Is Space a Physical thing?

Author

CuriosityQuest
June 22, 2025

Relationism vs Substantivalism

Relationism says that space isn’t a thing on its own — it’s just a way to describe how objects relate to one another. Substantivalism, on the other hand, takes space to be an actual, real thing — like a material object that isn’t made of matter. Substantivalists view space as consisting of infinitesimal, identical points, which act as immaterial “containers” for matter. When matter moves, it moves from one point to another.

One argument for relationism is the shift experiment: if you were to move everything in the universe one meter to the left, nothing would really change. All distances between objects would stay the same, suggesting that space is defined by relationships, not by a separate entity.

An argument for substantivalism is the case of acceleration. When a car speeds up, the driver feels pushed back, but a pedestrian outside does not. A relationist might say that both are accelerating relative to each other — but a substantivalist would argue that only the driver is accelerating through space, which explains why only the driver feels the force.

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