Engineering and chemical thermodynamics. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. If you continue browsing the site, you agree to the use of cookies on this website. See our User Agreement and Privacy Policy. If you continue browsing the site, you agree to the use of cookies on this website. See our Privacy Policy and User Agreement for details. List of unsolved problems in physics. Some of the major unsolved problems in physics are theoretical, meaning that existing theories seem incapable of explaining a certain observed phenomenon or experimental result. The others are experimental, meaning that there is a difficulty in creating an experiment to test a proposed theory or investigate a phenomenon in greater detail. Unsolved problems by subfield? ABOUT THE AUTHOR Merle C. Potter, Ph.D., has engineering degrees from Michigan Technological University and the University of Michigan. He has coauthored Fluid Mechanics, Mechanics of Fluids, Thermodynamics for Engineers. Learn the concepts of Solved Problems Of Chemical Equilibrium with the help of study material for IIT JEE by askIITians. This book contains solutions to problems in the area of Heat Transfer, as per the syllabus of B.E. 1 Solutions to problems for Part 2 Sample Quiz Problems Quiz Problem 1. Write down the equation for the thermal de Broglie wavelength. Explain its importance in the study of classical and quantum gases. 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? What links the quantum arrow of time to the thermodynamic arrow? Interpretation of quantum mechanics. How 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 question regards the measurement problem: What constitutes a ? Unlike classical physical processes, some quantum mechanical processes (such as quantum teleportation arising from quantum entanglement) cannot be simultaneously ? Is there a theory which explains why the gauge groups of the standard model are as they are, why observed spacetime has 3 spatial dimensions and 1 temporal dimension, and why all laws of physics are as they are? Are any of the fundamental 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? Yang? This problem is also listed as one of the Millennium Prize Problems in mathematics. Physical information. Are 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? Dimensionless physical constant. At the present time, the values of the dimensionless physical constants cannot be calculated; they are determined only by physical measurement.? Are dimensionful physical constants necessary at all? Is Dirac large numbers hypothesis true? Fine- tuned Universe. What explains why the fundamental physical constants are set in the narrow range that is necessary to support carbon- based life? Cosmology and general relativity? 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?? Cosmological inflation is generally accepted as the solution, but are other possible explanations such as a variable speed of light more appropriate?? Or is it part of an infinitely recurring cyclic model? Size of universe. Diameter of the observable universe is about 9. Does a multiverse exist? Baryon asymmetry. Why is there far more matter than antimatter in the observable universe? Cosmological constant problem. Why does the zero- point energy of the vacuum not cause a large cosmological constant? 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 energy. What 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 flow. Is 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 anisotropy. Some large features of the microwave sky at distances of over 1. 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 Universe. What is the 3- manifold of comoving space, i. Neither the curvature nor the topology is presently known, though the curvature is known to be . The cosmic inflation hypothesis suggests that the shape of the Universe may be unmeasurable, but, since 2. Jean- Pierre Luminet, et al., and other groups have suggested that the shape of the Universe may be the Poincar. Is the shape unmeasurable; the Poincar? 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 radiation. Do black holes produce thermal radiation, as expected on theoretical grounds? Does this radiation contain information about their inner structure, as suggested by gauge? 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 dimensions. Does 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 conjecture. Can singularities not hidden behind an event horizon, known as ? 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 physics? Is there only one type of Higgs boson? Hierarchy problem. Why is gravity such a weak force? It becomes strong for particles only at the Planck scale, around 1. Ge. V, much above the electroweak scale (1. Ge. V, 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 anthropicfine- tuning? Planck particle. The Planck mass plays an important role in parts of mathematical physics. A series of researchers have suggested the existence of a fundamental particle with mass equal to or close to that of the Planck mass. The Planck mass is however enormous compared to any detected particle even compared to the Higgs particle. While working at the Rutherford Laboratory, Lloyd Motz suggested that such a particle with Planck mass likely had existed but that most of its mass had radiated away. Others have suggested particles with close to the Planck mass are micro black holes. It is still an unsolved problem if there exist or even have existed a particle with close to the Planck mass. This is indirectly related to the hierarchy problem. Magnetic monopoles. Did particles that carry ? If so, do any remain today? Or does it decay with a finite lifetime as predicted by some extensions to the standard model?? 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 matter. Why 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)?? Is mass hierarchy normal or inverted? Is the CP violating phase 0?? How does this phenomenon emerge from QCD? Strong CP problem and axions. Why is the strong nuclear interaction invariant to parity and charge conjugation? How does it differ from gluonic charge? Pentaquarks and other exotic hadrons. What combinations of quarks are possible? Why were pentaquarks so difficult to discover?? How do other solar- like stars generate their magnetic fields, and what are the similarities and differences between stellar activity cycles and that of the Sun?? Why is the magnetic reconnection effect many orders of magnitude faster than predicted by standard models? Diffuse interstellar bands. What 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? Supermassive black holes. What is the origin of the M- sigma relation between supermassive black hole mass and galaxy velocity dispersion? Can the discrepancy between the curves be attributed to dark matter? Kuiper cliff. Why does the number of objects in the Solar System's Kuiper belt fall off rapidly and unexpectedly beyond a radius of 5. Flyby anomaly. Why is the observed energy of satellites flying by Earth sometimes different by a minute amount from the value predicted by theory? Galaxy rotation problem.
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