I recall that back in the day my thought was that "Or our model of gravity is just wrong and what we're observing is correct (as in, visible matter is causing t

I recall that back in the day my thought was that "Or our model of gravity is just wrong and what we're observing is correct (as in, visible matter is causing this behavior), we just don't understand how gravity works at massive scales because there are variables we aren't taking into account" but honestly it's been so long I forget all the basic info on this.