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.

Physics

Energy Conservation Principles

Quick fact

The principle of energy conservation is a direct consequence of time symmetry in physics, as proven by Emmy Noether's theorem in 1915.

Why this is interesting

You've heard 'energy is never created or destroyed,' but if that's true, why does a bouncing ball eventually come to a stop?