Christoph
Reputation
6,707
Next privilege 10,000 Rep.
Access moderator tools
 Jan 15 answered What is potential energy truly? Jan 15 comment Where is the potential energy saved? @Sofia: you'd have to ask Worldsheep about why he felt the need to qualify these statements; possibly, it has to do the GR (no energy density for gravity) and the non-uniqueness of the Poynting vector, but he may have been thinking about something completely different... Jan 15 comment Where is the potential energy saved? @Sofia: yes, we're in agreement; I just did not get your objection until your final comment Jan 15 comment Where is the potential energy saved? @Sofia: from your answer one understands that the electric field and the potential are due only to the bigger charge no, one has to consider the field generated by both charges; the potential energy comes from the mixed term when evaluating $|E_1+E_2|^2$ Jan 15 comment What is potential energy truly? yes, I was getting at the $00$ component of stress-energy; also note that Noether's 2nd theorem does apply to GR... Jan 15 comment What is potential energy truly? note that we need to answer the 'where' question for anything besides gravitational energy if we want to apply general relativity... Jan 15 comment Where is the potential energy saved? @Sofia: and the energy density of the electromagnetic field will have increased by the required amount; take 2 charge configurations A and B, integrate the difference of electromagnetic field energy density and you'll arrive at the potential energy Jan 15 comment What is potential energy truly? One does not need to imagine energy as being stored somewhere. Yeah, it isn't as if the energy density appears anywhere important - like, say, the RHS of the Einstein equations? :p Jan 14 comment Where is the potential energy saved? @Sofia: I do not understand your objection; as long as you only bring an arbitrary but finite amount of charges, the potential energy will be finite; anyway, if I recall correctly, the interpretation of potential energy as field energy (once you substract the self-energy of the charge) can be found in chapter 1 of Jackson's EM book Jan 14 revised Where is the potential energy saved? spelling: Poynting was a person Jan 5 awarded Nice Answer Dec 23 comment Difference between theoretical physics and mathematical physics? @Schlomo: it's a joke; Mermin is a well-known theoretical physicist and most likely the person who coined the term "shut up and calculate" as an approach to interpreting QM Dec 23 comment Independence of thermodynamic variables sounds good to me (I forgot to mention that at least one variable has to be extensive); also note that you can define conjugate pairs with respect to state functions other than energy - eg the entropy representation Dec 23 comment Independence of thermodynamic variables No answers yet? The variables must not be conjugate, and you need to switch from internal energy to the thermodynamic potential associated with your choice of variables... Dec 22 answered Difference between theoretical physics and mathematical physics? Dec 22 awarded Informed Dec 22 revised Feynman-Stueckelberg interpretation deleted 1 character in body Dec 22 comment Feynman-Stueckelberg interpretation @FredericThomas: see edit Dec 22 revised Feynman-Stueckelberg interpretation clarified Dec 22 comment Does the difference between contextuality, nonlocality and retrocausality depend on where we draw the boundaries? @CuriousOne: What was missing from Luboš exposition? Without decoherence, the Copenhagen interpretation is more religion than physics. Also note some more steps along the way towards a fuller understanding of QM that happened after the 30s: We got the path integral in the 40s, Gleason's theorem in the 50s, Bell's theorem in the 60s, the Lindblad equation in the 70s, decoherence experiments in the 80s, Shor's algorithm in the 90s, ...