# \[ANN\] AstroNbodySim.jl: Unitful and differentiable gravitational N-body simulation code in Julia

**URL:** <https://discourse.julialang.org/t/ann-astronbodysim-jl-unitful-and-differentiable-gravitational-n-body-simulation-code-in-julia/74782>\
**Category:** Package Announcements\
**Tags:** package\
**Created:** [January 18, 2022, 6:10am UTC](https://discourse.julialang.org/t/ann-astronbodysim-jl-unitful-and-differentiable-gravitational-n-body-simulation-code-in-julia/74782 "2022-01-18T06:10:50Z")\
**Posts on this page:** 1\
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**Author:** ![lmiq](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lmiq/32/18314_2.png) [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Post date:** [January 18, 2022, 5:23pm UTC](https://discourse.julialang.org/t/ann-astronbodysim-jl-unitful-and-differentiable-gravitational-n-body-simulation-code-in-julia/74782/15 "2022-01-18T17:23:12Z")

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> [@islent](#):
>
> but if you have all uncertainty measurements in your initial conditions, you can get a reliable uncertainty prrdiction

See this comment and some associated discussion: [Notebook on particle simulations - #3 by ChrisRackauckas](https://discourse.julialang.org/t/notebook-on-particle-simulations/68496/3)

A curiosity: in a typical simulation with periodic boundary conditions, how big (system size) and how many particles (10^6?) are we talking about?

Can these calculations be performed with a cutoff (great enough such that the gravitational potential is small yet much smaller than the system size?). How many time-steps/second is a good benchmark? (I’m curious how would the trees compare with [cell lists](https://github.com/m3g/CellListMap.jl) with a sufficiently large cutoff if that is possible).

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