Part 6/7:
A key limitation of simulations is the sheer scale of the systems involved. Faithfully reproducing the Universe or even a galaxy would require computational resources on the scale of the entire Universe itself. Modelers have to make judicious choices about what to simplify and what to focus on.
There are also growing concerns about the energy use and carbon footprint of large-scale simulations, especially as the field of AI becomes more computationally intensive. However, cosmological simulations remain a tiny fraction of the global energy use of data centers and computing infrastructure.