13 Science Mysteries

This New Scientist article is a great overview of the following 13 mysteries, or "things that don't make sense" in science (although I don't think they should have included homeopathy):

• The placebo effect
• The horizon problem (of the Universe)
• Ultra-energetic cosmic rays
• Belfast homeopathy results
• Dark matter
• Viking's methane
• Tetraneutrons
• The Pioneer anomaly
• Dark energy
• The Kuiper cliff
• The Wow signal
• Not-so-constant constants
• Cold fusion