A message from the dark side

摘要

Both astrophysicists and particle physicists are in on the hunt for the elusive dark matter that is thought to pervade the Universe. A high-altitude balloon-borne experiment offers the latest hints as to what it could be. Humiliating as it may sound, you, me and everything we see - the Earth, Moon, Sun and stars - may be little more than cosmic contamination. Most of the 'stuff' in the Universe is thought to be in the form of invisible and elusive particles of dark matter. To date, the existence of this cosmic exotica has been inferred through its gravitational effects. But on page 362 of this issue, Chang and collaborators report on a surprising bump detected in the spectrum of celestial electrons that could be a more direct signal of this mysterious substance - or there may be other intriguing explanations.