Ingeniørens kvanteskole del 1: Elektroner har spin

"Det stod nu klart, at naturen på den mindste skala opførte sig helt anderledes end på stor skala"

I vores solsystem kredser de yderste planeter selvfølgelig langsommere om solen end de inderste. I Mælkevejen kredser de yderste solsystemer imidlertid lige så hurtigt om centrum som de inderste. Deraf udledes den mørke masse.

Også på den største skala opfører naturen sig helt anderledes end på stor skala.

I øvrigt tak for en god lektion:-)

Hvad er egentlig en god visualisering af elektroner? At de er lidt ligesom skyer der er flere steder på én gang og kan interferere med sig selv og samtidig samle sig til et punkt hvis de interagerer med andre partikler? Eller hvad?

I Mælkevejen kredser de yderste solsystemer imidlertid lige så hurtigt om centrum som de inderste.

Måske man burde betragte en galakse som et stillestående objekt hvor universet roterer om. Alt er jo relativt med betragteren.

Måske man burde betragte en galakse som et stillestående objekt hvor universet roterer om

Jeg er bange for at det giver et problem for betragtningen af de andre galakser...

Hvad er egentlig en god visualisering af elektroner? At de er lidt ligesom skyer der er flere steder på én gang og kan interferere med sig selv og samtidig samle sig til et punkt hvis de interagerer med andre partikler? Eller hvad?

Hej Ole

Her har du svar i flere kontekst - det du "ser" er interaktionen med elektronen (kilde):

25. maj 2011, ing.dk: Overraskelse for forskere: Elektroner er kuglerunde

University of Groningen (2013, August 29). Why electrons pass through very tiny wires less smoothly than expected: Light shed on 20-year-old mystery. ScienceDaily: Citat: "...Electrons that flow through the wire behave like quantum waves. 'They bash against the walls, and sometimes reflect from the flanks of the mountain pass. They also sense each other's presence.' This results in a complex interaction of various physical phenomena. 'We call this "many body physics." It is very complex..."

27. feb 2008, Ing.dk: Video: Verdens første billede af en elektron: Citat: "...Filmen er i virkeligheden elektronens energifordeling gennem et kort stykke tid, og altså ikke en rigtig filmoptagelse i gængs forstand..."

Elektronens "form" afhænger af hvilken elektronskal den er i. Se linkens sides bileder i højre side.

May. 24, 2013, sciencemag.org: A Snapshot of the Inside of an Atom: Citat: "... Physicists have, for the first time, been able to image the quantum workings of electrons in hydrogen atoms, an advance that could open the door to a deeper understanding of the quantum world. ..."

Max-Planck-Gesellschaft. (2010, July 1). Electrons are late starters: Contrary to previous assumptions, electrons are catapulted out of an atom during photoemission with a delay. ScienceDaily: Citat: "... Accordingly, it takes a few tens of attoseconds before an electron flies out of the atom. Although this is only a few billionths of a billionth of a second, even this fleeting moment is sufficient to rattle the theory that physicists have put forward about what happens electronically in the atom. "Our findings provide further important insight into the interactions of electrons in atoms," says Ferenc Krausz, in whose department at the Max Planck Institute of Quantum Optics the experiments were conducted. ..."

Elektronens bølgefunktion kan ændres:

January 21, 2015, scitechdaily.com: A Way To Self-Propel Subatomic Particles Without External Forces: "... Some physical principles have been considered immutable since the time of Isaac Newton: Light always travels in straight lines. No physical object can change its speed unless some outside force acts on it. ... Now, in a new variation on the methods used to bend light, physicists at MIT and Israel’s Technion have found that subatomic particles can be induced to speed up all by themselves, almost to the speed of light, without the application of any external forces. ... The new findings are based on a novel set of solutions for a set of basic quantum-physics principles called the Dirac equations; these describe the relativistic behavior of fundamental particles, such as electrons, in terms of a wave structure. (In quantum mechanics, waves and particles are considered to be two aspects of the same physical phenomena). By manipulating the wave structure, the team found, it should be possible to cause electrons to behave in unusual and counterintuitive ways. ... It turns out that this self-acceleration does not actually violate any physical laws — such as the conservation of momentum — because at the same time the particle is accelerating, it is also spreading out spatially in the opposite direction. [] “The electron’s wave packet is not just accelerating, it’s also expanding,” Kaminer says, “so there is some part of it that compensates. It’s referred to as the tail of the wave packet, and it will go backward, so the total momentum will be conserved. There is another part of the wave packet that is paying the price for the main part’s acceleration.” It turns out, according to further analysis, that this self-acceleration produces effects that are associated with relativity theory: It is a variation on the dilation of time and contraction of space, effects predicted by Albert Einstein to take place when objects move close to the speed of light. An example of this is Einstein’s famous twin paradox, in which a twin who travels at high speed in a rocket ages more slowly than another twin who remains on Earth. ..."

October 29, 2014, scitechdaily.com: New Research Suggests Electron Wave Function Can Be Split and Trapped: "... Experiments led by Humphrey Maris, professor of physics at Brown, suggest that the quantum state of an electron — the electron’s wave function — can be shattered into pieces and those pieces can be trapped in tiny bubbles of liquid helium. To be clear, the researchers are not saying that the electron can be broken apart. Electrons are elementary particles, indivisible and unbreakable. But what the researchers are saying is in some ways more bizarre. ... “The experiments we have performed indicate that the mere interaction of an electron with some larger physical system, such as a bath of liquid helium, does not constitute a measurement,” Maris said. “The question then is: What does?” And the fact that the wave function can be split into two or more bubbles is strange as well. If a detector finds the electron in one bubble, what happens to the other bubble? “It really raises all kinds of interesting questions,” Maris said. ... Scientists have wondered for years about the strange behavior of electrons in liquid helium cooled to near absolute zero. When an electron enters the liquid, it repels surrounding helium atoms, forming a bubble in the liquid about 3.6 nanometers across. The size of the bubble is determined by the pressure of the electron pushing against the surface tension of the helium. The strangeness, however, arises in experiments dating back to the 1960s looking at how the bubbles move. ... Experiments have detected unidentified objects that reach the detector before the normal electron bubbles. Over the years, scientists have cataloged 14 distinct objects of different sizes, all of which seem to move faster than an electron bubble would be expected to move. “They’ve been a mystery ever since they were first detected,” Maris said. “Nobody has a good explanation.” ... They were able to detect all 14 of the objects from previous work, plus four additional objects that appeared frequently over the course of the experiments. But in addition to those 18 objects that showed up frequently, the study revealed countless additional objects that appeared more rarely. ... “That puts a dagger in the idea that these are impurities or helium ions,” Maris said. “It would be hard to imagine that there would be that many impurities, or that many previously unknown helium ions.” [] The only way the researchers can think of to explain the results is through “fission” of the wave function. In certain situations, the researchers surmise, electron wave functions break apart upon entering the liquid, and pieces of the wave function are caught in separate bubbles. Because the bubbles contain less than the full wave function, they’re smaller than normal electron bubbles and therefore move faster. ..."

4. aug 2009, ing.dk: Cambridge-forskere: Nu kan vi få elektroner til at dele sig: Citat: "...De to nye partikler kaldes spinons og holons..."

Jul 27, 2011, physicsworld.com: Spinons take the heat: Citat: "... An international group of researchers has measured, for the first time, the phenomenon of spin–charge separation in bulk in a solid. They also found that the material violates the empirical Wiedemann–Franz law that has held true for more than 150 years. ... The dramatic departure from the Wiedemann–Franz law occurs in purple bronze because when a holon comes across an impurity in the chain of atoms its motion is reflected – that is, it cannot navigate around or through the impurity. But the spinon can tunnel through the impurity and then continue along the chain. Because the spinons carry heat and the holons carry charge, the heat is conducted easily along the chain but charge is not. ..."

April 19, 2012, scitechdaily.com: Splitting of an Electron into the Spinon and Orbiton: Citat: "... An electron has been observed to decay into two separate parts, each carrying a particular property of the electron: a spinon carrying its spin – the property making the electron behave as a tiny compass needle – and an orbiton carrying its orbital moment – which arises from the electron’s motion around the nucleus. ..."

Princeton University (2012, June 13). Got mass? Scientists observe electrons become both heavy and speedy. ScienceDaily: "... Making this groundbreaking observation of electrons as they transition from light to heavy particles is only part of the story. The researchers also showed how the process can be understood based on quantum theories of electron behavior. Subatomic particles such as electrons can exhibit strange behavior because of quantum entanglement, which can mix diametrically opposite behaviors together. By comparing the data with theoretical calculations, the study shows that heavy electrons emerge from entanglement of two opposite behaviors of electrons, one in which they are localized around individual atoms and the other in which they are hopping freely from atom to atom in the crystal. "This is the first time we have a precise picture of formation of heavy electrons, thanks to our ability to probe them with high resolution," Yazdani said. ..."

Først tak for en utrolig fin fremstilling, og for din hidtidige tålmodighed hvad angår nedenstående.

"Det var Albert Einstein, der i 1905 tillagde virkningskvantet en reel fysisk egenskab og forklarede, at lyset energimæssigt altid bestod af pakker med en energi, som var frekvensen gange Plancks konstant.” Desuden formulerede Einstein Relativitetsteorierne hvor tilføjelsen af en ekstra dimension – tiden var en uomgængelig forudsætning.

Lad det være sagt med det samme, at såvel Einstein som Schrødinger eller Bohn aldrig accepterede kvantemekanikken som andet end en midlertidig teori som muliggjorde at man kunne komme videre med den praktiske udforskning af de registrerede fænomener.

Det er allerede med dobbelt spalte problematikken at kvantemekanikkens erkendelsesmæssige vej skiller sig fra den klassiske fysik. Det unikke ved den klassiske fysik er jo at man ud fra entydige begreber kan forudsige den videre udvikling.

Indenfor naturvidenskaberne har der også tidligere været uforenelige fænomener. Sådanne uforenelige fænomener har så ledt til konkurrerende ”skoler”, hvor den ene var egnet til bedst at tolke nogle af videnskabens områder, og den anden var bedst til andre. I tidligere tilfælde er sådanne uoverensstemmelser blevet forenet gennem videreudviklingen af den pågældende videnskab. Det særlige ved den kvantemekaniske teori er, at den på trods af åbenlyse brister har tilkæmpet sig total dominans, nok fordi de fleste tænker ”når resultaterne er brugbare er teorien nok det nærmeste man kan komme på den underlige subatomare virkelighed”!

Billedligt stod fysikerne, med dobbeltspalte problematikken, i den situation, at de indenfor synsfeltet havde et nyt for dem ret fremmed og derfor næsten usynligt fænomen ”multidimensionalitet” - Einstein havde jo lige indført en ekstra dimension. De var imidlertid alle, også Einstein, oplært i de klassiske dimensioners verdensbillede, så de holdt sig til de begreber de allerede var vant til at arbejde med, og hævdede, at verden på kvanteniveauet ikke bare så mystisk ud men reelt var mystisk!

Det var som at bevæge sig ind i en ukendt skov (men dog en skov – et fænomen man kendte) hvor man for at orientere sig ikke kan klare sig med sine 10% bevidste lineære hjernefunktioner, men hele tiden må forklare det nye man ser ved hjælp af sine 90% underbevidste parallelt processerende kreative hjernefunktioner. Man må så at sige føle og gætte sig frem gennem den ukendte skov fra træ til træ!

De fleste der bevæger sig ind i en ukendt skov kommer ud igen, netop fordi de har en kreativ, nærmest genial underbevidst hjerne, men det er trods alt umådelig imponerende hvor langt kvantevidenskaben er kommet ved hjælp af den metode.

Forståelse og accept af begreber er noget der sker inde i hovedet på mennesker der tolker fysiske fænomener. Forståelsen er altså noget andet end den registrerede fysik.

Ud fra resultatet af dobbeltspalte eksperimentet accepterede man forståelsesmæssigt at verden var spaltet i en makro fænomenologi og en hidtil uforenelig kvante verden fænomenologi der var så mystisk at den stedse forklaringsmæssigt måtte korrigeres, og selv om disse korrektioner gjorde det muligt at komme videre med forskningen, afstedkom korrektionerne også stedse mere komplicerede og snørklede beskrivelser af de registrerede sub-atomare fænomener.

Den indlysende (og tør jeg sige med Einstein, Schrødingers og Bohns skepsis i ryggen) klassiske fysiske vej ud af denne forvirrende og mystiske situation vil være, at konkludere at dobeltspalte problematikken synliggør en dualitet der kan forventes opløst gennem indførelse af en 5 dimension, indenfor hvilken de to fænomener partikler og lys fremstår som det højere enkeltfænomen det nok i virkeligheden drejer sig om.

" A thought experiment - a straight forward understanding of the quantum phenomena.

Our three dimensional reality may be compared with a room. A room which by us is experienced as completely closed . This room has in reality openings into other rooms, into other dimensions, but we who are inside the room have no knowledge of those openings, let alone of the other rooms. Even though we are not aware of the openings into other rooms (other dimensions), we who are inside this three-dimensional room can nevertheless register the fact that things suddenly turn up in the room that were not previously present, and also that things that have been registered there suddenly vanish. We can furthermore calculate the statistical probabilities for things turning up or vanishing, and we can also register "non locality", i.e. that certain of our actions are linked ”non-causally” with other events in the room! Imagine a ball or something else in the room being hit and consequently jump out of one of the unknown openings in the room (out of our three-dimensional reality). Outside our room it interacts with something and as a consequence of this interaction it influences something else in our room (by way of another opening) and that phenomenon will by us be perceived as “non-locality”! Such a causal explanation (incorporating hitherto unknown real dimensions) would explain vanishing particles as well as the spontaneous creation of particles and also explain the phenomenon’s of “non locality” and “entanglement”! Although seemingly mystical and incomprehensible, all this becomes uncomplicated and easy to grasp as soon as we recognise the existence of openings leading into other rooms , and that the reality of our own three-dimensional room is bound up with and dependent on the existence of other rooms in the house! The existence of other real dimensions. Within the social sciences like phenomenon´s are recognized as "meaningful coincidences"!" Fra “Science History and the Future” http://unifiedscience.blogspot.com/2011/02...

Det er som sagt vildt imponerende hvor langt man med den nuværende ”Standard model” forståelse er kommet, og at den praktiske udnyttelse indenfor feltet er klar til at ”kvantespringe” fremad, men det er min påstand, at den pågældende udvikling ville blive markant effektiviseret og meget billigere, såfremt man formåede at formulere fænomenologien klassisk fysisk ud fra en reel multidimensionalitet. Formuleringen af en sådan klassisk videnskabelig partikel fysisk teori vil være den sikre vej til en hurtig Nobelpris, således at den pågældende geniale forsker/forskere slipper for at gå og håbe og vente indtil langt ind i pensionsalderen!

Går vi tilbage til Tycho Brahes tid resulterede den daværende geocentriske forståelse af kosmos også i at de observerede planetbevægelser fremstod tilsvarende krøllede og mærkelige. Alt det krøllede blev som bekendt ligefremt, logisk og forudsigeligt da Kopernikus brugte Tycho Brahes hidtil uovertrufne observationer til en heliocentrisk beskrivelse af solsystemets bevægelser!

PLEASE stop de lange indlæg med mange eksterne links.. Tror ikke nogen orker dem længere - Kunne du ikke sammensætte et argument selv samt henvise til eventuelle links til sidst?

PLEASE stop de lange indlæg med mange eksterne links.. Tror ikke nogen orker dem længere - Kunne du ikke sammensætte et argument selv samt henvise til eventuelle links til sidst?

Hej Allan

Jeg forsøgte at finde så mange "direkte målinger" af elektronen/ kvantemekanisk-elektronbølgefunktionen i forskellige sammenhænge. De er det mest "nøgne" syn af elektronen jeg kunne give/finde. Jeg kan ikke diske op med et par simple matematiske modeller af en kvantemekanisk-elektronbølgefunktionen, så alle kan forstå det. Iøvrigt var det visualiseringer, som blev efterlyst - og det var det jeg gav.

Den kvantemekaniske-elektronbølgefunktions form er afhængig af måleopstillingen - incl. om elektronen laver en stående bølge om en atomkerne (atomkernen er også selv er en bølgefunktion). Nogle "elektronbaner" - rigtigere stående elektronbølgefunktioner - er ligesom ottetaller gennem atomkernebølgefunktionen.

Forskerne kan pt ikke give en måle(kontekst)uafhængig "udseende" af elektronen/elektronbølgefunktionen.

Så vi må tage til takke med de små portioner kvantemekaniske brødkrummer, naturen lader os få.

Fysikere har pt end ikke kunnet give en beskrivelse, som giver os en fælles forståelse af, hvad en kvantemekanisk måling er.

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Kilder:

Wikipedia: Kvantemekanisk måling: Citat: "... Kvantemekanik forudsætter en omhyggelig definition af kvantemekanisk måling. Kvantemekanisk måling problemstillingen ligger til grund for kvantemekanikfortolkninger - og der er i dag (2015) ikke konsensus om det. ... Kvantemekanisk måling er karakteriseret af, at der ved en måling sker der en kvantemekanisk sammenfiltring mellem partiklen [dens bølgefunktion] og måleapparaturet, der efterlades "noget", et aftryk, i apparaturet. Der var og stadig er til diskussion om hvad der egentligt sker, når man måler kvantemekanisk. Bølgen kollapser tilsyneladende pludseligt og der sker en dekohærens forårsaget af måleapparaturet. ..."

June 12, 2014, scitechdaily.com: Researchers Discover “Magic” Ingredient for Quantum Computing: Citat: "... Contextuality ... In quantum, the property you discover through a measurement, is not simply a property that the system actually had prior to the measurement process. What you observe necessarily depends on how you carried out the observation – it depends on the “context” of the experiment. ..."

May 15, 2012, scitechdaily.com: Quantum Theorists State That Wavefunctions Are Real, States Not Just Statistical Tools: Citat: "... The mathematics behind the claims of a group of quantum theorists state that the wavefunctions, a probability amplitude used to in quantum mechanics to describe a particle’s state, isn’t just a statistical tool but rather a real, objective state of a quantum system. The researchers published their findings in the journal Nature Physics. ... If wavefunctions simply reflect the experimenter’s uncertainty, then different wavefunctions could represent the same underlying reality. [] The authors show that the same reality cannot underpin different quantum states. The theorem depends on a controversial assumption, that quantum systems have an objective underlying physical state. ..."

Jun 15, 2011, physicsworld.com: Catching sight of the elusive wavefunction: Citat: "... "Our understanding of the wavefunction is rather abstract and there is no official textbook definition," says Lundeen. ..."

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Måling af en mikrobølgefotons tilstedeværelse (eller ej):

Centre National De La Recherche Scientifique (2007, April 2). Life And Death Of A Photon 'Filmed' For The First Time. ScienceDaily: Citat: "... A photon [også en kvantemekanisk bølgefunktion!] is an elementary particle of light. In general it can only be observed when it disappears ... The end result is that the atom changes to state 1 if the cavity contains a photon and remains at state 0 if it is empty, as in the standard method. However, this time the energy absorbed by the atom is taken from the auxiliary field and not from that of the cavity. As a result, the photon is still there after having been seen, and is ready to be measured again ... Suddenly the atoms appear in state 1, showing that a photon has been trapped between the mirrors. The photon comes from the residual thermal radiation which surrounds the cavity ... The moments at which the photons appear and disappear reveal the quantum jumps of light, which occur at random ..."

Jeg har det svært med disse fotoner. Sender du lys igennem en attenuator, kommer kun en del af lyset ud på den anden side. Hvis man tror at det indstrømmende lys er fotoner, bliver kun en del af fotonerne transmitteret, svarende til dæmpningen. Mit problem er så, hvordan overhovedet nogle fotoner kan komme igennem. De skal jo have samme energi som da de kom ind i attenuatoren, og da de er en eller anden bølgepakke, må de vel dæmpes også hver for sig. Henter de energi fra nogle af dem som bliver til varme, således at de alligevel kan slippe igennem? Man kunne jo mindske styrken af lyset, så kun en foton af gangen var i attenuatoren.

"Lad det være sagt med det samme, at såvel Einstein som Schrødinger eller Bohn aldrig accepterede kvantemekanikken som andet end en midlertidig teori som muliggjorde at man kunne komme videre med den praktiske udforskning af de registrerede fænomener."

Det er ikke rigtigt - Niels Bohr var den første til at se, at kvantemekanikken virkelig var fundamental anderledes end den klassiske fysik og at vi her har en indikation af, at fysikken, i sit væsen, er anderledes end vi ser den fra vores verden og end vi "troede den var"

Det er jo netop det, som hele Bohr - Einstein - diskussionen går ud på - nemlig, at Niels Bohr forsøgte at fortælle Albert Einstein om fysikkens sande væsen.

Her et udpluk på dansk:

• Bohr vs. Einstein: Fortolkning af kvantemekanikken Af Christian Kraglund Andersen og Andrew C.J. Wade, Institut for Fysik og Astronomi, Aarhus Universitet

Niels Bohr kunne dog godt lide denne fortolkning af kvantemekanikken og mente, at bølgefunktionen var en fin beskrivelse af kvantemekaniske fænomener. Må- linger derimod skulle beskrives ved hjælp af klassiske begreber som bølger og partikler, og i en enkelt måling ville man ikke kunne se både bølge- og partikelopførsel. I 1927 skrev Bohr bl.a. følgende til Einstein3: ... Denne vigtige pointe medfører, at det er umuligt at skelne skarpt mellem atomare objekter og deres vekselvirkning med et instrument, der søger at definere de betin- gelser, hvorunder fænomenet finder sted. Konsekvensen heraf er, at målinger opnået under forskellige betingelser ikke kan for- stås inden for et enkelt forsøg, men skal betragtes komplementært i den forstand, at kun summen af hele fænomenet giver den mulige information af objektet. Bohrs idé var med andre ord, at ville man opnå den fulde information om f.eks. en elektron4, så skulle man gennemføre komplementære, det vil sige indbyrdes forskellige og hinanden udelukkende, forsøg. Derfor er et lyskvant en partikel, når vi laver et eksperiment, der kigger på den som en partikel, og en bølge, når vi laver eksperimenter, der måler på den som en bølge. -

Og her citat af Niels Bohr - fra David Faverholdt - Filosoffen Niels Bohr side 125 - Atom teori og Naturbeskrivelse side 15

"Komplementaritet - Som nævnt talte Niels Bohr om komplementaritet i forbindelse med kvantemekanikken - "

""er egnet til at omfatte kvantefænomenernes karakteristiske individualitet og samtidig klarlægge de særegne træk, som iagtagelsesproblemet på dette erfaringsområde udviser.""

""selve grundpostulatat om virkningskvantets udelelighed ... henviser os til en beskrivelsesmåde, der betegnes som komplementær i den forstand, at enhver given anvendelse af klassiske begreber udelukker den samtidige benyttelse af andre klassiske begreber, der i anden sammenhæng er lige så nødvendige for fænomenernes belysning.""

Mit problem er så, hvordan overhovedet nogle fotoner kan komme igennem

Som jeg har forstået det, har hver enkelt foton en given sandsynlighed for at slippe igennem. Hvis din attenuator dæmper lyset med f.x. 50 %, betyder det at hver anden foton i gennemsnit slipper igennem.

Jeg har det svært med disse fotoner. Sender du lys igennem en attenuator, kommer kun en del af lyset ud på den anden side. Hvis man tror at det indstrømmende lys er fotoner, bliver kun en del af fotonerne transmitteret, svarende til dæmpningen. Mit problem er så, hvordan overhovedet nogle fotoner kan komme igennem. De skal jo have samme energi som da de kom ind i attenuatoren, og da de er en eller anden bølgepakke, må de vel dæmpes også hver for sig. Henter de energi fra nogle af dem som bliver til varme, således at de alligevel kan slippe igennem? Man kunne jo mindske styrken af lyset, så kun en foton af gangen var i attenuatoren.

Hej Svend

Hvis du synes ovenstående er mærkeligt, så se og læs om følgende eksperiment:

Nov 26, 2013, physicsworld.com: Physicists ask photons 'Where have you been?': Citat: "... A new version of the famous double-slit experiment has allowed physicists in Israel to measure a phenomenon that is bizarre even by the counterintuitive standards of quantum mechanics. By placing a double-slit experiment along one path of a larger double-slit experiment, the researchers have shown that photons traverse a section of the apparatus that they neither enter nor exit. ..."

Hvis du synes ovenstående er mærkeligt, så se og læs om følgende eksperiment:

Det er ikke helt klart hvordan de vibrerer, men kunne det tænkes at vejlængden ikke ændrer sig når E og F vibrerer? Kan fotoner slukke hinanden? Normalt blive der blot mere andre steder, som for lys/radiobølger. I kvanteeksperimenter er forklaringerne ofte det mest specielle.

Lad os ændre attenuatoren så kun 10 eller 1% kommer igennem. Hvordan kan bare nogle få fotoner slippe igennem uden påvirkning af dæmpningen? Det må være meget specielle bølgepakker, når de fleste forsvinder helt og nogle få slipper igennem upåvirkede.

Lad os ændre attenuatoren så kun 10 eller 1% kommer igennem. Hvordan kan bare nogle få fotoner slippe igennem uden påvirkning af dæmpningen? Det må være meget specielle bølgepakker, når de fleste forsvinder helt og nogle få slipper igennem upåvirkede.

Hej Svend

Ja, det er kvantemekaniske "energipakker":

For at jeg (eller andre) skal kunne svare, skal man vide hvilken form for attenuator (dæmper) du mener.

Mener du: * halv reflekterende spejl * halv dæmpende spejl * halv transparent dæmper

Hvordan er "dimsen" designet kvantemekanisk?

Her er nogle af de kvantemekaniske måder et foton kan vekselvirke med "noget andet": * https://en.wikipedia.org/wiki/Compton_scat... * https://en.wikipedia.org/wiki/Beam_splitter (kommer i flere versioner) * "spejling" ...

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Forklaringer:

Compton scattering: Citat: "... In Compton's original experiment, the energy of the X ray photon (≈17 keV) was very much larger than the binding energy of the atomic electron, so the electrons could be treated as being free. The amount by which the light's wavelength changes is called the Compton shift. ... The effect is significant because it demonstrates that light cannot be explained purely as a wave phenomenon. Thomson scattering, the classical theory of an electromagnetic wave scattered by charged particles, cannot explain shifts in wavelength at low intensity: classically, light of sufficient intensity for the electric field to accelerate a charged particle to a relativistic speed will cause radiation-pressure recoil and an associated Doppler shift of the scattered light,[2] but the effect would become arbitrarily small at sufficiently low light intensities regardless of wavelength. Thus, light must behave as if it consists of particles, if we are to explain low-intensity Compton scattering. Compton's experiment convinced physicists that light can behave as a stream of particle-like objects (quanta), whose energy is proportional to the light wave's frequency. ... If the photon is of low but sufficient energy (in general a few eV to a few keV, corresponding to visible light through soft X-rays), it can eject an electron from its host atom entirely (a process known as the photoelectric effect), instead of undergoing Compton scattering. High energy photons (1.022 MeV and above) may be able to bombard the nucleus and cause an electron and a positron to be formed, a process called pair production. ..."

Kig også i: * https://en.wikipedia.org/wiki/Category:Fou...

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Spejling:

Mirror in the atomic level…: Citat: "... Before that, let me phrase that electromagnetic waves don’t have magnetic fields. You may well shout at me, “Are you drunk?”. No, but that’s sorta truth. Magnetic fields are a consequence of electric fields along with a pinch of special relativity. ... So, it’s these electric fields we should be concentrating for now. ... The common explanation goes like this. A light photon interacts with an electron in the atom of the material, by which it gets absorbed and then, re-emitted. The net effect of all these absorption & re-emission is what we perceive as reflection. This is a bit misleading. Because, this isn’t what’s really going on… ... Classical electrodynamics says this. The incoming photon can be thought to have wave-like behavior. ... Think of this. As there’s no such thing as conservation of photon numbers, the photons can be destroyed and created. But, there’s a constraint. Either the photons are absorbed by the material (destructive interference) as a whole, or just transmitted (refracted or reflected) as a whole. ... Is that all? No, it’s confusing. How? One question. How do these dipoles exactly know where to put the photon back? ... Answer: The dipoles are not at all synchronized. The photon emission is a random process and it can be emitted anywhere, towards some angle which doesn’t agree with the law of reflection, even towards the source itself. Woah… ... This is where quantum electrodynamics rushes in. That’s why I told you to watch QED lectures last time. Anyways, the theory goes like this. Firstly, it just doesn’t make any sense to speak out that a photon interacts with a specific atom, nor it follows a definite path. It’s a quantum particle. It can interact with all the atoms, or take all the possible paths it can, and you can’t say anything about it. ... It should be noted that this is a collective phenomena. I mean, there’s no such thing as, “a photon interacts with an electron“. It can interact with a lot of electrons, all at once. And, it does. But, you can’t observe it. The interactions lead to corresponding phase differences, that either add up or cancel out as a whole (interference). The whole business going on here, can be burned down to a single technical phrase. A photon follows a geodesic path, which simply is a straight line in a 2D flat space (which isn’t really necessary here, but I can’t resist). [hjælp!] ..."

How do mirrors reflect light if photons are smaller than atoms?: Citat: "... Photons have no definite size until measured. This is a common quantum mechanical oddity that has no parallel in our more intuitive, classical world. "A photon has a zero size" means... ... Until detected, it is possible to demonstrate that a single photon wave can extend more than the size of a galaxy. Our current interpretation of a mirror reflecting a photon is that the wave characteristics of the photon dominates a mirror reflection and as long as the mirror appears smooth at the photon's wavelength scale, a reflection will take place. For photons whose wavelength is about the size of an atom (gamma rays), there is no reflection - it is rather scattering but even here the wave nature is more useful for analysis than the particle, although you can choose either way to perform your quantum-mechanics-compliant analysis and predict the same results. ..."

How do mirrors reflect photons?: Citat: "... In a quantum-mechanical picture, light consists of photons, or packages of optical energy. The photons of the light reflected from a metal (or a dielectric mirror) are identical to the incident ones, apart from the changed propagation direction. The loss of light in the metal means that some fraction of the photons are lost, while the energy content of each reflected photon is fully preserved. Which of the photons are lost is a matter of chance; there is a certain probability for each photon to be absorbed. [] So if one illuminates a metal with a source of single photons, there will be complete reflection (and no heating of the metal) in most cases [] and complete absorption with associated heating (creation of so-called phonons in the metal) in some cases. ..."

• halv transparent dæmper

Det er dette jeg tænker på, som en ren resistiv attenuator, en "grå" masse, der blot omdanner noget af em feltet til varme. Spejling og scatter er forståeligt, da nogle af de såkaldte fotoner fjernes ved afbøjning. Måske er det min forståelse og de almindelige forklaringer af fotoner der halter. Mine overvejelser ville jo give mening, hvis det først var målingen der gav en diskret "foton"effekt. Og alligevel kan atomer/molekuler udsende diskrete energipakker, men er det lykkedes på kontrolleret vis at producere enkelte fotoner?

Og alligevel kan atomer/molekuler udsende diskrete energipakker, men er det lykkedes på kontrolleret vis at producere enkelte fotoner?

Ja!:

Enkelt-foton-udsendere:

Oct. 15, 2010 Changing the Color of Single Photons Emitted by Quantum Dots: http://www.sciencedaily.com/releases/2010/... Citat: "... "The quantum dot can act as a true single photon source," says Srinivasan. "Each time we excite the dot, it subsequently releases that energy as a single photon. In the past, we had little control over the wavelength of that photon, but now we can generate a single photon of one color on demand, transmit it over long distances with fiber optics, and convert it to another color." ... The paper describes how the wavelength conversion of the photons improved their detection sensitivity by a factor of 25 with respect to what was achieved prior to conversion. ..."

Aalto University. (2016, July 8). New record in microwave detection. ScienceDaily: Citat: "... "Existing superconducting technology can produce single microwave photons. ..."

To sammenfiltrede-fotoner-udsendere:

Jun 5, 2010, Entangling photons with electricity: Citat: "... a new device called an "entangled light-emitted diode" (ELED) ... The ELED differs from an ordinary LED in that it contains quantum dots – tiny nanometre-sized islands of semiconductor. ... The quantum dot can be tuned to capture two electrons and two holes, which puts the system into a "biexciton" state. This then decays into a ground state through one of two intermediary exciton states, the pathway determining the polarization of the resulting pairs of photons. If the fine structure splitting between these two states is approximately zero then the only way to determine the decay path is to measure the polarization of the photons – the photons are, therefore, said to be entangled. ... The device emits individual entangled pairs of photons when a pulsed current is applied and has an "entanglement fidelity" of 0.82 ..."

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Enkelt-foton-detektorer:

High-speed superconducting single photon detectors for innovative astronomical applications

University Saarland (2013, October 25). Physicists aim to make transition to quantum world visible. ScienceDaily: Citat: "... Wilhelm-Mauch has already developed a highly efficient microwave detector that can detect photons with 100% efficiency. ..."

July 19, 2016, The birth of quantum holography—making holograms of single light particles: Citat: "... "We performed a relatively simple experiment to measure and view something incredibly difficult to observe: the shape of wavefronts of a single photon," says Dr. Radoslaw Chrapkiewicz. ..."

Det er dette jeg tænker på, som en ren resistiv attenuator, en "grå" masse, der blot omdanner noget af em feltet til varme.

Kig på den tidligere link med titlen "How do mirrors reflect photons?".

Mine overvejelser skyldes måske at alt lys/em-stråling efterhånden kaldes fotoner. Dualiteten mellem bølge og "partikel" er ofte helt fraværende, og det giver nogle mærkelige forklaringer, når partikelegenskaberne skal være eneste repræsentation. Jeg er af og til stødt på kvantemekaniske eksperimenter, hvor forskeren har sagt, at det kunne også forklares uden kvantemekanisk formalisme. P.S. Åbenbart kan man lave enkelt fotoner https://ing.dk/blog/en-foton-og-en-foton-o...

I 1900 fandt den tyske fysiker Max Planck dog en alternativ måde at beregne strålingen på, som baserede sig på, at legemet kun udvekslede energi med omgivelser i bestemte sprint. <<

Jo, så har historieskrivningen vel set ud, men jeg synes nu at det på tide at erkende at allerede det periodiske system med elektronskaller med ganske bestemte antal elektroner ikke rummede mulighed for andet end netop kvantespring, så det er egentlig mærkeligt at man skulle helt hen til Planck og Bohr før den store diskussion om energikvanta kom i gang.

John Larsson

Ja det har være meget svært for forskerne, at danne sig et billede af kvantaverdenen - og det har taget utrolig mange eksperimenter, at blive overbevist om at fysikken virkelig er som den er - selv i dag er der mange tilhængere af ideen om at kvantemekanikken er ukomplet som Einstein mente - at resultaterne på en eller anden måde må kunne give en bedre mening, en mening, som vi kan forstå med de systemer vi har - men som sagt tidligere, Bohr var den første, til at forstå, at kvantemekanikken er den sande forståelse af naturen, at det er os mennesker der må rette ind efter naturen og ikke naturen der skal rette ind efter os mennesker. jeg har somme tider tænkt på, at der findes mange forhold i naturen, som for os mennesker er dybt uforståelige og som ikke kan genskabes af mennesker - vi kommer nok ikke til at forstå og beherske alting.

Vi kommer nok aldrig til at forstå Verden, men måske dens regler?

I tradition med Newton m.fl. opfattes verden som opbygget af punktformige partikler, og denne opfattelse tvinges ned over forklaringer på kvantemekaniske fænomener. Bare ordet mekanik indikerer en partikelopfattelse. Jeg tror, at vi fra starten skal opfatte "kvateteorien" som en feltteori - hvilket også er tilfældet, når vi betragter mange partikler. Dvs. der er kun felter, og exitationer i disse felter opfattes som partikler, hvis feltet giver anledning til et tilstrækkelig (i rummet) defineret område.

Med en partikelopfattelse er dobbelt-spalte eksperimentet et paradoks, som vi med en partikelopfattelse giver mere eller mindre uheldige forklaringer på. Med en feltopfattelse er der ikke noget paradoks - for der ikke nogen elektron/foton - kun i målesituationen bestemmes sandsynligheden for en vekselvirkning med en detektor, som "oversættes" til en lokaliseret partikel.

Derfor den lidt provokerende overskrift. Opfat kvantemekanikken som en feltteori (kvantefelt-teori) og ikke som en mekanisk teori.

G.M. Holst

Nov 26, 2013, physicsworld.com: Physicists ask photons 'Where have you been?': Citat: "... A new version of the famous double-slit experiment has allowed physicists in Israel to measure a phenomenon that is bizarre even by the counterintuitive standards of quantum mechanics. By placing a double-slit experiment along one path of a larger double-slit experiment, the researchers have shown that photons traverse a section of the apparatus that they neither enter nor exit.

Dette er et eksempel på at forklaringerne er mere fantastiske end eksperimentet. Lyset kommer skam ind, men det ledes altsammen ud vinkelret på den ønskede udgang. Lidt af virkeligheden afsløres her "Oscillating the mirrors does itself change the pathlengths, thereby destroying the perfect destructive interference between the two paths of the inner interferometer and allowing the wavefunction to leak out."

Interferometeret er snedigt, fordi interferensen er ens for alt lys der kommer igennem, næsten uanset hvorledes det rammer den første splitter. Stilles det til destruktion i det ønskede output (alt lys kommer så ud vinkelret på sidste splitter/kombiner, er det klart at spejlene E og F intet betyder, men spejlene A og B vil ødelægge den destruktive interferens, og noget kommer ud. Det er ikke meget anderledes end en tryllekunstner, der får folk til at se noget mystisk, som ikke er der.

Jeg har i øvrigt set opstillingen før, og tvivlet lidt på forklaringen, men nu er jeg mere sikker på at der ikke er noget mystisk kvantehalløj.

Jeg har i øvrigt set opstillingen før, og tvivlet lidt på forklaringen, men nu er jeg mere sikker på at der ikke er noget mystisk kvantehalløj.

Hej Svend

"Kvantemoralen" er, at prøver man at snyde sig til "forbudt kvanteinformation" fx via weak measurement, giver eksperimentet "pludderresultater"?

Physicists ask photons 'Where have you been?': Citat: "... "From my perspective, it's really interesting to understand why you get the results you do," says Hosten, adding "but it's also interesting that a weak measurement gives you some disconcerting answers." ..."

Perimeter Institute for Theoretical Physics. (2014, September 24). Are weak values quantum? Don't bet on it: Key technique used to probe quantum systems may not be so quantum after all. ScienceDaily: Citat: "... But what if we could look "a little"? Well, that's a weak measurement, a concept which is central to the notion of a weak value. The basic idea of weak measurement is to gain a little bit of information about a quantum system by only disturbing it a little bit; by doing this many times, one can ultimately gain quite a bit of information about the system. Weak measurements have applications in quantum information technologies such as quantum feedback control and quantum communications. ... "On the one hand, the quantum world can be weird, of course," he says. "But on the other hand, we need to work carefully to distinguish between genuinely quantum effects and effects that can be replicated classically." ... "Statistics can fool you," says Combes. "We think this particular weak value puzzle is a statistical question, not a fundamentally quantum question. There might be something genuinely quantum about weak values, but to my eye that's not clear yet." ... "Don't get me wrong: mystery is great," he says. "I want there to be mystery -- that's why I'm in this field. But shouldn't we be trying to get to the bottom of things, rather than making them more mysterious than they really are? I think we need to carefully question what weak values really tell us. Chris and I are hoping this paper will spark some of that questioning." ..."

Eksempler:

University of Rochester. (2013, March 3). Getting around the uncertainty principle: Physicists make first direct measurements of polarization states of light. ScienceDaily: Citat: "... The direct measurement technique employs a "trick" to measure the first property in such a way that the system is not disturbed significantly and information about the second property can still be obtained. This careful measurement relies on the "weak measurement" of the first property followed by a "strong measurement" of the second property. ..."

University of Rochester. (2014, August 28). Doing more with less: New technique uses fraction of measurements to efficiently find quantum wave functions. ScienceDaily: Citat: "... Just two years ago, with the advent of a technique called direct measurement, scientists discovered they could reliably determine a system's wave function by "weakly" measuring one of its variables (e.g. position) and "strongly" measuring a complementary variable (momentum). Researchers at the University of Rochester have now taken this method one step forward by combining direct measurement with an efficient computational technique. The new method, called compressive direct measurement, allowed the team to reconstruct a quantum state at 90 percent fidelity (a measure of accuracy) using only a quarter of the measurements required by previous methods. ..."

University of Rochester. (2008, August 8). Physicist's Quantum-'Uncollapse' Hypothesis Verified. ScienceDaily: Citat: "... Most scientists have believed that the instant a quantum object was measured it would "collapse" from being in all the locations it could be, to just one location like a classical object. Jordan proposed that it would be possible to weakly measure the particle continuously, partially collapsing the quantum state, and then "unmeasure" it, causing the particle to revert back to its original quantum form, before it collapsed. ... In the latest issue of Nature News, Postdoctoral Fellow Nadav Katz explains how his team put the idea to the test and found that, indeed, he is able to take a "weak" measurement of a quantum particle, which triggered a partial collapse. Katz then "undid the damage we'd done," altering certain properties of the particle and performing the same weak measurement again. The particle was returned to its original quantum state just as if no measurement had ever been taken. ..."

Jul 22, 2010, nature.com: Quantum theory survives its latest ordeal: Citat: "... Now, Gregor Weihs of the University of Innsbruck in Austria and colleagues at the University of Waterloo in Canada have done a three-slit experiment that shows there is no third-order interference. ... "The existence of third-order interference terms would have tremendous theoretical repercussions - it would shake quantum mechanics to the core", he said. ... [Fra kommentarer:] The weirdest bit for me is that blocking a slit is the same as making a measurement (you know that zero photons go through that slit). So I would have thought that this would somehow change the outcome of the experiments so that they wouldn't add up? ... Blocking the third slit does change the outcome. Two slits produces a different interference pattern than three slits. What the experiment shows is that no terms are needed beyond summing the amplitude from all paths. Specifically, one does not need to consider all paths pair-wise. Nor does one need a term dependent upon the number of paths. Adding or blocking a path does change the result - in a way consistent with the simple equation we've always used. ..."