Go Back   Science Forums
View Single Post
Old 10-02-2008   #29 (permalink)
CraigD's Avatar
CraigD
Creating


Location:
Silver Spring, MD, USA
 
CraigD has a reputation beyond reputeCraigD has a reputation beyond reputeCraigD has a reputation beyond reputeCraigD has a reputation beyond reputeCraigD has a reputation beyond reputeCraigD has a reputation beyond reputeCraigD has a reputation beyond reputeCraigD has a reputation beyond reputeCraigD has a reputation beyond reputeCraigD has a reputation beyond reputeCraigD has a reputation beyond repute
 



Not Ranked  0 score     
Post The Aharonov-Bohm effect, "reaction", "interaction", and momentum

Quote:
Originally Posted by wade_b View Post
What about this (from physorg.com)
Quote:
One of the interesting phenomena present in quantum mechanics is the Aharonov-Bohm (AB) effect. The AB effect predicts that a charged particle, usually an electron in experiments, shows effects from electromagnetic fields in regions where the particle is excluded. This leads to the interesting fact that, in electromagnetism, Newton’s Third Law of Motion doesn’t always hold true.

Herman Batelaan explains …
Caprez, Barwick, and Batelaan’s 8/17/07 “A macroscopic test of the Aharonov-Bohm effect” describes an experiment that further confirms that the quantum waves of an electrons in a stream, which are predicted to be affected in the absence of an interaction analogous to classical electromagnetic force, are not actually being affected by an unexpected interaction analogous to a classical electromagnetic force.

What is changed by the AB effect is the phase of electrons’ waves, resulting in a detectable change in the interference pattern produced by passing a stream of electrons through two slits – the famous two-slit experiment. Their masses and velocities are unaffected. Newton’s 3rd Law of Motion describes forces, masses, and velocities, not the wave nature of particles, I think the tagline “in electromagnetism, Newton’s Third Law of Motion doesn’t always hold true”, while catchy, isn’t accurate. It plays on different uses of the word “reaction”: in classical physics, where reactions are changes in momenta, vs. in quantum physics, where “reaction” can be a rarely-used synonym for “interaction”, which can involve changes other than to momenta The word “reaction” appears nowhere in Caprez, Barwick, and Batelaan’s paper.

The AB effect expressly doesn’t change momenta, so I can see no way that it can be used for propulsion.


----------------
Moderator: Computers and Technology; Medical Science; Science Projects and Homework; Philosophy of Science; Physics and Mathematics; Environmental Studies
Reply With Quote
 
» Advertisement
» Current Poll
Who's the sexiest man alive? Johnny Depp or Robert Pattinson?
Johnny Depp - 30.00%
3 Votes
Robert Pattinson - 0%
0 Votes
Someone else (please specify) - 40.00%
4 Votes
I'm too macho to think a guy is sexy - 30.00%
3 Votes
Total Votes: 10
You may not vote on this poll.


All times are GMT -8. The time now is 12:58 AM.

Hypography?

Hypography [n.]: A combination of "hyperlink" and "bibliography" - ie, a list of links to electronic documents. Comparable to discography and bibliography, but not cartography.

We have been online since May 2000, and aim to be the best place to find and share science-related content of all kinds.

Share the love!

Please add more science to your life. Use our RSS feeds on your blog, your portal, or your favorite feedreader!


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2009, Jelsoft Enterprises Ltd.
Copyright © 2000-2009 Hypography
Part of the Hypography - Science for Everyone Network