We found one answer that claims:
“Good question. Scientists are still trying to figure this out. Look up just about any discussion on Dark Matter, which is the latest popular theory.
From a practical viewpoint, space is literally nothingness. Empty. Everything that exists in it came from the Big Bang (Stars, planets, interstellar gasses, nebula’s, etc.)”
Space is a relational concept. It refers to relationships between the positions of things. But it does not refer to some kind of “thing” out there in the universe which physics might someday find.
It most certainly is not nothingness! What sense would it make to refer to gravity as the curvature of space-time and then to talk about space being … nothing? How does nothingness bend and how does this explain gravity? Obviously, this is worse than useless.
Which brings us to this silly answer:
“The late, great Isaac Asimov dealt with this question in his SF novel “The Currents of Space” way back in 1952. A great read. His central character, a “spatio-analyst,” remarks that he analyzed “nothing”.”
Really? A rather absurd contradiction in terms, don’t you think? Granted, this is apparently from a fiction novel, but you sometimes hear some less-fictional people talk this way.
Here is another answer:
“In fact, space is a clear matter which doesn’t have any mass…we can say that space is a type of vacuum….Space is not made of something like air or else light like atmosphere…it appears black because no light scatters in space ….The fact is space is a place which is of nothing…But consists of things like planets, milky ways etc…”
No, it is not a kind of matter nor a type of vacuum. It is not made out of anything, as it is a relational concept. It is not a place, although this is somewhat closer to what it is than saying it is matter.
Space is a relationship between places. In the words of David Harriman, it is a “sum of places”. But “space” is not the same concept as “place”. It is a concept which identifies relationships between places.
And finally. we have this absurd answer:
“Space is a functional (imaginary) entity that is envisaged by rational beings, as a formless container, whenever they think of real entities. [It] extends to infinity means that however far you go, you can find real entities there and beyond.
Space becomes real only when it is filled entirely by real entities. A universal medium, structured by quanta of matter (in unobservable states), can fill the entire space and contain all other 3D matter-particles, which we consider as real entities. In this case, space and universal medium become synonymous. Space obtains reality. It can now deform, act and be acted upon.“
Functional entity? Imaginary entity? Ah, kind of like a giant metaphysical placeholder for matter? Like a giant metaphysical rubber sheet which is not a physical entity but is somehow affected by matter or physical entities?
This is quite similar to what many physicists seem to be describing when they talk about space-time. As though it is some giant metaphysical background upon which physical reality is somehow imposed.
So, apparently, it is not matter, not an entity. But not some abstraction either. As though it was some third category of existence. Something upon which existence is imposed. Possibly some precondition or background to existence? What the hell?
Whatever they are talking about, they are wrong. Space is an abstraction and has no physical existence. It is not something which warps or curves and therefore this is no explanation for what gravity is or how it works either. Regardless of what Einstein and others claim to have proven to the contrary.