Can Quantum Fluctuations Create a New Universe?

Quantum fluctuations happen everywhere, all the time, and in principle they can become arbitrarily large. So if we wait long enough at the end of the universe, brains can spontaneously assemble. Those are the so-called "Boltzmann Brains". And eventually, even an entire universe might be born. Seriously? Well, it depends on exactly how the laws of nature work.