Difficult relativity question

[Anonymouser]

Think of the question in a relativistic manner: Keep thinking relativity!

An electric current flows in a wire (see figure). A proton moving parallel to the wire will experience a magnetic force due to the magnetic field created by the current. From the point of view of an observer travelling along with the proton, the proton is at rest and should experience no force. What do you say?
[center][attachment=3065:jonathan.PNG][/center]

Asked 2 physics teachers and their answers were physically correct, but I just don't think they're the answer for this question. Some help would be appreciated.

PS: This question is from the "Physics for the IB Diploma" book Fifth Edition. (Page 651 #9)
And no, the answer isn't at the back of the book =P

In case you couldn't see the picture above:
[url="http://img23.imageshack.us/img23/2358/jonathan.png"]http://img23.imageshack.us/img23/2358/jonathan.png[/url]

Edited March 18, 2009 by Anonymouser

[GNRS]

According to the special principle of relativity, physics laws are the same for inertial reference frames. If there is a force, there is an acceleration, so the proton and the wire won't be inertial frames. Therefore, there will be some relativistic effects in the proton (and theoretically there will be another effects in the wire as well), independently from the frame that you have chosen. So you can't say that there is no force because there are effects, and according to the causality principle, there can't be effect without cause.

In my opinion, with my limited knowledge about these issues, I would say that you can experience no movement if you are in the proton frame, but you have to consider a real force because of what I've said before.

Edited March 19, 2009 by GNRS