Here's why:

* Solids have molecules packed tightly together. This allows vibrations to transfer quickly and efficiently from one molecule to the next.

* Liquids have molecules that are more loosely packed, so vibrations take slightly longer to travel.

* Gases have molecules that are very far apart, making the transfer of vibrations very slow.

Think of it like this: imagine you're trying to pass a message along a line of people. If the people are standing close together, the message will travel quickly. If they are spread out, it will take much longer.