# What does it mean to treat space and time on equal footing?

After some thought, this is what I understand:

In Newtonian physics, a particle's path can be specified by $x^i(t)$ where the time $t$ can be seen as an independent parameter. The space coordinates $x^i(t)$ are dependent variables that depend on $t$. We thus say that space and time are not treated on an equal footing.

In relativity, a particle's worldline is specified by $x^\mu(\lambda)$ where $\lambda$ is an independent parameter (often taken as the particle's proper time). Both space and time coordinates $x^\mu(t)$ are dependent variables that depend on $\lambda$. We thus say space and time are treated on an equal footing.

Putting space and time on the same footing means to treat time as another dimension in addition to the other three physical dimensions. In the context of relativity, time is treated as another dimension (but within this idea of Spacetime space and time are not the same).

In classical Newtonian physics, space is treated within the ideas of three dimensional space. In this approach, time is absolute, as oppose to relativity.