- Why is it important to make sure that miners spend money (on electricity) while mining?
Miners have to obey the BTC network rules in order to get compensate by fees and puzzle resolution - Why would it be very difficult for someone to go back change a previously added block?
In order to be able to change a block you should have over 51% of the nodes processing BTC, that is impossible so far. - How does the network regulate mining difficulty?
Bitcoin’s mining difficulty is programmed to adjust itself every 2,016 blocks
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Miners have to guess the nounce, this is the proof of work and they do that because they are incentivated and have to follow the rules. Break the rules will mean spending so many money on electriticity to have your block accepted.
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Because they will have to change all the following blocks.
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It dipends on the number of miners guessing. If there are lot of them making guessing nounce, it will have to be more difficult and the as the market will be low.
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- Theoretically it secures the network and provides the security . ( some current and future developing will most likely move to green solutions in order to minimize the cost)
- Amount of power consumption and difficulty of changing the block would take a long time in current development of the network and most likely not be wort it .
- I believe its regulated by hashing power . More power more difficult it has to be and also its connected to the set time of creating the block .
More I learn more I understand mining purge and potential price manipulation of BTC between large players in this global business.
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So they are financially incentivized to play by the rules. They would lose money if they try to cheat, because their machines are still consuming energy by making calculations, but the network will not accept the work of the cheating miner.
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Because they would need to mine all the blocks that came after it as well, which takes time and energy, and the network will only accept the longest chain.
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By lowering the target of the hash when hashrate increases, so it’s more difficult to guess the nonce.
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1. Why is it important to make sure that miners spend money (on electricity) while mining?
Spending money on electricity it INCENTIVES the Miner to respect the protocol of the Blockchain in order to get paid. If the Miner doesn’t respect the protocol, the Nodes of the Blockchain will see the inappropriate behavior of the Miner which will result in “destroying” the inappropriate Block created by the Miner. Having this, the Miner will lose the money spend on electricity for creating the Block.
2. Why would it be very difficult for someone to go back change a previously added block?
If someone goes back and modifies something in the Blockchain, the whole structure will collapse from where the modification was made to present.
Theoretically it can be done, but the links of the Blocks destroyed needs to be recreated by the Miner that made the modification in order to catch up with the new ones created, which will take a very long period of time to do so.
I don’t know if this operation can be made faster with newly discovered “Quantum Computers”. - Maybe someone can answer this.
It can be resembled with Time Traveling: - If someone goes back in the past and makes the smallest modification, for example moving a tiny rock, the future will be completely altered. The same goes with the Blockchain.
3. How does the network regulate mining difficulty?
The difficulty of the network is regulated by Lowering the Target. As we know, the Difficulty is represented by the Number of Miners inside the Blockchain. The more the Miners are the Lower the Target is.
As the Target gets lower, Miners will have to spend a lot of electricity in order to find the correct HASH. For some Miners this will not be efficient any more, therefore they will abandon the Mining process since it is to expensive. As Miners leave the Blockchain, the Target Level rises.
1.The cost ensures the miners will follow the rules so they receive the incentives of Block chain Rewards and transaction fees. Thus POW
2.The difficulty of changing a block could take over 100 years. Like changing a footprint or fingerprint. All the data is altered from previous blockchain breaks the link.
3.Finding a target with a nonce. More miners higher difficulty and less miners less difficulty.
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Why is it important to make sure that miners spend money (on electricity) while mining?
It functions as an incentive to the miners to play by the rules. If a miner do anything shady than the mined block will not be accepted by the network and the miner will lose all the rewards for the work that the miner put in to create the block.
Why would it be very difficult for someone to go back change a previously added block?
If someone wants to alter a transactions of one the previous blocks than the followings points happens:
- Altering a transaction in a previous block will change the hash of block. This in turn will invalidate all the links that comes after the altered block. Thus all the blocks after the altered block will be invalidated.
- The network always accepts the longest chain thus the chain with most proof-of-work.
- To ensure that change will be accepted by the network that person/miner needs remine all the blocks that has been invalidated.
- Also it needs to remine the all the new blocks, that network has created, to get the longest chain.
- So to succeed the person/miner needs at least 51% of hash rate of the network, which is almost impossible.
How does the network regulate mining difficulty?
Mining difficulty is determined by hash power/rate of the network. The higher hash power of the network the higher the mining difficulty.
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It is important to make sure miners spend money while mining because that keeps them honest and following the rules so that they can receive incentives (block reward and transaction fees).
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It would be very difficult for someone to go back and change a previously added block because that would affect every link between blocks after that specific block, meaning you would have to re-mine every block again, from the point of change and catch up with the blocks that are being mined presently. Doing this would take millennia and an astounding amount of resources. In theory possible, but in practice impossible.
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The network regulates mining difficulty by lowering the target more and more as the difficulty increases, thus making it more difficult to guess the nonce.
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- This incentivize’s the miner to solve the problem by using electricity POW They want to recoup their money by solving the problem and guessing the nonce
- If a previous block is changed everything will change
- Mining is regulated by lowering the target when there are more miners
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The more expensive is the mining operation more secure is the network.
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He have to hash the previously block again and with him the following blocks up to the last block. But in this time the other miners mining new blocks so it will be impossible to catch up. The chain of the other miners will be also longer and the longest chain will be accepted.
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The minors have to fix a puzzle by hashing the previous block, the tx from the new block and the nonce. The result have to be lower then the target. The target is more difficult means lower with higher hash rate and more miners.
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This doesn’t matter, because every 2016 blocks, difficulty gets adjusted to preserve an average of 10 minute block time, no matter how strong and effecient your miner is
Many people are confusing the nonce and target hash.
The nonce is just a random number you need to add to a block, so when you hash the entire block (nonce included) it would produce a block hash lower than the target (meaning having a bunch of leading zeros)
If you check the bitcoin blockchain, you will see that blocks always have a hash starting with couple of leading zeros. The more zeros, the harder it was to find a nonce that produces a hash low enough
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@fabrice thank you for your answers. Means a lot and thank you for the time you take to answer.
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No problem, Happy to help out 
just tag me if you have problems understanding something in this course.
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You are a brave man to offer such help… you obviously don’t know me !! 
Every student is equal to me, and everyone deserves attention and help to understand this important technology 
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So they be incentivised to not brake the protocol. So they do not make fake transactions, double transactions etc. Because if they have to spend money and than try to cheat in the end they will lose money because the block they create with some wrong info there block will be rejected and they have just spent a lot of electricity and just lost there money.
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If they go back and change the block all the links starting from the previous block they change will be broken and then they have to remine all the blocks and catch up with the blocks the miners have added while he mines the link he broke. But the difficulty is too high to do that, it is possible but very unlikely and they would actually make more money if they just mine by the protocol instead.
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The network lowers the target of the hash the miner have to guess while hashing the previous block, his chosen transaction and his blocks hash and a nonce. So the lower the target the harder for the miner to guess a nonce that will give him the hash of all that that is actually lover than the target.
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Answer:
- Miners spend electricity to secure the network by competing for Reward.
- It should be impossible because of rules in place, and you would have to correct other blocks also which can go on and on.(so really you can’t alter the history because of mining).
- Mining difficulty is regulated by POW algorithm, math and physics
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Why is it important to make sure that miners spend money (on electricity) while mining?
By spending money on electricity, miners will have skin in the game and therefore incentivise them to follow the rules and earn a block award & transaction fee. -
Why would it be very difficult for someone to go back change a previously added block?
Because it would invalidate all the blocks following it and you would need to re-mine them again. From what I can gather, this would be a monumental pain in the arse. -
How does the network regulate mining difficulty?
If there is an increased number of miners in the network, the target will be set lower which leads to greater difficulty to solve the puzzle.
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- Because that’s that way they are motivated to follow the rules in order to get back their investment and make profit.
- Because they have to mine all the block that follow the block they’ve changed and that take a lot of hashing power and time.
- If the mining difficulty is high that means there are a lot of miners and the target is set lower, which makes mining harder, if there are less miners, difficulty is low and target is set higher which makes minning easier.
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