Cfrgtkky

I read a short story I believe vaguely around 2003 in a print magazine. A group of astronomers sends a laser to bounce off a planet circling Alpha Centauri or some similarly close star. But it turns out the universe is a simulation, the planet is outside the bounds of the simulation, and the laser breaks the program and the universe collapses around us.

If it helps, I believe it may have been in the same issue of whatever print magazine that was which also had a novella about aliens who come to Earth and turn out to be essentially movie directors who try to manipulate us into a nuclear war so they can get good special effects (sounds silly the way I describe it, but was not comedic).

This is "Touching Centauri" by Stephen Baxter. Collected in Phase Space, published in 2003. You can read the full text here.

From Wikipedia:

Scientists attempting to use a laser to contact another world inadvertently cause the end of their universe, while everyone struggles with the ultimate nature of their existence. (While snippets of the story are touched upon between each previous story, the full explanation is given here.)

Also published in Asimov's.