[tshaddox]

That’s not intuitive to me. Any old physics engine in a video game has infinite speed of causality and all the other classical physics stuff seems to work, including time. There must be some other unmentioned property of our Universe’s physics that is important and which requires finite speed of causality.

[kgc]

Simulators do have finite time steps. Without them they'd present the end of a simulation once initiated.

[Jyaif]

Interestingly, infinite speed of causality in games works, but does not scale.

If you want to simulate a giant world with millions of players, you either have to slow down the frequency at which you update the world to give the computer enough time to do the computation, or you have to introduce some sort of speed of causality in the game in order to be able to distribute the computation across multiple nodes.

[tshaddox]

How does a finite speed of causality help simulation performance? You still end up computing the interaction of every event with every particle in the Universe. Despite being amortized, you still need to compute the same number of interactions per unit time.

[Jyaif]

Finite speed of causality helps scale the compute across multiple servers.

If you have an infinite speed of causality, a server may need to receive data from all the servers. In the worst case, all servers will need to receive data from all the servers.

With finite speed of causality, a server only needs to receive data from the servers that simulate parts of the world that are nearby.