Anti-gravity tables explained

We expect a table to have legs. After all, how else can it support the top in its position? The idea of replacing legs with chains seems absurd. We use chains to suspend a chandelier from the ceiling. And we can't suspend a table from the floor unless, by some magic, we reverse the direction of gravity. Yet, anti-gravity tables appear to do just that, giving the impression of floating in the air (Fig. 1). The trick is that their clever design makes gravity keep a tabletop elevated by pushing it down.

Fig. 1  The anti-gravity table looks like it is floating in the air.

Gravity is always strongest at the Earth's surface, pulling all objects toward it. A chandelier may look like it is supported by a chain hanging from the ceiling. But in fact, support comes from the walls resting on the ground. Similarly, all table's components are supported by the lower part touching the floor (Fig. 2), with the top hanging from it like a chandelier from the ceiling, with one distinction. For chandeliers, all their parts are positioned below the ceiling attachment point. In our case, however, the section above the chain makes the equilibrium unstable.

Fig. 2 The top section of the anti-gravity table is suspended from the bottom section by a chain.

The instability problem is resolved with the help of the remaining four chains. The two chains on the right (Fig. 3) stop the left side of the tabletop from dropping to the floor. Likewise, the two chains on the left will keep the right side elevated. This combination completes the design, enabling the structural stability of the table as a functional piece of furniture.

Fig. 3  Two chains attached to the right end secure the elevated position of the left end.

The weight of the tabletop is counterbalanced by the tension in the chains, which are carefully adjusted in length to ensure maximum stability. This concept, known as tensional integrity or tensegrity, is used in engineering to create stunning architectural structures that appear to defy gravity. One example is the Kurilpa Bridge in Australia, the world's largest tensegrity bridge with stainless steel tensegrity cables (Fig. 4). This jewel of modern engineering also features a sophisticated solar-powered lighting system programmed to illuminate it in various colors at night.

Fig. 4  Kurilpa Bridge in Brisbane (Queensland, Australia) is the world's largest hybrid tensegrity bridge. Source: Wikipedia