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 [...]

A question from a very young reader, as relayed by his mother: “Where does the future come from, mommy? I don’t understand. How does it get here?”

Astronomers have just seen galaxies from the first billion years of the universe. They are also racing to understand dark energy, the force that’s spreading the universe apart.