1) why can't sound travel through space but light can? 2) does space contain vacuum? 3) does space contain energy? 4) light is a type of energy right ? 5) so vacuum is a type of energy?
1 Answer
Okay let me answer your first question
Sound has special requirements. It works by rapidly changing the pressure of the medium it's in. This basically means it causes the molecules in the medium to alternately move closer together and farther apart. In a sound wave, what's actually travelling are these regions of high pressure (molecules close together) and low pressure (molecules farther apart). The actual molecules themselves don't travel very far, but the "disturbances" (the regions of changing pressure) can travel for miles.
So this means that sound depends on the presence of molecules. Without molecules, there's no such thing as "pressure," so there can be no changes in pressure, so no waves.
With light, it's different. Light propagates not by disturbing molecules, but by disturbing "fields" (electric fields and magnetic fields). It turns out that fields CAN exist in a vacuum, without any matter around them; so light can propagate through empty space.
