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Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

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Re: Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

#11

Post by [deleted] »

hexane360 wrote: post #6
zaroth wrote: post #3

Earlier quoted context omitted.

This is like a common core math problem. Poorly worded to the point of obscuring any real math talent that could be applied in finding a “correct” result, and instead we get to debate what the question means . A more interesting question, I think, is given a POW algorithm which adjusts difficultly to target a 10 minute block rate, and assuming network hash rate is constant and propagation is instant, what percentage…

Can you explain the multiple meanings you see in the question?

[deleted]

Re: Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

#12

Post by travisjungroth »

alschwalm wrote: post #5

The article on the "hitchhiker's paradox" that this links to made this much more clear to me (as well as being shorter): https://the8layers.com/2016/10/30/how-long-will-you-wait-hit...

This reminds me of headwinds in airplanes. You might think that on average, wind cancels out. Sometimes you have a tailwind, sometimes you have a headwind and over time it will all average out. This is not the case.

On average, wind reduces your groundspeed. The short of it is you spend more time in a headwind, so you spend more time experiencing the bad than good.

There's also the fact that even a direct crosswind slows down you ground speed (you lose some speed for correcting your course) but I don't think this compares to block chains or hitchhikers.

Re: Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

#14

Post by 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).

Re: Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

#15

Post by [deleted] »

ballenf wrote: post #14

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…

[deleted]

Re: Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

#16

Post by viraptor »

ballenf wrote: post #14

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…

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

Re: Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

#17

Post by xyzzyz »

ballenf wrote: post #14

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…

> 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.

Re: Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

#18

Post by rory096 »

SilasX wrote: post #9
nosuchthing wrote: post #7

Bitcoin mining = "Guess a random number between 1 and 5" If the network guesses too fast due to more cumulative guesses per second, the target number increases. Interesting historical antidote, in early November of 2017 there was an event where it became more profitable to mine Bitcoin Cash. During that time about 60% of the miners left BTC Core in unison to focus on BTC Cash. Transactions for BTC Core started taking…

BCH is frequently more profitable than BTC -- the mining power constantly oscillates between the two. Checkout fork.lol which tracks DARI, an estimate of the profitability of mining the coin, you see how the more profitable one frequently switches: https://fork.lol/reward/dari/btc

This is of course not surprising - in the long run all difficulties (for similarly hashed coins) should trend towards equalizing profitability lest they create an arbitrage opportunity. The driving factor in the grandparent's case was the short-term spike in BCH after it was listed on Coinbase.

Re: Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

#19

Post by contravariant »

ballenf wrote: post #14

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…

> 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.

Re: Why Is It Taking 20 Minutes to Mine This Bitcoin Block?

#20

Post by sebbyBinx »

The timing of block arrivals also greatly affects the guarantees against double spending, so this paradox may have some security implications.

Accepting transactions blindly after 5 confirmations/blocks throws away the information of the amount of time it takes to generate those blocks

https://eprint.iacr.org/2018/040

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