Homework on Mining and Proof of Work - Questions

[CalebMcClure25]

1. It is Important for minors to spend money on electricity because this incentivizes them to play by the rules and get rewarded financially.
2. Changing a transaction in a previous block would change the previous hash there for breaking the link between all blocks that came afterwards. Subsequently they Would also have to mine all blocks that came afterwards and play catch-up to the network still mining blocks.
3. The mining difficulty increases with more minors by decreasing the target value of the hash making it less likely to randomly find a number lower than the target hash.

[Marc]

1. By spending money the miners have incentives to follow the rules since they are invested in the mining process. If miners spend money on electricity, then they will want to be reimbursed by the rewards (block reward and transaction fees).

2. If anything is changed in the previous block it would break the link to the next and the following blocks. In order to change a previous block, all postceding blocks would have to be rehashed, but because a new block is formed every 10 minutes, it is nearly impossible to be able to rehash all future blocks fast enough.

3. As there are more miners the difficulty to guess the nonce is increased by lowering the target. The more miners there are the more the difficulty rate goes up to solve the cryptographic puzzle.

[alexhupe]

1. So that there is a strong incentive to provide correct blocks to the network and earn the block reward, in order to break even financiallay.
2. Because all blocks contain the hash of the previous block in the blockchain and the slightest change in any of the previous blocks would break the chain, forcing miners to re-hash for the next block. Therefore, the blockchain will not accept ammendments to previous blocks because they would be incompatible with the following block(s).
3. Blocks are appended at an average rate of once per 10 minutes. If this rate accelerates then the target will decrease, making the nonce harder to find, and slowing down the block generation rate. The target will increase if the rate of block creation slows (I.e., vice-versa).

[wfree02]

1. to properly incentivize the miners to make sure the blockchain integrity remains intact. Make them pay with loads of electricity upfront so that they will be incentivized towards honesty

2. Because you would then have to re-mine all the blocks that follow in the chain. Changing the data in a block changes the hash, which in turn changes the hash on the next block and so on. Would take too much energy to be profitable

3. By producing new block in intervals of 10 minutes as well as increasing or decreasing mining difficulty depending on the total hashpower present within the network.

[Mil_Pasos]

1. Why is it important to make sure that miners spend money (on electricity) while mining?
   It is important since they have money invested in elec costs, which incentivizes them to be honest and mine according to the rules and protocols where they can earn more money from the TX fees and Block Rewards.

2. Why would it be very difficult for someone to go back change a previously added block?
   Each block references the hash from the block before it and if something changes so does the hash , breaking the links to all blocks following the one changed. All blocks will have to be re-mined.

3. How does the network regulate mining difficulty?
   If the network is saturated it will lower the target which increases difficulty.

[TiffanyG]

1. It incentivises them to play by the rules and therefore they are willing to do the work in order to be compensated with monetary gains.
2. It would break the chain and all the while other miners would be creating new blocks. The amount of time and resources needed to re-do all the lost work would be immense.
3. The more miners there are, the smaller the target nonce is and that increases the difficulty. The opposite is also true.

[to_seeger]

1. For security. To assure that he plays by the rules and does not try to change the already confirmed blockchain.
2. He would need to invest a huge amount of computing power and therefore electricity to confirm the new block and every single following block. In the meantime new blocks are added all the time, so he would need to use an insane amount of energy.
3. By adjusting the guessing target. the lower the target the more difficult it is to guess a number below.

[Cyndium]

1. Why is it important to make sure that miners spend money (on electricity) while mining?
   To incentivize miners it is important to let the miners spend money to let them play by the rules.
2. Why would it be very difficult for someone to go back change a previously added block?
   Because you will have to re-mine the changed block and re-mine all the blocks that are new, this will take decades.
3. How does the network regulate mining difficulty?
   If there are a lot of miners, the target will be set low so is will be more difficult to match a hash. If there are very few miners the target will be set higher so it will become easier to match a hash

[trendy]

1. It is important that miners spend money on electricity because they will work to earn the incentives of Bitcoin and maintain the integrity of the network.
2. It would be very difficult for someone to go back and change a block because they would have to change every subsequent block thereafter. While the new blocks being created would continue to be mined creating an impossible way to catch up.
3. The network regulates mining difficulty through the use of the nonce being below the target. When the network is low the target is high and when the network is high the target is low, there for regulating the difficulty of guessing the nonce being below the target.

[dpturner]

1. The miners spend money on electricity for proof of work.
2. It would be difficult as you would have to change the hash for all previous blocks, which would be next to impossible.
3. It regulates the difficulty by requiring the guessing of a nonce and then setting the target for the hash.

[Emerik]

1. Why is it important to make sure that miners spend money (on electricity) while mining?
   Because doing this it’s like having a business where you have to invest before having profits. They are motivated to play by the rules to earn money, otherwise they could lose money instead of earning.
2. 1. Why would it be very difficult for someone to go back change a previously added block?
      If someone tries to change something in a previous block the hash number of that block will change as well, and all the links between this block and the next blocks will be broken, because every new block is build based on the hash number of the previous block. The miner should re-mine all those blocks
3. 1. How does the network regulate mining difficulty?
      It’s based on how many miners are in the network. More miners means lower target number,and a lower target number means higher difficulty to guess Nonce number

[turbodrakul]

1. If they spend money they want to get back + earn.
2. One step back creates new few steps forward in the same time. It is impossible to come back, catch up with it, cover costs and earn.
3. Challenge for miners to find a nonce in 10 minutes.

[Peter_Vongpaseuth]

1. Miners spend money on electricity while mining because they need a lot of electricity to create the blocks, solve the puzzle for the block and compete with other miners to make sure their block becomes the next block in the blockchain in order to earn their bitcoin.
2. In order to change a previously added block, the miner would to spend an incredible amount of electricity to change the hash of every block before the one being changed at the exact same time as he is changing the block he is trying to change.
3. The network regulate mining difficulty by creating an incentive that if the miners break the rules, they lose money through their electricity usage but if they follow the rules they will get rewarded.

[kristiandoble]

1. To incentivize honest behavior, where dishonest behavior by including invalid transactions are punished implicit by having electricity costs without getting any rewards
2. Because all blocks point back to the previous blocks. Changing the slightest detail in an old block, will change that blocks hash, and thus breaking the link between the blocks. In order to change a block successfully, you have to mine all blocks alone faster than the cumulative rest of the network
3. It regulates mining by the difficulty adjustment every 2 weeks, where the target is set lower if blocks on average have been produced faster than every 10 minutes

[Meddodreddo]

1. Why is it important to make sure that miners spend money (on electricity) while mining?
   Makes it costly to mine blocks, thus disincentivizing attempts to alter the blockchain since doing so is costlier as it would require re-mining the blockchain, additional cost of electricity to do so and ultimately a failing proposition unless theoretically more than 51% hash power is under an attackers control…which is prohibitively expensive for little reward once the bitcoin blockchain is compromised.

2. Why would it be very difficult for someone to go back change a previously added block?
   Unable to have to new/modified blockchain accepted by the network since the longest chain remains valid and a single person/entity cannot produce enough hash power to produce a new longer chain faster than the bitcoin network of miners.

3. How does the network regulate mining difficulty?
   By adjusting the target periodically based on the hash rate required to generate a newly mined block every 10mins.

[SG_miki]

1, so that they submit truthful information in there blocks and play buy the rules ,truthful blocks get rewarded
2,because if you change one thing every hash after that block would change braking links ,and this would take years to reconstruct
3, by how many miners are on the network and choosing a low target for miners to find nonce lower than.

[TEKluv]

• Homework - Mining & PoW

  • Why is it important to make sure that miners spend money (on electricity) while mining?
    Miners are incentivised to spend money on electricity by solving the PUZZLE ( nonce + tx + previously tx) and collecting fees and making some net profit after calculation. Only way is to be honest and play by rules.

  • Why would it be very difficult for someone to go back change a previously added block?
    To do this, they have to solve the puzzle again = nonce + TX + prev TX which will not have a positive effect on their net profit while mining difficulty grows. Let’s suppose the miner was succesful in changing a previous block however all the rest of the blocks coming after are inmediately invalidated and the miner should do the same for the rest. A miner will be left behind as new blocks the honest miners keep adding. Time is priceless be nice.

  • How does the network regulate mining difficulty?
    The network regulate mining difficulty by lowering the nonce making it harder to guess a lower number to complete the block.

[Maxwell]

1. By making the miners pay an upfront fee through expended energy, it incentivises them to make valid blocks as any incorrect data would be invalidated through consensus.

2. To amend a previous block would then involve re-mining all subsequent blocks to update their hashes, to do this and then catch up to the rest of the miners would be practically impossible unless you had a monopoly on the hash rate.

3. Mining difficulty depends on the number of active miners, the more miners the lower the number and the higher the difficulty to guess the nonce.

[maddie]

1. Why is it important to make sure that miners spend money (on electricity) while mining?
   That incentivices miners to be truthful so they can earn rewards and make their investment back and make a profit.

2. Why would it be very difficult for someone to go back change a previously added block?
   Because they would need to remine all subsequent blocks and catch up to the blockchain. The longest blockchain is considered the correct one. It would be impossible to create a longer blockchain on your own when everyone else is working to add new blocks to the chain.

3. How does the network regulate mining difficulty?
   It should take 10 minutes for a block to be mined. If fewer people are mining it takes longer and the target will be raised to lower the difficulty. If more people are mining it takes shorter and the target will be lowered to increase difficulty.

[Abdul_123]

1. Because it’s part of the rules set that they must follow so that they can in return be rewarded for solving the cryptographic puzzle in block rewards and transaction fees. Also, it acts as part of PoW and shows integrity within the network that every miner must follow.

2. Practically impossible since a change made in a block will affect the whole blockchain, as well as the cryptographic puzzles that they have previously solved. These puzzles form part of link made between each block and those links also relate to the contents of the each previous block. Thus, the miner would have to remine each block and solve each new puzzle which would take thousands of years (just like master Ivan mentioned in the video).

3. The more people mine within the network, the lower the target will be. This means that when you hash your nonce with your previous hash and transactions of your new block, and hash it to find the new hash, the chances of you getting a hash lower than target will be lower i.e. more difficult for your hash to be accepted thus more difficult for your new block to be accepted. In other words, mining becomes much more difficult.