Physics Simulations

These all look like physics engines for graphics rendering. They all say 2d or 3d, and that means they surely can't handle concepts like relativistic spacetime.

Do you know of any libraries for doing 'backend' physical simulations, such as calculating scattering amplitudes, making projections of spacetime models onto either space-like or time-like slices, and, especially, using tensor networks for modelling condensed matter interactions?

Re: Physics Simulations

#5

Post by toisanji » Wed, Jan 03, 2018, 7:34 PM UTC

philipov wrote: post #4

tapirl wrote: post #2

cool! Included here: https://www.tapirgames.com/blog/open-source-physics-engines

These all look like physics engines for graphics rendering. They all say 2d or 3d, and that means they surely can't handle concepts like relativistic spacetime. Do you know of any libraries for doing 'backend' physical simulations, such as calculating scattering amplitudes, making projections of spacetime models onto either space-like or time-like slices, and, especially, using tensor networks for modelling condensed…

you should add pybullet as well.

Re: Physics Simulations

#6

Post by fwilliams » Wed, Jan 03, 2018, 7:45 PM UTC

philipov wrote: post #4

tapirl wrote: post #2

cool! Included here: https://www.tapirgames.com/blog/open-source-physics-engines

These all look like physics engines for graphics rendering. They all say 2d or 3d, and that means they surely can't handle concepts like relativistic spacetime. Do you know of any libraries for doing 'backend' physical simulations, such as calculating scattering amplitudes, making projections of spacetime models onto either space-like or time-like slices, and, especially, using tensor networks for modelling condensed…

Writing a general engine to do all these things is likely not a reasonable thing to do.

Complicated dynamical systems usually involve solving PDEs and for that you need to discretize your domain. How you choose to do so will drastically affect the numerical properties of your simulation. Most "real-physics" simulators tend to be specialized to a given task or even a given domain (for example simulating heat diffusion in an engine part). There's a whole literature on finite element methods to simulate various physical phenomena though it can be quite dense.

The generic game physics engines use very simple models of mechanics and allow for numerical issues (e.g. by using finite differences) in exchange for being real-time. If you're looking to simulate more advanced physical phenomena for a game, you're going to have to make similar trade-offs and will have to choose which ones make for the best gameplay.

Re: Physics Simulations

#7

Post by musgravepeter » Wed, Jan 03, 2018, 8:05 PM UTC

philipov wrote: post #4

tapirl wrote: post #2

cool! Included here: https://www.tapirgames.com/blog/open-source-physics-engines

These all look like physics engines for graphics rendering. They all say 2d or 3d, and that means they surely can't handle concepts like relativistic spacetime. Do you know of any libraries for doing 'backend' physical simulations, such as calculating scattering amplitudes, making projections of spacetime models onto either space-like or time-like slices, and, especially, using tensor networks for modelling condensed…

This might be of interest for spacetime modeling: https://arxiv.org/abs/1712.07658

Re: Physics Simulations

#8

Post by philipov » Wed, Jan 03, 2018, 8:06 PM UTC

fwilliams wrote: post #6

philipov wrote: post #4

Earlier quoted context omitted.

These all look like physics engines for graphics rendering. They all say 2d or 3d, and that means they surely can't handle concepts like relativistic spacetime. Do you know of any libraries for doing 'backend' physical simulations, such as calculating scattering amplitudes, making projections of spacetime models onto either space-like or time-like slices, and, especially, using tensor networks for modelling condensed…

Writing a general engine to do all these things is likely not a reasonable thing to do. Complicated dynamical systems usually involve solving PDEs and for that you need to discretize your domain. How you choose to do so will drastically affect the numerical properties of your simulation. Most "real-physics" simulators tend to be specialized to a given task or even a given domain (for example simulating heat diffusion…

Thank you, that all sounds right. I've been looking for, perhaps not a single engine, but rather specialized libraries I could glue together that handle different aspects of the problem. Sounds like I'll have to roll my own from scratch.

Can you recommend any general-purpose libraries (preferably with python bindings) for tensor calculus?

Re: Physics Simulations

#9

Post by musgravepeter » Wed, Jan 03, 2018, 8:16 PM UTC

philipov wrote: post #8

fwilliams wrote: post #6

Earlier quoted context omitted.

Writing a general engine to do all these things is likely not a reasonable thing to do. Complicated dynamical systems usually involve solving PDEs and for that you need to discretize your domain. How you choose to do so will drastically affect the numerical properties of your simulation. Most "real-physics" simulators tend to be specialized to a given task or even a given domain (for example simulating heat diffusion…

Thank you, that all sounds right. I've been looking for, perhaps not a single engine, but rather specialized libraries I could glue together that handle different aspects of the problem. Sounds like I'll have to roll my own from scratch. Can you recommend any general-purpose libraries (preferably with python bindings) for tensor calculus?

Take a look at SageManifolds: https://hyperspace.uni-frankfurt.de/2017/01/20/sagemanifolds...

My understanding is the numerical GR community is moving in this direction. The theory people tend to roll their own inside of Mathematica or Maple. Some Maple users use GRTensorIII (https://github.com/grtensor/grtensor)

Disclaimer: I am a co-creator of GRTensorIII

Re: Physics Simulations

#10

Post by philipov » Wed, Jan 03, 2018, 8:32 PM UTC

musgravepeter wrote: post #9

philipov wrote: post #8

Earlier quoted context omitted.

Thank you, that all sounds right. I've been looking for, perhaps not a single engine, but rather specialized libraries I could glue together that handle different aspects of the problem. Sounds like I'll have to roll my own from scratch. Can you recommend any general-purpose libraries (preferably with python bindings) for tensor calculus?

Take a look at SageManifolds: https://hyperspace.uni-frankfurt.de/2017/01/20/sagemanifolds... My understanding is the numerical GR community is moving in this direction. The theory people tend to roll their own inside of Mathematica or Maple. Some Maple users use GRTensorIII ( https://github.com/grtensor/grtensor ) Disclaimer: I am a co-creator of GRTensorIII

Thank you! This is exactly what I was looking for.