Imagine you are standing on a platform, waiting for your train to arrive (the same train that George happens to be on). In the distance, you notice a beautiful mountain with the silhouette of an isosceles triangle (after all, you’re traveling in Switzerland, where Einstein developed special relativity). George also sees this exquisitely symmetrical Alp from his train window. Do you and George agree on the slope of the sides of the mountain (i.e., the angle of inclination relative to the horizontal axis)? Why?