what is space?

Everything is made up of electromagnetic oscillations. Particles are just an illusion. I think that behind every particle there is a kind of electric or magnetic fields. If you want to go to the core of multidimensional, then the concept of electric and magnetic fields is of crucial importance. Even the gravitational field will one day be reduced to these two. I think that the Maxwell equations and ideas where the closest solution to these problems. Then come Einstein with a complication when he said that the speed of light is constant. A few who understand that speed is dependent on time (mathematically, every speed is derivation of space through time) and it should be treated mathematically like not constant, and this kind of scientist can understand more. Nikola Tesla was one of them.

Actually, when you come down to it, most of what we know of as reality is space. of course there is the space between celestial objects but even with that most of what we know of as 'solid' matter is really empty space. That's because matter is made up of elements that have a central nucleus and one or more electrons in the space surrounding them. Nuclei are small as are electrons. The electrons are constantly moving so, while they occupy the space around nuclei, they only occupy a very small portion of that space at any one time. Thus most of our reality is made up of empty space.