Two and a half years of evolution in site policy. The open question was asked in November 2010, early in our beta period, when the site was undergoing its initial burst of activity and its scope was still very much in flux. So it got a bunch of upvotes and then got forgotten. Since we don't go b...

How do you effectively study physics? How does one read a physics book instead or just staring at it for hours? (Apologies in advance if the question is ill-posed or too subjective in its current form to meet the requirements of the FAQ; I'd certainly appreciate any suggestions for its modifica...

A dipole has equal and opposite charges. The field lines originate from positive charge and terminate with the negative charge. When we derive for the torque acting on a dipole placed at an angle $\theta$ with the field, we obtain $\tau=\vec{p}\times\vec{E}$. And for the potential energy, we obta...

In 1967, Andrei Sakharov proposed the idea of Emergent Gravity, that perhaps gravity was emergent, i.e., not a result of a force. He did so because “many condensed matter systems give rise to emergent phenomena which are identical to general relativity”. On January 6, 2010, Erik Verlinde propos...