Chinese Scholar Yang Jian liang Putting Wrongs to Rights in Astrophysics

Discussion in 'Pseudoscience' started by heyuhua, Apr 22, 2018.

  1. NotEinstein Valued Senior Member

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    Nice find! I personally like this part most: "Notice that Newton’s theory is the approximation of low speed of general relativity, and general saying, celestial bodies’ speed are not very high, therefore the generalization of Newton’s theory is just the result of general relativity and the practical significance is apparent." We're talking about expanding spacetime, but let's ignore GR.

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  3. exchemist Valued Senior Member

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    Yes this taking on of the whole of geophysics - quite apart from astrophysics - is what I highlighted as so bonkers in post 2.
     
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  5. heyuhua Registered Senior Member

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    Last edited: Apr 24, 2018
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  7. heyuhua Registered Senior Member

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    you didn't, at all, read the presented articles :“Modification of Field Equation and Return of Continuous Creation - Galaxies Form from Gradual Growth Instead of Gather of Existent Matter”, "Correction of standard model in view of improved gravity equation”, “Modification of gravitational field equation and rational solution to cosmological puzzle” , if you really understand these articles you will have no doubt to the decelerated expansion and believe that universal expansion and contraction are cyclic, and matter is indeed creating continuously and the singularity both density and pressure were infinite didn't exist, and big bangs numerously happened in the past with density and pressure constant and still will go on in the future
     
    Last edited: Apr 24, 2018
  8. NotEinstein Valued Senior Member

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    None of those articles refer to the one I linked to, so they are most likely irrelevant to this part of the discussion. I'm not going to read three articles spanning about 50 pages when they aren't relevant.

    Then post or refer to the relevant sections here. Specifically, the parts that address and refute the paper I linked to.
     
  9. NotEinstein Valued Senior Member

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    But let's take a look at the first few pages of "Modification of Field Equation and Return of Continuous Creation" anyway. (I'm not going to comment on the sometimes broken English.)

    The introduction is mixing up cosmology and general relativity. For example, it says that inflation is a GR thing; it is not, it's a cosmology thing. Disproving inflation doesn't impact the validity of GR.
    The introduction calls the existence of dark matter a problem. That's plainly false: https://en.wikipedia.org/wiki/Dark_matter#Observational_evidence
    The introduction mentions the problem of the formation of stars and galaxies, without specifying what that problem is.
    "In fact, as verification or test to theory cosmological results should reflect the geological appearance on the earth and on the other hand the research to the earth can not disregard cosmological development, for natural world is unified in essence." This disregards the reasoning behind the separating of these fields in science. According to existing scientific models, the two don't influence each other, so the separation is warranted. Of course, if evidence to the contrary is produced, science will have to treat them as one, but until this evidence is found, there is no reason to demand these to be treated as one. Although, admittedly, the very next sentence states: "A sharp instance is that observations show indisputably the earth is expanding but so important phenomenon can not yet obtain due explanation from cosmology or astrophysics until today ...", so I guess we'll get to the evidence for this in this paper. Seems weird to chastise science for doing the right thing (not complicating things without reason), though.
    "Besides, there are also some logical confusions, for example on one hand say universal temperature descends all the time after big bang and on another hand say the sun is burning more and more brightly, its temperature is becoming higher and higher." This is of course a laughable logical mistake made by the author: a global temperature drop doesn't mean locally the temperature can't increase. I point to global warming and entropy as two other examples of this.

    Section 1.1
    "where γ is the coupling coefficient" Note that this gamma isn't the Lorentz factor. The version of the EFE used here is also mentioned here: https://en.wikipedia.org/wiki/Einstein_field_equations#Equivalent_formulations Under: "For example, in D = 4 dimensions this reduces to"
    The expression given for the stress-energy tensor is for a perfect fluid in thermodynamic equilibrium. In other words, this isn't its general form; we are deriving things for a special case.
    In the following bog-standard derivation, the metric is taken to be Minkowski with only small perturbations. Higher order terms are ignored.
    Equation 1.2 assumes a harmonic condition for the perturbations.
    Then, a static case is assumed, followed by the enforcing of particular behavior of the metric at long range (= far away from any source). This thus means we're in a situation where there's a (cluster of?) bubble(s) of perfect fluid, statically, in thermodynamic equilibrium, surrounded by a vacuum. I'm not sure that's even possible? How would the outer layers of this fluid stay in place? But if everything is static, then what use is this universe anyway? The kinetic mass of a moving particle is given. But we have no particles; we have a perfect fluid. ... Are those alarmbells I'm hearing? ... At this point, gamma needs to be defined differently from the standard. ... Yep, definitely alarmbells.

    heyuhua: Please explain how you can meaningfully talk about a particle when all you've got is a perfect fluid. Please explain how a particle can be in motion, if the universe is static.
     
  10. NotEinstein Valued Senior Member

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    Oh, and by the way, for any readers vaguely interested: that change in gamma is indeed the modification. In other words, Jian Liang Yang proposes to change the EFE from:
    \(R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}=-8\pi GT_{\mu\nu}\)
    to:
    \(R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}=4\pi GT_{\mu\nu}\)

    Yes, the sign is now flipped. I think that can safely be summarized as: gravity is now repulsive. It's the invention of anti-gravity!
     
  11. Q-reeus Valued Senior Member

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    I have no interest in reading through the OP's 'theory', but noticed your signs for standard vs 'modified' RHS of EFE's. Surely it's the reverse, with standard form positive as given here:
    https://en.wikipedia.org/wiki/Einstein_field_equations#Mathematical_form

    PS: Just noticed there is a sign convention ambiguity which I was not previously aware of:
    https://en.wikipedia.org/wiki/Einstein_field_equations#Sign_convention
    Evidently a carry over from the +--- vs -+++ sign convention in Minkowski metric.
     
    Last edited: Apr 24, 2018
  12. heyuhua Registered Senior Member

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    Now I doubt that you do not know where the conclusion of accelerated expansion come, if you know this your problems will not exist
     
  13. exchemist Valued Senior Member

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    post deleted
     
  14. heyuhua Registered Senior Member

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    you are taking a error, in fact it doesn't represent the gravity becomes repulsive that the sign is positive or negative, the important thing is the behavior of geodesic equation, which is decided by metric, the new metric derived out of the modified field equation still makes sure gravity, and about the details you may see Yang's articles
     
    Last edited: Apr 24, 2018
  15. NotEinstein Valued Senior Member

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    Yang uses the -+++ convention in the paper. This is mentioned explicitly (page 6), and the given expression of the EFE in the paper confirms this (eq 1.1). The flipping of the sign is explicitly mentioned as well (near the bottom of page 7). In other words, there’s no sleight of hand being done here with sign conventions: the sign truly flips with respect to the standard EFE in Yang's paper.

    So you cannot point to something addressing the paper I posted, and thus cannot refute it, which means the paper you posted is countered.

    This is a literal copy-paste from your own paper; any mistake made is yours.

    Well, it effectively inverts the contribution of the stress-energy tensor on the curvature of spacetime. How else am I supposed to interpret that?

    No, the most important thing is that it needs to match reality. A flipped sign (and a factor 2) surely would have been noticed by now!

    You can't modify the EFE and modify the metric to counteract the change (if that even works), and then call your equation different. If it's just convention/notational changes, you haven't done anything new. No, Yang's claim that the sign flips is exactly that: a claim that the standard EFE is off by a minus-sign and a factor 2. It inverts the contribution of the stress-energy tensor to the curvature, no matter what tricks you apply to the metric.

    Obviously Yang's claims have been experimentally falsified. While the EFE as it stands today might not be the end-all solution, clearly dropping in a minus-sign and a factor of 2 is not a viable modification.
     
  16. heyuhua Registered Senior Member

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    you will not understand some of the subtleties of the original Yang's articles if you don't have an open mind to learn, your comments are childishly simplistic.
     
  17. heyuhua Registered Senior Member

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    I am sure that you aren't familiar with the calculating details of general relativity, in fact, it doesn't decide force's behavior directly whether the sign is positive or negative, because only the metric get into the geodesic equations which decide the behavior of force. It is worthwhile to note that now pressur takes negative but not previous zero or positive, the negative pressure changes the space-space components of metric and doesn't change time-time component.
    you will not understand some of the subtleties of the original Yang's articles if you don't have an open mind to learn, your comments are childishly simplistic. In a word, to understand Yang's opinion you must be familiar with the calculating details of general relativity,
     
  18. Michael 345 Bali tonight Valued Senior Member

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    Do any of the previous post indicate gravity is no longer a attraction force but a repulsion force?

    Is it safe to go outside while you lot are debating this?

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  19. Xelasnave.1947 Valued Senior Member

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    General Relativity does not treat gravity as a force but as an alteration in space time.

    General Relativity is a model and of course another model can treat it differently ... its just that there are no models that come close to replacing General Relativity.
    Alex
     
  20. Michael 345 Bali tonight Valued Senior Member

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    I don't care how it's treated - CAN I GO OUTSIDE?

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  21. NotEinstein Valued Senior Member

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    I'm childishly simplistic (by the way, please don't insult people), but you can't even explain the kind of universe this EFE is supposed to be valid for? I'm childishly simplistic, but you can't even explain what the flipping of the sign means. I'm childishly simplistic, but you apparently don't consider it important to check whether a hypothesis matches reality.

    Well, one of us two indeed is.

    Yes, it's safe (well, safe gravity-wise...). Reality doesn't conform to some arbitrary hypothesis; it's the goal of science to conform to reality. So somebody inverting gravity on paper is perfectly harmless.

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  22. Michael 345 Bali tonight Valued Senior Member

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    Phew

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  23. heyuhua Registered Senior Member

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    It is obviously wrong to think the sign to decide attraction or repulsive , your perspective indicates you didn't go deep into calculating details, you should know field equation is the equation that decides metric components and doesn't represent attraction or repulsive, it is the geodesic equation that give expression to attraction or repulsive. I sharply tell you that Yang's new theory matches well reality, hope you be humble enough to learn from Yang's theory
     
    Last edited: Apr 26, 2018

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