In Star Trek, a Graviton Ellipse was a stable pocket of normal space moved by a surrounding elliptical concentration of graviton particles, called gravimetric distortions. The graviton is an elementary particle that transmits the force of gravity. It is used for a variety of purposes involving attractive/repellent forces, such as tractor beams, the gravity plating on starships or antigravs. The opposite of a graviton is an antigraviton.

Graviton ellipses traveled through subspace. Emerging into normal space and extra-dimensional realms only when they were in proximity of objects that emited electromagnetic energy, such as spacecraft and dark matter asteroids. The ellipses themselves generated an electromagnetic radiation field, of dangerous levels to humanoids, that made the anomaly react like a magnet drawn to another magnet, relative to it's target.

One such graviton ellipse, with a perimeter over a kilometer in diameter, had been in existence from the time of the formation of the Milky Way Galaxy. It was found to have devoured objects from all of the quadrants of the galaxy. In 2032 this anomaly emerged in the Sol System and devoured the Ares IV Mars orbiter. This was mankinds first encounter with a spatial anomaly. The same ellipse attempted to devour USS Voyager, in 2376, in the Delta Quadrant. Commander Chakotay suggested the anomaly to be renamed as the "kitchen sink anomaly" due to the debris field contained inside. Graviton ellipses have been observed only a handful of times, and no known ship has ever survived the encounter or escaped being devoured, before the Voyager. (VOY: "One Small Step")

In actual physics, the graviton is indeed a hypothetical elementary particle that mediates the force of gravity in the framework of quantum field theory. Gravitons are postulated because of the great success of the quantum field theory (in particular, the Standard Model) at modeling the behavior of all other forces of nature with similar particles: electromagnetism with the photon, the strong interaction with the gluons, and the weak interaction with the W and Z bosons. In this framework, the gravitational interaction is mediated by gravitons, instead of being described in terms of curved spacetime as in general relativity. In the classical limit, both approaches give identical results, which are required to conform to Newton's law of gravitation. String theory also predicts the existence of gravitons.

However, attempts to extend the Standard Model with gravitons run into serious theoretical difficulties at high energies (processes with energies close to or above the Planck scale) because of infinities arising due to quantum effects. Some proposed theories of quantum gravity (in particular, string theory) address this issue. In string theory, gravitons (as well as the other particles) are states of strings rather than point particles, and then the infinities do not appear, while the low-energy behavior can still be approximated by a quantum field theory of point particles. In that case, the description in terms of gravitons serves as a low-energy effective theory.

Unambiguous detection of individual gravitons, though not prohibited by any fundamental law, is impossible with any physically reasonable detector. The reason is simply the extremely low cross section for the interaction of gravitons with matter. For example, a detector the mass of Jupiter with 100% efficiency, placed in close orbit around a neutron star, would only be expected to observe one graviton every 10 years, even under the most favorable conditions. It would be impossible to discriminate these events from the background of neutrinos, and it would be impossible to shield the neutrinos without the shielding material collapsing into a black hole.

However, experiments to detect gravitational waves, which may be viewed as coherent states of many gravitons, are already underway. Although these experiments cannot detect individual gravitons, they might provide information about certain properties of the graviton. For example, if gravitational waves were observed to propagate slower than the speed of light in a vacuum, that would imply that the graviton has mass.