Quantum Fluctuations are the random, unpredictable changes in energy that occur at the quantum level. They're like cosmic burps that shake the very fabric of reality.
These fluctuations are caused by the Heisenberg Uncertainty Principle, which states that you can't know where something is or how fast it's moving unless you're observing it.
But don't worry, these fluctuations are just a natural part of the universe. In fact, they're what make life worth living, said every existential philosopher ever.