Thee scientist who first proposed the idea to the European Space Agency (ESA), without success, in 2001, is University of Vienna physicist Anton Zeilinger.

"This field wouldn't even exist if people hadn't worried about the foundations of quantum physics," says Anton Zeilinger of the University of Vienna in Austria.

This week, an answer comes in a paper from Anton Zeilinger, a quantum physicist at the University of Vienna, and colleagues, published in the New Journal of Physics.