Future

After Higgs Boson, The Spotlight Turns To Dark Matter

Now that scientists have uncovered the elusive Higgs boson particle, it's time for them to move on to another piece of the puzzle: the mysterious substance that fills one quarter of the universe - dark matter.

Mapping the invisible (NASA Goddard Photo and Video)
Mapping the invisible (NASA Goddard Photo and Video)

GENEVA – Now that light has been cast on a new particle that looks pretty darn like the mythical Higgs boson, it's time for Geneva's European Organization for Nuclear Research (CERN) to start a considerably more obscure quest: the ever elusive "dark matter."

The international particle physics laboratory released its first results last week – results obtained thanks to the famous particle accelerator, the Large Hadron Collider (LHC), but also thanks to the Alpha Magnetic Spectrometer (AMS) installed in May 2011 on the International Space Station (ISS). The initial results were revealed in the presence of the crew that put the AMS into orbit – that of the space shuttle Endeavour.

This project is part of a series of experiments whose goal is to identify the nature of the oh-so-enigmatic substance that fills about a quarter of the Universe.

In 1933, Fritz Zwicky realized that there was definitely something wrong with the sky. As he was trying to estimate the mass of the cluster of galaxies known as Coma Berenices, the Swiss astronomer noticed that said galaxies were rotating too fast around the center of the cluster, and should therefore be ejected – much like a child off a fast spinning carousel.

Unless – he assumed – there is something hidden in the cluster, a kind of heavy and stable additional matter, capable of using gravity to keep these "spiraling" galaxies together. The concept of dark matter was born. Now the only thing left to do was to find out what on earth this dark matter was made of.

Soon enough, several theories involving some of the most exotic ingredients known to scientists (including neutrinos) were suggested. To no avail. Clearly the dark matter, accountable for 22% of the universe -- five times more than the total of visible matter contained in all the galaxies -- was composed of "something else" of an unknown nature.

Identifying the galaxy's WIMPs

The latest explanation involves the very fashionable WIMPs, short for Weakly Interacting Massive Particles. These corpuscles weigh 10 to 10,000 times more than a proton, which means that if our galaxy is bathed in dark matter, identifying these WIMPs using advanced detectors should be possible. Various teams around the world have built a plethora of instruments (DAMA and Xenon in Italy, CoGeNT and CDMS in the U.S., Picasso in Canada, Zeplin in England, Edelweiss in France), each one working with an extremely sensitive crystal that spots any new corpuscular intrusion.

However, scientists know that their task is not an easy one: First of all, they believe that WIMPs could interact with their crystals about only once a year; then the "noise pollution" caused by cosmic rays and natural radioactive decay makes things even more complicated; so far, the experiments have led to conflicting results. A failure? "Quite the opposite: using better detectors, scientists have managed to narrow down the field of research," Professor Jules Gascon, a member of the French Edelweiss team, told the monthly French science magazine La Recherche. "The next generation of instruments will reduce it even more."

Maybe the problem lies somewhere else? Are they looking in the wrong place? According to research by the European Southern Observatory (ESO), dark matter is not homogeneously distributed in our galaxy. Some theories postulate that dark matter is present in such small quantities, in a 13,000 light-years radius around the sun, that it's nearly impossible to spot...

Researchers at the University of Michigan wrote in the international scientific journal Nature on July 12, that they thought the mysterious entity was lurking in filaments connecting clusters of galaxies. The astrophysicists came to this conclusion after studying two such clusters, named Abell 222 and Abell 223, located some 2.4 billion light-years away from Earth.

Other scientists therefore prefer to track down WIMPs indirectly, looking for clues of their existence. During the Big Bang, the elusive particles -- just like all the other particles -- were created together with their antimatter doppelganger: electrons were born with positrons, antiprotons with protons, and, similarly, with every WIMP an anti-WIMP appeared, just as invisible as its double.

What matters is that when these opposites meet, they annihilate each other, thus generating particles -- but this time, very tangible particles -- of matter and antimatter. These are the ones that physicists are stalking with the Alpha Magnetic Spectrometer, built partly at the CERN and partly at the University of Geneva, and installed on the ISS. "We're trying for example to discover whether there are sources of anomalous positrons in the universe," says Swiss physicist Martin Pohl.

Elusive super-particles

Meanwhile at the CERN, researchers not only track down traces of the elusive dark matter – they actually try to recreate particles, using the LHC! And physicists are all the more motivated since they apparently managed to get their hands on the Higgs boson. "This particle is the keystone of the Standard Model, that is, the most comprehensive theory to date," says CERN Director Rolf-Dieter Heuer. "In the coming months, we are going to study the boson's characteristics thoroughly. But if what we find doesn't correspond with our predictions, this means that there could be an even more general theory, which could include dark matter."

This even more general theory has a name: super-symmetry -- SUSY for short. It rests on the assumption that every particle comes with a mirror particle – the latter being much more massive; which means that for example, electrons are accompanied by their heavyweight counterparts called "selectrons'. These super-particles (hence selectrons' inital "s') may be the secret behind dark matter. But physicists think that if none have been observed so far, it's probably because today's instruments are not powerful enough to create them.

"We also know for a fact," says Rolf-Dieter Heuer, "that super-particles decay rapidly into lighter super-particles and into particles that we may be able to detect in order to reconstruct this kind of funneling effect," – the whole process being basically comparable to a set of Matryoshka dolls. "The thing is, the last of these nested super-particles cannot decay, it remains stable, and can be seen." Has it been seen? "Not yet, but perhaps we haven't looked at our data well enough..."

And although finding dark matter probably won't happen overnight, cheer up: things might get easier in 2015. At the end of 2012 the LHC will be shut down for maintenance and upgrades for up to two years. After that, physicists hope that they'll be able to work with twice as much energy as today, and thus generate particles with an increasingly high mass. Suffice it to say that the constituents of dark matter, if they exist, should start looking for a good hiding place... "It will take time and patience," warns Rolf-Dieter Heuer, "but it's obvious that with the LHC and the AMS, chasing the mysterious dark matter has become one of today's major scientific challenges. "

Read more from Le Temps in French

Photo – NASA Goddard Photo and Video

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Green

Ecological Angst In India, A Mining Dumpsite As Neighbor

Local villagers in western India have been forced to live with a mining waste site on the edge of town. What happens when you wake up one day and the giant mound of industrial waste has imploded?

The mining dumpsite is situated just outside of the Badi village in the coastal state of Gujarat

Sukanya Shantha

BADI — Last week, when the men and women from the Bharwad community in this small village in western India stepped out for their daily work to herd livestock, they were greeted with a strange sight.

The 20-meter-high small hill that had formed at the open-cast mining dumpsite had suddenly sunk. Unsure of the reason behind the sudden caving-in, they immediately informed other villagers. In no time, word had traveled far, even drawing the attention of environment specialists and activists from outside town.

This mining dumpsite situated less than 500 meters outside of the Badi village in the coastal state of Gujarat has been a matter of serious concern ever since the Gujarat Power Corporation Limited began lignite mining work here in early 2017. The power plant is run by the Power Gujarat State Electricity Corporation Limited, which was previously known as the Bhavnagar Energy Company Ltd.

Vasudev Gohil, a 43-year-old resident of Badi village says that though the dumping site is technically situated outside the village, locals must pass the area on a daily basis.


"We are constantly on tenterhooks and looking for danger signs," he says. Indeed, their state of alert is how the sudden change in the shape of the dumpsite was noticed in the first place.

Can you trust environmental officials?

For someone visiting the place for the first time, the changes may not stand out. "But we have lived all our lives here, we know every little detail of this village. And when a 150-meter-long stretch cave-in by over 25-30 feet, the change can't be overlooked," Gohil adds.

This is not the first time that the dumpsite has worried local residents. Last November, a large part of the flattened part of the dumpsite had developed deep cracks and several flat areas had suddenly got elevated. While the officials had attributed this significant elevation to the high pressure of water in the upper strata of soil in the region, environment experts had pointed to seismic activities. The change is evident even today, nearly a year since it happened.

It could have sunk because of the rain.

After the recent incident, when the villagers raised an alarm and sent a written complaint to the regional Gujarat Pollution Control Board, an official visit to the site was arranged, along with the district administration and the mining department.

The regional pollution board officer Bhavnagar, A.G. Oza, insists the changes "aren't worrisome" and attributes it to the weather.

"The area received heavy rain this time. It is possible that the soil could have sunk in because of the rain," he tells The Wire. The Board, he says, along with the mining department, is now trying to assess if the caving-in had any impact on the ground surface.

"We visited the site as soon as a complaint was made. Samples have already been sent to the laboratory and we will have a clear idea only once the reports are made available," Oza adds.

Women from the Surkha village have to travel several kilometers to find potable water

Sukanya Shantha/The Wire

A questionable claim

That the dumpsite had sunk in was noticeable for at least three days between October 1 and 3, but Rohit Prajapati of an environmental watchdog group Paryavaran Suraksha Samiti, noted that it was not the first time.

"This is the third time in four years that something so strange is happening. It is a disaster in the making and the authorities ought to examine the root cause of the problem," Prajapati says, adding that the department has repeatedly failed to properly address the issue.

He also contests the GPCB's claim that excess rain could lead to something so drastic. "Then why was similar impact not seen on other dumping sites in the region? One cannot arrive at conclusions for geological changes without a deeper study of them," he says. "It can have deadly implications."

Living in pollution

The villagers have also accused the GPCB of overlooking their complaint of water pollution which has rendered a large part of the land, most importantly, the gauchar or grazing land, useless.

"In the absence of a wall or a barrier, the pollutant has freely mixed with the water bodies here and has slowly started polluting both our soil and water," complains 23- year-old Nikul Kantharia.

He says ever since the mining project took off in the region, he, like most other villagers has been forced to take his livestock farther away to graze. "Nothing grows on the grazing land anymore and the grass closer to the dumpsite makes our cattle ill," Kantharia claims.

The mining work should have been stopped long ago

Prajapati and Bharat Jambucha, a well-known environmental activist and proponent of organic farming from the region, both point to blatant violations of environmental laws in the execution of mining work, with at least 12 violations cited by local officials. "But nothing happened after that. Mining work has continued without any hassles," Jambucha says. Among some glaring violations include the absence of a boundary wall around the dumping site and proper disposal of mining effluents.

The mining work has also continued without a most basic requirement – effluent treatment plant and sewage treatment plant at the mining site, Prajapati points out. "The mining work should have been stopped long ago. And the company should have been levied a heavy fine. But no such thing happened," he adds.

In some villages, the groundwater level has depleted over the past few years and villagers attribute it to the mining project. Women from Surkha village travel several kilometers outside for potable water. "This is new. Until five years ago, we had some water in the village and did not have to lug water every day," says Shilaben Kantharia.

The mine has affected the landscape around the villages

Sukanya Shantha/The Wire

Resisting lignite mining

The lignite mining project has a long history of resistance. Agricultural land, along with grazing land were acquired from the cluster of 12 adjoining villages in the coastal Ghogha taluka between 1994 and 1997. The locals estimate that villagers here lost anything between 40-100% of their land to the project. "We were paid a standard Rs 40,000 per bigha," Narendra, a local photographer, says.

The money, Narendra says, felt decent in 1994 but for those who had been dependent on this land, the years to come proved very challenging. "Several villagers have now taken a small patch of land in the neighboring villages on lease and are cultivating cotton and groundnut there," Narendra says.

They were dependent on others' land for work.

Bharat Jambucha says things get further complicated for the communities which were historically landless. "Most families belonging to the Dalit or other marginalized populations in the region never owned any land. They were dependent on others' land for work. Once villagers lost their land to the project, the landless were pushed out of the village," he adds. His organization, Prakrutik Kheti Juth, has been at the forefront, fighting for the rights of the villages affected in the lignite mining project.

In 2017, when the mining project finally took off, villagers from across 12 villages protested. The demonstration was disrupted after police used force and beat many protesters. More than 350 of them were booked for rioting.

The villagers, however, did not give up. Protests and hunger strikes have continued from time to time. A few villagers even sent a letter to the President of India threatening that they would commit suicide if the government did not return their land.

"We let them have our land for over 20 years," says Gohil.

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