大家有無咩關於physics嘅問題但又無地方問

唔係無真正答案 而係未知
Objective collapse theory原則上係可以實驗驗証既

波長同波速都變 頻率無變

無架 Maxwell equation 都係話當factor左 vacuum 既permeability 同permittivity 之後開個方再1/x
實際既proof 你可以Google 下

imaginary number 你想像成X-Y axis 咁
X 係 real part Y 係imaginary part 咁
但係本身imaginary number pyhsically 係無意義既因為你本身就pass 唔到個boundary

時間停止咪就係當你relative to a reference frame (earth) reach 光速既時候, according to Lorentz transformation 你pass 既time 會 approach to 0
呢個都係點解time travel 向前係possible
但係travel back in time 要 speed > speed of light 而係physically impossible

即係波長短左，波速慢咗？

以中學黎講 係

學術上, 而家點解釋量子糾纏?

點會會有光速上限?

重力/ 引力點樣形成?

Maybe this
https://arxiv.org/pdf/1112.4187.pdf

唔係中學黎講係點？

https://youtu.be/CUjt36SD3h8
https://youtu.be/NLmpNM0sgYk

我覺得佢個組織可以再改善下 不過我懶

糾纏既state即係any state that is not a product state，即係當composite system既state唔可以用particle 1 in state A，particle 2 in state B黎描述既時候

量子糾纏有個聽落好勁既hypothesis叫做ER=EPR
ER指蟲洞，EPR指量子糾纏，個hypothesis係話其實量子糾纏就係由蟲洞連埋
但完全睇唔明d數學

the lagrangian will be invariant under the gauge transformation. for simplicity u can view global symmetry is like e^ialpha where alpha is constant and gauge symmetry is like e^i alpha but now alpha is a function of spacetime

Physics 學到咩位開始絕望

有冇人講下thermodynamics, what is temperature

lm

太陽系八大行星係因為太陽嘅引力而圍繞佢公轉？
咁點解太陽一人定唔會吸晒八大行星去太陽入面？

嚴格啲嚟講，gauge symmetry is not a symmetry.

Symmetry: Mapping between different physical states such that the equation of motion remains unchanged (usually).

Gauge symmetry: labelling the same physical state by different labels. （如果你熟differential geometry嘅話，可以理解成 principal bundle automorphism）

呢點其實幾重要，因為如果撈亂咗呢兩樣嘢嘅話，instantons，”large gauge transformation”，Elitzur’s theorem 之類嘅 concepts 會變得好難明。不過比較舊嘅field theory textbooks好似好少emphasise呢樣嘢。