Space is probably infinite, but we can see only the part that contains stars or galaxies whose light has been able to reach us, says Francis Halzen, a professor of physics.
The universe originated about 13.7 billion years ago with the Big Bang, so light cannot have been traveling for more than 13.7 billion years. “Since [...]

Use a cellphone? Love nature? Fear cancer? Then how can you hate science? Epidemics, environment, technology: We’ve got questions for the marathoners running (still?) for prexydent.

What was learned on Columbia’s last, tragic mission?