Do space and time exist on their own, like adults?

Isaac Newton believed in the “intrinsic” reality of space and time. According to him, both space and time are certain substances, which means that they can exist even if there is nothing else besides them. Thus, space in Newton’s sense constitutes a kind of independent and absolute arena, existing by itself before things, but capable of assimilating them. in the course of it Absolute space, without relation to external objects, always remains the same and unchanged

[1]. »

Leibniz opposed this thesis, asserting that space has no real existence apart from the objects that make communication possible. In short, it would be secondary to material things: according to Leibniz, the world consists first of material things, without it being immediately possible to claim that they are in space. Space does not precede them and is no longer sufficient in itself. It appears only secondary to things to express their contiguous relations.

If there is absolute space, Leibniz wondered, why did God place it here instead of two feet? And if time is also absolute, why did God create the world at one time and not another? Since there is no reason to answer these questions, he must, according to him, abandon the hypotheses associated with these questions. Neither space nor time can be absolute.

What does contemporary physics say?

Not very clear. Like Newtonian mechanics, quantum physics is characterized by an intrinsic concept of space: space is described as a collection of points with predetermined and fixed properties. In these theories, the “container” of events, that is, depending on state, place, or space-time, is like a marble: it never reacts to what happens to its content.

But is the question like this settled forever? Can this concept be considered universal? The answer is no, because the way to describe this container of the universe is not the way general relativity holds, which describes gravity. This theory classifies gravity as the physical manifestation of the curvature of space-time. This is not immutable and immutable matter, which would be governed by the principles of Euclid’s geometry taught in school, but an elastic, jelly-like structure: it is capable of rippling, trembling and deforming with matter and energy. it contains. In other words, this theory presents a no longer intrinsic, but relational, structure of space-time: spatial relations are no longer fixed a priori within a given matter which would be space-time, because the geometry is neither predetermined nor a constant that depends on the amounts of matter and radiation present in the universe. Gravity distorts the structure of the universe no longer posited from the beginning, probably, as if the source of equations. In this context, we can no longer think of space-time, the things it contains and the events it hosts in an entirely separate way. (…)

[1] Isaac Newton, Mathematical Principles of Natural PhilosophyTranslated by the Marquis du Châtelet, Paris, Jacques Gabay, T. I, 1990, p. 8.

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