Physics Help Forum Casimir force and negative pressure
 User Name Remember Me? Password

 Theoretical Physics Theoretical Physics Help Forum

 Jan 12th 2011, 01:05 PM #1 Junior Member   Join Date: Nov 2010 Posts: 6 Casimir force and negative pressure Vacuum with a constant energy density d_vac exerts a negative presure p_vac = - d_vac cē. Between the plates of a Casimir experiment the energy density is less than d_vac, say d_cas < d_vac. Thus, the pressure that is exerted by vacuum between the plates should be p_cas = - d_cas cē > d_vac cē = p_vac. This means that p_cas > p_vac, the pressure between is plates is greater than the pressure outside. The force between the plates should be repulsive. The Casimir force is however attractive. Where is the mistake in my argument?
 Jan 17th 2011, 02:54 PM #2 Junior Member   Join Date: Nov 2010 Posts: 6 I guess I found the answer by myself. The fact that p_vac = - d_cas cē, is related to the Lorentz invariance of vacuum. See http://www.astro.ucla.edu/~wright/Pvac_details.gif. However, inside the Casimir plates Lorentz invariance does not apply and therefore p_cas is unequal to - d_cas cē. Probably (I do not know however how to proceed to show it) p_cas < - d_cas cē, so that p_cas < p_vac and the force is therefore attractive.
Jan 12th 2012, 01:06 AM   #3
Junior Member

Join Date: Jan 2012
Posts: 1
check for the magnitude of the pressure difference between the two regions i'e insi.

 Originally Posted by tholan Vacuum with a constant energy density d_vac exerts a negative presure p_vac = - d_vac cē. Between the plates of a Casimir experiment the energy density is less than d_vac, say d_cas < d_vac. Thus, the pressure that is exerted by vacuum between the plates should be p_cas = - d_cas cē > d_vac cē = p_vac. This means that p_cas > p_vac, the pressure between is plates is greater than the pressure outside. The force between the plates should be repulsive. The Casimir force is however attractive. Where is the mistake in my argument?
check for the magnitude of the pressure difference between the two regions i'e inside and outside the plates.

 Tags casimir, force, negative, pressure

 Thread Tools Display Modes Linear Mode

 Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post jaiii Theoretical Physics 0 Apr 5th 2014 05:04 AM ArthurDent Quantum Physics 0 Mar 14th 2013 03:47 AM Jayan Energy and Work 4 Feb 8th 2013 08:55 AM amacqueen Quantum Physics 1 Feb 15th 2011 03:25 PM pryphnoq Kinematics and Dynamics 1 Feb 3rd 2011 01:37 PM