so this saddle shape is basically what's called a quadruple gravitational potential so as you rotate this gravitational potential the ball is subject to alternating repulsive and attractive forces when it's rolling down the saddle it's repulsed from the center and when it's going uphill it's attracted to the center so if you can time it just right the periodic force towards the center and the repulsion away from the center get timed just right to nudge it and pull it and nudge it and pull it in the exact natural frequency of the ball so it stays right in the center this experiment took me a long time to get just right you have to get just the right frequency of rotation with the right saddle and the right ball to get it to work correctly but once you find it it's pretty easy to get the ball to stay in the gravitational trap and what's really cool about this is this experiment is comparable to something called a pall trap where you can trap ions so in a paul trap instead of having this gravitational quadrupole what you have is an electric quadrupole potential and you can actually trap charged ions in the center just like we trap in this gravitational well in a paul trap what you're doing is instead of spinning something you're alternating the electric fields so they go positive negative positive negative so it's attractive and repulsive at different times and if you match it just right you can actually get the ion to stay right in the center of the trap just like we were able to get the ball to stay right at the center of our gravitational trap so even though we have two completely different forces gravity and the electric force we can do basically the same experiment because when we have an uphill it's attracted to the center and a downhill it's repelled from the center it's the same as having an attractive electric force and a repelling electric force and thanks for watching another episode of the action lab i hope you liked it if you did don't forget to subscribe if you haven't yet and you can also hit the bell so you can be notified when i release my latest video and thanks for watching and i'll see you next time
START_INTERACTION_TOKEN and thanks for watching another episode of the action lab i hope you liked it if you did don't forget to subscribe if you haven't yet and you can also hit the bell so you can be notified when i release my latest video and thanks for watching and i'll see you next END_INTERACTION_TOKEN