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UCPH scientist hopes LHC will find elusive dark matter

As the world’s largest particle smasher the Large Hadron Collider is ramped up with more energy than ever, a Copenhagen scientist offers his explanation of what it is all about

With hundreds of huge magnets and a 27-kilometre ring-shaped tunnel, the Large Hadron Collider (LHC) is like something out of a boyhood dream in itself. But Troels Christian Petersen, associate professor at the Niels Bohr Institute in Copenhagen, has a dream of his own: that the LHC will allow physicists to find out what makes up the Universe, including dark matter.

The LHC is a part of the accelerator complex CERN in Geneva, Switzerland, and is the largest and most powerful proton accelerator in the World. Troels Christian Petersen has for seven years, with 3,000 other international researchers, investigated the data from the LHC in order to understand which forces have shaped the Universe.

Troels Christian Petersen is from the Niels Bohr Institute at the University of Copenhagen

”As the Universe was created, there was loads of energy. Hereafter the Universe expanded and has become cold and dark and empty,” Troels Christian Petersen explains.

“Our mission is to give the empty space enough energy to unfold the physical laws as they did when the Universe was created, but now with us as the observers.”

Recreates a small, ‘Big Bang’

Two beams of protons are sent in opposite directions in the ring-shaped tunnel of the LHC where they collide. In 2012 the proton collisions proved the existence of the Higgs Boson, the particle that confers mass. The discovery was one of the most significant findings in physics history and earned its discoverers the Nobel physics prize in 2013.

After two years of upgrading and maintenance, the LHC has been turned on again. The upgrading means that the proton collisions happen at 13 teravolts in contrast to the earlier 8 teravolts.

“It is in these special moments, you get a new set of glasses allowing you to look deeper into the secrets of the Universe”.

The LHC has hereby once again made a historical step by setting a World Record for the highest particle energy level ever produced by scientists.

“The last time where science was able to significantly increase the maximum particle energy produced was in 2009 when the LHC was turned on,” says Troels Christian Petersen and adds:

“It is in these special moments, you get a new set of glasses allowing you to look deeper into the secrets of the Universe”.

Dream of dark matter

The discovery of the Higgs Boson was, according to Troels Christian Petersen, one of the more ‘expected’ discoveries. It is much more unpredictable which discoveries, if any, that will be done the next 10-15 years when the LHC is turned on.

“Dark matter is one of the primary candidates of what we hope to see,” says Troels Christian Petersen.

In the Universe there is 5 to 8 times as much dark matter as light matter. But in contrast to light matter, dark matter does not interact with electromagnetic forces. Dark matter can therefore not reflect, absorb or transmit light. This means that dark matter is extremely difficult to identify.

At the moment physicists all over the World are struggling to identify the elusive stuff. And this is also the case for researchers at CERN.

“If dark matter interacts with the weak nuclear forces, we will possibly be able to see this with the LHC”, says Troels Christian Petersen and adds:

“Experiencing this is my own secret dream!”

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