I recently came across this concept in a book on simulation theory and although my world hasn’t changed, the ways in which I now consider how my world exists have multiplied. Literally anything is possible in a limitless universe…
A Boltzmann brain is random particles forming, just for an instant, a brain that has all the memories of a real human, and all the things we think we see and smell and feel at that instant, and a sense that we are real.
That’s it. At any moment we could just be a Boltzmann brain that exists for that moment, and then disintegrates.
This is kinda the same that the real physical potential for a human to walk through a wall once every 100 million years, because all the particles do something odd at once.