# Tagged Questions

Energy is the conserved quantity associated to time-translation invariance and represents the work a system is capable of doing. Use this tag for questions about energy, and consider adding [tag:energy-conservation] if it is specifically about its conservation.

187 views

### Could energy be stored into (not extracted from) the quantum zero point field (like a battery)?

In order to explain the question clearly, I will make a short introduction. In 1962, Josephson predicted that for a sufficiently thin insulating layer, it should be possible for Cooper pairs to ...
57 views

### Energy of a particle as measured by an observer at infinity

I'm wondering if it is possible to make a definition for the energy of a particle as measured by an observer at infinity. I've looked through Wald for this but wasn't able to find anything - I may be ...
137 views

### Alternate Formulation of Kinetic Energy for Lagrangian

So I have a question regarding this system: It is supposed to be a simple model of an aircraft with the fuselage idealized as a concentrated mass $M_0$ and the wings modeled as rigid bars carrying ...
39 views

### How much energy is radiated when matter falls into a black hole

When a black hole consumes matter, it can form an accretion disc. Is there a relationship between the mass of the falling matter $m$, the mass of the black hole $M$, and the energy radiated during the ...
432 views

### How to convert Richter magnitude scale to approximate TNT?

I know the Richter magnitude scale is often used for measuring the strength of earthquakes. At the same time, explosive/destructive releases of energy are often quoted in equivalent amounts of TNT. Is ...
443 views

23 views

### Light bulbs Flashing on when disconnected

For the 2nd time I've had a lightbulb flash on in my hand after removing from the power socket. The first time the overhead light in my hallway was out for a couple of days before I got around to ...
28 views

### Reason behind the heat capacity of water

Water has a high specific capacity. Why can water release a large amount of energy without a great change in temperature?
20 views

### Energy density inside anisotropic materials

I'm taking some college courses on electromagnetism and there was some talk of energy stored by electromagnetic field and its density. The expression that we use to calculate energy density stored by ...
39 views

### Direct comparison of energy measurements for kids

I am planning a few physics & science sessions in the woods with 14 year-olds. The theme for one of the sessions is Energy, and my aim is to show them how gravity, solar radiation, wind (air ...
13 views

### Power Generation Via 2 connected objects below distinct orbits

As an example: Large weight A sits just below Earth's orbit Large weight B sits just below Moon's orbit A, B are connected by sufficiently strong material (may not exist, and if so how much ...
14 views

### What are the limitations of velocity selective coherent population trapping?

I'm somewhat familiar with limitations of Doppler cooling, particularly with the one photon recoil limit, but what I was curious about was what is the next barrier to cooling approaching absolute zero?...