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Thread: Negative mass? say what?

  1. #1
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    Question Negative mass? say what?

    Having difficulty getting my head around this one. [BTW sorry for being slow in posting recently, life got in the way-REM]


    https://phys.org/news/2018-12-univer...cosmos.html#ms

    Bringing balance to the universe: New theory could explain missing 95 percent of the cosmos

    December 5, 2018, University of Oxford

    Scientists at the University of Oxford may have solved one of the biggest questions in modern physics, with a new paper unifying dark matter and dark energy into a single phenomenon: a fluid which possesses 'negative mass." If you were to push a negative mass, it would accelerate towards you. This astonishing new theory may also prove right a prediction that Einstein made 100 years ago.

    Our current, widely recognised model of the Universe, called LambdaCDM, tells us nothing about what dark matter and dark energy are like physically. We only know about them because of the gravitational effects they have on other, observable matter.

    This new model, published today in Astronomy and Astrophysics, by Dr. Jamie Farnes from the Oxford e-Research Centre, Department of Engineering Science, offers a new explanation. Dr. Farnes says: "We now think that both dark matter and dark energy can be unified into a fluid which possesses a type of 'negative gravity," repelling all other material around them. Although this matter is peculiar to us, it suggests that our cosmos is symmetrical in both positive and negative qualities."
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    Mark Twain, Life on the Mississippi (1883)

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    The article makes a big leap from a "proposed new theory" to "may have solved" just to get readers.
    Depending on whom you ask, everything is relative.

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    Quote Originally Posted by Roger E. Moore View Post
    ..."We now think that both dark matter and dark energy can be unified into a fluid which possesses a type of 'negative gravity"....
    Regardless of the negative gravity bit, dark matter and dark energy have entirely different effects, and "operate" in different-sized arenas. Dr. Farnes has apparently made an interesting model. Sounds a little hand-wavy. "Dr. Farnes' research applies a 'creation tensor"...." Yes, he keeps pumping this negative mass into the universe... This seems consistent with dark energy, but not dark matter. I don't see the unification.
    Everyone is entitled to his own opinion, but not his own facts.

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    Voids do seem to expand faster than regions with galaxies

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    You might enjoy reading this blog's discussion of the topic, and the many comments which follow.

    http://backreaction.blogspot.com/201...-have-not.html

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    Quote Originally Posted by StupendousMan View Post
    You might enjoy reading this blog's discussion of the topic, and the many comments which follow.

    http://backreaction.blogspot.com/201...-have-not.html
    Enjoyed - yes. Thanks!

    A particularly good comment from Sabine:

    You need to introduce some weird stuff new stuff, then you need to introduce the creation tensor, then you need to assume you have no problem with vacuum stability, then you need to somehow assume that you get around the issue with the spin-2 field while still using GR, then you need to explain how come that a negative cosmological constant is actually in agreement with all the data, and even if you have done that you'd still have to bend over backward to demonstrate that the solution actually does fit the rotation curves which, frankly, I am rather skeptic about because I cannot see how you get the right scaling behavior (Tully-Fisher and all).
    Everyone is entitled to his own opinion, but not his own facts.

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    Whoops, forgot to mention that JoeBakhos ATM idea was moved from this thread to here.
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    I just hope there is a STAR DRIVE somewhere in the new theory

    ie some way to use the new facts in a useful way to get to other systems that we do not yet understand

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    Quote Originally Posted by mkline55 View Post
    The article makes a big leap from a "proposed new theory" to "may have solved" just to get readers.
    Yes, I see a lot of this lately. Annoying, it is.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    Mark Twain, Life on the Mississippi (1883)

  10. #10
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    Quote Originally Posted by Roger E. Moore View Post
    Yes, I see a lot of this lately. Annoying, it is.
    I will second that. In my experience many of these Universe Today articles have faults that are commonplace in popular media writing on these topics.

  11. #11
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    Quote Originally Posted by Roger E. Moore View Post
    If you were to push a negative mass, it would accelerate towards you.
    So what would happen if you where suspended in a fluid of "negative mass"? If it's on all sides of you and you moved even just slightly to one side that side would accelerate towards you, pushing you in the opposite direction. But then the fluid on the other side of you would start pushing towards you as well, pushing you back to the other side which would cause that side to push even harder in the other direction, and it sounds like very quickly you would get into a runaway situation where the pressure on all sides of you constantly increases since the negative mass is always accelerating towards the force rather then away from it.

    Or am I thinking of this all wrong? It sounds like really weird stuff.

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