The definitive answer about the direction water swirls in two hemispheres Sync the videos yourself: toiletswirl.com For the record Destin and I repeated the experiment 3-4 times each in each hemisphere and got the same results every time. The idea that water going down a drain or flushed down a toilet swirls in opposite directions in the Northern and Southern Hemispheres has a long history. But few have ever done the experiment. Destin from Smarter Every Day and I performed identical experiments in the Northern and Southern hemispheres. What we found is the direction of water swirl in a toilet, sink, or bathtub is determined by other sources of angular momentum. However if the body of water is big enough, e.g. a kiddy pool, and left still for long enough (at least 24 hours), then the Coriolis effect is observable with water swirling counterclockwise in the Northern hemisphere and clockwise in the Southern hemisphere. Veritasium on Instagram: instagram.com/veritasium Patreon Support Link: www.patreon.com/veritasium Twitter: twitter.com/veritasium www.facebook.com/veritasium Smarter Every Day Instagram: instagram.com/smartereveryday Patreon Support Link: www.patreon.com/smartereveryday Twitter: twitter.com/smartereveryday www.facebook.com/SmarterEveryDay Gordon McGladdery did all of the sound design for the video. We used two songs from other artists (licensed of course). Derek split the first one up so it fades from video to video, and Gordon split the instruments up on the second one. There are violins on one video and percussion on the other for example. It's really neat. The neat earth animation at the beginning and the synchronizing timer was made by eisenfeuer.com/. He also made still images of the earth from the top and the bottom. Thanks to Vanessa for filming in Sydney: youtube.com/braincraftvideo MORE INFO: There was a study performed at MIT years ago (web.mit.edu/hml/ncfmf/09VOR.pdf) that explained the physics involved. We repeated some of these demonstrations, but on opposite sides of the globe…and in a way that can be easily understood. This site is a great resource on the Coriolis effect and ways people have gotten it wrong: www.ems.psu.edu/~fraser/Bad/Ba...

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