Homework on Mining and Proof of Work - Questions

Blockchain and Bitcoin 101
#405
  1. Why is it important to make sure that miners spend money (on electricity) while mining?

Miners make an upfront investment in the network by paying for electricity. This investment incentivizes them to follow the network mining rules, or risk losing (wasting) their investment efforts.

  1. Why would it be very difficult for someone to go back change a previously added block?

It would take thousands of years to go back and re-mine all of the blocks proceeding the block you change because the current block hash will change based on the previous block hash and you would need to re-mine each proceeding block. This can take thousands of moons to complete this process. This would be a very costly process, and wouldn’t be productive since the network always chooses the longest chain of blocks.

  1. How does the network regulate mining difficulty?

The more miners there are, the higher the hash rate, and the more difficult the cryptographic puzzle. Less hash power, the puzzle is less complex (Nonce and target).

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#406

  1. They spend money on electricity to mine a block in order to solve a cryptographic puzzle.

  2. Every previous block that is changed will change every subsequent block all the while new blocks are created which means that the difficulty increases exponentially and it takes an exponential amount of time and hash power to single handedly catch back up to the current block.

  3. The target to solve the puzzle is lower when there are a lot of miners which makes the difficulty higher.

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#407

[quote=“SDoyle, post:405, topic:8439”]

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    Proof of Work protocol
  2. Why would it be very difficult for someone to go back change a previously added block?
    Because they would not only have to change that previous block, but they’d have to change every subsequent block, which is mathematically infeasible. Meanwhile, miners continue to add on to the long chain.
  3. How does the network regulate mining difficulty?
    Through hash rate. The higher the hash rate, the higher the difficulty, and vice versa.
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#408

  1. Structured incentives for them to follow the rules or they lose money which promotes honesty.

  2. because it will change everything and break the special link which you have to start all over again which would be next to impossible to succeed.

  3. It regulates lates the minor with rules written in the blockchain code to follow or they lose money. It regulates regularly so that each block is mined approximately every 10 minutes.

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#409

Miners need to spend money to incentivise them to be truthful and guess the nonce and then get their rewards

It would be difficult as links would be broken and hashes changed and rewards lost.

The more miners the lower the number and more difficult to guess the nonce.

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#410

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    To incentivize them to follow the rules of the network.

  2. Why would it be very difficult for someone to go back change a previously added block?
    Because it would need to remine all the blocks from the one that was modified, and also keep up with the newly mined blocks by other miners in the network. In a network with high hashrate, that would become nearly impossible.

  3. How does the network regulate mining difficulty?
    By setting a lower or higher PoW puzzle solving target depending on the miners (hashrate) available in the network.

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#411

Homework on Mining and Proof of Work - Questions

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
  2. Why would it be very difficult for someone to go back change a previously added block?
  3. How does the network regulate mining difficulty?

To give them an incentive to maintain the rules and be rewarded in the future with higher rewards

All of the blocks that are connected to that block will change making it difficult to change and duplicate any transaction

By halving the cost every four years and setting the target lower everytime

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#412

  1. It is important so that there is such an enormous effort (penalty) for editing an older transaction and re-mining that block and all that come after, that the only logical way for a miner to make profit is to actually mine a new block for reward and fee.

  2. Because they would have to mine the block they edited again and all blocks that have been created after along with having 51% or more of the total hashing power in the bitcoin network.

  3. It regulates the difficulty based on the amount of miners in the network. The higher the difficulty, the lower the target needs to be and vice versa.

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#413

1, Mining uses a lot of electricity this costs miners upfront, so they are incentivised by being rewarded in payment for block rewards and tx fees.
2, Changing any data in previous blocks would break the links between blocks.Its impossible for anyone to catch up changing all the future blocks to get the previous block reinstated due to the computer mathematical implications and electricity usage.
3, More miners=higher difficulty making it harder to guess the nonce because of the lower target.

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#414

Why is it important to make sure that miners spend money (on electricity) while mining?

  1. To make sure the miners follow protocol and give incentives when they are rewarded for validation.

Why would it be very difficult for someone to go back change a previously added block?

  1. They would have to mine old blocks plus new blocks , this would take an enormous amount of power.

How does the network regulate mining difficulty?

  1. The difficulty is measured in hashes (usually terahashes – TH), concerning mining , it signifies the unit of work performed. The network hashrate or nethash (number of miners ) are measured by hashes per second (TH/s). The network itself adjusts difficulty in such a way that the difficulty /nethash = block time
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#415
  • Because this way miners keep working according to the protocol in order to obtain the reward.
  • I would say no, it is not hard to change a data. However, it is very difficult to remined all the blocks that have been affected by this action…The hash power that this would take would be too high and the time even more.
  • The more miners the more difficult it gets to resolve the puzzle and vice versa.
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#416
  1. To make sure the miners play by the rules, they are incentivsed to earn back the money they spend + intrest.
  2. You would have to re-mine all the block up till today, from the block you changed.
    3.The total hash power on the network determines the difficulty
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#417

The halving every 4 years is just about the reward miners get for mining a block. Difficulty gets regulated with adjusting the target every 2016 blocks. The more miners mine, the more difficult (so the target hash is lowered)

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#418
  1. have incentive to mine and solve the puzzle i.e. find the correct nonce to produce such hash taht is lower that the target hash for the respective block
  2. it “brokes the links” in the blockchain i… it changes the data whcih will lead to a new hash to that modified block going forward and changing next blocks’ hash. the remedy is very expensive teoretically and impossible practically becaus eit takes time during which time many othe rminer will build up longer blcokchain
  3. many miners - lower target - more difficult to guess the nonce such tah tyour block hash is lower than the tareget hash for the specific block
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#419

1.) The cost of mining is important because it means that bad actors need to spend and lose money if they break the rules.

2.) If a previously added block was changed, they would need to then change all blocks that came after it as well. And this would take a massive amount of computing power (51% attack).

3.) When Hashrate goes up, the target goes down - making guessing the nonce much more difficult. This essentially means the difficulty is much greater to mine a block.

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#420

  1. It encourages honesty because if a miner attempts changes/double spends it will cost them lots in electric expenses as their block will be rejected.

  2. Because they would have to re-mine all subsequent blocks and catch up with other miners looking for the same block reward. Would need massive amounts of hashrate to be successful.

  3. The block hash target difficulty is raised and lowered depending on how many miners are on the network. More miners increases difficulty=lower target

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#421
  1. Miners need to spend electricity in order to uphold Pow and solve the cryptographic puzzle that will find the nonce.
  2. Once a block is added the hash generated needs to match the previous one and the one before that etc. If the data is corrupted the hash will change everywhere and all the nodes in the network will reject the block.
  3. When the target is low the difficulty is high (many people are mining).
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#422

  1. It takes money to make money. By spending money to earn Bitcoin through mining, the network is incentivizing the miners to play by the rules and secure the network at all times.

  2. It would be very difficult (practically impossible) to change a previous block because each block in the chain contains the hash of the previous block. If any element of a given block is changed then the hash of that block will also change and it will automatically render all the blocks that follow invalid. In order to make this alternate version of the blockchain valid, the attacker would have to reconstruct the entire blockchain from that point onwards by finding the new hash of each block that follows the altered block.

  3. Mining difficulty is regulated by adjusting the target hash for the value that the miners need to find. The more miners in the network, the higher the difficulty.

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#423

1- Why is it important to make sure that miners spend money (on electricity) while mining?
Miners are incentivized. They make money in fees and rewards. But they have to spend money in electricity to put together the cryptographic puzzle by finding the nonce, which is a hash number lower than the target. The lower the target the more difficult it is to find the nonce. The more miners there are, the lower the target and the more electricity the miners need to spend money on. This motivates the miners to be honest and play by the rules, or the block won’t be accepted by the network and money will be lost.

2- Why would it be very difficult for someone to go back change a previously added block?
If something is changed in a block, the link will be broken, and consequently the following link and the following … etc… Then there’s a new cryptographic puzzle to figure out to make the blockchain make sense again. it has to re-mine and re-mine the other links and blocks. And this is impossible because it takes more than a life time to complete. And in the meantime, everyone will be mining other blocks and the network will pick the longest chain with most PoW.

3- How does the network regulate mining difficulty?
The miners in the network need to find a hash for the block. The block consists of the previous hash, a list of transactions and a nonce. The NONCE is guessing over and over again the hash, which must be lower than the TARGET. The more miners, the lower the TARGET and the more difficult it is to guess that hash number or nonce.

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#424

  1. The sending of money for Electricits gives the miners incentives to mine correctly.

  2. Because they need to remine every following Block up to the current Block.

  3. The Network lowers the Target so it is harder to guess the nonce.

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