The space between two closely spaced surfaces is far from empty: it's a seething "quantum glue." Within it, quantum fluctuations continuously pop in and out of existence: microscopic bursts of energy in electromagnetic fields that, according to quantum theory, give the vacuum a dynamic structure. These fluctuations create an attractive or repulsive force — the Casimir effect, named after Dutch physicist Hendrik Casimir, who predicted it in 1948. Today, researchers are learning to harness this effect to levitate objects without mechanical support.

In the experiment, researchers placed a polystyrene plate above a Teflon substrate and filled the gap with a magnetic fluid containing nanoparticles. By varying an external magnetic field, they controlled the optical properties of this fluid: its ability to interact with light, specifically its dielectric permittivity. This directly modulated the quantum Casimir pressure in the gap: by changing the medium's response to electromagnetic fluctuations, they could switch the force from attraction to repulsion. The plate hovered, held up solely by the quantum field.

Remarkably, levitation was achieved even at room temperature, even though thermal jitter, the chaotic motion of particles tied to entropy, tends to disrupt this delicate balance. The scientists calculated the critical threshold beyond which thermal fluctuations outweigh quantum ones and managed to overcome it through precise material tuning. The most surprising part: the finer the tuning of the components' optical properties, the higher the plate rose — by tenths of a millimeter, which, on the scale of the microworld, is comparable to flying several meters in our world. In other words, the "quantum glue" analogy simplifies the picture: in reality, it's a subtle interplay of electrodynamic forces in a nonequilibrium medium, but the essence holds, the vacuum can become a reliable support.