[Phy撚圍爐區]數撚爆人PO又唔開(2)

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2021-07-06 21:28:43
2021-07-06 21:34:47
2021-07-14 13:22:53
2021-07-15 00:36:38
睇嚟大家都手殘
2021-07-15 03:54:50
2021-07-15 19:03:22
個爐有無人

想問下path integral formalism嘅問題

佢個idea大致係先將time evolution拆成n個/delta t嘅intervals,然後一堆數之後寫成path integral同functional integration。個phase就由個path 嘅action in出嚟

capital letters for operators.
我睇啲書個derivation,見都係話因為/delta t /to 0,所以雖然個e^iH /delta t 個H入面嘅term唔commute,例如P,Q,但係計first order 唔要second order就同commute一樣, CBH formula:
e^(i delta t (P^2+Q))=e^(idelta tP^2)e^(i delta t Q)e^(O(delta t ^2))

所以就可以拆開。之後再轉下base插下complete set咁。

個問題係,就咁睇每個e拆開之後個e^O(delta t ^2)係可以neglect,但係take delta t to 0即係n to inf,所以應個有無限多個e^()。每個error合埋晒會有e^O(delta t),所以應該唔可以neglect。唔止本書,好幾次見人都話delta t to 0,所以可以drop咗個higher order term當係commute咁做。但係加埋就唔係higher order呢

唔知我邊個位搞錯

其實仲有好多問題,不過太長,下次先
2021-07-15 20:58:47
2021-07-16 18:24:54
2021-07-17 08:11:16
2021-07-17 09:14:47
ODE single variable夠做
systems of ODE就識埋linear algebra

PDE就要multivariable calculus
2021-07-17 20:11:36
2021-07-17 20:43:37
2021-07-17 21:09:49
2021-07-18 01:30:08
thx
2021-07-18 02:44:17
一日最衰數撚

明明pi^2 = g = 10

否認嘅都係劣等民族
2021-07-24 01:34:46
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2021-07-26 12:38:13
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