MinutePhysics (chronological order) - The "Mountain Or Valley?" Illusion

Thanks to Skillshare for supporting this video: http://skl.sh/MinutePhysics for 2 free months! This video is about a multistable perceptual illusion, similar to the hollow face illusion, whereby maps or aerial or satellite photos look upside down/inside out, ie, concave (valley) parts look convex and convex (mountainous) parts look concave. Just flip the images around and things will make a lot more sense! It's just because our eyes gauge depth based on the location of shadows, and the sun always casts shadows on the bottoms of things. Support MinutePhysics on Patreon! http://www.patreon.com/minutephysics Link to Patreon Supporters: http://www.minutephysics.com/supporters/ MinutePhysics is on twitter - @minutephysics And facebook - http://facebook.com/minutephysics And Google+ (does anyone use this any more?) - http://bit.ly/qzEwc6 REFERENCES Twitter posts: https://twitter.com/Astro2fish/status/859799730565414912 https://twitter.com/BadAstronomer/status/859800278358528001 Bad Astronomy Blog post: http://blogs.discovermagazine.com/badastronomy/2010/05/19/a-lunar-illusion-youll-flip-over/ Multistable perception http://en.m.wikipedia.org/wiki/Multistable_perception Top-left Lighting http://en.m.wikipedia.org/wiki/Top-left_lighting Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute! Created by Henry Reich