Timeline for answer to What happens to branching in the Many-Worlds Interpretation of quantum mechanics in the limit when Planck's constant goes to 0? by alanf
Current License: CC BY-SA 4.0
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| Mar 19, 2024 at 7:53 | comment | added | alanf | "This shows that classical mechanics cannot be regarded as emerging from quantum mechanics-at least in this sense-upon straightforward application of the limit $\hbar\to 0$."Quote from the abstract. I have explained the actual classical limit in my answer. | |
| Mar 19, 2024 at 4:38 | comment | added | Guillaume Laporte | @alanf: The paper you mentioned states various ways of taking limits in Schrodinger's equation which seem to have different outcomes; this indicates a problem with the approach I would guess.. In the question I asked, I assume there are localized particles initially (page 9); and that we can use propagators to evolve them, changing their Planck's constant along the way. You gave an answer to the first part, thank you : ) what about the end when $\hbar \to 0$ and then $\hbar = 0$ in all correlation functions? Going back in time, the limit exists and leads to the initial localized particles.. | |
| Mar 18, 2024 at 22:00 | comment | added | alanf | @GuillaumeLaporte $\hbar\to 0$ isn't the classical limit. It is neither necessary nor sufficient to produce classical behaviour as I explained above. For more discussion of the $\hbar\to 0$ limit see arxiv.org/abs/1201.0150 | |
| S Mar 18, 2024 at 18:31 | history | suggested | Stephane Bersier | CC BY-SA 4.0 |
Minor fixes, and "more or" -> "more-or-less"
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| Mar 18, 2024 at 18:10 | comment | added | Guillaume Laporte | I added a function (the bump function) to show that the constant can effectively start smoothly from zero, to non-zero value, and then back smoothly to zero. Everything should evolve nicely and continuously (even smoothly); from classical to quantum; and then from quantum to classical. But I still don't know what happens when the constant goes back to zero, what happens to the branches in the many-worlds at the end | |
| Mar 18, 2024 at 18:06 | review | Suggested edits | |||
| S Mar 18, 2024 at 18:31 | |||||
| Mar 18, 2024 at 18:00 | comment | added | More Anonymous | With dimensional constants the best one can do is take the ratio of the limit (which is dimensionless) to zero | |
| Mar 18, 2024 at 15:20 | comment | added | hyportnex | It is not the same if one assumes discontinuity in said limit; either way, continuity or discontinuity, is an assumption. | |
| Mar 18, 2024 at 10:52 | comment | added | alanf | "in the limit when Planck's constant goes to zero" is not the same as just setting it to zero | |
| Mar 18, 2024 at 10:23 | comment | added | hyportnex | but a zero is zero at all scales | |
| Mar 18, 2024 at 9:46 | history | answered | alanf | CC BY-SA 4.0 |