Science in Society Archive

No Dark Matter Detected Yet

Desperate search for dark matter with increasingly sensitive detectors has yielded nothing so far; maybe it never existed except in the standard theory of cosmology Dr. Mae-Wan Ho

A new high accuracy calibration of the LUX (Large Underground  Xenon) dark matter detector’s sensitivity to ultra-low energy events strongly confirms the result that it did not find low-mass dark matter particles during last summer’s initial run [1].

Dark matter is thought to account for about 80 percent of the mass of the universe, and without its gravitational influence, galaxies and galaxy clusters would simply fly apart.

No one knows what dark matter is but the leading idea is that it consists of subatomic particles called WIMPs, weakly interacting massive particles, thought to be practically ubiquitous in the universe, but because they interact so rarely with other forms of matter, they are hard to detect. LUX is designed to detect those rare occasions when a WIMP does interact with other forms of matter.

The LUX detector, buried more than a mile underground at the Sanford Underground Research Facility in South Dakota, is shielded from cosmic rays and other radiation that might interfere with signals from WIMPS. It consists of a third of a ton of supercooled xenon in a tank fully bugged with light sensors, each capable of detecting a single photon at a time. As WiMPs pass through the tank, they should on rare occasions bump into the nucleus of a xenon atom and create a tiny flash of light that could be picked up by the sensors.

The first dark matter search results from the LUX detector were announced in October 2013. The detector was exquisitely sensitive, but found no evidence of dark matter during its first 90 day run. This contradicted previous experiments that had detected potential signatures of dark matter particles with very low mass. The latest work focused on demonstrating the high sensitivity of LUX to potential signals.

“The new calibration improved our calibration accuracy by about a factor of 10”, said Rick Gaitskell, professor of physics at Brown University. “It demonstrates that our first dark matter search result, which showed no sign of low-mass particles, is absolutely robust.”

To calibrate the detector, the researchers used neutrons as a stand-in for WIMPs. The recoil created when a neutron hits the nucleus of a xenon atom is thought to be very similar to that created by a WIMP. The low mass neutrons were fired directly into the detector and the characteristics of the neutron recoil were measured by the detector’s instruments. They then went back to their data from the dark matter search to see if similar events had occurred.

Their initial results were confirmed: there were no low-mass WIMP events. Along with the low-mass WIMPs, the first 90 day run ruled out a swath of possibilities for what dark matter could be made of. “There are literally thousands of models of particle physics lying bloodied in the gutter,” Gaitskell said.

LUX will expand its search later in 2014 in a second, year-long run at an even greater sensitivity.

The results were presented 19 February 2014 at the Lake Louse Winter Institute in Alberta, Canada, by James Verbus who led the new calibration work.

Just over a week later, scientists running the Cryogenic Dark Matter Search (CDMS) experiment announced they shifted the border of this search down to a dark matter particle mass and rate of interaction that has never been probed, to as low as possible [2].

The CDMS scientists have cooled their detectors to very low temperatures to look for the very small energies deposited by the collisions of dark matter particles with germanium. The detectors are half a mile underground in a former iron ore mine in northern Minnesota, shielded from cosmic rays. The LUX experiment ruled out a wide range of masses and interaction rates above 6 GeV, CDMS carves out the territory below that level.

Three other experiments are searching for low-mass dark matter particles – DAMA (Dark Matter in Italy), CoGeNT Dark Matter Experiment at Pacific Northwest Laboratory in the US, and Europe’s CRESST project – and all claim that their data are compatible with the existence of dark matter particles between 5 and 20 GeV. But these are hard to pin down, as the lower the energy involved, the more likely they are to be overwhelmed by background noise. Even more troublesome is the fact that scientists don’t have a clue as to whether dark mater particles interact in the same way in detectors built with different materials such as germanium, argon, xenon, silicon, in more than a dozen experiments around the world.

All that can be said is that the sensitivity of these experiments is increasing by an order of magnitude every few years.

Some conventional scientists are already seriously considering the possibility that [3] “dark matter might not exist”; as many distinguished cosmologists and astrophysicists have been saying for years. One main contender for Big Bang theory is the Electric Plasma Universe [4] (see Continuous Creation from Electric Plasma versus Big Bang Universe, SiS 60). Another, at a more fundamental level, is E-Infinity fractal spacetime [5] (E-Infinity Spacetime, Quantum Paradoxes and Quantum Gravity - Story of Phi Part 6, SiS 62).

Article first published 14/04/14



References

  1. “LUX confirms it has not found dark matter”, Science Blogging Science 2.0, 20 February 2014, http://www.science20.com/news_articles/lux_confirms_it_has_not_found_dark_matter-130156
  2. “CDMS result covers new ground in search for dark matter”, MIT News, 28 February 2014, http://web.mit.edu/newsoffice/2014/cdms-result-covers-new-ground-in-search-for-dark-matter.html
  3. “Dark matter might not exist”, The Daily Galaxy, 8 February 2014, http://www.dailygalaxy.com/my_weblog/2014/02/dark-gravity-dark-matter-might-not-exist-todays-most-popular.html
  4. Ho MW. Continuous creation from electric plasma versus Big Bang Universe. Science in Society 60, 20-25, 2013.
  5. Ho MW. E-infinity spacetime, quantum paradoxes and quantum gravity – story of phi part 6. Science in Society 62 (to appear).

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There are 2 comments on this article so far. Add your comment above.

paul van Loon Comment left 29th April 2014 09:09:18
I'm sure that you already are aware of the following but in the off chance it hasn't come to your attention: www.thunderboltsproject.info I found that many scientific magazines have a polarized view which is far from fair. They stick to the model wherein gravity is to explain everything but fail to see the many anomalies and flaws in this popularized model. Probably because of the exotic consequences (the end of: the Big Bang model, black holes, dark matter, dark energy, neutron stars, redshift as a measure for speed and distance, the expanding universe, redshift and quasars as most distant objects (get informed about Halton Arp's carreer and quest)), and being afraid about carreers and reputations. I strongly suggest scientist are left to explore without having to answer to coorporate economics and are left free to investigate even the most obscure, in order to bring back purity and above all: awareness for all mankind. And, that those with different scientific approaches and angles are not obstructed in publishing their findings. It happens on a larger scale than I ever imagined and is the death for any science. With respect: Paul van Loon The Netherlands

Nancy Swanson Comment left 22nd May 2014 20:08:02
The only logical conclusion that I can see is that gravity doesn't exist. I have postulated that perhaps what we perceive as gravity is simply the pressure of the aether. Hendrik Lorentz and Henri Poincare developed the length contraction velocity transformations in an effort to preserve the aether. They showed that, because of length contraction, it was impossible to measure the aether using an apparatus such as Michelson & Morley used because the apparatus itself would be altered during the  experiment. Einstein did not say the aether does not exist, he merely said we don't need it to explain light propagation as long as we assume that the speed of light is constant for all observers. He then   used Lorentz's transformations as descriptions for his theory of Special Relativity. Einstein simply dodged the question of the existence of the aether. The rotating of a large mass would cause a warp in the aether (Einstein's General Theory of Relativity--the warping of space-time near a massive object). The warp from one massive object interacts with the warp caused by another. The resulting interaction is what we think of as gravity. I have always wondered why scientists continue to think of gravity as a force. Einstein's warping of space accounts for the phenomenon, no forces needed. Einstein never really explained how mass accomplishes this feat. The only thing I have added is the idea that space is not nothing. Matter is simply confined energy. If anything is nothing, it is mass. The real something is the aether.

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