Why Bitcoin blocks are generated every 10 minutes?

[walerikus]

I have asked this question to myself many times. Today I finally realized why.
I just wonder what people think about it.

I strongly believe everything Satoshi did in bitcoin protocol code and whitepaper, he did for a reason.
Satoshi spent around 2 years on designing the architecture of the network, everything he was explaining was meaningful.
For protocol is set in stone he was referring the core design which is described in whitepaper.

So, I am curious of what people think about 10 minutes block time.

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[ranochigo]

It's a rather controversial topic to discuss about. The thing about block interval is that the security of the network is taken into consideration. With a faster block, there is a risk that the propagation of the block within the network is too slow and that miners ends up mining a lot of orphans and causing more forks. Since Satoshi never publicly stated his rationale for the 10 minute block interval, it is widely assumed to be arbitary. Arguably, with better internet connection right now, the block interval can be lowered but there are still quite a few concerns.

[DaCryptoRaccoon]

You are correct in saying that  it is noted in the original paper but only as a reference.

A block header with no transactions would be about 80 bytes. If we suppose blocks are generated every 10 minutes, 80 bytes * 6 * 24 * 365 = 4.2MB per year. With computer systems typically selling with 2GB of RAM as of 2008, and Moore’s Law predicting current growth of 1.2GB per year, storage should not be a problem even if the block headers must be kept in memory.

In my view it was done as a way to limit the amount of wastage as the block time increases you would see wastage drop there could also be a number of other factors that could point to why the 10 min time was included.

Such as if many nodes were to be generating the same block at the same time it could lead to more frequent forks this in turn would lower the strength of the network and push the times for conformations up.

For example if everyone is to be mining block 999,999 and miner A solves the block first and pushes it to the network all the other miners who would be at { t0 + t } t= time taken by miner A to mine and submit block 999,999.

Lets say miner B finds miner A's block at {(t0 + t)+ 1} with taking into account network latency miner B and all other miners who finish mining the same block where (t0 + t)< (t0 +t) + (delta_t)i < (t0 + t) + 1

All are successful in mining but they would have wasted there energy in doing so this shows the total wastage of the network resulting in a orphan block would need to be.

sum of { (t+ (delta_t)i ) * (hr)i } for every i

I'm sure there are other reason behind this that I have missed out on but it is an interesting topic to look over even just as a thought experiment.

[walerikus]

It's a rather controversial topic to discuss about. The thing about block interval is that the security of the network is taken into consideration. With a faster block, there is a risk that the propagation of the block within the network is too slow and that miners ends up mining a lot of orphans and causing more forks. Since Satoshi never publicly stated his rationale for the 10 minute block interval, it is widely assumed to be arbitary. Arguably, with better internet connection right now, the block interval can be lowered but there are still quite a few concerns.

No, the network won't be less secure with 5 minute block time. I don't really think so, for example Digibyte has 15 second block time, but it is very secure, proof of work, I have never heard it was hacked, 51 attacked, reversed or forked. The point is not solely the security in my opinion.

You are correct in saying that  it is noted in the original paper but only as a reference.

A block header with no transactions would be about 80 bytes. If we suppose blocks are generated every 10 minutes, 80 bytes * 6 * 24 * 365 = 4.2MB per year. With computer systems typically selling with 2GB of RAM as of 2008, and Moore’s Law predicting current growth of 1.2GB per year, storage should not be a problem even if the block headers must be kept in memory.

In my view it was done as a way to limit the amount of wastage as the block time increases you would see wastage drop there could also be a number of other factors that could point to why the 10 min time was included.

Such as if many nodes were to be generating the same block at the same time it could lead to more frequent forks this in turn would lower the strength of the network and push the times for conformations up.

For example if everyone is to be mining block 999,999 and miner A solves the block first and pushes it to the network all the other miners who would be at { t0 + t } t= time taken by miner A to mine and submit block 999,999.

Lets say miner B finds miner A's block at {(t0 + t)+ 1} with taking into account network latency miner B and all other miners who finish mining the same block where (t0 + t)< (t0 +t) + (delta_t)i < (t0 + t) + 1

All are successful in mining but they would have wasted there energy in doing so this shows the total wastage of the network resulting in a orphan block would need to be.

sum of { (t+ (delta_t)i ) * (hr)i } for every i

I'm sure there are other reason behind this that I have missed out on but it is an interesting topic to look over even just as a thought experiment.

In my opinion it has to do with simplified verification system, no matter how big will the block size be, the quote you refer

A block header with no transactions would be about 80 bytes. If we suppose blocks are generated every 10 minutes, 80 bytes * 6 * 24 * 365 = 4.2MB per year. With computer systems typically selling with 2GB of RAM as of 2008, and Moore’s Law predicting current growth of 1.2GB per year, storage should not be a problem even if the block headers must be kept in memory.

Is the answer for the 10 minutes block time. You can have a light node with 4.2MB per year storage. There are some other blockchains that have much smaller block time but still are successful in security, Digibyte for example.

[ranochigo]

No, the network won't be less secure with 5 minute block time. I don't really think so, for example Digibyte has 15 second block time, but it is very secure, proof of work, I have never heard it was hacked, 51 attacked, reversed or forked. The point is not solely the security in my opinion.

51% attack is not about the block time. As long as you have 51% of the total hashing power, the attack can be executed.

If you observe, exchanges mostly requires those coins with a faster block interval to have a higher confirmation than those who don't. Reason being, forks are more prone to occurring with faster block times than a coin with a slower one.

[Kakmakr]

This also looks like a good answer :

    " Ten minutes was specifically chosen by Satoshi as a tradeoff between first confirmation time and the amount of work wasted due to chain splits. After a block is mined, it takes time for other miners to find out about it, and until then they are actually competing against the new block instead of adding to it. If someone mines another new block based on the old block chain, the network can only accept one of the two, and all the work that went into the other block gets wasted. For example, if it takes miners 1 minute on average to learn about new blocks, and new blocks come every 10 minutes, then the overall network is wasting about 10% of its work. Lengthening the time between blocks reduces this waste.

    As a thought experiment, what if the Bitcoin network grew to include Mars? From the farthest points in their orbits, it takes about 20 minutes for a signal to travel from Earth to Mars. With only 10 minutes between new blocks, miners on Mars would always be 2 blocks behind the miners on Earth. It would be almost impossible for them to contribute to the block chain. If we wanted collaborate with those kinds of delays, we would need at least a few hours between new blocks. "

Source : https://bitcoin.stackexchange.com/questions/1863/why-was-the-target-block-time-chosen-to-be-10-minutes

I wonder if Satoshi envisioned that Bitcoin might go inter-planetary and that you might need enough time for new blocks to be mined, to make up for the speed it would take for the signals to reach earth from other planets.    He might even have known that some internet connections are way slower than others and that you need a good delay for everything to synchronize properly.  

We know miners in China complained about the firewalls influencing their internet speed, so bandwidth speed is definitely a problem.  

Another point of view is the following :

" The average block time of the network is evaluated after n number of blocks, and if it is greater than the expected block time, then the difficulty level of the proof of work algorithm will be reduced, and if it is less than the expected block time then the difficulty level will be increased. " - Source : https://medium.facilelogin.com/the-mystery-behind-block-time-63351e35603a

[figmentofmyass]

Moving BTC to a 5 minute blockspeed would literally double it's transaction capacity.

orphaning rates aside, this is contentious for another reason: it speeds up the emission rate by a factor of 2. those aren't the monetary properties that bitcoiners signed up for.

it would also only represent a small, linear increase in throughput capacity. what we need are mechanisms that can provide exponential increases. LN is one such mechanism.

[alani123]

Come to think about it, if you see the difficulty re-target time, it's every two weeks approximately. And that's only because it comes every 2016 blocks, which is a number that if you multiply by 20 (2 weeks, 10 minutes) you get the minutes in a week.

And, on the other hand, block halvings happen almost around every four years. That would be ever 210000 to be precise. Or approximately 2100000 minutes. 2100000 divided by the minute in a year (525600) equals 3.99543378995. This is equivalent time to 126000000 seconds.

I don't know the significance of 126000000, if any, but the 10 minute block time target might have just been part of an attempt to have round numbers in seconds. In programming (don't take my word for it) seconds matter more than minutes or any other time measurement. See for example how how times is calculated with the UNIX system. It's all based on seconds. It's easier to keep track of accurately and derive minutes, hours, days and years from it other than the opposite.

[o_e_l_e_o]

I wonder if Satoshi envisioned that Bitcoin might go inter-planetary and that you might need enough time for new blocks to be mined, to make up for the speed it would take for the signals to reach earth from other planets.

Not a problem with Lightning. Users in communities who are far behind the main network for whatever reason only have to experience that delay once to open a channel to their local neighbors. Once done so, the community can all transact with each other endlessly, and only need to factor in the delay whenever they want to add or withdraw funds from their individual holdings.


The 10 minute block time was also mentioned by Satoshi in a few of his emails. See the following for example (emphasis mine): https://satoshi.nakamotoinstitute.org/emails/cryptography/threads/1/#014849

They use a proof-of-work chain to solve the problem. Once each general receives whatever attack time he hears first, he sets his computer to solve an extremely difficult proof-of-work problem that includes the attack time in its hash. The proof-of-work is so difficult, it's expected to take 10 minutes of them all working at once before one of them finds a solution. Once one of the generals finds a proof-of-work, he broadcasts it to the network, and everyone changes their current proof-of-work computation to include that proof-of-work in the hash they're working on. If anyone was working on a different attack time, they switch to this one, because its proof-of-work chain is now longer.

From the bold sentence, could it be suggested that the 10 minute block time was initially chosen as a function of the minimum difficulty (32 zero bits, which is 8 leading zeros) and the hashing power available to Satoshi at the time?

[ABCbits]

Moving BTC to a 5 minute blockspeed would literally double it's transaction capacity.

orphaning rates aside, this is contentious for another reason: it speeds up the emission rate by a factor of 2. those aren't the monetary properties that bitcoiners signed up for.

it would also only represent a small, linear increase in throughput capacity. what we need are mechanisms that can provide exponential increases. LN is one such mechanism.

Alternatively you could reduce block reward 50% to keep emission rate. But both changing block time interval or block reward require hard-fork, which won't be approved, especially because Bitcoin community prioritize backward compatibility.

[vjudeu]

Max supply: 21,474,836.47 coins (int32 max)
Block time: 512 seconds (2^9)
Blocks per halving: 262,144 (2^18)
First block reward: 40.96 coins (2^12)

It is possible that initially such numbers were binary-based. Later, they were probably converted into decimal-based numbers. It is also possible than when after 12 halvings the block reward was 0.01 coin per block, it was later granted every 2, every 4, ..., finally every 262,144 blocks and then drops to zero. That is probably how the name was chosen: bit-coin, the coin based on bits. Of course humans seems to be more comfortable with decimal numbers and since it does not really matter if these numbers are round binary or round decimal numbers, Satoshi chose decimal to encourage more people to use this coin.

[HeRetiK]

The block interval of 10 minutes was probably simply a very conservative guesstimate.

Keep in mind Bitcoin was pioneering the field, it then took the first generation of alts to tinker with the basic parameters to see what works and what doesn't. Turns out Litecoin's block interval of 2.5 minutes works just as fine. Some alts reduced their block interval into the tens of seconds or even less with... not so good results. Orphan rate becomes a real problem at that time scale and needs to be dealt with (e.g. Ethereum paying subsidy for uncle blocks), otherwise your coin will be quickly forgotten.

Also you gotta think ahead a bit -- between Earth and Mars you have a data roundtrip time of 6 to 9 minutes!

Moving BTC to a 5 minute blockspeed would literally double it's transaction capacity.

That's just a sneaky way to increase blocksize

[Wind_FURY]

It's a rather controversial topic to discuss about. The thing about block interval is that the security of the network is taken into consideration. With a faster block, there is a risk that the propagation of the block within the network is too slow and that miners ends up mining a lot of orphans and causing more forks. Since Satoshi never publicly stated his rationale for the 10 minute block interval, it is widely assumed to be arbitary. Arguably, with better internet connection right now, the block interval can be lowered but there are still quite a few concerns.

But looking at Bitcoin as it is running today, I believe there was some effort made by Satoshi on how the network might be before writing the first line of code.

The block interval of 10 minutes was probably simply a very conservative guesstimate.

Keep in mind Bitcoin was pioneering the field, it then took the first generation of alts to tinker with the basic parameters to see what works and what doesn't. Turns out Litecoin's block interval of 2.5 minutes works just as fine. Some alts reduced their block interval into the tens of seconds or even less with... not so good results. Orphan rate becomes a real problem at that time scale and needs to be dealt with (e.g. Ethereum paying subsidy for uncle blocks), otherwise your coin will be quickly forgotten.

Also you gotta think ahead a bit -- between Earth and Mars you have a data roundtrip time of 6 to 9 minutes!

Moving BTC to a 5 minute blockspeed would literally double it's transaction capacity.

That's just a sneaky way to increase blocksize

Ignore him. He's a troll, and he's clearly a big blocker troll.

[AdolfinWolf]

More transactions capacity means lower fees for the users and more potential profit for the miners.
Maybe the dummy should explain why he want the miners to go broke and the users to be unable to afford onchain transactions.  

Yet, those that pretend they care about bitcoin want to keep it crippled onchain compared to all other coins.  
This should make you wonder, who actually cares about bitcoin survival and who just pretends they do.  

Blockchain sizes will grow for one, causing bitcoin to become even more centralized.

And, once you start increasing block sizes, where are you going to stop? 8 mb? 16 mb? 32 mb?

There's no limit to which you can go in that case, which doesn't sound like a long term solution to me...But.. What do i know.

[ABCbits]

There's no limit to which you can go in that case, which doesn't sound like a long term solution to me...But.. What do i know.

You can use hardware/internet growth when deciding block size increase, BIP 103 (https://github.com/bitcoin/bips/blob/master/bip-0103.mediawiki) mention such scenario.
But this idea bring many question/problem with no universal correct answer/solution :
1. What hardware should be used as reference? Raspberry Pi? Newest Intel/AMD processor?
2. Upper limit of the hardware costs used as reference
3. Should we use slowest/average internet growth as reference
4. What if block size growth is too big to the point HDD I/O speed can't keep up and SSD the only option, which makes storage costs growing quickly (e.g. Ethereum blockchain size which is about 3.8TB and grow about 1.6TB in last year)

[DooMAD]

Sad day when bitcoin community is too scared to even come near litecoin transactions performance, let alone exceed it.

Transactions avg. per hour      892
Blockchain Size    28.76 GB

Transactions avg. per hour      13,675
Blockchain Size     308.57 GB

What performance is that, then?  You seem to be once again comparing apples with celestial bodies.  Bitcoin's blockchain already grows faster in size than Litecoin's and you think users will be willing to increase the speed at which it potentially grows by a factor of 4?

[Wind_FURY]

Sad day when bitcoin community is too scared to even come near litecoin transactions performance, let alone exceed it.

Transactions avg. per hour      892
Blockchain Size    28.76 GB

Transactions avg. per hour      13,675
Blockchain Size     308.57 GB

What performance is that, then?  You seem to be once again comparing apples with celestial bodies.  Bitcoin's blockchain already grows faster in size than Litecoin's and you think users will be willing to increase the speed at which it potentially grows by a factor of 4?

The troll. Haha.

Bitcoin is about settlment assurances, not speed of transactions. Bitcoin produces more security in hashes per block, than any other shitcoin can.

[Wind_FURY]

The troll would say something, it's always off-topic, but in reality he didn't consider that the Bitcoin network is paying the miners MORE than any shitcoin out there, and therefore its miners produce more security than his 2.5-minute per block shitcoin blockchain.

An attack on a per-10-minute Bitcoin block, would cost more than 4 2.5-minute shitcoin blocks.

[Dabs]

Bitcoin will probably get left behind, as the dominant crypto with the highest marketcap precisely for all the reasons that has been stated. Even LTC has LN and SegWit. They are preparing for it.

LN will most likely be used for plenty of things that requires faster than 10 minute confirmations on chain in the blocks but can be assured that payments are accepted.

Anything else bigger (which arbitrarily changes) would still be transacted on chain and some people will be willing to wait 10 minutes or more for a confirmation anyway.

My personal estimate is within the range of $100 to $1000 USD is the threshold point for this. Some will go lower, some will go higher.

As for the block times and anything involving other planets in our solar system, there is this issue which has been called the "Center of Hash"... and strongly implies 10 minutes is good for our planet and maybe the moon, but not much anywhere else beyond 1 minute at the speed of light. So anything beyond 11 million miles from Earth, isn't going to be a good for mining, but can still relay and broadcast transactions.

This implies that other planets will have their own native blockchain currencies other than Bitcoin.

From the Sun to Mercury is more than three minutes at the speed of light ... then another two minutes to Venus ... then Earth another two minutes later. From the Sun all the way to Jupiter is about 45 minutes at the speed of light, at a distance of at least 770 million kilometers. Then another 35 minutes just to get to Saturn.

Neptune is about 4.2 hours away from the Sun. So would we have a SolarSystemCoin that has block times of several hours? 5? 6? Need to consider round trip times and other network latency effects or delays, so maybe 8 or 9 hour blocks? Would we even have coins that uses blocks at all or something else. 10 hours covers until Neptune, if we have anything on Pluto, they still can't mine. (or stake).

I think 10 minutes will work fine for the foreseeable future for transactions and miners on our planet. 2.5 minutes, 1 minute or 60 seconds, and even shorter block times may work, but I guess let's wait and see how other alts

[achow101]

Sad to see another topic get derailed into another block size and LN argument. /locked