By the power of truth, I, while living, have conquered the universe.
Posted by: TopWargamer
Marathon and Halo are in the same universe
Marathon and Halo are not in the same universe. Marathon has a completely different canon to Halo, it has been stated by Bungie themselves that Halo and Marathon aren't the same.
I'm slightly amused and at the same time saddened that so few people are interested in looking for an answer to the question of why Marathon and Halo can't be the same universe beyond "because Bungie said so". Particularly because there are precise contradictions which clearly illustrate that both stories cannot simultaneously coexist in one universe. The two most common and most damning contradictions are found in technologies unique to each universe.
FTL Travel
The first contradiction involves the technology of faster than light travel. Everyone knows that in Halo, FTL travel is possible by using Slipspace. According to the Halo timeline, the Shaw-Fujikawa Translight Engine was created in 2291. By 2310 FTL travel was being used to start colonies. By 2390, colonization of the Inner Colonies was fully underway. By 2468, Outer Colonies were being settled. By 2490, the colonization boom was well underway and human space encompassed more than 800 worlds.
A quick study of Marathon's timeline will reveal a very different story. The conversion of Mars' moon Deimos into the Colony Ship Marathon began in 2408. It was completed 64 years later in 2472. It took the Marathon 300 years to travel from Sol to Tau Ceti (a distance of 12 light years). Obviously the Marathon was not equipped with FTL travel capability.
It is unconscionable that a colony ship would be built without FTL travel capability 117 years after the discovery of the FTL travel engine and during the golden age of FTL travel driven space exploration and colonization. Therefore it is not possible that the Halo and Marathon stories exist in the same universe.
Teleportation Technology
According to the Marathon timeline, teleporters began to be used in Sol as early as 2319. The Marathon, which was constructed from 2408 - 2472 was equipped with teleportation technology.
In the Halo universe teleportation technology was still unknown to humanity in 2552, 233 years after it was being used in Sol in the Marathon universe.
FTL travel and teleportation technologies are both unique to their respective universes and of primary importance in the telling of each story. These technological contradictions are irreconcilable, and therefore prove that the Marathon and Halo universes cannot be one in the same.