 Gabriel asks, is it a rule of bitcoin or an average number based on computation power that blocks a form every ten minutes or so? Both. It is a rule of bitcoin that the average number of computation forms blocks every ten minutes. The difficulty of doing the calculation is adjusted every two weeks, so that the average number of blocks in a period of time is equal to a block every ten minutes. The way this works is, over a period of two weeks, there should be two thousand sixteen blocks. Therefore, we can count the previous two weeks and say, how many blocks were in the past two weeks? If the answer is two thousand sixteen, that means the difficulty of the algorithm and the amount of computation that people are committing to bitcoin mining is exactly right. It's perfect. Blocks are coming out every ten minutes, nothing to adjust. Now, let's say that instead of two thousand sixteen blocks, we had two thousand two hundred seventeen blocks. So, we had effectively ten percent more blocks. Well, in that case, the network will make the difficulty ten percent higher, exactly the same ratio as the number of blocks we had versus the number of blocks we should have, which is two thousand sixteen. If that difference is ten percent, then the difficulty algorithm will be adjusted by ten percent, and as a result, in future, we will get closer to ten minute blocks. If instead of two thousand sixteen blocks, we had one thousand eight hundred blocks, and we were short by two hundred blocks, well, then it's about ten percent short. We would adjust by about ten percent in the difficulty. That calculation happens every two thousand sixteen blocks, every two weeks, at exactly the same time, on exactly the same block, and affects the difficulty of the next block across the entire network. Every computer of the network puts in the number of blocks it saw over the last two weeks, measures the exact same number, adjusts the difficulty by the exact same amount, and arrives at the exact same answer, and so the entire network switches difficulty for the exact same amount every two blocks, every two weeks. Jimmy has a great question. Is it possible that the blockchain will not proceed or propagate because we come to a point where the difficulty required cannot be satisfied anymore in all of the iterations of the nonce and extra nonce? Yes, in fact, that has already happened. The reason we have extra nonce is because we got to a point where the difficulty could not be satisfied in the nonce. An extra nonce had to be changed. There are a number of other things in the block header that can be changed in order to produce more variation in the block header. The most important one, interestingly enough, is the order of the transactions and the types of transactions you include. Let's say you have two thousand sixteen transactions, or two thousand fifty transactions in your block. Just pick a number there. These transactions were received and put into the candidate block in a specific order. Because of the order of the transactions in the block, they are going to produce a very specific Merkle tree. Two thousand transactions, each pair of transactions, the first and second transaction, the third and fourth transaction, and the fifth and sixth transaction, are hashed together. Those hashes are hashed together until you get to the Merkle root up the tree. It is a binary tree. If you change two transactions at the bottom of the tree, just reverse the order, immediately the calculation changes all the way up. You get a different Merkle root. Effectively, that is like changing a nonce. You have changed the block header. All you have to do is flip two transactions around and recalculate the Merkle root. With two thousand transactions in the block, there are a lot of combinations of how you can order those to produce all kinds of variety in the Merkle root. Reordering transactions is one of the ways that miners can vary the header block when they run out of nonce and extra nonce. In fact, that is already happening. In this particular case, the reason it is happening is because of an advantage called ASIC Boost, which is a particular shortcut in the SHA-256 algorithm and the calculation of the mid-state in SHA-256. But the point doesn't really matter. The bottom line is that you can still satisfy the difficulty by varying other parts of the block header. It is very likely that over the next few years, we will see a change in the format of the block header. One of the things that will change in the format of the block header is giving more space for nonce, making a bigger nonce with more bits in it. There is no reason why that can't be done again, to continue to increase the difficulty. The amount of difficulty that can be calculated with hashes and the amount of nonce required can be satisfied. That is not a problem. MJ asks about the Bitcoin death spiral. Some believe that a combination of economic factors, such as crashing Bitcoin price or government actions, such as shutting down or outlawing mining, could cause a sudden and sustained reduction in mining cash power. What threat would this pose to Bitcoin? Could it cause a death spiral as some fear or hope? The death spiral phenomenon is this. Because this is not calculated based on time, it is calculated every 2016 blocks. I assume that mining power drops dramatically. Let's say it drops by 50%. At 50% of miners participating, blocks are now coming out every 20 minutes instead of every 10. Because it is every 20 minutes instead of every 10, it won't take two weeks to recalculate the difficulty to adjust that back to 10 minutes. It will actually take four weeks, because it will take four weeks for 2016 blocks to be produced. A sudden and sustained reduced in hashing power will cause a sudden and sustained increase of the time per block, which will cause a sudden and sustained increase of the interval until the next difficulty retargeting. Of course, some people assume that if that happens, a lot of miners will say, okay, I'm not making enough profit anymore because the hash rate has dropped by 50% and things are moving a lot slower. I'm going to turn off my mining, which then causes it to drop even further, which causes it to get even slower, which causes it to drop even further, get even slower, drop even further, even slower. That spiral never adjusts. First of all, part of the reason that's unlikely to happen, and we've seen that in other chains that have suffered from this sudden reduction in mining power, is that miners have a much more long-term perspective, meaning that they have an existing investment in equipment, and they usually purchase electricity on long-term plans. They don't pay for it by the week. Therefore, if they have to wait to become profitable another three months, and they already have the equipment in place, they're not turning it off. They're going to return to profitability. In fact, if they wait until the difficulty retargets and the difficulty becomes less, it gets easier to mine, then each miner who waits makes more profit, because in the new scheme they have a greater percentage of the mining power than they did before. Let's say the mining power drops by 50%. The miners who stick around and wait for the difficulty retargeting, are now twice as profitable after the retargeting. That's a pretty good incentive to stick around. The other reason that this is unlikely to happen is that it assumes that, in this process, the rest of the network simply sits by idly and no changes are made to the protocol. Arguably, if you had such a drastic reduction in hash power, the time to the difficulty retargeting was pushed far, very far. One of the answers, and we've seen this happen in other blockchains, is to change the retargeting algorithm. This happened in Bitcoin Cash, in fact. There was a situation where the difficulty was being retargeted far too often, and a hard fork was made to change the difficulty retargeting algorithm. Changing the algorithm to make the difficulty be retargeted sooner is something that could be done, as long as there's a big enough reason that everybody agrees it must be done. You have to achieve consensus. In order to avoid a fork, everybody has to agree on the new difficulty retargeting, otherwise those who disagree will end up on a different fork. Arguably, yes, this could fork Bitcoin, but it's more likely that you'll have an overwhelming support for changing the difficulty retargeting algorithm if it becomes a big enough problem. Again, I think the term Bitcoin Death Spiral in itself produces this fantastic dark image. It's a very strong, emotionally triggering term. People don't think, oh, this is a terrible thing that could happen. The chances of it actually happening are pretty low. The chances of it happening and nobody doing anything about it to fix it is near zero. I don't think we have anything to fear from this situation of difficulty retargeting. Do you think there will ever come a time when the Bitcoin crypto economy is so large that controlling a proportion of the mining capacity will be considered a central bank responsibility and or national security issue, where, for example, the United States, European Union, China, Russia, etc. would be running state-controlled mining operations competing against each other? Or do you think mining will remain in the hands of private enterprises for the foreseeable future? Or perhaps states will seize privately-owned mining facilities and forcibly take them into public ownership? Well, Colin, here's the thing. There is something to be said about the possibility of state entities taking over private mining facilities and turning them into state-owned enterprises. You would think that, because this is a wide-open free market, where both energy use and mining can be done anywhere, where usable electricity is difficult to distribute or delivered in excess of local demand, can be utilized. You would think that in such a free market, the distribution of mining would follow free market principles. If you took it over and turned it into a state-owned enterprise, it would be extremely likely that state-owned enterprise would be less efficient than its private counterparts. Effectively, this would be the state sinking a lot of money into building a failed national infrastructure and industry. However, that would be okay if the production of electricity wasn't in many cases highly monopolistic and highly state-owned. This isn't a level playing field entirely. There might be some advantages for some state entities to nationalize mining and use that in conjunction with the nationalized energy infrastructure in order to gain some strategic advantage. Of course, the ironic thing here is that the strategic advantage in this particular case wouldn't be taking over or changing the rules or trying to interfere with Bitcoin, because as I mentioned in a previous answer, that would fail, and it would fail so spectacularly and in such a costly fashion. However, consider it this way, what if the national interest would be to maintain the neutrality of the protocol, to not allow anyone else to take it over, to present a level of mining that insured neutrality by resisting attempts to centralize mining? That's an interesting possibility. I don't think it's entirely out of the question that you might see large state actors eventually doing state-level mining. I don't think they're going to be very competitive, but they could use their control over energy industry to do that. I don't know if that's a good thing or a bad thing to the crypto economy. I don't think it's a bad thing simply because they would have to follow the rules like everybody else. If they tried to break the rules, they would face a catastrophic network-wide change of the proof-of-work algorithm. There's always that. The nuclear option, as you might consider it.