[ballenf]

Does this mean that the second block from a random point in time is, on average, 20 minutes away?

Anyone know what the longest wait time on a block in recent history was?

Final question -- do large mining operations network their miners so that they don't overlap their hashes. I'm thinking the overhead in doing that would probably be counter-productive given the massive problem space. But, if they were networked that then the probability would eventually go down for a long enough wait between blocks (assuming there exists some massive mining operation).

[contravariant]

> Does this mean that the second block from a random point in time is, on average, 20 minutes away?

No, under the assumptions in this article the next block is on average 10 minutes away.

The paradox is that at any random point in time the previous block will also have been, on average, 10 minutes ago. Meaning that if you pick a random point in time and wait for the next block then on average you'll wait for 10 minutes, but the block will have taken 20 minutes in total to mine. Despite the fact that blocks are only supposed to take 10 minutes on average.

[tlrobinson]

> do large mining operations network their miners so that they don't overlap their hashes

Interestingly, it's hypothesized that Satoshi did this:

> He suggested that Satoshi had access to 58 machines for mining, so to avoid checking the same nonce twice he gave each machine a different id, which was stamped in the LSB of the nonce.

https://bitslog.wordpress.com/2013/09/03/new-mystery-about-s...

[gtrubetskoy]

> do large mining operations network their miners so that they don't overlap their hashes

The short answer is "no" (there is no need).

The SHA-256 space (2^256) is larger than the number of atoms in the observable universe, if you pick the (extra)nonces at random, there is practically no chance you can ever pick the same number as anyone else.

[sebbyBinx]

There was a 1.5 hour gap after this block:

https://blockchain.info/block-height/152217

[branx]

I'm confused...it says the Block Reward was 50BTC but I thought that miners are only supposed to get 1 per block?

[xyzzyz]

> Final question -- do large mining operations network their miners so that they don't overlap their hashes.

There is no need to do it -- if each miner has a source of true randomness, then it's enough that each miner randoms large number (how large, depends on the number of miners, see the birthday paradox), and slap it on to "salt" their block. If the number space is large enough, it is unlikely that two different miners will get the same salt.

[tobiaswk]

With bitcoin (not bitcoin cash) the difficulty is adjusted every 2016 blocks. If too many blocks were mined in this period the difficulty will decrease and vice versa. This means that many blocks could be mined faster or slower in this period. Until of course the difficulty adjustment occurs again.

You use what is called the nonce in the block header. Each time you do a hash of the block you increment this nonce. If your hash is under or equal to the difficulty the block is valid. The difficulty essentially means how many zeroes are in front of your hash.

What big mining operations do is to slice this nonce into appropriate ranges for each miner. So no miner is hashing with the same nonce. So miner 1 starts at nonce=0 and miner 2 on nonce=2000. The nonce range depends on how many hashes each miner can do in a ten minutes span. By doing this each miner is not doing hashing with the same nonce. That would be wasting hashing operations.

Now bitcoin cash changed the difficulty adjustment algorithm (DAA). Instead of adjusting the difficulty every 2016 blocks this is done after each block has been found. This was done to stabilize the difficulty. So miners stay mining bitcoin cash instead of switching between the most profitable chain (bitcoin or bitcoin cash). This was a problem before the new DAA was implemented for bitcoin cash.

There has been times in recent history were no new block was found for 20 minutes on bitcoin. For bitcoin cash around 2 hours. This was in November 2017. It has been 10 minutes stable ever since.

You can check this yourself on bitinfocharts.com for each blockchain under Block Time.

[viraptor]

You can see the whole history at https://bitinfocharts.com/comparison/bitcoin-confirmationtim...