It is not accurate to say that everything is made of light and sound. Light and sound are both forms of energy, but they propagate through different mediums and have distinct properties.
Sound waves are mechanical waves that require a medium, such as air, water, or solids, to travel. These waves are created by the vibration or oscillation of particles in the medium, which then transmit the energy from one particle to another. In the absence of a medium, such as in the vacuum of space, sound waves cannot propagate because there are no particles to carry and transmit the vibrations.
On the other hand, light is an electromagnetic wave that can propagate through a vacuum or free space without the need for a medium. This is because electromagnetic waves are composed of oscillating electric and magnetic fields that can self-propagate and do not require physical particles to travel through.
When scientists refer to "hearing" in the context of space, they are typically not referring to sound waves traveling through space. Instead, they use instruments and detectors to capture and analyze various forms of electromagnetic radiation, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. These different forms of electromagnetic radiation carry valuable information about celestial objects, such as stars, galaxies, and other astronomical phenomena. By studying these electromagnetic signals, scientists can gain insights into the composition, temperature, motion, and other properties of celestial objects, even though these signals are not sound waves.