# Physics notation question

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#1
So this is embarrassing, a few years after graduating I've started to forget some bits and google isn't much help!

does someone here know what this means please?
𝜌̇= −𝑖[𝐻,𝜌]

what is this notation called and what does [𝐻,𝜌] represent please?

Thanks all!
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5 days ago
#2
The dot above a variable means a derivative with respect to time,
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#3
(Original post by Joseph Green)
The dot above a variable means a derivative with respect to time,
Thanks the dot part is easy. I forgot what the square bracket part means ([𝐻,𝜌]) :L
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5 days ago
#4
(Original post by swag dog)
Thanks the dot part is easy. I forgot what the square bracket part means ([𝐻,𝜌]) :L
Ah formating doesn't like square brackets I guess. I'm gonna make a guess and say that the square brackets mean commutators in Quantum mech terms. I haven't done it yet so I'm not sure but I saw it in a book and it looked similar
Last edited by Joseph Green; 5 days ago
1
#5
(Original post by Joseph Green)
Ah formating doesn't like square brackets I guess. I'm gonna make a guess and say that the square brackets mean commutators in Quantum mech terms. I haven't done it yet so I'm not sure but I saw it in a book and it looked similar
Thank you! just googled 'commutators in Quantum mech' and it came up.
[6,7] = 6*7 - 7*6
1
5 days ago
#6
(Original post by swag dog)
Thank you! just googled 'commutators in Quantum mech' and it came up.
[6,7] = 6*7 - 7*6
No problem. Good luck with your revision of this stuff,
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