summary of Proof of Work

[nc50lc]

Or does the "Longest chain" refer to mined blocks that become orphaned?

Bcash is another coin, no matter how long that chain is. It has nothing to do with bitcoin.

Yup, the "orphaned blocks" creates a "mini-blockchain" which are "short" because almost all of the nodes are invalidating it and after the remaining ones that validates the transactions in those blocks (considered as running a new coin's blockchain: a hard fork) stopped, that new/incidental/accidental "hard fork's" blockchain has ended which makes it "shorter" than the valid chain.

BitcoinCash and other "Planned Hard Forks" however, got a considerably high amount of nodes to continue their own blockchain.
And as bitmover said, it is now a different coin in a different blockchain.

<edit: fixed quoted msg>

[bob123]

Sorry if this is a very dumb question, but can you help me understand the "longest chain" is the valid chain concept?

The longest valid chain is the actual blockchain.

This is something I'm confused about when it comes to bcash, as it is currently the longer chain. Is it because these are two separate coins at this point?

Bcash does follow different consenus rules. They hardforked to a bigger block size.
The bcash chain is longer because the difficulty is (and was) way lower while some miner were starting to mine on the bcash chain.
Bcash blocks are not valid for the bitcoin chain.

 

Or does the "Longest chain" refer to mined blocks that become orphaned?

No, longest valid (meeting all consens rules) chain.

Or does the "Longest chain" refer to mined blocks that become orphaned?

Yup...

No. https://bitcoin.stackexchange.com/questions/5859/what-are-orphaned-and-stale-blocks

[BEX]

Yes and Proof of Stake (and Delegated POS) might be a solution to POW, hense Ethereum current move to POS...https://www.blockchains-expert.com/en/proof-of-work-vs-proof-of-stake-2/

[bitmover]

Yes and Proof of Stake (and Delegated POS) might be a solution to POW, hense Ethereum current move to POS...https://www.blockchains-expert.com/en/proof-of-work-vs-proof-of-stake-2/

Nobody knows when ethereum Casper (pos) will be released. And Casper is not 100% proof of stake, as most blocks will still be pow in the beginning.

I see many people saying"a solution to pow" as if pow was a problem and pos was a solution to every problem. Pls still needs to be tested in a great scale blockchain like ethereum. Until then we don't know what to really expect.

[DevilOper]

You can calcule the probability for a miner to reverse a transaction here: people.xiph.org/~greg/attack_success.html

Got it, thank you! However, when I check the tool, with 40% hash-power a group can have more than 50% probability to win over the network. It is not really needed to have enough 51% I guess.

I can easily assert the calculation is totally wrong: for one single confirmation the probability to reverse a transaction literally means the probability to 'mine' a block -> is equial to the 'Proportion of hash-power'.
Then try to enter the 'Proportion of hash-power' = 0.5 and the 'Number of confirms' = 1.

[bob123]

I see many people saying"a solution to pow" as if pow was a problem and pos was a solution to every problem.

The actual problem with PoW is the used energy.
With the rising average temperature and the media comparing BTC's energy usage to countries like denmark, a 'solution' would be handy.

Wether PoS can (safely and securely) replace PoW is neither proved nor disproved.
It may but also may not be the 'solution'.

But if the hashrate (with more miner) and the energy consumption is going to rise further, governments will start cracking down on mining (like already happened in several countries).

[bitmover]

I see many people saying"a solution to pow" as if pow was a problem and pos was a solution to every problem.

The actual problem with PoW is the used energy.
With the rising average temperature and the media comparing BTC's energy usage to countries like denmark, a 'solution' would be handy.

Wether PoS can (safely and securely) replace PoW is neither proved nor disproved.
It may but also may not be the 'solution'.

But if the hashrate (with more miner) and the energy consumption is going to rise further, governments will start cracking down on mining (like already happened in several countries).

I think this is hypocrisy, as Christmas lights consume as much energy.
http://www.coindaily.co/2017/12/14/christmas-decorations-consume-as-much-electricity-as-bitcoin-mining/

And how much energy does the whole banking system consumes?
Hi much does visa consumes? Nobody knows exactly, while btc mining is easy to point out , as someone who does not understand what bitcoin is mining is just a waste of energy to create some nerd money in a computer.

[bob123]

I think this is hypocrisy, as Christmas lights consume as much energy.
http://www.coindaily.co/2017/12/14/christmas-decorations-consume-as-much-electricity-as-bitcoin-mining/

While you - and any other reader of coindaily.co - know this fact, the majority of people (regardless wether invested in BTC or never heard from BTC before) will hear the comparison between BTC and country X.
People still tend to accept christmas lightning (because hey, its christmas) over a mathematically (and technically) proven working form of a decentralised ledger without any influence of a 3rd party.

And how much energy does the whole banking system consumes?
Hi much does visa consumes? Nobody knows exactly, while btc mining is easy to point out , as someone who does not understand what bitcoin is mining is just a waste of energy to create some nerd money in a computer.

If you consider all the energy used in the banking system (not just server uptime) i would assume that its definetely more than the energy consumption of the BTC network (just a personal guess tho).
But nobody cares what visa consumes. Visa is a ('necessary') working financial instrument. You won't find the media talking about the enormous effort needed to keep the visa network alive.

This is (sadly) the point.

[bitmover]

I think this is hypocrisy, as Christmas lights consume as much energy.
http://www.coindaily.co/2017/12/14/christmas-decorations-consume-as-much-electricity-as-bitcoin-mining/

While you - and any other reader of coindaily.co - know this fact, the majority of people (regardless wether invested in BTC or never heard from BTC before) will hear the comparison between BTC and country X.
People still tend to accept christmas lightning (because hey, its christmas) over a mathematically (and technically) proven working form of a decentralised ledger without any influence of a 3rd party.

And how much energy does the whole banking system consumes?
Hi much does visa consumes? Nobody knows exactly, while btc mining is easy to point out , as someone who does not understand what bitcoin is mining is just a waste of energy to create some nerd money in a computer.

If you consider all the energy used in the banking system (not just server uptime) i would assume that its definetely more than the energy consumption of the BTC network (just a personal guess tho).
But nobody cares what visa consumes. Visa is a ('necessary') working financial instrument. You won't find the media talking about the enormous effort needed to keep the visa network alive.

This is (sadly) the point.

Well, in my opinion proof of work is not the problem then.
He problem is all that misinformation about it and about bitcoin, in a attempt to discredit it to common people, who "cares about global warming", favoring banks and Visa.

I think even that proof of work can sponsor renewable energy sources, like solar panels. Any excess energy produced by them can be directed to bitcoin mining, that would make the capital recovery make much faster

[DevilOper]

I suggest you to compare not the overall energy consumption but one per transaction, since the transactions are not the only thing banking system does, and VISA performs much more transactions per day than bitcoin in a year.

[BanishedDemon]

VISA performs much more transactions per day than bitcoin in a year.

Agree , it is worth searching at estimates for a consistent with-transaction power cost because we will examine that price to existing fee structures. it's also a extra tangible way to represent price-for-electricity. simply understanding that total bitcoin mining consumes x quantity of electricity is thrilling, but it's better to discuss how many transactions we're definitely getting for all that power spent.

[bitmover]

Edit:

Fixed images, which were not showing up anymore

[Aura]

This puzzle consists in scanning for a value (called Nonce) that when hashed, the hash begins with a number of zeros.

From this line it seems that the only hash input is the nonce. However, from my understanding, all block data is hashed. The only variable in this block of data is the nonce, therefore it can change the hash output.

The difficult in finding that nonce increases exponentially as more zeros are required by the block. Difficult is adjusted so that one block is mined every 10 minutes.

This sentence would be more clear if you would introduce the frequent term difficulty. Optionally, you can add that the difficulty only changes every 2016 blocks or average two weeks.

Despite this, I still find your summary very informative and accurate.

[bitmover]

This puzzle consists in scanning for a value (called Nonce) that when hashed, the hash begins with a number of zeros.

From this line it seems that the only hash input is the nonce. However, from my understanding, all block data is hashed. The only variable in this block of data is the nonce, therefore it can change the hash output.

The difficult in finding that nonce increases exponentially as more zeros are required by the block. Difficult is adjusted so that one block is mined every 10 minutes.

This sentence would be more clear if you would introduce the frequent term difficulty. Optionally, you can add that the difficulty only changes every 2016 blocks or average two weeks.

Despite this, I still find your summary very informative and accurate.

Thanks, just added your suggestions

There are far too many details, and I try to keep this as simple as possible

[Aura]

This puzzle consists in scanning for a value (called Nonce) that when hashed, the hash begins with a number of zeros.

From this line it seems that the only hash input is the nonce. However, from my understanding, all block data is hashed. The only variable in this block of data is the nonce, therefore it can change the hash output.

The difficult in finding that nonce increases exponentially as more zeros are required by the block. Difficult is adjusted so that one block is mined every 10 minutes.

This sentence would be more clear if you would introduce the frequent term difficulty. Optionally, you can add that the difficulty only changes every 2016 blocks or average two weeks.

Despite this, I still find your summary very informative and accurate.

Thanks, just added your suggestions

There are far too many details, and I try to keep this as simple as possible

I understand your decision.
Keep up the good work!

[bitmover]

I have just moved this topic to beginners and help board. I believe it will fit better here.
I created this when I was reading mastering bitcoin book and learning a lot about BTC 

Hope it can help newbies

[bitmover]

This topic is also available in Portuguese (short version) and Arabic (by Zwei), recently translated.

[bitmover]

Friendly hump

Hood read for new comers who want to learn about bitcoin and how it works, why it expands energy and so on.