254 Matching Annotations
  1. Nov 2022
    1. Diseases don’t have to follow rules.

      Reminds me of something Carl Sagen said - I think it was Sagen though might have been Feynman - in the context of quantum physics, that the universe is under no obligation to observe our rules, or something like that.

  2. Oct 2022
    1. The values ±μB do thus not correspond to the continuum of values −μ·B Einsteinand Ehrenfest had conjectured. The energy term V = −μ·B is a macroscopic quantity. It is a statistical average overa large ensemble of fermions distributed over the two microscopic energy states ±μB, and as such not valid for in-dividual fermions.
      • SEE
    2. the fermions precess around the magnetic-field just likeEinstein and Ehrenfest had conjectured.
      • CLARO, el "VECTOR" de spin no APUNTA, sino que "PRECESA"
    3. he exact theory of the Stern-Gerlach experiment andwhy it does not imply that a fermion can only have itsspin up or downGerrit Coddens
      • THESIS
    1. Medidas Stern-Gerlach sucesivas sobre electrones (imagen del libro «La realidad cuántica», de RBA ediciones, colección «Un paseo por el cosmos», número 32).
      • REVISAR porcentajes
      • salida del segundo S_G

      • Ver Anottation

      • los % se aplican sobre el ORIGINAL, no para cada caso

      • el segundo SG deja pasar el 100% de los que entran, sin "cambiar" nada y los "desvia" hacia el (-)
      • en la figura parece "recto": no es correcto
    2. Tal y como cuenta Gerlach en sus memorias la plata estaba reaccionando con los vapores de mercurio que provenían de su respiración y de los cigarrillos que fumaba habitualmente»
      • ok, historia
    3. En los modelos pre-cuánticos de la época del experimento, ese solitario electrón era supuesto en órbita en torno al núcleo del átomo y el conjunto de capas electrónicas internas llenas, siendo él solo el responsable del momento magnético, al aportar los restantes electrones una contribución neta nula al momento angular
      • ok, interpretacion de S-G
      • CUANTIZACION ESPACIAL!
    1. “En esta tesis doctoral describimos por primera vez la evolución en el tiempo de los experimentos de Stern-Gerlach consecutivos
      • SEE
    1. En este caso, la emisión del fotón ocurre sin que el electrón cambie su órbita en torno al núcleo atómico, lo único que cambia es el sentido de su orientación. Este fenómeno de hecho ocurre y ha sido observado. El ejemplo más importante, históricamente hablando, ocurrió en los años treinta del siglo XX cuando se descubrió un “silbido” de radiofrecuencia que variaba en un ciclo diario y que parecía ser de origen extraterrestre. Tras sugerencias iniciales de que este “silbido” pudiera ser ocasionado por el Sol, se observó que las ondas de radio parecían venir del centro de la galaxia. Estos descubrimientos fueron publicados en 1940, y fue Hendrik van der Hulst quien en 1944 descubrió que el hidrógeno neutral podía producir una radiación con una frecuencia de 1420.4058 MHz a causa de dos niveles de energía cercanamente espaciados correspondientes al estado basal (fundamental) del hidrógeno. De este modo, la línea de 21 centímetros (1420.4 MHz) fue detectada por vez primera en 1951,
      • SEE
    2. en el experimento Stern-Gerlach no se hace saltar al electrón de una capa energética discreta a otra. Estamos entonces ante otro tipo de fenómeno que no involucra “saltos” de energía y en el cual el número cuántico n del nivel de energía en que se encuentra cada átomo permanece igual antes y después de pasar por un aparato Stern-Gerlach, lo cual nos obliga a ir pensando ya en la adjudicación de un nuevo número cuántico al átomo que es independiente del número cuántico que caracteriza a la energía del átomo. Fue precisamente el físico teórico Wolfgang Pauli el que sugirió la adopción de un nuevo número cuántico, un cuarto número cuántico a ser agregado a los otros tres números cuánticos que ya se conocían, simbolizado como s. Y aunque éste nuevo número cuántico resulta ser una propiedad que depende en forma intrínseca del electrón
      • ok
    3. Lo que sucede en el experimento Stern-Gerlach es de naturaleza eminentemente magnética. Al igual que como ocurre con la aguja magnetizada de un compás que tiende a alinearse en el sentido Norte-Sur, algo en el átomo debe estar actuando también como un pequeño imán que lo hace alinearse con el campo magnético que le es aplicado. Expresamos esto formalmente diciendo que los campos magnéticos ejercen fuerzas sobre objetos y partículas que tienen momentos magnéticos. Estas fuerzas son bien comprendidas, y las mismas reglas parecen aplicar para objetos macroscópicos que para objetos sub-microscópicos
      • SEE
    1. -P: Pero cuando hablas de preguntas, te refieres a mediciones, ¿no?. -R: Sí, mediciones. Tenemos un determinado observable físico, anotamos el resultado, a continuación sobre ese mismo sistema, otro. Además son observables sencillos, solo tienen dos posibles valores, + 1 o -1. A continuación medimos un segundo, anotamos, y a continuación medimos un tercer observable físico. Hay seis situaciones distintas, y éstas involucran nueve medidas diferentes. Son seis situaciones medidas de tres observables, uno tras otro. Hay una desigualdad que se tiene que cumplir en cualquier teoría de las llamadas de variables ocultas no-contextuales que dice que tiene que ser como mucho 4. La mecánica cuántica, en un caso ideal, si no tuviésemos ningún tipo de imperfecciones, tendría que salir 6. En el experimento, que tiene ciertas imperfecciones inevitables, no llega a salir 6, pero sale 5,5. Sobre conjuntos mínimos de contextos cuánticos: A. Cabello, «El teorema Kochen-Specker llega al laboratorio«, Investigación y Ciencia 461 (2015) 8-9.
      • SEE
      • A. Cabello
    2. Pruebas experimentales de la contextualidad
      • SEE
    1. Bibliografía [GAL-89] A. Galindo y P. Pascual, Mecánica Cuántica I, Eudema, Madrid, 1989. A. Einstein, B. Podolsky and N. Rosen, Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?, Physical Review 47 (1935) 777-780. G. García Alcaine, Enredo cuántico (también en Enredo cuántico). E. Schrödinger, Discussion of probability relations between separated systems, Proceedings of the Cambridge Philosophical Society 31 (1935) 555-562. Density Matrix Formalism: http://www.cithep.caltech.edu/~fcp/physics/quantumMechanics/densityMatrix/densityMatrix.pdf http://www.pa.msu.edu/~mmoore/Lect34_DensityOperator.pdf http://pages.uoregon.edu/soper/QuantumMechanics/density.pdf http://ocw.mit.edu/courses/chemistry/5-74-introductory-quantum-mechanics-ii-spring-2009/lecture-notes/MIT5_74s09_lec12.pdf K.T. McDonald: Density-Matrix Description of the EPR «Paradox«
      • SEE
      • GG Alcaine
      • Schrodinger 1935
    2. Advertencia: correlaciones cuánticas sin entrelazamiento: Correlaciones cuánticas clásicamente inalcanzables en sistemas sin entrelazamiento: Una demostración experimental de la violación de las desigualdades de Kochen y Specker para un único sistema cuántico, un fotón que puede viajar a lo largo de tres caminos posibles donde se realizan diferentes medidas cuyos resultados deben ser compatibles entre sí: R. Lapkiewicz et al, «Experimental non-classicality of an indivisible quantum system», Nature 474 (2011) 490-493. En análisis de A. Cabello: A. Cabello, «»Correlations without parts», Nature 474 (2011) 456-458: Kochen and Specker noticed that quantum mechanics is in conflict with classical physics even for non-composite systems. This conflict can be converted into experimentally testable violations of classical correlation inequalities and into experiments showing that quantum correlations occur for any quantum state, not necessarily just for entangled ones. (Lapkiewicz and colleagues´) findings are therefore of fundamental importance, because they confirm that quantum correlations also occur in system in which entanglement, which is supposed to be the most emblematic feature of quantum mechanics, cannot be defined. It seems that Bell experiments, composite systems and entangled states are not enough to provide a complete understanding of the physical principles behind quantum mechanics: quantum correlations exist without them.
      • ATENCION
    1. Bibliografía [BOH-79] Bohm, D., Quantum Theory, Dover, 1979. [ESP-95] Espagnat, B.d’; Veiled Reality. An analysis of Present-day Quantum Mechanical Concepts, Addison-Wesley, 1995. [FER-96] Ferrero, M., Fernández-Rañada, A., Sáchez-Gómez, J.L. y Santos, E.; Fundamentos de Física Cuántica. Curso de verano de El Escorial, Complutense, Madrid, 1996. [JAM-74] Jammer, M.; The philosophy of Quantum Mechanics,Wiley, 1974. [SEL-88] Selleri, F., ed.; Quantum Mechanics Versus Local Realism. The Einstein-Podolsky-Rosen Paradox, Plenum, New York, 1988. A. Cabello: Tesis doctoral: Pruebas algebraicas de imposibilidad de variables ocultas en mecánica cuántica. C. Saulder: Contextuality and the Kochen-Specker Theorem.
      • SEE
      • tesis de A, Cabello
    2.  Como ilustración adicional, puede consultarse la excelente divulgación sobre el tema: Cassinello; Rev. Esp. Fís., dic. 1997, p. 52. A. Cassinello and A. Gallego, The quantum mechanical picture of the world, American Journal of Physics 73, 3 (2005); pp. 273-281.
      • SEE
    3. El teorema de Bell-Kochen-Specker (1966-1967) divulgó y generalizó la aceptación de la contextualidad cuántica (en realidad establecida ya en el teorema de Gleason de 1957), una propiedad cuántica más general que la no-localidad (¡entendida ésta a la Bell!, véase el apartado terminología en la entrada sobre el teorema EPR), y existen ya experimentos realizados que han probado la contextualidad cuántica.
      • see
      • IMPORTANT
      • NO-contextualidad > no-localidad
  3. www.fisicacuantica.es www.fisicacuantica.es
    1. La realidad cuántica, por María C. Boscá: Un libro que introduce y divulga la mecánica cuántica. En la colección Un paseo por el cosmos, de RBA ediciones:
      • Autora del blog
    1. Bibliografía [BEL-90] Bell, J.S.; Lo decible y lo indecible en mecánica cuántica, Alianza Univ., 1990. [ESP-76] Espagnat, B.d’; Conceptual Foundations of Quantum Mechanics, Benjamin, 1976. [GAL-89] Galindo, A. y Pascual, P.; Mecánica Cuántica, Eudema, Madrid, 1989. [ICA-91] Icaza, J.J.; La construcción de la Mecánica Cuántica, Univ. del País Vasco, Bilbao, 1991. [JAM-74] Jammer, M.; The philosophy of Quantum Mechanics,Wiley, 1974. [NEU-91] Neumann, J. von; Fundamentos matemáticos de la Mecánica Cuántica, Consejo Superior de Investigaciones Científicas, Madrid, 1991. [SEL-88] Selleri, F., ed.; Quantum Mechanics Versus Local Realism. The Einstein-Podolsky-Rosen Paradox, Plenum, New York, 1988. [WHE-83] Wheeler, J.A. y Zurek,W.H., eds.; Quantum Theory and measurement, Princenton Univ., Princenton, 1983.
      • SEE
    2. 1. Cuando en 1952 Bohm publicó su teoría de V.O., fue completamente ignorada, a pesar de que su mera existencia como teoría de V.O. determinista (no local) capaz de reproducir los resultados de la M.C. (no relativista) debiera haber suscitado la atención, al menos sobre cómo era posible su misma existencia. 2. Bell ha narrado como, atraído fuertemente por el argumento EPR y la posibilidad relacionada de elaborar una descripción teórica más completa que la de la M.C., en cuanto tuvo conocimiento de que von Neumann había demostrado su imposibilidad abandonó el tema. Posteriormente, sin embargo, «al ver lo imposible realizado», decidió analizar cómo era posible, es decir, si es que el teorema de von Neumann era erróneo: J.S. Bell, «On the impossible pilot wave», Foundations of Physics, 12 (1982) 989-999; trad. en [BEL-90], pp. 221-233.
      • ok
    3. famosa prueba de imposibilidad de V.O. que realizó von Neumann en 1932, el tema quedó “dormido”, hasta que D. Bohm, en 1952, conseguiría revitalizarlo
      • ok
    4. Born como Heisenberg, en sus artículos básicos “demoledores” del indeterminismo, sobre la interpretación probabilística de ψ y las relaciones de indeterminación
      • see
    1. Algunos enlaces: Sven Aerts, Paul Kwiat, Jan-Ake Larsson and Marek Zukowski; Two-photon Franson-type experiments and local realism. https://qutools.com/qued/qued-sample-experiments/sample-experiments-franson-interference/ https://www.researchgate.net/publication/348741037_The_Franson_experiment_revisited Two-photon Franson-type experiments and local realism
      • see
    1. Figura del montaje experimental del doble cristal de Zou-Wang-Mandel; fuente: http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.67.318.
      • see
    1. Like most experiments, this one can be confusingif you think about it the wrong way (e.g.,semiclassically), but is simple & unambiguous if you remember the Feynman rules.
      • ok
    1. However, this point of view cannot explain the results of measurementswith respect to a different basis
      • Y con MISMO ANGULO???
      • ver anterior comentario
    2. Einstein, Podolsky and Rosen proposed that each particle has some internal state thatcompletely determines what the result of any given measurement will be. This state is,for the moment, hidden from us, and therefore the best we can currently do is to giveprobabilistic predictions. Such a theory is known as a local hidden variable theory. Thesimplest hidden variable theory for an EPR pair is that the particles are either both instate |0〉 or both in state |1〉, we just don’t happen to know which. In such a theory nocommunication between possibly distant particles is necessary to explain the correlatedmeasurements
      • STATE = 00 + 11
      • IMPORTANT: el "estado" en cada lado, esta "fijado" desde el origen. Entonces, Psi es SEPARABLE, no ENTANGLED
      • PERO... como el polarizador formara un ANGULO respecto al "vector" de cada lado,
      • Segun la INTERPRETACION PROBABILISTA, hay 2 posibles resultados en CADA lado, salvo el caso particular (pequeño % al repetir muchas veces) de que "vector" COINCIDA con el polarizador!!!
      • Caso: 2 polarizadores con mismo ANGULO!
      • Al COMPARAR resultados de los 2 lados, DEBERIAN darse los 4 CASOS: 00, 11, 01, 10
    3. Further analysis, as we shall see, showsthat even though there is a coupling between the two particles, there is no way for Alice orBob to use this mechanism to communicate
      • AS WE SHALL SEE
      • where?
    4. he others are reflected
      • REFLECTED ???
      • or ABSORBED ???

      • Google: quora

    5. Those that are reflected by the filter all have polarization |↑〉.
      • INTERESTING !
      • SEE REFERENCES
    6. Measurement of a state transforms the state into one of themeasuring device’s associated basis vectors
      • Esto es INTERPRETACION MATEMATICA
    7. The measurement postulate of quantum mechanics states that any device measuring a 2-dimensional system has an associated orthonormal basis with respect to which the quantummeasurement takes place.
      • 2 "POSIBLES" RESULTADOS => 2 "EIGENSTATE" => 2 DIMENSIONS => (X, Y) EJES "ORTOGONALES"
    8. Finally, after filter B is inserted between A and C, a small amount of light will be visibleon the screen, exactly one eighth of the original amount of light
      • CALCULO:
      • A = I/2
      • B = A/2
      • C = B/2
      • I x (1/2) x (1/2) x (1/2) = I / 8
    1. John Bell at CERN around 1982. Bell seems to be contemplating Alain Aspect’sexperimental scheme with variable polarizers5 for testing the inequalities now bearingBell’s name. The left-hand-side part of the inequality on the blackboard (describing thecorrelations between different measurement outcomes in the experiment sketchedbelow) is ≤2 in a local realism view of the world a la Einstein (top) and equal to2 2 inquantum mechanics (bottom). Image courtesy of CERN
      • HISTORIC PHOTO!
      • AUTHOR???
    1. Any forumthat invites contributions on the topic ofquantum mechanics is likely to receive anumber of submissions from enthusiastswith little to no expertise in studyingfoundational questions
      • OK
      • Example: Apeiron
    2. owever, JohnStewart Bell proved4 that such an approachcannot explain the quantum mechanicaloutcomes
      • NO, NO and NO!!!
      • Bell's work to try to distinguish, NOT PROVED!!!
      • ONLY for "LOCAL" HV
      • See next statement: "Any theory that uses hidden variables still requires non-local physics."
    3. Thischange is instantaneous and so seems toviolate the physical law that no informationcan travel faster than the speed of light
      • "CHANGE" "IS" "INSTANTANEOUS": => NOT PHYSICAL (in the SR sense)
      • WARNING: "THEY" (who?) say: "no transmision of info"
    4. the outcome of measuring one particledetermines the state of the other.
      • WARNING: "change" in Psi === "collapse"
      • See Schrodinger-1935: measure in A "RESOLVES" the entanglement: From Psi (A+B) => Psi (A) + Psi (B)
    5. By the rulesof quantum mechanics, a measurementof which state the system is in producesa probabilistic outcome.
      • WARNING: "nature" of "probability"?
      • ENSEMBLES interpretation: Ballentine, Einstein

      • WARNING: Psi =?= (physical) state

      • Psi "interpretations"
    6. But, as with searches beyondthe standard model in particle physics,there is no guarantee that experiments willfind anything new in the near term
      • OK
    7. the dynamics of awavefunction collapse has never beenobserved
      • SEVERAL proposals
      • DECOHERENCE
    8. Quantumsystems can be in a superposition of statesbut when measured by a classical observerthese are apparently collapsed to a classicaloutcome
      • WARNING: distinction between PURE and MIXED states
      • OR states == conocimiento
      • "PURE" SUPERPOSITION ==
    9. we learn theaxioms of quantum mechanics and how toapply these rule
      • AXIOMS: why "invent"?
      • HOW TO APLY RULES: who decides?
    1. One can even set up quite ridiculouscases. A catis penned up in a steel chamber,along with the fol-lowing diabolical device (which must be securedagainst directinterferenceby the cat): in a Geigercounterthereis a tinybit of radioactivesubstance,sosmall,that perhaps in the course of one hour one ofthe atoms decays, but also, with equal probability,perhaps none; if it happens, the countertube dis-chargesand througha relayreleasesa hammerwhichshattersa small flask of hydrocyanicacid. If onehas leftthis entiresystemto itselffor an hour, onewould say thatthe cat stilllives ifmeanwhileno atomhas decayed. The firstatomic decay would havepoisoned it. The q+-functionof the entire systemwould expressthis by havingin it the livingand thedead cat (pardon the expression) mixed or smearedout in equal parts.It is typicalof these cases that an indeterminacyoriginallyrestrictedto the atomic domain becomestransformedinto macroscopicindeterminacy,whichcan then be resolved by direct observation. Thatprevents us from so naively accepting as valid a"blurred model" for representingreality. In itselfit would not embodyanythingunclear or contradic-tory. There is a differencebetweena shakyor out-of-focusphotographand a snapshotof clouds and fogbanks
      • CAT "PARADOX?": 2 PARRAFOS cortos
    2. I consider it acceptable to express thisreasoningsequenceas follows:Theorem 1: If different+-functionsare underdis-cussionthesystemis in differentstates.If one speaksonlyof systemsforwhicha +-functionis in general available,then the inverseof this the-oremruns:Theorem2: For the same +-functionthe systemisin thesamestate
      • Th 2: 1 Psi => "set" of predictions => 1 "state"
      • BUT DISTINCT states (different systems) COULD give "same" results

      • Th 1: JUST EPR: different measurements at A, give DIFFERENT Psi at B!!!

      • BUT, IMPORTANTLY, measurements at B give SAME results
    3. Let us pause for a moment. This result in itsabstractnessactuallysays it all: Best possibleknowl-edge of a whole does not necessarilyincludethe samefor its parts. Let us translatethis into terms ofSect. 9: The whole is in a definitestate, the partstakenindividuallyare not."How so? Surely a systemmust be in some sortof state." "No. State is +-function,is maximalsumof knowledge. I didn't necessarilyprovide myselfwiththis,I may have been lazy. Then the systemisin no state.""Fine, but then too the agnostic prohibitionofquestionsis not yet in forceand in our case I cantell myself:the subsystemis alreadyin some state,Ijust don'tknowwhich.""Wait. Unfortunatelyno. There is no 'I justdon't know'. For as to the total system,maximalknowledgeis at hand . . "The insufficiencyof the /-functionas model re-placementrests solely on the fact that one doesn'talwayshave it. If one does have it,thenby all meanslet it serve as descriptionof the state. But some-timesone does not have it, in cases whereone mightreasonablyexpectto. And in thatcase, one dare notpostulatethat it "is actually a particularone, onejust doesn't know it"; the above-chosenstandpointforbidsthis. "It" is namelya sum of knowledge;and knowledge,that no one knows,is none
      • PSI =?= "OUR" KNOWLEDGE?
      • vs Mermin's Quantum Bayesianism (QBism)
      • wikipedia
      • "For this reason, some philosophers of science have deemed QBism a form of anti-realism.[3][4]"
      • " Norsen[34] has accused QBism of solipsism"
      • "Rooted in the prior work of Carlton Caves, Christopher Fuchs, and Rüdiger Schack during the early 2000s, QBism itself is primarily associated with Fuchs and Schack and has more recently been adopted by David Mermin.[7] "
      • "Zeilinger and Brukner have also proposed an interpretation of quantum mechanics in which "information" is a fundamental concept, and in which quantum states are epistemic quantities.[69] "
      • wiki:Talk
      • "John von Neumann is identified as the first quantum Bayesian"
    4. There's no doubt about it. Every measurementisfor its systemthe first. Measurementson separatedsystems cannot directlyinfluenceeach other-thatwould be magic. Neithercan it be by chance,if froma thousandexperimentsit is establishedthatvirginalmeasurementsagre
      • SOLO se puede hacer UNA medida
      • INFLUENCIA a distancia==MAGIA
    5. Quantum pre-dictionsare indeed not subject to test as to theirfullcontent,ever, in a single experimen
      • OK. por tanto CONTEXTUAL
      • pensar caso EPR
    6. But one canrepeatthe experimentab ovo a thousandtimes; eachtimeset up thesame entanglement;accordingto whimcheckone or theotherof the equations
      • OK
      • repeticion, con mediciones DISTINTAS
      • pensar en BOHR: medicion DISTINTA => DISTINTO aspecto onda-corpusculo
    7. So one cannotcheckboth equationsin a single experimen
      • IMPORTANTE
      • para experimentos REALES con fotones
      • o "explicaciones" de Mermin
    8. A singlemeasurementof q or p or Q or P resolvesthe entanglementand makes both systemsmaximallyknown. A second measurementon the same systemmodifiesonly the statementsabout it, but teachesnothingmore about the othe
      • OK
      • The FIRST measurement resolves the entanglement, y dan "conocimiento" del OTRO lado
      • SIGUIENTES medidas SOLO "afectan" a un lado, no AFECTAN al conocimiento del OTRO lado
    9. The con-ceptual joining of two or more systems into oneencountersgreat difficultyas soon as one attemptsto introducethe principleof special relativityintoQ.M.
      • GRAN DESCUBRIMIENTO!
      • "problema" de la NO-LOCALIDAD en sistemas
    10. he electromagneticfield. Its laws are "relativitytheorypersonified,"a non-relativistictreatmentbeingin generalimpossible. Yet it was this field,whichintermsof theclassicalmodelof heat radiationprovidedthe firsthurdleforquantumtheory,thatwas the firstsystemto be "quantized."
      • EM == RELATIVISTA y CUANTICO
    11. t consists,tomentionthis briefly,at firstsimplyof the productof the two individualfunctions;which,since the onefunctiondependson quite differentvariablesfromtheother,is a functionof all these variables,or "acts ina space of much higherdimensionnumber"than theindividualfunction
      • OK,
      • Psi es "FUNCION" MULTIDIMENSIONAL >= 3
    12. When two systemsinteract,their+-functions,as wehave seen,do notcomeintointeractionbut rathertheyimmediatelycease to exist and a single one, for thecombinedsystem,takes their place
      • INTERESTING
      • Psi no describe individuos, sino TODO el sistema
      • Ejemplo: Psi de sistemas de fermiones: DEBE ser ANTISIMETRICA
    13. 7A. Einstein,B. Podolsky,and N. Rosen,Phys. Rev. 47:777 (1935). The appearanceof this work motivatedthepresent-shallI say lectureor generalconfession
      • EPR motivated Schodinger's cat ARTICLE
    14. 11. Resolutionof the"Entanglement."ResultDependenton theExperimenter'sIntentiontWe returnto the general case of "entanglement,"withouthaving specificiallyin view the special case,just considered,of a measurementprocess. Supposethe expectation-catalogsof two bodies A and B havebecomeentangledthroughtransientinteraction.Nowlet the bodies be again separated. Then I can takeone of them,say B, and by successivemeasurementsbringmyknowledgeof it, whichhad becomeless thanmaximal,back up to maximal. I maintain:just assoon as I succeed in this,and not before,then first,the entanglementis immediatelyresolvedand, second,I will also have acquired maximal knowledgeof Athroughthe measurementson B, makinguse of theconditionalrelationsthatwerein effect
      • IMPORTANT
      • Midiendo en B
      • Se "resuelve" el entanglement (correlacion debida a una conservacion)
      • Se "gana" conocimiento sobre A
    15. And what if we don't look? Let's say it wasphotographicallyrecorded and by bad luck lightreachesthe filmbeforeit is developed. Or we inad-vertentlyput in black paper instead of film. Thenindeed have we not only not learned anythingnewfromthe miscarriedmeasurement,but we have suf-feredloss of knowledg
      • MIRAR, DETECTAR, REGISTRAR
    16. f the two bodies have again separated,it is not again split into a logical sum of knowledgesabout the individualbodies.
      • NO SEPARABILIDAD en conocimiento de sistemas individuales
    17. The combined expectation-catalogconsistsinitiallyof a logical sum of the individualcatalogs
      • OK: conocimiento: catalogo de posibilidades/expectativas
    18. then there occurs regularlythat which I have justcalled entanglementof our knowledgeof the twobodies
      • ATENCION: "entanglement" del conocimiento!
    19. Any "entanglementof predictions"that takes placecan obviouslyonly go back to the fact that the twobodies at some earlier time formedin a true senseone system,that is were interacting,and have leftbehindtraceson each other
      • Sabine: las "correlaciones" (clasicas o cuanticas) tienen su origen en UN UNICO "evento" pasado
    20. A measurementon one cannotpossiblyfurnishany grasp of what is to be expected of the othe
      • EPR

    Tags

    Annotators

    1. E. Schrödinger, Die Naturwissenschaften, 48, 807 (1935); 49,823, 844 (1935). English trans. in Proc. Am. Philos. Soc. 124,323 (1980).
      • [CITATION] Naturwiss. 23, 807 1935; 23, 823 1935; 23, 844 1935; for the English translation see, JD Trimmer E Schrödinger - Proc. Am. Philos. Soc, 1980
  4. arxiv.org arxiv.org
    1. FIG. 6. Snapshots of the falling ball-chain with simultaneous drop of a steel ball. The free endof the chain (dark vertical line) falls faster than the steel ball (dark point on the right-hand side).The chain falls directly on a flat surface; note the formation of a compact heap at the bottom.Images are taken at intervals of 40 μs
      • SEE
    2. FIG. 1. Falling chain geometries. (a) The chain is falling vertically on a scale pan. During the fall,the apparent weight is predicted to be three times the deposited weight. (b) The chain is initiallyattached by its two ends at the same height. As one of the ends is released the acceleration of thechain tip is greater than g, the acceleration due to gravity. (c) The chain slides off a table by avertically hanging end. In this case the acceleration is predicted to be g/2
      • SEE
    1. 6 Is There a Paradox with Teleportation?My complaints about the (mis)interpretation of the word “teleportation” in Section IIshows that I am (over)sensitive about this issue. This is because I was thinking a lotabout it, resolving for myself a paradox [31] which I, as a believer in the Many-WorldsInterpretation (MWI) [32] had with this experiment
      • Vaidman == Many-Worlds int BELIEVER!
    1. Wieman, Carl. “How to Become a Successful Physicist.” Physics Today 75, no. 9 (September 2022): 46–52. https://doi.org/10.1063/PT.3.5082

      The details here are also good in teaching almost all areas of knowledge, particularly when problem solving is involved.

      How might one teach the practice of combinatorial creativity?

    1. 4 October 2022 The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2022 to Alain Aspect Université Paris-Saclay and École Polytechnique, Palaiseau, France John F. Clauser J.F. Clauser & Assoc., Walnut Creek, CA, USA Anton Zeilinger University of Vienna, Austria “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science”
      • CORRECT!
  5. Sep 2022
    1. We discuss “the plane wave approximation” to quantum mechanical scattering using simple one-dimensional examples. Our central claims are that (a) the plane waves of standard calculationscan and should be thought of as very wide wave packets, and (b) the calculations of reflection andtransmission probabilities R and T in standard textbook presentations involve an approximationwhich is almost never discussed. We present a simple and intuitively revealing alternative way toderive and understand the connection between asymptotic wave function amplitudes and scatteringprobabilities, which also has the benefit of bringing the approximate character of standard planewave calculations out into the light. We then develop an under-appreciated exact expression forscattering probabilities, using it to calculate, for two standard examples, expressions for R and T foran incident wave packet. Comparing these results to the corresponding probabilities calculated usingthe plane wave approximation helps illuminate the domain of applicability of that approximationand thus underscores the importance of thinking about scattering in terms of wave packets insteadof plane waves
      • GOOD!
    2. his result can be summarizedas follows:R =∫P (k)Rk dk (30)where P (k) = |φ(k, 0)|2 is the probability density for agiven k associated with the incident packet, and Rk issimply the reflection probability for a particular value ofk as expressed in Equation (6).
      • Eq (30)
    3. The rigorous way to calculate the reflection probabilityfor our wave packet is to use Equation (30).

      .

    4. FIG. 2: The top frame shows V (x) for the rectangular bar-rier. Subsequent frames show how |ψ(x)| evolves in time fora wave packet incident from the left, through an infinite se-quence of back-and-forth reflections inside the barrier. Notethat the sizes of reflected packets are exaggerated relative totransmitted packets, compared to the assumptions made inthe text
      • SEE
      • reflexion into the barrier
    1. I have a long list of ideas I want to pursue in cosmology, quantum mechanics, complexity, statistical mechanics, emergence, information, democracy, origin of life, and elsewhere. Maybe we’ll start up a seminar series in Complexity and Emergence that brings different people together. Maybe it will grow into a Center of some kind.

      https://www.preposterousuniverse.com/blog/2022/03/06/johns-hopkins/

      Somehow I missed that Sean Carroll had moved to Johns Hopkins? Realized today when his next book showed up on my doorstep with his new affiliation.

  6. Aug 2022
    1. The effects of this familiarity of phenomena have often been discussed.Wolfgang K ̈ohler, for example, has suggested that psychologists do not open up“entirely new territories” in the manner of the natural sciences, “simply becauseman was acquainted with practically all territories of mental life a long timebefore the founding of scientific psychology . . . because at the very begin-ning of their work there were no entirely unknown mental facts left which theycould have discovered.” 1

      There seem to be fewer surprises in psychology than in physics.

    Tags

    Annotators

  7. Jul 2022
    1. This is why, in physics today we have collaborations of thousands of people operating machines that cost billions of dollars.

      collaborations of 1000 of people operating machines that cost billions of dollars...

    1. This process serves a similar purpose in sociology to that of theblow-pipe and the balance in chemistry, or the prism and the electro¬scope in physics. That is to say, it enables the scientific worker to breakup his subject-matter, so as to isolate and examine at his leisure itsvarious component parts, and to recombine them in new and experi¬mental groupings in order to discover which sequences of events have acausal significance

      Beatrice Webb analogized the card index (or note taking using slips of paper) as serving the function of a scientific tool for sociologists the way that chemists use blow pipes and balances or physicists use the prism or electroscope. These tools all help the researcher examine small constituent parts and then situate them in other orderings to provide insight into the subject areas.

    1. they both lie in the plane "transverse"

      true by def of poynting vector

    1. you're quite unique there are maybe a few quantum physics physicists that have interest and you know but few that i think have really read nagarjuna particularly from the 00:41:08 beginning to the end of his uh you know opus magnus is his major treatise of the six we have all of those actually translated into english and you know some of them will deal more with the 00:41:20 compassion side also um so i applaud you for that

      Rovelli thus is one of the few quantum physicists to have dived so deeply into Nagarjuna's work to understand its ramifications for science, and in particular his own field.

    2. et me put it one thing do you think that uh uh it's there's anything wrong let's put it bluntly this way in in in in trying to take that from the 00:37:55 godzilla and and uh letting the thing letting this a bit of wisdom small bit of wisdom that i can get out of it uh influence the 00:38:07 rest but uh using it directly because i think that that's my that's what i think is my contribution somehow uh look there is in this uh 00:38:19 in this large uh aspect of midfield there is a there's a part of it which is definitely very relevant uh for modern physics that could be used for it and 00:38:30 um uh and from modern philosophy and you know the people in modern philosophy the people in cambridge the people in the us um not only garfield but 00:38:42 west of the others who who who are using uh a idea from the guardian in the philosophical context 00:38:57 i i think this is dialogue and i don't know if i don't know if anything could be useful in the other direction in a sense but it's uh you know i think culture is a dialogue it's a dialogue in which uh 00:39:09 in which uh uh we keep learning from from else whether it's a tradition whether it's a different school whether it is nature itself because we interact whether there's us talking to one another this constant exchange 00:39:24 that in my opinion makes the beauty of of of of culture but also uh but also the that's how we learn that's how we know that how we change

      Rovelli is trying to articulate that his focus is in the Wisdom aspect and not so much the Ethics / Compassion aspect of Nagarjuna's results, and that it is relevant for science and philosophy.

    3. let me first say how why we're here um 00:05:01 and first point out that barry and carl have never met before this is the first time you will discuss

      Title: What is Real? Nagarjuna's Middle Way A Discussion with Barry Kerzin (Doctor to HH Dalai Lama, Professor and Buddhist Monk) and Carlo Rovelli (Quantum Physicist)

  8. May 2022
    1. The clock’s methodical ticking helped bring into being the scientific mind and the scientific man. But it also took something away. As the late MIT computer scientist Joseph Weizenbaum  observed in his 1976 book, Computer Power and Human Reason: From Judgment to Calculation, the conception of the world that emerged from the widespread use of timekeeping instruments “remains an impoverished version of the older one, for it rests on a rejection of those direct experiences that formed the basis for, and indeed constituted, the old reality.” In deciding when to eat, to work, to sleep, to rise, we stopped listening to our senses and started obeying the clock.

      More effects of the clock (technology) on mankind.

      It also ushered in the idea within physics of a clockwork universe that slowly ticks away. Also the idea of a clockwork man (robot), etc.

    1. Hour Physics: What makes a good (or bad) YouTube science video

      • Influences when starting Minute Physics: xkcd, Khan Academy, RSA, RadioLab.

      Some criticism * 14:00 About Khan Academy. Like a text book; not exciting. * 15:00 About RSAnimate. Show an idea, or tell an ideal. Don't do both with one idea. Sometimes audio quality is distracting. * 17:27 About Stanford's AI course. Like Khan Academy. Like a videotaped lecture. * 18:50 About Alice & Bob. Annoying voice of Alice's character. <br /> * 24:40 About PBS & Brian Greene. Shock and Awe cliche.

      Teaching Physics * 28:16 "... why do we think about special relativity in this beautiful simple way and then teach it to first-year college students as a horrific set of equations" * Physics loves its history, "29:16 ... why would you teach physics the way it was discovered if you can teach it the way it's understood." Better focus on understanding and have a little bit of history; of the main historical events.

      Analogies in physics * 30:23 "Why do we use them [analogies] at all? And I think that this comes down to human nature and [the] fact that humans really have to understand things in relative terms. We have to put things in terms relative to something we already know and already understand. And if people are going to do it anyway it probably makes sense for you to do it; for somebody who's knowledgeable at the subject and has an idea of a good analogy to do it. Rather than let somebody come up with a super wrong analogy." * But [that said] analogies are not science. * Metanalogy[?].

      Grand Unified Theory [of science YouTube videos] * Know and respect your audience * Choose valid content. * Length appropriate for content. "Don't talk for ten minutes if you have one minute of things to say." * Use your medium to its full potential. Combine assets (video, audio, text) in a meaningful way. Make it complementary not repetitive. * Quality execution. Video should sound good, look good. Low quality is a distraction from the content of the video. * Be your own Feynman. "Be creative, be crazy, but be good [at what you do]."

      https://www.youtube.com/watch?v=_Cv5ldhxpLA

  9. Apr 2022
    1. José A. Estarelles dice: 19 abril, 2022 a las 11:42 am Buenas, Soy el traductor de esta obra de Wolfgang Smith. Tengo que decir que no es cierto que el autor desconozca o ignore la decoherencia, ni lo que algunos quieren extraer de ello, como demuestra su respuesta de 2019 al doctor McAndrew, «To Be or Not To Be an Apple» (philos-sophia.org/be-or-not-be-apple): “El famoso ‘problema de la medición’, … a pesar de las famosas pretensiones en sentido contrario, en realidad no se ha resuelto hasta ahora: ni el tour de force de la mecánica de Bohm, ni la teoría de los ‘muchos mundos’, ni la ‘decoherencia’, ni ninguna otra de sus propuestas [de la comunidad de física] ha logrado aún resolver ese dilema.” En fin, el colapso del vector de estado para nada es un “problema obsoleto”, ni “de interés histórico”. Es una cuestión plenamente vigente, por incómoda que sea para tantos. Entra Smith más en la decoherencia en los capítulos 2 y 4 de su título “The Vertical Ascent” (2020), que en gran medida se pueden consultar en la web del autor: “The Tripartite Wholeness” (philos-sophia.org/the-tripartite-wholeness) y “Lost in Math: The Particle Physics Quandary” (philos-sophia.org/particle-physics-quandary) donde, como en otro acertado comentario aquí, también se menciona a Sabine Hossenfelder. Dicho esto, y dejando a un lado el desafío que plantea la misma decoherencia para la interpretación totalista de la física cuántica, supongo que verá por qué me parece que esta reseña que hace al libro está exenta de valor crítico, aunque agradezco el interés prestado. Responder Francisco R. Villatoro dice: 19 abril, 2022 a las 1:5
      • ATENCION!!!
      • BIEN DICHO!: "[...] supongo que verá por qué me parece que esta reseña que hace al libro está exenta de valor crítico, aunque agradezco el interés prestado."
    2. Alf dice: 21 abril, 2022 a las 7:48 pm Como curiosidad en la historia de la física ¿ Desde cuando y porque ( me refiero a pruebas empíricas o formalismos matemáticos ) han dejado obsoleto a los procesos R (como colapso del vector de estado ) Responder Francisco R. Villatoro dice: 22 abril, 2022 a las 12:59 am Alf, la idea de los pioneros era que el colapso de la función de onda era un mecanismo dinámico diferente de la evolución unitaria. El formalismo de integrales de camino en mecánica cuántica y la interpretación de muchos mundos fueron cambiando la mentalidad de la mayoría de los físicos poco a poco. Durante la década de los 1970 la idea de que la única dinámica necesaria es la evolución unitaria y de que el colapso es un artificio innecesario se fue imponiendo poco a poco. A finales de la década de los 1970, los libros de texto de mecánica cuántica empezaron a omitir el problema de la medida como un problema que todo físico tuviera que conocer y el colapso dejó de mencionarse en la mayoría de dichos libros de texto, que ya solo discutían la evolución unitaria. Ya en los 1980 el colapso quedó degradado a las monografías específicas y a artículos de investigación sobre física más allá de la mecánica cuántica. A pesar de ello, la idea de que el colapso es un concepto obsoleto (además de innecesario) no se ha impuesto hasta principios del siglo XXI. Responder Alf dice: 22 abril, 2022
      • ATENCION!!!
      • @Francis: CITATION NEEDED!!! REFERENCES???
    3. joan dice: 18 abril, 2022 a las 3:17 pm que opinais de este libro: EL ENIGMA CUANTICO: ENCUENTROS ENTRE LA FISICA Y LA CONCIENCIA BRUCE ROSENBLUM FRED KUTTNER Responder Francisco R. Villatoro dice: 19 abril, 2022 a las 9:32 am Joan, el libro de Rosenblum y Kuttner parece empezar bien con su discusión de la historia que antecede a EPR y las desigualdades de Bell, pero entonces, cuando llega al nudo de la cuestión del «enigma cuántico» se hunde en la miseria; en lugar de discutir lo que se sabe sobre el asunto derrapa con el tema de la conciencia y acaba engañando al lector que esperaba una discusión sobre el «enigma cuántico» y se encuentra una discusión metafísica que no está relacionada ni con el título, ni con el resto del libro. En mi opinión, un libro bien escrito, de lectura fácil, pero muy poco recomendable para quien quiera aprender algo sobre física cuántica.
      • OK
    4. Francisco R. Villatoro dice: 15 abril, 2022 a las 9:48 am Javi, el colapso de la función de onda no existe, es un concepto obsoleto. La evolución unitaria se aplica tanto al sistema de medida como al sistema medido durante todo el proceso de la medida; cuando el sistema de medida es tan complicado que no se puede describir en pie de igualdad al sistema medido, se recurre a actualizar el estado del sistema medido tras la conclusión de la medida para hacer compatibles la evolución de ambos (esto es lo que se llama proyección del estado tras la medida). Si esta actualización se realiza de forma correcta, en futuras medidas el resultado será compatible con dicha actualización; si se realiza de forma incorrecta, habrá discrepancias, que señalarán que se ha realizado mal. No hay ningún misterio en todo esto.
      • VER respuesta de Fernando
      • Fernando dice: 16 abril, 2022 a las 5:40 am
    5. Smith es físico, matemático y filósofo
      • wikiedia.en
      • "a proponent of a new interpretation of quantum mechanics that draws heavily from medieval ontology and realism."
      • En sus libros trata mucho los temas "filosoficos"
    6. Wolfgang Smith, «El enigma cuántico. Descubriendo la clave oculta», Sekotia (2021) [188 pp.], traducido por José Antonio Estarelles
      • SEE
      • Smith W. The quantum enigma: finding the hidden key. 3rd rev. ed. Hillsdale, N.Y: Sophia Perennis; 2005. 156 p. ISBN: 978-1-59731-007-9 978-1-59731-038-3
    7. Fernando dice: 16 abril, 2022 a las 5:40 am Hola, Francis, Primero de todo, felicitarte por tu sin duda extraordinaria labor en este blog, que es digna de elogio. En segundo lugar, y ya en relación al tema aquí abordado, me ha sorprendido tu afirmación categórica acerca de la inexistencia del colapso, pues si bien es cierto que ésta es una postura sostenida por muchos físicos que trabajan en el programa de Decoherencia Cuántica, no menos cierto es que no es compartida por toda la comunidad científica. De hecho, siendo rigurosos, se trata de una corriente del pensamiento no avalada aún de manera general por los resultados matemáticos y experimentales derivados de dicho programa de investigación. Sin ir más lejos, dentro de dicho marco matemático, el colapso del sistema-aparato es aparente, pues aunque como consecuencia del entorno el operador densidad reducido del sistema-aparato acabe teniendo finalmente la forma característica de un estado mixto, el operador densidad del sistema global sistema-aparato-entorno sigue siendo el de un estado puro, por lo que el sistema global sigue estando en un estado superposición, y por ende, el observable medido sigue sin estar bien definido según el formalismo cuántico. Es más, al tomar la traza parcial sobre los estados del entorno para hacer cálculos sobre el operador densidad reducido del sistema-aparato, no estamos teniendo en cuenta la coherencia de fase global entre el sistema, el aparato y el entorno, por lo que el mecanismo de decoherencia en ningún momento afecta a dicha fase. En consecuencia, el sistema-aparato-entorno sigue en un estado superposición, no legitimándonos nada a afirmar lo contrario. Es por ello que no se puede afirmar que se haya producido un colapso real de algo, ni tampoco que la Decoherencia resuelva el problema de la lectura definida del aparato de medición. Me consta, no obstante, que el concepto de envarianza introducido por Zurek resulta lo suficientemente prometedor como para poder resolver quizás los problemas a los que conduce el citado operador densidad reducido, pero desconozco si lo ha llegado lograr. Si lo ha hecho, te agradecería me pasaras algún «paper» sobre ello para poder estar completamente actualizado. Incluso si dispusieras de tiempo y te apeteciera, estaría bien poder discutirlo privadamente de físico a físico.
      • OK: afirmacion categorica! Solo los "pro" decoherence
      • Quien eres, Fernando?
    8. Enrique dice: 17 abril, 2022 a las 5:40 pm Hola Juan, aún coincidiendo plenamente con casi todo tu planteamiento, la teoría cuántica de campos no resuelve el conocido como problema de la medida, que se ilustra, de una forma muy sencilla, con el experimento de la doble rendija: cuando no se mide por donde pasa, el electrón se comporta como onda, cuando se mide se comporta como corpúsculo. Es precisamente la decoherencia la que señala que el aparato de medida, al ser un objeto externo al sistema que hemos considerado y que además está formado por una enorme cantidad de partículas, rompe la coherencia del sistema, impidiendo que se produzca la interferencia y, por tanto, que veamos el electrón como onda.
      • NO ENTIENDO
    9. Enrique dice: 16 abril, 2022 a las 11:40 am Soy físico. Llevo más de 20 años intentando convencer a colegas y amigos de que la decoherencia es la interpretación correcta al problema de la medida en cuántica. La mayor objeción que he encontrado en los demás para aceptar esta idea no es su coherencia o lógica, sino que, ni en los libros de texto, ni en los de divulgación y en la mayoría de los artículos científicos, de lo que se habla es de colapso de la función de onda o en el mejor de los casos de pérdida de información de la matriz densidad (interpretación de Von Newman). He llegado a la conclusión de que, en los libros de divulgación se habla de colapso de la función de onda porque permite decir cosas «extrañas» sobre la física y eso vende. Por otra parte, los grandes libros de texto sobre cuántica se escribieron hace 40 años o más y fueron escritos por autores que habían estudiado las bases de la cuántica 40 años antes y por tanto, cuando el colapso de la función de onda era incuestionable. En mi opinión faltan de 10 a 20 años para veamos libros de divulgación que incluyan la decoherencia como solución al problema de la medida. Yo solo vi, en 1995, una pincelada sobre lo que era la decoherencia (apenas unas líneas) en el libro «El quark y el jaguar» del gran Murray Gell-Mann. Después de aquello, nada.
      • OK
    1. He continues by comparing open works to Quantum mechanics, and he arrives at the conclusion that open works are more like Einstein's idea of the universe, which is governed by precise laws but seems random at first. The artist in those open works arranges the work carefully so it could be re-organized by another but still keep the original voice or intent of the artist.

      Is physics open or closed?

      Could a play, made in a zettelkasten-like structure, be performed in a way so as to keep a consistent authorial voice?

      What potential applications does the idea of opera aperta have for artificial intelligence? Can it be created in such a way as to give an artificial brain a consistent "authorial voice"?

  10. Mar 2022
    1. Melvin Vopson has proposed an experiment involving particle annihilation that could prove that information has mass, and by Einstein's mass-energy equivalence, information is also energy. If true, the experiment would also show that information is one of the states of matter.

      The experiment doesn't need a particle accelerator, but instead uses slow positrons at thermal velocities.

      Melvin Vopson is an information theory researcher at the University of Portsmouth in the United Kingdom.

      A proof that information has mass (or is energy) may explain the idea of dark matter. Vopson's rough calculations indicate that 10^93 bits of information would explain all of the “missing” dark matter.

      Vopson's 2022 AIP Advances paper would indicate that the smallest theoretical size of digital bits, presuming they are stable and exist on their own would become the smallest known building blocks of matter.

      The width of digital bits today is between ten and 30 nanometers. Smaller physical bits could mean more densely packed storage devices.


      Vopson proposes that a positron-electron annihilation should produce energy equivalent to the masses of the two particles. It should also produce an extra dash of energy: two infrared, low-energy photons of a specific wavelength (predicted to be about 50 microns), as a direct result of erasing the information content of the particles.

      The mass-energy-information equivalence principle Vopson proposed in his 2019 AIP Advances paper assumes that a digital information bit is not just physical, but has a “finite and quantifiable mass while it stores information.” This very small mass is 3.19 × 1038 kilograms at room temperature.

      For example, if you erase one terabyte of data from a storage device, it would decrease in mass by 2.5 × 1025 kilograms, a mass so small that it can only be compared to the mass of a proton, which is about 1.67 × 1027 kilograms.

      In 1961, Rolf Landauer first proposed the idea that a bit is physical and has a well-defined energy. When one bit of information is erased, the bit dissipates a measurable amount of energy.

    1. First, what do I mean by meta-stable? It’s in reference to an article by Scott H Young - 7 Rules for Staying Productive Long-Term. In it, Scott describes a concept in physics where something is stable but small perturbations can cause it to break, and not able to go back to its starting position after a small push. The example he gives is a pendulum, perfectly balanced at the top; when pushed will not return to its starting point. Contrast this with a pendulum’s other stable point, the bottom. When pushed, it’ll return to that starting point easily.

      Something is meta-stable if small perturbations won't cause it to break or be able to go back to its starting point.

      example: pendulum

    1. Ryan Usher says: January 22, 2022 at 6:19 pm “…I don’t at all understand why Quanta chose to cover this.” This is something I find myself wondering as well, and it’s not the first time Quanta has fallen prey to this kind of hype–and I characterize it in that way to be generous to Quanta in the face of my cynicism. So I decided to waste a couple of hours to come up with the following:
      • SEE
    1. gravitational míreming woh* This text was recognized by the built-in Ocrad engine. A better transcription may be attained by right clicking on the selection and changing the OCR engine to "Tesseract" (under the "Language" menu). This message can be removed in the future by unchecking "OCR Disclaimer" (under the Options menu). More info: http://projectnaptha.com/ocrad

      Gravitational microlensing

      • gravitational wave approaching the earth is interrupted by blackhole, signal gets modified
  11. Feb 2022
  12. Dec 2021
    1. gravity on the poles in a bit larger
      • BEWARE!
      • is not "gravity"; it is the RESULTING "acceleration" on the massive (IMPORTANT) object: gravity + rotation
      • BESIDES: there are 2 factors:
        • distance to center: pole < equator
        • rotation: pole=0 < equator
    1. Physics Hamiltonian for the zeros of the Riemann Zeta function (2016) General Relativity and Cosmology: Unsolved Questions and Future Directions (2016) There are no particles, there are only fields (2012) Would Bohr be born if Bohm were born before Born? (2007) The holographic solution - why general relativity must be understood in terms of strings (2004) Measurement of subpicosecond time intervals between two photons by Interference (1987) Bertlmann’s socks and the nature of reality (1981) More is different (1972) On the Einstein Podolsky Rosen Paradox (1964) Deterministic Nonperiodic Flow (1962) There's Plenty of Room at the Bottom (1959) Forms of Relativistic Dynamics (1949) What is life? (1944) Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? (1935) Possible Existence of a Neutron (1932) On the electrodynamics of moving bodies (1905)

      see

  13. Nov 2021
    1. “Because physicists started out with the imaginary, unstable cube as their model instead of the real-world stable tetrahedron, they got into all these imaginary numbers and other complicated and completely unnecessary mathematics. It would be so much simpler if they started out with the tetrahedron, which is nature’s best structure, the simplest structural system in Universe.

      (Just as an aside, to remember later when you’re studying physics in school, I want to point out that the tetrahedron is also equivalent to the quantum unit of physics, and to the electron.)”

  14. Oct 2021
    1. The spiritual vision of the Bauhaus was a faith in people’s ability to transform society for good by breaking down divisions and working together toward a common purpose.

      Originally published on Medium on August 29, 2019.

    1. General relativity implies that information gets destroyed; quantum theory says it’s preserved. Hence the paradox.

      Isn't this an example of the law of the excluded middle? If LoEM doesn't exist (in Gisin's theory), then could there be information that isn't either created or destroyed?

  15. Sep 2021
    1. In thermodynamics, a diathermal wall between two thermodynamic systems allows heat transfer but do not allow transfer of matter across it
  16. Aug 2021
  17. Jul 2021
    1. We may assume that Anaximander somehow had to defend his bold theory of the free-floating, unsupported earth against the obvious question of why the earth does not fall. Aristotle’s version of Anaximander’s argument runs like this: “But there are some who say that it (namely, the earth) stays where it is because of equality, such as among the ancients Anaximander. For that which is situated in the center and at equal distances from the extremes, has no inclination whatsoever to move up rather than down or sideways; and since it is impossible to move in opposite directions at the same time, it necessarily stays where it is.” (De caelo 295b10ff., DK 12A26) Many authors have pointed to the fact that this is the first known example of an argument that is based on the principle of sufficient reason (the principle that for everything which occurs there is a reason or explanation for why it occurs, and why this way rather than that).

      principle of sufficient reason

      : for everything which occurs there is a reason or explanation for why it occurs, and why this way rather than that

      The first example in Western culture is that of Anaximander explaining why the Earth does not fall.

    2. These observations were made with the naked eye and with the help of some simple instruments as the gnomon. The Babylonians, in particular, were rather advanced observers. Archeologists have found an abundance of cuneiform texts on astronomical observations. In contrast, there exists only one report of an observation made by Anaximander, which concerns the date on which the Pleiades set in the morning. This is no coincidence, for Anaximander’s merits do not lie in the field of observational astronomy, unlike the Babylonians and the Egyptians, but in that of speculative astronomy. We may discern three of his astronomical speculations: (1) that the celestial bodies make full circles and pass also beneath the earth, (2) that the earth floats free and unsupported in space, and (3) that the celestial bodies lie behind one another. Notwithstanding their rather primitive outlook, these three propositions, which make up the core of Anaximander’s astronomy, meant a tremendous jump forward and constitute the origin of our Western concept of the universe.

      Anaximander practiced speculative astronomy instead of just observational astronomy and in so doing, he dramatically changed the cosmological outlook of Western culture.

  18. Jun 2021
    1. The Internet, an immeasurably powerful computing system, is subsuming most of our other intellectual technologies. It’s becoming our map and our clock, our printing press and our typewriter, our calculator and our telephone, and our radio and TV.

      An example of technological progress subsuming broader things and abstracting them into something larger.

      Most good mathematical and physical theories exhibit this sort of behaviour. Cross reference Simon Singh's The Big Bang.

  19. May 2021
    1. The largest collection of Isaac Newton's papers has gone digital, committing to open-access posterity the works of one of history's greatest scientist. Among the works shared online by the Cambridge Digital Library are Newton's own annotated copy of Principia Mathematica and the 'Waste Book,' the notebook in which a young Newton worked out the principles of calculus.

      I've annotated something about Isaac Newton's Waste Book for calculus before (possibly in Cambridge's Digital Library itself, but just in case, I'm making a note of it here again so it doesn't get lost.

      In my own practice, I occasionally use small notebooks to write temporary notes into before transferring them into other digital forms. I generally don't throw them away, but they're essentially waste books in a sense.

  20. Apr 2021
    1. It compels us to understand that not every acceleration results from a universal force and this is the essential idea of the first law.

      the conclusion

  21. Feb 2021
    1. Say, for instance, a hypothetical self-driving car is sold as being the safest on the market. One of the factors that makes it safer is that it “knows” when a big truck pulls up along its left side and automatically moves itself three inches to the right while still remaining in its own lane. But what if a cyclist or motorcycle happens to be pulling up on the right at the same time and is thus killed because of this safety feature?

      I think that an algorithm that's "smart" enough to move away from a truck is also "smart" enough to know that it cannot physically occupy the same space as the motorcycle.

  22. Dec 2020
  23. Oct 2020
    1. Quantum: Einstein, Bohr, and the Great Debate about the Nature of Reality Illustrated Edition by {"isAjaxComplete_B0032HW9M0":"0","isAjaxInProgress_B0032HW9M0":"0"} Manjit Kumar (Author) › Visit Amazon's Manjit Kumar Page Find all the books, read about the author, and more. See search results for this author Are you an author? Learn about Author Central Manjit Kumar (Author)
    1. Physics of the Impossible: A Scientific Exploration of the World of Phasers, Force Fields, Teleportation and Time Travel by {"isAjaxComplete_B000ARDFYQ":"0","isAjaxInProgress_B000ARDFYQ":"0"} Michio Kaku (Author) › Visit Amazon's Michio Kaku Page Find all the books, read about the author, and more. See search results for this author Are you an author? Learn about Author Central Michio Kaku (Author)
    1. Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100 Paperback – Illustrated, February 21, 2012 by {"isAjaxComplete_B000ARDFYQ":"0","isAjaxInProgress_B000ARDFYQ":"0"} Michio Kaku (Author) › Visit Amazon's Michio Kaku Page Find all the books, read about the author, and more. See search results for this author Are you an author? Learn about Author Central Michio Kaku (Author)
    1. Nevertheless, physicists continue to select theories based on the same three criteria of beauty: simplicity, naturalness, and elegance.
    2. I think it’s time we take a lesson from the history of science. Beauty does not have a good track record as a guide for theory-development.
    3. History has a second lesson. Even though beauty was arguably a strong personal motivator for many physicists, the problems that led to breakthroughs were not merely aesthetic misgivings – they were mathematical contradictions. Einstein, for example, abolished absolute time because it was in contradiction with Maxwell’s electromagnetism, thereby creating special relativity. He then resolved the conflict between special relativity and Newtonian gravity, which gave him general relativity. Dirac later removed the disagreement between special relativity and quantum mechanics, which led to the development of the quantum field theories which we still use in particle physics today.
    4. My conclusion from this long line of null results is that when physics tries to rectify a perceived lack of beauty, we waste time on problems that aren’t really problems. Physicists must rethink their methods, now – before we start discussing whether the world needs a next larger particle collider or yet another dark matter search.

      $$Insert LaTeX$$

    1. In some sense, by studying one model deeply enough, we can study them all.

      This may be where math like category theory is particularly powerful as a map between these different areas which are really the same (isomorphic).

    1. Their findings indicate that the set of all quantum field theories forms a unique mathematical structure, one that does indeed pull itself up by its own bootstraps, which means it can be understood on its own terms.

      What kind of structure? Group? Ring? Other?