Two physicists – Dr Maxim Pospelov from the University of Victoria and Prof Andrei Derevianko of the University of Nevada, Reno – have proposed a novel method for search of the mysterious and elusive material called dark matter.
Concept of a dark-matter search using atomic clocks; by monitoring time discrepancies between two spatially separated clocks one could search for the passage of topological defects, such as the domain wall pictured here. Image credit: A. Derevianko & M. Pospelov.
Dark matter is a mysterious substance thought to account for about 80 % of the mass in the Universe. It’s impossible to see, however, because it doesn’t emit or absorb light.
Physicists know it’s there because of its gravity, which influences the rotation of galaxies and bends the light emitted from distant objects in the Universe.
“Despite solid observational evidence for the existence of dark matter, its nature remains a mystery,” Prof Derevianko said.
“Some research programs in particle physics assume that dark matter is composed of heavy-particle-like matter. This assumption may not hold true, and significant interest exists for alternatives,”
“Our research pursues the idea that dark matter may be organized as a large gas-like collection of topological defects, or energy cracks,” Prof Derevianko said.
“We propose to detect the defects, the dark matter, as they sweep through us with a network of sensitive atomic clocks.”
The idea is, where the clocks go out of synchronization, we would know that dark matter, the topological defect, has passed by.
Prof Derevianko, who is the first author of the paper published in the journal Nature Physics, added: “in fact, we envision using the GPS constellation as the largest human-built dark-matter detector.”
The team is starting to test the dark matter detection ideas by analyzing clock data from the 30 GPS satellites, which use atomic clocks for everyday navigation.
“Correlated networks of atomic clocks such as the GPS and some ground networks already in existence, can be used as a powerful tool to search for the topological defect dark matter where initially synchronized clocks will become desynchronized.”
The time discrepancies between spatially separated clocks are expected to exhibit a distinct signature.
“We know the dark matter must be there, for example, because it is seen to bend light around galaxies, but we have no evidence as to what it might be made of,” said Dr Geoff Blewitt of the Nevada Geodetic Laboratory and the University of Nevada, Reno.
“If the dark matter were not there, the normal matter that we know about would not be sufficient to bend the light as much as it does. That’s just one of the ways scientists know there is a massive amount of dark matter somewhere out there in the galaxy.”
“One possibility is that the dark matter in this gas might not be made out of particles like normal matter, but of macroscopic imperfections in the fabric of space-time.”
“Our planet sweeps through this gas as it orbits the galaxy. So to us, the gas would appear to be like a galactic wind of dark matter blowing through the Earth system and its satellites,” he said.
“As the dark matter blows by, it would occasionally cause clocks of the GPS system to go out of sync with a tell-tale pattern over a period of about 3 minutes.”
“If the dark matter causes the clocks to go out of sync by more than a billionth of a second we should easily be able to detect such events.”
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A. Derevianko & M. Pospelov. Hunting for topological dark matter with atomic clocks. Nature Physics, published online November 17, 2014; doi: 10.1038/nphys3137
