Jump to content

Blog post: swansont: Putting Some Spin On It

SFN Blogs
in SFN Blogs

Featured Replies

University of St Andrews scientists create 'fastest man-made spinning object'

 

The team then used the miniscule forces of laser light to hold the sphere with the radiation pressure of light - rather like levitating a beach ball with a jet of water.

 

They exploited the property of polarisation of the laser light that changed as the light passed through the levitating sphere, exerting a small twist or torque.

 

Light, of course, can have angular momentum, so if the ball was changing the light from linear to circular polarization (or vice versa), the angular momentum change would have to come from the ball, so it would spin.

 

If my calculator skills are not failing me, the ball had around 10^17 h-bar of angular momentum, which isn't a lot for a macroscopic object. 10^17 photons is less than a tenth of a Watt-second's worth of visible light, or 10 mW for less than 2 minutes.
Read and comment on the full post

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.

Configure browser push notifications
Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.