Homework on Mining and Proof of Work - Questions

Blockchain and Bitcoin 101
#4420
  • Why is it important to make sure that miners spend money (on electricity) while mining?

It builds incentive for them to follow the rules and earn money.

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

It will require incredible amount of energy and this request will grow exponentially as other blocks will be produced in the original chain.

  • How does the network regulate mining difficulty?

More miners, higher difficulty->reward is low->
Less miners, lower difficulty->reward is high->More miners…

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#4421

  1. Its important because we need some incentive for the miners to abide by the rules and do their work properly, so that they want to get the amount of money they spend in the process of mining back.

  2. Changing the previously added block would change the newly established and all that follow due to a change of hash in the system that links the blocks with one another. One would have to remine all the blocks that come after the block one changed, also the ones that are yet to come in order to keep everything error free.

  3. The network regulates mining difficulty by by setting the target according to the amount of miners that are actively trying to guess the correct nonce. The more Miners the lower the target and vis versa.

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#4422

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    -To ensure the miners follow the rules and earn the incentives. Also to show PoW.

  2. Why would it be very difficult for someone to go back change a previously added block?
    -Any changes in a previous block breaks every link and change every block after it. A new PoW must be created for the block being changed and every block after.

  3. How does the network regulate mining difficulty?
    -More miners=lower target=higher difficulty. Low target=higher difficulty.

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#4423
  1. By spending money the miners have incentives to follow the rules since they are invested in the mining process.
  2. If anything is changed in the previous block it would break the link to the next and the following blocks.
  3. As there are more miners the difficulty to guess the nonce is increased by lowering the target.
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#4424

  1. In order for miners to be honest and truthful to work towards incentives in order to make profits.

  2. It would be very difficult for miners to go back to change previous blocks and then catch up to the latest blocks. The time and electricity would be better spent in being honest and gaining incentives.

  3. By increasing miners it means the more difficult it becomes to guess the nounce on the network by lowering the target.

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#4425
  1. To provide an incentive for miners to follow the rules of the blockchain and not cheat.
  2. Attempting to change a previous block would require recomputation of all subsequent blocks.
  3. The nonce regulates the difficulty of the computations needed for the hashing.
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#4426

  1. It is important to make sure miners spend money on electricity while mining, so that there is an incentive to play by the rules. For example, if you try to create illegitimate blocks, your illegitimate blocks will be rejected by the rest of the network, rendering your efforts and computation power yieldless.

  2. Each block is cryptographically linked to the previous block via hashing, therefore to change one block would mean you’d have to re-mine each block prior to that block. This would cost a lot of electricity and the network will reject your chain.

  3. Mining difficulty is regulated in the following manner, the more miners there are, the harder it is to have your block added to the chain, the less miners there are, the easier it is to add your block to the chain, this is done via the lowering/raising of the target. The difficulty is adjusted so that 1 block is created every 10 minutes.

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#4427

  1. It is important to make miners spend money on electricity so they will have an incentive to to stay honest and be able to cash in on block rewards to pay for their expenses and earn a profit.

  2. It would be difficult for someone to go back and change a previously added block because blocks are derived from information in all previous blocks and any change, no matter how small will affect the hash of that block and any that follow. This would then require changing all blocks in the blockchain before new blocks are added which is virtually impossible.

  3. The network regulates mining difficulty by adjusting the mining target. The higher the number of miners there is, the lower the target and the higher the difficulty.

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#4428

1.its a way to make the miner not try and cheat a block for the rewards, because it will cost them if they get it wrong. makes it more efficient to do it legit.
2.they would never be able to catch up fast enough to change the newest block. unless they had 51% or more of the network
3.by the hash

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#4429

1. Why is it important to make sure that miners spend money (on electricity) while mining?
This incentivizes the miners to “play by the rules”. Otherwise they could mess with the block chain data with no repercussions.

2. Why would it be very difficult for someone to go back change a previously added block?
If they change a previous block then they have to rehash all of the data on that block and then re-hash the data on all the subsequent blocks on their own. As Ivan said: it’s theoretically possible but not practically possible.

3. How does the network regulate mining difficulty?
It adjusts the difficult by adjusted the “target” number based on the overall network hash rate.

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#4430

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    To make sure the miners have to invest a lot of money upfront in order to keep them honest (i.e it will be very expensive and ROI negative to “cheat” on a transaction).

  2. Why would it be very difficult for someone to go back change a previously added block?
    When a transaction in a previous block is changed, it changes the hash of that block and all the consecutive block hash would change. Thus, the chain will be broken and all blocks need to be re-mined.

  3. How does the network regulate mining difficulty?
    The network adjusts the target based on the number of miners. The miners have to randomly guess a nonce and hash it with the current transactions + hash from previous transactions. If this output hash is less than the target, this block gets added to the blockchain.

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#4431
  1. For the Proof of work, to get paid by fees + block reward later (they spend electricity by coding a new block in the blockchain)
  2. Because it would change the whole suite of the blockchain. So he would have to guess a new nonce for the modified block, and then all after him. It is basically impossible because he wouldn’t have time to “correct” a block since hundred are created every 10 minutes.
  3. As they are more minters, the target is lower so it is more difficult to guess the nonce.
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#4432
  1. Money is the incentive. The miners pay electricity upfront, so their blocks can’t contain any faults otherwise they won’t get rewarded in btc.
  2. Because if you change a previously added block, all other blocks after that have to be mined again since the hashes have changed.
  3. More miners = lower hash target = more difficulty mining.
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#4433

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    The more money they spend upfront for the electricity the more they will follow the rules so they can get their incentive when their block is added to the blockchain. If they don’t follow the rules the block will be rejected and they will not receive the block reward and the fees from transactions while they already spent a lot of electricity meaning they will lose money. That also means securing the network, by abiding the rules to be able to get the rewards.

  2. Why would it be very difficult for someone to go back change a previously added block?
    Blocks are made by the tx list and the previous hash and linked together, by trying to change something in a previous block the hash of that block will change and will affect all the rest of the blocks forward. That will mean from the block that was changed every single block will have to be mined again while also trying to catch up with the newly added blocks, which makes it impossible in practice because of the amount of time and work that has to be put in.

  3. How does the network regulate mining difficulty?
    The more miners in the network = lower target = more dificult to guess the nonce

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#4434
  1. By spending money, miners are incentivized to follow the protocols of the bitcoin network as they are invested in the mining process.
  2. If any data is changed in a previous block, it breaks links to the superseding blocks.
  3. If there are more miners in the network the difficulty increases, meaning the difficulty to guess the nonce is increased as the target is lower.
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#4435
  1. When you’re invested in mining, the only way you will be compensated or make a profit is following the rules, ignore the rules and you wont be compensated. It would be reckless to invest into something and not make any money.
  2. Then you’ll have to change every block from the one you are going to change and so to the other blocks after that and they have to be remined and try and catch up to the new blocks being confirmed, this may take too long.
  3. When there’s more miners the difficulty to guess nonce will be higher because target is lowered.
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#4436
  1. The upfront cost of PoW incentivizes miners to play by the rules for fear of losing investment.
  2. Not only would one have to resolve the UTXO’s, whose numbers wou;d change, there are additional maths to be solved- all this while legit miners are solving current blocks. While theoretically possible, it is impractical and not profit efficient.
  3. This is a control mechanism to regulate inflation.
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#4437

1.) It gives miners a vested interest in solving the puzzle and inventivizes them to prove their work.

2.) For a few reasons…any changes subsequently change the hash of the affected transactions, which in turn change the final hash output of the block, all together. That would sever the link to the connected blocks. And, also, the complete randomness of NONCE,

3.) Mining difficulty is proportionate to the number of miners mining at the time. The more miners present, the lower the target number and the fewer miners present, the higher the target number. That is the hash value number that miners must fall below, after they add their nonce.

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#4438 
1- Why is it important to make sure that miners spend money (on electricity) while mining?

If they dont have to spent money upfront they are not motivated to play by the rules and will produce a lot of buggy / false blocks (Blocks with invalid transactions)


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

Because then all following blocks have to be remined again, all following block and link hashes are broken. beacuase thye depend on the previous ones. This needs a lot of calculation power = electricity = money.
In the meantime the valid nodes (unmodified) will build new valid blocks. And the ledger ist constructed in a manner that alwals the longes blockchain will be taken as truth

3- How does the network regulate mining difficulty?

the more miners are particitating the higher he difficulty will become which means the target number which the calculated hashcode has to underbid will be lowered.
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#4439
  1. Why is it important to make sure that miners spend money (on electricity) while mining?

So miners are incentivized to follow the rules of the ledger, due to spending money on electricity for the solution of the Hash puzzle. They are invested upfront so if they don´t play by the rules and their block is rejected, due to invalid transactions, they loose money because they don´t get the BR´s + tx fees.

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

It is practically impossible, because one would have to again solve all puzzles from following blocks and all blocks being added in the time one is solving those puzzles, due to the hash of the block being based from the tx list and the previous block´s hash. It would take thousands of years to solve.

  1. How does the network regulate mining difficulty?

The more miners there are, the harder it gets to guess the correct nonce, due to the target being lowered, in order to prevent the miners from adding more than 1 block to the chain every 10 minutes.

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