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CERN Physicist Says Dark Matter May Be an Illusion 379

Posted by timothy
from the lunch-dark-matter-doubly-so dept.
anonymousNR writes "A CERN physicist has a new theory explaining the rotational curves of galaxies. 'The key message of my paper is that dark matter may not exist and that phenomena attributed to dark matter may be explained by the gravitational polarization of the quantum vacuum,' Hajdukovic told PhysOrg.com. 'The future experiments and observations will reveal if my results are only (surprising) numerical coincidences or an embryo of a new scientific revolution.' Given the many theories around explaining various observations in recent times, there seems to be a breakthrough on its way in our understanding of the cosmos."
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CERN Physicist Says Dark Matter May Be an Illusion

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  • TFA (Score:5, Informative)

    by mojo-raisin (223411) on Saturday August 13, 2011 @08:57PM (#37082112)

    Here's a link to the actual PDF (arxiv version) and not the pay version

    http://arxiv.org/ftp/arxiv/papers/1106/1106.0847.pdf [arxiv.org]

  • by Daniel_Staal (609844) <DStaal@usa.net> on Saturday August 13, 2011 @09:07PM (#37082144)

    Electromagnetism is stronger than gravity. Given that the particles in question also have the opposite charge, and are therefore attracted electromagnetically, it wouldn't make a major difference to them.

  • by Cyberax (705495) on Saturday August 13, 2011 @11:32PM (#37082736)

    "I'd like a bit of better evidence, please, before I swallow something like that."

    1) Rotational curves of galaxies.
    2) Gravitational lensing - it's too strong for the amount of baryonic matter present.
    3) Bullet cluster ( http://en.wikipedia.org/wiki/Bullet_cluster [wikipedia.org] ).
    4) Small galaxies - the smaller the galaxy the more dark-matter-dominated it is.

    The first one can be somewhat explained by MOND. But MOND can't really explain gravitational lensing (duh, it's Modified _Newtonian_ mechanics) and it is totally busted by 3) and 4). Vacuum polarization is MOND-like in this regard and probably can't explain them as well.

    Actually, the relationship between the amount of dark matter and normal matter in small galaxies is quite interesting. Unlike rotational curves and lensing it has an explanation that has nothing to do with gravitational properties of dark matter. Small galaxies have fairly shallow gravitational wells, so normal matter can be blown away by stellar winds and supernovae explosions. And since dark matter does not interact [much] with the normal matter, it tends to stay. Here's a nice overview: http://scienceblogs.com/startswithabang/2011/08/the_smallest_mini-galaxy_in_th.php [scienceblogs.com]

  • Re:no dark matter... (Score:4, Informative)

    by UnknowingFool (672806) on Sunday August 14, 2011 @01:06AM (#37083014)

    I have always had a hard time stomaching the theory that dark matter and dark energy exist.

    It was never a theory. Based on a number of different observations, physicists could not account for matter and energy that appear to be missing from our observable universe. It was only called dark matter and energy because there was no other way to describe. Based on other determinations, this energy and matter would have weird properties if it existed. Scientists have never actually said it existence but only it might exist. If they could account for this gap of observations due to empirical error, they would embrace it but different aspects of observations suggest that the gap is not easily explained. So right now the focus is on explaining the gap.

    Think of the difference between Newtonian and Relativistic models.

    I think you mean the difference between quantum theory and relativity. Relativity encompasses Newton's models for gravity.

  • by Roger W Moore (538166) on Sunday August 14, 2011 @01:49AM (#37083138) Journal

    And some types of dark matter are observed aka neutrinos.

    Neutrinos are too light to be Dark Matter. Their low mass means that they are produced moving at almost the speed of light so, if they were the Dark Matter, the "wrinkles" we see in the Cosmic Microwave Background would be far more blurred out than they are.

    If free neutrons didn't have such a short decay time, I'd consider that option as well.

    Sorry but neutrons interact via the strong nuclear force and so cannot be dark matter otherwise we would see it interacting with atomic nuclei.

    Without electrons the photon interaction with a neutron seems considerably hindered

    Electrons have nothing to do with photon interactions with neutrons. Neutrons are made of quarks so photons of sufficient energy can directly interact. Electrons can interact with neutrons either via EM (photon) or weak nuclear interactions.

  • Re:no dark matter... (Score:4, Informative)

    by Roger W Moore (538166) on Sunday August 14, 2011 @02:00AM (#37083168) Journal

    Dark matter is invisible, and if science has taught us anything repeatedly it is that nothing is invisible: End of story

    Electric fields, gravitational fields, magnetic fields, neutrinos, oxygen gas, nitrogen gas, carbon dioxide....don't mind me I'm just typing out loud.

  • by IICV (652597) on Sunday August 14, 2011 @02:35AM (#37083282)

    How can you possibly not know about the Bullet Cluster? [wikipedia.org] That is pretty much blatant evidence that there appears to be something there which is both dark and massive. Wouldn't a theory of dark matter be appropriate when presented with such evidence? (and, by the way, structures like the Bullet Cluster were predicted by the theory of dark matter - people said "well if it doesn't interact electromagnetically, we should be able to see places where normal matter got pushed but dark matter didn't, like when two clusters collide" - so they set out to look for something like that, and lo and behold they found it!)

    And that's not even going in to the other things that dark matter predicts and nothing else does, like the Cosmic Microwave Background.

    Or you could just read Starts with a Bang [scienceblogs.com], Ethan Siegel is a lot better at explaining this stuff than Slashdot is.

  • by maxwell demon (590494) on Sunday August 14, 2011 @03:02AM (#37083352) Journal

    But it doesn't fit the data -- the dark matter theory is constantly being revised. First it's "90%" of the mass of the universe, then it's "70%", then we're back to "98%", then there's dark energy, then the fractions change again, and again, and again.

    About the changing numbers, I'd like to see citations.

    Dark energy is a completely different concept than dark matter, completely independent of it, and used to explain completely different phenomena. The only thing dark matter and dark energy have in common is the adjective "dark".

    Note that we already know particles which have exactly the properties needed for dark matter: neutrinos. They are not massive enough to explain the observations, but they are a proof that particles of that kind can exist. It is of course not a proof that they do exist, but it shows that the idea is not as stupid as you want to make us believe.

    A classic example is the double-slit experiment [wikipedia.org]. Every textbook states a formula for the spacing of the interference fringes that disregards a bunch of things, handwaving them away as "unimportant".

    99% of all descriptions of the double slit experiment (and 100% of those in textbooks) are for explaining the properties of quantum mechanics, not for a quantitative description of an actual experiment. The unimportant parts are unimportant for understanding. It's like complaining that text books introducing free fall don't take into account air friction in their equations, despite the fact that air friction can even dominate a free fall.

  • Re:Bad science (Score:4, Informative)

    by haruchai (17472) on Sunday August 14, 2011 @03:06AM (#37083362)

    If you think that fundamentalists are a small, insignificant portion of US society, you must not be familiar with a small, insignificant portion of the government known as Congress.

  • by rknop (240417) on Sunday August 14, 2011 @03:41AM (#37083498) Homepage

    Dark Matter is not like the luminiferous aether.

    The luminiferous aether is a substance that was invented to explain something that seemed missing from our theories (specifically, what it is that the speed of electromagnetic waves given by Maxwell's Equations is relative to). It made predictions, those predictions were tested, and so the idea was tossed out.

    Dark Matter is a substance that was explained something that seemed missing from galaxies and clusters of galaxies (specifically, there wasn't enough mass there to explain why they held together given how fast things were moving). The idea of Dark Matter made predictions, those predictions were tested, and they *confirmed* Dark Matter.

    There's nothing magic about Dark Matter. And the lines of evidence are more than just some equations that don't balance out.

    More here: http://365daysofastronomy.org/2010/06/26/june-26th-dark-matter-not-like-the-luminiferous-ether/ [365daysofastronomy.org]

  • by Anonymous Coward on Sunday August 14, 2011 @03:42AM (#37083500)

    This is because it is the simplest theory which fits available data.

    But it doesn't fit the data

    Well, I am a physicist (doing my PHD, although not in astrophysics), and I can tell you that it certainly looks like the simplest theory that fits the data. I highly recommend Ethan's blog, who explains this very well, particularly http://scienceblogs.com/startswithabang/2011/03/good_ideas_bad_ideas_mond_and.php [scienceblogs.com] and
    http://scienceblogs.com/startswithabang/2009/09/dark_matter_part_i_how_much_ma.php [scienceblogs.com]. Notice, also, that theory predicts that the percentage of darks matter and energy changed during the history of our universe.

    Of course, the theory is not complete, and there should be further experimental confirmation, but it looks pretty good for now.

    This kind of thinking is all too common in Physics. A classic example is the double-slit experiment [wikipedia.org]. Every textbook states a formula for the spacing of the interference fringes that disregards a bunch of things, handwaving them away as "unimportant". A math-geek friend of mine in my physics class was upset by this lack of rigor, walked up to the whiteboard, and demonstrated that the simplifications can result in errors as large as ten percent or more in real-world scenarios!

    Imagine someone basing a new theory of light based on the difference between observed interference fringe spacing and the simplified theory. That would be stupid, wouldn't it? Why is it then acceptable for gravity?

    Well, I work in optics, and I have no clue what you are talking about here... Is it because the usual derivation uses tan(alpha) ~ sin(alpha) ~ alpha? Or because it disregards the polarization of light? I can assure you that both of those approximations are very good "in most cases". But that doesn't mean you can't use the correct formulas, if needed. More likely, your teacher was oversimplifying the problem to get accross the most important concepts without his students being drowned by little details.

    But much, much more importantly, physicists know that arriving to the simplest model that explains all your experimental data is very important, because it lets you understand what's going on, instead of just making blind calculations. I can assure you that this is not an easy skill to learn, specially for math-loving students who are irritated by approximations (I know this from first-hand experience!).

"Irrationality is the square root of all evil" -- Douglas Hofstadter

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