Bitcoin Forum

Does that mean that no block has been mined in 45 minutes? Why would that be  ???

Screenshot from blockchain.info from today 19:38 UTC

https://i.imgur.com/QrpRz3A.png

That's normal. There isn't anything happening. It is just the normal variance and randomness inherent with BItcoin mining.

And since then, there have now been 4 more blocks mined in the past 20 minutes (and all within 4 minutes of each other):

https://i.imgur.com/TZT1rpq.png

That's the thing about random processes.  They tend to be random.  However, the conditions can be set up to that the long term average is within a certain range.

For example, if I roll a perfectly balanced 6-sided die three times, it is entirely possible and reasonable for me to get a 2 all three times in a row.

However, if I roll that same die 6,000 times, it would be extremely unlikely that I would get a 2 all 6,000 times.  On average, I would only get a 2 one thousand times (give or take a bit due to randomness not being an exactly predictable thing).

Thanks for Your answers. Could not imagine such a variance in the hashing time. So one should always calculate at least 60 mins for first confirmation of a transaction. No high transaction fee helps against that randomness. I find this unpredictability a little bit disturbing and sad.

Does the block finding time depends on the number of transactions?
What happens if one day not enough transactions occur? even if hash power is the same.

 Read something - https://en.bitcoin.it/wiki/Block

Block finding time depends only on difficulty - https://en.bitcoin.it/wiki/Difficulty

The blocks continue to get solved regardless of the number of transactions on the network.

I really should know better than to waste time answering someone with a sig ad.

However, since this assumption seems to come up pretty often even among those that are not participating in a sig ad campaign...


No.  It takes effectively the same amount of time to mine a block with 1 transaction as it does to mine a block with 5000 transactions.  When mining, you are only hashing the 80 byte block header.  The size of that header doesn't change, regardless of the number of transactions.


Blocks with 0 transactions get mined all the time. Transactions are not needed for mining.  Transactions do not change the time it takes to mine a block.

That kind of wait for the next block is normal but can be very frustrating if you've paid a high fee hoping to get your transaction confirmed quickly in the next block.

It's happened to & annoyed me several times.

It means that network's hashing power is not very stable. In average new block should appear every 10 minutes. Bitcoin network recalculates difficulty every two weeks, so such fluctuations can happen. In some new cryptocurrencies difficulty recalculated more frequently, so such fluctuations is rare.

It is true the hasing power fluctuates over time. The higher the total hashrate, the higher the difficulty. It is also true the difficulty is re-calculated every ~two weeks.

However, in the fictive network of democoin (a clone of bitcoin with the same specs) there is only one miner that hashes at 2 Th/s 24 hours a day, 7 days a week. The total hashrate stays exactly the same, the diff doesn't change at all. Still, the time between blocks is not the same. The average time between two blocks will be ~10 minutes, but things like 40 minutes between blocks can still happen, even in this demo network.
It's all about odds and averages. An asic producing 2 Th/s actually means that the asic is a device that generates 2000000000000 hashes every second. There is no guarantee that after exactly 10 * 60 * 2000000000000 hashes, the "correct hash" is calculated.

It does NOT mean that.  Hashing power is quite stable over this time frame and does not cause this type of variation between block times over this time period.

You can read more about the distribution of block times in this thread among many other discussions all over the web:
https://bitcointalk.org/index.php?topic=192695.msg2009649#msg2009649

No, difficulty adjusts after 2016 blocks.

Not that unusual. I once had to wait two hours for a block, and by the time the block was mined, there was a huge backlog of transactions in the mempool that I had to wait three more blocks to get confirmed.

Hm, again since 33 min no block mined :( This possible random lag of transaction confirmation should be mentioned more often, especially for newbies.

https://i.imgur.com/x3SCZBn.png

It's been mentioned, asked, and answered often enough. You're just whining.

10 minutes is the average.

Perhaps this web page will help you understand:
https://en.wikipedia.org/wiki/Average

Since the majority of blocks are faster than 10 minutes, the only way you can have an average of 10 minutes per block is if some of the blocks are significantly slower than 10 minutes. That's the way averages work.

If I want an average of 10, over a set of 10 items and I have:

• 8
• 2
• 6
• 2
• 3
• 1

Then at least one of the remaining 4 items will HAVE to be larger than 12.


If I have:

• 4
• 2
• 5
• 2
• 3
• 1
• 6

Then at least one of the remaining 3 items will HAVE to be larger than 16.

As you can see, the more values you have less than the target, the larger the few remaining numbers will be.

The time between blocks is actually completely random, and there is nothing enforcing any specific time for any specific block.

Think about rolling a six sided die.
On average over the long term, you will roll each digit about 1/6 of the time.

However, there is nothing enforcing that any specific roll will be any particular value.  It is entirely possible to roll a 6 five times in a row.

Similarly, with bitcoin blocks, the long term average is 10 minutes per block, but it is entirely possible to have several blocks within a few seconds of each other, or some blocks that take as much as an hour.  The longer the time between blocks the lower the probability that it will happen.  Shorter times have a much higher probability and therefore are FAR more frequent.