Space is not empty they say, is it a new idea or has it always been like that?
Can you explain what is the (current) real meaning of vacuum, which is just the Latin for empty
Can you also explain why space is not (or can not be) considered a medium in which light propagates, at a speed that depends only on the properties of the medium?
Could you also describe what would happen if space could be or would be found out to be a medium, whould the question of invariance of light and the equivalence principle be safe? What problems concerning light would remain unsolved? would space-time still be necessary to explain some issues?
Probably it is necessary to specify that I am not suggesting an additional medium (a new form of ether ), I am asking why space itself (the vacuum and not space-time) cannot be considered the medium (made up by virtual particle, quanta or other...) that has the necessary properties that can propagate EMR. If it does not qualify, what properties are missing?
- comments seem to suggest that space can and is considered a medium, but that it cannot be considered the medium in which light might propagate. Can someone explain why that it is so?