Bitcoin Forum

Either variance is fascinating or there's significant mining power being brought up.

https://i.imgur.com/0xAIKSe.png

BFL, is that you?

Uh oh...how long does it take for difficulty to go up?

another 900~ blocks

We regularly have an hour between blocks (usually after I send a transaction...) theres no reason that same variance can't cause 4 blocks to be found in a minute.

even if it's true, an hour is only 6 times longer than the average of ten minutes per block.

1/4 minutes is 40 times (shorter).

And they all happened to come from the same unknown person.

Putting that in numbers, 6 blocks an hour, so a 1 in 10 chance of finding a block in any given minute.

Chance of doing that in any given 4 consecutive blocks about 10*10*10*10 or 1 in 10,000, which isn't crazy rare. If we're going a touch faster because of growing capacity - which you'd expect as the price rises - even a small performance improvement improves those odds quite a bit, eg speed up from 1/10 chance per minute to 1/8 chance per minute (1 in 8*8*8*8 ) and the probability doubles.

Cavendish, Proctorsville, Vermont, 05153, USA

aparently

According to your numbers, on average this should happen every 10000 minutes /7days ?

Shit, that doesn't sound right, does it? Somebody else figure it out...

Rereading the OP it's 4 blocks all in the same minute, not 4 blocks in consecutive minutes, so it's going to be fair bit less, because they only get an average of 15 seconds not 1 minute.

If we accept "a 1 in 10 chance of finding a block in any given minute", that would imply there was 9/10 chances the event would occur during the other 9 minutes. We know it commonly takes longer than 10 minutes to find blocks so there is an error in logic somewhere. I'm confused now though.

It's really three blocks in a minute, since the first doesn't count - it was generated after 16 minutes.

So three blocks were generated in 0.1 x  expected time it takes to generate one block. Blocks arrival times probabilities are governed by the Poisson distribution.

You can calculate the CDF probability (http://www.wolframalpha.com/input/?i=CDF%5BPoissonDistribution%5B0.1%5D%2C+3%5D) of this occurring, but you need to assume a stable blocks per hour solve rate. This has been higher than one in ten minutes on average since difficulty began to increase, and since the start of this difficulty period it has been very low:


This changes our mean blocks solved in one minute to 1/7.852745 = 0.127344

So the CDF probability of three or more blocks occuring in one minute is slightly more likely than the previous estimate at 0.99999 (http://www.wolframalpha.com/input/?i=CDF%5BPoissonDistribution%5B0.127344%5D%2C+3%5D) - so three or more blocks occurring in one minute at the current block solve rate will probably happen once in every 100 000 minutes, or ~70 days.

Edit Since the hashrate has increased since one week ago, the blocks per minutes are likely a little higher than I estimated. That would make this occurrence more likely, although probably not much. I don't have the time to run an estimate at the moment, sorry.

if you're working out probabilities this might be important, use total number of miners to factor it in

The same node reported all 3 blocks, but received them from different sources.


The difficulty increases with the hashing power of the miners. This is why just the current block rate was needed to calculate the odds of 1 such event in 70 days.

you guys need to go one step further
http://blockchain.info/tx/e4dc4da69e06de3439c31d45463c57c9d94c245a172d7a318b570f65821a3ab4

CoinBase
03387603062f503253482f049050495108f800713656000000122f6f7a636f696e4075737374726 174756d2f
(decoded) 8v/P2SH/�PIQ�q6V/ozcoin@usstratum/

most pools are now tagging coinbases
blocks 226871 and 226872 were mined by Ozcoin

226870  was 50BTC
CoinBase
033676030004fa75031a0400000000522cfabe6d6d00000000001c93c8660000000000486920667 26f6d2035304254432e636f6d2035ac1eeeed88
(decoded) 6v�uR,�mm��fHi from 50BTC.com 5���

and 226869 was EMC
CoinBase
033576030651495028090afabe6d6d7ebf280cc05b6ff189621e50b69d21ae6171fc4b73a00e3d1 f9421fb09a27b3d010000000000000000454d43205553310050f8140600000000b20e0000
(decoded) 5vQIP(    �mm~�(�[o�bP��!�aq�Ks�=�!�   �{=
EMC US1P��

which of those is unknown?

oh and variance is fascinating, one day Ozcoin got 6 network blocks in a row 2 days later we had a round that went 9 xD and 40M+ shares, fun times :)

Blockchain.info was bugged.  I think 3 or 4 of those Unknown blocks were BTC Guild.  Blockchain.info was failing to parse the coinbase transaction properly, thus the negative fee.

 ::) Facepalm, obviously it was a parse error you guys. Nobody in Vermont is smart enough to crack SHA-256. Now, if that IP address had been in Poland....