Experimental Search for Quantum Gravity PDF
Preview Experimental Search for Quantum Gravity
FIAS Interdisciplinary Science Series Sabine Hossenfelder Editor Experimental Search for Quantum Gravity FIAS Interdisciplinary Science Series Editor-in-chief Walter Greiner, Frankfurt am Main, Germany Editorial Board Ernst Bamberg, Frankfurt am Main, Germany Marc Thilo Figge, Jena, Germany Thomas Haberer, Heidelberg, Germany Volker Lindenstruth, Frankfurt am Main, Germany Joachim Reinhardt, Frankfurt, Germany Klaus Schulten, Urbana, USA Wolf Singer, Frankfurt am Main, Germany Horst Stöcker, Darmstadt, Germany More information about this series at http://www.springer.com/series/10781 Sabine Hossenfelder Editor Experimental Search for Quantum Gravity 123 Editor SabineHossenfelder FrankfurtInstitute for AdvancedStudies (FIAS) Frankfurtam Main Germany FIAS Interdisciplinary ScienceSeries ISBN978-3-319-64536-0 ISBN978-3-319-64537-7 (eBook) https://doi.org/10.1007/978-3-319-64537-7 LibraryofCongressControlNumber:2017948197 ©SpringerInternationalPublishingAG2018 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. 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Printedonacid-freepaper ThisSpringerimprintispublishedbySpringerNature TheregisteredcompanyisSpringerInternationalPublishingAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland Preface Ifyouhavegoodeyes,thesmallestobjectsyoucanmakeoutareaboutatenthofa millimeter, roughly the width of a human hair. Add technology, and the smallest structures we have measured so far are approximately 10−19 m, that is, the wave- lengthoftheprotonscollidedattheLHC.Ithastakenusabout400yearsfromthe invention of the microscope to the construction of the LHC—400 years to cross 15 orders of magnitude. Quantum effects of gravity are estimated to become relevant on distance scales ofapproximately10−35m,knownasthePlancklength.Thatisanother16ordersof magnitudetogo.Itmakesyouwonderwhetheritispossibleatallorwhetherallthe effort to find a quantum theory of gravity is just idle speculation. Iamoptimistic.Thehistoryofscienceisfullwithpeoplewhothoughtthingsto beimpossiblethathavemeanwhilebeendone:measuringthelightdeflectiononthe sun, heavier-than-airflying machines, detecting gravitational waves. Hence, I don’t think it is impossible to experimentally test quantum gravity. Maybe it will take some decades,ormaybe itwill takesome centuries—butifonlywekeeppushing, one day we will measure quantum gravitational effects. Not by directly crossing these 15 orders of magnitude, I believe, but instead by indirect detections at lower energies. From nothing comes nothing though. If we do not think about how quantum gravitationaleffectscanlooklikeandwheretheymightshowup,wewillcertainly never find them. But fueling my optimism is the steadily increasing interest in the phenomenologyofquantumgravity,theresearchareadedicatedtostudyinghowto best find evidence for quantum gravitational effects. Since there is not any one agreed-upon theory for quantum gravity, existing effortstofindobservablephenomenafocusonfindingwaystotestgeneralfeatures of the theory, properties that have been found in several different approaches to quantumgravity.Quantumfluctuationsofspace-time,forexample,orthepresence of a “minimal length” would impose a fundamental resolution limit. Such effects can be quantified in mathematical models, which can then be used to estimate the strength of the effects and thus to find out which experiments are most promising. v vi Preface Thisvolumecollectssomerecentdevelopmentsinthefieldofphenomenological quantum gravity that were subject of the recent conference on “Experimental SearchforQuantumGravity.”ThismeetingtookplaceattheFrankfurtInstituteof Advanced Studies (FIAS) in September 2016 as part of the first Giersch Symposion. Frankfurt am Main, Germany Sabine Hossenfelder June 2017 Contents Astroparticle Physics Connections to the Quantum Gravity Problem... .... .... ..... .... .... .... .... .... ..... .... 1 Matthias Lorentz The Search for a Tiny Hint from Quantum Gravity in the Cosmic Relic Radiation ..... .... .... .... .... .... ..... .... 9 David Brizuela and Manuel Krämer Superfluid Helium: The Volovik Lessons .... .... .... .... ..... .... 15 Tim Lappe On the Paradigms of Quantum Gravity 2016. .... .... .... ..... .... 21 Fabian Müller On the Measurement of the Speed of Light in a Cavity. .... ..... .... 29 Fabienne Schneiter Neutrino: The Elusive Particle Bringing us Closer to the World of Quantum Gravity.. .... .... .... .... .... ..... .... 37 Giacomo D’Amico Gravitational Waves: The “Sound” of the Universe.... .... ..... .... 43 José Manuel Carmona Essay on Planck Star Phenomenology... .... .... .... .... ..... .... 49 Alexander Maximilian Eller Essay About Gravitational Measurements at Small Distances..... .... 55 Helena Schmidt Return on Investment in Quantum-Gravity Research .. .... ..... .... 61 Giovanni Amelino-Camelia Semiclassical Gravity: A Testable Theory of Quantum Gravity ... .... 69 Sabina Scully vii viii Contents Quantum Gravity Deformations ... .... .... .... .... .... ..... .... 77 Antonia Micol Frassino General Relativity, Black Holes and Planck Stars . .... .... ..... .... 85 Matteo Trudu Spacetime Structure: Analogy in Condensed Matter and Quantum Information... ..... .... .... .... .... .... ..... .... 91 Martin Seltmann Experimental Search for Quantum Gravity Using Cosmology .... .... 105 Manon Bischoff and Vincent Vennin The Cosmological Constant and Its Problems: A Review of Gravitational Aether.. .... ..... .... .... .... .... .... ..... .... 109 Michael Florian Wondrak Astroparticle Physics Connections to the Quantum Gravity Problem MatthiasLorentz Introduction The Universe can be used as a formidable laboratory for high-energy physics. In contrasttoparticlephysicsatcolliderswheretheexperimentalenvironmentiswell controlled, astroparticle physics deals with elementary particles in “natural” envi- ronmentswherediverseastrophysicalprocessesareatplay.Whilethiscanintroduce anadditionallevelofcomplexityinthephysicalinterpretationofdata,theparticle energiesachievablebycosmicacceleratorsarebeyondthecapabilitiesofman-made accelerators(seeFig.1)andthesehigh-energyparticlespropagateovercosmological distances,offeringuniqueopportunitiestoaddressfundamentalphysicsaspects. Thequestionofquantumgravity(QG)remainsunanswered,asnoconsistentthe- ory combining quantum field theory and general relativity have been found so far. TheoriesofQGhavebeendevelopedbasedonmathematicalconsistencyarguments butthelackofobservationalevidenceduetotheextremelysmallexpectedeffectsren- dersverydifficulttoproperlytestandguidesuchspeculativetheories.Thissituationis changingasmoreandmoreeffortsareputintodevelopingaphenomenologyofQG, searching for viable experimental tests in various fields, and astroparticle physics offers many attractive possibilities. We briefly present here selected astroparticle aspectsrelevantintheexperimentalsearchforQGmainlyfocusedonPlanck-scale tests of Lorentz symmetry, in the perspective of current and future experimental facilities. B M.Lorentz ( ) Irfu,CEASaclay,91191Gif-sur-Yvette,France e-mail:[email protected] ©SpringerInternationalPublishingAG2018 1 S.Hossenfelder(ed.),ExperimentalSearchforQuantumGravity, FIASInterdisciplinaryScienceSeries,https://doi.org/10.1007/978-3-319-64537-7_1
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