First Bitcoin, then Blockstream Satellite. How about we go fully decentralized?

[20kevin20]

I think that one of the problems Bitcoin will be facing over the long term is the aftermath of some disastrous events. I'm talking about events leading to internet blackouts or power cuts. These events include but are not limited to strong cyber attacks, fuel shortage (see Lebanon), earthquakes and so on.

If power or the internet goes down, it's safe to assume that Bitcoin becomes practically worthless/useless in an instant for anyone who's living the aftermaths. We're talking about situations like the current one Lebanon is facing. Had this happened in a much larger nation like the US, I think Bitcoin would've confronted a huge sell-off and loss of interest/trust.

We currently have Blockstream's Satellite which can be either a DIY setup or you could buy the equipment (when it's in stock anyway) off their website AFAIK. I read every now and then a bit about it, but I never had much interest in it. The reason? It's seemingly difficult for a beginner to set it up, it isn't the most portable thing you can have and it's not affordable for the regular guy. Can't see the regular Bitcoiner to own a Satellite setup.

On the other hand, there is GoTenna with their TxTenna. This one is portable, it's much cheaper but as far as I know, the company behind it doesn't care much about the regular GoTennas anymore since they took the military equipment more seriously. When you have a new company providing the regular Joes a way to go off-grid and independent from ISPs or network carriers, you as a military force have to bait them and pull them away from the average Joes .. anyway.

There must be a way to create a device that is affordable, portable and allows you at the same time to be your own bank without depending on ISPs or network carriers no more. I might be very wrong, but I think ham radios can be used to send e-mails. Not sure if there are any ham radios that you can use without a license in some countries (e.g. the US), but perhaps Bitcoin transactions could be transmitted through radio frequencies? There were some kind of radios that you could transmit over a range of up to .. 200 miles (or kms) as well? Is there absolutely no way this can be done?

We have so much technology to use and Bitcoin is imo still just at the beginning. Building a rechargeable device that allows for fully offline Bitcoin txs to happen would make it about invincible even in disastrous events. Is this a bad/impossible-to-realise idea? What do you think?

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[n0nce]

Cool topic! I'm a big proponent of a new, independent network, similar to how the Internet itself was first created way back. Independent and more resilient than the current infrastructure.
Keep in mind: a network just for Bitcoin poses a few issues. For one, everyone will know if you use this network, that you use it for Bitcoin. Furthermore, it can be more easily banned or prohibited. It would be better if this new network was more generic and e.g. we also had messengers operating through it.

If power or the internet goes down, it's safe to assume that Bitcoin becomes practically worthless/useless in an instant for anyone who's living the aftermaths. We're talking about situations like the current one Lebanon is facing. Had this happened in a much larger nation like the US, I think Bitcoin would've confronted a huge sell-off and loss of interest/trust.

Online banking or traditional banks in general are as reliant on electricity and internet as well, though. I am pretty confident even a brick-and-mortar bank doesn't work without internet connectivity. Did people lose all trust in their bank when they couldn't go there due to blackout? I haven't encountered this so far.

I think ham radios can be used to send e-mails.

That's correct; you can even run a complete TCP/IP stack over ham radio. However, it requires a license (at least in all the countries I know of), very specialized hardware and no encryption is allowed. That's the biggest culprit in my opinion. No TLS! No bueno, in my honest opinion.

Encryption, for example, is not generally permitted in the Amateur Radio service

There were some kind of radios that you could transmit over a range of up to .. 200 miles (or kms) as well? Is there absolutely no way this can be done?

Yes, it depends on the frequency and thus on antenna size though. For example very low frequency signals travel insanely far, but have a terrible data rate and require antennas literally the height of someone's home.

We have so much technology to use and Bitcoin is imo still just at the beginning. Building a rechargeable device that allows for fully offline Bitcoin txs to happen would make it about invincible even in disastrous events. Is this a bad/impossible-to-realise idea? What do you think?

It's certainly possible to build and I'm very interested in the topic. One feasible way is to create a 2.4GHz mesh network using directional antennas. It should be possible by repurposing 2.4GHz routers with a custom firmware and attaching directional / parabolic antennas to them, of course positioned outside. The ranges as far as I know are around 10-20km, so you'd need a few people in every city running one such thing to get a good coverage. That's why I say mesh network.

Here's an unrelated video that shows what off-the-shelf hardware can do in the 2.4GHz band:
https://youtu.be/15JmpVAuzZY

[PrimeNumber7]

I think that one of the problems Bitcoin will be facing over the long term is the aftermath of some disastrous events. I'm talking about events leading to internet blackouts or power cuts. These events include but are not limited to strong cyber attacks, fuel shortage (see Lebanon), earthquakes and so on.

If power or the internet goes down, it's safe to assume that Bitcoin becomes practically worthless/useless in an instant for anyone who's living the aftermaths. We're talking about situations like the current one Lebanon is facing. Had this happened in a much larger nation like the US, I think Bitcoin would've confronted a huge sell-off and loss of interest/trust.

Immidiately after any of the examples you provide, the percentage of barter transactions tends to go way up. There tends to be less use for actual money, and more use for tangible goods used to survive, such as food, fuel, and water.

I don't think any kind of "mesh" network is going to work very well when there are many users involved, or when it needs to cover the entire globe (or even large parts of the world). A mesh network greatly increases the chances of a Sybil attack and makes detecting such an attack much more difficult. There are also privacy implications to using radios to use bitcoin, as it would become trivial for anyone in your area to know you are using bitcoin; this is compared to only your ISP knowing you are using bitcoin currently.

[pooya87]

If power or the internet goes down, it's safe to assume that Bitcoin becomes practically worthless/useless in

The word is "unusable" not useless.

an instant for anyone who's living the aftermaths. We're talking about situations like the current one Lebanon is facing. Had this happened in a much larger nation like the US, I think Bitcoin would've confronted a huge sell-off and loss of interest/trust.

There are two problems here, first if you can't move your bitcoins you can't sell them off. Second is that if there is such an aftermath you can't use your fiat either so there is no point in selling bitcoin to get another unusable thing!

We currently have Blockstream's Satellite

In many ways, this is centralized because the satellite is owned by a company (located in US!) and they can decide what services they provide and to whom.

The reason? It's seemingly difficult for a beginner to set it up, it isn't the most portable thing you can have and it's not affordable for the regular guy. Can't see the regular Bitcoiner to own a Satellite setup.

Exactly. In my opinion if we can't use something with the tools we already have in our possession it is not going to be a widely used thing.

ham radios

The problem is range, it is too short. According to google it is between 3 to 28 kilometres (2 to 18 miles).
Besides any "disastrous event" could take out radio towers too making any kind of longer distance communication impossible.

There were some kind of radios that you could transmit over a range of up to .. 200 miles (or kms) as well?

I believe they use the towers (as booster) which is basically a middle man.

[20kevin20]

Keep in mind: a network just for Bitcoin poses a few issues. For one, everyone will know if you use this network, that you use it for Bitcoin. Furthermore, it can be more easily banned or prohibited. It would be better if this new network was more generic and e.g. we also had messengers operating through it.

Of course! The more you could do on the network, the better. If you look at GoTenna's slow loss of ground in this area of development (I'm talking about the development and existence in the open, retail markets and not military who already own a ton of unknown tech anyway), you would further understand that such a device would be likely treated as a threat to the existing banking system. I'm actually in fact surprised that TxTenna hasn't met a backlash from the governments (although I think the fact that GoTenna doesn't maintain their products anymore could be taken as an indirect backlash...)

Online banking or traditional banks in general are as reliant on electricity and internet as well, though. I am pretty confident even a brick-and-mortar bank doesn't work without internet connectivity. Did people lose all trust in their bank when they couldn't go there due to blackout? I haven't encountered this so far.

I actually do think people got much more scared of banks whenever they had problems with them. Think India when their banknotes suddenly got taken out of circulation, or think any disastrous event/crisis where the people couldn't take their own money out of their own accounts. In such events, had Bitcoiners had a device as mentioned in the OP, you can only imagine how much ground BTC would earn in front of banks. Over-the-air transactions in an offline environment. It's like solving one of the biggest flaws of the banking system.

Yes, it depends on the frequency and thus on antenna size though. For example very low frequency signals travel insanely far, but have a terrible data rate and require antennas literally the height of someone's home.

I've been looking for its name, but I still got no clue. There was one particular way of communication through radio that was sending the signals up to the sky and then back to Earth rather than horizontally, which extended its range significantly and eliminated the issue of waves being blocked by certain obstacles.

It's certainly possible to build and I'm very interested in the topic. One feasible way is to create a 2.4GHz mesh network using directional antennas. It should be possible by repurposing 2.4GHz routers with a custom firmware and attaching directional / parabolic antennas to them, of course positioned outside. The ranges as far as I know are around 10-20km, so you'd need a few people in every city running one such thing to get a good coverage. That's why I say mesh network.

Here's an unrelated video that shows what off-the-shelf hardware can do in the 2.4GHz band:
https://youtu.be/15JmpVAuzZY

Interesting. Wouldn't it be possible for such a device specifically for BTC & messaging (perhaps messaging on blockchain) to be produced en masse with a very low cost (<$100, perhaps even <$50)? With Ledger's success, I can only imagine how insane it'd be to have a massive mesh network like that specifically run for Bitcoin. The only issue I see is, if people don't get incentivized for using the mesh network, they will probably not keep them up-and-running 24/7. In the event of blackouts that would likely change, but still.

What about a mesh device with a built-in lincense-requiring radio transmitter/receiver? As far as I know, during disasters ham radio licenses for example are not necessary anymore. Not sure if massive blackouts or power cuts trigger this as well.

Immidiately after any of the examples you provide, the percentage of barter transactions tends to go way up. There tends to be less use for actual money, and more use for tangible goods used to survive, such as food, fuel, and water.

I don't think any kind of "mesh" network is going to work very well when there are many users involved, or when it needs to cover the entire globe (or even large parts of the world). A mesh network greatly increases the chances of a Sybil attack and makes detecting such an attack much more difficult. There are also privacy implications to using radios to use bitcoin, as it would become trivial for anyone in your area to know you are using bitcoin; this is compared to only your ISP knowing you are using bitcoin currently.

I agree with you about the barter part - but I think it's safe to assume that the levels of barter use go significantly up in these kind of events specifically due to the instant distrust in fiat/banking system. If Bitcoin was there to be used even fully offline, this would change.

About the security & privacy of such an idea, I don't know much so thanks for underlining these issues. It's definitely not the most reliable thing, although perhaps there is one key solution we just haven't thought about yet.

There are two problems here, first if you can't move your bitcoins you can't sell them off. Second is that if there is such an aftermath you can't use your fiat either so there is no point in selling bitcoin to get another unusable thing!

I think cash would still work, unless people stop trusting fiat at all due to the likely extremely high sudden price changes (black markets & barter) and due to the loss of purchasing power. And if that happens but Bitcoin can still be used, then I think it's a winning situation for BTC. The point isn't selling it for fiat but rather using it as a currency instead.

The problem is range, it is too short. According to google it is between 3 to 28 kilometres (2 to 18 miles).
Besides any "disastrous event" could take out radio towers too making any kind of longer distance communication impossible.

There were some kind of radios that you could transmit over a range of up to .. 200 miles (or kms) as well?

I believe they use the towers (as booster) which is basically a middle man.

Answered this above, still can't find its name. It transmits radio waves vertically rather than horizontally. Not very sure about using towers as boosters.

[pooya87]

I think cash would still work, unless people stop trusting fiat at all due to the likely extremely high sudden price changes (black markets & barter) and due to the loss of purchasing power.

Of course cash will still work but the problem is that you should have had cash already before the "event" otherwise considering the fact that almost everyone stores their fiat in banks and the banking system can also be affected by the same "event" we can assume people's access to their fiat is cut off.
I think it was Bangladesh a couple of years ago when people formed long queues in front of banks to get their cash out and the banks didn't allow them. Life practically stopped and it showed people don't really store cash.

[BlackHatCoiner]

It's nice seeing that there's always some sort of enthusiasm for a new invention. The intelligent part of this innovative technology is that it incentivizes you to think likewise.

I think that one of the problems Bitcoin will be facing over the long term is the aftermath of some disastrous events. I'm talking about events leading to internet blackouts or power cuts.

I think that's fearmongering.

Everything is built to operate online; the whole world moves (and has already moved) their businesses to the internet. There are stores which only exist in the internet. Part of the education system is done from distance. The communication etc. Saying that one of the problems Bitcoin will face is this kind of disastrous event is trembling the least.

Lots of other events will occur in such scenario which will affect the economy much worse.


BTW, lightning doesn't always require internet connection.

[o_e_l_e_o]

Answered this above, still can't find its name. It transmits radio waves vertically rather than horizontally.

The term you are looking for is skywave propagation, as opposed to ground wave propagation.

I would agree with the feeling that mesh networks are not really a workable long-term solution. In the event of a city or country wide black out or similar, then your mesh network still requires someone to be connected to the internet to relay information back and forth to the rest of the network. It's one thing to trust that person to broadcast a transaction for you, but it's another altogether for an entire town or city to be relying on one person's internet connected node to relay all the information through the mesh network. I suppose you could partly mitigate this by also running your own node via Blockstream Satellite.

[aliashraf]

In the event of a city or country wide black out or similar, then your mesh network still requires someone to be connected to the internet to relay information back and forth to the rest of the network. It's one thing to trust that person to broadcast a transaction for you, but it's another altogether for an entire town or city to be relying on one person's internet connected node to relay all the information through the mesh network. I suppose you could partly mitigate this by also running your own node via Blockstream Satellite.

It is not required to have just "one person" in charge of connecting the mesh to the rest of the world, multiple paths could exist supported by a smart gateway protocol. I'd suggest such a mesh based approach using mobile devices as a default topology even for day-to-day low bandwidth use cases and not just extreme conditions.

[DaveF]

As others have said, if things get that bad that we have no power and no internet then not being able to get to your BTC is the least of your problems.
The run on banks for cash, is one thing, but if you want to buy something unless the merchant also has some way of converting the BTC that you could get them through whatever method to something they want (cash / gold / whatever) then they will probably not take it.

As for satellite, with starlink coming online and kuiper a few years off and there was another one whos name I don't remember although they will be controlled by big corporate entities there should be enough different ones out there to keep prices low and bandwidth up.

Ham radios and such will never be able to keep up and if you think that blockstream satellite is expensive, look at the price of a good ham rig and antenna.

-Dave

[NeuroticFish]

Building a rechargeable device that allows for fully offline Bitcoin txs to happen would make it about invincible even in disastrous events. Is this a bad/impossible-to-realise idea? What do you think?

Sorry, I think that the solution is missing something important and it becomes kind of worthless as it is.
Imho complete blackout of the entire internet and electricity is not really possible for reasons like shortages. Or, let's say, the chances for that are way too small to matter.
Imho the only actual problem is massive solar flares/coronal mass ejections/geomagnetic storms which can indeed shut down... maybe everything. But in such a case even the satellites aren't safe.

I don't know what would be the correct solution, but we seem to try to address problem with lower chance to occur and it may be better to focus on the bigger problem; if that's handled, the smaller one will also be solved.

[o_e_l_e_o]

It is not required to have just "one person" in charge of connecting the mesh to the rest of the world, multiple paths could exist supported by a smart gateway protocol. I'd suggest such a mesh based approach using mobile devices as a default topology for low bandwidth use cases.

Sure, but what is the likelihood of such a scenario? In such a case where there is a city wide black out, but enough internet coverage via cellular or satellite for multiple connections throughout the city in question, then how necessary is a mesh network? If some people can still get online via cellular or satellite, then surely most people can still get online? And the few who can't are much more likely to simply use someone else's connection or some public hotspot than they are to set up a mesh network. If there was a mesh network already functioning, then sure, but there is pretty much zero incentive for people to set one up or maintain it for some very hypothetical situation in which not trading bitcoin would be the least of your concerns.

[ABCbits]

There's no thing such as full/absolute decentralization.

I'm actually in fact surprised that TxTenna hasn't met a backlash from the governments (although I think the fact that GoTenna doesn't maintain their products anymore could be taken as an indirect backlash...)

Maybe because it's not popular? For comparison, their github repository (https://github.com/MuleTools/txTenna) only have 71 stars, while blockstream satellite (https://github.com/Blockstream/satellite) have 822 stars.

[aliashraf]

If some people can still get online via cellular or satellite, then surely most people can still get online? 

Not necessarily true, actually one could list dozens of scenarios in which your argument doesn't hold.

There is pretty much zero incentive for people to set one up or maintain it for some very hypothetical situation in which not trading bitcoin would be the least of your concerns.

It is not just about trading Bitcoin, in the bigger picture, it is about preserving tcp/ip connectivity exploiting its essential inherent decentralized nature and resistance against single points of failure. As of your lack of incentive argument, I suppose it is an open issue that needs further innovations and more elegant ideas.

[n0nce]

ham radios

The problem is range, it is too short. According to google it is between 3 to 28 kilometres (2 to 18 miles).
Besides any "disastrous event" could take out radio towers too making any kind of longer distance communication impossible.

There were some kind of radios that you could transmit over a range of up to .. 200 miles (or kms) as well?

I believe they use the towers (as booster) which is basically a middle man.

It is possible to transmit thousands of kilometers without boosters of any kind; I don't know that something like this is even used much in ham radio. Usually, HF signals can be bounced at the ionosphere and travel around the whole globe without any need of something like that.

It's certainly possible to build and I'm very interested in the topic. One feasible way is to create a 2.4GHz mesh network using directional antennas. It should be possible by repurposing 2.4GHz routers with a custom firmware and attaching directional / parabolic antennas to them, of course positioned outside. The ranges as far as I know are around 10-20km, so you'd need a few people in every city running one such thing to get a good coverage. That's why I say mesh network.

Here's an unrelated video that shows what off-the-shelf hardware can do in the 2.4GHz band:
https://youtu.be/15JmpVAuzZY

Interesting. Wouldn't it be possible for such a device specifically for BTC & messaging (perhaps messaging on blockchain) to be produced en masse with a very low cost (<$100, perhaps even <$50)? With Ledger's success, I can only imagine how insane it'd be to have a massive mesh network like that specifically run for Bitcoin. The only issue I see is, if people don't get incentivized for using the mesh network, they will probably not keep them up-and-running 24/7. In the event of blackouts that would likely change, but still.

Yes, everyone can just buy one such antenna for around $50 and an existing router with custom firmare & build a mesh network. They need UPS though for it to make any sense in a blackout so it will be a bit more than $100 and a good firmware + lots and lots of participants. Keep in mind there are only around ~10.000 BTC nodes worldwide. You'd need more than that in each country to have a working mesh net.

What about a mesh device with a built-in lincense-requiring radio transmitter/receiver? As far as I know, during disasters ham radio licenses for example are not necessary anymore. Not sure if massive blackouts or power cuts trigger this as well.

Ham radio laws are very tight. I don't think a blackout immediately allows you to use ham radio. Furthermore, in the stress of a real disaster, nobody wants to first sit down and setup their ham mesh Bitcoin node stuff. It has to be up and running before, be all configured and connected beforehand, realistically. And that's 100% not allowed without ham license on ham radio frequencies. (like HF bands which cover larger distances)

I think cash would still work, unless people stop trusting fiat at all due to the likely extremely high sudden price changes (black markets & barter) and due to the loss of purchasing power. And if that happens but Bitcoin can still be used, then I think it's a winning situation for BTC. The point isn't selling it for fiat but rather using it as a currency instead.

I agree, it would be sick to have another independent and more resilient network in general; not just for Bitcoin. But if it's pushed and mainly used for Bitcoin, it would surely help BTC reputation

Everything is built to operate online; the whole world moves (and has already moved) their businesses to the internet. There are stores which only exist in the internet. Part of the education system is done from distance. The communication etc. Saying that one of the problems Bitcoin will face is this kind of disastrous event is trembling the least.

Lots of other events will occur in such scenario which will affect the economy much worse.

I very much agree with this; however, IF Bitcoin could show that it works even when literally everything else doesn't, would be a quite sick feat! However, I don't think it's a downside for Bitcoin that it's (right now) fully reliant on internet; since everything else is as well. So it's kind of a level playing field.

I'd suggest such a mesh based approach using mobile devices as a default topology even for day-to-day low bandwidth use cases and not just extreme conditions.

There are multiple research studies on this topic already; especially a few years back, when Android was more open :sigh: and it was possible to do cool things with its 2.4GHz antenna easily. Not sure what's the state of the art right now, but I haven't heard much about it since. The biggest issue is that it requires even more participants than if using home routers and directional antennas (which is the best idea for me so far).

As for satellite, with starlink coming online and kuiper a few years off and there was another one whos name I don't remember although they will be controlled by big corporate entities there should be enough different ones out there to keep prices low and bandwidth up.

Unfortunately, satellite internet is a quite bad idea in general, for a variety of reasons. A few weeks ago, I stumbled upon this video, which points out lots of serious issues with Starlink and the whole idea in general. In short, it makes very little sense for the majority of people, in fact the technology can't even feasibly serve as many people as Musk claims and thus it never will. It is and will stay a niche market due to price and technological reasons (max. base stations per satellite, satellites need to be replaced from time to time => more cost etc).
DEBUNKING STARLINK

[PrimeNumber7]

Immidiately after any of the examples you provide, the percentage of barter transactions tends to go way up. There tends to be less use for actual money, and more use for tangible goods used to survive, such as food, fuel, and water.

I don't think any kind of "mesh" network is going to work very well when there are many users involved, or when it needs to cover the entire globe (or even large parts of the world). A mesh network greatly increases the chances of a Sybil attack and makes detecting such an attack much more difficult. There are also privacy implications to using radios to use bitcoin, as it would become trivial for anyone in your area to know you are using bitcoin; this is compared to only your ISP knowing you are using bitcoin currently.

I agree with you about the barter part - but I think it's safe to assume that the levels of barter use go significantly up in these kind of events specifically due to the instant distrust in fiat/banking system. If Bitcoin was there to be used even fully offline, this would change.

Why do you think people start to distrust the banking system after a natural disaster? I would argue that barter transactions increase because people have less use for anything that can be described as a store of value -- people need actual goods/services that allow them to survive.

About the security & privacy of such an idea, I don't know much so thanks for underlining these issues. It's definitely not the most reliable thing, although perhaps there is one key solution we just haven't thought about yet.

If you are in a rural or even a suburban area, with a mesh network, it would take a very small number of dishonest nodes to pull off a Sybil attack that affects a large portion of the entire network, as all traffic is flowing through so few nodes. There is little reason to run a node in a sparsely populated area because it will connect to so few people.

We currently have Blockstream's Satellite

In many ways, this is centralized because the satellite is owned by a company (located in US!) and they can decide what services they provide and to whom.

My understanding is that the blockstream satellite will broadcast transactions to anyone whose "antenna" is pointed in the appropriate direction, and has no way of discriminating against a specific user.

Using a blockstream satellite alone will not allow someone to broadcast a transaction, which would be important in a power/internet outage. 

[dkbit98]

We should not be surprised to see some temporary and fabricated electricity shutdown like some insane individuals announced it months ago, with purpose of crashing global economy,
but I don't expect this to happen globally in all countries in the same time, so Bitcoin transactions should not stop, especially in US that have many states with separate independent systems.
There is one cool project from Brazil for creating bitcoin stations for listening and broadcasting of transactions, but you would still need electricity for operating radio, so maybe physical Bitcoins will be used much more than now, and not only as collectible items.
https://satoshi.radio.br/wp/

[NeuroticFish]

https://satoshi.radio.br/wp/

I find it interesting that they plan to make it available also as a DYI station. It would be nice for those having their own solar panels, for example.
Of course, the approval can be a problem...

Important to remember that it is still in development, not in use, and should be approved first by authorities, before release the protocol.

[20kevin20]

Wow, there are so many more answers than I expected. Thanks to you all for the replies.

So I think the scenario in which a nation-wide blackout occurs is not that far from reality. It is already being speculated that a quite dark winter is on the way, and I agree with dbkit98: there are some sick individuals who are looking for a global reset, and it's not the reset itself that is to be worried about but the way it's going to happen. "You will own nothing, and you will be happy". They said it themselves, and we're looking at a number of leaders who don't like Bitcoin even now, even today.

A massive blackout or a regulated Internet v2.0 might mean Bitcoin's disappearance or turning it into a massive surveillance tool. While thinking about this mesh as a "survival/emergency" tool (and I think there would actually in fact be a quite big market for it, considering how large the "preppers" community is), I also saw it as a way of ensuring that even if someone wants to take Bitcoin down indirectly through disastrous scenarios, it would still thrive at least partially within our community.

Of course, there will be some of you here who will contradict me or think that this is just being paranoid or so, but I personally think that the current financial system isn't the happiest with Bitcoin's presence and there is nothing that can make it stronger than proving it is not just something virtual/temporary but something that you can rely on even in such events.

So far, I think the Satoshi Radio from Brazil is the closest I can get to what I was thinking about. Will definitely research more about how it works, although I think that unless this capability of receiving/broadcasting txs is embedded into a device specifically created for offline over-the-air Bitcoin transactions, it would be useless in the events previously mentioned (how many people would use the OTA Bitcoin receiver/transmitter .. let alone the Satoshi Radio?).

But besides radio waves, is there no other technology using waves or something that could be used over very long distances without a necessary license/SIM card?

[kano]

As mentioned a number of times already, if you need cash to survive, and there's no electricity, well, you can't convert your BTC to cash.

If there's not enough electricity to run anything normal, you wont have enough to run a world wide bitcoin network for everyone to use.
You will not find the world suddenly turn to BTC, they'll turn to something physical, like cash or gold (yep good idea to keep some gold ...)

Nationwide blackout, well, maybe in the 3rd world, or under authoritarian rule, but in the west, and a lot of europe, not gonna happen.
It's like worry about the world being destroyed by an asteroid ... why didn't you mentioned that as well

Fun to be one of those people with 24/7 solar power/battery at the end of the world