90 minutes to send cash, anywhere in the world, without needing a third party? That is amazing!
in fact the bitcoins were not reversible the the second they were send.it just took 90 minutes to confirm it was a good tx.
I wonder that the odds are for a 90min block?
imagine we get really unlucky and hit a 3 year block
Assuming a constant hashrate:
-The probability that a block won't be found after 10 minutes is 50%, or .5.
-The probability that a block won't be found after 20 minutes is .5 * .5 = .5 ^ 2 = 25%.
-The probability that a block won't be found after 90 minutes is .00195, 0.2%, indicating 1-in-512 blocks can be expected to take 90 minutes or more (averaging about one in four days with long-term sampling)
-The probability that a block won't be found after one day of mining is .5 ^ 144 = 0.000000000000000000000000000000000000000005%
We need a feedback mechanism to minimize very long rounds (and less importantly, very short rounds). ....
The term "rounds" is only used in pools to describe the periods between their block finds and the work/reward evaluation time.Being able to alter the target difficulty based on included transactions (theory omitted from quote) is unacceptable; a miner could just pad his own valueless transactions in a block up to the maximum block size; everybody would be making 500K blocks and bloating the blockchain with faster-than-expected blocks.
The system now is perfect: miners have a financial incentive to include as many fee-paying transactions as possible, and a disincentive to include free transactions (as a larger block increases the risk of an orphaned block by making block propagation time longer). This keeps cruft out of the blockchain.