Hencrai equals free points

What property is a characteristic of a substance that can be observed and does not change the identity of the substance

What is the earliest point in the universe that we can observe? why can’t we see back further than this?

Two students, each riding bicycles, start from the same apartment building and ride to the same building on campus, but each takes a different route. the first student rides 1100 m due east and then turns due north and travels another 1430 m before arriving at the destination. the second student heads due north for 1930 m and then turns and heads directly toward the destination.at the turning point, how far is the second student from the destination?