Wyndham Lewis accused Bergson of having "put the hyphen between space and time" (see durée)but it was Einstein and Minkowski who unified them.
The relativity of simultaneity is based on the fact that establishing simultaneity and measuring the speed of light form a "vicious, logical circle." Einstein needed to define the time of an event (a point-event in space-time) by reading a clock in the immediate vicinity (in space) of the event.
In 1907 Einstein theorized that light propagated across a gravitational field is curved. Since the trajectory of light is the shortest distance between two points and the basis for all measurement, he concluded that by slowing down the speed of light gravity warps time and space. He also hypothesized that gravity is not a force but an intrinsic curvature of a space-time continuum.
The following year, the German physicist Hermann Minkowski theorized that events should be conceived in a four-dimensional continuum represented by coordinates x,y,z, and t which are to be understood as units not entirely spatial or entirely temporal, not as distances or durations but space-time intervals.
Eight years later Einstein summarized the shift in world view. "It appears therefore more natural to think of physical reality as a four-dimensional existence, instead of, as hitherto, the evolution of three-dimensional existence."
Space-time, as opposed to what fills space-time "has no separate existence," as Einstein put it.
In 1924, Theo van Doesburg called for a plastic architecture based on non-Euclidean calculation and expressed in functional space-cells that project centrifugally rather than fitting into a closed cube. "Thus height, breadth, and depth plus time gain an entirely new plastic expression." ("Towards a Plastic Architecture" in Conrads, p. 79)
Alfred North Whitehead describes as the modal quality of space-time, the fact that "Everything which is in space receives a definite limitation of some sort, so that in a sense it has just that shape which it does have and no other, also in some sense it is just in this place and no other," just as in time a thing endures during a certain period, and through no other period."
(see simple location)