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The following is a list of unsolved problems grouped into broad area of physics.[1]

Cosmology and general relativityEdit
Cosmic inflationIs the theory of cosmic inflation correct, and, if so, what are the details of this epoch? What is the hypothetical inflaton field giving rise to inflation? If inflation happened at one point, is it self-sustaining through inflation of quantum-mechanical fluctuations, and thus ongoing in some extremely distant place?[2]Horizon problemWhy is the distant universe so homogeneous when the Big Bang theory seems to predict larger measurable anisotropies of the night sky than those observed? Cosmological inflation is generally accepted as the solution, but are other possible explanations such as a variable speed of light more appropriate?[3]Electroweak horizon problemWhy aren't there obvious large-scale discontinuities in the electroweak vacuum if distant parts of the observable universe were causally separate when the electroweak epoch ended? Standard cosmological inflation models have inflation cease well before electroweak symmetry breaking occurs, so it is not at all clear how inflation could prevent such discontinuities.[4]Future of the universeIs the universe heading towards a Big Freeze, a Big Rip, a Big Crunch, or a Big Bounce? Or is it part of an infinitely recurring cyclic model?Gravitational waveCan gravitational waves be directly detected?[5][6]Baryon asymmetryWhy is there far more matter than antimatter in the observable universe?Cosmological constant problemWhy does the zero-point energy of the vacuum not cause a large cosmological constant? What cancels it out?[7]

 


Estimated distribution of dark matter and dark energy in the universeDark matterWhat is the identity of dark matter?[3] Is it a particle? Is it the lightest superpartner (LSP)? Do the phenomena attributed to dark matter point not to some form of matter but actually to an extension of gravity?Dark energyWhat is the cause of the observed accelerated expansion (de Sitter phase) of the Universe? Why is the energy density of the dark energy component of the same magnitude as the density of matter at present when the two evolve quite differently over time; could it be simply that we are observing at exactly the right time? Is dark energy a pure cosmological constant or are models of quintessence such as phantom energy applicable?Dark flowIs a non-spherically symmetric gravitational pull from outside the observable Universe responsible for some of the observed motion of large objects such as galactic clusters in the universe?Ecliptic alignment of CMB anisotropySome large features of the microwave sky at distances of over 13 billion light years appear to be aligned with both the motion and orientation of the solar system. Is this due to systematic errors in processing, contamination of results by local effects, or an unexplained violation of the Copernican principle?Shape of the UniverseWhat is the 3-manifold of comoving space, i.e. of a comoving spatial section of the Universe, informally called the "shape" of the Universe? Neither the curvature nor the topology is presently known, though the curvature is known to be "close" to zero on observable scales. The cosmic inflation hypothesis suggests that the shape of the Universe may be unmeasurable, but, since 2003, Jean-Pierre Luminet, et al., and other groups have suggested that the shape of the Universe may be the Poincaré dodecahedral space. Is the shape unmeasurable; the Poincaré space; or another 3-manifold?
Quantum gravityEdit
Vacuum catastropheWhy does the predicted mass of the quantum vacuum have little effect on the expansion of the universe?Quantum gravityCan quantum mechanics and general relativity be realized as a fully consistent theory (perhaps as a quantum field theory)?[8] Is spacetime fundamentally continuous or discrete? Would a consistent theory involve a force mediated by a hypothetical graviton, or be a product of a discrete structure of spacetime itself (as in loop quantum gravity)? Are there deviations from the predictions of general relativity at very small or very large scales or in other extreme circumstances that flow from a quantum gravity theory?Black holes, black hole information paradox, and black hole radiationDo black holes produce thermal radiation, as expected on theoretical grounds? Does this radiation contain information about their inner structure, as suggested by Gauge-gravity duality, or not, as implied by Hawking's original calculation? If not, and black holes can evaporate away, what happens to the information stored in them (since quantum mechanics does not provide for the destruction of information)? Or does the radiation stop at some point leaving black hole remnants? Is there another way to probe their internal structure somehow, if such a structure even exists?Extra dimensionsDoes nature have more than four spacetime dimensions? If so, what is their size? Are dimensions a fundamental property of the universe or an emergent result of other physical laws? Can we experimentally observe evidence of higher spatial dimensions?The cosmic censorship hypothesis and the chronology protection conjectureCan singularities not hidden behind an event horizon, known as "naked singularities", arise from realistic initial conditions, or is it possible to prove some version of the "cosmic censorship hypothesis" of Roger Penrose which proposes that this is impossible?[9] Similarly, will the closed timelike curves which arise in some solutions to the equations of general relativity (and which imply the possibility of backwards time travel) be ruled out by a theory of quantum gravity which unites general relativity with quantum mechanics, as suggested by the "chronology protection conjecture" of Stephen Hawking?LocalityAre there non-local phenomena in quantum physics? If they exist, are non-local phenomena limited to the entanglement revealed in the violations of the Bell inequalities, or can information and conserved quantities also move in a non-local way? Under what circumstances are non-local phenomena observed? What does the existence or absence of non-local phenomena imply about the fundamental structure of spacetime? How does this relate to quantum entanglement? How does this elucidate the proper interpretation of the fundamental nature of quantum physics?
High-energy physics/particle physicsEdit

See also: Beyond the Standard Model


 


A simulation of how a detection of the Higgs particle would appear in the CMS detector at CERNHiggs mechanismAre the branching ratios of the Higgs boson consistent with the standard model? Is there only one type of Higgs boson?Hierarchy problemWhy is gravity such a weak force? It becomes strong for particles only at the Planck scale, around 1019 GeV, much above the electroweak scale (100 GeV, the energy scale dominating physics at low energies). Why are these scales so different from each other? What prevents quantities at the electroweak scale, such as the Higgs boson mass, from getting quantum corrections on the order of the Planck scale? Is the solution supersymmetry, extra dimensions, or just anthropic fine-tuning?Magnetic monopolesDid particles that carry "magnetic charge" exist in some past, higher-energy epoch? If so, do any remain today? (Paul Dirac showed the existence of some types of magnetic monopoles would explain charge quantization.)[10]Proton decay and spin crisisIs the proton fundamentally stable? Or does it decay with a finite lifetime as predicted by some extensions to the standard model?[11] How do the quarks and gluons carry the spin of protons?[12]SupersymmetryIs spacetime supersymmetry realized at TeV scale? If so, what is the mechanism of supersymmetry breaking? Does supersymmetry stabilize the electroweak scale, preventing high quantum corrections? Does the lightest supersymmetric particle (LSP or Lightest Supersymmetric Particle) comprise dark matter?Generations of matterWhy are there three generations of quarks and leptons? Is there a theory that can explain the masses of particular quarks and leptons in particular generations from first principles (a theory of Yukawa couplings)?Neutrino massWhat is the mass of neutrinos, whether they follow Dirac or Majorana statistics? Is mass hierarchy normal or inverted? Is the CP violating phase 0?[13][14][15]Color confinementWhy has there never been measured a free quark or gluon, but only objects that are built out of them, like mesons and baryons? How does this phenomenon emerge from QCD?Strong CP problem and axionsWhy is the strong nuclear interaction invariant to parity and charge conjugation? Is Peccei–Quinn theory the solution to this problem?Anomalous magnetic dipole momentWhy is the experimentally measured value of the muon's anomalous magnetic dipole moment ("muon g-2") significantly different from the theoretically predicted value of that physical constant?[16]Proton size puzzleWhat is the electric charge radius of the proton? How does it differ from gluonic charge?
Astronomy and astrophysicsEdit


 


Relativistic jet. The environment around the AGN where the relativistic plasma is collimated into jets which escape along the pole of the supermassive black holeAstrophysical jetWhy do the accretion discs surrounding certain astronomical objects, such as the nuclei of active galaxies, emit relativistic jets along their polar axes?[17] Why are there quasi-periodic oscillations in many accretion discs?[18] Why does the period of these oscillations scale as the inverse of the mass of the central object?[19] Why are there sometimes overtones, and why do these appear at different frequency ratios in different objects?[20]Coronal heating problemWhy is the Sun's corona (atmosphere layer) so much hotter than the Sun's surface? Why is the magnetic reconnection effect many orders of magnitude faster than predicted by standard models?Diffuse interstellar bandsWhat is responsible for the numerous interstellar absorption lines detected in astronomical spectra? Are they molecular in origin, and if so which molecules are responsible for them? How do they form?Gamma ray burstsHow do these short-duration high-intensity bursts originate?[21]Supermassive black holesWhat is the origin of the M-sigma relation between supermassive black hole mass and galaxy velocity dispersion?[22] How did the most distant quasars grow their supermassive black holes up to 109 solar masses so early in the history of the Universe?

 
Rotation curve of a typical spiral galaxy: predicted (A) and observed (B). Can the discrepancy between the curves be attributed to dark matter?
Kuiper cliffWhy does the number of objects in the Solar System's Kuiper belt fall off rapidly and unexpectedly beyond a radius of 50 astronomic units?Flyby anomalyWhy is the observed energy of satellites flying by Earth sometimes different by a minute amount from the value predicted by theory?Galaxy rotation problemIs dark matter responsible for differences in observed and theoretical speed of stars revolving around the center of galaxies, or is it something else?SupernovaeWhat is the exact mechanism by which an implosion of a dying star becomes an explosion?Three-body problemExact predictions for the positions of three (or more) bodies floating in space attracted by gravity.Ultra-high-energy cosmic ray[3] Why is it that some cosmic rays appear to possess energies that are impossibly high (the so-called OMG particle), given that there are no sufficiently energetic cosmic ray sources near the Earth? Why is it that (apparently) some cosmic rays emitted by distant sources have energies above the Greisen–Zatsepin–Kuzmin limit?[3][21]Rotation rate of SaturnWhy does the magnetosphere of Saturn exhibit a (slowly changing) periodicity close to that at which the planet's clouds rotate? What is the true rotation rate of Saturn's deep interior?[23]Origin of magnetar magnetic fieldWhat is the origin of magnetar magnetic field?Large Scale AnisotropyIs the Universe at very large scales anisotropic, making the Cosmological Principle an invalid assumption? The number count and intensity dipole anisotropy in radio, NRAO VLA Sky Survey (NVSS) catalogue[24] is inconsistent with the local motion as derived from CMBR[25][26] and indicate an intrinsic dipole anisotropy. The same NVSS radio data also shows an intrinsic dipole in polarization density and degree of polarization[27] in the same direction as in number count and intensity. There are other several observation revealing large scale anisotropy. The optical polarization from quasars shows polarization alignment over a very large scale of Gpc.[28][29][30] The Cosmic Microwave Background Radiation (CMBR) data shows several features of anisotropy[31][32][33][34] which are not consistent with the Big Bang model.Photon underproduction crisisWhy do galaxies and quasars produce about 5 times less ultraviolet light than expected in the low-redshift universe?Space roarWhy is space roar six times louder than expected? What is the source of space roar?Age-metallicity relation in the Galactic diskIs there a universal age-metallicity relation (AMR) in the Galactic disk (both "thin" and "thick" parts of the disk)? While in the local (primarily thin) disk of the Milky Way there is no evidence of a strong AMR,[35] a sample of 229 nearby "thick" disk stars has been used to investigate the existence of an age-metallicity relation in the Galactic thick disk, and indicate that there is an age-metallicity relation present in the thick disk.[36][37]The lithium problemWhy is there a discrepancy between the amount of lithium-7 predicted to be produced in Big Bang nucleosynthesis and the amount observed in very old stars?[38]Solar wind interaction with cometsIn 2007 the Ulysses spacecraft passed through the tail of comet C/2006 P1 (McNaught) and found surprising results concerning the interaction of the solar wind with the tail.Ultraluminous pulsarThe ultraluminous X-ray source M82 X-2 was thought to be a black hole, but in October 2014 data from NASA's space-based X-ray telescope NuStar indicated that M82 X-2 is a pulsar many times brighter than the Eddington limit.
Nuclear physicsEdit


 


The "island of stability" in the proton vs. neutron number plot for heavy nucleiQuantum chromodynamicsWhat are the phases of strongly interacting matter, and what roles do they play in the evolution of cosmos? What is the detailed partonic structure of the nucleons? What does QCD predict for the properties of strongly interacting matter? What determines the key features of QCD, and what is their relation to the nature of gravity and spacetime? Do glueballs exist? Do gluons acquire mass dynamically despite having a zero rest mass, within hadrons? Does QCD truly lack CP-violations? Do gluons saturate when their occupation number is large? Do gluons form a dense system called Color Glass Condensate? What are the signatures and evidences for the Balitsky-Fadin-Kuarev-Lipatov, Balitsky-Kovchegov, Catani-Ciafaloni-Fiorani-Marchesini evolution equations?Nuclei and nuclear astrophysicsWhat is the nature of the nuclear force that binds protons and neutrons into stable nuclei and rare isotopes? What is the origin of simple patterns[which?] in complex nuclei? What is the nature of exotic excitations in nuclei at the frontiers of stability and their role in stellar processes? What is the nature of neutron stars and dense nuclear matter? What is the origin of the elements in the cosmos? What are the nuclear reactions that drive stars and stellar explosions?Plasma physics and fusion powerFusion energy may potentially provide power from abundant resource (e.g. hydrogen) without the type of radioactive waste that fission energy currently produces. However, can ionized gases (plasma) be confined long enough and at a high enough temperature to create fusion power? What kinds of advances in material science must be made?
Atomic, molecular and optical physicsEdit
Hydrogen atomWhat is the solution to the Schrödinger equation for the hydrogen atom in arbitrary electric and magnetic fields?[39]Muonic hydrogenIs the radius of muonic hydrogen inconsistent with the radius of ordinary hydrogen?Abraham–Minkowski controversyWhat's the momentum of photons in optical media?
Condensed matter physicsEdit


 


A sample of a cuprate superconductor (specifically BSCCO). The mechanism for superconductivity of these materials is unknown.High-temperature superconductorsWhat is the mechanism that causes certain materials to exhibit superconductivity at temperatures much higher than around 25 kelvin? Is it possible to make a material that is a superconductor at room temperature?[21]Amorphous solidsWhat is the nature of the glass transition between a fluid or regular solid and a glassy phase? What are the physical processes giving rise to the general properties of glasses and the glass transition?[40][41]Cryogenic electron emissionWhy does the electron emission in the absence of light increase as the temperature of a photomultiplier is decreased?[42][43]SonoluminescenceWhat causes the emission of short bursts of light from imploding bubbles in a liquid when excited by sound?[44][45]TurbulenceIs it possible to make a theoretical model to describe the statistics of a turbulent flow (in particular, its internal structures)?[21] Also, under what conditions do smooth solutions to the Navier–Stokes equations exist? This problem is also listed as one of the Millennium Prize Problems in mathematics.Alfvénic turbulencein the solar wind and the turbulence in solar flares, coronal mass ejections, and magnetospheric substorms are major unsolved problems in space plasma physics.[46]Topological orderIs topological order stable at non-zero temperature? Equivalently, is it possible to have three-dimensional self-correcting quantum memory?[47]Fractional Hall effectWhat mechanism explains the existence of the \nu=5/2 state in the fractional quantum Hall effect? Does it describe quasiparticles with non-Abelian fractional statistics?[48]Bose–Einstein condensationHow do we rigorously prove the existence of Bose–Einstein condensates for general interacting systems?[49]

 


Magnetoresistance in a \nu=8/5 fractional quantum Hall state.Liquid crystalsCan the nematic to smectic (A) phase transition in liquid crystal states be characterized as a universal phase transition?[50][51]Semiconductor nanocrystalsWhat is the cause of the nonparabolicity of the energy-size dependence for the lowest optical absorption transition of quantum dots?[52]Electronic band structureWhy can band gaps not accurately be calculated?
BiophysicsEdit
Stochasticity and robustness to noise in gene expressionHow do genes govern our body, withstanding different external pressures and internal stochasticity? Certain models exist for genetic processes, but we are far from understanding the whole picture, in particular in development where gene expression must be tightly regulated.Quantitative study of the immune systemWhat are the quantitative properties of immune responses? What are the basic building blocks of immune system networks? What roles are played by stochasticity?HomochiralityWhat is the origin of the preponderance of specific enantiomers in biochemical systems?
Other problemsEdit
Entropy (arrow of time)Why did the universe have such low entropy in the past, resulting in the distinction between past and future and the second law of thermodynamics?[21] Why are CP violations observed in certain weak force decays, but not elsewhere? Are CP violations somehow a product of the Second Law of Thermodynamics, or are they a separate arrow of time? Are there exceptions to the principle of causality? Is there a single possible past? Is the present moment physically distinct from the past and future or is it merely an emergent property of consciousness? Why does time have a direction?Interpretation of quantum mechanicsHow does the quantum description of reality, which includes elements such as the superposition of states and wavefunction collapse or quantum decoherence, give rise to the reality we perceive? Another way of stating this is the Measurement problem – what constitutes a "measurement" which causes the wave function to collapse into a definite state? Unlike classical physical processes, some quantum mechanical processes (such as quantum teleportation arising from quantum entanglement) cannot be simultaneously "local", "causal" and "real", but it is not obvious which of these properties must be sacrificed or if an attempt to describe quantum mechanical processes in these senses is a category error that doesn't even make sense to talk about if one properly understands quantum mechanics.Theory of everything ("Grand Unification Theory")Is there a theory which explains the values of all fundamental physical constants?[21] Is the theory string theory? Is there a theory which explains why the gauge groups of the standard model are as they are, why observed space-time has 3 spatial dimensions and 1 dimension of time, and why all laws of physics are as they are? Do "fundamental physical constants" vary over time? Are any of the particles in the standard model of particle physics actually composite particles too tightly bound to observe as such at current experimental energies? Are there fundamental particles that have not yet been observed, and, if so, which ones are they and what are their properties? Are there unobserved fundamental forces implied by a theory that explains other unsolved problems in physics?Yang–Mills theoryGiven an arbitrary compact gauge group, does a non-trivial quantum Yang–Mills theory with a finite mass gap exist? This problem is also listed as one of the Millennium Prize Problems in mathematics.Physical informationAre there physical phenomena, such as wave function collapse or black holes, which irrevocably destroy information about their prior states? How is quantum information stored as a state of a quantum system?Quantum ComputationIs David Deutsch's notion of a universal quantum computer sufficient to efficiently simulate an arbitrary physical system?[53]Dimensionless physical constantAt the present time, the values of the dimensionless physical constants cannot be calculated; they are determined only by physical measurement.[54][55] What is the minimum number of dimensionless physical constants from which all other dimensionless physical constants can be derived? Are dimensionful physical constants necessary at all?

naruuuuuuu

Quote from: Totes not Naru or Gasai on July 06, 2015, 04:45:16 PM

Quote from: Elegiac on July 06, 2015, 04:41:04 PM

naruuuuuuu

I howl at the moon

nu uh

do you stare at neptuuuuuune?

Quote from: Vien on July 06, 2015, 05:18:02 PM

How do white holes exist if they break the second law of thermodynamics?

Because white holes don't exist.