* Waves need a medium: Waves, by their nature, require a medium to travel through. A vacuum, by definition, is the complete absence of matter.
* Electromagnetic waves are an exception: Electromagnetic waves (like light) are a special case. They can travel through a vacuum because they are self-propagating disturbances in electric and magnetic fields, rather than requiring physical particles to carry the energy.
So, in vacuum, there is only one speed we can talk about:
* The speed of light (c): This is approximately 299,792,458 meters per second. All electromagnetic waves, including light, radio waves, X-rays, etc., travel at this speed in a vacuum.
Important Note: While the speed of light is constant in a vacuum, it can slow down when traveling through different materials (like water or glass).
