It isn't explained in the game itself.
You must remember that the AC franchise is ripe with fictional "technology" that isn't explained.
- How does the Animus tap into the memories of our ancestors that are stored in our D.N.A?
- How does the Apple control human minds?
- How can subject 16's consciousness live inside the Animus?
Even the way that a really big solar flare suppose to kill all humans and gods on Earth but leave other life forms alive, which is the premise for the whole plot isn't explained.
And many other examples. The AC franchise doesn't stop to explain the mechanics working behind the scenes, and we are left with a simple explanation of "It just works, stop asking so many questions and go kill some Templar scumbags".
In fact, the end of the world is simply a MacGuffin used to move the plot forward, and as with many other MacGuffins, it isn't fully explained. (What is inside the briefcases in Pulp Fiction and Ronin?)