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seen Dec 22 at 14:39

Oct
5
comment Why does Dirac write $\langle\xi'|\overline{f(\xi)} = \overline f(\xi ')\langle\xi'|$?
@KyleKanos Why doesn't Dirac just substitute $\xi'$ into $\overline{f(\xi)}$ as for (34)?
Oct
5
comment Why does Dirac write $\langle\xi'|\overline{f(\xi)} = \overline f(\xi ')\langle\xi'|$?
@KyleKanos Dirac uses $\xi$ for a real linear operator, ' to label objects connected with eigenvalues-- $\xi'$ for an eigenvalue, $\langle\xi'|$ for an eigenbra
Oct
5
asked Why does Dirac write $\langle\xi'|\overline{f(\xi)} = \overline f(\xi ')\langle\xi'|$?
Sep
24
accepted How does Dirac conclude that $X_r(c_r)$ cannot vanish?
Sep
24
accepted What experiments compete with BICEP 2, and when are their results expected?
Sep
24
asked How does Dirac conclude that $X_r(c_r)$ cannot vanish?
Sep
23
accepted How does Dirac form this conjugate imaginary equation?
Sep
23
comment How does Dirac form this conjugate imaginary equation?
@ACuriousMind This is page 30 of his book where the basic mathematical framework is based around there being a function of a ket, amongst other things. You really need to have a look at the book to see what I mean.
Sep
22
asked How does Dirac form this conjugate imaginary equation?
Sep
20
comment What axiomatizations exist for special relativity?
Nowadays, we'd say there is a universal speed limit c that light happens to travel at, making its measurement convenient.
Sep
18
comment How can (in Dirac's terminology) the product of two “real” linear operators be “not real”?
This answers my question. It would help if you could put $\alpha = \bar\alpha$ in brackets after Hermitian.
Sep
18
asked How is it shown that the composition of two real operators is generally not real?
Sep
3
accepted How does Dirac show that $\langle B|\bar{\bar{\alpha}}|P\rangle\;=\; \overline{\langle P|{\bar{\alpha}}|B\rangle}\;=\; \langle B|{\alpha}|P\rangle$?
Sep
3
comment How does Dirac show that $\langle B|\bar{\bar{\alpha}}|P\rangle\;=\; \overline{\langle P|{\bar{\alpha}}|B\rangle}\;=\; \langle B|{\alpha}|P\rangle$?
Indeed; I assumed that the adjoint of an adjoint cancelled like the inverse operator. It seems obvious now that the adjoint of an adjoint should initially be assumed to give a different linear operator since its still just a linear operator.
Sep
2
asked How does Dirac show that $\langle B|\bar{\bar{\alpha}}|P\rangle\;=\; \overline{\langle P|{\bar{\alpha}}|B\rangle}\;=\; \langle B|{\alpha}|P\rangle$?
Aug
26
accepted Can relativistic kinetic energy be derived from Newtonian kinetic energy?
Aug
25
comment Explanation for $E~$ not falling off at $1/r^2$ for infinite line and sheet charges?
@RonMaimon now that you've had a long rest, does this answer still make sense to you honestly?
Aug
24
comment Is there a “forwards” and “backwards” in one dimension?
So a magnitude can be negative?
Aug
24
accepted Is there a “forwards” and “backwards” in one dimension?
Aug
24
comment Is there a “forwards” and “backwards” in one dimension?
@HDE226868 sure you can. But maybe that isn't a true one dimensional space as defined by a physicist or mathematician, and a direction paramaterized by two discrete symbols +,- has been added.