Antigravity

Antigravity refers to hypothetical mechanisms or technologies that would negate, counteract, or reverse the effects of gravity. In practical terms it would enable an object to levitate or accelerate upward without expelling propellant or relying on aerodynamic lift. No such device has been demonstrated.

In physics, gravity is described by general relativity as the curvature of spacetime produced by mass-energy. A genuine antigravity effect would require either negative gravitational mass or negative energy density, or a new interaction beyond established theory. The cosmological constant (dark energy) acts as a repulsive effect on cosmic scales but does not provide local gravity shielding.

To date, there is no verified laboratory demonstration of gravity shielding or true antigravity. Several high-profile claims (including reports of superconducting discs) have not been independently replicated or withstood scrutiny. Observed levitation effects in laboratories are typically due to magnetic forces, buoyancy, or other non-gravitational interactions.

Related topics include gravitomagnetism and frame dragging, which are small effects predicted by general relativity for moving masses but do not allow macroscopic antigravity. Some speculative theories consider negative mass or exotic matter, but none offer a practical antigravity device. Quantum field effects such as the Casimir effect do not enable macroscopic gravity cancellation.

In culture, antigravity is a common trope in science fiction and a frequent subject of speculation about future propulsion and space travel.