Isotropy and anisotropy: When a material is attacked by a liquid or vapor etchant, it is removed isotropically (uniformly in. all directions) or anisotropic etching (uniformity in vertical direction).
Some Questions Do Remain: 1  If the Earth was flat, we could travel to the place where the Earth and sky met. But we canât. 2  If the Earth was flat, we could reach the place where we could reach out and touch the Sun. But we canât. 3  If the Earth was flat, we could fall off the horizon. But we donâ 4 t. If the Earth was flat, it would simply fall.
For centuries, mankind knew all there was to know about the shape of the Earth. It was a flat planet, shaped roughly like a circle, with lots of pointy things hanging down from the underside. On the comparatively smooth topside, Europe sat in the middle of the circle, with the other continents scattered about the fringes, and parts of Africa hanging over the edge.