Why bitcoin?
Why not 'regular money' that more people have?
Why not 'regular money' that more people have?
Actually that's not it. What I'm saying is that you can have any normal multi-party signature scheme, where every N signing-rounds you ensure some measure of canonical ordering by publishing the hash in the bitcoin blockchain. I think sidechains are probably formulated in a similar fashion but it's been a while since I've looked at exactly what they are doing, the trickier parts if I remember correctly are transfers of value on and off the original chain.