How radio waves can travel in vacuum. Sound waves can't do that, they need particle interaction.?

Question

So, why radio waves can do that? How can they travel in space?

Answer 1

Sound waves are a type of wave called matter waves. Like you said they depend on particle interaction.

Sound waves are a type of wave called a longitudinal wave, the air particles move back in forth in the same direction the sound wave moves in. They are just cyclical compression and rarefaction of the atmosphere.

The waves you see at the ocean are another example of waves. They are transverse waves, the water molecules move back and forth perpendicular to the direction the wave moves in.

Radio waves aren't matter waves, that is to say they aren't made up of matter. They are actually one out of many forms of electromagnetic radiation (x-rays, UV, and visible light are all other examples). Electromagnetic waves as their name might imply propagate through both electric and magnetic fields.

As a radio wave moves through space it creates variations in both the surrounding magnetic and electric fields. Like an ocean wave  radio waves are transverse waves, they create disturbances perpendicular to their direction of motion. In fact both the magnetic and electric fields are perpendicular to each other as well!

Electric and magnetic fields can exist anywhere, they don't need air or water for them to propagate through, just space.

You might be interested to know that any function that satisfies the partial differential function known as the wave equation is considered a wave:

d²f/dt² = v² (d²f/dx²)

Answer 2

Soundwaves require a medium, not for radiowaves. There's no molecule in vacuum since sound is the vibrations of molecules and caused by pressure waves. Radio waves are electromagnetic waves; they can travel through vacuum because  it's a field that has curvatures and metrics. Yep, particle interaction as radiowaves have quantum particles( packets of energy).  

Answer 3

Radio waves, like all electro-magnetic radiation are fundamentally different than pressure waves (sound), even though they share many similar properties. You are correct that sound (as a pressure wave, and pressure being something related to matter) requires a medium to travel through.

Radio waves on the other hand are an electric and magnetic phenomena. This type of wave does not require any physical medium, it can travel through a vacuum with no difficulty. The details of exactly how this really happens is a topic in advanced physics. However, if you have ever played with magnets you know first hand the reality of it.