Can the BTC developers just cut the blockchain in half to save memory space?

[Capitalism Prevails]

Or would that mess up the network?  Isn't the full block chain needed to show proof of work for each BTC?

[DeathAndTaxes]

Or would that mess up the network?  Isn't the full block chain needed to show proof of work for each BTC?

No you can't just cut the blockchain in half.

Full nodes need a full and complete copy of the blockchain back to genesis block.
Slightly less security is a full node with pruned copy of the blockchain.
SPV (lite clients) don't need a full or even pruned copy of the blockchain.

So there are options going forward but someone, somewhere (and preferably a couple hundred "archive" nodes) need a full complete copy of the blockchain.

[Capitalism Prevails]

Don't light clients sacrifice a little decentralization of the network in order for them to operate?

[wolverine.ks]

why couldnt there be a btc clone with a genesis block identical to the some other block half way up the current chain? or the most recent block for that matter?

wouldnt that essentially be what OP was saying?

[Capitalism Prevails]

Well it just seems to me that would be a short term fix if Bitcoin really takes off.

[OnkelPaul]

why couldnt there be a btc clone with a genesis block identical to the some other block half way up the current chain?

Because to check whether some transaction is valid the nodes need to look at the blocks with the transactions whose outputs are inputs of the new transaction.
Every unspent output needs to be visible. IIUC, it would be theoretically possible to "prune" the blockchain and remove all transactions whose outputs have been spent.
However, to do such a thing would require messing with the blockchain a lot, including finding a way to represent the prevblock hash which forms the link between each block and the one it builds upon.
Fot BTC, just forget it. A new cryptocurrency could have a different blockchain format which would enable the network to drop old data. I think the ripple ledger format is designed to do that, however I've not looked closer to see whether that is currently possible or just a future option.

Onkel Paul

[Capitalism Prevails]

why couldnt there be a btc clone with a genesis block identical to the some other block half way up the current chain?

Because to check whether some transaction is valid the nodes need to look at the blocks with the transactions whose outputs are inputs of the new transaction.
Every unspent output needs to be visible. IIUC, it would be theoretically possible to "prune" the blockchain and remove all transactions whose outputs have been spent.
However, to do such a thing would require messing with the blockchain a lot, including finding a way to represent the prevblock hash which forms the link between each block and the one it builds upon.
Fot BTC, just forget it. A new cryptocurrency could have a different blockchain format which would enable the network to drop old data. I think the ripple ledger format is designed to do that, however I've not looked closer to see whether that is currently possible or just a future option.

Onkel Paul

So you think its impossible for the BTC developers to upgrade their code so the ledger could be pruned?