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    Physics General Subjects Thread

    kvs
    kvs

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    Post  kvs on Fri Jun 07, 2019 9:57 pm

    Another article which properly solves for the point mass problem in GR:

    http://inspirehep.net/record/742738?ln=en

    Note the discussion at the end about the voodoo physics where by some magic a stress-energy tensor is
    not needed to solve systems which have mass and charge. That is just epic BS. The touted black
    hole solution does not have any point mass singularity. This homogeneous solution is being grossly
    misrepresented and in fact is just a repulsive space-time bubble which squeezes out a flat-space time
    into a semi-infinite shell. Actual singular (point mass) solutions do not have an event horizon.
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    Post  nomadski on Fri Nov 01, 2019 11:56 am

    Found this article about crack propagation. I have thought for some time that physical properties of the Earth can predict border formation in countries. By unknown variables of property. Such as altitude or area shared with sea coastline or temperature. Leading to fracture. Can this be simulated and predicted in computer? Like fracture in materials? If you look at small land mass connecting big land mass, then you get lots of small countries. Fractures. Or an island nation near big land mass, creates lots of small country or fractures. Area near sea contain fractures that run parallel to coast....

    https://www.google.co.uk/amp/s/phys.org/news/2010-03-physicists-mysteries-formation.amp
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    Post  kvs on Thu Feb 27, 2020 3:06 pm

    nomadski wrote:Found this article about crack propagation. I have thought for some time that physical properties of the Earth can predict border formation in countries. By unknown variables of property. Such as altitude or area shared with sea coastline or temperature. Leading to fracture. Can this be simulated and predicted in computer? Like fracture in materials? If you look at small land mass connecting big land mass, then you get lots of small countries. Fractures. Or an island nation near big land mass, creates lots of small country or fractures. Area near sea contain fractures that run parallel to coast....

    https://www.google.co.uk/amp/s/phys.org/news/2010-03-physicists-mysteries-formation.amp

    If they have an algorithm (e.g. set of governing equations) for this crack formation/propagation process then it can be implemented in
    computer code. But I think there are many empirical parameters in such cases and not some tightly closed set of equations that only need
    initial and boundary conditions.

    For example, there are no governing equations known for cells and organisms. We know about all sorts of processes but have no
    compact representation of them. And it is clear that cells and organisms are dynamical systems.
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    Post  kvs on Thu Feb 27, 2020 3:52 pm

    Einstein personality cult.

    Some facts to consider about the "all time genius":

    1) His 1905 paper on Special Relativity has zero references. That such a paper was published indicates corruption by the editors.
    Poincare published extensively on this very subject, including the Lorentz transform and E=mc2 before Einstein. But Einstein
    does not give any credit to Lorentz and to Poincare and others who were covering the same material in a non-trivial way. I am
    not talking about hints of similarity, I am talking about core features of the theory. Poincare even included relativity in
    the title of his theory and identified the growth of inertia as the speed of light is approached and that the speed of light
    was the limit in all inertial frames.

    The norm for scientific publications is to do a literature search and that has been true sine well before 1900. Einstein's SR
    paper was not publishable since he was ignoring previous research and taking credit for it. Some time later Einstein gave some
    credit to Lorentz but kept ignoring Poincare. Some will claim that SR is a deep insight by Einstein. That is BS since SR
    naturally pops out of the Maxwell Electro-Magnetic equations since they are invariant under Lorentz transforms. That is,
    inertial frames which are governed by Maxwell's equations (forget about gravity and general relativity for now) transform
    via the equations of Lorentz. These transforms are substantially different from the Gallilean transforms of Newtonian physics,
    and automatically include length contraction, time dilation and failure of simultaneity.

    For petty career and ego reasons scientists have been trying to pretend that they discovered SR when it has emerged from
    empirical observations. SR does not belong to Einstein.

    2) Eddington, staged what amounts to a hoax by claiming to have measured refraction of light around the Sun "proving"
    General Relativity during eclipse events in Africa in 1919. This data was totally cherry picked and he was claiming
    a measurement accuracy 200 times larger than was possible with his cameras. This farce was popularized in the press and
    turned Einstein into a celebrity overnight. The so-called three tests of GR do not prove its validity. There are an
    infinite number of theories including quantizable field theories that can reproduce all three tests but do not agree
    with GR.

    In the case of GR, Einstein can be given the credit. But he never put his foot down when his theory was abused. It
    is actually sad to see his 1939 paper totally ignored while the joke by Schneider and Oppenheimer from 1939 extolled
    as proof that GR allows black hole solutions. The latter paper used an unphysical stress-energy tensor which totally
    ignored radiation pressure to get their result. If they had accounted for any radiation pressure, they would never
    have obtained any solution forming a horizon. The proper stress-energy tensor for a perfect fluid is

    (rho + p) U^iU^j - p g^{ij}

    (beware a lot of references ignore the minus sign in the second term and are thus engaged in voodoo mathematics).
    This stress-energy tensor can be adapted to the "collapsing dust" case of Schneider and Oppenheimer (1939) since
    even a tiny radiation pressure from the dust (which is supposed to be like the galaxies in the universe) produces
    a strong negative feedback on the metric (g) curvature. As the mass gathers in progression to infinite density,
    it starts to form a horizon-like amplification of the radial prefactor, B(r):

    g = A(r)dt^2 - B(r)dr^2 - C(r)d(omega)^2

    For the black hole solution B(r) is infinity at the horizon radius (r_s). This infinity just does not pop out of
    nowhere. It must form. Here is where the radiation pressure comes in. The -p B(r) term in the stress-energy
    tensor will start to explode even if p is very small. Since this term acts to damp the formation of infinite density
    it is clearly acting to suppress the formation of any event horizon. As long as there is any radiation pressure,
    the horizon will fail to form for the dust system of Schneider and Oppenheimer. In the case of a collapsing
    star a similar resistance develops, but we are dealing with a compact object and not dispersed dust. For a star
    the pressure of the fluid (star material) acts as a positive term in terms of gravity. So it can theoretically
    overcome the radiation pressure. But there is a rub in this logic.

    In his 1939 paper Einstein identified an ultra-important physical aspect. Any BH collapse with the formation of
    a horizon requires matter to travel at the speed of light at the horizon. This means that mass turns into a photon
    gas at and inside the horizon. So we really need to know what happens to regular matter as the horizon starts to
    emerge. If the matter dissociates into photons before an actual singularity of B(r_s) forms, then we have a
    strong negative feedback that suppresses the formation of both infinite density and any event horizon. Although
    some state that is almost like a black hole can develop where we have a sphere of enormous density with an outer
    thick shell where B(r) is also very large. For all intents and purposes no real black hole forms but a black object
    does since any photons leaving this potential well will experience extreme red-shifting.




    kvs
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    Post  kvs on Thu Mar 05, 2020 5:21 am



    Modern astrophysics has gone off the rails.

    The key detail in this farce is that no amount of post-processing of observational data can create information that you have
    not obtained by measurement. In order to "interpolate" a 1250 fold increase in resolution and obtain structure below your
    pixel size, you need that much more information in some other form to do it.

    For example, suppose I have a 3x2 (or 3x6, whatever) pixel resolution camera and I need to image at 150x90 pixels. Then
    I need each pixel to be able to capture extremely small variations in intensity and also to be able to scan the region of interest.
    Over thousands of experiments and assuming the image does not change much during my measurement period, I can
    actually get enough pieces of information to assemble a 150x90 reconstruction. There is a process to "feel" over the true
    shape of the object by repeatedly touching it and recording variations.

    So in contrast to the claims of some of the idiot "scientist" posters in the comments below the video, no fancy algorithm
    can substitute for actual measurements. The video demonstrates that no such low-res scanning campaign was done to
    accumulate thousands of pieces of information to be able to reconstruct the true image. The data is limited to the 3x2 pixels
    shown and is thus forever trapped at this resolution.

    Also, in this case the argument that you do not need 150x90 pixels to resolve a 150x90 image cannot fly since the details
    are all well below the pixel size. If the image looked like the 3x2 pixels to start with, then trivially no higher res sampling is
    needed.

    Another cherry on top of this fraud turd cake, is that there is no physics model that would allow you to reconstruct sub-pixel
    structure based on some set of parameterizations (same thing as equations and algorithms). For earth system modeling we
    can have parameterizations of sub-grid scale processes such as convection based on the thermodynamics of water vapour and
    assumptions about convective structure based on observations (and these parameterizations do not actually capture convective
    plumes, but make statements of their stastical impact in the grid box). The BH image is not subject to some empirical equations
    that map the high res image to the low res blotch. Even imposing assumptions about sphericity and light bending bright
    halo, there is simply too much degeneracy in the blotch for any reconstruction. The coarse-res blotch image blends
    the high-res structure completely.

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