Acellerating expansion? Bah!

twofish-quant

I'm not so sure. Getting global energy to conserve in a hydro-simulation is much, much harder than it seems. There is a strong likelihood that the first time you run the code, it *won't* conserve energy and you'll be spending a month trying to figure out why.

Even trying to check if you've conserved energy in a 3-d Euler simulation is extremely non-trivial. You have matter falling into the simulation. You have radiation leaving the simulation, you have non-trivial matter-radiation interactions.

One problem with hydro simulations is that even very, very slight differences in energy balance will cause reasonable but incorrect results. It's not the huge bugs that you worry about, since huge bugs are obvious. It's the subtle complicated ones that keep you up at nights. There is also the fact that all numerical codes will have bugs. This is why "run the simulation and declare victory" won't work.

In any case, I won't feel confident in breaking out the champagne until you have three or four groups with different simulations and code bases, come up with the same basic mechanism for an explosion.