minerminer les relati esves des élémentaires des corps, et les proportions selon lesquelles elles entrent dans ces combinaisons. LASA, Dept.Dept. ofPhysics, Physics, University of Milan CHEMISTRY AND PERIODIC TABLE (2) The Avogadro’s hypothesis was founded on the diversity between and molecules, which himself was confusin g,,asaswell as on the possibility that elements could also be present in amolecular a molecularform. form. Each chemistry student toto--daydaylearns and experiments Avogadro’s law ;;butbut the scientific community of the early 19th century did not accept Avogadro’s principles, still when, three years later ((18141814),), André –Marie – Marie Ampère,,showedshowedtheir validity, even if by another experimental methodmethod..

LASA, Dept.Dept. ofPhysics, Physics, University of Milan CHEMISTRY AND PERIODIC TABLE (3) This hostility was primarily due to the fact thatthat,,byby exppgerimenting with inorganic substances , often these latter underwent dissociation, dissociation,thusthuscausing major discrepancies with respect to previsions of Avogadro’s principleprinciple..OnOnthe contrarycontrary,,whenwhen studies on or ganic substancessubstances,,isolatedisolated from natural products or synthetisedsynthetised,,became more frequentfrequent,, Avogradorado’s’sprinciple was checked again and found to be fully reliable to calculate molecular wei ghtshts.. The first to have envisaged the potentiality of Avogadro’s principle and its correctness has been aayounyoung researcherresearcher,, Stanislao CannizzaroCannizzaro,, born in ((JulyJuly13 th 18261826),),who won the chair of chemistry in 18551855,,atatthe University of Genoa. Genoa. LASA, DDtept. of PhPhys icscs,, University of Milan CHEMISTRY AND PERIODIC TABLE (4) In this Universit y, he published in 1858 Sunto di un Corso di FilosofiaFilosofia Chimica ,,ininwhich he gave the outmost value to Avogadro’s principle, by considering that if two , Chimica in the same temperature and pressure state, contain the same number of molecules, the ratio of their two volumes gives directly the ratio of their molecular (what we now call formula weights )).. For example, if 1L 1 Lofofhydro gen (a biatomicweights gas) at 00°°CC and 760 mm Hg pressure has the of 00..090090 g, and 11LLofof (an equally biatomic gas) in the same conditions has the weight of 11..4343 g, the oxygen should wei ghh11..4343 / 00..090090 times, that is 15. 15.99 times, that of hydrogen. hydrogen.

LASA, Dept.Dept. ofPhysics, Physics, University of Milan CHEMISTRY AND PERIODIC TABLE (5) Innoother terms, on are a reltilative scallle iiinnwwhich the hdhydrogen molecule has the value of 22..016016,,thethevalue of theC oxygen molllecule iiis 2.016 x 15.9, tha t iiis 32.0. This CiCannizzaro rule allowed to calculate, very reliably, atomic weights, as the Avogadro’s rule did for molecular weights. During the presentation of these principles by Cannizzaro, Cannizzaro, four years after Ad’Avogado’s dthdeath,,aat the first International Congress of Chemistry of Karlsrule, Karlsrule,inin 1860, where also Dmitrij Ivanovič Mendeléev and Julius Lothar Meyer were present, the latter addressed to Cannizzaro a well known appreciation (you gave us ))..Cannizzaro himself gave, at that Meetingus back,backthe ourfull explanation of the apparent deviations our sight from Avogadro’s sightprinciple, shown by molecules in a dissociation equilibrium.

LASA, Dept.Dept. ofPhysics, Physics, University of Milan CHEMISTRY AND PERIODIC TABLE (6) Four years after the Karlsruhe Conference, in 1864 , Lothar Meyer published the first attempt to correlate properties p T of 28 elements (periodic Table) with the concepttofof valence..OnlyOnlyin 1869, 1869,followingfollowing the possibility offered by the Avogadro’s and Cannizzaro’s criteria to evaluate correctly atomic masses of the elements, Mendeléev was able to fit in this Table all elements known at that time, and to foresee the existence of new elements in the voids of this Table (the ekaeka- ))..TheThe -elementselements confirmation, afew a few months later, by Lothar Meyer of the Mendeléev Table, and its substantial periodicity (some exceptions apar t) alllso as a ftifunction o f atitomiccweweihtight,,asas well as the discovery of some of the eka- eka-elements,elements, have been the first outttstan ding rationa lisati on o f Chemi st ry, to the birth of which Avogadro and Cannizzaro had given such an important quantitative contribution. LASA, Dept.Dept. ofPhysics, Physics, University of Milan CHEMISTRY AND PERIODIC TABLE (7) However, it has been RRdlfudolf Claus ius,,wwith his kineti c theory of gases ((18571857),), and Jacobus Henricus van’t HffHoff, byyappapplilying thermo dynami ccmemetdtods toosstdtudy solutions (1886 (1886),),and discovering the formal analogies with Avogadro’s and Cannizzaro’s criteria, to give final approval to Avogadro’s hypothesis and to considering this scientist as a founder of atomic - molecular theory. During these same years, aanewnewscience was rising, Thermodynamics, potentially able to give to other sciences powerful hints, as has done, among the first ones, to Chemistry. Thus, towards the end of the 19th century, Chemistry, and theeperperidiiodic TblTableeparparticul arl y, were conceptlltuallyyreaready to the discovery of Radioactivity and to the birth of

Radiochemistry. LASA, Dept.Dept. ofPhysics, Physics, University of Milan  The birth ofElectrochemistry Luigi Galvani, Alessandro Volta, and LiiVlLuigi Valenti no Brugnate lli

 From Chemistry to Radiochemistry The birth ofChemistry and Periodic Table Amedeo Avogadro and Stanislao Cannizzaro

 Contributions to

LASA, Deptt.. of Physicssics,, Organic Chemistry University of Milan c The term of organiiic chithemistry was adtddopted for the first time in 1806 by Joens Jacob BERZELIUS, due to the fact tha t this bhbranch of chithemistry was itintend dded toosstdtudy compounds extracted from living organisms, vegetals or animals, and/or their metabolites. Only in 1828, 1828,thethe German chemist Friedrich WOEHLER synthes ized urea from iiinorganic itinterme ditdiates, and showed that the synthetic molecule had the same properties as that isolated from animal organisms. In 1861 Auguste KE’KULE’ defined organic chemistry as “theesstdtudyyoof carbon compoun d”ds” ((ithwith miiinor exceptions, such as simple derivatives of carbon oxides). oxides).

LASA, Dept.Dept. ofPhysics, Physics, University of Milan Even if italian chemists, during the 19th century,p were predominantly what we would now name physical chemists or ,,suchsuch as AVOGADRO and VOLTAor,,w chemicalwihith a bkbackground fiformation iiinnpphihysics, as was knownc at chemical that time, physicists, some of them had interests in organiiic chithemistry, such asphysicists,CANNIZZARO,,ororwere mailinly devoted to organic chemistry as such. such.

AAbriefbrief historical outline, for the most important contributors to organic chemistry as such, will be presented in the following slides. slides.

LASA, Dept.Dept. ofPhysics, Physics, University of Milan In 18381838,,Raffaele PIRIA (1814 (1814--18651865),), while studying chemistry with Dumas in , carries out important researches on salycin and on composition of glucosides. glucosides. His researches are published on Comptes Rendus de l’Académie des and Annales de Physique. de Chimie des Sciences, Chimie et AAfewfewyears later Sciences, ((18441844--18461846),),while studying asparaginin et de and aspartic acid, he sets up the reaction which still de carries his name (Piria (Piria reaction between aliphatic amines and nitrous acid to yield the corresponding alcohols)alcohols).. At the University of , he founded the chemical laboratory, which soon became a reference point for chemistry students in Italy (CANNIZZARO has been PIRIA’s student in this University, before PIRI A moved to the University of ). Turin).

LASA, Dept.Dept. ofPhysics, Physics, University of Milan In 18471847,,AscanioAscanio SOBRERO (1812 (1812--18881888),), at the , Turin,producesproduces,,forforthe first timetime,,nitroglycerolnitroglycerol..HisHis researches will constitute the basis of the further studies on this field by Alfred NobelNobel..

In 1853, Stanislao CANNIZZARO, who, at that time was teaching chemistry at the National College of Alessandira (near Turin), discovered the dismutation of aldeh ydes, a reactionreaction,,whichwhich still carries his name. name.TwoTwo years laterlater,,hehe was appointed professor at the University of Genoa. Genoa.

LASA, Dept.Dept. ofPhysics, Physics, University of Milan In 18641864,,HugoHugo SCHIFF ((18341834--19151915),),at that time professor of chemistry at the Museum of Physics and Natural Sciences in FlorenceFlorence,,discoversdiscovers the condensation reaction of aldehydes with amines (aromatic amines particularlyparticularly),),yielding productsproducts,,whichwhich are still named SCHIFF bases.

In 1878, Francesco SELMI (1817-1881), professor of chemistry at the , studies the toxicologic importance of some alcaloids, a few years after the foundation of Gazzetta Chimica ((18711871),), the official organ of italian chemistsChimica italiana italiana

LASA, Dept.Dept. ofPhysics, Physics, University of Milan In 18811881,,GiacomoGiacomoLuigi CIAMICIAN (1857 (1857--19221922),), at that time associated to the CANNIZZARO’s group in Rome, before becoming professor of chemistry, chemistry,firstfirst at the University of Padova (1887) and afterwards at Bologna ((18891889),), begins his fundamental studies on pyrrole chemistry, and transformation of five atoms heteroaromatic rings into six atoms rings, rings,like pyridine. pyridine.

In 18961896,,AngeloAngeloANGELI ((18641864--19311931),), graduated in 1891 at the Unive rsit y of Bologna in the CIAMICIAN’s gogroup , discovers nitro, hydroxylamino acid. acid.InIn 1915 he will be appointed professor of organic chemistry in . His name is tied to the Angeli reaction for aldehydes detection, and to the Angelo-Rimini reaction between aldehydes and N- N-hydroxybenzenehydroxybenzene sulphonamidessulphonamides..

LASA, DDtept. of PhPhys icscs,, University of Milan SOME CONCLUDING EPISTEMOLOGICAL CONSIDERATIONS

Not always (on the contrarycontrary,,rarelyrarely),),in the , really innovating or revolutionary ideas are rapidly accepted by the scientific community, or soon become the common herita gee..

Moreover, sometimes, even who fosters the innovations is not fully aware of their importanceimportance,,andandcannot be, be,sincesince developments often go beyond the starting ideas and concepts

LASA, DDtept. of PhPhys icscs,, University of Milan Two excellent and leading examples of this assertion have been the atomic theory in the 19th century and the quantum theory in the 2020th,th, both of which, which,startingstarting from physical theories, had an enormous impact on ChemistryChemistry..

WhenWhen,,inin1900, 1900,PlanckPlanckintroduced the quantum conceptconcept,,hehe did not reallyymeanmean tha t energyycoucould beeconsconsidered as discreet bulletsbullets,,butbutthat its way of exchange into heat was schsuch,,wwithout vaingarying its natur e,,wwhich Planck fir mly held as undulatory, undulatory,andandonly like so. so.

It has been only five years laterlater,,ininq 1905, 1905,thatthat Albert EINSTEIN explicitly considered the quantum of light,,asas the smallest energy quantity that one could consider. consider. LASA, DDtept. of PhPhys icscs,, University of Milan Only by this way, the photoelectric effect could be explained and quantitatively interpreted, and, for the first timetime,,thethe Planck h effectexperimentally evaluated. hconstant constant L B AAdnd it has been onllly iiin 1923 tha t LiLouis dde BliBroglie realised that EINSTEIN’s discovery of 1905 ( the dual dual nature energy, both corpuscular and wave-like) couldnature ofbe generalised and extended to all material particles, particlesof, particularly to electrons.

LASA, DDtept. of PhPhys icscs,, University of Milan The pathsof Science are not straight and easy.

In the 1717thth century, the same occurred to the founder of Science in the modern sense, sense,Galileo GALILEI, and later to Isaac NEWTONNEWTON..

Newton was born in 1642, the same year in which Galilei dieddied..EinsteinEinstein was born in 1879, 1879,thethe same year in which Maxwell died. Some kind of torch-bearers, in the language of olympic gamesgames..

LetLet’s’s all be torchtorch--bearersbearers of Science, no matter how difficult and wearisome this task may be.

LASA, DDtept. of PhPhys icscs,, University of Milan In 19271927,,justjust85 years ago, the International Congress of Physics was held in Como, from September 11th to September 2020th,th,to commemorate the hundredth Anniversary of Volta’s death.

On September 16t 16th,,BoBohr presented for the first timetime,,toto the scientific audience, the idea of complementarity such as giii ven by HHieisenb erg’’’ssprpriilincipleeoof idtindetermi nati onon,, linked to the role of measurement in quantum theorytheory,, and the probabilistic inter pr etation given by Bor n to the Schroedinger wave functionfunction,,toto constitute the foundation for a new conception of quantum mechanics. This fusion of ideas will soon be named Copenhagen interpretation of quantum theory. interpretation

LASA, DDtept. of PhPhys icscs,, University of Milan Among the audience, at the Istituto Carducci, where the meeting was held, Born, de Carducci,Broglie, Compton, HeisenbergHeisenberg,,Lorentz, Lorentz,PauliPauli,,PlanckPlanck,,andand Sommerfeld were present.

Two physicists were absent at theeComoComo’’’s meeting of September 1927. 1927.Schroedinger had moved, moved,onlyonly some weekssearearlierer,, to BliBerlinn,,wwhere heewaswas called as Planck ’’’s successor, and was consequently involved in urgent home-setting. Einstein refu sed to tou ch the then fascist ItalyItaly..BohrBohrwould have met him only one month later in Brussels at the famous Solvay meeting, the fifth of the seriesseries..TheirTheircontroversy on the Copenhagen interpretation will continue.

LASA, DDtept. of PhPhys icscs,, University of Milan  The paths of Science are not straight and easy.

 Let’s all be, humbly but proudly, torch-bearers of Science, no matter how difficult and wearisome this task may be. LASA, Dept.Dept. ofPhysics, Physics, University of Milan f f o o p ty o i LASA, Grou at LASA, vers i ,at n UiU i the Grou , cs cs, i and the , ys Committee, Ph i f o Bonardi , cs cs, i s Organising Committee PhPhy i Mauro Bonardi f Milan o . o t of Milan ACKNOWLEDGEMENTS . .Mauro ep f epartment o Dt D D , the Organising D Milan Pro University of LASA