Artificial gravity
From Halopedia, the Halo wiki
Artificial gravity is a range of technology employed by sentient races in the Halo universe.
Centrifugal Motion
Before contact with the Covenant, Halo: The Fall of Reach states that humans used rotating sections in their spacecraft to simulate the gravity of a planet. They would function by pulling objects to their outer edges as they turned. This technology is a potential option for future space missions in real life.
Covenant Artificial Gravity
The Covenant employ some form of gravity on their spacecraft which does not rely on rotation in its operation. It is an illustration of the traditional 'artificial gravity generator' seen in other sci-fi such as the television series Star Trek. This technology was eventually reverse engineered by the UNSC who apparently rapidly constructed an entire new line of spacecraft build around it.
In current times, the only technology which could resemble that used by the Covenant is known as diamagnetics. Every object has a magnetic attraction, although most are very weak. Diamagnetics involve taking advantage of this attraction using intense magnetic fields. However, such fields would not be healthy in the long term. It is more likely that the Covenant utilise some principle which has little basis in real-life science.
Discrepancies Regarding Artificial Gravity
The first of such problems concerns whether the UNSC possessed non-centrifugal artificial gravity before contact with the Covenant. Certainly, the Pillar of Autumn was designed with artificial gravity in mind, but its class was first comissioned twenty-one years before the start of the Human-Covenant War.
Halo: Contact Harvest also illustrates that human DCS freighters were equipped with some form of gravity. Although this may be based around rotation, description of the craft in the book appears to suggest that some form of generators are employed.
It is possible that in 2525 (when Halo: Contact Harvest takes place), the antigravity plates seen in Halo: Ghosts of Onyx were undergoing trial runs. It seems plausible that like General Howard Graves of the URF said, the plates were taken out of use shortly after 2525.
