Bitcoin Forum

Bitcoin => Development & Technical Discussion => Topic started by: Stampbit on April 12, 2013, 03:30:17 AM



Title: Why is block creation limited to one every ten minutes?
Post by: Stampbit on April 12, 2013, 03:30:17 AM
My googlfu has failed me, i cant seem to find why exactly block creation is limited to one every 10 minutes, can someone explain this?


Title: Re: Why is block creation limited to one every ten minutes?
Post by: Maged on April 12, 2013, 03:36:40 AM
A good question. Fortunately, Satoshi answered it while he was still around:

https://bitcointalk.org/index.php?topic=134451.msg1432372#msg1432372
Quote from: satoshi
Quote from: Mike Hearn
Another is the 10 minute block target. I understand this was chosen to allow transactions to propagate through the network. However existing large P2P networks like BGP can propagate new data worldwide in <1 minute.

If propagation is 1 minute, then 10 minutes was a good guess.  Then nodes are only losing 10% of their work (1 minute/10 minutes).  If the CPU time wasted by latency was a more significant share, there may be weaknesses I haven't thought of.  An attacker would not be affected by latency, since he's chaining his own blocks, so he would have an advantage.  The chain would temporarily fork more often due to latency.


Title: Re: Why is block creation limited to one every ten minutes?
Post by: deepceleron on April 12, 2013, 03:37:56 AM
It's magic sauce, too many an hour and orphan block chances increase and individual block difficulty decreases, too few an hour and it takes too long to establish a trustable probability of blocks.


Title: Re: Why is block creation limited to one every ten minutes?
Post by: Maged on April 12, 2013, 03:40:49 AM
Related:
https://bitcointalk.org/index.php?topic=6373.0
https://bitcointalk.org/index.php?topic=4382.msg67351#msg67351


Title: Re: Why is block creation limited to one every ten minutes?
Post by: Stampbit on April 12, 2013, 03:45:23 AM
Thanks that makes sense.


Title: Re: Why is block creation limited to one every ten minutes?
Post by: gmaxwell on April 12, 2013, 04:23:02 AM
A useful way of thinking about it is this:  What would happen if the block time were infinitely small but latency was not?    Nodes would all have solved their own new block before a block from a peer showed up— each node would be its own network never (or at least infrequently) to converge with anyone else.

The same applies for speeds which are fast compared to latency:  They cause long delayed convergence events.  The particular number for 10 minutes is debatable... there is nothing that gives you that particular value .. it's just a security/scalability/network-radius vs confirmation speed tradeoff.

The infrequent blocks also keeps costs down on lite nodes which must process all the headers.



Title: Re: Why is block creation limited to one every ten minutes?
Post by: Stampbit on April 12, 2013, 04:47:08 AM
A useful way of thinking about it is this:  What would happen if the block time were infinitely small but latency was not?    Nodes would all have solved their own new block before a block from a peer showed up— each node would be its own network never (or at least infrequently) to converge with anyone else.

The same applies for speeds which are fast compared to latency:  They cause long delayed convergence events.  The particular number for 10 minutes is debatable... there is nothing that gives you that particular value .. it's just a security/scalability/network-radius vs confirmation speed tradeoff.

The infrequent blocks also keeps costs down on lite nodes which must process all the headers.



I found a post you made recently that i thought was interesting:

Quote
…Not to mention a zillion other less workable ideas that are waiting for some breakthrough or another to make viable… mostly I try to spare the public the more inane stuff... and certainly I've had no shortage of imagination for all the technical and economic failure modes that can result from removing part of the scarcity that drives a cryptocurrency.  We've even had non-blockchain scarce altchains— Liquidcoin (for speculation)—, perhaps you don't remember because it imploded into complete non-convergence before half the people who wanted to run it even got it installed (though its 'innovation' was uncapping the block rate instead of uncapping the blocksize).

So by lifting the block generation rate this currency imploded? neat.