Tadashi Tokieda is back. This time talking about stability, instability and train wheels.
More Tadashi videos: http://bit.ly/tadashi_vids

Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile

We are also supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science.

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Videos by Brady Haran
Editing and animation in the is video by Pete McPartlan

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A NOTE ON THIS VIDEO:
A few of our Tadashi videos blur the already blurry line between mathematics and physics... Some people suggest they may be a better fit on Brady's dedicated physics channel (called Sixty Symbols).
In response, the reasons they are on Numberphile are:
1) Tadashi, while certainly a modern polymath, is based in a mathematics department.
2) This sub series (with its animation and extra production work) has been supported by the Mathematical Sciences Research Institute, a Numberphile collaborator.
3) Some of the previous and future Tadashi videos are more mathoriented than physics and it just makes sense to put them on one channel rather than dividing the series between two channels on an ad hoc basis.
In a multidisciplinary world, it is challenging to run YouTube channels which people come to associate with just one discipline.
That said, feel free to go over and watch hundreds of physics videos on Sixty Symbols    / sixtysymbols