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 Posted: 18 Jan 2016 05:14 Post subject: air max 2016 all black |
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No sign of dark matter in underground experiment
A US team that claims to have built the nike mens free shoe 5.0 neon yellow world's most sensitive dark matter detector has completed its first data run without seeing any sign of the stuff.
In a webcast presentation today at the Sanford Underground Laboratory in Lead, South Dakota, physicists working on the Large Underground Xenon (LUX) experiment said they had seen nothing statistically compelling in 110 days of data taking. "We find absolutely no events consistent with any kind of dark matter," says LUX co spokesman Rick Gaitskell, a physicist at Brown University in Providence, Rhode Island.
Physicists know from astronomical observations that 85% of the Universe's matter is dark, making itself known only through its gravitational pull on conventional matter. Some think it may also engage in weak but detectable collisions with ordinary matter, and several direct detection experiments have reported tantalizing hints of these candidate dark matter particles, known as WIMPs (Weakly Interacting Massive Particles). Gaitskell says that it is now overwhelmingly likely that earlier sightings were statistical fluctuations.
LUX contains more than 300 kilograms of liquid xenon held 1,480 metres underground at the Sanford lab, where rock shields it from the confounding effects of cosmic rays striking Earth's surface. The hope is that dark matter particles, passing through Earth, will occasionally hit xenon nuclei, causing flashes of light that can be picked up by the experiment's 122 photomultiplier tubes, situated in arrays above and below the xenon. But only 160 events were seen, a level Nike Air Max 2016 Mens consistent with background nike air max 2015 mens black levels of radioactivity from the materials making up the experiment, and well short of what would be expected if candidate dark matter particles seen by previous experiments were real, says Gaitskell.
LUX has now set a limit on dark matter particle interactions that is two to five times more stringent than its closest rival, an experiment called XENON 100 in Gran Sasso National Laboratory near L'Aquila, Italy. In 2011, XENON 100 also saw no evidence for dark matter, but had been criticized for not being sensitive enough to very low mass dark matter particles tentatively reported by other experiments. LUX has five times the sensitivity of XENON 100 in the low mass realm, which should allay those concerns, says Gaitskell.
Despite the no shows at XENON 100 and LUX, Laura Baudis, a physicist on XENON 100 at the University of Zurich in Switzerland says physicists are not ready to give up on the idea of detecting WIMPs. They may simply have a lower mass, or may be more weakly interacting than originally hoped. "We have some way to go," she says.
Baudis adds that LUX's results may help the US$10 million experiment to win further funding. The LUX team hopes to scale up to seven tonnes of xenon in an $30 million upgrade called LUX ZEPLIN. The US Department of Energy is currently deciding which of three experiments to fund: LUX ZEPLIN; an upgrade to solid state silicon detectors called the Super Cryogenic Dark Matter Search, to be based initially in the Soudan mine in Minnesota; and an argon based liquid detector called DarkSide, also at Gran Sasso.
Juan Collar, a dark matter physicist at the University of Chicago in Illinois, agrees that LUX's solid results will boost its chances of being selected. On the other hand, he says that it would be more strategic for the Energy Department to fund one of the other two experiments, because they would develop other detection materials; European governments and the US National Science Foundation have already agreed to upgrade XENON 100 to the one tonne level. More than one large scale xenon experiment may not be necessary, Collar says. Shaw's experiment on the relation of temperature and gravity in nike mens free shoe 5.0 neon yellow a Cavendish type experiment. Many of the readers were alarmed about his result. In the late 1990's A Dmitriev confirmed Shaw's work and further found that a heated test mass changed its weight.
I have gotten a much greater change of weight with the use of"coldness" in addition to the use of heat.
No one wants to think about the possibility that that it may not be some mysterious property of the sun's mass that attracts the planets but rather the great amount of radiation (energy) that emanates nike mens air jordan 11 retro blue from it. . Someday we are going to have to face "horror the horror" about what we have erroneously believed about gravity for the past 300 years. Let's hope it not going to be as long as 1500 years it took to drop the similarly unphysical notion of geocentrism.
2013 10 30 05:25 PM
4.9% ordinary matter, 26.8% dark matter, 68.3% dark energy" 27% of the CMB universe is missing. Explain the Tully Fisher relation absent dark matter. MoND's Milgrom acceleration is universal for spiral galaxies, but has no. source.
Massless boson photons detect perfect vacuum mirror symmetry. Theory postulates this is exactly true for matter, then suffers symmetry breaking chaos. Matter experiences trace chiral vacuum anisotropy. Noetherian [exact vacuum isotropy] then [angular momentum conservation] leaks for matter as Milgrom acceleration, ending dark matter. Opposite shoes trace chiral vacuum embed (mount a left foot) with different energies. They vacuum free fall along divergent minimum action trajectories, exhibiting Equivalence Principle violation.
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