PoS(LHCP2016)047 http://pos.sissa.it/ ∗ Speaker. I give my perspective on promising directions for high energy physics in coming years. ∗ Copyright owned by the author(s) under the terms of the Creative Commons c Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). Fourth Annual Large Hadron Collider Physics 13-18 June 2016 Lund, Sweden [email protected] Frank Wilczek Center for Theoretical Physics, MIT, CambridgeDepartment MA of 02139 Physics, USA Stockholm University, StockholmDepartment Sweden of Physics and Origins Project,Wilczek Arizona Quantum State Center, Zhejiang University, Tempe University AZ of 25287 Technology, Hangzhou USA 310023 China Theory Vision, LHCP 2016 PoS(LHCP2016)047 ) 1 ( U × ) 2 ( Frank Wilczek SU × ) 3 ( SU the strange quark mass, and the strong s m ] 1 1 of up and down quark masses, d m 2 + u m Comparison of theory and experiment in the calculation of low-lying hadron masses. Input Consider, for example, the direct numerical solution of QCD. Here there are no uncontrolled 1. Our standard model, or core theory, understood to consist of the approximations, no perturbation theory, noparameters, cutoff, inserted and into no a roomwon’t highly account for for constrained fudge-factors. the theory incredible Acertainly of wealth handful appears of extraordinary of that measured they symmetry, phenomena do. either in will the strong or interaction. And it gauge theory of stronggravity and – electroweak the interactions, gauge togethera theory with firm of foundation minimally local for coupled Lorentz chemistry,and invariance Einstein astrophysics, fulfills – and the is all great a practical reductionistmathematical glorious forms understanding program achievement. of of of the engineering. interactions understanding It among the provides It a physical few justifies basic world building-blocks. based on precise Figure 1: parameters are the average coupling constant, which determines the overall mass scale. [ Theory Vision 1. The Standard Model: Glory and Discontents PoS(LHCP2016)047 : 2 × × × c ) ) ) ]. / 2 3 2 2 ( ( ( E = SU SU SU m × ) 3 Frank Wilczek ( – do a brilliant ) SU 10 ( → ) SO 5 ( practically begs to be em- SU ) 1 ( U × ) 2 ( , and especially ) 5 SU ( × ) SU 3 ( 2 SU . ) 1 ( hypercharge quantum numbers we need to assign to those U Y , needed to give a smooth theory of neutrino masses, there are ) N × 1 ( ) 2 U ( SU × ) 3 ( SU , shows how the full symmetry of fundamental equations can be hidden in their → Q ) into a (technically) simple structure – ) ) 1 10 ( 1 ( ( U U SO → × or ) Y An important test for the hypothetical expanded symmetries is whether they act naturally on It is remarkable that the simplest candidate symmetries to unify the product groups of (Though I won’t develop it here, I should mention that one can constrain the hypercharges Among the rest, we see here the origin of (most) mass in pure energy, according to If the LHC project does nothing other than confirm2. the standard Yet model, that it would will be have a made disappointing a result. For all its virtues, the standard model does not There are also important phenomena, notably in cosmology, which the standard model does 3. There are, of course, many directions of theoretical exploration around the issues in funda- 4. The product gauge symmetry structure 2 ) ) ( 1 1 ( ( job of organizing the fermion multiplets and explaining those funny fractional hypercharges [ SU quarks and leptons. Indeed, anotherit “imperfection” classifies of the quarks symmetry and ofallow leptons the for standard the into model right-handed several neutrino is unrelated that multiplets, even within one family. If we six (if not, five).multiplets Moreover are the funny fractions, determined phenomenologically. in an alternative way, by demanding anomaly cancellation. That approach does not address the low-energy solutions, by theSlightly more influence elaborate versions of of the same cosmic mechanism can fields implement or condensations (Higgs mechanism). bedded into a larger, encompassing symmetry. The electroweak theory, which breaks profound contribution to science and culture. have the look of afalling finished into product. several lopsided multiplets. Its For symmetry unknownthere structure reasons, is these is the multiplets imperfect, Higgs are triplicated. with doublet, which Then quarksaccommodate by and quark contrast and leptons comes lepton in masses singly, and and mixings, whose are many poorly couplings, constrained fixed theoretically. to not address. The astronomical darknone matter, of in the standard particular, model’s appears particles has to theabout be right promising properties. a but vague Also, gas fundamental we of would physics-based relic like scenariosasymmetry be particles, for and more the but specific of origin inflation, of matter-antimatter andcosmological to constant). get better insight into the nature of the darkmental energy physics (Einstein’s that inspire theselective. LHC program. I will In mainly this focus shortwith on “visionary” that a talk assessment, pair but I of I will ideas hope haveto that you to determine. will I be agree think very that deserve they to are be ideas true. whose truth-value You it may is not important agree 2. Unification Quantum Numbers Theory Vision Using massless gluons and (almost) masslessprotons quarks as and our neutrons. ingredients, we account for the mass of U U PoS(LHCP2016)047 , R N u . 2 Frank Wilczek ], and I will not 3 3 ). Each of those particles can have a left-handed (L) or ν ), is indicated by a numerical subscript. Y and so forth. The far-left table shows all possible assignments of full or empty circles u This figure shows how the rather untidy organization of fundamental particles, according to our − The black column of symbols in the left-hand panel shows up (u) and down (d) quarks, the The right hand panel shows how the observed, scattered pattern of particles can be deduced We get to the right side of the table panel by invoking the rule that adding equal amounts of all I reviewed the details of quantum number unification recently elsewhere [ right-handed (R) helicity; the left-handedplays particles six are distinct organized entities. inaccount doublets, The for their so left strong, the side weak, column and ofinteraction, electromagnetic dis- the interactions. respond table Gluons, to which displays three mediate the the strongweak strong properties “color” interactions, of charges, which those only here entities act indicatedhere upon that by indicated left-handed red, as particles, green, yellow respond and and to purple.tric blue. two charge. Electromagnetism weak The is color incorporated On charges, through thehypercharge couplings ( left to elec- side of the panel, the average charge within each entity, also called its electron (e), and the electron neutrino ( from a unified template, derivedgives from the higher names symmetry. of the Thein particles. far-right the column Here, earlier of everything has the description left-handed panel are helicity; again now right-handed represented particles through their left-handed antiparticles, so that repeat the mathematical analysis here. Let us proceed directly to the summarizing Figure Figure 2: present day core theories ofexplained the by, strong, a weak, highly and symmetric electromagnetic unified theory. interactions falls neatly into, and can be becomes of strong and weak colors,circle subject is to interpreted as the a constraint positive half-unit thathalf-unit. of the the The corresponding number hypercharge charge, values, of an which empty full appear circleweak in circles as the and a is middle negative strong even. column, color are charges A now according full generated to from the the formula on top. Theory Vision unification of couplings, which I’ll discuss momentarily.nearly Nor so does it neatly: explain the In multiplet structure particular, it does not predict the existence of the right-handed neutrino which plays a central role in the theory of neutrino masses.) PoS(LHCP2016)047 , ) 10 ( ]. We 4 SO or consistency ) Frank Wilczek 5 ( ], and I will not 3 SU physical occurs through a big conden- about the spectrum of virtual ) 1 ( H U × ) , we have three inputs – the observed 2 couplings evolve differently. ( ) H 1 SU ( × U ) × 3 ( ) 4 2 ( SU SU → × G ) 3 ( is to take into account vacuum polarization from all the presently SU . min H must be equal. As observed, of course, they are not. But the two great ) 1 ( U × ) 2 ( SU . 3 × ) Again, I reviewed the details of coupling unification recently elsewhere [ 6. There are several ways to motivate the additional hypothesis of supersymmetry. Here I’ll The minimal hypothesis Let us pause to consider, in broad terms, what we can expect from this sort of calculation. 5. The glory of local (gauge) symmetry, however, is that it controls not only bookkeeping, 3 ( mention one that is rarely (ifapt, ever) discussed, in but the which context I of find unification. profoundly attractive. It is especially sation, at a high mass scale.large In mass the scales, symmetric there theory, appropriate waslower to only mass the one scale. description unified To of get coupling. processes to at theenergy, But unified taking we coupling, into make we account our must evolve vacuum observations thesymmetry at polarization. observed is a couplings violated, Note up much so to that the high three throughout that evolution the unified particles we need to include instrength, the vacuum and polarization. the Our output scale shouldcouplings of be – the and unification. unified two coupling outputs – Forcondition. the any scale If given and coupling the at calculationcore unification. works, of So the we there will standard will be model haveconditions, a by reduced concerning consistency one, the the from value number of three ofthose the to momentarily. free unification two. scale, parameters There which in are are the quite additional significant. I’ll come to known particles, and no others.titative Doing failure, that, as we illustrated find in a the suggestive panel approach on to the equality, left. but aSupersymmetry quan- Our input will be the observed couplings, plus some hypothesis can imagine that the symmetry breaking repeat the mathematical analysis here.Figure Instead, let us proceed directly to the iconic summarizing but also dynamics. For a simple (in the technical sense) gauge group such as Theory Vision the strong color charges, orquantum equal numbers, amounts is of invisible to all the the strongscheme weak or on weak color interactions. the charges, That left corresponding allows side to us ofin singlet to full the change units. the table color Remarkably, into the that resulting onthe strong the and quantum right weak numbers colors, side. of and Note the the thatthe hypercharges, entries neatly opposite the the match color color right-hand charges charges panel, and are i.e. hypercharges now from reality. their (Note corresponding that particles.) antiparticlesCoupling have Strengths symmetry predicts all the couplings ofThus the unification gauge predicts bosons, relationships up amongsically to the a – strong, single up overall weak, to coupling and the constant. SU hypercharge group-theoretic couplings. task of Ba- normalizationdynamical – lessons it of predicts the that standard model the(Higgs – mechanism), three namely and couplings symmetry running for breaking of through couplings field (asymptotic condensation freedom) – suggest a way out [ PoS(LHCP2016)047 in N G together N . Here the , we expect G 1 E Frank Wilczek that naturally appears with π GeV (2.1) 18 10 × 4 . 2 ≈ 5 N 5 G ¯ hc π 8 . 2 s ) GeV is significantly, but not grotesquely, smaller than the = 16 Planck E 10 / Planck E × E ( 2 of low-energy supersymmetry as input, our modified coupling strength ≈ susy H unification E ] succeeds quantitatively. 5 The equality of coupling strengths at high energy, suggested by theories of unification, is sug- . On the face of it, Planck units set the scale for effects of quantum gravity; thus when c , ¯ h We have quoted the so-called rationalized Planck scale, including the factor 8 The Planck energy 7. Supersymmetry requires that we add new particles. Let us suppose that we do this in Wave-particle duality, a central achievement of quantum theory, allows us to treat light and Our scale 1 ]. 3 is another famous energyconstruction scale is that simple dimensional can analysis, be based on constructed Newton’s gravitational from constant fundamental constants a minimal way, addingWith as that few hypothesis particles as possible, and keeping their mass as low as possible. “material”, or ultimately force and substance,ment in of a single unified fashion. photons The orbreaks quantum-mechanical single down, treat- electrons, however, when for we example, movefind is beyond a essentially division single of identical. particles, the to world Thatmetrically into consider unification opposed. bosons assemblies. and Supersymmetry, fermions, however, There allows whose we us quantum totypes, statistical transform and properties between thereby are those completes dia- two the statistical work of force-substance unification. unification [ with we consider basic (technically: “hard”) processes whose typical energies are of order Planck scale. This means that at the unification scalethe Lagrangian the of general strength relativity. of gravity, heuristically and Figure 3: gested, but not achieved,hypothesis of by supersymmetry, minimal one achieves extension good[ of quantitative agreement. known For interactions more (left detailed discussion, panel). see With the additional Theory Vision gravitational effects of order PoS(LHCP2016)047 (2.2) GeV the 16 10 Frank Wilczek × 2 ]. ∼ 10 unified E is crucial for explaining the 4 unification − E 10 ∼ 2 ) for the other interactions. The relative smallness 6 2 Planck − E / 10 ∼ , or even a bit less. While this does not meet the challenge 4 π times smaller than any of the other forces. Again, however, 10 4 unification / 42 E ∼ 2 5 ( g 10 evidence for the hypothesis of low-energy supersymmetry. We’ve ∼ is reduced to 42 quantitative 8. Unfortunately, however, this circle of ideas does not yield a sharp estimate for the mass of 9. Few aspects of experience are as striking as the distinction between past and future. Yet for To me, the results of §5, supplemented by the discussion of §6 and §7, provide powerful, On the other hand, it seems to me remarkable that the comparison comes so close. A classic By expanding our theory, unification along the lines we have been discussing brings in addi- the new particles. The vacuumonly logarithmically polarization on effects, their through mass values. which Whilefor we the have the best fits “seen” gluinos, seem them, to and depend indicatewhile less a few the for TeV mass squarks the scale and otherThough sleptons gauginos, the are an LHC very has order a weakly of greatbe constrained, magnitude opportunity definitive. and to heavier discover could is the be not new particles, considerably excluded; a heavier. negative result would not 3. T Symmetry and Its Violation the first three centuries of recognizablypeared modern that physics, the ever since fundamental the laws Scientific knewor Revolution, no simply it such T. ap- Newton’s distinction. theories of They dynamics obeyedelectrodynamics, and time-reversal and gravity, symmetry, Einstein’s all modifications experiments thereof, in quantum ture. particle As and a nuclear result physics T appeared wasown to taken right. display for granted, that and fea- came to be regarded as a fundamental principle in its “seen” the effects of itsthem particles, as in real their particles. virtual form. Now we look for LHC to start producing if circumstantial, to be compared with the strength discrepant factor 10 proper comparison requires that we specify the energythe scale strength at of which gravity, the in comparison general is made. relativity,when depends Since on observed energy with directly, it high-energy appears hugely probes. enhanced At the scale of unification challenge in fundamental physics is togravity, understand compared the grotesque to smallness other of interactions, thethe as observed gravitational force it interaction of operates is between fundamental particles . Famously, tional interactions. The twosmall classic neutrino predictions masses, for leading “beyond to thevindicated; neutrino standard the oscillations, second model” and not interactions proton yet. decay. are In The both first cases, has the been large been scale Theory Vision semi-quantitatively, is of order of gravity, thus estimated, whichour is neglect of of course quantum gravity further in accentuated the at preceding lower calculations energies, may be suggests justified. that fully, it is a big step in the right direction. smallness of the new effects.emphasizing For the an phenomenological authoritative issues, review with of many these further and references, other see aspects [ of unification, PoS(LHCP2016)047 = θ (3.1) their duals. Frank Wilczek µν a ˜ G a B ~ · a E ~ . This is a mockery of dimensional 2 θ ]. Their result presented a tremendous 10 π 2 s 6 − 8 is an index parameterizing the adjoint 8 g 10 = ,..., . 1 . Those quarks were later discovered. The t | µν a , θ = b | G 7 a are gluon field strengths and the µν a µν a ˜ G G 2 θ π 2 s g 32 = L is a dimensionless parameter. ∆ coupling constant, θ ) a fundamental principle. . 3 a ( ), is manifestly local, relativistically invariant, and gauge invariant. Fur- B ~ not , a 3.1 SU ]. Their theory relied on the existence of new particles, not then discovered: 7 E ~ is the strong s g Yet, as we shall soon discuss, all presently available observations are consistent with 11. Strong T symmetry remains problematic, however. As I’ve emphasized, the interactions allowed by the standard model are constrained by pow- That situation changed in 1964, when a team led by James Cronin and Valentine Fitch, working Progress in fundamental physics over a broad front, culminating in the establishment of to- 10. Weak T-violation was elucidated in a brilliant paper by Makoto Kobayashi and Toshihide This term, Eqn. ( thermore its mass dimensioninteraction is can be 4, included and consistently, without sinceory, upsetting the which QCD good is is ultraviolet behavior necessary asymptotically ofT-violation. the to free, the- insure one its expects existence. that this Its existence opens up the possibility of strong Here 0. Existing experimental bounds correspond to what we call today the bottom and top quarks erful general principles of quantumstraints, mechanics, every possible relativity, interaction and has gauge been measured symmetry. toexception Given occur is – those a with con- possible one prominent interaction exception. amongby The the the color Lagrangian gluon density fields, the so-called theta term, governed Kobayashi-Maskawa theory explains the original Cronin-Fitchup observation, measurements and of also many weak follow- interaction processes. representation (octet of color gluons), the analysis, and is often said to be “unnatural”. at Brookhaven National Laboratory, discovered a subtle T-violating(unstable effect particles in the produced decay at of high-energy K mesons accelerators) [ day’s standard model, essentially in its modernized form, that greatly general illuminated principles this of issue. special Physicistspowerfully relativity, quantum real- constrain mechanics, the and gauge possible symmetry interactions together tually of fail, particles. of course, (Those but general theyvery principles were rigorous might key testing. to even- Until formulating proven the otherwise,more standard most model, fundamental physicists and than accept they them T.) have as When survived gauge working applied hypotheses, bosons, to the the graviton, known andare build-blocks the of exactly Higgs matter two particle – possible – quarks, kindsT-violation, those since leptons, of they general T-violating are principle interactions. mainly determine associated that with We the there might weak call and them strong interaction, weak respectively. Maskawa, and in strong 1973 [ Theory Vision challenge to theoretical physics: To understandstances, why T given that works extremely it accurately is in most circum- In the second equality we re-writeand magnetic this fields expression in non-relativistic form, using the color electric PoS(LHCP2016)047 15 − ]. It (3.4) (3.2) 11 , but only θ Frank Wilczek parameter and to probe denotes “electron”; there θ e E ~ · cm cm cm (3.3) | S S ~ ~ | − − − e e e e d 10 25 28 26 − − ] using accelerator techniques similar to those − − − or less – is impressive. More precise reasoning 9 10 10 10 10 10 = × 8 − × × × 3 E ~ 9 2 6 · . e | ~ d < < < θ arise from measurements of fundamental electric dipole | − | | | θ n cm, and it contains several quarks whose charges are robust Tl d Hg | = 205 14 199 d − d | H | ] leads to the quantitative bound 8 ] 13. To ascribe the appearance of such an extraordinarily small number in the fundamental laws Several speculative proposals have been put forward to explain the smallness of 12. At present the best bounds on Since the size of the neutron, as measured either by its Compton wavelength or its charge (Note that the familiar electric dipole moments of elementary chemistry involve transition ma- There is a long history of attempts to measure fundamental electric dipole moments, going There are promising new ideas to greatly improve the accuracy of such measurements, specif- 8 involves postulating a new kind of symmetry, called Peccei-Quinn (PQ) symmetry. of nature to coincidence is a poorand response. that It we seems have likely that been Nature given is an trying opportunity to to tell us expand something, our understanding of fundamentals. Axions one has been widely accepted. Its basic idea is due to Roberto Peccei and Helen Quinn [ that have been successful in givingThese precise are measurements of extremely the important muon’s magnetic measurements, dipole both moment. the pin down the radius, is in the neighborhood of 10 Theory Vision Electric Dipole Moments moments. The electric dipoleterm moment (Hamiltonian) of the electron appears as the coefficient of an interaction governing the coupling of its spin to an electric field. Here the subscript other possible sources of T violations, such as arise abundantly in low-energy supersymmetry. fractions of e, naive dimensional analysis woulde-cm. suggest a The value mismatch more – in a the suppression neighborhood factor of of 10 10 trix elements. They are appropriatecan to be use neglected, when which the is energy often separation the between case the in states practical involved work.) back to pioneering experiments by Purcell andare Ramsey. [ Among the most important present bounds are of course similar definitions for otherreversal particles. even Since vector, the while electric field thedipole is spin a moment natural is interaction (polar), an time- is unnatural oddThus (axial), under non-zero time-reversal electric both dipole odd spatial moments vector, inversion reflect the and violation electric of time the reversal corresponding transformations. symmetries. and calculation [ ically for the electric dipole moment of the proton [ for atoms based on the indicated isotopes of tellurium and mercury, and neutrons. PoS(LHCP2016)047 ]. eV. 20 5 − Frank Wilczek ], centered at the Uni- 17 ], and several international gets larger both the mass and 15 , the scale of symmetry break- GeV. F F 10 ] proposes to develop magnet tech- 10 18 GeV, the axion mass is about 10 ≥ values, are at present in early stages of F 12 F 10 = ] have brought ideas from cavity QED into the F 19 9 ]. We realized that it implies the existence of a qualitatively 13 ][ . (I named the axion after a laundry detergent, noting that it cleaned 12 ]. This strategy exploits the basic interaction of axion electrodynamics, GeV, but within that range, given this ferment of activity and ideas, it axion 16 13 10 ≤ F ≤ ]. If one includes the axion field into the evolution of matter through the big bang, GeV, the axion fluid becomes an excellent candidate to supply a significant, and possibly 14 GeV 11 11 10 It has become a most important goal, both for fundamental physics and cosmology, either to The most mature approach to cosmic axion background detection relies on a strategy first pro- An enormous literature has grown up around axion physics [ Newer ideas, which may allow access to larger Steven Weinberg and I, independently, discovered a key consequence of PQ symmetry, which Due to their very specific connection with symmetry, one can calculate the expected properties John Preskill, Mark Wise and I discovered a most remarkable cosmological implication of ≥ In the presence ofnuclear perpendicular spins, magnetic which and in electric turn fields, induces this a will tiny but cause potentially precession detectable of oscillating the magnetic field. observe the cosmic axion fluid ora to recent rule it spike out. in activity This on is this a subject widely shared around perception, the as globe. evidencedposed by by Pierre Sikivie [ conferences have been either wholly orhave in evolved large and part matured, devoted to they the haveno subject. survived other While many comparably the years attractive central approach of ideas to intense the scrutiny. strong On P, T the problem other has hand, emerged. which allows an axion, in thesophisticated presence program, of named a ADMX magnetic field, (Axion to Dark convert Matter into eXperiment) a [ photon. A determined, discussion, which promises toto accelerate 10 the search process. The Sikivie strategy is best suited one finds that a veryEinstein substantial condensate, which density later of gets axionsF stirred survives, and initially mixed in by gravitational thethe self-attraction. form dominant, contribution of Indeed, to if a the cold mysteriousbe dark Bose- sufficient, matter and of its the other universe. properties Its are density consistent is estimated with to the observed properties of dark matter. versity of Washington, Seattle, is pioneering thisfor approach Axion experimentally. and The Precision new CAPP Physics) (Center nology initiative that in will South enable Korea a [ next-generationR. experiment. T. Brierley, Very recently S. Huaixiu M. Zheng, Girvin Matti and Silveri, K. W. Lehnert [ promises to reach the level of sensitivity required to detect the cosmic axion background. development. The CASPEr (Cosmic Axionof Spin a Precession cosmic Experiment) strategy axion relies background on to ability induce a small oscillating electric dipole moment in nuclei [ its authors had overlooked [ of axions in considerable detail, given the value of one parameter Theory Vision new kind of particle, the up a problem with axialThe currents.) axion The field axion helps screensconductor one the screen visualize electric potential how charge. PQ T-violating symmetry interaction, does analogously its to job: how electrons in a ing, which the theory does notwhose determine. interactions They are with predicted ordinary to matter bethe are extremely interactions extremely light spin-0 grow feeble. particles, smaller, As in proportion.There have For been many attemptsastronomical observations. to Taken discern together, they signals indicate of axions, including work at accelerators and axions [ PoS(LHCP2016)047 ] with the 22 Frank Wilczek singlet sectors generally do not interfere ) 1 ( U × 10 ) 2 ( SU × ) 3 ( SU ]. 21 As a mathematical discipline travels far fromsecond its and empirical third source, generation or only still indirectly more, inspired if bybeset it ideas with is coming very a from “reality” grave it dangers. is Itand becomes more more purely and l’art more purely pourseems aestheticizing, l’art. to more me ... to whenever beless this the directly stage rejuvenating empirical is return reached, ideas. to theconserve the I the only freshness source: am remedy and convinced the the that vitalitytrue re-injection this of in of the the was more future. subject a or and necessary that condition this will to remain equally In our quest to understand fundamental processes, we’ve built up a powerful world-describing 16. John von Neumann concluded his thoughtful address “The Mathematician” [ 14. When the talk was given, the fate of the 750 GeV gamma-gamma resonance was unde- Of course Nature gets the last word, but we get to set our15. priors, and On mine made the that other resonance hand new machinery. We’ve learned thatextremely symmetry powerful and conceptual forces, topology, shaping in theembodied the behavior in of quantum context field matter. of theory, We’ve is learned quantumthat a that physics, reliable “empty Nature, source are space” of interchangeable or parts.sive “vacuum” And (vacuum is we’ve polarization) learned best and substantial conceived (condensates). as These a lessons dynamical can be medium, applied both creatively, richly respon- following warning: His warning applies, I think, even more forcefully to theoretical physics. with unification or axion ideas,Higgs field, and by their providing existence low-dimension effective is interactions, not may open implausible. portals toOther Scalar those Worlds fields, sectors. such as the 4. Is That All There Is? Other Interactions cided. I said that it seemedin gratuitous, humility. and that The its preceding existence suggestions would for bedamental unification giving understanding among us of all an unwanted the T lesson forces, violation,true and seem for – to achieving and fun- me I’d hate compelling towithout – have new as to superstrong I’ve walk interactions, said, them or back. they evenquantitative more deserve The coupling radical to resonance departures unification. would be from have the been Itsuccess. ideas difficult is that to underlie explain hard to see how those departuresseem could improbable. fail to spoil that Theory Vision The ABRACADABRA (A Broadband/ResonantAmplifying Approach B-field Ring to Apparatus) strategy Cosmic is again Axionelectrodynamics, based Detection on but the uses with fundamental a interaction an of different axion presence geometry, better of adapted a to low magneticmagnetic frequencies, field field whereby [ the in the axion background induces a potentially observable oscillating PoS(LHCP2016)047 Frank Wilczek , 138 (1964). 13 . energy (4.1) ) + 1 − Z , Phys. Rev. Lett 1 − 652 (1973). A , 451 (1974). , 1681 (1981). ( 33 . 449 (2008), where it was adapted from S. Dürr et al. D24 , 438 (1974). 49 (2) . 11 . 32 . , 119 (2005). This is a comprehensive review of electric 456 Nucleus 318 → 20150257 (2016). Phys. Rev e Nature Phys. Rev. Lett ) + A374 Z , . Phys. Rev. Lett Prog. Theor. Phys A ( ]. Such reactions release far more energy than conventional nuclear 24 Annals of Physics ][ : FW’s work is supported by the U.S. Department of Energy under grant Nucleus 23 , 1224 (2008). Phil. Trans. R. Soc 322 Ah, Love! could thou and ITo with grasp Fate this conspire sorry Scheme ofWould Things not entire! we shatter it toRe-mould bits-and it then nearer to the Heart’s Desire! GeV range, that will not be easy. We will need major advances in accelerator technology, and dipole moments and issues around them, with extensive references. Science Acknowledgement We are left with the challenge of producing the monopoles. If their mass is in the expected 17. Stars are powered by nuclear energy, and in a few tens of billions of years they will run 18 [9] V. Anastassopoulos et al. arXiv:1502:04317 [8] M. Pospelov, A. Ritz [7] M. Kobayashi, T. Maskawa [3] F. Wilczek [5] S. Dimpoloulos, S. Raby, F. Wilczek [6] J. H. Christenson, J. W. Cronin, V. L. Fitch and R. Turlay [1] This figure is taken from F. Wilczek [2] H. Georgi and S. L. Glashow [4] H. Georgi, H. Quinn, S. Weinberg [10] S. Raby http://pdg.lbl.gov/2015/reviews/rpp2014-rev-guts.pdf. Contract Number DESC0012567. References a resolute building program. Givento the continue stakes, to it build is prototypes not with too ever-increasing soon energy reach. to start investing in the R+D, and 10 interactions. So one can imagine aan post-nuclear additional world, whose several hundred energy-based economy billions continues of for years. down. That will create a very constrainingthere environment may for be our a descendants’ activities. way out. Fortunately, catalyze Magnetic a monopoles are further a stage generic of feature burning, of by unified allowing theories, exothermic and reactions they such can as Theory Vision to craft materials which,accessed viewed from from the the outside, are inside, both are interesting and worlds useful. with Omar novel Khayyam’s properties aspiration which, when can be our inspiration. Thinking Way Ahead to proceed rapidly [ PoS(LHCP2016)047 Phys. Lett. B Frank Wilczek , 791 (1977). , 2058 (1982). D16 . D26 . , 137 (1983). , 127 (1983); L Abbott, P. Sikivie 120 Phys. Rev 120 Phys. Rev 12 , 25 (1977); Phys. Lett. B Vol. I no. 1 (University of Chicago Press, Chicago, 1947). It is 38 Phys. Lett. B . , 311 (1982). , 223 (1978). , 279 (1978). 40 , 1413 (1983). , 2141 (1982); 2141; . 40 B203 . 51 . . D25 . Phys. Rev. Lett Works of the Mind Nucl. Phys Phys. Rev. Lett Phys. Rev Phys. Rev. Lett Phys. Rev. Lett , 133 (1983); M. Dine, W. Fischler references, for the Particle Data Group: http://pdg.lbl.gov/2015/reviews/rpp2015-rev-axions.pdf. 120 also readily available online. Theory Vision [11] R. Peccei, H. Quinn [15] A. Ringwald, L. J. Rosenberg and G. Rybka edited a useful[16] review of axionP. Sikivie physics, with extensive [17] http://depts.washington.edu/admx/index.shtml [18] http://capp.ibs.re.kr/html/capp_en/ [19] H. Zheng, M. Silveri, R. T.[20] Brierley, S. M.D. Girvin Budker, and P. W. K. Graham, W. M. Lehnert Ledbetter,[21] S. arXiv:1607.02529 RajendranY. and Kahn, A. B. Sushkov Safdi and arXiv: J. 1306.6089 Thaler[22] arXiv:J. 1602.01086 von Neumann, in [12] S. Weinberg [13] F. Wilczek [24] C. G. Callan [23] V. A. Rubakov [14] J. Preskill, M. Wise and F. Wilczek