<p>STOCKHOLM, Sweden — A Japanese and two American astrophysicists won the Nobel Prize in physics Tuesday for using some of the most obscure particles and waves in nature to increase understanding of the universe.</p>
<p>Riccardo Giacconi, 71, of the Associated Universities Inc. in Washington, D.C., will get half of the $1 million prize for his role in ``pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources.''</p>
