What kind of chain length differential is enough to cause people to switch. Is it a single block?
> Is it a single block?
No. The 'winning chain' is determined by total difficulty, not block count.
No. The 'winning chain' is determined by total difficulty, not block count.
At 51% you have more hashing power than the rest of the network combined, so you can start mining blocks on your own and create your own chain with the knowledge that eventually your chain will be longer than the 49% chain everyone else is working on. When that happens, the 49% will abandon their chain and start working on yours.