How do orchestras play together without getting lost?

Imagine fifty musicians crammed onto one stage — violins, trumpets, drums, flutes — all holding different sheets of paper covered in dots and lines. Someone counts to three, and suddenly they're playing the same song at exactly the same speed, hitting the same beats, swelling loud and soft together like one giant instrument. How do they not turn into a beautiful disaster?
The secret starts with one person: the conductor, standing front and center with a little stick called a baton. The conductor doesn't make a single sound, but everyone's watching. That baton becomes a magic wand that shows time itself — each wave marks a beat, like a visible heartbeat everyone can see.
