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Feb2313 08:38 AM
ZapperZ

1 
36,754 
Hi,
In Sidney Coleman's Lectures he talked about space translations such that
...

Aug2913 09:03 AM
arkajad

1 
507 
Hi everyone,
I'm currently working my way through Dirac's Quantum Mechanics, and I found this proof really...

Aug2913 04:55 AM
Oxfordstudent

5 
662 
Hello! I would like to find a book which covers the historical development of Quantum Mechanics from which I can learn...

Aug2813 04:28 PM
Jano L.

2 
695 
In &5.6 writes:
"An (A,A) field (A is spin) contains terms with only integer spins 2A,2A1,...,0, and corresponds to...

Aug2813 11:55 AM
Bill_K

8 
1,047 
Hi All,
Following on from the last dumb question I asked...
Suppose you calculate the treelevel approximation...

Aug2813 07:21 AM
muppet

2 
500 
Hi all,
It was recently pointed out to me that the finite electron mass puts a lower bound on the Mandelstam...

Aug2813 05:44 AM
muppet

4 
549 
if there are two entangled particles
one of them is flying 80% the speed of light , one of them is on earth for...

Aug2813 04:51 AM
lyncsta

1 
479 
Hi PF
Somebody gave me this link
could you help me to understand why (9) has to be inserted in (7) when the...

Aug2813 04:43 AM
naima

2 
575 
Can we have a local hidden variable theory explanation for Bells theorem?
The outcomes of the mesurement (measuring...

Aug2813 03:33 AM
haael

7 
889 
One of the most important results of functional analysis is that for every bounded linear functional f: H → ℂ on a...

Aug2713 09:41 PM
strangerep

9 
1,055 
I had trouble understanding this and had brought it up before but I thought I'd start a new thread on it, in case...

Aug2713 03:31 PM
audioloop

8 
1,135 
Hello!
I'm finally starting to get a grip around quantum field theory. The last hang up is the following:
I've been...

Aug2713 01:09 PM
The_Duck

2 
757 
Standard Pauli spin matrices are:
Sx:
$$\left(\begin{array}{cc}0&1/2\\1/2&0\end{array}\right)$$
Sz:...

Aug2713 11:45 AM
kith

6 
780 
I know what the Mossbauer effect is. I know the crystal as a whole accepts the recoil not just the atom emitting the...

Aug2713 07:01 AM
Bill_K

1 
573 
I have been going through my Physics text book to brush up on my Quantum Mechanics before starting my next QM course...

Aug2713 04:11 AM
Daniel1992

5 
605 
After searching this forum for what exactly spin is my inference is that it is a misnomer for an electrons "intrinsic...

Aug2613 06:20 PM
San K

28 
1,678 
Is the nonrelativistic Lagrangian:
\mathcal L=\frac{1}{2}m \dot{x}^2
invariant under boosts x'=x+vt?
It...

Aug2613 12:12 PM
Bill_K

5 
717 
Hello, I'm having trouble calculating this commutator, at the moment I've got:
\left=\left=i\left=i\int d^{3}x...

Aug2613 04:59 AM
guillefix

5 
795 
How do I write a full Schrodinger equation, preapproximation, for a mixture? Let's say 75% H2 and 25% He by number of...

Aug2613 04:17 AM
kith

37 
2,482 
Hi,
I am going to sound ridiculous, but I was watching an online lecture on QM and the professor mentioned spins can...

Aug2513 11:01 PM
strangerep

1 
550 
In lecture 2 of the Entnglement lecture series at theoreticalminimum.com, Susskind is explaining a classical...

Aug2513 08:40 PM
meBigGuy

5 
667 
Dear Everyone,
I have a problem to be solved now. how to calculate the symplectic group SP(3,R) noncompact induced...

Aug2513 07:16 PM
dongsh2

4 
507 
Dear Sir,
I am currently doing an advanced course in Quantum Mechanics. This current doubt of mine, I am unable to...

Aug2513 06:58 PM
WannabeNewton

5 
984 
On page 403, diagram 12.1 (b) of Peskin and Schroeder, does anyone know why the coupling constant at first increases...

Aug2513 06:44 PM
Vic Sandler

1 
408 
Can someone explain how Dirac was able to deduce that antimatter exists? How did this follow naturally from Dirac's...

Aug2513 02:04 PM
tom.stoer

3 
619 
In the second edition of Mandl and Shaw QFT, on page 361, it's fairly obvious that there is a sign discrepancy between...

Aug2513 12:43 PM
Vic Sandler

24 
1,700 
Could anyone please push to the right direction...
Bohr's model of Atom. Energy quantized. Angular momentum.  I...

Aug2513 12:33 PM
epsaliba

1 
448 
Does the seemingly random nature of QM mean that the Universe is very non deterministic and does this mean that our...

Aug2513 11:42 AM
Tanelorn

65 
3,309 
How are the Hamiltonian and Lagrangian different as far as preserving symmetries of a theory? Peskin and Schroeder...

Aug2513 11:16 AM
jfy4

1 
371 
Some time ago I asked about contact forces and was directed to read about the Pauli exclusion principle and the...

Aug2513 07:35 AM
eightsquare

6 
718 
It is known that a charged particle moving with some acceleration emits electromagnetic waves. For example, this may...

Aug2413 10:28 PM
Ruslan_Sharipov

3 
845 
Hello all!
I'm trying to wrap my head around this quantum entanglement thingy. As far as I have understood, if you...

Aug2413 01:50 PM
Bill_K

1 
532 
The de broglie bohm theory posits that the photon goes through one of the slits and the waves through both. (In a...

Aug2413 01:49 PM
San K

14 
1,309 
If mass is quantised and energy is mass why isn't energy quantised. It seems that it's possible to have arbitrarily...

Aug2413 02:17 AM
physorguser

4 
906 
Sorry for reopening a closed thread. But I have exactly the same doubt as this guy:...

Aug2313 03:39 PM
guillefix

2 
599 
I'm interested in interpretations and comments regarding this Wikipedia snippet:
...

Aug2313 03:14 PM
DrClaude

6 
693 
In the second edition of Mandl & Shaw, QFT, on page 334, eqn (15.28) says:
G^{\alpha\beta}_r(k^2) =...

Aug2313 11:54 AM
Vic Sandler

0 
328 
As I understand it, EPR proposed their entanglement thought experiment as a means of demonstrating that Quantum...

Aug2313 11:39 AM
RUTA

165 
11,966 
the two energy level atom, whose hamiltonian takes the form
\hat{H_A}=E_gg\rangle\langle g+E_ee\rangle\langle e,...

Aug2213 06:25 PM
bobydbcn

2 
533 
Is there any thing that could, or any way to increase the atomic decay rate of already unstable elements, such as the...

Aug2213 10:32 AM
jfizzix

2 
478 