They can be tested, at least partially, by ultra-high energy cosmic ray experiments like the Pierre Auger Observatory.
It was Alan Watson who in the later years lead the research team and subsequently co-initiated Auger Observatory Collaboration.
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Meanwhile, from the Volcano Ranch (New Mexico, 1959–1978), the Fly's Eye (Dugway, Utah) and its successor the High Resolution Fly's Eye Cosmic Ray Detector called "HiRes" or "Fly's Eye" (University of Utah), the technique of the Fluorescence Detector was developed.
Pierre Boulez | Pierre Trudeau | Pierre-Auguste Renoir | Royal Observatory, Greenwich | Pierre Corneille | Jean-Pierre Rampal | Pierre Loti | Pierre | Pierre Teilhard de Chardin | observatory | Jean-Pierre Thiollet | Royal Observatory | Pierre Puvis de Chavannes | Pierre Cardin | Pierre Bourdieu | Pierre Amoyal | Paris Observatory | Pierre Huyghe | Pierre Bonnard | Palomar Observatory | Pierre-Constant Budin | Yerkes Observatory | Pierre-Joseph Proudhon | Pierre Beaumarchais | Arecibo Observatory | Siding Spring Observatory | Pierre Restany | Pierre Curie | Mount Wilson Observatory | Smithsonian Astrophysical Observatory |