What if a large number of miners were suddenly forced to shut down?

[teukon]

95% of miners are suddenly offline.
Be it a new law or an EMP strike. What would happen to bitcoin?  

Confirmation of transactions would take longer untill we hit the next difficulty adjustment. After that difficulty would be decreased. I am not 100% certain if there is a maximum the difficulty can change per adjustment, but I suspect there is.

There is.  The difficulty may not increase or decrease more than 4-fold.  If the hashrate drop occurs when we're more than about 400 blocks from a difficulty change and the hashrate stays down then we'll endure a few months of 8-block days (1 block every 3 hours on average) before retargeting to grind through 2 months of 45-minute blocks.

In its 6-year life Bitcoin has only once experienced a full 4-fold difficulty change.

[1714770705]

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[1714770705]

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[gogxmagog]

i'd simply dust off and plug back in my 60 Ghs miner and watch the btc roll in. right now it is not worth the electric it draws.
but of course there are scores of others who would do the same, the question is essentially moot.

I'm not sure why you post such folly, I dont believe you are looking to better understand anything or honestly care what would happen. More likely you are working on building your account rank and activity so you can rent your sig out or even sell the account to trolls. I can understand that you are reduced to actually starting your own pointless threads because there are so many shadow accounts like yourself, posting drivel, that it can be hard to find much to interact with...they are all making shit posts and the forum becomes a wasteland.

I wonder what would happen if a large number of bitcointalk troll/shill/puppet accounts were suddenly forced to shut down?

[Lauda]

Well this is a silly question that was asked over and over in the past. Start using search.
An EMP to hit out 95% of the miners, would need to be an EMP around the whole world thus wiping out 100% of the Miners and everything else. That would create chaos in which no currency would matter at all.
As far as all other things go, there is no way that someone could force 95% of the Miners to shut down. There are just no possible means of achieving this.

So what would happen doesn't really matter, because it won't happen.
~Lauda

[funtotry]

95% of miners are suddenly offline.
Be it a new law or an EMP strike. What would happen to bitcoin?  

Confirmation of transactions would take longer untill we hit the next difficulty adjustment. After that difficulty would be decreased. I am not 100% certain if there is a maximum the difficulty can change per adjustment, but I suspect there is.

There is.  The difficulty may not increase or decrease more than 4-fold.  If the hashrate drop occurs when we're more than about 400 blocks from a difficulty change and the hashrate stays down then we'll endure a few months of 8-block days (1 block every 3 hours on average) before retargeting to grind through 2 months of 45-minute blocks.

In its 6-year life Bitcoin has only once experienced a full 4-fold difficulty change.

Are you sure about the difficulty not being able to decrease by more then 75% in one adjustment? I know that one of the early adjustments almost was 4x and satoshi mentioned that it was close to the limit, however I have never seen anything regarding there being any limits as to how much the difficulty can go down.

[teukon]

95% of miners are suddenly offline.
Be it a new law or an EMP strike. What would happen to bitcoin?  

Confirmation of transactions would take longer untill we hit the next difficulty adjustment. After that difficulty would be decreased. I am not 100% certain if there is a maximum the difficulty can change per adjustment, but I suspect there is.

There is.  The difficulty may not increase or decrease more than 4-fold.  If the hashrate drop occurs when we're more than about 400 blocks from a difficulty change and the hashrate stays down then we'll endure a few months of 8-block days (1 block every 3 hours on average) before retargeting to grind through 2 months of 45-minute blocks.

In its 6-year life Bitcoin has only once experienced a full 4-fold difficulty change.

Are you sure about the difficulty not being able to decrease by more then 75% in one adjustment? I know that one of the early adjustments almost was 4x and satoshi mentioned that it was close to the limit, however I have never seen anything regarding there being any limits as to how much the difficulty can go down.

Nice to know someone's paying attention.

Well, certainly the intent is for a difficulty change to be limited between 25% and 400%.  Here's the code in the reference client responsible for this.  Technically, a difficulty rise might ever so slightly exceed 400% due to some rounding which is done to keep block-header size down, but this won't be more than by about 1 part in 10 million and will not allow a breach of the 75%-drop limit.

Bitcoin's difficulty increased precisely 4-fold on 16th July, 2010 with block #68544.

Block #68543 has a "bits" value of 0x1c05a3f4 (470131700 expressed in hexadecimal) where block #68544's bits value is 0x1c0168fd.  The bits value is a 32-bit compact representation of the 256-bit target (the value below which a block's hash must be for it to pass the proof-of-work requirement).  The corresponding target values are:

Code:

0x0.05a3f4 * (0x100 ^ 0x1c) = 0x0000000005a3f400000000000000000000000000000000000000000000000000 = 92413 * 2^202

and

Code:

0x0.0168fd * (0x100 ^ 0x1c) = 0x000000000168fd00000000000000000000000000000000000000000000000000 = 92413 * 2^200

The target dropped precisely 4-fold here.  This corresponds to a 4-fold increase in difficulty from

Code:

45.3858223410126280934500557280902037592113663662038890632270351573...

to

Code:

181.5432893640505123738002229123608150368454654648155562529081406295...

[ScryptAsic]

Well this is a silly question that was asked over and over in the past. Start using search.
An EMP to hit out 95% of the miners, would need to be an EMP around the whole world thus wiping out 100% of the Miners and everything else. That would create chaos in which no currency would matter at all.
As far as all other things go, there is no way that someone could force 95% of the Miners to shut down. There are just no possible means of achieving this.

So what would happen doesn't really matter, because it won't happen.
~Lauda

This is almost certainly correct. It would be very unlikely that any event would knock out the vast majority (95%) of the mining network but not the internet (which is required in order for the miners to wish to continue to mine as without the internet they will have no way of broadcasting their blocks and no way of knowing what the latest block that has been mined is).

I would "accept" scenarios in which much smaller portions of the mining network are taken offline, but not 95%

[altcoin.center]

95% of miners are suddenly offline.
Be it a new law or an EMP strike. What would happen to bitcoin? 

A very interesting question indeed.

I've been pondering upon related issues here:

https://bitcointalk.org/index.php?topic=812863.0

...and also give my couple of cents in an article that handles the EMP/CME issue here:

https://www.cryptocoinsnews.com/hamradiocoin-crypto-via-radio-alternative-blockchain-channel/

- Jyri
--
Altcoin.Center

[altcoin.center]

Well this is a silly question that was asked over and over in the past. Start using search.
An EMP to hit out 95% of the miners, would need to be an EMP around the whole world thus wiping out 100% of the Miners and everything else. That would create chaos in which no currency would matter at all.
As far as all other things go, there is no way that someone could force 95% of the Miners to shut down. There are just no possible means of achieving this.

So what would happen doesn't really matter, because it won't happen.
~Lauda

This is almost certainly correct. It would be very unlikely that any event would knock out the vast majority (95%) of the mining network but not the internet (which is required in order for the miners to wish to continue to mine as without the internet they will have no way of broadcasting their blocks and no way of knowing what the latest block that has been mined is).

I would "accept" scenarios in which much smaller portions of the mining network are taken offline, but not 95%

Both me and a significant portion of scientists specialized in events related to Sun and the geomagnetic field would disagree.

It is instead a well known fact that a big CME will eventually blow the lights out of possibly whole continents.

I've been involved in a very high level team mapping the significance of this issue on a national level and I can assure you it's not some fringe theory. It's been taken very seriously on very high levels of governmental decision making.

Not that mining crypto currencies would be nearly the biggest problem should/when the scenario plays out. There's going to be plenty of much more urgent stuff to concentrate on.

- Jyri
--
Altcoin.Center

[bajlox]

If this happen you have several possible scenarios.
From price goes sky high to price go to low or even price stay on where it will be in time of this.

Also interesting topic to discuss and sure this can happen someday.

[azguard]

95% of miners are suddenly offline.
Be it a new law or an EMP strike. What would happen to bitcoin? 

That is impossible to happen and even if it would, nothing impotant would happen , new miners would rush for free money.

So you are saying there is an equivalent of 95% of todays hashingpower somewhere in a warehouse just waiting for this to happen?

He thing there is.
Seriously all rigs are scatter over the world not on one place.
If there were on one place you dont need EMP you can blow up with any explosive.

[anshar]

It would take several months I think for the remaining miners to find a new block as the difficulty would not adjust for some time until enough blocks are found.

[AnonBitCoiner]

Well this is a silly question that was asked over and over in the past. Start using search.
An EMP to hit out 95% of the miners, would need to be an EMP around the whole world thus wiping out 100% of the Miners and everything else. That would create chaos in which no currency would matter at all.
As far as all other things go, there is no way that someone could force 95% of the Miners to shut down. There are just no possible means of achieving this.

So what would happen doesn't really matter, because it won't happen.
~Lauda

This is almost certainly correct. It would be very unlikely that any event would knock out the vast majority (95%) of the mining network but not the internet (which is required in order for the miners to wish to continue to mine as without the internet they will have no way of broadcasting their blocks and no way of knowing what the latest block that has been mined is).

I would "accept" scenarios in which much smaller portions of the mining network are taken offline, but not 95%

Both me and a significant portion of scientists specialized in events related to Sun and the geomagnetic field would disagree.

It is instead a well known fact that a big CME will eventually blow the lights out of possibly whole continents.

I've been involved in a very high level team mapping the significance of this issue on a national level and I can assure you it's not some fringe theory. It's been taken very seriously on very high levels of governmental decision making.

Not that mining crypto currencies would be nearly the biggest problem should/when the scenario plays out. There's going to be plenty of much more urgent stuff to concentrate on.

- Jyri
--
Altcoin.Center

This reminds me of the plot of a movie...Planet of the Apes 2! It's cool how there's both extremes to the matter; both sides have very valid points...

[pandalion98]

Well this is a silly question that was asked over and over in the past. Start using search.
An EMP to hit out 95% of the miners, would need to be an EMP around the whole world thus wiping out 100% of the Miners and everything else. That would create chaos in which no currency would matter at all.
As far as all other things go, there is no way that someone could force 95% of the Miners to shut down. There are just no possible means of achieving this.

So what would happen doesn't really matter, because it won't happen.
~Lauda

This is almost certainly correct. It would be very unlikely that any event would knock out the vast majority (95%) of the mining network but not the internet (which is required in order for the miners to wish to continue to mine as without the internet they will have no way of broadcasting their blocks and no way of knowing what the latest block that has been mined is).

I would "accept" scenarios in which much smaller portions of the mining network are taken offline, but not 95%

Both me and a significant portion of scientists specialized in events related to Sun and the geomagnetic field would disagree.

It is instead a well known fact that a big CME will eventually blow the lights out of possibly whole continents.

I've been involved in a very high level team mapping the significance of this issue on a national level and I can assure you it's not some fringe theory. It's been taken very seriously on very high levels of governmental decision making.

Not that mining crypto currencies would be nearly the biggest problem should/when the scenario plays out. There's going to be plenty of much more urgent stuff to concentrate on.

- Jyri
--
Altcoin.Center

This reminds me of the plot of a movie...Planet of the Apes 2! It's cool how there's both extremes to the matter; both sides have very valid points...

Indeed.

I'm learning a lot right now.

[pandalion98]

Well this is a silly question that was asked over and over in the past. Start using search.
An EMP to hit out 95% of the miners, would need to be an EMP around the whole world thus wiping out 100% of the Miners and everything else. That would create chaos in which no currency would matter at all.
As far as all other things go, there is no way that someone could force 95% of the Miners to shut down. There are just no possible means of achieving this.

So what would happen doesn't really matter, because it won't happen.
~Lauda

This is almost certainly correct. It would be very unlikely that any event would knock out the vast majority (95%) of the mining network but not the internet (which is required in order for the miners to wish to continue to mine as without the internet they will have no way of broadcasting their blocks and no way of knowing what the latest block that has been mined is).

I would "accept" scenarios in which much smaller portions of the mining network are taken offline, but not 95%

Both me and a significant portion of scientists specialized in events related to Sun and the geomagnetic field would disagree.

It is instead a well known fact that a big CME will eventually blow the lights out of possibly whole continents.

I've been involved in a very high level team mapping the significance of this issue on a national level and I can assure you it's not some fringe theory. It's been taken very seriously on very high levels of governmental decision making.

Not that mining crypto currencies would be nearly the biggest problem should/when the scenario plays out. There's going to be plenty of much more urgent stuff to concentrate on.

- Jyri
--
Altcoin.Center

Aside from HAM radio and the internet, what else do you think will make a suitable transmission medium for the blockchain?

[pandalion98]

Summary so far:

•It would take a long time.
•Difficulty would take a long time to readjust.
•Old miners get reactivated.
•Impossible!
•It is possible.
•There are alternative transmission mediums.
•Planet of the apes.

[TheNinja]

Summary so far:

•It would take a long time.
•Difficulty would take a long time to readjust.
•Old miners get reactivated.
•Impossible!
•It is possible.
•There are alternative transmission mediums.
•Planet of the apes 2!!

Fixt. And dat triple post doe haha. You didn't summarize whether the value would increase/decrease

[Flashman]

Aside from HAM radio and the internet, what else do you think will make a suitable transmission medium for the blockchain?

Pigeons.... http://en.wikipedia.org/wiki/IP_over_Avian_Carriers?


The bandwidth of this tech is getting quite amazing, if one unit moves 4 terabytes in an hour, it's approaching 10 Gigabits per second, does your internet match up?

[altcoin.center]

If this happen you have several possible scenarios.
From price goes sky high to price go to low or even price stay on where it will be in time of this.

Also interesting topic to discuss and sure this can happen someday.

Indeed. The potential problems are plenty and it's very difficult / impossible to predict the exact consequences.

This issue most definitely needs more attention. As of now there seem to be no continuity plans in place whatsoever.

- Jyri
--
Altcoin.Center

[altcoin.center]

He thing there is.
Seriously all rigs are scatter over the world not on one place.
If there were on one place you dont need EMP you can blow up with any explosive.

The fact that the miners are scattered all around is good in some sense and bad in others.

Should anything happen that would disrupt the power grids and/or transcontinental Internet connections, we would immediately have several separated "islands" of block chains that would start living life of their own. The common term for this scenario is "forking".

The problems arise from the fact that when the connections are restored, the chain with the most work put to it is going to win; i.e. the forks that have less work done would in effect become invalid, invalidating all work and all transactions that have happened in that fork after the forking.

If all mining would stop the moment a fork happens, it would be relatively easy to merge the chains later on. However, if we have several forks that all have work (hashing power) put to them, sorting the mess out later on would be very difficult if not impossible.

It baffles me why this issue has been so completely ignored. Many seem to believe nothing will ever happen that would break the international Internet connections in a way that would lead to problems described in this thread. However, both common sense and hard facts clearly show that such ultimate trust to the capability of Internet to persist are completely unfounded. All that is needed is one underwater volcanic eruption at the right spot, one big enough coronal mass ejection from the Sun, or one carefully targeted terrorist attack (false flag or real deal) and the block chains of all crypto currencies would be in chaos.

The fact that Bitcoin has many users does not make it one bit less vulnerable - in fact it's exactly the other way around, since big number of users would mean big amounts of transactions and mining taking place in each fork.

I've been putting significant amounts of time and energy into finding solutions that would minimize the risk of forking shoud, for example, Europe and Americas become disconnected from each other. As a systems architect with a background in security and disaster planning I see this not as a doomy & gloomy scenario but rather as a very interesting and inspiring challenge. There are ways to minimize the risk. I'll get back to those in a moment in another reply to this thread.

- Jyri
--
Altcoin.Center

[altcoin.center]

Aside from HAM radio and the internet, what else do you think will make a suitable transmission medium for the blockchain?

This is a very interesting issue indeed to which I've given considerable amounts of brainpower lately. It happens to be a question I've worked with before when designing emergency communications systems and alike.

HAM would be great as a backup system in many ways, and very limited in others. First of all it's half duplex, i.e. data can move only one direction at a time. All coins in existence today use TCP as their transport layer, and TCP relies heavily in two-way connections. This combined with the fact that a typical speed for a HAM based data connection is anywhere between 300 - 2400 BAUD (anyone remember what BAUD is? means the transfers would be extremely slow. HAM can and most definitely should be part of the backup plan, but other options are needed as well.

Basically any system that allows transferring data (preferably in full duplex) would be usable as a backup. Solutions that would only be usable as long as at least part of the infrastructure work include mobile data, satellite phones, old school modems, or any Internet based service such as e-mail, irc or ssh. As long as the Net is even partially functional, Tor and I2P can help a lot since they can go around the routing limitations and breakages of the "normal" routing topology - at least up to certain extent.

Hack based systems that would only work over short distances could include ideas such as having two laptops with web cameras pointed at each other, and the data being transmitted by encoding it as a series of blinks displayed on the screen; i.e. white screen = 1, black screen = 0 etc. Doable, even easily, but only works over rather short distances.

The more exotic light based solutions include communications using laser bounce from Moon; i.e. the data would be encoded in laser light that would be pointed to the Moon, and the reflection being read by the receiving end. If both ends have all the gear then two-way connections would of course be possible. This, however, is rather sci-fi stuff - doable and it has been done already, but it requires very expensive gear and lots of expertise.

Since a complete catastrophe that would totally blow out the electricity and the Internet is less likely than something that would only cripple them, even the most simple solutions including Tor with perhaps some modem based backups could save a lot. All that is needed are few well networked "bridges" over the communications gaps.

Altcoin.Center's addnode seed network is one attempt to come up with a backup system that can cope with at least certain level of Internet breakdown. Our seed nodes are connected to each other using a handful of backup channels, although they are all depend on at least some level of Internet connectivity to remain. If something happens that brings down the whole net (or the very high quality server systems where our nodes are hosted) then the situation is probably so bad that block chains are the last thing to think about. However, in a scenario where problems would be in the scale of 90% traffic between US and Europe being lost, solutions such as our addnode seed network could save the day.

We're currently at a beta test phase, hosting a handful of chosen altcoins on our servers. More servers and more currencies will be added shortly, and the network will also be providing backup communications systems in the form of P2P backed up IRC network etc. If anyone is interested in participating by, for example, maintaining a seed node in his or her area, please PM me. We're not getting any money out of this and maintaining the servers do have costs so all kinds of support is warmly welcome.

- Jyri
--
Altcoin.Center