That space is where we exist in the present, the ever-fleeting now.
Think it through.
The past does not exist. It's gone, never to be repeated, and not available to revisit, unless one can travel faster than the speed of light, in which case, one would only see the past as fluttering images much like in the cinema.
The future has yet to happen, so it also does not exist. One could travel at the speed of light and stop time relative to oneself. But that has the simple effect of stasis, in other words, freezing you in place while the rest of the universe plods on. When you return, you find that you skipped over a bunch of years and landed in the future. That doesn't change the fact that the future is always something yet to happen, and therefore does not exist.
One more thing…as far as we can tell, there is no fundamental unit of time. You can simply divide it into tinier and tinier fragments and still have a fragment of time—sort of like matter. Despite discovering what we now think are the fundamental particles of matter, the jury is out…since there are always ways to smash even those bits into smaller bits.
So, here we are, caught between the past and future, both of which do not exist. And considering that there is likely no fundamental unit of time, that leaves us in a conundrum. We appear to exist (based on the old cogito ergo sum assumption), but where?