Why distance is relative

Most people know that time is relative, but they do not know that distance is relative as well.

Seen from a very fast travelling spaceship, the distance between two stars can be shorter than seen from the Earth. This is called length contraction. It is not an optical illusion. The distance between the two stars is relative, just like time is relative. If you travel fast from the one star to the other, the distance will get smaller, so that you get there faster. That means faster according to your own clock. The clock on Earth will tick longer. People on Earth will not see the distance getting shorter.

By reading the book A New Understanding of the Universe, you will learn the logic of why distance gets shorter at high speed. You will be able to see it from a four-dimensional perspective and understand why length contraction occurs.