Electromagnetic waves help. How do they travel?
Electromagnetic radiation (radiates or travels in a straight line) travels as photons or tiny packets of pure energy. The stronger the energy the shorter the wavelength of the photon and the more penetrating the photon. UV has shorter wavelengths than infrared and X-rays are even shorter and more penetrating but not as short and penetrating as gamma rays. The photons can travel through a pure vacuum because there is nothing there to absorb or reflect them. If the photons penetrate matter they may be absorbed, reflected or pass through (at a slower speed but unchanged). Photons can interact with the electrons orbiting atoms and molecules kicking them up into higher more energetic orbits. When energized electrons return to rest states in one or more steps, they emit one or more new photons of of the same or different wavelengths. Perfect mirrors reflect photons with nil change and perfect transparent glass allows photons to pass through unchanged. Photons can be studied as tiny particles
