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    Kortewege de Vries equation

    In the Kortewege de Vries equation what is the physical origin of the linear and non-linear terms? I'm thinking of the explanation of a water wave here.What properties of the water molecules cause the profile and stability of the wave?
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    De broglie and electron transitions

    Is it possible that electron transitions from a high energy state to a low energy state are caused by the electrons interacting with some other partilces in the space around atoms.Let's look at the case of a hydrogen atom: According to Niels Bohr, for an electron, r = n^2 h^2 / (8 pi x epsilonx...
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    Mass caused by a field

    Is it the case that, for mass being caused by a particle being repelled by a field (the bigger the force of repulsion, the greater the mass), that the field has to give the relation, for one unit of mass: force is inversely proportional to [(distance between particle which has mass and...
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    Symmetry of electromagnetism

    Quarks can't exist in isolation and the electric charge on quarks can't exist in isolation from the electric charges of other quarks either.The electric charge of leptons like the electron can exist in isolation.Isn't electromagnetism showing a kind of asymmetry here: symmetry could be restored...
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    Harmonic oscillator

    If the universe oscillates between a Big Bang and a Big crunch, can two small volumes of dark energy, at opposite ends of it, be considered to be undergoing simple harmonic oscillation? The potential energy of an oscillator could be given by G m1 m2 /r where m1 is the mass of a volume of...
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    How big is an electron?

    Electrons are usually considered to be point-like particles but are there any theories that say they have a non-zero radius?
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    Uncertainty and energy

    An orbiting electron that is further from a proton has a higher energy . And is attracted to the proton by a weaker electric force. If space is filled with fast-moving particles they could push the electron closer to the proton and back to the groundstate so a photon would be emitted.For a...
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    Non-abelian gauge symmetry

    How does a non-abelian gauge symmetry lead to asymptotic freedom for quarks?
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    What is a time-like killing vector?

    What is a time-like killing vector?
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    Gluons and quarks and spin

    Under what circumstances could the colour force ( or the strong residual force) become repulsive between quarks? I've heard that changing the spin of a force carrier can in principle make a force repulsive when it was previously attractive.If gluons exchanged between quarks became fermions with...
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    Neutron stars and colour force

    If neutrons stay intact and get closer together than 10^-15 metres in a neutron star, would the exchange of mesons between neutrons stop and be replaced by the exchange of gluons, and would the gluons cause an attractive or repulsive force between neutrons? A repulsive force could stop the...
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    Can spin 2 yield rest masses?

    Would a massless spin 2 boson travelling at light speed collide with a fermion to yield particle-antiparticle pairs (if the spin 2 was a graviton the particles would have to have a very small mass so far undetected by science)? Could this spin 2 boson be electromagnetic in nature? Could a...
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    Neutron degeneracy pressure

    How can gravity overcome the degeneracy pressure of neutrons in a neutron star? Isn't such a thing the same as violating the uncertainty principle?
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    Pilot wave or standard QM

    The problem David Bohm's pilot wave theory has is that standard QM has been so successful and verified by experiment so many times that few physicists will not feel motivated to challenge it, and also Bohm's theory does not make predictions that are at odds with QM and therefore would allow a...
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    Frame dragging and rotation

    Is there a simple mathematical relation between the speed at which the Earth spins and the magnitude of the frame-dragging effect?
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    Entropy of a star

    How is the entropy of a star like the sun or a neutron star calculated?
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    Dark energy and pressure

    How does dark energy exert pressure - what does it push against.It must push against something solid if it has pressure units like Nm^-2?
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    Time taken to absorb neutrons,photons

    How long do particles take to change their mometum when they "bounce" off a surface and when they are absorbed by a surface? Do photons have a noticeably different "bounce" and absorption time to particles with rest mass? Can a neutron have a rest mass and be at rest in reality rather than...
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    Change in relativistic momentum

    Is it alright to say that force = rate of change of relativistic momentum F = [ m0 v2 / (1 - v2^2/c^2)^1/2 - m0 v1/(1 - v1^2/c^2)^1/2 )] / (t2 - t1) and can this relation be used to get sensible results for particles?
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    Decoherence for dummies and experts

    This is a link that shows a visual depiction of decoherence: and this is a link with the technical details of decoherence: [Broken] Is the second link saying that measuring...
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    QG plasma and gamma ray bursters

    Would a quark-gluon plasma reflect x rays and gamma rays and would such a plasma exist in gamma ray bursters and black holes?
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    Conservation of energy in GR and symmetry

    Experiment shows that many physical quantities are conserved and that the associated conservation laws can be linked to symmetries. However it seems strange that general relativity is a theory built from principles of symmetry and yet energy might not be conserved in general relativity.Surely...
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    Decoherence and carbon -60 [Broken] This weblink is about C60 buckyballs passing through a diffraction grating and showing wave-like behaviour.Since the buckyballs are moving quite slowly - about 210 m/s would it be possible to fire a neutron beam through the...
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    Higgs field

    If the Higgs theory is correct shouldn't it be able to predict the rest masses of all particles?
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    Singularity of a black hole

    When a star of a few solar masses collapses and starts to form a black hole, if the particles of which the star was made get closer and closer together as the density increases, will there come a point at which no force mediating particles have a short enough wavelength to get between the...
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    Thermohaline circulation

    When the flow of deep cold water in the atlantic speeds up what causes the amount of water vapour in the tropics to increase too.Could magma in the Earth be heating the sea water or hydrothermal vents - presumably sea currents would have to move to a hot spot or somehow encourage vents to...
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    Schwarzschild metric and BH mass

    What evidence is there that the schwarzschild metric is valid inside a black hole (as opposed to outside the Sun where evidence comes in the form of mercury's perihelion)? Also, if a black hole is made from photons, would it be massless and move at the speed of light?
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    Ocean currents and fluid pressure

    If we imagine a fluid travelling through a pipe as being a warm current of sea-water moving over a cold denser layer of sea-water, with the air immediately above the warm current forming one wall of the pipe, would the pressure of the warm current decrease as the current travels faster,and...
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    Free falling spinning rectangle

    A rectangular piece of paper spins rapidly about its longitudinal axis as it falls through the air.It takes longer to reach the ground than other shapes of paper.Why is this given that it spends a lot of time edge on to the flow of air and so encounters less resistance from the air than a...
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    Geostationary satellites

    How accurate does the orbiting velocity of a geostationary satellite have to be so that it keeps in synch with the same geographical part of the Earth over a period of ten years.