The nonce is just a number miners use to help them find a hash output that is below the target, not the nonce itself. 
1 Like
not sure how you would write computer language to verify smoke signals, but it definitely fires the imagination!
1 Like
Bitcoin is Currency, Protocol, Language.
So how many transactions āfitā in a block? Because the miner has to decide how many transactions he puts into the block before he starts mining for the nonce, right? So how does he decide how many he puts into the block?
My other question is: As a new block is only created every 10 Minutes, does that mean if I send out a transaction, right after the last block was mined, it would take exactly 10 minutes for my transaction to be confirmed (given my fee is high enough)?
Thanks for your answers!
The block is limited to 1MB, how much txs fit on a block depends on their complexity. Tbh I never did any approximations how many txs fit in a block on average.
A new block is found approximately every 10 minutes. This is regulated based on the network hash rate. There is no guarantee that the block will be fin in exactly 10 minutes, maybe new miners came and will be faster, maybe a lot of them dropped out, maybe a miner got lucky and found the right hash under a minute or the network is not lucky and takes 15 minutes. There is not way if telling for sure.
2 Likes
Thanks for your answer!
1 Like
If the Blockchain is continuously growing and increasing in size, how is this sustainable long term? Will the size of the blockchain grow faster than the technology keeping it running?
1 Like
Thank you!! I canāt wait to check it out.
1 Like
I have two questions:
-Is a 100% sure that your transaction will at some point confirmed in a block no matter how low your fee can be?
-Does anyone know what is the largest time (average) that a BTC transaction can be confirmed?
I donāt see this as a problem, modern HDDs can be the size of up to 20TB which can hold 100s of years of blockchain data given the fact that today Bitcoin blockchain is about 500GB after 10+ years.
By the time the size will grow larger than that Iām quite sure new technologies will exist that will be able to store the entire blockchain for years to come.
Not really, most nodes have a config that can set the size of the mempool and drop old or cheap txs. By default I think its 300MB and up to 14 days, but it can be changed. But in general if the mempool exceeds 300MB it will start dropping cheaper txs or if a tx is older than 14 days and has not beenn confirmed.
It depends on the fee. I have recently received a tx from a friend with 5 sat/B it took about 2 days to confirm and cost 0.0000084 BTC about 25 cents 
https://blockstream.info/tx/29e4b4a7d035b8d53187ffc5597b6755b3af6e9aac2e7f5d7086159898508a37
4 Likes
Thanks Jon, this was an invaluable add-on for better understanding how Blockchain & Public / Private Key Pair Message Signing work in practice
1 Like
Wow really helpful answers, thanks man!
Hi! The point about SMS got me thinkingā¦ Iām a complete noob here, but Iād like to develop a blockchain app for use in retail outlets, with data being sent to/from customers phones when theyāre in-store. One of the issues in retail, is that their internet access is often desperately unreliable! Iām sure Iāll figure this out towards the end of these courses, but is a blockchain app viable if internet access is unreliable (and the bitcoin network only intermittently available)? Or should I just give up on the ideaā¦?
A blockchain app will not help you solve the issue with connectivity. If they want a reliable internet connection then they should invest in a wifi network 
A wallet though doesnāt require a stable connection, it will sync once it gets a connection to another node.
Ah, thanks for taking the time to reply! I canāt control what retailers do; I was really just wondering what could be done, in the messy real-world they live in. Your point about wallets reassured me though, thanks. The āappā Iām thinking about isnāt (yet) a lost cause
Ok, great information.
Hello everyone!
I am stuck at one question
How could you use the notion of transaction inputs and outputs to increase privacy in your tx?
It is probably very simple but I would really appreciate if someone could explain this to me 
1 Like
The most basic method you can use is to not reuse addresses and create a new address every time you receive funds or send change back to yourself.
When sending change back to yourself to a new address, there is no way of knowing which tx output was used to pay a service and what went back to the sender (50:50 chance).
3 Likes
Hi @Alko89,
Thank you for clarification, that does make sense! What I donāt understand is, if I send a certain amount I donāt actively send me change back. Does this happen automatically? If it happens automatically how do I send it to another address?