I have a limited understanding of the physics of it, but as far as I know time dilates at higher velocities. Meaning that time essentially passes slower for objects moving at higher velocities. Why don't FTL travelers using Mass Effect Relays experience this?
If you take special relativity literally, any object observed to be travelling faster than light in one frame can be shown to be not moving(in time) in another frame and traveling backward(in time) in a third frame. Any universe that features faster than light (FTL) travel does not use the physics of our universe. Or if it does, it has to deal with the time travel aspect of FTL travel.
It's safe to say that either:
1) The mass effect speeds are not really faster than light speeds, but only talked about that way in-game.
2) The physics of the game universe are not the physics of our universe.
It has somthing to do with the "mass effect". I believe It is explained in game. Basically the mass effect field not only makes it possible to travel FTL but it also allows you to harness negative energy which in turn bends space and time into a "pretzel" which basically prevents time dilation. Here is a link to a physicist who can explain it better:
Dr. Michio Kaku is one of the top physicist in the world.
Here is some more info:
"Cosmic strings: Another theory for potential time travelers involves something called cosmic strings — narrow tubes of energy stretched across the entire length of the ever-expanding universe. These thin regions, left over from the early cosmos, are predicted to contain huge amounts of mass and therefore could warp the space-time around them.Cosmic strings are either infinite or they’re in loops, with no ends, scientists say. The approach of two such strings parallel to each other would bend space-time so vigorously and in such a particular configuration that might make time travel possible, in theory."
Mass Effect fields work by reducing the mass of anything inside that field. This removes any mass based time dilation, at rest or while moving. With typical relativistic travel, the faster you go, the more energy you need as your mass increases while moving. By reducing that mass to near zero, you reduce energy needs.
But Mass Effect fields also have another effect, as it were. It effectively raises the speed of light, C. As that also changes, the ship inside the field would still be traveling at a low fraction (relative)C, and not experience time dilation from massless high velocity alone.
While I'm not certain, I would think it's because the ships have no mass at all (biotic lifts demonstrate this happening on the battlefield). I'm no physicist, but I would think that relativistic effects are dependent on the amount of energy used to propel something- and with no mass, no energy would be required to propel it. Obviously there are still questions there.
As Prototypetolyfe says, the studio didn't cover this, possibly because it's a lot of trouble, and possibly because you're getting into territory noone has crossed.
And Jakab, spoiler: the Protheans didn't invent Mass Effect technology.
Also, it's not just the relays; relays operate between clusters of stars, but ships in the ME universe all have FTL themselves. I assume the relays just go a lot faster.
There is no evidence that interstellar travel in the Mass Effect universe does not impose time dilation effects; the player never gets a real-time communication while moving at high-velocity relativistic speeds, and the ability to travel faster than light itself minimizes the time-debt. (If it only took me 20 subjective minutes in the citadel's frame of reference to traverse the galaxy, it doesn't matter if my own time frame had 20 subjective minutes or 2.)
For what it's worth, a mass effect that was able to remove a pure 100% of the mass from an object would not be sufficient to exceed c according to Einstein's theory of general relativity. It's not the speed that light just happens to travel; it's the maximum speed that any thing can move between two points. (QM funkyness notwithstanding, as QM begins with changing the meaning of "point", "move", and "thing")
I have no quote for this theory, but I always thought that it was because of the law of conservation of energy. Let's try a bit of math...
Remember the basic equation:
E = m·c2
Let the mass under a Mass Effect field be: me=k·m, being "k" the strength of the field.
But "E" must be constant in an isolated system such as a spaceship, so it is the light-speed that changes:
E = m·c2 = me·ce2 = k·m·ce2
ce = c·√k
Now, time dilation factor due to relativity is:
λ = √(1 - v2 / c2)
And under a Mass Effect Field:
λe = √(1 - v2 / kc2)
Or if you prefer:
λe = √(1 - (v/√k)2 / c2)
Imagine that you are willing to allow a 1% time dilation. The maximum speed, without a ME, would be about 42.000 km/s. But with a Mass Effect field of k=10-10 you can go up to 420.000.000 km/s. That's about 1400 times the speed of light!!