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List of unsolved problems in physics - Quiz
Contributed by: Ball
  • 1. What is the hierarchy problem in high-energy physics?
A) It involves explaining why particles have mass through Higgs boson interactions.
B) The ratio between the strong force and gravity is on the order of 10−20, questioning why gravity is so much weaker.
C) It refers to the difficulty in unifying quantum mechanics with general relativity.
D) It concerns the discrepancy between observed and predicted values of dark matter density.
  • 2. What are magnetic monopoles, according to Paul Dirac?
A) Particles that carry 'magnetic charge' which could explain charge quantization if they existed in a past epoch.
B) They refer to the duality between electric and gravitational forces.
C) They are particles responsible for color confinement in quantum chromodynamics.
D) They are hypothetical particles with both electric and magnetic charges.
  • 3. What is the neutron lifetime puzzle?
A) It refers to the inconsistency in measuring the mass of neutrons.
B) It concerns the stability of neutrons within atomic nuclei.
C) A discrepancy exists between neutron lifetime measurements using 'bottle' versus 'beam' experimental methods.
D) It involves the unexpected decay of neutrons into protons and electrons.
  • 4. What is the proton decay problem?
A) It involves the interaction between protons and neutrons in nuclear reactions.
B) It concerns the role of protons in electromagnetic interactions.
C) It refers to the difficulty in measuring proton mass accurately.
D) The question of whether protons are fundamentally stable or decay with a finite lifetime as predicted by some extensions to the standard model.
  • 5. What is the goal of Grand Unification theories?
A) To explain the behavior of dark matter through unified force models.
B) To unify the electromagnetic and nuclear forces under a single symmetry governing their behaviors.
C) To describe the interactions between quarks and leptons in particle physics.
D) To provide a comprehensive theory for gravitational waves.
  • 6. What is supersymmetry's role at the TeV scale?
A) It aims to explain the hierarchy problem through additional dimensions.
B) It proposes a new form of symmetry between fermions and bosons at low energies.
C) It posits that spacetime supersymmetry might be realized, potentially stabilizing the electroweak scale and suggesting the lightest supersymmetric particle could comprise dark matter.
D) It suggests that all particles have superpartners with identical properties.
  • 7. What is color confinement in quantum chromodynamics?
A) The conjecture that color-charged particles cannot be separated from their parent hadron without producing new hadrons.
B) The phenomenon where quarks are permanently bound within protons and neutrons.
C) The process by which gluons mediate the strong force between quarks.
D) The theory explaining why particles have color charge.
  • 8. What is the QCD vacuum problem?
A) It refers to the difficulty in calculating the mass of gluons.
B) It involves understanding the behavior of quarks in high-energy collisions.
C) Non-perturbative QCD equations are unsolved, raising questions about how low-energy QCD leads to complex nuclei formation.
D) It concerns the interaction between dark matter and nuclear forces.
  • 9. Why are there three generations of quarks and leptons?
A) The reason for the existence of three generations and their specific masses remains unexplained by current theories.
B) They are necessary for the stability of atomic nuclei.
C) Each generation represents a higher energy state of matter.
D) They correspond to different types of fundamental interactions in nature.
  • 10. What is unknown about neutrino mass?
A) The absolute mass, whether they are Dirac or Majorana fermions, their mass hierarchy, and if the CP violating phase equals zero.
B) Neutrinos do not have mass according to the standard model of particle physics.
C) They are only massive in high-energy environments.
D) Their mass is known but varies depending on the type of neutrino.
  • 11. What is the reactor antineutrino anomaly?
A) It involves discrepancies in neutrino oscillation experiments.
B) Measured antineutrino flux from nuclear reactors is about 94% of expected values, with unknown causes such as sterile neutrinos or measurement errors.
C) It refers to the unexpected behavior of neutrinos in particle accelerators.
D) It concerns the detection of antineutrinos from cosmic sources.
  • 12. What is the strong CP problem?
A) It concerns the interaction between quarks and leptons.
B) The question of why the strong nuclear interaction is invariant to parity and charge conjugation, potentially solved by Peccei–Quinn theory with axions as dark matter.
C) It involves understanding the role of gluons in color confinement.
D) It refers to the discrepancy between predicted and observed neutron decay rates.
  • 13. What is the anomalous magnetic dipole moment issue?
A) The experimentally measured value of the muon's g − 2 differs significantly from theoretical predictions.
B) It involves discrepancies in electron spin measurements.
C) It refers to unexpected behavior in proton magnetic moments.
D) It concerns the alignment of atomic nuclei under magnetic fields.
  • 14. What are pentaquarks?
A) They are hypothetical particles with five identical quark types.
B) They are a type of exotic hadron formed only under extreme conditions.
C) They refer to the interaction between protons and neutrons in nuclei.
D) Possible combinations of quarks that may form tightly bound systems or weakly-bound pairings of a baryon and a meson.
  • 15. What is the mu problem?
A) It concerns the mass difference between muons and electrons.
B) It involves discrepancies in muon decay rates.
C) A concern in supersymmetric theories about understanding why certain parameter values exist.
D) It refers to the unexpected behavior of muons in magnetic fields.
  • 16. What is the Koide formula?
A) It is a formula predicting neutrino oscillation patterns.
B) It concerns the decay rates of heavy mesons.
C) A relation involving the masses of charged leptons, where their sum divided by the square of the sum of the roots equals approximately 2/3.
D) It describes the interaction between quarks and gluons in hadrons.
  • 17. What is strange matter?
A) It is a theoretical model for explaining neutron star composition.
B) A hypothetical form of quark matter that may be stable and could form strange stars, with unknown stability at zero pressure.
C) It involves the interaction between strange quarks in high-energy collisions.
D) It refers to a type of dark matter composed of strange particles.
  • 18. Do glueballs exist in nature?
A) They are known to form under specific conditions in particle accelerators.
B) They refer to the interaction between quarks and leptons.
C) The existence of glueballs, which are hypothetical particles composed solely of gluons, remains unconfirmed.
D) Glueballs are a type of exotic hadron confirmed by recent experiments.
  • 19. What is the solar cycle problem?
A) It refers to the discrepancy between observed and predicted solar luminosity.
B) It involves explaining the formation of sunspots on the solar surface.
C) It concerns the interaction between solar wind and Earth's magnetosphere.
D) Understanding how the Sun generates its periodically reversing magnetic field and similar processes in other stars.
  • 20. What is the flyby anomaly?
A) Unexpected changes in spacecraft velocity during Earth flybys, with unknown causes.
B) It refers to anomalies in satellite orbits around other planets.
C) It concerns unexpected behavior in interstellar space probes.
D) It involves discrepancies in measurements of gravitational waves.
  • 21. What is the origin of cosmic magnetic fields?
A) They are generated by interactions between dark matter and baryonic matter.
B) The mechanisms generating large-scale cosmic magnetic fields throughout the universe remain unclear.
C) They are remnants from the Big Bang, uniformly distributed across galaxies.
D) Cosmic magnetic fields originate solely from black hole activity.
  • 22. What causes fast radio bursts (FRBs)?
A) They are caused by interactions between cosmic rays and interstellar gas.
B) The cause of these transient radio pulses from distant galaxies is unknown, with several models proposed but none widely accepted.
C) They are generated by solar flares on distant stars.
D) FRBs result from the collision of neutron stars in binary systems.
  • 23. What is an example of holography in string theory?
A) General relativity
B) Quantum field theory
C) Loop quantum gravity
D) The AdS/CFT correspondence
  • 24. What is the nature of spacetime at the Planck scale according to loop quantum gravity?
A) Emergent
B) Discrete
C) Classical
D) Continuous
  • 25. Which correspondence in string theory is being generalized to gauge–gravity duality for arbitrary asymptotic spacetime backgrounds?
A) General relativity
B) Quantum field theory
C) AdS/CFT correspondence
D) Loop quantum gravity
  • 26. What does the AdS/CFT correspondence in string theory exemplify?
A) Holography
B) The cosmic censorship hypothesis
C) The black hole information paradox
D) The problem of time
  • 27. Which historical figure compiled a list of open problems in physics from 1971 to 2005?
A) Roger Penrose
B) Robert Bartnik
C) Vitaly Ginzburg.
D) Barry Simon
  • 28. What is the threshold problem in quantum computing?
A) How do qubits interact with classical bits?
B) Is it possible to use quantum computers for real-time weather prediction?
C) Can quantum computers solve NP-complete problems efficiently?
D) Can we go beyond the noisy intermediate-scale quantum era?
  • 29. What decay channel was used to identify pentaquarks?
A) Gravitational wave emission patterns
B) The Λ0b→J/ψK−p channel.
C) Quark-gluon plasma formation
D) Higgs boson decay channels
  • 30. Which event showed evidence against an associated supernova?
A) Collapsar event
B) GRB 170817A
C) Swift event GRB 060614
D) Supernova SN 1987A
  • 31. What discrepancy was resolved with updated solar metallicity measurements?
A) Solar abundance problem
B) Missing baryon problem
C) Pioneer anomaly
D) Faster-than-light neutrino anomaly
  • 32. Who first theorized the idea of a quantized time crystal?
A) Mikhail Lukin
B) Frank Wilczek
C) Norman Yao
D) Christopher Monroe
  • 33. In what year was evidence for time crystals shown in a laboratory setting?
A) 2016
B) 2012
C) 2014
D) 2015
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