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CERN Physicist Says Dark Matter May Be an Illusion
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."
What really surprises me is, despite this, so many physicists have jumped on the bandwagon.
This is because it is the simplest theory which fits available data. There are simpler theories, but they do not fit available data, and thus are of little value.
Average Slashdotters have been more skeptical of they dark matter theory than physicists, from what I've seen.
This is because average Slashdotters do not have even the beginnings of a clue about astrophysics, but think they are expert at every subject they ever heard mentioned on the internet.
No one would have a problem with the notion of such a God. It's when the God of all space and time starts setting bushes on fire and demanding that people vote Republican that people start to call bullshit.
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 and
http://scienceblogs.com/startswithabang/2009/09/dark_matter_part_i_how_much_ma.php. 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. 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!).