As a reference I will make the vague statement that others have posted the below on these forums: As one rolls back the clock, the size of the observable universe becomes smaller than it is today. Does this mean that all of what we observe today was more densely packed yesterday than it is today? If so, I understand that. Does this mean that we couldn't see as far away yesterday as we can today? If so, I don't understand that (and would be asking for help in understanding).