if the particles are closer to each other, then the vibrations of particles will travel faster
vibration is motion. electromagnetic_radiation is both_wave_and_particle. escape_velocity is speed. expansion_of_universe is speeding_up. angular_velocity is speed. gravitational_waves is ripples_in_fabric_of_space_time. photons is both_particles_and_waves. scientists has discovered_particles_far_smaller_than_atoms particle_physics is physics. terminal_velocity is speed.