Why Did Krylov Choose a Tippe Top for His Avatar?

[S.G. Janssens]

Hello all,

A.N. Krylov was a Russian naval engineer and applied mathematician. Although I'm not Russian myself, I decided to borrow his name for this forum, because I find him admirable. I'd like to extend my greetings to you all, hoping that I will now and then be able to contribute to answering questions while learning myself.

My training is in mathematics, with an emphasis on applications of functional analysis to numerical analysis and dynamical systems, particularly those involving delayed feedback. After losing interest in the natural sciences for a while, I have recently found examples from classical physics and engineering very beautiful and motivating, particularly those stemming from mechanics.

My best wishes,

Krylov.

P.S. My avatar is a picture of a "tippe top", one of my all-time favorite physical systems.

 

[andrewkirk]

Hello Krylov and welcome to physicforums!

My kids brought home some of those things in your picture the other day. I am intrigued by them. I tried to figure out how they work - why they turn upside-down when spinning - but I couldn't. Do you know how?

 

[Greg Bernhardt]

Welcome to PF!

 

[jtbell]

Welcome to PF! Some famous physicists have also been interested in the tippe top. For example, here are Wolfgang Pauli and Niels Bohr:

 

[S.G. Janssens]

Thank you all for your welcoming replies!

@andrewkirk: I'm sorry, but at the moment I cannot give you a satisfactory answer, other than that dissipation (dry friction) seems to play a crucial role: it gives rise to a torque on the stem of the top that in turn causes the top's inversion. This system only recently came to my attention again, and it was one of the factors that motivated me to start re-discovering (and this time, hopefully truly understanding!) what I learned a few years ago in the lectures on classical mechanics about rigid body motion. The wikipedia page about the tippe top has some old as well as recent references, but you probably found that out already.

By the time I will be able to do better, I might return to you privately. Maybe other more knowledgeable members can already tell more, but then I suggest to do this in a separate topic.

@jtbell: Thank you, I knew that photo and it's good it appears here. It is indeed very entertaining to see these two giants of quantum mechanics intrigued by a purely classical phenomenon!

 

[berkeman]

Welcome to the PF, Krylov!

And yes, this forum is just for new member introductions, so if folks want to discuss the physics of this tippe top, it would be best to start a new thread in the General Physics forum.

 

[jtbell]

Or if you're going to get into a serious mathematical analysis, the Classical Physics forum.