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New Theory Challenges Need For Dark Matter
New submitter elsurexiste writes "An Italian Physicist came up with a strange way to explain anomalous galactic rotations without dark matter, instead relying on the gravitational effects of faraway matter. The article explains, 'Conceptually the idea makes little sense. Positioning gravitationally significant mass outside of the orbit of stars might draw them out into wider orbits, but it’s difficult to see why this would add to their orbital velocity. Drawing an object into a wider orbit should result in it taking longer to orbit the galaxy since it will have more circumference to cover. What we generally see in spiral galaxies is that the outer stars orbit the galaxy within much the same time period as more inward stars. But although the proposed mechanism seems a little implausible, what is remarkable about Carati’s claim is that the math apparently deliver galactic rotation curves that closely fit the observed values of at least four known galaxies. Indeed, the math delivers an extraordinarily close fit.' As usual, these are extraordinary claims that divert from the consensus, so keep a healthy skepticism. The paper is available at the arXiv (PDF)."
faster than light neutrino measurements?
revolutionary-yet-pseudo-sciency sources of energy?
and now dark matter challenges?
coincidence or what?
https://www.accountkiller.com/removal-requested
Disclaimer: I do experimental searches for dark matter for a living, so I may be biased in my judgement of these types of papers that crop up so often. There was a similar paper a few weeks ago from someone claiming that quantum vacuum polarization could account for dark matter PhysOrg link.
The issue with both of these explanations, is that they only address galactic rotation curves. Those are among the first and easiest to explain indications of the need for something like dark matter, but are not the strongest by a long shot. For instance, this guy's explanation can't explain things like the famous Bullet cluster , nor can they explain the evolution of structure formation or the spectrum of fluctuations in the cosmic microwave background which, in the field, are considered much stronger constraints.
The Cold Dark Matter (CDM) theory of cosmology fits all of the astrophysical measurements reasonably well, and has a nice tie-in to supersymmetric particle physics, which is one of the current leading theories. No one in the field will take any new theory seriously until it can reproduce ALL the phenomena at least as well as the current model (which of course is exactly how the scientific process is supposed to work!)
This is based on Einstein's field equation using perturbation theory to construct a solution for the examined case.
My bet is on general relativity once again delivering the goods. Quite a strike against the case for dark matter.
Seriously, is that the most you can add to the conversation is a cheap shot at religion?
It wasn't a shot at religion, it was a shot at religious fanaticism. There's a difference, and pretending otherwise is disingenuous at best.
I will agree that if such a claim is made it should be picked apart but can we just hold off the hostilities until it happens? For once?
Hostilities were opened a long time ago. Your objection makes as much sense as saying to the captain of a US Navy ship, "I agree that if that Japanese ship over there shoots at us, we should blow them out of the water, but can we just hold off the hostilities until in happens?" in 1943.
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
Just show the math and how it correctly models modern astronomical data.
I'll give you a hint, it doesn't even come close.
If someone is passing you on the right, you are an asshole for driving in the wrong lane.
The MACHO-based argument is that there can't be enough of those objects around in order to explain galactic rotation. But this paper, in effect, says that you don't need them. So that observation seems consistent with this paper.
The Bullet Cluster result shows that some form of unobservable matter exists. But we already know that: brown dwarfs, rogue planets, etc.: that kind of "dark matter" has been observed, just not in the amounts to explain galactic rotation.
It is not surprising that somewhere in the universe, you might get very large clusters of such objects. The bullet cluster might just be composed of such objects. And at those distances, you couldn't observe baryonic dark matter. In fact, if you rip out most of the hydrogen from a cluster, it is perhaps not surprising that you end up with a lot of cold, dark lumps of baryonic matter.
You have to separate explaining observations from testing hypotheses. CMBR measurements can be explained within the framework of non-baryonic dark matter. But that does not necessarily imply that they provide evidence for non-baryonic dark matter, since there are many other possible explanations.
I'm not saying that this paper is true or not. But if you want to argue against it, you need to sharpen your arguments.
Not sure about the summary, but the paper is extremely simple. I'll summarize it:
It is commonly assumed that galaxies are evenly distributed. This would mean that if you picked any galaxy at random, you could pick other galaxies whose gravitational pull totally balanced out the effect of the first one. So, overall, no distant galaxy would ever affect anything.
What is observed is that galaxies are NOT evenly distributed. There is, indeed, left-over gravitational pull. Provided the distribution of galaxies is self-similar (which is what they mean by "fractal", since "fractal" itself has no meaning here) AND a few other constraints are valid, THEN the left-over gravitational pull would be enough to explain the rotation of the stars and gasses within the galaxy. The author's analysis of the galaxies over a relatively nearby region of space suggests to him that the distribution is indeed self-similar.
(Summary off, analysis on)
Is this a new theory? As a replacement for Dark Matter, yes. In any other context, no. Shepherding moons/asteroids dominate our own solar system, creating a dynamic that would be utterly unstable without them. Shepherding galaxies and super-galaxies is a new one, but if the physics is observed in other systems then the physics must be considered sound. The only question I see here is whether the distribution of galaxies is indeed self-similar. If it isn't, the theory is wrong. If it is, then dark matter - as it is currently understood - must be wrong because you now have left-over gravity and you have to alter the dark matter theory to allow for it.
Doesn't the dark matter theory fit things well as it is? No it doesn't. Dwarf galaxies and globular clusters exhibit NONE of the signs assumed to indicate the presence of dark matter. Some don't have high-speed rotation at all. Dark matter theory cannot explain either of these and the usual answer is to say that dark matter "isn't uniform" without ever explaining why it should be missing only with certain classes of structure and not others. It's actually much easier to say that "excess" rotational velocity is a function of residual gravity and that where you have little residual gravity you have no excess rotational velocity. It is also entirely plausible to argue that "null points" are backwaters and that this explains why you get relatively few major galaxies appearing at such points but do get minor multi-stellar structures.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Odd how the fanatical, radical athiests get away with trolling so easily, and sometimes get modded up. Athiesm takes as much of a leap of faith as belief in a diety or dieties.
That's "deity". And atheism requires no leap of faith. Just the opposite, it's a lack of faith in things which require faith.
More if you've actually experienced a diety.
Nobody has. Yes, I know you'll probably claim you have, but I don't believe you. Religious nutters always love to talk about how their relationship with god has transformed them, but on closer examination the supposed relationship is always rather distant, so much so that the most plausible explanation is that the nutter is inventing it in his or her own mind. We know enough about human psychology to understand how the mind can delude itself into creating a relationship with a being that doesn't really exist.
It's sad how so many athiests think religion is anti-science, and how they somehow think that you can have science or religion but not both, when over half of scientists are in fact religious.
It's sad when anyone otherwise dedicated to science decides to compartmentalize their mind so they don't insist on the same standard of proof for the existence of god as they do everything else. But not unexpected given that scientists are members of society, and society is soaked in god delusions.
Nevertheless, scientists are significantly more atheistic than the general population. To be successful at science, you must at least partially integrate the logical, empirical view of the universe which is the backbone of science. Anyone with that philosophical orientation who also allows God out of that don't-think-about-this-logically mental compartment quickly notices that science has eliminated the need for a god to explain anything, and how laughable the evidence for every human religion is. This is a fast track to atheism, or religious-in-name-only (identifies as religious, but doesn't really believe, attends services irregularly for social value and lingering love of the ritual).
You don't have to be a bona fide trained scientist to notice those weaknesses either. I deconverted from Catholicism because the religious and scientific instruction in their own schooling got me to notice what a shaky foundation the religion had. (I include the religious instruction because so much of it was concerned with how much better and more logical Catholicism was than other religions, yet it was easy for me to see through the apologetics and realize that the criticisms actually cut both ways.) 20+ years later, with a much more sophisticated understanding of all the issues I first explored at age 13, I still have not found a reason to believe in any god.
I wish everyone would stop the damned trolling. It annoys me and detracts from slashdot. This thread is no place for a religious discussion. And if they don't believe in a diety why do they even mention one?
Oh noes mcgrew can't handle that other people disagree with him about the existence of his magical sky daddy. He wants unearned hands-off don't-go-there respect, the respect religion has gotten for millenia just because It's Religion! And therefore Untouchable!