Cosmology Fine tuning News

Aeon writer asks: Has dogma derailed the search for dark matter?

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3-D impression of dark matter via Hubble

Probably, but let’s let him tell it: From Pavel Kroupa at Aeon:

The issues at stake are huge. Acceptance of dark matter has influenced scientific thinking about the birth of the Universe, the evolution of galaxies and black holes, and the fundamental laws of physics. Yet even within academic circles, there is a lot of confusion about dark matter, with evidence and interpretation often conflated in misleading and unproductive ways.

The first step is that we need to revisit the validity of Newton’s universal law of gravitation. Starting in the 1980s, Mordehai Milgrom at the Weizmann Institute in Israel showed that a small generalisation of Newton’s laws can yield the observed dynamics of matter in galaxies and in galaxy clusters without dark matter. This approach is broadly known as MOND (MOdified Newtonian Dynamics). Milgrom’s correction allows gravitational attraction to fall off with distance more slowly than expected (rather than falling off with the square of distance as per Newton) when the local gravitational acceleration falls below an extremely low threshold. This threshold could be linked to other cosmological properties such as the ‘dark energy’ that accounts for the accelerating expansion of the Universe.

These links suggest a deeper fundamental theory of space, time and matter, which has not yet been formulated. Few researchers have pursued such an alternative hypothesis, partly because it seems to question the validity of general relativity. However, this need not be the case; additional physical effects related to the quantum physics of empty space and to the nature of mass might be playing a role. MOND also faces its own challenges, both observational and theoretical. Its biggest drawback is that MOND is not yet well-anchored to general relativity. Because of the prevailing dark-matter dogma, few scientists dare to build on Milgrom’s ideas. Young researchers risk not getting a job; senior researchers face losing out on grants.More.

<em>Coffee</em> TinsRisk not getting a job? Hey, we should introduce this guy to some non-Darwinian biologists.MUFFINS

Seriously, a thought experiment: What if it became clear that no correct description of the nature and role of dark matter provided any support for a multiverse? Would the same people still be interested?

One hesitates to suggest that a correct description would make the multiverse less likely because there is simply no evidence for it now—and logically something can’t be less than nothing. (?)

But the desire to avoid the implications of the fine-tuning of the universe for life keeps the spectre floating over the witch’s vat.

See also: A proposed dark matter solution means gravity is an illusion

and

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6 Replies to “Aeon writer asks: Has dogma derailed the search for dark matter?

  1. 1
    PaV says:

    Because of the prevailing dark-matter dogma, few scientists dare to build on Milgrom’s ideas. Young researchers risk not getting a job; senior researchers face losing out on grants.

    Dogma in science?!? Say it isn’t so!!

  2. 2
    PaV says:

    For what it’s worth, my own musings on unification of GR (general relativity) and QM (QED and QCD) give an explanation for both dark energy and dark matter. In a sense, they’re the same thing, but at different dimensions. And it’s consistent with all observations so far. In fact, any ‘particle’ observation would disprove my ideas.

    All of this is possible with just a simple addition to our understanding of ‘space.’ This ‘addition’ is right before the eyes of all scientists involved in such matters. I see them dancing around the solution, but never embracing it. And why? Because it would make the problem that the Big Bang represents to atheists seem like 2+2=4. It is not a mathematical problem; it is a philosophical/religious problem.

  3. 3
    daveS says:

    PaV,

    For what it’s worth, my own musings on unification of GR (general relativity) and QM (QED and QCD) give an explanation for both dark energy and dark matter. In a sense, they’re the same thing, but at different dimensions. And it’s consistent with all observations so far. In fact, any ‘particle’ observation would disprove my ideas.

    Have you considered publishing your theory?

  4. 4

    The author, Pavel Kroupa, is promoting his Modified Newtonian Dynamics (MOND) as the non-dogmatic solution to dark matter. Strangely, he’s competing with all sorts of other non-Newtonian, non-Standard Model hypotheses–SUSY, axions, dark sector, etc. Yet he thinks that his is being excluded because of dogma! It might just be better to call this thing “group think” or what Roger Penrose refers to in his new book “fashion, faith and fantasy”. MOND hasn’t made it to the “fashion” category, though judging by its advocates, it is certainly faith and a little bit fantasy.

    Why? Because it invokes the same sort of “dark sector” special pleading, that Newton’s laws of gravity fail for just a certain combination of distances and speeds. Now if we have learned anything from particle physics, it is that the distances over which forces operate is correlated to their masses of their mediating particles, so MOND is also a theory about gravitons–which is rapidly moving into the fantasy world.

    I have just submitted a paper saying that dark matter can meet all the observational criteria by being composed of black, crusty, comets. No special forces, no special particles, no dark sector, no fantasy involved. So why isn’t such a simple model being discussed? Penrose nails it–fashion, faith and fantasy sell better.

  5. 5
    PaV says:

    daveS:

    To publish a paper you need to have a well-defined mathematical structure. My theory is a concept—that has held up for six years against all new and old observations—searching for such a structure.

    I have an intuitive notion of just how to attack the problem of unification, but physics is so mathematically sophisticated these days that it requires a huge amount of classwork; and one doesn’t do this in their spare time.

    These days, if you can’t couch it in this kind of sophistication, physicists won’t pay any attention.

    I see them inching closer, and hope they’ll get there, so that I can see what the final form looks like. But, as I think I said above, I don’t think I’ll live to see it. Maybe.

    The one thing that makes me think I’m really onto something is that it is said that some new understanding is needed, and that when it is found, everyone will respond: “Why didn’t I think of that.” And that, pretty much, is what the idea is. It’s very radical, very fundamental, and yet, very simple.

    I’m keeping my fingers crossed that someone will see what I think is right there in front of our noses.

    The notion I have has to do with our understanding of the “vacuum.” Everyone nowadays says that the “ether” doesn’t exist; but, the reality is that Einstein, after postulating his General Theory came very quickly to the notion that an “ether”—but not the one that was supposed in the electrodynamics of Maxwell and so on—had to exist. Eventually, Einstein would equate his early notion of the “ether” with “space-time,” and the modern notion of the “vacuum” is basically what Einstein had in mind, and you’ll see these terms used almost interchangeably. The modern notion of the “vacuum” has to do with QM, and specifically QED, which involves what is called a “second quantization” and specifies “creation” and “annihilation” operators. It’s these “operators” (i.e., mathematical structures involving matrices) that account, ultimately for “electron-positron” pairs “popping in and out of existence.” But behind all of this, the “gauge” transformations that are needed still involve the scalar and vector potentials used as a “mathematical device” in EM. So these potentials never really go away; and I think that deserves some attention.

    I think they’re taking something for granted, and not questioning what they’re dealing with. IOW, the scalar potential, phi, and the vector potential, A, are simply assumed to stand for something ( but a ‘something’ that you ‘add,’ and then ‘remove’, which is what happens in getting to the wave equations of EM), and they prove useful; yet, no one questions what this might be. There’s something called the Abrahmov-Bohm effect that says there may be actually some physical reality to these potentials. That’s kind of where I’m searching around for answers.

    I see that Robert Sheldon has something on this topic, and he mentions “axions.” A lot of my thinking is really summed up quite well in this notion of an “axion” particle. But, it’s not exactly that; but close.

    The notion of the “axion” itself comes from the CP (charge-parity) violation (a symmetry is lost in the equations) of the strong force in QCD–quantum chromodynamics. [The “charge” in QCD is treated much like the “charge” in EM; but instead of one single charge, you have three charges, and these charges are red, green and blue (if you add all three charges, you get ‘white’: that is, they cancel one another out.) So, don’t get too thrown off by the “chromo” part of QCD]

    One way of putting my thoughts on paper would be this (again, quite simple): the “strong force” curves space locally (and to a great degree) through it’s direct effects, and it curves space globally (and to a lesser degree; i.e. GR=gravity) through its long-range effects; i.e., the presence of ‘matter’.

  6. 6
    daveS says:

    PaV,

    Ok, thanks for elaborating.

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