Banned for explaining an apparently nonfunctional way to back up a universe.
I *think* this would work, though:
1. Split the time stream somehow. Flipping a coin should do it; if not, measure the spin of some random proton or electron (which will be +1/2 or -1/2). According to the "many worlds" interpretation of quantum mechanics, any time some event could happen one way or another (such as a quantum coinflip), the universe actually splits, creating one universe in which it comes out heads (or +1/2) and another in which it comes out tails (or -1/2).
2. Remove all worlds in one of the split time streams from that time stream, so no time appears to pass on any of them. That's how phasing works, right?
3. Let the other time stream evolve normally until someone breaks it.
4. Phase all the phased-out worlds in the first stream back in. Again, that's how phasing works.
5. Let this time stream evolve until just before whoever broke the last one.
6. Do whatever you do to make a universe not break when that person divides by zero.
7. Rinse and repeat.
This way, the only difference between the two streams (before breaking) is the state of your coin. But nobody's ever going to see that, so who cares? Also, if anyone does, they won't see it change suddenly- if they see it as heads, it had always been heads in that universe; if they see tails, it had always been tails.
Which all leaves only one thing:
8. Set up a script to automate steps 1-7.