I can't believe the number of people that are hung up on "how big the galaxy is, how much time it would take to travel." You do realize the Relays are pure fiction, yes? An author can invent any form a transport that he wants. FTL is simply not possible in the real world as far as we know. So any type of transport can be invented that accomplishes the goal of rapid travel across the galaxy. Reorte gets to the core function of the relays:
The question is not whether they are necessary from a "scientific point of view" since they are purely fictional, but whether they are necessary for the MEU to be ME. My feeling is that while they are iconic, they are not essential.
You completely missed the point. Dg explains the point to you in his post above. It has nothing to do with real life physics, it has to do with how the fictitious universe of mass effect is supposed to work. You can't just invent whatever the hell you want, then there is no point in attempting to construct a coherent, fictional universe and it goes from sci-fi to straight up fantasy where magic reigns supreme and you can create any plot device you want to make up for your shitty writing.
Also, technically FTL travel is even impossible in Mass Effect. No ships truly travel faster than light in a vacuum, they are effectively (keyword effectively) travelling faster than light as the speed of light is no longer considered a constant in Mass Effect. Ie: Within the bubble of decreased mass surrounding a ship, the speed of light has been increased to a much greater value. The ship never gets anywhere close to reaching the new speed of light. That's why it negates relativistic effects. It's rather cleverly thought out.
And just because I'm in the mood to be a contrarian, technically effectively (keyword effectively) travelling faster than light is not even impossible by our understanding of physics today. I mean ****, General Relativity predicted wormholes a hundred friggin years ago, and the Alcubierre drive is mathematically coherent and plausible (although exotic matter may not be physically possible). It's not like these are new ideas or anything.
Todays science fiction is tomorrows science fact.