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HNQ
7:37 AM
1
Q: What kind of matter is Positronium?

Rajeev Ranjan SharmaWhat kind of matter is Positronium? normal matter, antimatter, exotic matter or something other? We know : Matter is made up of electron, proton and neutron. Antimatter is made up of positron, anti-proton and anti-neutron. But Positronium is made up of Electron and Positron. where electron is ...

 
HNQ
8:29 AM
4
Q: When an object crosses a black hole event horizon, does the entire object cross the event horizon "all at once?"

Maximal IdealThis is a follow-up question based on some discussions in one of my other questions posted here. Imagine a standard Schwarzschild black hole of sufficiently large size so that tidal forces are negligible at the event horizon. The question is, when a spatially extended object enters the black hole...

 
 
8 hours later…
HNQ
4:42 PM
3
Q: Why are phonons bosons if they cannot occupy the same eigenstate?

DamyHaoI am reading the The Oxford Solid State Basics and on pages 82-83 it appears the following: If a classical harmonic system (i.e., any quadratic Hamiltonian) has a normal oscillation mode at frequency ω the corresponding quantum system will have eigenstates with energy: $E_n=\hbar\omega\left(n+\f...

 
 
1 hour later…
HNQ
6:00 PM
3
Q: What is the connection between mechanics and electrodynamics that makes it necessary for both of these to obey the same principle of relativity?

user103515Mechanics obeyed Newtonian relativity (faithful to Galilean transformation) before Einstein. Einstein formulated Special relativity (faithful to Lorenz transformation) and Maxwell equations became invariant under Special relativity. So electrodynamics obeyed Special relativity. So far so good. Wh...

 
 
1 hour later…
HNQ
7:17 PM
7
Q: Is every finite circuit "solvable" using Ohm's law and Kirchhoff's loop rules?

KykyWhenever I have solved circuits (only cells, resistors and wires), it has only been necessary to use Ohm's law (or things derived from Ohm's law, such as how two resistors $R_1$ and $R_2$ have effective resistance $R_1+R_2$ as a whole) and Kirchoff's loop rules. However, I was curious as to wheth...

 
 
4 hours later…
HNQ
11:11 PM
1
Q: How can Planck's constant take different values?

RamanI have seen books and papers mentioning "In the semiclassical limit, $\hbar$ tends to zero", "the scaled Planck's constant goes as $1/N$ where $N$ is the Hilbert space dimension" etc. Could anyone explain these variable values taken by Planck's constant? What is the idea behind it? For all I know...

 

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