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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)."
I'm sorry, but "gravitational effects" won't sell popsci books. For the sake of our royalties, let's stick to dark matter.
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
I'm envious of anyone who actually understands anything the summary is talking about.
If you want news from today, you have to come back tomorrow.
Also there was that Galileo guy too.
(Must be all the espresso they're always drinking.)
There's no -1 for "I don't get it."
Does this explain the gravitational lensing in the Bullet Cluster?
This is the kind of theory that could have be viable prior to August 2006. When the gravity isn't pointing towards the baryonic matter, we have to postulate that there's some dark matter for the gravity to point to. Or, as Sean Carroll put it
The name "gravity" is prejudicial as it presupposes a connection between the alleged force and weight! "Intelligent Falling" is the preferred term.
ASCII stupid question, get a stupid ANSI
It's called Intelligent falling.
Well, THIS religious nutbar subscribes to the theory that gravity is really just the love felt between particles: just as absence makes the heart grow fonder, distance increases this attractive force, resulting in increased orbital velocities of stars.
Love makes the galaxy go 'round.
my, your, his/her/its, our, your, their
I'm, you're, he's/she's/it's, we're, you're, they're
Nope. A theory which explains away the dark matter MUST explain the observable effects of: http://en.wikipedia.org/wiki/Bullet_Cluster Then it should explain discrepancy between small and large galaxies.
Only after it passes these two tests it could be discussed seriously. Yet another "I can haz explain rotation curves!!!" theory is definitely not interesting.
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!)
"I've got rid of dark matter!"
Yeah. That's implausible. After carving up the turkey recently, the last thing left was the dark matter. Everyone seems to like the white matter better.
"National Security is the chief cause of national insecurity." - Celine's First Law
I don't understand why this theory is "implausible" and why the article is so dismissive of it. Dark Matter was created for the sole purpose of explaining the orbital momentum of stars. There is NO other evidence for it.
There is lot of other evidence for non-baryonic Dark Matter:
* Lack of MACHO gravitational lensing
* Existence of unexpected gravitational lensing in Bullet Cluster.
* CMBR measurements
* and more.
It isn't hard to modify equations to match the galaxy rotation curves, and if that was the only evidence for dark matter it wouldn't be so strongly favored.
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.
Translation: "I'm not bright enough to think about orbital dynamics, so I'll just try to start an offtopic religion-bashing troll thread instead."
Indeed, stupid scientists made a big complicated theory about forces proportional to masses and then after doing experiments and finding that things fall the same regardless of mass, they cover up their error by adding even more factors!
Occam's Razor requires us to believe that stuff all falls at the same rate because God decided that was the best rate.
Why this rate? When God created the world, He made the rate of fall exactly enough that we could walk on two legs, while all Lower creatures cannot because the Falling Speed is not tuned for them. If Falling was even slightly slower or faster, your feet would hit the ground out-of-step and would not be able to walk - co-incidence? No, proof that God made the world for Man.
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.
I don't understand why this theory is "implausible" and why the article is so dismissive of it. Dark Matter was created for the sole purpose of explaining the orbital momentum of stars. There is NO other evidence for it.
False. So completely and entirely false that I really can't see you being anything other than a troll, but on the theory that sufficiently advanced ignorance is indistinguishable from malice, I'll point out what several others have already done above: the Bullet Cluster, various details of the CMB, and at various aspects of large-scale structure in galaxy clusters, up to and including the closure of the universe itself, are all evidence for Dark Matter of various kinds.
So all you've done here is declare, "I am completely ignorant of almost all of observational cosmology and THIS is my opinion on Dark Matter..."
After reading the first half of that sentence no one who knows anything about Dark Matter is going to be the least bit interested in what you have to say in the second half.
Blasphemy is a human right. Blasphemophobia kills.
Theories trying to handwave dark matter seem to pop up about once a month these days
Can you blame them? We found a bunch of stuff that doesn't fit our model for how the universe works so instead of invalidating our model we just assume that there is something invisible influencing our numbers. I won't pretend like I know what is really going on but blaming some undetectable third-party when your model fails feels like grasping at straws to me.
I just want to say- what little I do know, I've always disliked dark-matter. It always seemed to be a case of "we can't explain 'x' - so let's claim there is dark-matter and that will make our hypothesis match what we observe."
But you should realize that this technique has been used throughout the entire history of modern science, and its track record is actually quite good.
Back in the late 1700s, after the discovery of the planet Uranus, astronomers made careful calculations of its orbital elements and published a table the position of the planet in the sky over the years (and decades). As the years (and decades) wore on, they discovered a curious thing: the actual position of the planet was beginning to diverge from what had been predicted.
At this point, there were a few different explanations:
1) Perhaps the initial orbital elements were incorrect.
2) Perhaps our fundamental laws of gravity and motion were incorrect.
3) Perhaps there was a massive, as-yet-undetected eighth planet whose gravity was influencing the orbit of Uranus.
Most astronomers fell into the third camp; after all, the observations of Uranus's orbit had been made with considerable precision (for the time) and there was little reason to believe that the fundamental laws of physics would start to break down as you move further away from the sun. And so they made their calculations and narrowed down the location of this hypothetical planet to a fairly small window in the sky. After that, it was just a matter of pointing a telescope there and looking.
This is the story of the discovery of the planet Neptune.
Astronomers did not find this planet by accident. It was not discovered by a kid in the backyard with a streak of cosmic good luck. (In fact, many observers from antiquity had seen it, but had not realized what they were looking at.) They found it because they knew it had to be there.
Now, you might think that this comparison is a bit of a stretch. But it's just one example; there are countless more. Back in 1930, Wolfgang Pauli was studying beta decay in atomic nuclei. He realized that the process, as he was seeing it, could not possibly be happening unless there were (again, hypothetical) particles being emitted as a consequence. If there were not, then all sorts of fundamental principles of physics were being violated (e.g., conservation of matter / angular momentum / etc.)
This particle, eventually named the "neutrino", remained hypothetical and undetected for more than a quarter of a century until it was finally detected -- in 1956.
I could go on, but the point is that postulating the existence of something hypothetical in order to explain deviations between theory and observed results is part of the best traditions of natural science. It's not hand-waving or charlatanism. And it works more often than most people might think.
We're going down, in a spiral to the ground
You jest, but
http://en.wikipedia.org/wiki/Naval_Battle_of_Guadalcanal#First_Naval_Battle_of_Guadalcanal.2C_November_13
Hail Eris, full of mischief...
E pluribus sanguinem
When God created the world, He made the rate of fall exactly enough that we could walk on two legs, while all Lower creatures cannot because the Falling Speed is not tuned for them. If Falling was even slightly slower or faster, your feet would hit the ground out-of-step and would not be able to walk - co-incidence? No, proof that God made the world for Man.
Finally the long awaited proof that Ostriches are the work of the devil!
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!
"Athiesm takes as much of a leap of faith as belief in a diety or dieties"
Yes. And not collecting stamps is as much of a hobby as collecting them.
"It's sad how so many athiests think religion is anti-science"
Maybe because, well, it is. While science can't accept the 'argumentum ad auctoritatem', it is the only valid one for (theist) religion.
"if they don't believe in a diety why do they even mention one?"
It might be because people like you don't stop talking about it.
I'm going to nitpick your nitpicking, because there's some really objectionable stuff in it.
Oh, come come -- this is a story about how many of us scientists don't just believe in invisible tea-sets in space (Russell's accusation of religion), we believe there's more invisible tea-sets (dark matter) than visible matter!
That's ridiculous. Russell's tea-set analogy was to illustrate how a person who believes in religion does so without any positive evidence or reasoning. The hypothetical believer in space teapots believes in them in spite of the fact that not only have none been found wandering about the solar system, there's no reason to expect them to be present in the first place.
Dark matter does not fit that criticism in any way. It's an attempt to explain an interesting conundrum:
1. We think we know a lot of physics. Relativity and quantum theory aren't unified, but they each work very well in their respective domains.
2. We've been finding that there isn't enough visible mass (where by visible I mean "in the electromagnetic spectrum", not just the human range of visibility) to account for the observed gravitational interactions between many cosmological objects.
Dark matter is one possible answer for this problem. There might be matter which is hard or impossible to observe via EM spectrum emissions, so the only way we can notice it at cosmological distances is its gravitational influence on other matter. This is in no way analogous to Russell's teapot, because it is a hypothetical explanation for an observed fact, not a context-free irrational belief in a ridiculous notion.
And bet millions of dollars of research funding on that belief. While the chap who's saying "maybe there's no dark matter" is fighting an uphill battle.
This is nonsense, because the "maybe there's no dark matter" side has in fact been able to get funding. So far the "there's probably dark matter" side seems to be winning. That doesn't mean there's a religious belief in DM, just that it seems to fit the observable facts reasonably well, while the alternate theories proposed to date (modifications of existing physics, such as MOND) have generally failed to pass basic smell tests (such as whether they can reproduce well known experimentally verifiable phenomena).
"It is also what you would see if the majority of the dark matter is MACHOs"
No, it's not. In the bullet cluster all the regular, baryonic matter we can see (which is not just stars but also gas and dust) shows a drag effect. By looking at gravitational lensing we know that the majority of the matter actually does NOT show this drag effect. The majority of the matter in the cluster is behaving as if it doesn't interact with anything, except through gravity.
MACHOs definitely do interact through forces other than gravity, and behave just like baryonic matter (because they ARE baryonic matter). You're sitting on one, after all.
Hopefully this helps you understand where the idea of 'dark matter' came from. (Hint: arses don't seem to be an element.)
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