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1  What 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 ... 8:29 AM
4  This 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… 4:42 PM
3  I 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: $E_n=\hbar\omega\left(n+\f... 1 hour later… 6:00 PM 3  Mechanics obeyed Newtonian relativity (faithful to Galilean transformation) before Einstein. Einstein formulated Special relativity (faithful to Lorenz transformation) and Maxwell equations became invariant under Special relativity. So electrodynamics obeyed Special relativity. So far so good. Wh... 1 hour later… 7:17 PM 7  Whenever I have solved circuits (only cells, resistors and wires), it has only been necessary to use Ohm's law (or things derived from Ohm's law, such as how two resistors$R_1$and$R_2$have effective resistance$R_1+R_2$as a whole) and Kirchoff's loop rules. However, I was curious as to wheth... 4 hours later… 11:11 PM 1  I have seen books and papers mentioning "In the semiclassical limit,$\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...