• Re: Iconic Black Hole Pioneer Disproves The Existence of Singularities

    From gharnagel@21:1/5 to Paul on Mon Jan 8 03:55:52 2024
    Paul wrote:

    Iconic black hole pioneer?

    "Anton Petrov is a math teacher.

    The paper Anton was referring to was by Roy Kerr:

    "Do Black Holes have Singularities?" https://arxiv.org/abs/2312.00841

    As Anton said, the spinning black hole metric is named after him.
    Frankly, the good news is that physicists are finally getting to the
    point where their beginning to reject infinities.

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  • From gharnagel@21:1/5 to Jan B. on Sat Mar 23 14:23:05 2024
    Jan B. wrote:

    Most (all?) physicist have thought for a long time that singularities in black holes
    result from the lack of a good quantum theory of gravity. GR is a classical theory and
    just like other classical theories (electrodynamics, Newtonian and Einsteinian mechanics)
    it leads to certain mathematical consequences which are non-physical. One well-known
    example of that in classical electrodynamics was the ultraviolet catastrophe which was only
    resolved by introducing quantum mechanics. Pretty much everyone in physics knows that
    something similar needs to happen with GR.
    It's all an old hat by now. Your barking at it as if you were holding the keys to some revelation is just silly.
    --
    Jan

    There is an infinity in SR when considering FTL phenomena, too. I'm sure you're familiar
    with the Bilaniuk, Deshpanda and Sudarshan paper with imaginary mass to cancel the gamma
    factor becoming imaginary for u > c. The relativistic velocity composition equation is

    u' = (u - v)/(1 - uv/c^2)

    where u' reverses sign at v = c^2/u. Bilaniuk et al took this as a real thing and proposed
    their "reinterpretation principle" to save causality. Many, many physicists preferred to
    view the RVCE as disproving the possibility of FTL, starting with Einstein and continuing
    to the present. A few hardy physicists have forged on anyway. Recami is still using the
    "reinterpretation principle" (which I think should be called RIP).

    It seems to me that the discontinuity (singularity?) at v = c^2/v represents the limit
    beyond which the RVCE is invalid. Using Tom Robert's language, it exceeds its domain of
    applicability. Thus, conclusions about FTL while using any equation that even implicitly
    involves the RVCE must be invalid. This includes four-momentum transformations and probably
    quantum field theory as well.

    What do you think?

    Gary

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  • From Tom Roberts@21:1/5 to gharnagel on Sun Mar 24 23:41:13 2024
    On 3/23/24 9:23 AM, gharnagel wrote:
    [...]

    I think that playing with the Lorentz transformation (LT) and the
    relativistic velocity composition equation (RVCE) are futile, because
    these are relationships among DIFFERENT COORDINATE SYSTEMS. But nature
    clearly uses no coordinates whatsoever, so coordinate relationships are irrelevant at the fundamental level [#]. That's why all modern physical theories are expressed in terms of tensors, which are naturally
    independent of coordinates [@]. For the LT and RVCE the relevant tensor
    is the 4-velocity of an object -- the LT and RVCE are formulated
    specifically so when an object's 4-velocity is projected onto the
    different inertial coordinate systems, the tensor itself remains
    unchanged (aka invariant).

    [#] Not to mention the artificial requirement of inertial
    coordinates.

    [@] There are other mathematical methods to ensure coordinate
    independence. Tensors are the simplest, due to their
    requirement of multi-linearity. Nonlinear approaches are MUCH
    more complicated, and to date no need for them has been
    demonstrated.

    Specifically, for a given inertial coordinate system (x^i) and an object
    with 4-velocity U, the components of U are:

    U^i = dx^i/dtau. {i=0,1,2,3}
    where tau is the proper time of the object, and d is
    partial derivative.
    We also have:
    U = U^i d/dx^i d is still partial derivative

    Note that dx^1, dx^2, and dx^3 need standard rulers for their
    definition, and dx^0 needs standard clocks, all of which must be at rest
    in the inertial frame. So it is impossible to define these relationships
    for coordinates moving faster than c relative to any inertial frame. IOW
    a tachyon cannot have a rest frame.

    Essential exercise for the reader:
    Given two inertial frames A and B, calculate the components
    of a given tachyon's 4-velocity relative to each; check
    whether the LT and RVCE hold for the tachyon. The essential
    question is: what does the norm of its 4-velocity mean?
    As A and B are inertial frames, the metric components for
    each are diag(-1,1,1,1).

    If you can't/won't do this exercise, you'll never really understand
    tachyons.

    Tom Roberts

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  • From Maciej Wozniak@21:1/5 to All on Mon Mar 25 07:55:44 2024
    W dniu 25.03.2024 o 05:41, Tom Roberts pisze:
    On 3/23/24 9:23 AM, gharnagel wrote:
    [...]

    I think that playing with the Lorentz transformation (LT) and the relativistic velocity composition equation (RVCE) are futile, because
    these are relationships among DIFFERENT COORDINATE SYSTEMS. But nature clearly uses no coordinates whatsoever, so coordinate relationships are irrelevant at the fundamental level [#].

    Sorry, poor halfbtrain. Nature doesn't, but we do,
    and your moronic physics does, so they ARE relevant
    at the fundamental level.



    That's why all modern physical
    theories are expressed in terms of tensors

    Does nature use tensors, poor halfbrain?
    Any example?

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  • From gharnagel@21:1/5 to Tom Roberts on Mon Mar 25 14:52:55 2024
    Tom Roberts wrote:

    I think that playing with the Lorentz transformation (LT) and the relativistic velocity composition equation (RVCE) are futile, because
    these are relationships among DIFFERENT COORDINATE SYSTEMS. But nature clearly uses no coordinates whatsoever, so coordinate relationships are irrelevant at the fundamental level [#]. That's why all modern physical theories are expressed in terms of tensors, which are naturally
    independent of coordinates [@]. For the LT and RVCE the relevant tensor
    is the 4-velocity of an object -- the LT and RVCE are formulated
    specifically so when an object's 4-velocity is projected onto the
    different inertial coordinate systems, the tensor itself remains
    unchanged (aka invariant).

    [#] Not to mention the artificial requirement of inertial
    coordinates.

    [@] There are other mathematical methods to ensure coordinate
    independence. Tensors are the simplest, due to their
    requirement of multi-linearity. Nonlinear approaches are MUCH
    more complicated, and to date no need for them has been
    demonstrated.


    Specifically, for a given inertial coordinate system (x^i) and an object
    with 4-velocity U, the components of U are:

    U^i = dx^i/dtau. {i=0,1,2,3}
    where tau is the proper time of the object, and d is
    partial derivative.
    We also have:
    U = U^i d/dx^i d is still partial derivative

    Note that dx^1, dx^2, and dx^3 need standard rulers for their
    definition, and dx^0 needs standard clocks, all of which must be at rest
    in the inertial frame. So it is impossible to define these relationships
    for coordinates moving faster than c relative to any inertial frame. IOW
    a tachyon cannot have a rest frame.

    Hi Tom,

    Thanks for reponding. Yes, tachyons always travel c < u < \infty

    Essential exercise for the reader:
    Given two inertial frames A and B, calculate the components
    of a given tachyon's 4-velocity relative to each; check
    whether the LT and RVCE hold for the tachyon. The essential
    question is: what does the norm of its 4-velocity mean?
    As A and B are inertial frames, the metric components for
    each are diag(-1,1,1,1).

    If you can't/won't do this exercise, you'll never really understand
    tachyons.

    Tom Roberts

    I have done the 4-momentum work and found that there is a problem for
    tachyons. Transformation yields P' = [γ(E/c - pv/c),γ(p - Ev/c^2)],
    yielding the belief that tachyon energy becomes negative for certain
    observers in other inertial frames. This occurs because |pc| > E for
    tachyons, contrary to the case for bradyons.

    The LT is the nuts and bolts of tensor transformations, so sometimes
    it's necessary to check that they still work in a new domain.

    A philosopher wrote:

    "Civilization advances by extending the number of important
    operations which we can perform without thinking of them."
    ― Alfred North Whitehead

    But that can cause problems when your only tool is a hammer and the
    new operation involves turning a screw. This is the situation with
    tachyons: The 4-vector approach is Whitehead, thinking like Bilaniuk
    et al. did in their Meta Relativity paper where they concluded that
    negative energy meant the tachyon would be observed to reverse direction
    and go back in time to boot (no one checked that the 3-momentum
    component didn't reverse direction).

    Tachyon energy is never observed to be negative, however, at the nuts
    and bolts level:

    For one thing, if E = mc^2/sqrt(u^2/c^2 - 1) can be considered as a law
    of physics, then E' = mc^2/sqrt(u'^2/c^2 - 1) must also be a law of
    physics by the Principle of Relativity. Looking at the transformation
    of E to E':

    E' = γmc^2 sqrt[(1 - uv/c^2)^2]/sqrt(u^2/c^2 - 1)

    E' = γE[(1 - uv/c^2)^2]^(1/2)

    we can see where the problem is: The 4-vector approach canceled the ^2
    exponent with the ^(1/2) exponent and left the (1 - uv/c^2) term in the transformation. This didn't cause problems for bradyons and luxons, but
    it does for tachyons when u > c^2/v. What is the square of a negative
    number? Positive, of course. What is the square root of a positive
    number? Well, it has two roots, one positive, one negative, but the
    positive root is the principle one. Furthermore, the fact that

    E' = mc^2/sqrt(u'^2/c^2 - 1)

    NEVER goes negative over the range c < u' < \infty signifies that we
    eschew the negative root.

    Sorry for the amount written here, but it seems to me that there is a
    lot of misinformation about tachyons that should be cleared up. All of
    this is in DOI: 10.13189/ujpa.2023.170101. Have you read it?

    Gary

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