Are we living in a simulation?
Unlikey to be honest, just think about the memory requirements to keep something that big running as a constant interacting with every entity. The best guess for the number of particles in the universe is
Multiply that by the bytes it takes to define a certain particle, let be generous and say 6! Assume you could engineer electrical components at the density of gold with pathways at one partical wide (unlikely) the memory chips alone would have to be well over the size of the current universe!
How would a computer project a 2D universe of that size. We are into realms of bulshit now. Now apply 3D and we are in total bullshit land.
Suppose we assume a Level of detail, starting at one person. That still requires a machine operating at silly numbers assuming a minimum of plunck time to calculate outcomes. To calculate the requirements of making a universe appear real for one person takes so much on every number level, it is silly to digest. Simple answer is no, we live in a real Universe. Be happy, you are a first😜
The smallest computer required to simulate a universe would be slightly bigger than the universe it was simulating!