In the weird world of quantum field theory, the property that entangles virtual particle pairs isn't spin or momentum—it's their 'occupation number' of modes. Think of it as two harmonic oscillators sharing a correlated fate across spacetime, as physicist Ted Jacobson explains in a recent podcast.
Unlike everyday entanglement between particles with definite spins, virtual particles pop in and out of existence, entangled by how many particles occupy a given field mode. This offers a deeper glimpse into the fabric of reality, where even fleeting quantum fluctuations can be intimately connected.
For the full discussion, check out the podcast 'The Physicist Who Proved Entropy = Gravity' with Ted Jacobson.