If you're on a space ship travelling at 0.86c, your Lorentz factor is 2, and so time is moving half as fast for you. Yet if you measure the speed of light it

If you're on a space ship travelling at 0.86c, your Lorentz factor is 2, and so time is moving half as fast for you. Yet if you measure the speed of light it will be the same. Then if you look out the window you will see the universe is 1/2 the size it used to be in the direction you are travelling.