Here's why:

* The Nature of Sound: Sound travels as vibrations that propagate through a medium. The molecules in the medium vibrate and transfer energy to their neighbors.

* Density and Stiffness: The speed of sound depends on the density and stiffness (elasticity) of the medium.

* Density: Denser materials have molecules packed closer together, allowing for faster energy transfer.

* Stiffness: Stiffer materials resist deformation more strongly, enabling vibrations to travel faster.

Solids have the highest density and stiffness compared to liquids and gases. This allows sound waves to travel through them at significantly higher speeds.

Here's a general order of sound speed:

* Solids: Fastest

* Liquids: Slower than solids

* Gases: Slowest

Let me know if you'd like more details about why this is the case!