LOWER DOWN: XENON100 scientists Roberto Santorelli, Elena Aprile and Guillaume Plante [from left] during the detector's installation in 2008.
Image: Courtesy XENON100 Collaboration
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Gravity's Engines
We’ve long understood black holes to be the points at which the universe as we know it comes to an end. Often billions of times more massive than the Sun, they...
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An experiment looking for the signal of dark matter deep in an underground lab in Italy turned up no candidate signals in 11 days of early operation, the experimental collaboration reported in a paper posted online Monday. The underground detector, called XENON100, only recently began taking data but is already challenging prior claims and hints of dark matter signals, according to the team, which published its findings on the physics preprint repository arXiv.org.
XENON100 is one of a number of cryogenic underground detectors designed to sense subtle recoil effects expected to be induced by the rare collision between passing dark matter particles and the atoms of the detector material (liquid xenon, in this case). Dark matter is the stuff that has long been invoked to explain the disparity between how things look and how they behave at the largest scales of the universe—galaxies within clusters, for instance, move as if they contain far more mass than they appear to have. A wealth of evidence supports the notion that atoms and molecules represent only a fraction of the gravitationally interacting mass in the universe.
Direct detection of dark matter particles, however, has proved elusive—and contentious. Researchers working on an experiment known as DAMA (short for dark matter), which occupies the same subterranean Italian laboratory as XENON100, have for years claimed that they have identified dark matter by spotting annual fluctuations as Earth moves through its orbit—and, presumably, through the halo of dark matter particles enveloping the Milky Way.
With its high sensitivity, XENON100 should have seen something if the DAMA interpretation were correct, the experimental collaboration contends. Brown University physicist Richard Gaitskell, who works on the larger xenon-based dark matter detector LUX (Large Underground Xenon), which he expects will be installed underground in South Dakota next year, says the DAMA results have not been borne out by other searches. "It has been very difficult to obtain any results which support the interpretation of the DAMA experiment as particle dark matter," Gaitskell says.
Massachusetts Institute of Technology physicist Peter Fisher says that procedural questions have also clouded the claimed detection. "The DAMA collaboration has been, to say the least, difficult to deal with," Fisher says. "People have asked many questions about their apparatus and data quality checks, and they are not forthcoming. This has led people, to some extent, to discount their results."*
Late last year another research group in the chase announced an interesting signal as well. Physicists working on CDMS, an underground detector in Minnesota, said in December that they had registered two potential hits from dark matter. At the time they took care to note that the "results cannot be interpreted as significant evidence" of such interactions and that either or both could have been background noise. "The fact that they saw two events is very likely a simple statistical fluctuation in that background," Gaitskell says. "This is the most likely explanation."
The dark matter hunt is still wide open—and, as Fisher predicted last month in a public lecture, "the person who finds it is going to get a quick trip to Stockholm," where the Nobel prizes are awarded.
Gaitskell says that the early XENON100 data bode well for the new generation of large detectors based on the inert liquid, including his own project that is now nearing realization. "In just 11 days of exposure they have been able to match the sensitivity of CDMS, which needed in excess of 12 months of data for the same dark matter search sensitivity," Gaitskell says. "For comparison, the larger LUX detector will reach the same sensitivity in less than 36 hours."
*Update (4:20 P.M.): This paragraph was added after initial publication.
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35 Comments
Add CommentFound any phlogiston lately? Neither have I.
Reply | Report Abuse | Link to thisSeek and ye may find, sit around and mock and ye will never find anything.
Reply | Report Abuse | Link to thisIs Dark Matter hiding in plain sight. Consider...Attraction exists between all things and, in any given circumstances, its strength between any two things depends exactly on the amount of mass in each. So exact that its source must be the smallest, indivisible bit of mass there is. Some of those bits combine into units around which others orbit in regular frequencies and amplitudes, which we detect with our instruments that are sensitive to those movements. Other basic bits of mass don't move in such regular patterns so we don't detect frequencies, etc. but they still attract and we detect their presence from the effects of that attraction. Visible and dark matter would be the same stuff. Its their motions that are different. Also, the reason for the attraction need not necessarily be as much a stretch as some posit.
Reply | Report Abuse | Link to thisWhat is overlooked in almost all gravitational evaluations of large scale aggregations of massive objects is that gravitational 'binding' occurs at all scales. Unlike the planets in our Solar system, galactic stellar masses do not independently orbit a dominating central massive object. Galactic masses interact gravitationally as collectively bound objects. Please review the more complete essay/article,
Reply | Report Abuse | Link to this"Mass Distribution Characteristics Invalidate the Galaxy Rotation Problem"
posted at:
http://www.sciencewithoutfiction.com/uploads/Mass_Distribution-_Galaxy_Rotation_Problem.pdf
In the search of anti-matter (dark matter/energy) why are these things always in some far distant part of the galaxy? They claim that the universe is being pulled apart by the Dark Forces, if this is true would we, too, be bathed in the Dark Force? Would not the Dark Force be all around us and even in the blades of grass, the sky above and the space between me and my PC (keyboard, monitor, and my CPU)? Like the allusive Pimpernel, the allusive Dark Forces of Matter and Energy have to be tapped into by a trained Knight of the Jedi, maybe that is why our these detectors have not detected the Dark Force; one must be trained in the use of the Force. Do not try to tap into the Dark Force, for we are trained professionals and are trained in the use of the Force. May the Force be with you.
Reply | Report Abuse | Link to thisInteresting! So, "Dark Matter" essentially represents an invalid and unnecessary concept invented to justify erroneous results of misapplied gravitational laws...yes?
Reply | Report Abuse | Link to thisThe simplest foundation always supports the most configurations, simple to complex beyond our comprehension. Two energies, space compressed into points of compressed space surrounded by stretched space, from the same action, the latter pulling between any two of the former. Stretched space, Einstein's "bent/warped" space?
Reply | Report Abuse | Link to thismcguigtw - Very good - that's pretty much it. To fully elaborate, dark matter is the simplest method of providing the additional mass necessary to compensate for the erroneous results produced by the application of familiar centralized mass gravitational effects to a vast planar distribution of massive objects.
Reply | Report Abuse | Link to thisTo my knowledge, this was very first briefly noted in 2005 by Cooperstone & Tieu. Unfortunately their solution, based on the gravitational equations of general relativity, met with mathematical criticism from peer theoretical physicists, and has not been published.
I independently identified the problem in 2008. I can't offer a mathematical solution, but I do hope to make the problem well understood.
When are they going to to find out that out all this extra mass,and energy is made of space-time itself?.
Reply | Report Abuse | Link to thisThe reporting of the Minnesota findings almost invariably showed a very poor understanding of basic probability. There was a great deal of confusion between the idea that there was prior 25% probability of a spurious event and the posterior probability that an event was spurious after it had occurred. Bayesian analysis is the appropriate way to understand this. In effect the actual event told us next to nothing about dark matter but it did demonstrate the well known fact that even science journalists are dodgy on stats!
Reply | Report Abuse | Link to thisThere was a great deal of confusion between the idea that there was prior 25% probability of a spurious event and the posterior probability that an event was spurious after it had occurred. Bayesian analysis is the appropriate way to understand this. In effect the actual event told us next to nothing about dark matter but it did demonstrate the well known fact that even science journalists are dodgy on stats!
Reply | Report Abuse | Link to thisWell let's be realistic here. Astronomers can't have properly applied the gravitational laws because our mathematics can't handle large-scale many body problems.
Reply | Report Abuse | Link to thisTake a look at quantum mechanics, specifically the wave solution for a hydrogen atom, the simplest atomic construct that exists. If you throw in three extra protons and electrons, that same wave problem becomes almost hopelessly complicated because of the manifold interactions and perturbations the orbiting electrons create for each other. Trying to calculate the actual gravitic interaction between many stellar bodies is similarly hopeless - the methods astronomers have used to measure their interactions has always been one of very rough approximation. Is it any surprise their answers fell out of the ball park?
What does surprise me is that rather than owning up to the fact that they can't compute the forces acting withing conglomerations of this scale, they invented a mysterious undetectable source of matter and energy to explain the discrepancy.
Alas the infinities are found everywhere.There's simply no way to tie up the lose ends.
Reply | Report Abuse | Link to thisI predict that all experiments to find Dark Matter will fail. We should now be looking at theories on the structure of the universe itself that could account for it. One such theory is that the excess gravitational force is produced by gravitational leakage from parallel quantum universes. The Many Worlds interpretation has not been thoroughly examined for its implications.
Reply | Report Abuse | Link to thisbnblack - Pardon my intrusion, but there's no need to search for dark matter if you understand the origin of its hypothesis. I predict that dark matter can't be found because it does not exist. Please see:
Reply | Report Abuse | Link to this"Mass Distribution Characteristics Invalidate the Galaxy Rotation Problem",
http://www.sciencewithoutfiction.com/uploads/Mass_Distribution-_Galaxy_Rotation_Problem.pdf
I believe that underground detectors are wrong, that Dark matter is not going to be like neutrinos coming from outer space in large amounts. Dark matter only interacts by gravity with visible matter, so study the pull of the ocean tides to try and detect it. Quit wasting grants and taxpayers funds for mad scientist experiments. Study what exists here on earth, massive earth object pulled by earth gravity has same laws as our galaxy tidal streaming with 90% halo DM. Find it here not underground where the pull of gravity is the greatest!
Reply | Report Abuse | Link to thisDark matter in our sollar sysrem is so stongly organiozed by the Sun and its surface emmision activity that the theory-vague basis of our mearements and its realtive crudeness totally obscures ---we simply do not knot know what we are doing good enoutgh for descent scientic measure----it mearely peobaility type guessing as ooposed to deterministic guessing so the data obtained is in the noise level.
Reply | Report Abuse | Link to thisLike some others here, I too find the existence of DM to be extremely unlikely. I am wondering though, would the sensitivity of these eventually useless DM detectors be sufficient to detect perturbations arising from the mutual annihilation of hypothetical virtual particles?
Reply | Report Abuse | Link to thisI have an idea! Lets make something up and then see how much money we can get to try and detect it.
Reply | Report Abuse | Link to thisBe respectfull from one collaboration to the other. Be open for more points of view about dark matter (and dark energy). Note, that the arXiv archive is not a holy archive. There are more options among researchers (theoretical and practical). In particular arXivs policy needs to be changed by accepting submission from independent scientists, without two institutional affiliated scientists being a backup for submissions. Also Scientific American is often neglecting fresh ideas. Editors of science-magazines have often too much ego to allow new ideas from insiders and outsiders. They do not scan the internet enough to inform themselves about other options. So, let me inform those who understand this. There is a new theory of dark matter-dark energy: The double torus universe, officially called the "Twin-Toricosmological Model". The appropriate papers are to be find in the alternative archive: "viXra". The weblinks to the papers are available on my website. The model introduces a "new dark energy force formula", an "intermediar force" between a torus of dark energy, which is enclosing a torus of dark matter. In the dark matter torus 4% visible matter is located. There is already evidence for the "double torus". There is also a mathematical underground available.
Reply | Report Abuse | Link to thisDan Visser, independent cosmologist, Almere, the Netherlands; website: www.darkfieldnavigator.com; contact: dan.visser@planet.nl
jimhensen - To entertain your line of reasoning for a moment, you are correct in that to maintain the presumption that the rotation of spiral galaxies must be consistent with the Keplerian Rotational Curve, dark matter must be about ten times more massive the visible galactic matter, and it must be located at the periphery of the galaxy's visible mass.
Reply | Report Abuse | Link to thisHowever, this standard dark matter model of galactic mass presumes that the gravitational effect is always centrally directed, which is not correct: it is directed to the locally determined collective center of mass. If the majority of mass was located at the galaxy periphery gravitation would also be directed to it. If the massive molecular clouds producing new stars are examined, proximal embedded stars do not more rapidly orbit their collective center of mass as required by the peripheral dark matter model.
To understand why dark matter was only envisioned to meet the invalid expectations of astrophysicists, please see "Mass Distribution Characteristics Invalidate the Galaxy Rotation Problem", at:
http://www.sciencewithoutfiction.com/uploads/Mass_Distribution-_Galaxy_Rotation_Problem.pdf
By the way, keep in mind that these particle hunters are experts in their field, specifically trained in the standard methods of detecting undetected particles. They've been working at this for many years, continually refining their techniques to raise new funding for ever more sensitive detectors. Please just let them do their jobs without all your criticisms - after all, if they find anything they'll be Nobel prize winners!
Reply | Report Abuse | Link to thisValjean;
Reply | Report Abuse | Link to thisOne assumption that you are making needs to be addressed; your are assuming that dark mater makes a gravitational field that attracts normal matter. Perhaps gravity has more than one axis. Perhaps gravity is not a force at all. I think that gravity is an effect of time distortion caused by energy. Time is one of the axis of energy and when you put enough energy in one spot then the time field warps generating a time rate change. This in turn generates the resultant perception of gravity. It also explains why gravity is mono polar and we have not yet discovered the theoretical Graviton.
If this is the case (and I admit this is a big IF) then if dark matter does exist it may not have the same effect on time (in that direction) and therefore may not produce the gravity field that you mention.
The more I read about quantum physics the more that it makes sense to me that gravity is not a real force like electromagnetism but an effect caused by time distortion. This effect and the illusion of space itself can be explained if you consider that force has a component of acceleration in it and that acceleration is the second derivative of position or perhaps it is more accurate to state that position is the double integral of acceleration. Acceleration is comprised of dv and dt. If dt shrinks then acceleration increases and we generate a force. We also generate space.
I know that this does not explain the additional attraction of the matter in the galaxies that cannot be explained by their visible matter but it may explain that there is an energy of sorts between the galaxies that is squeezing them together. This energy could be derived from a force that has an increase in dt therefore generating an apparent force that looks like antigravity. This would not only account for the missing matter but quite possibly the acceleration acting on the expansion of the Universe.
They are not 'making it up'. But science requires that you try to imagine the possibilities then explore those do prove or disprove them.
Reply | Report Abuse | Link to thisEinstien said that "Imagination is more important than knowledge".
@jtdwyer & galaxy_man, until that line of reasoning has been proven the door is still open to dark matter. As a modeller I personally don't agree that the "inability to solve" many body problems implies that we are unable to make accurate calculations about the dynamics of the galaxy. We make very accurate predictions concerning many body problems on a regular basis. The galaxy is large and relatively slow moving. That makes the problem much easier to solve. If all the stars were tightly packed and bouncing off each other that would certainly be more difficult. Still chaotic phenomenon do display large scale order so they too can be understood to a degree. But it depends what you are trying to do. Do you want to predict everyone's position in tx or do you want to know relative distribution? Different problems, different degrees of certainty.
Reply | Report Abuse | Link to thisScience is about probabilities. One of the frequent types of arguments I see here (on many subjects) is of the form, x can't be determined with absolute certainty, therefore all phenomenon that are affected by x are 100% unknowable. That is binary thinking. You either know it absolutely or you know nothing. The fact is, x may be calculated to a certain probability, therefore results that are affected by x are not invalidated but rather reflect that degree of uncertainty.
I've said it before and I'll say it again, if you think you have a simple solution to a complex problem that the experts have overlooked it generally means that you don't understand the problem.
robert schmidt - It's unfortunate that I'm incapable of providing adequate mathematical proofs or data analysis supporting these assertions. In the meantime, it seems most reasonable that the door remain open to this line of reasoning until the existence of dark matter has been physically proven by its detection, especially since accepted particle physics theories do not predict any such particle.
Reply | Report Abuse | Link to thisThe discrepancy between the velocities predicted by the laws of planetary motion, as applied by astronomers, and those observed have not been accounted for without the presence of an unpredicted and undetected form of massive particles. This is why the Galaxy Rotation Problem has been otherwise unsolved for 40 years.
Please let me know if you can refute specific assertions made in the essay "Mass Distribution Characteristics Invalidate the Galaxy Rotation Problem", at:
http://www.sciencewithoutfiction.com/uploads/Mass_Distribution-_Galaxy_Rotation_Problem.pdf
robert schmidt - Regarding your closing statement:
Reply | Report Abuse | Link to thisIn my >30 year career, I was often the outsider brought in to solve the most difficult, critical problems that eluded solution by the subject area experts. The most difficult problems are those in which established procedures are applied to new, inappropriate conditions, like applying planetary solutions to galactic conditions. The local experts, knowledgeable as they are, cannot find fault in the procedures applied. The most difficult problems are often those the experts simply misunderstand.
@jtdwyer, I doubt you were just brought in off the street to solve someone elses problem. You were likely brought in because your were an "expert" in a particular problem domain. I work in computers too and am called in to develop software for technical applications. Often times the client doesn't know how to properly express how they need the software to work. I am able to solve this not because I am an expert in their business but because I am an expert in mine which is abstracting business problems and respresenting those abstractions in code. Some kid who hacks WoW wouldn't be able to do what I do, or what you did and I assure you, you would be really annoyed if he started telling you how to do your business.
Reply | Report Abuse | Link to thisIn regards to your pet hypothesis, I wasn't saying that it should come off the table, I was just saying you can't count the dark matter hypthesis out just because you like yours more. As you stated, your hypothesis hasn't survived peer review, that tells me it currently does not have enough merit to stand on its own.
In regards to my reviewing the material; I spent a great deal of time modelling solar systems, local groups of stars and weather. I know what I don't know. I don't know enough to make authoritative judgements about any of these hypotheses. Neither do any of the people who posted their certainty that dark matter is dead, dying or in remission. Which is my point. If it takes researchers millions of dollars and elaborate equipment buried deep in the earth years to conclude that they still don't understand the phenomenon then I seriously doubt some armchair scientists surfing the net in their jammies can put the subject to rest.
robert schmidt - Feel free to doubt whatever you like, but I won't accept dismissal on grounds of non-accreditation.
Reply | Report Abuse | Link to thisNot to imply that I am a qualified physicist, but my extensive problem solving experience does include explaining to application as well as operating system developers and computer processor engineers why their designs are not functioning correctly, as well as suggesting specific design enhancements. I appreciate the difficulty of advising experts, especially those who are highly specialized and especially when there is little external demand for their correction of the problem, as in this case.
I am simply trying bring attention to what I think is the correct resolution of a fundamental problem. I would be delighted to receive serious 'peer' review of specific arguments from capable experts in gravitational evaluation. In the meantime, I will not be dissuaded by summary dismissals .
jtdwyer, I have read many of your posts, and ask if you can provide some information on your education, experiences and credentials to make some of the assertions you have. Just asking, Thanks in advance.
Reply | Report Abuse | Link to thisHubert Boyd - I find it curious that people are often more interested in my credentials than in discussing the assertions that I make. The short answer is that I have no credentials, but I never let that prevent me from solving critical problems.
Reply | Report Abuse | Link to thisI passed my high school general equivalency test while on fuel run to Cam Rahn, Viet Nam in 1971. I later tried university for a couple of months before attending a computer programming school for two months. I worked in information systems for 32 years before retiring as a Technical Fellow, IT Systems Planning after >25 years with one of the world's top corporations. For most of that time I was the principal performance analyst and capacity planner for one of the world's very largest and fastest growing computer facilities. I addressed critical problems in very large scale systems, managed equipment planning financing and implementation configurations. I simply worked hard to solve problems regardless of having no accredited qualifications for doing so. In business, the actual results are the final proof. While I have written many technical and financial business papers, I am not capable of producing an acceptable scientific argument.
I'm now old and lame, with little I can do. I guess I can't completely escape my compulsion to solve problems: I'm just hoping to offer a correct solution approach to someone who can develop an acceptable scientific proof and presentation.
Thank you for a most courteous and comprehensive reply.
Reply | Report Abuse | Link to thisHubert Boyd
If you think of the particles of matter in the universe as corresponding to an energy wave in the same way that photon particles correspond an EM wave you might come to a plausible answer to the dark matter question. Suppose the hypersphere of cosmic expansion is actually an energy wavefront and particles of matter appear where the wave amplitude is greater. First you get an explanation for cosmic expansion without a big bang. Second you get a plausible answer to something that exists between the stars that has the potential to hold them together. The amplitude of the energy wave between stars may be too little to have corresponding particles but it may be large enough to supply an additional force to hold stars together in galaxies.
Reply | Report Abuse | Link to thismarlowg - IMO, unlike sparse planets orbiting the central mass of the Solar system, galaxies are very simply held together by local interstellar gravitation. The loosely bound galactic mass rotates somewhat like a bound object of mass.
Reply | Report Abuse | Link to thisI do think that all material energy can and does manifest as both as an energy wave, dispersed through spacetime producing kinetic motion, and as a particle, localized in spacetime with its kinetic energy configured as the potential energy identified as mass. This kinetic/potential energy state duration seems to vary in proportion to particle's attributed mass, restricting distance traversed.
I suspect that the expansion of spacetime is produced by a nearly infinite wavelength or pulse of energy which it also disperses as it expands. I do not think of this as an energy wavefront on which matter surfs, but a continuum of space and time in which material energy is contained. But I'm just guessing, like everyone else.
Since I discovered in 2008, from the perspective of a retired information systems analyst, that the methods used in identifying the requirements for dark matter were faulty, I have been unable to provide a fully convincing argument for my case due to my limited mathematical abilities. My logical analysis is expressed in the essay "Mass Distribution Characteristics Invalidate the Galaxy Rotation Problem", posted at:
Reply | Report Abuse | Link to thishttp://www.sciencewithoutfiction.com/uploads/Mass_Distribution-_Galaxy_Rotation_Problem.pdf
I have recently been directed to a set of papers providing mathematical anlyses of those same faulty methods by Kenneth F, Nicholson, a retired engineer, going back to 2000.
"Errors in equations for galaxy rotation speeds"
http://arxiv.org/abs/astro-ph/0309823
"Galactic mass distribution without dark matter or modified Newtonian mechanics"
http://arxiv.org/abs/astro-ph/0309762
"Galaxy Mass Distributions from Rotation Speeds by Closed-Loop Convergence"
http://arxiv.org/abs/astro-ph/0303135
"Galaxy mass distributions for some extreme orbital-speed Profiles"
http://arxiv.org/abs/astro-ph/0101401
"Disk-galaxy density distribution from orbital speeds using Newton's law, version 1.1"
"http://arxiv.org/abs/astro-ph/0006330
"Disk-galaxy density distribution from orbital speeds using Newton's law"
http://arxiv.org/abs/astro-ph/0006140