2010-02-23 [Sunrose]: "Build" stuff :P

2010-02-23 [Hedda]: Hey, that is complicated engineering! The old Egyptians and Greeks didn't know how to build arches!

2010-02-23 [Hedda]: And that is actually a hyperbolic cosine, which is post-Newton kind of math.

2010-02-23 [Sunrose]: Oh I thought they did know how :O

2010-02-24 [Hedda]: They did? But they didn't build any.

2010-02-24 [Sunrose]: Didn't Eqyptians carve into rocks and make caves that way, with an arch at the entrance?

2010-02-24 [Hedda]: No, there are no arches even there:



But carving a round hole isn't the same as building an arch out of stone. An arch might seem like an obvious way to build a roof, but if you have never seen one it isn't obvious at all that it's a better way to do it.