« first day (2377 days earlier)      last day (31 days later) » 

5:37 AM
Q: Different Hilbert spaces in quantum mechanics

DanIn a lot of literature the notion of different Hilbert spaces has been mentioned. In QFT, for non-interacting theories the Hilbert space is a called a 'Fock space', this is different from the interacting theory 'Physical Hilbert Space'. When the notion of Hilbert spaces was introduced to me it wa...

8 hours later…
1:28 PM
Q: What happens to the rotational kinetic energy?

IAmSoNBThere is a classic example that a spinning skater pulls his arms back. The angular momentum is conserved, the moment of inertia decreases. And therefore, it's angular velocity increases, so the rotational kinetic energy will increase. But what will happen if the skate pushes his arms outward? The...

9 hours later…
10:35 PM
Q: Why particles only make sense in flat spacetime?

wasnikI don't understand why exactly the notion of particles only makes sense in flat spacetime. From explanations I have read, it says that in general curved spacetime a unique vacuum couldn't be talked about as different coordinate systems used to describe the spacetime would imply different vacuum, ...


« first day (2377 days earlier)      last day (31 days later) »