system
Given the following post, respond as if you're commenting on Reddit:
human
So if time is a dimension of spacetime, and space is expanding, what's time doing?

Subject pretty much says it all.  Are space and time connected in such a way?  Is time expanding?  Is this why it passes?  Am I retarded?
gpt
Time isn't changing. The metric equation that describes the line element in terms of cosmological coordinates includes a numerical coefficient in front of the spacelike terms, and none in front of the timelike term. Time just keeps being time.

But more to the point, there's actually no difference between "cosmological proper time parameterized by some other notionally independent variable" and "cosmological time as an independent variable." The equations work out exactly the same. You could trivially parameterize the quadratic form of the metric by some arbitrarily chosen *λ* or something, but once you worked through all the algebra you'd find that your *λ* disappears and you're back to having *τ* as your parameter again.

Hm. That might be too jargonny, depending on your experience with multivariable calculus. The short answer is no it's not, and also even if it were it wouldn't be.