Are the past, present and future real aspects of reality or are they just features of our experience of time? Is there no more to time and space than the temporal and spatial relations which hold between events and objects? Or should they rather be taken as sort of containers in which things exist and events occur? In other words, are time and space just containers or are they autonomous physical objects?
The role of time and space beeing containers or relations have been discussed controversially in physics.
An excellent review of the different viewpoints, e.g., Leibniz, Newton, Mach, Einstein, is Chap. 3 "Relativity and the Absolute. Is Spacetime an Einsteinian Abstraction or a Physical Entity?" is Green, Brian: The Fabric of the Cosmos. 2004.
According to the Special Theory of Relativity one has to consider spacetime. Only the combined concept has an objective meaning, independent from the observer. According to the General Theory of Relativity spacetime is a physical entity because it is affected by mass distributions. Big masses like the sun or black holes warp spacetime in their neighbourhood. That's a step beyond Ernst Mach.
Summing up, Greene writes concerning acceleration
[...] but it is acceleration relative to something just as real tangible, and changeable: a field - the gravitational field. In this sense, spacetime - by being the incarnation of gravity - is so real in general relativity that the benchmark it provides is one that many relationists can comfortably accept.
Added in 2018: The detection of gravitational waves confirms the statement of the General Theory of Relativity that spacetime is a physical object, not just a container. Gravitational waves are oscillations of spacetime due to the acceleration of masses.
There are several views, even in physics.
Newton posited absolute time and space; here, space and time were containers within which events occured. Here, space and time, though appearing together, are not autonomous in any dramatic way.
This changed with Einsteins revolution in physics which fused space and time into spacetime and showed that it was an autonomous dynamical object - it could have curvature that changed from place to place, or from time to time; this implied that spacetime was not merely a container for matter but that it too had some ontological weight in perhaps the same way that matter does - but differently.
However, we have a sense that the present is what exists now, that the past is no longer here, and the future is yet to become; this view, which is the common view, is the block theory of time; it is hard to reconcile with Einsteins theory; but a speculative theory called causal sets which takes as it's posits the causal structure that Einsteins theory gives to events in spacetime and also supposes that this structure of events is discrete and tries to marry this to a block universe.
It's probable that in all the theories of space and time we can come up with, space and time must be given a certain physical and objective being, which does not mean that they have the same ontological status of matter; for example, at the very beginning of Western science Aristotle distinguished place from the void and held the latter could not exist.
"Is there no more to time and space than the temporal and spatial relations which hold between events and objects?"
Time and space can't be classed together in this way to answer this question, since their reality is different:
Space relates to 'spatial relations' between objects, but time relates to the movement of objects in space. Space (between things) exists in the here and now - just like the present - but the past and future exist only in our cognitive experiences.
This may be helpful:
The question of whether or not space and time are real can be understood in several ways. One such way is asking whether or not space and time are illusory. Another way is of asking whether space and time have an existence which is independent of the things and events which occupy them. Thus: if all things and all events were removed from space and time - would there be anything left?
Now, Newton answered in the positive to this question; thus for instance about the notion of time he wrote (1729, Scholium to definition VIII):
"absolute true mathematical time of itself and from its own nature flows equably without relation to anything external"
In Newton's view, hence, space and time can exist independently of objects and events.
Leibniz however objected to Newton's view. He claimed that space and time are relative things, not absolute; and according to his view whenever we talk about space and time we in fact talk about spatial and temporal relations between objects and events. (Leibniz view is call relationism).
The debate between Newton and Leibniz can be found in the correspondence between Leibniz and Samuel Clarck (who was Newton's follower).