[dlubarov]

10 minutes was Satoshi's very rough guess at what a reasonable compromise might be. He didn't have any empirical data and probably didn't give it much thought. Since then we have some real data about propagation times, e.g. [1], and most other blockchains have chosen much faster block times, like ~12s for Ethereum.

[1] http://www.tik.ee.ethz.ch/file/49318d3f56c1d525aabf7fda78b23...

[jron]

Ethereum's security model is totally different: https://eprint.iacr.org/2016/555.pdf If you look at bitcoin based POW intervals, 10 minutes is very close to optimal: https://eprint.iacr.org/2015/1019.pdf

[dlubarov]

According to figure 2 in your second link, a blockchain with 1.5 rounds per block (or one block every ~19 seconds, based on their round length estimate) can withstand at least 40% hash power attacks. That seems like a reasonable tradeoff to me.

If you think 40% is not good enough, okay, let's target 48%. That's still just ~6.5 rounds per block (~82 seconds per block). Bitcoin's parameter of ~47 rounds per block is clearly overkill; the authors' graphs don't even go that far out (see figure 3).

Interestingly, the first paper you linked mentions that although Ethereum was intended to use single-level GHOST scoring, uncle blocks aren't actually counted toward chain difficulty, so it really has the same security model as Bitcoin. This was also confirmed by an Ethereum dev [1].

[1] https://ethereum.stackexchange.com/a/13750