Homework on Mining and Proof of Work - Questions

Blockchain and Bitcoin 101
#907

It is important to make sure that miners spend money (on electricity) while mining because
their incentives are aligned to not cheat the network system.
It would it be very difficult for someone to go back and change a previously added block because of the one way hash and other miners in the network.

The network regulates mining difficulty by producing a block each 10 minutes. This is done by making an easier mathematical problem to solve, as the time runs out.

#908
  • Why is it important to make sure that miners spend money (on electricity) while mining?

So that they are incentivised to get the block reward and make money from the money and effort they have put into mining.

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

Because the hash of a block is based on the hash of the previous block and the tx’s that were in it. So changing one thing in a block would make the next hash invalid.

  • How does the network regulate mining difficulty?

By setting the target low when the difficulty is high. When the difficulty is high, this means there are many miners mining. This means miners need to have great computing power to hash a block when the target is low. When the difficulty is low, not so many miners operating, the target is set high and thus a block is easier to mine.

#909
  1. PoW, Integrity and guessing Nonce to mine a new block.
  2. It would take an eternity to rework all the blocks broken in the chain and you would lose time and money.
  3. Target…target is low when difficulty is high. Miner spend more time guessing Nonce when difficulty is high.
#910
  1. Why is it important to make sure that miners spend money (on electricity) while mining?
  • If the block is rejected, they have spent electricity for nothing, therefore it makes more sense for miners to follow the rules and make legitimate blocks.
  1. Why would it be very difficult for someone to go back change a previously added block?
  • Because it would change all the blocks after it. In that case, you would have to re-mine them. Meanwhile, others keep mining legitimate blocks at a much faster rate. As the longest chain is accepted, the altered one would never win.
  1. How does the network regulate mining difficulty?
  • A hash is a random, unpredictable number from 0 to eternity. It is altered by adding a nonse (random string) to the block and rehashed. A block is accepted if its hash is lower than the difficulty target.
  • If the time period between blocks tends to be more than 10 minutes (puzzle too difficult), the target is raised (more correct answers possible). If too easy, the target is lowered.
#911

  1. Keeps them honest. They will not want to waste time trying to cheat as this is nearly impossible when they can make money mining.

  2. Because if one block is changed, each and every following block must also be changed which is infeasible.

  3. If there are many miners, difficulty increases as hash lowers making it more difficult for miners to guess nonce.

#912
  1. Miners will be needing the incentives to make money. when no incentives are received they will only spend and go out of business.
  2. when going back to a previous block and change the content, the hash will change. this hash is used for the next connection and also will change. the miner will need a lot of computer capacity to get back in line. It would actually cost more than just playing by the rules.
  3. the hash of the new block is determined by three factors: previous hash, the data of transactions and the puzzle, which is nothing else than a random number. this number is a guess of the miner and is between 0 and infinity. The lower the number the more difficult the puzzle. the number is regulated so that approximately every ten minutes a new block is added to the chain.
#913

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

MIners put up a stake to mine, that stake is cost of electricity, miners are now incentivized to mine by the rules and in an expedient and efficient manner to solve the hash / puzzle first for each block they are mining

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

Once any change is made to a previous block, no matter how minor, the hash changes and the chain is broken, now the block needs to be rehashed and all the blocks succeeding blocks, meanwhile miners are adding new blocks down the chain and you are basically lost trying to alter an deterministic, immutable finalized one way ledger, doesn’t matter if your trying to alter a billion $ transaction, the cost in energy alone will be more, if you had 51% + control of all the nodes on the network you might be in business

3. How does the network regulate mining difficulty?

The more miners on the network the target (nonce #) goes lower, the lower the target, the smaller the #, the more difficult to solve, guess the nonce

#914

Why is it important to make sure that miners spend money (on electricity) while mining?
There needs to be a cost in order to force miners to follow the rules. Cheating the system will cost more(wasted electricity) than to mine honestly to be profitable and cover the cost of electricity

Why would it be very difficult for someone to go back change a previously added block?
Longest chain is the true chain. If you attempt to change a block you will need to mine every subsequent block to catch up to the current block. This is wasted time and energy

How does the network regulate mining difficulty?
By increasing or decreasing the difficulty of mining depending on the number of miners mining. More miners on the network increases difficulty whereas less miners lowers the difficulty

#915

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

So that they are incentive by money to maintain the integrity of the network, if they solve the puzzle first but then attempt to create a bad block it will be rejected. This whole scheme doesn’t sound very good from a green/save the planet point of view :wink:

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

Each future block would also need to be changed, this would be too costly.

How does the network regulate mining difficulty?

The difficulty of the puzzle changes, depending on how many miners are mining.

1 Like
#916
  1. It is important for the network security. So if miner will try to break the rules, they will loose money.
  2. It will be difficult, because you need to remine all the blocks which was mined after that block and plus the ones which are newly mined, it can take thousands of years to do that. It is practically impossible to catch up.
  3. Difficulty is measured by how many people are mining.
#917

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    because it’s the proof that they worked in order to generate the new block and therefore they deserve rewards, besides if miners try to cheat they will get a non accepted block and they loose the mining costs

  2. Why would it be very difficult for someone to go back change a previously added block?
    because it changes the block hash of that block and therefore all the hashes of the next blocks. In this case the only way to keep that blockchain up would be to mine all the modified blocks plus the new ones created.

  3. How does the network regulate mining difficulty?
    the more hashing power (power of mining) the higher is the difficulty and therefore the lower is the target number which will have an additional 0 in front of it for each level of difficulty

#918
  • Why is it important to make sure that miners spend money (on electricity) while mining?
    To make sure they follow the rules of mining.
  • Why would it be very difficult for someone to go back change a previously added block?
    To avoid fraud (double spend). You need to resolve the previous and new links in the blockchain with mining what will take years
  • How does the network regulate mining difficulty?
    Lowering the hashrate depending on the amount of miners and transactions to be placed on a block
#919

Using a lot of electricity to solve the cryptographic puzzles guarantees that miners will follow the rules/protocol because they will only be rewarded if they do. If they fail to follow protocol they will not be rewarded and solely be spending money on electricity for no reason.

It would be very difficult for anyone to do so because every block thereafter would have to be “re-hashed” or “re-linked” ,while all other miners on the network already would be blocks ahead of them and it would take them hundreds or thousands of years to catch up, if they ever could.

Mining difficulty is determined by the worldwide hash rate, more miners = higher difficulty.

#920
  1. It’s important to make sure that miners spend money while mining as will increase the security, transparency and authenticity of the block that they are mining.
  2. If someones make changes to a block, it will completely destroy the link between blocks, and those blocks would it have to mined again, it will be very costly and it can take that miner from the blockchain.
  3. The network regulates mining difficulty by the hashing function meeting the target.
#921
  1. Why is it important to make sure that miners spend money (on electricity) while mining? For them to earn block reward and TX fees, they must spend electricity to ensure honest blocks be appended into the blockchain.
  2. Why would it be very difficult for someone to go back change a previously added block?
    Each block has the previous hash data. If one block is changed from point A, then point B through Z will all be changed. They will have to remine each block again spending huge amounts of electricity and money just to change it. That is why it is easier to make BTC if they are honest instead of dishonest.
  3. How does the network regulate mining difficulty? The network regulates the mining difficult with a target that miners must guess. For instance, if the target number is high, then the miners will have an easy difficult to guess the number. However, if the target number is low, then the miners will have a higher difficult to guess the number.
#922

  1. Its important for them to spend money on a recourse. This way they are incentivised not to cheat.

  2. The blocks build on each other. The previous blocks hash is always part of the new block. So if one block is manipulated it wouldn’t get accepted by the network.

  3. Few miners means low difficulty as the nonce is a higher number. At lot of miners would result in a higher nonce and thus a longer time for a single node to mine a block. Also if the blocktime goes above 10min, the difficulty will drop.

#923

1. Why is it important to make sure that miners spend money (on electricity) while mining?
a. By spending money on electricity in advance, miners are incentivized (or encouraged) to abide by the rules established by the protocol
2. Why would it be very difficult for someone to go back change a previously added block?
a. Any modification on a previous block would invalidate the links created for the following blocks. Even the slightest change in the previous block will produce a new hash, so the block that follows would be invalidated, because it was created from the original hash of the previous block.
3. How does the network regulate mining difficulty?
The more miners there are - usually represented by the hashrate - the higher the difficulty is on the network. The protocol aims to create a new block every 10 minutes, hence the difficulty is adjusted at regular intervals to keep in line with this rule

#924

1.It is important that miners spend electricity so they will correctly build new blocks in order to get the reward.

  1. It would be practically impossible because then it would be necessary to build all the broken blocks, in meantime there are other many miners building longer chains that would be rather appended to the blockchain.

  2. Miners are guessing the nonce until the hash of the block is lower than the target. The difficulty is higher when the target is lower.

#925

  1. Because we want miner to follow the rules and following the rules will keep the network reliable, efficient and secued.

  2. Because it is practically impossible to go back and solve the puzzle in each block. Remember once one block has been broken it will automatically affect other blocks because they are all connected in parallel. Even if its theoretically possible, the miners will spend times, huge amount of money and still won’t be able to meet up because each must have been produced after the previous block.
    well i don’t think a normal human being will want to start such endless journey.

  3. The more the miners , then the more the difficulties, the less the miners then the lesser the difficulties.

#926

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

Because when they spend money on electricity, they want to make profit of mining, and it comes when they are honest and play by rules. If they do so, they can have the block reward and fees.

2-Why would it be very difficult for someone to go back change a previously added block?
Because the blocks are connected in a special way. The hash of a block depends on the previous block hash, the content (transactions) and the nonce. When something is changed, the hash will change and the next block will change and so on.

3-How does the network regulate mining difficulty?
The difficulty is set by the target. The lower it is, the more difficult to get a hash below it.