If Spacetime Were a Superfluid, Would It Unify Physics—or Is the Theory All Wet?
If it is true that spacetime is a superfluid and that photons of different energies travel at different speeds or dissipate over time, that means relativity does not hold in all situations. One of the main tenets of relativity, the Lorentz invariance, states that the speed of light is unchanging, regardless of an observer’s frame of reference. “The possibility that spacetime as we know it emerges from something that violates relativity is a fairly radical one,” Jacobson says. It does, however, clear a potential pathway toward rectifying some of the problems that arise when trying to combine relativity and quantum mechanics. “Violating relativity would open up the possibility of eliminating infinite quantities that arise in present theory and which seem to some unlikely to be physically correct.”