I asked ChatGPT some questions about BIP300:

============================ Q:

Let's pretend that we create a sidechain on Bitcoin using BIP300, and this sidechain is an identical instance of the Bitcoin protocol itself except starting with a completely new block history from block 0. This new sidechain will need to record transactions. Wouldn't the sidechain begin to grow in size just like the original Bitcoin chain, and thus, if we're wanting to maintain both chains, the node would grow to be double the size requirements as compared to just running one?

A:

Yes, if a sidechain created using BIP 300 is an identical instance of the Bitcoin protocol with its own block history, it would indeed grow in size, and running both the main Bitcoin blockchain and the sidechain on a single node would require more storage space compared to running just one of them.

In such a scenario, each chain (the main Bitcoin chain and the sidechain) would maintain its own separate blockchain with its transaction history, blocks, and associated data. Both chains would continue to grow over time as new transactions are added to their respective ledgers.

Therefore, if you wanted to maintain both chains and run a node that supports both the main Bitcoin chain and the sidechain, you would need storage capacity for both blockchains. The combined storage requirements would be approximately double the size of running just one chain.

It's important to note that the specific storage requirements would depend on factors such as the frequency and volume of transactions on each chain and any additional data that the sidechain may store. As a result, the actual storage needs for running both chains may vary over time.

Additionally, running a node for a sidechain, especially one that is designed to be a near-identical instance of the Bitcoin protocol, would involve synchronization with both the Bitcoin network and the sidechain network, which can have its own resource and bandwidth requirements. Properly maintaining and syncing multiple blockchains can be resource-intensive.

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That sounds like BCash with extra steps.

Are we expecting nodes to support all sidechains? My node is already stretched super thin on resources. The UTXO set is growing so fast, mempool is big, and disk space is a never-ending concern.

And if we're NOT expecting nodes to support all sidechains, then what's the point of having this on Bitcoin? Like, it seems simpler to just let the resources be used separately as it's own altcoin or hard-fork.

If we're talking about a sidechain like a copy of zcash or Monero, since they use a different hashing algorithm, we couldn't use merged mining right? Would they be converted to Scrypt? If not, then again, miner resources couldn't be recycled and then what's the point? Again, it seems simpler to just use an altcoin or hard-fork.

I mean, what is Bitcoin if it's not the collection of it's protocol, nodes, and mining power? If nodes and mining power can't be leveraged, and instead, have to be sacrificed to support different sidechains, what do we end up with? It seems like a fractured architecture - but I've only briefly skimmed this BIP300 stuff so far.