Saved on this device

Follow your curiosity

What discovery has been shared with you?

FACTREE gives you something interesting to discover every day — and something worth talking about together.

Start with one fact. Explore it, go deeper, then follow whichever branch catches your imagination.

Choose subjects for a surprise

Exploring any topic

Begin your discovery

Your next discovery is one click away.

Choose one or more subjects above, or leave Any Topic selected and let curiosity decide.

Astronomy

Cosmic Microwave Background: Evidence for the Big Bang

Quick fact

The cosmic microwave background was discovered accidentally in 1965 by Arno Penzias and Robert Wilson, who won the Nobel Prize—all because they couldn't get rid of a persistent hiss from their antenna.

Why this is interesting

When you tune an old analog TV to a channel with no signal, about 1% of the static you see is the oldest light in the universe—the cosmic microwave background. But how can a tiny hiss of radiation confirm a massive explosion billions of years ago?