Light bridge

"I’m showing a lot of photonic activity. The excited photons have displaced the air around the light path." "Which means?" "Which means that the light has become coherent. Solid."

- Exchange between John-117 and Cortana

Energy bridges, also known as light bridges, are examples of advanced Forerunner technology. They use hard light technology to function.

Summary
There are usually two components to an energy bridge: a control panel, and the light emitters. The control panel is a semi-translucent holographic array of Forerunner symbols and glyphs that are projected over the surface of a pedestal. Though a variety of control panel configurations have been observed, in the case of one of the energy bridges on Installation 04, tapping the "blue-green circle" activated the light emitters.

A cascade of coherent, high-energy photons are emitted through the air, generating a visible, horizontal band of light. Through unspecified physics, the coherent band of light interacts with the illuminated air, and pushes aside the air within and around it it, becoming a firm, solid mass capable of supporting extremely heavy weights, ranging from a M12 Warthog LRV to several M808B Scorpion MBTs. When damaged, the emitters flicker on and off, causing the light bridge to flicker, creating a less stable force.

Energy bridges are commonly seen on most Forerunner constructs. The Forerunner complex on Harvest featured energy bridges crossing over a series of chasms surrounding the center of the main chamber. These were used by the UNSC forces as they made their way in and out of the facility during the Harvest Campaign in 2531. Shield 0459, discovered by the in the same year, had a multitude of energy bridges to span chasms within its interior. Unlike most energy bridges encountered by the UNSC, which manifested as simple beams of blue-white light, these energy bridges featured arrangements of lines forming symmetrical, geometric patterns characteristic of Forerunner art and architecture.

Energy bridges were used by John-117 during the UNSC's operations on the surface of Installation 04, in the subterranean complexes and the Flood containment facility. Though mainly unseen on Installation 05, they were also present on the Ark, again in a subterranean area, and another one at the entrance to the Citadel near the Ark's Core.

Trivia
There are four energy bridges in the Halo trilogy. The first and second are the bridges on the level Halo, and the bridges on the level 343 Guilty Spark from Halo: Combat Evolved, the third being the one on the Ark on the level The Ark in Halo 3, and the last being the one in the Citadel on The Covenant.

List of appearances

 * Halo: Combat Evolved
 * Halo 3
 * Halo Wars
 * Halo: The Flood