On Thursday, December 7, 2017 at 11:54:39 PM UTC, Bruce wrote: > > On 8/12/2017 10:40 am, [email protected] <javascript:> wrote: > > On Thursday, December 7, 2017 at 4:44:01 PM UTC, Bruno Marchal wrote: >> >> >> >> Yes, but only if the phase are indeed different at each slits, I would >> say. The interference pattern would shift. >> > > > > > > > > *I had a confusing and testy response from Bruce on this issue. To > recapitulate: AG> Are the phase angles of components of a superposition > identical? If so, is this the definition of coherence? TIA, AG BK> No, why > should they be equal. You really do have to learn some basic quantum > mechanics, Alan, and stop bothering the list with such questions. I might > be mistaken, but In the double slit I think the phase angles must be equal > to get the interference pattern observed, and if they're different at each > slit, we won't get what's observed. And if each component of a > superposition with many components has an arbitrary phase angle, I don't > see how we get coherent waves. I know this is not an interesting issue for > Bruce, but maybe he will clarify the situation. IIRC, on another message > list, Roahn, a Ph'D physicist known to Bruce, claimed the phase angles of > components of a superposition are equal. It would seem so, for if one has a > solution of the SWE and assigns a phase angle arbitrarily, and then expands > the solution in some basis, I think the basis vectors would inherit the > same phase angles. Still studying Bruce's link! * > > > Bruno is right on this -- the only effect of changing the phase in one arm > of the superposition would be to shift the interference pattern to the > side, it would still be the same pattern. >
*That's what I was trying to say above; shifting the pattern would be a new result IMO, same form but shifted in one direction. What I was puzzled about was the relation of the phase factors to coherence. If the superposition consists of three components with each pair of phases being multiples of each other, but not all three. Would the resultant superposition still be considered to be coherent? (not discussed in any links I can find). AG* > > This is explained in the Wikipedia page I referenced. Linearity of the SWE > means that the sum of any two solutions is also a solution, but the > individual solutions can be added with arbitrary complex weights (phases). > The overall phase has no physical consequences, but the relative phase is > all-important. There is no reason for the relative phases to be equal, they > can be anything at all. So in the two-slit experiment, putting a phase > changer in one arm simply shifts the pattern to the left or the right. This > experiment has been done. > > This is elementary quantum mechanics, and the details are readily > available on-line or in text books. > > Bruce > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
