Could the universe be a simulation?

Yes — it’s possible in principle, but it’s still a speculative idea, not an established fact.

This is usually called the Simulation Hypothesis. A famous version, Nick Bostrom’s Simulation Argument, says one of these may be true:

1. Civilizations usually die out before they can run realistic simulations.
2. Advanced civilizations exist but choose not to run them.
3. We’re probably living in a simulation.

People point to things like the math-like structure of physics, quantization, and some ideas in quantum theory or string theory. But none of that proves a simulation.

The main skeptical points are:

• there’s no clear test for it,
• it may not be physically computable,
• and it can be hard to falsify.

Bottom line: it’s a philosophical possibility, not a scientific conclusion.