Hello, When we assume the universe is expanding at a constant rate, we could say the age of the universe is 1/Ho. but I always feel unsure about that because 1/Ho is the distance over the velocity. However, the velocity changes over time, that is, when something is closer to us, the move slower and when they are further, they move faster according to Hubble's Law. So my question is how can we assume the velocity is constant the whole time it gets to the place it is now? Thank you in advance.