The incompatibility between Quantum Mechanics and Relativity is one of the stumbling blocks in physics Is it possible that this problem is related to the phenomenon of emergence? For example, a traffic engineer can treat the movement of a large number of vehicles as the flow of a liquid. But at the level of an individual car this does not work. Another example is the behaviour of a flock of starlings, at the individual level it is just a bird but in large numbers they form complex mathematical patterns in the sky So similarly, relativity may work when we are looking at very large numbers but break down at the micro level - just like the vehicle and bird analogy Nobody would say "how can this thing behave like a car at the micro level but like a liquid at the macro level?" so maybe at the micro level Quantum Mechanics holds sway but at the macro level Relativity holds sway?