# Looking for a blog post

**URL:** <https://discourse.julialang.org/t/looking-for-a-blog-post/30822>\
**Category:** Community\
**Tags:** question, flux, blog-post\
**Created:** [November 7, 2019, 9:56am UTC](https://discourse.julialang.org/t/looking-for-a-blog-post/30822 "2019-11-07T09:56:32Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![bocc](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bocc/32/7546_2.png) [@bocc](https://discourse.julialang.org/u/bocc)\
**Post date:** [November 7, 2019, 9:56am UTC](https://discourse.julialang.org/t/looking-for-a-blog-post/30822/1 "2019-11-07T09:56:32Z")

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Hello All,

I remember reading a blog post about solving a system of charged particles with differentiable programming (Flux with Zygote perhaps) using a gradient based optimization method instead of explicitly solving the dynamics of the system - and I cannot find it anymore. There was an animation with dot sizes corresponding to charges, it was really nice.  
If this rings a bell, please tell me!

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**Author:** ![xiaodai](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xiaodai/32/15937_2.png) [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Post date:** [November 7, 2019, 1:22pm UTC](https://discourse.julialang.org/t/looking-for-a-blog-post/30822/2 "2019-11-07T13:22:15Z")

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[https://fluxml.ai/2019/03/05/dp-vs-rl.html](https://fluxml.ai/2019/03/05/dp-vs-rl.html)

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**Author:** ![bocc](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bocc/32/7546_2.png) [@bocc](https://discourse.julialang.org/u/bocc)\
**Post date:** [November 8, 2019, 5:54am UTC](https://discourse.julialang.org/t/looking-for-a-blog-post/30822/3 "2019-11-08T05:54:49Z")

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Thank you, but that’s not it unfortunately.

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**Author:** ![mauro3](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mauro3/32/292_2.png) [@mauro3](https://discourse.julialang.org/u/mauro3)\
**Post date:** [November 8, 2019, 6:25am UTC](https://discourse.julialang.org/t/looking-for-a-blog-post/30822/4 "2019-11-08T06:25:34Z")

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This one [https://fluxml.ai/2019/09/11/simulating-the-motion-of-charges.html](https://fluxml.ai/2019/09/11/simulating-the-motion-of-charges.html)?

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**Author:** ![c42f](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/c42f/32/52842_2.png) [@c42f](https://discourse.julialang.org/u/c42f)\
**Post date:** [November 8, 2019, 7:34am UTC](https://discourse.julialang.org/t/looking-for-a-blog-post/30822/5 "2019-11-08T07:34:38Z")

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Hmm, this post does miss a really essential point about the physics; simulating the dynamics of an N-body system of charges is very much _not_ equivalent to minimizing the energy function. At least, not without some kind of dissipation in addition to the normal Coulomb force between charges. If you imagine the charges are immersed in a very viscous medium the analogy between gradient descent and dynamics would be more reasonable.

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**Author:** ![bocc](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bocc/32/7546_2.png) [@bocc](https://discourse.julialang.org/u/bocc)\
**Post date:** [November 8, 2019, 8:25am UTC](https://discourse.julialang.org/t/looking-for-a-blog-post/30822/6 "2019-11-08T08:25:27Z")

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Yes, this is it, thanks 🙂 I now feel stupid for not finding it at fluxml.ai