What would stop some from creating a secondary BTC blockchain?

[OneEyedJack]

What would stop some from creating a secondary BTC blockchain?
I mean, in theory, all we are doing is solving transaction puzzles to generate Bitcoins.

So, what would stop someone from creating a new blockchain based on Bitcoin and allowing people to mine it for BTC?

Or did I miss something on the security of the Bitcoin blockchain?

I mean if people can create alt coins, then why can't they create another BTC?

[trace666]

That would be an altcoin. Transactions would not be compatible with the existing blockchain.

[Holliday]

This has already been done. An alt-coin which was an exact copy of Bitcoin. I don't think it lasted very long (I could be wrong).

[DannyHamilton]

Or did I miss something on the security of the Bitcoin blockchain?

You missed the part where there are no "actual" bitcoins.  All that exists are transactions that are stored in a blockchain.

If you create a new blockchain, then it will have it's own transactions.  Those transactions won't exist in the bitcoin blockchain (and vice-versa).  Therefore, they won't be "bitcoins" , they'll just be alt-coins that have the same protocol rules as bitcoin.

There won't be a way to send a transaction from your blockchain to the bitcoin blockchain, since in order to be valid EVERY bitcoin transaction must contain a reference to previous unspent transaction outputs elsewhere in the bitcoin blockchain.