What type of material does sound travel fastest through?

Sound travels fastest through solids due to the tightly packed arrangement of molecules in these materials. In solids, the particles are in close proximity to one another, allowing vibrations caused by sound waves to transmit more efficiently from one particle to the next. As sound waves rely on the movement of particles to propagate, the density and elasticity of solids contribute significantly to the speed of sound. The compact structure enables quicker transfer of kinetic energy, making sound waves travel faster.

In contrast, gases have much lower density and their molecules are more spread out, which means that it takes longer for the sound waves to move through them as compared to solids. Liquids are intermediate; while the molecules are closer than in gases, they are still not as tightly packed as in solids, making sound travel slower through liquids than solids. Plasma, although less dense than solids, is formed of charged particles and conducts sound differently, but does not generally facilitate faster sound transmission than solids.

Thus, the efficiency in particle interaction and the medium's structural integrity make solids the fastest for sound propagation.