In the vacuum of space, sound waves cannot propagate because sound requires a material medium to transmit its energy. Therefore, there is no highest possible frequency of a sound wave in the vacuum of space because sound waves cannot exist in a vacuum.
Sound waves are mechanical waves that propagate through the vibration of particles in a medium, such as air, water, or solid materials. In the absence of a material medium, like in the vacuum of space, there are no particles for sound waves to interact with and transmit energy. As a result, sound cannot travel through the vacuum.
However, it's important to note that electromagnetic waves, such as light, can propagate in the vacuum of space. Electromagnetic waves do not require a material medium and can travel through the vacuum as a result of the oscillation of electric and magnetic fields. Unlike sound waves, electromagnetic waves can have a wide range of frequencies, spanning from radio waves with low frequencies to gamma rays with very high frequencies.