What if all of the miners get the same answer?

[Dzwaafu11]

I researched bitcoin mining in depth. I realized that miners are competing to get the lucky solution by solving mathematical puzzles, but there is something behind these that I don't understand. Since there are many miners competing with each other, what's confusing me now is that what if these miners get the same answer at the same time?

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[BlackHatCoiner]

Explain more. What is "the same answer". I can think of various of things, so describe a little more about it, to avoid talking at length.

The "same answer" I believe you're referring to is the situation where two miners (or more) solve the block and broadcast it at the same time. In that case, some nodes will receive the miner A's block first, and some others will receive B's first. Both groups keep the other group's block, just in case. The miner who mines the next block gets to decide which of those two blocks is valid. Once he does, chain is reorged. This means that the chain with the unfortunate block is no longer followed.

[cruso]

If multiple miners find a valid block at the same time and broadcast it to the network, there can be a temporary split in the blockchain network. This is known as a "fork." The blockchain will eventually resolve the fork by accepting the longest chain, which is the chain that has the most computational work put into it.

This means that the miners who mined on the shorter chain will have their work invalidated, and they will not receive the mining rewards associated with that block. In short, only one of the competing blocks will ultimately be accepted by the network, and the miners who worked on the other block will have their work invalidated.

[Dzwaafu11]

Explain more. What is "the same answer". I can think of various of things, so describe a little more about it, to avoid talking at length.

I mean, if more than one miner mines the same block and gets the same solution at the same time, what is the solution? Will the network receive both blocks or will it consider one and ignore the rest?

[NeuroticFish]

Explain more. What is "the same answer". I can think of various of things, so describe a little more about it, to avoid talking at length.

I mean, if more than one miner mines the same block and gets the same solution at the same time, what is the solution? Will the network receive both blocks or will it consider one and ignore the rest?

The mathematical result doesn't matter much, as long as it's good. The problem is that all came in the same time. And then for short time everybody will consider as good his own block. Later on, the longest chain wins.
So on long term the rest are getting ignored. Only the one that gets a block added after it will prevail.

[BlackHatCoiner]

I mean, if more than one miner mines the same block and gets the same solution at the same time, what is the solution?

Okay, so I targeted right.

Will the network receive both blocks or will it consider one and ignore the rest?

Nodes will download and verify both blocks. They will not consider transactions in those blocks confirmed, they will wait until the next block is mined. Every block indicates what is the hash of the previous block (think of it like chain, hence the term "blockchain"), so the next block will determine which of these two blocks is the accepted one.

[digaran]

In simple term, the dad ( previous block ) does not want 2 kids, he only wants 1 kid, if there are 2 kids, one of them is orphaned. Such a cruel world, right?

[tromp]

ince there are many miners competing with each other, what's confusing me now is that what if these miners get the same answer at the same time?

Each miner adds their own coinbase tx to the new block. Since the block header commits to all txs in the block  (through the root of the tx Merkle tree), this means that each miner works on a unique header. And thus a unique Hashcash PoW puzzle.

In case of mining pools, the pool makes sure that different miners on the pool work on different headers as well, e.g. by giving them a unique block template.

[nc50lc]

-snip- Since there are many miners competing with each other, what's confusing me now is that what if these miners get the same answer at the same time?

That mathematical puzzle's answer is the Double SHA256 result of the block header.
For that to happen to competing miners, we're looking for a SHA256 collision which is highly unlikely to happen with the Bitcoin network's total hashrate.

[seoincorporation]

The "same answer" I believe you're referring to is the situation where two miners (or more) solve the block and broadcast it at the same time. In that case, some nodes will receive the miner A's block first, and some others will receive B's first. Both groups keep the other group's block, just in case. The miner who mines the next block gets to decide which of those two blocks is valid.

Great answer BlackHatCoiner, you always share great knowledge with the community, so, thanks for that.

I would think that works like the 51% attack, I mean, if more than 51% of the nodes receive block A then block B would be discarded... but now is clear that my theory is wrong.

And OP mentioned "All miners", just think about that scenario, lol, that would be like millions of orphan blocks at the same time, even if that scenario is impossible is fun to think how that would look like.

[BlackHatCoiner]

I would think that works like the 51% attack.

It doesn't work like a 51% attack, because a 51% attack is a conscious decision of reversing a block, whereas reorging happens often by chance.

I mean, if more than 51% of the nodes receive block A then block B would be discarded... but now is clear that my theory is wrong.

The percentage of nodes is irrelevant. What's relevant is the percentage of computational power devoted for mining on top of either block A or block B. If more than 50% of the hashrate is devoted on mining on top of block A, it's more likely that block A's chain will be followed later on.

[based52]

To commit work you need to include a public key that is used as the collection address for coin-base / mining rewards.
Assuming that you would never use someone else's key (or that the whole network would never use  a single public key) every commitment of work will LOOK different even if they (miraculously) ended up on the same hash collision. Not to mention the ability to publish this block means that they get to commit their transactions from the mempool to that block, therefore each block (contents) will also vary in how it appears to other nodes (regardless of the collision hash that might have been found by multiple miners).

[xzy887]

In simple term, the dad ( previous block ) does not want 2 kids, he only wants 1 kid, if there are 2 kids, one of them is orphaned. Such a cruel world, right?

Wow what a beautiful story. But what if the dad has the power to run the 2 kids equally? Then one more child will not be an orphan. Because the father has the proper power to run the two children, then both children will have equal rights to the father?
 Many have said, you have to choose any one?

[digaran]

In simple term, the dad ( previous block ) does not want 2 kids, he only wants 1 kid, if there are 2 kids, one of them is orphaned. Such a cruel world, right?

Wow what a beautiful story. But what if the dad has the power to run the 2 kids equally? Then one more child will not be an orphan. Because the father has the proper power to run the two children, then both children will have equal rights to the father?
 Many have said, you have to choose any one?

What? I don't know what this man is talking about, lol. That was an analogy I used, it's not applicable to the real mining scenario. The whole network operates on a certain sets of rules, when you mine a block, you are confirming the previous block making it more mature, those who mined the blocks back in the chain, would continue to stay with the block which has the more hash rate behind it, so yes if you have more power you could win the battle by building on top of the longest chain, and others would as well follow. But you can't keep the two blocks for yourself, because that will become a fork and creates a new chain.

Some kids in the past thought they have the power to fork away and stay successful, look at their miserable garbage coins now. Lol.

[xzy887]

In simple term, the dad ( previous block ) does not want 2 kids, he only wants 1 kid, if there are 2 kids, one of them is orphaned. Such a cruel world, right?

Wow what a beautiful story. But what if the dad has the power to run the 2 kids equally? Then one more child will not be an orphan. Because the father has the proper power to run the two children, then both children will have equal rights to the father?
 Many have said, you have to choose any one?

What? I don't know what this man is talking about, lol. That was an analogy I used, it's not applicable to the real mining scenario. The whole network operates on a certain sets of rules, when you mine a block, you are confirming the previous block making it more mature, those who mined the blocks back in the chain, would continue to stay with the block which has the more hash rate behind it, so yes if you have more power you could win the battle by building on top of the longest chain, and others would as well follow. But you can't keep the two blocks for yourself, because that will become a fork and creates a new chain.

Some kids in the past thought they have the power to fork away and stay successful, look at their miserable garbage coins now. Lol.

I also tried to convince you that one you can never run two blocks. Because if two blocks are executed, the previous block will be cut, the new one will continue. So you can't run two blocks simultaneously if you want. That is why I am saying that even if a father can give equal rights to his 2 children, I can never run two blocks together.