When in 1987 Francis Halzen, a phy - sicist based at the University of Wis - consin-Madison in the US, proposed lowering strings of light sensors down 1 km-deep holes in the Antarctic ice, many of his colleagues thought he was mad. His idea was to create a very un - usual kind of telescope, one that de - tects the light given off by neutrinos as they pass through, and interact with, the ice. Neutrinos are sought after be - cause, unlike electromagnetic radi - ation, they are not absorbed by gas or dust, which means that those reaching us from deep space can, in principle, let us “see” astronomical objects that would otherwise be hidden from view.
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